U.S. patent application number 10/790039 was filed with the patent office on 2004-09-02 for semiconductor plastic package and process for the production thereof.
Invention is credited to Gaku, Morio, Ikeguchi, Nobuyuki, Yamane, Nobuyuki.
Application Number | 20040171189 10/790039 |
Document ID | / |
Family ID | 27585890 |
Filed Date | 2004-09-02 |
United States Patent
Application |
20040171189 |
Kind Code |
A1 |
Gaku, Morio ; et
al. |
September 2, 2004 |
Semiconductor plastic package and process for the production
thereof
Abstract
A semiconductor plastic package excellent in heat diffusibility
and free of moisture absorption, is structured by fixing a
semiconductor chip on one surface of a printed circuit board,
connecting a semiconductor circuit conductor to a signal
propagation circuit conductor formed on a printed circuit board
surface in the vicinity thereof by wire bonding, at least
connecting the signal propagation circuit conductor on the printed
circuit board surface to a signal propagation circuit conductor
formed on the other surface of the printed circuit board or a
connecting conductor pad of a solder ball with a through-hole
conductor, and encapsulating the semiconductor chip with a resin.
The printed circuit board has a metal sheet of nearly the same size
as the printed circuit board and is nearly in the center in the
thickness direction of the printed circuit board. The metal sheet
is insulated from front and reverse circuit conductors with a
heat-resistant resin composition, and the metal sheet is provided
with a clearance hole having a diameter greater than a diameter of
each of at least two through holes. The through-holes are provided
in the clearance hole, and a through-hole or through-holes are
insulated from the metal sheet with a resin composition, with at
least one through-hole being connected to the metal sheet. One
surface of the metal sheet is provided with at least one protrusion
portion which is of the same size as the semiconductor chip and
exposed on a surface, and the semiconductor chip is fixed on the
protrusion portion.
Inventors: |
Gaku, Morio; (Tokyo, JP)
; Ikeguchi, Nobuyuki; (Tokyo, JP) ; Yamane,
Nobuyuki; (Tokyo, JP) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK, L.L.P.
2033 K STREET N. W.
SUITE 800
WASHINGTON
DC
20006-1021
US
|
Family ID: |
27585890 |
Appl. No.: |
10/790039 |
Filed: |
March 2, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10790039 |
Mar 2, 2004 |
|
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|
10036385 |
Jan 7, 2002 |
|
|
|
6720651 |
|
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|
|
10036385 |
Jan 7, 2002 |
|
|
|
09207115 |
Dec 8, 1998 |
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6376908 |
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Current U.S.
Class: |
438/106 ;
257/E23.004; 257/E23.105 |
Current CPC
Class: |
H01L 2924/0103 20130101;
H01L 2924/12042 20130101; H01L 2924/01006 20130101; H05K 2203/049
20130101; H01L 2924/1532 20130101; H01L 2924/15311 20130101; H01L
2924/00014 20130101; H05K 1/056 20130101; H01L 2924/1433 20130101;
H05K 2201/09054 20130101; H01L 24/48 20130101; H01L 2924/15153
20130101; H01L 2924/1517 20130101; H01L 2924/01019 20130101; H01L
2924/01079 20130101; H05K 1/0204 20130101; H01L 23/13 20130101;
H01L 2924/01078 20130101; H01L 2924/01029 20130101; H01L 2924/181
20130101; H05K 3/06 20130101; H01L 2224/32188 20130101; H01L
23/3677 20130101; H01L 2224/48091 20130101; H01L 2224/48227
20130101; H01L 2924/01082 20130101; H01L 2924/01005 20130101; H05K
3/445 20130101; H05K 3/44 20130101; H05K 2201/0382 20130101; H01L
2224/73265 20130101; H01L 2924/014 20130101; H01L 2224/48091
20130101; H01L 2924/00014 20130101; H01L 2924/12042 20130101; H01L
2924/00 20130101; H01L 2924/181 20130101; H01L 2924/00012 20130101;
H01L 2924/00014 20130101; H01L 2224/45099 20130101; H01L 2924/00014
20130101; H01L 2224/05599 20130101; H01L 2924/00014 20130101; H01L
2224/85399 20130101; H01L 2924/00014 20130101; H01L 2224/45015
20130101; H01L 2924/207 20130101 |
Class at
Publication: |
438/106 |
International
Class: |
B65D 085/24 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 10, 1997 |
JP |
340129/97 |
Jan 13, 1998 |
JP |
4836/98 |
Jan 23, 1998 |
JP |
11528/98 |
Jan 30, 1998 |
JP |
34234/98 |
Jan 30, 1998 |
JP |
34235/98 |
Jan 30, 1998 |
JP |
34236/98 |
Jan 28, 1998 |
JP |
15893/98 |
Jan 29, 1998 |
JP |
17045/98 |
Jan 30, 1998 |
JP |
34238/98 |
Feb 20, 1998 |
JP |
38917/98 |
Jan 12, 1998 |
JP |
3984/98 |
Jan 6, 1998 |
JP |
975/98 |
Jan 13, 1998 |
JP |
4835/98 |
Jan 21, 1998 |
JP |
9567/98 |
Jan 21, 1998 |
JP |
9568/98 |
Jan 30, 1998 |
JP |
34232/98 |
Jan 30, 1998 |
JP |
34233/98 |
Claims
What is claimed is:
1. A process for the production of a double-side metal-foil-clad
laminate for a semiconductor plastic package structured by
disposing a metal sheet of nearly the same size as a printed
circuit board nearly in the center in the thickness direction of
the printed circuit board, providing at least one exposed metal
sheet protrusion of nearly the same size as a semiconductor chip on
one surface of the printed circuit board, fixing the semiconductor
chip thereon, connecting the semiconductor chip to a signal
propagation circuit conductor formed on a printed circuit board
surface in the vicinity thereof by wire bonding, at least
connecting the signal propagation circuit conductor on the printed
circuit board surface to a signal propagation circuit conductor
formed on the other surface of the printed circuit board or a
connecting conductor pad of a solder ball with a through-hole
conductor, and encapsulating the semiconductor chip with a resin,
the process comprising the steps of (1) forming a protrusion on one
surface of the metal sheet for mounting the semiconductor chip, and
forming a clearance hole having a diameter greater than the
diameter of a through-hole or a slit whose minor side is greater
than the diameter of the through-hole for providing the
through-hole for the conduction of front and reverse circuit
conductors, (2) disposing a low-flow or no-flow prepreg sheet or
resin layer having a hole slightly greater than the area of the
protrusion portion on the protrusion position on the side where the
metal protrusion portion is formed, disposing a high-flow prepreg
sheet or resin layer having a resin amount and a resin flow for
being sufficiently filled in the clearance hole on the other side,
and disposing metal foils or single-side metal-foil-clad laminates
on both outer sides thereof, and (3) laminate-forming the resultant
set under heat and under pressure, to integrate it and form a
metal-sheet-inserted dual-side metal-foil-clad laminate.
2. A process according to claim 1, wherein the laminate-formation
is carried out under vacuum.
3. A process according to claim 1, wherein the through-hole
includes a through-hole insulated from the metal sheet with a
heat-resistant resin composition and a through-hole directly
connected to the metal sheet.
4. A process according to claim 1, wherein a heat-diffusing via
hole is made in the reverse surface so as to connect to the metal
sheet and is plated with a metal.
5. A process according to claim 1, wherein the protrusion is formed
on one surface of the metal sheet, and the clearance hole is made,
by the following steps of, (1) forming an etching resist on the
metal sheet surface, (2) forming the protrusion for the
semiconductor chip on one surface by etching, (3) applying a liquid
etching resist to the entire surface of the metal sheet, drying a
coating of the etching resist to remove a solvent, covering a
negative film having a hole made by punching for the metal
extrusion portion on the metal sheet surface, and carrying out
irradiation with ultraviolet light, and (4) dissolving and removing
unexposed resist in the clearance hole portion with a 1% sodium
carbonate aqueous solution, forming the clearance hole by etching
on both sides and removing the etching resist.
6. A process according to claim 1, wherein the step (2) is the step
of (2') disposing a low-flow or no-flow prepreg sheet, a resin
sheet or a coated resin layer having a hole slightly greater than
the area of the protrusion portion on the protrusion position on
the side where the metal protrusion portion is formed, further
disposing a dual-side sheet or multi-layer sheet which has a hole
slightly greater than the area of the metal protrusion portion, has
a circuit on one surface and is chemically surface-treated as
required thereon, disposing a high-flow prepreg sheet, a copper
foil with a resin, a resin sheet or an application-formed resin
layer having a resin amount and a resin flow for being sufficiently
filled in the clearance hole on the other side, and, when the
outside thereof is a resin layer, disposing a metal foil or a
single-side metal-foil-clad laminate.
7. A process according to claim 1, wherein the step (1) is the
steps of (1') disposing an etching resist for forming the
protrusion on part of one surface of the metal sheet, disposing an
etching resist for forming the clearance hole or the slit on the
other surface, and at the etching step, blowing an etching solution
having a lower pressure on the surface where the protrusion is to
be formed and blowing an etching solution having a higher pressure
on the other surface, to form the protrusion portion and the
clearance hole or the slit together.
8. A process according to claim 1, wherein the step (1) is the step
of (1') the protrusion for mounting a semiconductor chip is formed
on one surface of the metal sheet by embossing the metal sheet, to
form a structure in which one surface is protruded and the other
surface is dented.
9. A process according to claim 1, wherein the metal sheet and the
metal for the circuit on the front surface are an alloy having a
copper content of at least 95% or pure copper.
10. A process according to claim 1, wherein the resin composition
for forming the prepreg sheet or the resin layer is a thermosetting
resin composition containing a polyfunctional cyanate ester or a
prepolymer of said cyanate ester.
11. A process according to claim 1, wherein the step (1) includes
the step of forming the protrusion portion which is nearly of the
same size as the semiconductor chip on one surface of the metal
sheet and forming a protrusion portion on a portion corresponding
to part or the whole of a marginal portion of the printed circuit
board, the above step is the step of (1') covering the entire
surface of the metal sheet with a liquid etching resist, then
curing the resist on the protrusion portion on which the
semiconductor chip is to be mounted and the protrusion portion for
heat diffusion on the marginal portion by exposure, removing an
unexposed portion by dissolving, dissolving a predetermined
thickness of the metal sheet by etching, and then removing the
etching resist by dissolving.
Description
[0001] This application is a divisional application of Ser. No.
10/036,385, filed Jan. 7, 2002, which is a divisional application
of Ser. No. 09/207,115, filed Dec. 8, 1998, now Pat. No. 6,376,908,
issued Apr. 23, 2002.
FIELD OF THE INVENTION
[0002] The present invention relates to a novel semiconductor
plastic package in the form of a semiconductor chip mounted on a
small printed circuit board, and a process for the production of a
double-side copper-clad laminate for use in the package. The
semiconductor plastic package is feasible particularly as a
high-watt and multi-terminal high-density semiconductor plastic
package such as a microprocessor, a microcontroller, ASIC or
graphic controller or processor. The present semiconductor plastic
package is mounted on a motherboard printed circuit board with a
solder ball for use as an electronic part or device.
BACKGROUND OF THE INVENTION
[0003] There are conventionally known semiconductor plastic
packages such as a plastic ball grid array P-BGA) and a plastic
land grid array (P-LGA), which are structured by fixing a
semiconductor chip on the upper surface of a plastic printed
circuit board, bonding the semiconductor chip to a conductor
circuit formed on the upper surface of the printed circuit board by
wire-bonding, forming a conductor pad for connection to a
motherboard printed circuit board on the lower surface of the
printed circuit board with a solder ball, connecting front and
reverse circuit conductors through a plated through-hole and
encapsulating the semiconductor chip with a resin. In the above
known structure, a plated heat-diffusible through-hole for
connection from a metal foil on the upper surface for fixing the
semiconductor chip to the lower surface is formed for diffusing
heat generated in the semiconductor chip to the motherboard printed
circuit board.
[0004] There is a risk that moisture may be absorbed into a
silver-powder-containing resin adhesive used for fixing a
semiconductor through the above through-hole and may cause
interlayer swelling due to heating at a time of mounting on the
motherboard or heating when a semiconductor part is removed from
the motherboard. This swelling is called the "popcorn phenomenon."
When the popcorn phenomenon takes place, the package is no longer
usable in most cases, and it is immensely important to overcome the
above phenomenon.
[0005] Further, attaining higher functions of a semiconductor and
increasing a density thereof imply an increase in the amount of
heat to be generated, and the formation of only a through-hole
immediately below the semiconductor chip for diffusing heat is no
longer sufficient.
SUMMARY OF THE INVENTION
[0006] It is an object of the present invention to provide a
semiconductor plastic package having excellent heat diffusibility
for overcoming the problems of an increase in the amount of heat
caused by attaining higher functions of a semiconductor and
increasing a density thereof, and a process for the production
thereof.
[0007] It is another object of the present invention to provide a
semiconductor plastic package which is free of absorption in the
lower surface of a semiconductor chip so that it is remarkably
improved in heat durability after moisture absorption, i.e., the
popcorn phenomenon, and which can be remarkably improved in heat
diffusibility, and a process for the production thereof.
[0008] It is further another object of the present invention to
provide a semiconductor plastic package which is feasible for
mass-production and improved in economic performances and which has
a novel structure, and a process for the production thereof.
[0009] It is still further another object of the present invention
to provide a semiconductor plastic package which is excellent in
heat durability, electric insulation properties after being treated
in a pressure cooker and anti-migration properties owing to the use
of a thermosetting resin composition containing a polyfunctional
cyanate ester or a polyfunctional cyanate ester prepolymer as an
essential component, and a process for the production thereof.
[0010] According to the present invention, there is provided a
semiconductor plastic package structured by fixing a semiconductor
chip on one surface of a printed circuit board, connecting a
semiconductor circuit conductor to a signal propagation circuit
conductor formed on a printed circuit board surface in the vicinity
thereof by wire bonding, at least connecting the signal propagation
circuit conductor on the printed circuit board surface to a signal
propagation circuit conductor formed on the other surface of the
printed circuit board or a connecting conductor pad of a solder
ball with a through-hole conductor, and encapsulating the
semiconductor chip with a resin,
[0011] the printed circuit board having a metal sheet of nearly the
same size as the printed circuit board, and nearly in the center in
the thickness direction of the printed circuit board the metal
sheet being insulated from front and reverse circuit conductors
with a heat-resistant resin composition. The metal plate is
provided with a clearance hole having a diameter greater than the
diameter of each of at least two through-holes, the through-holes
being provided in the clearance hole, and the through-hole or
through-holes being insulated from the metal sheet with a resin
composition. At least one through-hole is connected to the metal
sheet, one surface of the metal sheet being provided with at least
one protrusion portion which is of the same size as the
semiconductor chip and exposed on a surface, the semiconductor chip
being fixed on the protrusion portion.
[0012] According to the present invention, there is also provided a
semiconductor plastic package structured by fixing a semiconductor
chip on one surface of a printed circuit board, connecting a
semiconductor circuit conductor to a signal propagation circuit
conductor formed on a printed circuit board surface in the vicinity
thereof by wire bonding, at least connecting the signal propagation
circuit conductor on the printed circuit board surface to a signal
propagation circuit conductor formed on the other surface of the
printed circuit board or a connecting conductor pad of a solder
ball with a through-hole conductor, and encapsulating the
semiconductor chip with a resin,
[0013] the printed circuit board having a metal sheet of nearly the
same size as the printed circuit board, and nearly in the center in
the thickness direction of the printed circuit board, the metal
sheet being insulated from front and reverse circuit conductors
with a heat-resistant resin composition. The metal plate is
provided with a clearance hole having a diameter greater than the
diameter of each of at least two through-holes, the through-holes
being provided in the clearance hole, and the through-hole or
through-holes being insulated from the metal sheet with a resin
composition. At least one through-hole is connected to the metal
sheet, one surface of the metal sheet being provided with at least
one protrusion portion which is of the same size as the
semiconductor chip and exposed on a surface, the semiconductor chip
being fixed on the protrusion portion, the other surface of the
metal sheet being provided with a protrusion surface exposed for
diffusing heat.
[0014] According to the present invention, further, there is
provided a process for the production of a dual-side
metal-foil-clad laminate for a semiconductor plastic package
structured by disposing a metal sheet of nearly the same size as a
printed circuit board nearly in the center in the thickness
direction of the printed circuit board, providing at least one
exposed metal sheet protrusion of nearly the same size as a
semiconductor chip on one surface of the printed circuit board,
fixing the semiconductor chip thereon, connecting the semiconductor
chip to a signal propagation circuit conductor formed on a printed
circuit board surface in the vicinity thereof by wire bonding, at
least connecting the signal propagation circuit conductor on the
printed circuit board surface to a signal propagation circuit
conductor formed on the other surface of the printed circuit board
or a connecting conductor pad of a solder ball with a through-hole
conductor, and encapsulating the semiconductor chip with a
resin,
[0015] the process comprising the steps of:
[0016] (1) forming a protrusion on one surface of the metal sheet
for mounting the semiconductor chip, and forming a clearance hole
having a diameter greater than the diameter of a through-hole or a
slit whose minor side is greater than the diameter of the
through-hole for providing the through-hole for the conduction of
front and reverse circuit conductors,
[0017] (2) disposing a low-flow or no-flow prepreg sheet or resin
layer having a hole slightly greater than the area of the
protrusion portion on the protrusion position on the side where the
metal protrusion portion is formed, disposing a high-flow prepreg
sheet or resin layer having a resin amount and a resin flow for
being sufficiently filled in the clearance hole on the other side,
and disposing metal foils or single-side metal-foil-clad laminates
on both outer sides thereof, and
[0018] (3) laminate-forming the resultant set under heat and under
pressure, to integrate it and form a metal-sheet-inserted
double-side metal-foil-clad laminate.
BRIEF DESCRIPTION OF DRAWINGS
[0019] FIG. 1 schematically shows steps of producing a plastic
package of the present invention.
[0020] FIG. 2 is a semiconductor-chip-mounted enlarged
cross-sectional view showing a case where the protrusion portion
formed on one surface of a metal sheet has a smaller area than a
semiconductor chip in the present invention.
[0021] FIG. 3 schematically shows a metal sheet in which
slit-shaped clearance holes are formed and a printed circuit board
having the metal sheet.
[0022] FIG. 4 schematically shows steps of further forming a blind
via hole in a dual-side metal-foil-clad laminate produced up to the
step shown in FIG. 1(6), in the steps of producing a semiconductor
plastic package.
[0023] FIG. 5 schematically shows one protrusion portion formed on
a metal sheet by embossing.
[0024] FIG. 6 schematically shows two protrusion portions formed on
a metal sheet-by embossing.
[0025] FIG. 7 schematically shows a semiconductor plastic package
in which a protrusion portion for mounting a semiconductor chip is
formed on one surface of a metal sheet and a protrusion portion for
diffusing heat is formed on the other surface.
[0026] FIG. 8 schematically shows a semiconductor plastic package
in which a protrusion portion for mounting a semiconductor chip is
formed on one surface of a metal sheet and protrusion portions are
formed on the front and reverse surfaces of the metal sheet in
positions corresponding to a circumferential portion of a printed
circuit board.
[0027] FIG. 9 schematically shows a semiconductor plastic package
in which a protrusion portion for mounting a semiconductor chip is
formed on one surface of a metal sheet and protrusion portions are
formed on the reverse surface of the metal sheet in positions
corresponding to a circumferential portion of a printed circuit
board.
[0028] FIG. 10 schematically shows a semiconductor plastic package
in which a protrusion portion for mounting a semiconductor chip is
formed on one surface of a metal sheet and via holes for diffusing
heat are formed so as to reach the metal sheet from a reverse
surface.
[0029] FIG. 11 schematically shows steps of producing a
semiconductor plastic package in Comparative Example 1.
[0030] FIG. 12 schematically shows steps of producing a
semiconductor plastic package in Comparative Example 2.
DETAILED DESCRIPTION OF THE INVENTION
[0031] In the semiconductor plastic package of the present
invention, a metal sheet having excellent heat diffusibility is
disposed in the center in the thickness direction of a printed
circuit board. A plated through-hole for the conduction of front
and reverse circuit conductors has a diameter smaller than a
diameter of a clearance hole made in the metal sheet, and the
plated through-hole is formed nearly in the center of resin that
has filled in the clearance hole so that the insulation of the
through-hole from the metal sheet is secured.
[0032] In a known method of fixing a semiconductor chip on the
upper surface of a printed circuit board having a through-holed
metal sheet as an inner layer, heat from the semiconductor chip is
inevitably transmitted into a heat-diffusing through-hole
immediately below it, like a conventional P-PGA package, and it is
not possible to overcome the popcorn phenomenon.
[0033] The printed circuit board for a semiconductor plastic
package, prepared by the use of a dual-side copper-clad laminate
obtained according to the present invention, is structured as
follows. At least one metal protrosion portion for fixing a
semiconductor chip with a heat-conductive adhesive is exposed on a
board surface. A clearance hole having a diameter greater than a
through-hole diameter is made in a position where a through-hole is
to be formed. A through-hole having a diameter smaller than the
clearance hole diameter is made nearly in the center of the
clearance hole, front and reverse circuits are connected with a
plating, and at least one through-hole is directly connected to the
metal sheet as an inner layer. Therefore, heat generated from a
semiconductor of a plastic package prepared by fixing a
semiconductor chip, wire-bonding it and encapsulating it with a
resin is thermally conducted from a metal portion where the
semiconductor chip is directly mounted to the metal sheet as a
whole. In the above structure, therefore, the heat is transmitted
from a position different from the position immediately below the
semiconductor chip, and it is transmitted to a metal pad on the
lower surface through the through-hole connected to the metal sheet
and is diffused into a motherboard printed circuit board.
[0034] In the present invention, first, at least one protrusion
having a proper size for fixing a semiconductor chip is formed on a
metal sheet by a known etching method, cold machining method or
press-rolling deformation method. The projection portion generally
has a size nearly equal to the size of a semiconductor chip. Then,
a clearance hole is made in a position where a through-hole is to
be formed, by a known etching method, punching method, drilling
method or laser method (FIG. 3). The clearance hole permits the
formation of a through-hole for the front-reverse surface
conduction, and has a size greater than the diameter of the
through-hole to some extent.
[0035] Heat generated by a semiconductor is thermally conducted
from a metal portion on which a semiconductor chip is directly
mounted to the metal sheet as whole, and therefore, at least one
plated through-hole is formed from a place different from the
position immediately below the semiconductor chip to a metal pad on
a lower surface through the metal sheet, so that the heat from the
semiconductor chip is diffused into a motherboard printed circuit
board.
[0036] The metal sheet on which the protrusion for fixing a
semiconductor chip and the through-hole are formed is
surface-treated as required according to known methods to be
oxidized, to form fine concavo-convex shapes and to form a coating
for improving adhesion and electric insulation. In the
surface-treated metal sheet having the protrusion portion and the
clearance hole formed, an insulation portion of a thermosetting
resin composition is formed on all the surfaces thereof other than
the surface on which a semiconductor chip is to be fixed. The
insulation portion of the thermosetting resin composition is formed
by providing prepregs of a thermosetting resin composition in a
semicured state, making a hole having a slightly larger size than
the protrusion portion in the protrusion-corresponding portion of
the prepreg in advance, placing the prepreg on the surface having
the protrusion on which a semiconductor chip is to be directly
fixed, stacking the other prepreg on the other surface of the metal
sheet so as to cover all the surface, and laminate-forming the
resultant set under heat and pressure. The thickness of the prepreg
is arranged to be a little larger than the height of the metal
protrusion. During the heating and pressurizing step, the
thermosetting resin in a semi-cured state, once melted by heat, is
flowed into the clearance hole of the metal sheet to fill in the
clearance hole, and at the same time, the surfaces other than the
metal protrusion portion are integrated with the thermosetting
resin composition.
[0037] Further, the insulation portion may be formed by providing a
solvent-less or solvent-type thermosetting resin composition,
applying the thermosetting resin composition to all the surfaces of
the metal sheet other than the metal protrusion portion by screen
printing, etc., heating the thermosetting resin composition to
bring it into a semicured state, vvthen, placing metal foils on
outer sides and laminate-forming the resultant set under heat and
pressure to integrate the metal foils and the metal sheet. In the
laminate-forming, the resin is flowed into the clearance hole, and
at the same time, the resin is thermally cured. When the resin is
filled in the clearance hole in advance, the resin is applied by
screen printing, etc., flowed into the clearance hole under low
pressure, and a solvent or air is removed by heating, to thermally
cure the resin. When a solvent is contained, the resin is liable to
be insufficiently filled in the clearance hole. A solvent-less
liquid thermosetting resin composition is therefore preferred, and
it is flowed into the clearance hole and cured in advance. Then,
the resin is applied to surfaces other than the exposed metal
portion used for mounting a semiconductor chip, by screen printing,
etc., and heated to bring it into a semicured state. Then, metal
foils are placed on outer sides, and the resultant set is
laminate-formed under heat and pressure. In any method, the
clearance hole of the metal sheet is filled with a thermosetting
resin composition. The side surfaces of the metal sheet may be in
any state where they are coated with the thermosetting resin
composition or exposed.
[0038] For the formation of a through-hole printed circuit board by
a subtractive method, metal foils or single-side copper clad
laminates having a slightly larger size than a printed circuit
board are placed on front and reverse outermost layers, and the
resultant set is laminate-formed under heat and pressure, whereby a
metal-foil-clad multi-layered board having front and reverse
surfaces covered with metal foils for the formation of outer layer
circuits is formed.
[0039] When the laminate-forming is carried out without using metal
foils as the front and reverse layers, a circuit is formed by a
known additive method, to form a printed circuit board.
[0040] In the board prepared by the above subtractive method or
additive method, a hole having a small diameter for a through-hole
for the front and reverse circuit conduction and a hole having a
small diameter for diffusing heat by connection to the metal sheet
are made in portions different from the portion where a
semiconductor is fixed, by a known method using a laser, plasma,
etc.
[0041] The hole for a through-hole for the conduction of front and
reverse signal circuits is formed nearly in the center of the metal
sheet clearance hole filled with the resin, so as not to be in
contact with the metal sheet. Then, a metal layer is formed in the
through-hole by electroless plating or electric plating, to form a
plated through-hole. In a full additive method, wire-bonding
terminals, signal circuits, a pad for a solder ball and conductor
circuits are formed on the front and reverse surfaces
simultaneously.
[0042] In a semi-additive method, the through-hole is plated, and
at the same time, the front and reverse surfaces are also plated.
Then, circuits are formed on the upper and lower surfaces by a
known method.
[0043] In a printed circuit board formed by the laminate-forming
using metal foils on the front and reverse surfaces, metal foil on
the surface of the metal protrusion portion for fixing a
semiconductor chip is also removed at the step of forming circuits
on the front and reverse surfaces. Then, at least the surface of a
wire-bonding pad is plated with a noble metal for wire-bonding,
whereby the printed circuit board is completed. In this case,
portions which require no plating with a noble metal are covered
with a plating resist in advance. Otherwise, after the plating, a
coating of a known thermosetting resin composition or a
photo-selective thermosetting resin composition is formed on the
plated surface as required.
[0044] A semiconductor chip is fixed on the surface of the metal
protrusion portion of the above printed circuit board with an
adhesive or a metal-powder-containing adhesive. Further, the
semiconductor chip and the bonding pad of the printed circuit board
are connected by a wire bonding method, and at least the
semiconductor chip, the bonding wire and the bonding pad are
encapsulated with a known encapsulation resin.
[0045] A solder ball is connected to a solder-ball-connecting
conductor pad on the surface opposite to the semiconductor chip, to
prepare P-BGA, and the solder ball is stacked on a circuit on a
motherboard printed circuit board and melted by heating it for
connection. Otherwise, P-LGA is prepared without adding a solder
ball to the package, and when it is mounted on a motherboard
printed circuit board, a solder-ball-connecting conductor pad
formed on the motherboard printed circuit board surface and a
conductor pad for a solder ball for P-LGA are connected by heating
and melting the solder ball.
[0046] Although not specially limited, the metal sheet for use in
the present invention is preferably selected from those having a
high elastic modulus and a high heat conductivity and having a
thickness of 30 to 300 .mu.m. Specifically, it is preferred to use
pure copper, oxygen free copper, an alloy of copper with Fe, Sn, P,
Cr, Zr, Zn or the like, or a metal sheet prepared by plating an
alloy with copper.
[0047] In the present invention, the protrusion portion preferably
has a height of 30 to 200 .mu.m. Further, the prepreg having a hole
for the protrusion portion or the thermosetting resin formed by
screen printing preferably has a height equal to, or slightly
larger than, the protrusion portion height. The area of the
protrusion portion is sufficient if a semiconductor chip can be
mounted thereon. Generally, it is equal, or slightly larger than,
the area of a semiconductor chip, and it generally has a size
having sides of 5 to 20 mm.
[0048] The resin in the thermosetting resin composition for use in
the present invention is generally selected from known
thermosetting resins. Specific examples thereof include an epoxy
resin, a polyfunctional cyanate ester resin, a polyfunctional
maleimidecyanate ester resin, a polyfunctional maleimide resin and
an unsaturated-group containing polyphenylene ether resin. These
resins are used alone or in combination. In view of heat
durability, humidity durability, anti-migration properties,
electric characteristics after moisture absorption, and the like, a
polyfunctional cyanate ester resin composition is preferred.
[0049] The polyfunctional cyanate ester compound as a preferred
thermosetting resin component in the present invention refers to a
compound whose molecule has at least two cyanato groups.
[0050] Specific examples thereof include 1,3- or
1,4-cyanatobenzene, 1,3,5-tricyanatobenzene, 1,3-, 1,4-, 1,6-,
1,8-, 2,6- or 2,7-dicyanatonaphthalene, 1,3,6tricyanatonaphthalene,
4,4-dicyanatobiphenyl, bis(4dicyanatophenyl)methane,
2,2-bis(4cyanatophenyl)propane,
2,2-bis(3,5-dibromo-4-cyanatophenyl)propa- ne,
bis(4-cyanatophenyl)ether, bis(4-cyanatophenyl)thioether,
bis(4-cyanatophenyl)sulfone, tris(4-cyanatophenyl)phosphite,
tris(4-cyanatophenyl)phosphate and cyanates obtained by a reaction
of novolak with cyan halide.
[0051] Besides the above compounds, there may be used
polyfunctional cyanate ester compounds described in Japanese Patent
Publications Nos. 41 - 1928,43-18468, 44-4791,45- 11721, 46-41112,
4726853 -and 5 1-63 149. Further, aprepolymer having a molecular
weight of 400 to 6,000 and having a triazine ring formed by the
trimerization of a cyanato group of each of these polyfunctional
cyanate ester compounds may be also used. The prepolymer is
obtained by polymerizing the above polyfunctional cyanate ester
monomer in the presence of an acid such as a mineral acid or a
Lewis acid, a base such as sodium alcoolate or a tertiary amine or
a salt such as sodium carbonate as a catalyst. The prepolymer
partly contains an unreacted monomer and is in the form of a
mixture of monomer with prepolymer, and this material is preferably
used in the present invention. Generally, the above resin is
dissolved in an organic solvent in which it is soluble.
[0052] The epoxy resin can be generally selected from known epoxy
resins. Specific examples thereof include a liquid or solid
bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a
phenol novolak type epoxy resin, a cresol novolak type epoxy resin,
an alicyclic epoxy resin, polyepoxy compounds obtained by
epoxidizing the double bond of butadiene, pentadiene,
vinylcyclohexene or cyclopentyl ether, and polyglycidyl compounds
obtained by reacting a polyol, a silcion resin having a hydroxyl
group and epohalohydrin. These resins may be used alone or in
combination.
[0053] The polyimide resin can be generally selected from known
polyimide resins. Examples thereof include reaction products of
functional maleimides and polyamines, and polyimides terminated
with a triple bond, described in JP-B-57-005406.
[0054] The above thermosetting resins may be used alone, while it
is preferred to use a combination thereof as required in view of a
balance of characteristics.
[0055] The thermosetting resin composition used in the present
invention may contain various additives as desired so long as the
inherent properties of the composition are not impaired. Examples
of the additives include monomers containing a polymerizable double
bond such as an unsaturated polyester and prepolymers thereof;
lowmolecular-weight liquid high-molecular-weight elastic rubbers
such as polybutadiene, epoxidized butadiene, maleated butadiene, a
butadiene-acrylonitrile copolymer, polychloroprene, a
butadiene-styrene copolymer, polyisoprene, butyl rubber,
fluorine-containing rubber and natural rubber; polyethylene,
polypropylene, polybutene, poly-4-methylpentene, polystyrene, AS
resin, ABS resin, MBS resin, styrene-isoprene rubber, a
polyeethylene-propylene copolymer,
4-fluoroethylene-6-fluoroethylene copolymer; high-molecular-weight
prepolymers or oligomers of polycarbonate, polyphenylene ether,
polysulfone, polyester and polyphenylene sulfide; and polyurethane.
These additives are used as required. Further, various known
additives such as inorganic or organic filler, a dye, a pigment, a
thickener, a lubricant, an anti-foamer, a dispersing agent, a
leveling agent, a photo-sensitizer, a flame retardant, a
brightener, a polymerization inhibitor and a thixotropic agent may
be used alone or in combination as required. A curing agent or a
catalyst is incorporated into a compound having a reactive group as
required.
[0056] The thermosetting resin composition in the present invention
undergoes curing itself when heated. Since, however, its curing
rate is low, it is poor in economic performances, etc., and a known
heat-curing catalyst is incorporated into the thermosetting resin.
The amount of the catalyst per 100 parts by weight of the
thermosetting resin is 0.005 to 10 parts by weight, preferably 0.01
to 5 parts by weight.
[0057] A known inorganic or organic woven fabric or non-woven
fabric is generally used as a reinforcing substrate for the
prepreg. Specific examples of the reinforcing substrate include
known glass fiber cloths such as E glass, S glass and D glass, a
wholly aromatic polyamide fiber cloth, and a liquid crystal fiber
cloth. These may be mixtures. Further, there may be used a
substrate prepared by applying the thermosetting resin to front and
reverse surfaces of a film such as a polyimide film and bringing it
into a semi-cured state by heating.
[0058] The metal foil used as outermost layers can be generally
selected from known metal foils. Preferably, there is used a copper
foil, an aluminum foil or a nickel foil, each of which has a
thickness of 3 to 100 .mu.m.
[0059] The clearance hole or the slit is made in the metal sheet so
as to have a size slightly larger than the diameter of the
through-hole for the conduction of the front and reverse surfaces.
Specifically, the through-hole wall is insulated with the
thermosetting resin composition such that the thermosetting resin
composition gives a distance of at least 50 .mu.m between the
through-hole wall and the wall of the metal sheet clearance hole or
slit. Although not specially limited, the through-hole for the
front and reverse surface conduction preferably has a diameter of
50 to 300 mm.
[0060] When the prepreg for a multi-layer printed circuit board of
the present invention is prepared, the substrate is impregnated
with the thermosetting resin composition, and the thermosetting
resin composition is dried to obtain a laminating material in a
semicured state. Further, a substrate-free resin sheet prepared in
a semicured state may be used. Otherwise, a coating composition may
be used. In this case, a coating composition is converted to a
high-flow or no-flow material depending upon the degree of a
semi-cured state. When it is converted to a no-flow material, the
flow of the resin after the laminateforming under heat and pressure
is 100 .mu.m or less, preferably 50 .mu.m or less. In this case,
essentially, it bonds to a copper sheet or a copper foil without
causing any voids. The heating temperature the laminate-forming is
generally 100 to 180.degree. C., the time therefor is 5 to 60
minutes, and the temperature and the time are properly selected
depending upon the intended degree of flow.
[0061] In the present invention, there may be employed a structure
in which the inner layer metal sheet to constitute the above
printed circuit board is provided with the protrusion portion of
which the diameter or one side length is 40 to 90% of one side of a
semiconductor chip (FIG. 2, j). The metal-plated through-hole and a
circuit conductor are formed in/on those portions of the printed
circuit board which are different from the metal protrusion portion
immediately below the semiconductor and the circuit conductor of
the through-hole and a heat-conductive adhesive (FIG. 2, k) are
insulated with a heat-curable resist or a photoselective
heat-curable resist. In this case, the semiconductor chip is fixed
to the surface of the metal protrusion portion with a
metal-powder-containing heat-conductive adhesive. There is formed a
structure in which the plated through-hole conductor is formed in a
portion different from the metal protrusion portion below the
semiconductor chip, and the conductor is coated with a heat-curable
resist or a photo-selective heat-curable resist. A heat-conductive
adhesive is applied onto the resist, and a semiconductor chip is
bonded. In this case, differing from a heat-diffusible through-hole
immediately below a conventional gold-plated portion on which a
semiconductor chip is to be mounted, the heat-conductive adhesive
for bonding a semiconductor chip and the circuit or the
through-hole conductor are insulated with a resin composition, and
heat generated by the semiconductor chip is transmitted to the
metal protrusion portion and diffused into a motherboard through
the through-hole (FIG. 2, i) connected directly to the metal sheet.
In FIG. 2,o shows a plating resist.
[0062] In the present invention, as a clearance hole, at least one
slit having a size greater than the diameter of the through-hole
conductor may be made in the inner layer metal sheet which is to
constitute the above printed circuit board. The slit-like clearance
hole is made in the metal sheet so as to have a size slightly
larger than the diameter of the throughhole for the front and
reverse surface conduction. Specifically, the through-hole wall and
the metal sheet slit wall are preferably insulated with the
thermosetting resin composition such that the thermosetting resin
composition gives a distance of at least 50 .mu.m between the
through-hole wall and the wall of the metal sheet slit. Although
not specially limited, the through-hole for the front and reverse
surface conduction preferably has a diameter of 50 to 300 mm.
Further, at least one through-hole formed in the slit is
structurally in direct contact with the metal so that generated
heat is diffused into a motherboard through this heat-diffusible
through-hole. In the above structure, the moisture absorption from
the lower surface below a semiconductor chip does not take place
either, so that the heat durability after moisture absorption is
greatly improved, i.e., that the popcorn phenomenon can be overcome
to a great extent, and that the heat diffusibility is greatly
improved.
[0063] In the present invention, as shown in FIG. 4, there may be
employed a structure in which a signal propagation circuit
conductor on the front (i.e. top) surface of a printed circuit
board and either a signal propagation circuit conductor formed on
the reverse (i.e. bottom) surface of the printed circuit board or a
circuit conductor pad formed for connection to an outside of the
package with a solder ball are connected to each other through a
through-hole conductor via at least one blind via hole (FIG. 4, q).
In the above structure, the moisture absorption from the lower
surface below a semiconductor chip does not take place either, so
that the heat durability after moisture absorption is greatly
improved, i.e., that the popcorn phenomenon can be overcome to a
great extent, and that the heat diffusibility is greatly
improved.
[0064] The process for the production of the metal-sheet-inserted
semiconductor plastic package of the present invention will be
explained below.
[0065] The present invention is directed to a process for the
production of a dual-side, metal-foil-clad laminate for a
semiconductor plastic package structured by disposing an inner
layer metal sheet of nearly the same size as a printed circuit
board, and nearly in the center in the thickness direction of the
printed circuit board, providing at least one exposed metal sheet
protrusion on one surface of the printed circuit board, fixing a
semiconductor chip thereon, connecting the semiconductor chip to a
signal propagation circuit conductor formed on a printed circuit
board surface in the vicinity thereof by wire bonding, at least
connecting the signal propagation circuit conductor on the printed
circuit board surface to a signal propagation circuit conductor
formed on the other surface of the printed circuit board or a
connecting conductor pad of a solder ball with a plated
through-hole conductor, and encapsulating the semiconductor chip
with resin.
[0066] The process comprises the following steps:
[0067] (1) forming a protrusion on one surface of the metal sheet
for mounting the semiconductor chip, and forming a clearance hole
or a slit having a size greater than a diameter of a through-hole,
for providing the through-hole for the conduction of front and
reverse circuit conductors,
[0068] (2) disposing a low-flow or no-flow prepreg sheet or resin
layer having a hole slightly greater than an area of the protrusion
portion on the protrusion position on the side where the metal
protrusion portion is formed, disposing a high-flow prepreg sheet
or resin layer having a resin amount and a resin flow for
sufficiently filling in the clearance hole on the other side, and
disposing metal foils or single-side metal-foil-clad laminates on
both outer sides thereof, and
[0069] (3) laminate-forming the resultant set under heat and under
pressure, preferably in vacuum, to integrate it and form a
metal-core-inserted dual-side metal-foil-clad laminate.
[0070] The above dual-side metal-foil-clad laminate is used to
prepare a printed circuit board, and a semiconductor chip is fixed
with a heat-conductive adhesive such as a silver paste, followed by
wire bonding, encapsulation with a resin and attaching of a solder
ball.
[0071] The above step is carried out as follows.
[0072] (4) A through-hole for front and reverse circuit conduction
is made in a predetermined position with a drill or laser while
keeping the through-hole wall out of contact to the inner layer
metal sheet, and a heat-diffusing through-hole is made so as to
bring it into contact with the metal sheet. The through-holes are
treated for desmearing, followed by plating with a metal. Circuits
are formed on the upper and lower surfaces by a known method, and
preferably, and metal foil on the metal sheet protrusion portion is
removed, followed by plating with a noble metal. A semiconductor
chip is bonded to the protrusion surface of the inner layer metal
sheet with a metal-powder-containing electrically conductive and
thermally conductive adhesive, followed by wire bonding,
encapsulation with a resin and attaching of a solder ball.
[0073] Heat generated by the semiconductor is thermally conducted
to the metal sheet as a whole through the metal portion on which
the semiconductor is directly mounted, so that there is employed a
structure in which at least one plated through-hole is formed so as
to connect to the above metal sheet and a metal pad on the lower
surface so that heat from the semiconductor chip is diffused to a
motherboard printed circuit board.
[0074] In the present invention, the protrusion portion on one
surface of the metal sheet and the clearance hole can be also
formed by the following method.
[0075] (1) First, the entire surface of the metal sheet (FIG. 1, b)
is coated with a liquid etching resist (FIG. 1, a), a solvent is
removed by heating, the resist is covered with a negative film
(FIG. 1, c) prepared so as to leave resist on the protrusion
portion on which a semiconductor chip is to be mounted, the resist
is exposed to ultraviolet light, and an unexposed portion is
dissolved and removed with a solvent such as a 1% sodium carbonate
aqueous solution.
[0076] (2) A predetermined thickness of the metal sheet is
dissolved by etching, and then the etching resist is dissolved and
removed.
[0077] (3) The upper and lower surfaces are again coated with a
liquid etching resist, a negative film having a hole for the metal
protrusion portion is placed on the upper surface, a negative film
prepared so as to shut off light in the clearance hole portion is
placed on the lower surface, and the resultant set is exposed to
ultraviolet light.
[0078] (4) The etching resist in the clearance hole portion is
dissolved and removed, and then both the surfaces are etched by an
etching method, to form the clearance hole (FIG. 1, d).
[0079] In the present invention, a dual-side metal-foilclad
laminate can be also prepared from the above-obtained metal sheet
having the protrusion portion and the clearance hole by the
following method.
[0080] (5) As a prepreg sheet (FIG. 1, f) on a side where the metal
protrusion portion is formed, a low-flow or no-flow prepreg sheet
having a hole slightly greater than the area of the protrusion in a
position of the protrusion, a copper foil with a resin or a resin
layer is provided on the side where the metal protrusion portion is
formed, a high-flow prepreg sheet (FIG. 1, g) having a resin amount
and a resin flow sufficient for being filled in the clearance hole,
a copper foil with a resin or a resin layer is provided on the
other side, and metal foils (FIG. 1, e) having a hole slightly
greater than the metal protrusion portion as required, or
single-side metal-foil-clad laminates are disposed on both the
outer sides.
[0081] (6) The resultant set is laminate-formed under heat and
pressure, preferably in vacuum, to integrate it, whereby there is
formed a metal-core-inserted dual-side metal-foilclad laminate
having the metal protrusion exposed on one surface, which is, for a
semiconductor plastic package.
[0082] In the present invention, a dual-side metal-foil-clad
laminate of which the laminate is a multi-layer laminate can be
also produced by the following method.
[0083] (5) As a prepreg sheet on a side where the metal protrusion
portion is formed, a low-flow or no-flow prepreg sheet having a
hole slightly greater than the area of the protrusion in a position
for the protrusion, a resin sheet or an applied resin layer is
provided on the side where the metal protrusion portion is formed.
A dual-side sheet having a circuit formed on one surface and having
a surface chemically treated as required, or a multi-layer sheet is
placed outside the protrusion portion, a high-flow prepreg sheet
(FIG. 5, g) having a resin amount and a resin flow sufficient for
being filled in the clearance hole, a resin sheet, a copper foil
with a resin or an applied resin layer is provided on the other
surface, and a metal foil (FIG. 5, e) or single-side
metal-foil-clad laminates is disposed thereon.
[0084] (6) The resultant set is laminate-formed under heat and
pressure, preferably in vacuum, to integrate it, whereby there is
formed a metal-core-inserted dual-side metal-foil-clad laminate
having the metal protrusion exposed on one surface, which is for a
semiconductor plastic package.
[0085] The above-produced metal-sheet-inserted dual-side
copper-clad laminate is used as follows.
[0086] (7) a through-hole having a size slightly smaller than the
diameter of the clearance hole conductor is made in the above
metal-sheet-inserted dual-side copper-clad laminate with a drill, a
laser, etc., the hole wall and the metal sheet are insulated with a
resin composition and used as a through-hole (FIG. 1, h) for the
front and reverse circuit conduction, and at least one through-hole
is connected to the metal sheet for use as a through-hole for heat
diffusion and is plated with a metal.
[0087] (8) Then, circuits are formed on the front and reverse
surfaces.
[0088] (9) At least portions other than a bonding pad, a solder
ball pad and the metal protrusion portion on which to mount a
semiconductor chip are coated with a plating resist, and plated
with nickel or gold, to prepare a printed circuit board. A
semiconductor chip (FIG. 1, j) is bonded and fixed to the metal
protrusion portion of the printed circuit board with a
metal-powder-containing electrically conductive or thermally
conductive adhesive (FIG. 1, k), followed by wire bonding (FIG. 1,
l), encapsulation with a resin (FIG. 1, m) and attaching of a
solder ball (FIG. 1, n), whereby a multi-layer semiconductor
plastic package is formed.
[0089] In the present invention, the semiconductor plastic package
having the blind via hole can be produced by the following
procedures after the formation of front and reverse circuits in the
above step (8).
[0090] (9) A hole covering only the semiconductor-chip-mounting
metal exposed portion is made portion is made in the no-flow or
low-flow prepreg with a counter boring machine, the prepreg is
placed on the surface, and a 1 .mu.m thick electrolytic copper foil
is placed thereon.
[0091] (10) The resultant set is integrated by
laminate-formation.
[0092] (11) A copper foil present on a surface portion where via
hole is formed is removed by etching, a via hole (FIG. 4, q) is
formed with a carbon dioxide laser, desmear treatment is carried
out, and the reverse surface is covered with a film, followed by
plating with copper.
[0093] (12) After the front surface is coated with a plating resist
(FIG. 4, o), and a noble metal plating is carried out, a
semiconductor chip (FIG. 4, j) is bonded to the surface of the
protrusion portion which is an inner layer metal sheet portion
where the semiconductor chip is to be mounted with an adhesive
(FIG. 4, k), followed by wire bonding (FIG. 4, i), then encapustion
with a resin (FIG. 4, m) and optional attaching of a solder ball
(FIG. 4, n).
[0094] The present invention also provides a process for
concurrently forming the metal sheet protrusion portion and the
clearance hole by the following procedures.
[0095] An etching resist for forming the protrusion portion is
placed on part of one surface of a metal sheet, an etching resist
for forming the clearance hole or slit by etching is placed on the
other surface, and in an etching step, an etching solution is blown
onto the protrusionportion-forming surface at a lower pressure and
an etching solution is blown onto the other surface at a higher
pressure, whereby the protrusion portion and the clearance hole are
formed at the same time.
[0096] In the present invention, the protrusion portion of the
metal sheet can be formed by the following procedures. That is, a
metal sheet is embossed to form at least one protrusion portion
structured so as to protrude on one surface and have a dent in the
other surface. FIG. 5 shows one protrusion portion formed on a
metal sheet b by embossing, and FIG. 6 shows two protrusion
portions formed on a metal sheet b by embossing.
[0097] In the present invention, as shown in FIG. 7, a protrusion
portion for mounting a semiconductor chip may be formed on one
surface of a metal sheet, and a protrusion for heat diffusion may
be formed on the other surface. Since heat diffused from a
semiconductor is thermally conducted from the portion on which the
semiconductor chip is directly mounted to the metal sheet as a
whole, the heat is diffused through the metal protrusion portion
exposed on the other surface to a motherboard printed circuit
board.
[0098] The above protrusion portions can be formed on both the
surfaces of a metal sheet, e.g., by the following method.
[0099] First, the entire surface of a metal sheet which is to
constitute an inner layer is coated with a liquid etching resist,
the coating is heated to remove a solvent, and a negative film
designed for leaving the protrusion portion on which a
semiconductor chip is to be fixed and the resist on the
reverse-surface protrusion portion for heat diffusion is covered
thereon. This is followed by irradiation with ultraviolet light and
removal of unexposed portion by dissolving. Then, a predetermined
thickness of the metal sheet is etched, and then the etching resist
is removed by dissolving.
[0100] As shown in FIG. 8, the protrusion portion on which a
semiconductor chip is to be mounted may be formed on one surface of
a metal sheet which is to constitute an inner layer, and protrusion
portions may be formed in that portion of the metal sheet which
corresponds to a marginal portion of a printed circuit board such
that the protrusions are exposed on both front and reverse
surfaces. The above protrusion portions on the marginal portion are
provided for diffusing heat. The above protrusion portions on the
metal sheet may be formed by a generally known method such as cold
processing, hot roll profile processing other than the above
etching method. Further, metal sheet(s) of the same or different
quality may be bonded onto a flat smooth metal sheet with an
adhesive such as a copper paste having excellent thermal
conductivity.
[0101] As shown in FIG. 9, the protrusion for mounting a
semiconductor chip may be formed on one surface of a metal sheet
which is to constitute an inner layer, and protrusion portions may
be formed in that portion of the metal sheet which corresponds to a
marginal portion of a printed circuit board such that the
protrusions are exposed on the reverse surface.
[0102] FIG. 10 shows an embodiment in which the protrusion portion
for mounting a semiconductor chip is formed on one surface of a
metal sheet, at least one of a prepreg, a resin sheet, a coating
and a metal foil with a resin is disposed on one of the two
surfaces of the metal sheets, at least one of a prepreg, a resin
sheet, a coating and a metal foil with a resin is disposed on the
other of the two surfaces of the metal sheets, and a metal foil is
disposed on the resin layer having no metal foil. The resultant set
is laminate-formed under heat and pressure to prepare a
metal-foil-clad laminate, and a via hole for heat diffusion is
formed in the metal sheet from the reverse surface so as to reach
the metal sheet. The formed via hole is filled with a metal by
metal plating.
[0103] According to the present invention, there is provided a
semiconductor plastic package which is structured so as to release
generated heat through the metal sheet, which is excellent in heat
diffusibility and is free of absorption of moisture frotn below a
semiconductor chip and which therefore permits a remarkable
decrease in the occurrence of the popcorn phenomenon, and there is
also provided a process for the production thereof. According to
the present invention, further, there are provided a semiconductor
plastic package suitable for mass production and excellent in
economic performance, and a process for the production thereof.
EXAMPLES
[0104] The present invention will be explained more specifically
with reference to Examples hereinafter, in which "part" stands for
"part by weight" unless otherwise specified.
Example 1
[0105] 900 parts of 2,2-bis(4-cyanatophenyl)propane and 100 parts
of bis(4-meleimidephenyl)methane were melted at 150.degree. C. and
allowed to react for 4 hours with stirring, to prepare a
prepolymer. The prepolymer was dissolved in mixed solvents of
methyl ethyl ketone and dimethylformamide. To this were added 400
parts of a bisphenol A type epoxy resin (trade name: Epikote 1001,
supplied by Yuka-Shell Epoxy K.K.) and 600 parts of a cresol
novolak type epoxy resin (trade name: ESCN-220F, supplied by
Sumitomo Chemical Co., Ltd.), and these materials were
homogeneously dissolved and mixed. Further, as a catalyst, 0.4 part
of zinc octylate was added, and these materials were dissolved and
mixed. To the resultant mixture was added 500 parts of an inorganic
filler (trade name: Talc P-3, supplied by Nippon Talc K.K.), and
these materials were homogeneously stirred and mixed to prepare a
varnish A.
[0106] The above varnish was used to impregnate a 100 .mu.m thick
glass woven fabric, and the impregnated glass woven fabric was
dried at 150.degree. C. to prepare a 105 .mu.m thick semi-cured
low-flow prepreg (prepreg B 1) having a gelation time of 0 seconds
at 170.degree. C. and a resin flow of 60 .mu.m at 170.degree. C. at
20 kgf/cm.sup.2 for 5 minutes.
[0107] Further, the same impregnated glass woven fabric was dried
at 145.degree. C. to prepare a 107 .mu.m thick semi-cured high-flow
prepreg (prepreg C1) having a gelation time of 120 seconds at
170.degree. C. and a resin flow of 13 mm.
[0108] On the other hand, an alloy having a thickness of 200 .mu.m
and containing Cu: 97.3%, Fe: 2.5%, P: 0.1%, Zn: 0.07% and Pb:
0.03% was provided for an inner layer metal sheet, and a protrusion
portion having a 13.times.13 mm square size and a height of 100
.mu.m was formed by an etching method so as to be positioned in the
center of a package having a 50.times.50 mm square size.
[0109] Then, a liquid etching resist was applied to the entire
surface of the above metal sheet to form a coating having a
thickness of 25 .mu.m, and the coating was dried to remove the
solvents. A negative film having a hole for the protrusion portion
was placed thereon, and a negative film was placed on the entire
lower side the metal sheet. Portions other than a clearance hole
were exposed to ultraviolet light, and the resist film of a
clearance hole portion was removed with a 1% sodium carbonate
aqueous solution. Then, a clearance hole having a diameter of 0.6
mm was made by etching on both sides.
[0110] The entire surface of the metal sheet was treated to form
black copper oxide, and the above prepreg B having a hole greater
than the protrusion portion by 50 .mu.m made by punching was used
to cover the upper surface thereof. The prepreg C was used to cover
on the lower surface. Electrolytic copper foils having a thickness
of 18 .mu.m were placed on both of the prepregs, and the resultant
set was laminate-formed at 200.degree. C. at 20 kgf/cm.sup.2 at a
vacuum of 30 mmHg or less for 2 hours to integrate them.
[0111] In the clearance hole portion, a through-hole having a
diameter of 0.25 mm was made in the center thereof with a laser so
as not to be brought into contact with the inner layer metal sheet
of the clearance hole portion. Through-holes having a diameter of
0.25 mm each were drilled in four corners so as to be in direct
contact with the metal sheet as heat-diffusible portions. After
desmear treatment, copper plating was carried out by electroless
plating and electric plating to form a 18 pm thick copper plating
layer in the holes.
[0112] A liquid etching resist was applied to the front and reverse
surfaces and dried, and then positive films were placed thereon,
followed by exposure, development and the formation of front and
reverse circuits. At the same time, the copper foil on the
protrusion portion was removed together by etching. A plating
resist was formed on portions other than the protrusion portion, a
bonding pad portion and a ball pad portion, and plating was carried
out with nickel and gold, to complete a printed circuit board.
[0113] A semiconductor chip having a 13.times.13 mm square size was
bonded and fixed to the protrusion portion with a silver paste,
then, wire bonding was carried out. The resultant set was
encapsulated with a silica-containing epoxy-sealing compound by
transfer molding, to obtain a semiconductor package, and solder
balls were attached. The semiconductor package was connected to a
motherboard printed circuit board of an epoxy resin by melting the
solder balls under heat. The resultant semiconductor plastic
package was evaluated, and Table 1 shows the results.
Examples 2
[0114] The same prepreg C1 in Example 1 was provided, a 18 .mu.m
thick electrolytic copper foil was placed on one surface, a release
film was placed on the other surface, and the resultant set was
laminate-formed at 200.degree. C. at 20 kgf/cm.sup.2 for 2 hours to
prepare a single-side copper-clad laminate.
[0115] A rolling copper sheet for an inner layer, having a
thickness of 200 .mu.m, was processed in the same manner as in
Example 1 to form a protrusion having the same size and the same
height as those in Example 1. Further, a clearance hole having a
diameter of 0.6 mm was made, prepregs were similarly placed on the
upper and lower surfaces, sheets of the above-obtained single-side
coppers clad laminate were placed on both sides, and the resultant
set was laminate-formed under the same conditions.
[0116] In the clearance hole portion, a through-hole having a
diameter of 0.20 mm was drilled in the center thereof so as not to
be brought into the metal sheet of the clearance hole portion.
Through-holes were drilled in four corners so as to be in direct
contact with the metal sheet as heat-diffusible portions. After
desmear treatment, copper plating was carried out by electroless
plating and electric plating to form a 17 .mu.m thick copper
plating layer in the holes.
[0117] A liquid etching resist was applied to the front and reverse
surfaces and dried to remove the solvents, and then positive films
were placed thereon, followed by exposure, development and the
formation of front and reverse circuits. A plating resist was
formed on portions other than the laminate portion on the
protrusion portion, a bonding pad portion and a ball pad portion,
plating was carried out with nickel and gold, and then the
substrate of the laminate portion on the central copper sheet
protrusion portion was removed by cutting with a router, to
complete a printed circuit board.
[0118] Then, a semiconductor was bonded and followed by
encapsulation with a resin in the same manner as in example 1, to
form a semiconductor plastic package. The resultant semiconductor
plastic package was evaluated, and Table 1 shows the results.
Comparative Example 1
[0119] Two sheets of prepregs which were the same as the high-flow
prepreg C1 in Example 1 were used. Electrolytic copper foils were
placed on upper and lower surfaces thereof, and the resultant set
was laminate-formed at 190.degree. C. at 20 kgf/cm.sup.2 under
vacuum for 90 minutes, to obtain a dual-side copper-clad laminate.
A through-hole having a diameter of 0.25 mm was drilled in a
predetermined position, and copper plating was carried out.
[0120] Circuits were formed on the upper and lower surfaces of the
above laminate according to a known method, and nickel plating and
gold plating were carried out. The through-hole for heat diffusion
was formed in a portion where a semiconductor chip was to be
mounted, a semiconductor chip was bonded thereon with a silver
paste, and wire bonding was carried out, followed by encapsulation
with a liquid sealing resin (FIG. 11). Solder balls were attached
thereto, and the package was connected to a motherboard. The
resultant semiconductor plastic package was evaluated, and Table 1
shows the results.
Comparative Example 2
[0121] The printed circuit board obtained in Comparative Example 1
was bored in a portion where the semiconductor chip was mounted,
and then, a 200 .mu.m thick copper sheet was bonded to the reverse
surface thereof with a prepreg prepared by punching the above no.
flow prepreg under heat and pressure, to prepare a
heat-diffusing-sheet-attached printed circuit board.
[0122] The above printed circuit board was slightly distorted. A
semiconductor chip was bonded to the above heat-diffusing sheet
with a silver paste, followed by wire bonding and encapsulation
with a liquid sealing resin (FIG. 12). The resultant semiconductor
plastic package was evaluated, and Table 1 shows the results.
[0123] Measurement methods in Examples including Examples to be
described later were as shown below.
[0124] 1) Heat resistance after moisture absorption {circle over
(1)}: JEDEC STANDARD TEST METHOD A 113-A LEVEL 3: After treatment
at 30.degree. C. at 60% RH for a predetermined period of time, and
after 3 cycles of 220.degree. C. reflow soldering, a substrate was
evaluated for failures by observing its cross section and electric
checking.
[0125] 2) Heat resistance after moisture absorption {circle over
(2)}: JEDEC STANDARD TEST METHOD A 113-A LEVEL 2: After treatment
at 85.degree. C. at 60% RH for a predetermined period of time (max.
168 hours), and after 3 cycles of 220.degree. C. reflow soldering,
a substrate was evaluated for failures by observing its cross
section and electric checking.
[0126] 3) Glass transition temperature: Measured by DMA method.
[0127] 4) Insulation resistance value after treatment with pressure
cooker: A sample was treated at 121.degree. C. under two
atmospheric pressures for a predetermined period of time and then
treated at 25.degree. C. at 60% RH for 2 hours, and then while 500
VDC was applied for 60 seconds, an insulation resistance value
between terminals (line/space=70 .mu.m/70 .mu.m) was measured.
[0128] 5) Migration resistance: At 85.degree. C. and at 85% RH, 500
VDC was applied, and an insulation resistance value between
terminals was measured.
1 TABLE 1 Example 1 Example 2 CEx. 1 CEx. 2 Heat Ordinary No
failure No failure No failure No resistance state failure after 48
hours No failure No failure No failure No failure moisture 96 hours
No failure No failure No failure No failure absorption{circle over
(1)} 120 hours No failure No failure No failure No failure 144
hours No failure No failure Partly No peeled off failure 168 hours
No failure No failure Partly Partly peeled off peeled off Heat
Ordinary No failure No failure No failure No resistance state
failure after 24 hours No failure No failure Partly No moisture
peeled off failure absorption{circle over (2)} 48 hours No failure
No failure Largely Partly peeled off peeled off 72 hours No failure
No failure Largely Largely peeled off peeled off 96 hours No
failure No failure Wire ditto broken 120 hours No failure No
failure -- Wire broken 144 hours No failure No failure -- -- 168
hours No failure Partly -- -- peeled off Tg (.degree. C.) 234 -- --
-- Insulation Ordinary 5 .times. 10.sup.11 -- -- -- resistance
state (.OMEGA.) after 200 hours 3 .times. 10.sup.12 pressure 500
hours 4 .times. 10.sup.11 cooker 700 hours 7 .times. 10.sup.10 test
1000 hours 1 .times. 10.sup.10 Migration Ordinary 6 .times.
10.sup.13 -- -- -- resistance, state (.OMEGA.) 200 hours 6 .times.
10.sup.11 500 hours 3 .times. 10.sup.11 700 hours 7 .times.
10.sup.10 1000 hours 6 .times. 10.sup.10 CEx. = Comparative Example
Tg = Glass transition temperature
Example 3
[0129] A varnish A was prepared in the same manner as in Example 1.
A glass woven fabric having a thickness of 100 .mu.m was
impregnated with the above varnish A and dried at 150.degree. C. to
prepare a 105 .mu.m thick semi-cured low-flow prepreg (prepreg B2)
having a gelation time of 7 seconds at 170.degree. C. and a resin
flow of 110 .mu.m at 170.degree. C. at 20 kgf/cm.sup.2 for 5
minutes. Further, there was also prepared a 109 .mu.m thick
high-flow prepreg (prepreg C2) having a gelation time of 114
seconds and a resin flow of 13 mm.
[0130] A copper sheet having a thickness of 250 .mu.m, which was to
constitute an inner layer, was provided. A liquid etching resist
was applied to the entire surface of the metal sheet to form a
coating having a thickness of 20 .mu.m, and the coating was dried
to remove the solvents. Then, on the surface, the etching resist
was left so as to leave a protrusion portion having a 8.times.8 mm
square size in the center of the metal sheet having a 50.times.50
mm square size, and on the reverse surface, the etching resist was
left on its entire surface, and only the upper surface of the
copper sheet was etched to form a protrusion portion having a
squaresize area of 8.times.8 mm and a height of 100 .mu.m for
mounting a semiconductor chip. After the removal of the etching
resist, a liquid etching resist was again applied to form a coating
having a thickness of 20 .mu.m, and the coating was dried. A
negative film having a hole made for the metal protrusion portion
was used to cover the surface, a negative film having no hole was
used to cover the reverse surface, and after irradiation with
ultraviolet light, resist film in a clearance hole portion was
removed with a 1% sodium carbonate aqueous solution. Then, a
clearance hole having a diameter of 0.6 mm was made by etching on
both the surfaces.
[0131] Then, the entire surface of the metal sheet was treated to
form black copper oxide, and the above prepreg B having a hole
greater than the protrusion portion by 50 .mu.m 5 made by punching
was covered on the upper surface thereof. The prepreg C was covered
on the lower surface, electrolytic copper foils having a thickness
of 12 .mu.m were placed on both of them, and the resultant set was
laminate-formed at 200.degree. C. at 20 kgf/cm.sup.2 at a vacuum of
30 mmHg or 10 less for 2 hours to integrate them.
[0132] In the clearance hole portion, a through-hole having a
diameter of 0.25 mm was drilled in the center thereof so as not to
be brought into contact with the metal sheet of the clearance hole
portion. Four heat-diffusing through-holes were drilled in four
corners so as to be in direct contact with the metal sheet. After
desmear treatment, copper plating was carried out by electroless
plating and electric plating to form a 17 .mu.m thick copper
plating layer in the holes.
[0133] A liquid etching resist was applied to the front and reverse
surfaces and dried, and then positive films were placed thereon,
followed by exposure, development and the formation of front and
reverse circuits. At the same time, the copper foil on the
protrusion portion were removed together by etching. A plating
resist was formed on portions other than the protrusion portion, a
bonding pad portion and a ball pad portion, and plating was carried
out with nickel and gold, to complete a printed circuit board. A
semiconductor chip having a 13.times.13 mm square size was bonded
and fixed to the protrusion portion with a silver paste, then, wire
bonding was carried out, the resultant set was encapsulated with an
epoxyresin-based sealing compound, to obtain a semiconductor
package, and solder balls were attached. The semiconductor package
was connected onto a motherboard. The resultant semiconductor
plastic package was evaluated, and Table 2 shows the results.
Example 4
[0134] One prepreg sheet which is the same as the prepreg C1 in
Example 1 was used. A 18 .mu.m electrolytic 10 copper foil was
placed on one surface, a release film was placed on the other
surface, and the resultant set was laminate-formed at 200.degree.
C. at 20 kgf/cm.sup.2 at a vacuum of 30 mmHg or less, to obtain a
single-side copper-clad laminate. An alloy sheet containing Cu:
99.86 wt %, Fe: 0.11 wt % and P: 0.03 wt % was prepared and
processed in the same manner as in Example 3 to form a protrusion
portion having an area of 5.times.5 mm square size and a height of
100 .mu.m. A clearance hole was made in the same manner. Then, the
above prepreg B having a hole for the metal protrusion 20 portion
was placed on the upper surface, the above prepreg C was placed on
the lower surface, the above single-side copper-clad laminate was
placed on an outside thereof, and the resultant set was
laminate-formed. Then, a printed circuit board was prepared. In the
clearance hole portion, a through-hole having a diameter of 0.20 mm
was drilled in the center thereof so as not to be brought into
contact with the metal sheet of the clearance hole portion. Heat
diffusing through-holes were drilled so as to be in contact with
the metal sheet. After desmear treatment, copper plating was
carried out by electroless plating and electric plating to form a
18 .mu.m thick copper plating layer in the holes.
[0135] A liquid etching resist was applied to the front and reverse
surfaces and dried to remove the solvents, and then positive films
were placed thereon, followed by exposure and development to form
front and reverse circuits. A plating resist was formed on portions
other than the protrusion portion for mounting a semiconductor
chip, a bonding pad portion and a ball pad portion, and plating was
carried out with nickel and gold. Substrate on the upper side of
the metal protrusion portion was removed by cutting with a router
to complete a printed circuit board. A semiconductor chip was
bonded thereto with a silver paste, then, wire bonding was carried
out. The resultant set was encapsulated with a resin and solder
balls were attached, to obtain a semiconductor package. The
semiconductor package was connected to a motherboard in the same
manner as in Example 3. The resultant semiconductor plastic package
was evaluated, and Table 2 shows the results.
Comparative Example 3
[0136] 500 parts of an epoxy resin (trade name: Epikote 1045), 500
parts of an epoxy resin (trade name: ESCN220F), 300 parts of
dicyandiamide and 2 parts of 2-ethylimidazole were dissolved in
mixed solvents of methyl ethyl ketone and dimethylformamide, the
resultant solution was used to impregnate a 100 .mu.m thick glass
woven fabric, to prepare a no-flow prepreg (prepreg D) having a
gelation time of 10 seconds at 170.degree. C. and a resin flow of
98 .mu.m and a high-flow prepreg (prepreg E) having a gelation time
of 150 seconds and a resin flow of 18 mm. Two sheets of the prepreg
E were used, and a single-side copper-clad laminate was prepared by
laminate-formation at 170.degree. C. at 20 kgf/cm.sup.2 at a vacuum
of 30 mmHg for 2 hours. Thereafter, a printed circuit board was
prepared in the same manner as in Comparative Example 1. A portion
for mounting a semiconductor chip was bored with a boring machine,
a 200 .mu.m thick copper sheet was similarly bonded to the reverse
surface with a prepreg prepared by punching out the above no-flow
prepreg D, under heat and pressure, to a
heat-diffusing-sheet-attached printed circuit board. This board
caused distortion to some extent. A semiconductor chip was directly
bonded to the above heat-diffusing sheet with a silver paste,
followed by wire bonding connection and encapsulation with a liquid
epoxy resin. Solder balls were attached to the surface opposite to
the metalattached surface. The resultant semiconductor plastic
package was similarly connected to a motherboard. The semiconductor
plastic package was evaluated, and Table 2 shows the results.
2 TABLE 2 Example 3 Example 4 CEx. 1-2 CEx. 3 Heat Ord. state No
failure No failure No failure No failure resistance After 24 hours
No failure No failure No failure No failure moisture 48 hours No
failure No failure No failure No failure absorp- 72 hours No
failure No failure No failure No failure tion{circle over (1)} 96
hours No failure No failure No failure Partly peeled 120 hours No
failure No failure Partly Partly peeled off peeled 144 hours No
failure No failure Partly Partly peeled off peeled 168 hours No
failure No failure Partly Partly peeled off peeled Heat Ord. state
No failure No failure No failure No failure resistance After 24
hours No failure No failure Partly Partly moisture peeled off
peeled absorp- 48 hours No failure No failure Largely Largely
tion{circle over (2)} peeled off peeled 72 hours No failure No
failure Wire Wire broken broken 96 hours No failure No failure Wire
Wire broken broken 120 hours No failure No failure Wire Wire broken
broken 144 hours No failure NO failure -- -- 168 hours No failure
Partly -- -- peeled off Tg (.degree. C.) 234 235 234 145 Insulation
Ord. state 6 .times. 10.sup.11 7 .times. 10.sup.11 4 .times.
10.sup.11 6 .times. 10.sup.11 resistance 200 hours 6 .times.
10.sup.12 4 .times. 10.sup.12 5 .times. 10.sup.12 2 .times.
10.sup.9 (.OMEGA.) after 500 hours 4 .times. 10.sup.11 2 .times.
10.sup.11 1 .times. 10.sup.11 <10.sup.9 pressure 700 hours 4
.times. 10.sup.10 4 .times. 10.sup.10 3 .times. 10.sup.10 -- cooker
1000 hours 2 .times. 10.sup.10 1 .times. 10.sup.10 8 .times.
10.sup.9 -- test Migration Ord. state 5 .times. 10.sup.10 6 .times.
10.sup.12 6 .times. 10.sup.12 6 .times. 10.sup.12 resistance 200
hours 5 .times. 10.sup.11 5 .times. 10.sup.11 5 .times. 10.sup.11 7
.times. 10.sup.9 (.OMEGA.) 500 hours 4 .times. 10.sup.11 3 .times.
10.sup.11 2 .times. 10.sup.11 <10.sup.9 700 hours 1 .times.
10.sup.11 2 .times. 10.sup.11 1 .times. 10.sup.11 -- 1000 hours 9
.times. 10.sup.10 8 .times. 10.sup.10 7 .times. 10.sup.9 -- Heat
(.degree. C.) 35 36 57 48 diffus- ibilty CEx. = Comparative Example
Ord. state = Ordinary state Tg = Glass transition temperature
Example 5
[0137] A varnish A was prepared in the same manner as in Example
1.
[0138] A 100 .mu.m thick glass woven fabric was impregnated 5 with
the varnish A, and the varnish A was dried at 150.degree. C. to
give a 105 .mu.m thick semi-cured (prepreg B3) having a gelation
time of 6 seconds at 170.degree. C. and a resin flow of 110.mu.m at
170.degree. C. at 20 kg f/cm.sup.2/for 5 minutes.) Further, there
was also prepared a 109 .mu.m thick prepreg (prepreg C2) having a
10 gelation time of 114 seconds and a resin flow of 13 mm.
[0139] On the other hand, a copper sheet having a thickness of 250
.mu.m was prepared for an inner layer metal sheet, and a protrusion
portion having a 13.times.13 mm square size and a height of 100
.mu.m was formed by an etching method so as to be positioned in the
center of a package having a 50.times.50 mm square size.
[0140] Then, a liquid etching resist was applied to the entire
surface of the above metal sheet to form a coating having a
thickness of 20 .mu.m, and the coating was dried to remove the
solvents. Negative films having a hole for the protrusion portion
were placed on both sides. Portions other than a slit portion were
exposed to ultraviolet light, and the resist film of the slit
portion was removed with a 1% sodium carbonate aqueous solution.
Then, a slit having a width of 0.6 mm and a length of 10 mm was
made by etching on both sides.
[0141] The entire surface of the metal sheet was treated to form
black copper oxide, and a BT resin solvent-free hole-filling resin
(trade name: BT S730, supplied by Mitsubishi Gas Chemical Co.,
Inc.) was filled in the above slit portion, and thermally cured at
120.degree. C. for 40 minutes and at 160.degree. C. for 60
minutes.
[0142] The above prepreg B has a hole which was made by a router
and is greater than the protrusion portion by 50 .mu.m was used to
cover the upper surface thereof. The prepreg C was used to cover
the lower surface, electrolytic opper foils having a thickness of
18 .mu.m were placed on both of them, and the resultant set was
laminate-formed at 200.degree. C. at 20 kgf/cm.sup.2 at a vacuum of
30 mmHg or less for 2 hours to integrate them.
[0143] In the slit portion, a through-hole having a diameter of
0.25 mm was drilled in the center thereof so as not to be brought
into contact with the metal of the slit portion. Through-holes for
heat diffusion were drilled in four corners so as to be in direct
contact with the inner layer metal sheet. After desmear treatment,
copper plating was carried out by electroless plating and electric
plating to form a 17 .mu.m thick copper plating layer in the holes.
A liquid etching resist was applied to the front and reverse
surfaces and dried, and then positive films were placed thereon,
followed by exposure and development to form front and reverse
circuits. At the same time, the copper foil on the protrusion
portion were removed together by etching, to give a printed circuit
board. Then, plating was carried out with nickel and gold, to
complete the printed circuit board.
[0144] A semiconductor chip having a 13.times.13 mm square size was
bonded and fixed to the upper-surface protrusion portion with a
silver paste. Then, wire bonding was carried out, and the
semiconductor chip, wires and a bonding pad portion were
encapsulated with a silica-containing epoxy-sealing compound by
transfer molding, to obtain a semiconductor package. The resultant
semiconductor package was evaluated, and the Table 3 shows the
results.
[0145] The above prepreg B has a hole which was made by a router
and is greater than the protrusion portion by 50 .mu.m was used to
cover the upper surface thereof. The prepreg C was used to cover
the lower surface, electrolytic copper foils having a thickness of
18 .mu.m were placed on both of them, and the resultant set was
laminate-formed at 200.degree. C. at 20 kgf/cm.sup.2 at a vacuum of
30 mmHg or less for 2 hours to integrate them.
[0146] In the slit portion, a through-hole having a diameter of
0.25 mm was drilled in the center thereof so as not to be brought
into contact with the metal of the slit portion. Through-holes for
heat diffusion were drilled in four corners so as to be in direct
contact with the inner layer metal sheet. After desmear treatment,
copper plating was carried out by electroless plating and electric
plating to form a 17 .mu.m thick copper plating layer in the holes.
A liquid etching resist was applied to the front and reverse
surfaces and dried, and then positive films were placed thereon,
followed by exposure and development to form front and reverse
circuits. At the same time, the copper foil on the protrusion
portion were removed together by etching, to obtain a printed
circuit board. Then, plating was carried out with nickel and gold,
to complete the printed circuit board.
[0147] A semiconductor chip having a 13.times.13 mm square size was
bonded and fixed to the upper-surface protrusion portion with a
silver paste. Then, wire bonding was carried out, and the
semiconductor chip, wires and a bonding pad portion were
encapsulated with a silica-containing epoxy-sealing compound by
transfer molding, to obtain a semiconductor package. The resultant
semiconductor package was evaluated, and Table 3 shows the
results.
Example 6
[0148] A prepreg which is the same as the prepreg C1 in Example 1
was used. A 18 .mu.m electrolytic copper foil was 5 placed on one
surface, a release film was placed on the other surface, and the
resultant set was laminate-formed at 200.degree. C. at 20
kgf/cm.sup.2 for 2 hours to obtain a single-side copper-clad
laminate.
[0149] An alloy sheet containing Cu: 99.86 wt %, Fe: 0.11 wt % and
P: 0.03 wt % was provided for an inner layer, and it was processed
in the same manner as in Example 5 to form two protrusion portions
having a 10.times.10 mm square size and a height of 100 .mu.m.
[0150] Further, a slit was made in the same manner as in Example 5.
Then, the slit was filled with a resin, the prepreg B3 having holes
made with a router for the protrusion portions was placed on the
upper surface, the prepreg C2 was placed on the lower surface, the
above obtained single-side copper-clad laminate sheets were placed
on both sides, and the resultant set was laminate-formed in under
the same conditions.
[0151] In the slit portion, a through-hole having a diameter of
0.20 mm was drilled in the center thereof so as not to be brought
into contact with the metal of the slit portion. After desmear
treatment, copper plating was carried out by electroless plating
and electric plating to form a 17 .mu.m thick copper plating layer
in the hole. A plating resist was formed on portions other than
laminate sheet portions on the protrusion portions, a bonding pad
and a ball pad portion. The plating was carried out with nickel and
gold. The substrate of the laminate sheet portion on the central
copper sheet protrusion portion was removed by cutting with a
router, to complete a printed circuit board. Then, similarly, a
semiconductor chip was bonded, and then wire bonding was carried
out, followed by encapsulation with a resin, to obtain a
semiconductor package. The resultant semiconductor package was
evaluated, and Table 3 shows the results.
3 TABLE 3 Example 5 Example 6 Heat Ordinary state No failure No
failure resistance 96 hours No failure No failure after moisture
120 hours No failure No failure absorption{circle over (1)} 144
hours No failure No failure 168 hours No failure No failure Heat
Ordinary state No failure No failure resistance 24 hours No failure
No failure after moisture 48 hours No failure No failure
absorption{circle over (2)} 72 hours No failure No failure 96 hours
No failure No failure 120 hours No failure No failure 144 hours No
failure No failure 168 hours No failure Partly peeled off Tg
(.degree. C.) 234 -- Insulation Ordinary state 6 .times. 10.sup.11
-- resistance 200 hours 5 .times. 10.sup.12 (.OMEGA.) after 500
hours 4 .times. 10.sup.11 pressure 700 hours 6 .times. 10.sup.10
cooker test 1000 hours 3 .times. 10.sup.10 Migration Ordinary state
4 .times. 10.sup.10 -- resistance 200 hours 5 .times. 10.sup.11
(.OMEGA.) 500 hours 5 .times. 10.sup.11 700 hours 8 .times.
10.sup.10 1000 hours 3 .times. 10.sup.10 Heat (.degree. C.) 38 39
diffusibilty Tg = Glass transition temperature
Example 7
[0152] A varnish A was prepared in the same manner as in Example 1.
The varnish A was used to prepare a prepreg (prepreg B) which was
the same as the prepreg B in Example 1. Further, there was also
prepared a 109 .mu.m thick prepreg C having a gelation time of 114
seconds and a reflow flow of 13 mm.
[0153] A 250 .mu.m thick copper sheet was provided for an inner
layer metal sheet, and one protrusion having a 13.times.13 mm
square size and a height of 100 .mu.m was formed so as to be
present in the center of a package having a 50.times.50 mm square
size.
[0154] A liquid etching resist was applied to the entire surface of
the above metal sheet to form a coating having a 15 thickness of 20
.mu.m, and a clearance hole having a diameter of 0.6 mm was made in
the same manner as in Example 1.
[0155] The entire surface of the metal sheet was treated to form
black copper oxide, the prepreg B, the prepreg C and electrolytic
copper foils were laminate-formed and integrated in the same manner
as in Example 1.
[0156] Then, a through-hole was made in the same manner as in
Example 1, and a 17 .mu.m thick copper plating layer was formed in
the hole.
[0157] A liquid etching resist was applied to the front and reverse
surfaces and dried, and positive films were placed thereon,
followed by exposure and development to form front and reverse
circuits. At the same time, copper foil on the protrusion portion
was concurrently removed by etching, to form a printed circuit
board. Then, a hole which was 100 .mu.m greater than the protrusion
portion metal of the surface exposed metal portion, used for fixing
a semiconductor chip, was made with a router, to prepare a prepreg
B1. The prepreg B1 was placed on the above printed circuit board, a
18 .mu.m thick electrolytic copper foil was also placed, and the
resultant set was laminate-formed at 200.degree. C. at 20
kgf/cm.sup.2 under vacuum.
[0158] Copper foil in a portion where a blind via hole was to be
made was removed by etching, a hole was made with a carbon dioxide
gas laser, and after desmear treatment, copper plating was carried
out in the same manner as in Example 1. A plating resist was formed
on portions other than the protrusion portion, a bonding pad and a
ball pad, and plating with nickel and gold was carried out to
complete the printed circuit board.
[0159] A semiconductor chip having a 13.times.13 mm square size was
bonded and fixed to the above protrusion portion with a silver
paste, wire bonding was carried out, and the semiconductor chip was
encapsulated with a silica-containing epoxy sealing liquid resin,
to obtain a semiconductor package. The resultant semiconductor
package was evaluated, and the Table 4 shows the results.
[0160] Example 8
[0161] A prepreg C1 was used, and a single-side copperclad laminate
was prepared in the same manner as in Example 1.
[0162] An alloy having a thickness of 250 .mu.m and containing Cu:
99.86 wt %, Fe: 0.11 wt % and P: 0.03 wt %, which was to constitute
an inner layer, was processed in the same manner as in Example 1,
to form two protrusions having a 10.times.10 mm square size and a
height of 100 .mu.m on the surface.
[0163] Further, a clearance hole having a diameter of 0.6 mm was
made, prepreg B1 having holes made for the protrusion portions with
a router was similarly placed on the front surface, prepreg C1 was
placed on the reverse surface, and two sheets of the above-obtained
single-side copper-clad laminate were placed on both sides, and the
resultant set was laminate-formed under the same conditions.
[0164] In the clearance hole portion, a through-hole having a
diameter of 0.20 mm was drilled in the center thereof so as not to
be brought into contact with the metal of the clearance hole
portion. After desmear treatment, copper plating was carried out by
electroless plating and electric plating to form a 17 .mu.m thick
copper plating layer in the hole.
[0165] An etching resist was applied to the front and reverse
surfaces and dried to remove the solvents, and then positive films
were placed, followed by exposure and development, to form front
and reverse circuits.
[0166] Then, laminate-formation was carried out with the prepreg B1
in the same manner as in Example 1, a via hole portion was
similarly made, a plating resist was formed on portions other than
laminate sheet portions on the protrusion portions, a bonding pad
portion and a ball pad portion. Plating with nickel and gold was
carried out, and substrate of the laminate sheet portions on the
central copper sheet protrusion portions were removed with a
router, to complete a printed circuit board. Then, similarly, a
semiconductor chip was bonded, followed by wire bonding and
encapsulation with a resin, to obtain a semiconductor package. The
resultant semiconductor package was evaluated, and Table 4 shows
the results.
4 TABLE 4 Example 7 Example 8 Heat Ordinary state No failure No
failure resistance 96 hours No failure No failure after moisture
120 hours No failure No failure Absorption{circle over (1)} 144
hours No failure No failure 168 hours No failure No failure Heat
Ordinary state No failure No failure resistance 24 hours No failure
No failure after moisture 48 hours No failure No failure
absorption{circle over (2)} 72 hours No failure No failure 96 hours
No failure No failure 120 hours No failure No failure 144 hours No
failure Partly peeled off 168 hours No failure Partly peeled off Tg
(.degree. C.) 234 -- Insulation Ordinary state 4 .times. 10.sup.11
-- resistance 200 hours 6 .times. 10.sup.12 (.OMEGA.) after 500
hours 6 .times. 10.sup.12 pressure 700 hours 5 .times. 10.sup.10
cooker test 1000 hours 2 .times. 10.sup.10 Migration Ordinary state
5 .times. 10.sup.13 -- resitance 200 hours 6 .times. 10.sup.11
(.OMEGA.) 500 hours 5 .times. 10.sup.11 700 hours 9 .times.
10.sup.10 1000 hours 6 .times. 10.sup.10 Heat (.degree. C.) 37 38
diffusibilty Tg = Glass transition temperature
Example 9
[0167] A varnish A was prepared in the same manner as in Example 1.
The varnish A was used to impregnate a 100 .mu.m thick glass woven
fabric and dried at 150.degree. C. to obtain a 105 .mu.m thick
semi-cured low-flow prepreg (prepreg B2) having a gelation time of
7 seconds at 170.degree. C. and a resin flow of 110 .mu.m at
170.degree. C. at 20 kgf/cm.sup.2 for 5 minutes. Further, the same
impregnated glass woven fabric was dried at 145.degree. C. to
obtain a 107 .mu.m thick high-flow prepreg (prepreg C1) having a
gelation time of 120 seconds at 170.degree. C. and a resin flow of
13 mm.
[0168] The same metal sheet as that in Example 1 was prepared, and
a protrusion portion having a 13.times.13 mm square size and a
height of 100 .mu.m was formed by an etching method so as to be
positioned in the center of a package having a 50.times.50 mm
square size. Then, a clearance hole having a diameter of 0.6 mm was
made in the same manner as in Example 1. The entire surface of the
metal sheet was treated to form black copper oxide, and the above
prepreg B2 having a hole greater than the protrusion portion by 50
.mu.m made by punching in a position corresponding to the
protrusion portion was covered on the upper surface thereof. The
prepreg C1 was covered on the lower surface, electrolytic copper
foils having a thickness of 12 .mu.m were placed on both of them,
and the resultant set was laminate-formed at 200.degree. C. at 20
kgf/cm.sup.2 at a vacuum of 30 mmHg or less for 2 hours to
integrate them, whereby a dual-side copper-clad laminate was
obtained. In the clearance hole portion, a through-hole having a
diameter of 0.25 mm was made in the center thereof with a laser so
as not to be brought into contact with the metal sheet of the
clearance hole portion. Four heat-diffusing through-holes having a
diameter of 0.25 mm were made in four corners with a laser so as to
be in direct contact with the metal sheet. After desmear treatment,
copper plating was carried out by electroless plating and electric
plating to form a 18 .mu.m thick copper plating layer in the
holes.
[0169] A liquid etching resist was applied to the front and reverse
surfaces and dried, and then positive films were placed thereon,
followed by exposure and development and the formation of front and
reverse circuits. At the same time, the copper foil on the
protrusion portion were removed together by etching. A plating
resist was formed on portions other than the protrusion portion, a
bonding pad portion and a ball pad portion, and plating was carried
out with nickel and gold, to complete a printed circuit board.
[0170] A semiconductor chip having a 13.times.13 mm square size was
bonded and fixed to the protrusion portion with a silver paste,
then, wire bonding was carried out, the resultant set was
encapsulated with a silica-containing epoxy sealing compound by
transfer molding, and solder balls were attached, to obtain a
semiconductor package. The semiconductor package was connected to
an epoxy resin motherboard printed circuit board by melting the
solder balls. The semiconductor plastic package was evaluated, and
Table 5-shows the results.
Example 10
[0171] The same prepreg C1 in Example 1 was provided, a 12 .mu.m
thick electrolytic copper foil was placed on one surface of the
prepreg, a release film was placed on the other surface, and the
resultant set was laminate-formed at 200.degree. C. at 20
kgf/cm.sup.2 for 2 hours to prepare a single-side copper-clad
laminate. A rolling copper sheet having a thickness of 200 .mu.m,
which was to constitute an inner layer, was processed in the same
manner as in Example 1 to form a protrusion having the same size
and the same height as those in Example 1. Further, a clearance
hole having a diameter of 0.6 mm was made. The same varnish A as
that in Example 1 was applied to the front and reverse surfaces by
screen printing such that no resin adhered to the metal protrusion
portion, and formed coatings were dried. The above application and
the drying were alternately repeated three times each, to form a
resin layer having a thickness of 105 .mu.m. The resin layer on the
front surface was adjusted to be in a low-flow state and had a
gelation time of 5 to 10 seconds at 170.degree. C., and the resin
layer on the reverse surface was adjusted to be in a high-flow
state and had a gelation time of 60 to 70 seconds. The
above-obtained single-side copper-clad laminate sheets were placed
on both sides thereof, and the resultant set was laminate-formed
under the same conditions, to prepare a dual-side copper-clad
laminate. In the clearance hole portion, a through-hole having a
diameter of 0.20 mm was drilled in the center thereof so as not to
be brought into the metal sheet of the clearance hole portion.
Through-holes were similarly drilled in four corners so as to be in
direct contact with the metal sheet as heat-diffusible portions.
After desmear treatment, copper plating was carried out by
electroless plating and electric plating to form a 17 .mu.m thick
copper plating layer in the holes. A liquid etching resist was
applied to the front and reverse surfaces and dried to remove the
solvents, and then positive films were placed thereon, followed by
exposure and development to form front and reverse circuits. A
plating resist was formed on portions other than the laminate
portion on the protrusion portion, a bonding pad and a ball pad.
The plating was carried out with nickel and gold, and then the
substrate of the laminate portion on the central copper sheet
protrusion portion was removed by cutting with a router, to
complete a printed circuit board. The flowing of resin into the top
of the metal protrusion portion removed by cutting with the router
was found to be 20 .mu.m or less. Further, the cross section of the
clearance hole was found to be free of voids.
[0172] Then, a semiconductor was similarly bonded and followed by
encapsulation with a resin, to form a semiconductor plastic
package. The semiconductor package was similarly connected to an
epoxy resin motherboard printed circuit board. The semiconductor
plastic package was evaluated, and Table 5 shows the results.
Comparative Example 4
[0173] The same prepregs D and E as those in Comparative Example 3
were prepared. Two sheets of the prepreg E were used, and a
dual-side copper-clad laminate was prepared by laminate formation
at 170.degree. C. at 20 kgf/cm.sup.2 under a vacuum of 30 mmHg for
2 hours. Then, a printed circuit board was prepared in the same
manner as in Comparative Example 1, a portion on which a
semiconductor chip was to be mounted was bored, and a copper sheet
having a thickness of 200 .mu.m was bonded to the reverse surface
with a prepreg prepared by punching the above prepreg D under heat
and pressure, to obtain a heat-diffusing-sheet-attached printed
circuit board. The board caused distortion to some extent. A
semiconductor chip was directly bonded to the above heatdiffusing
sheet with a silver paste, followed by wire bonding connection and
encapsulation with a liquid epoxy resin. Solder balls were attached
to the surface opposite to the metal-attached surface. The
resultant semiconductor package was similarly connected to a
motherboard. The semiconductor plastic package was evaluated, and
Table 5 shows the results.
5 TABLE 5 Example 9 Example 10 CEx. 4 Heat Ord. state No failure No
failure No failure resistance 24 hours No failure No failure No
failure after moisture 48 hours No failure No failure No failure
absorption{circle over (2)} 72 hours No failure No failure No
failure 96 hours No failure No failure Partly peeled off 120 hours
No failure No failure Partly peeled off 144 hours No failure No
failure Partly peeled off 168 hours No failure No failure Partly
peeled off Heat Ord. state No failure No failure No failure
resistance 24 hours No failure No failure Partly after moisture
peeled off absorption{circle over (2)} 48 hours No failure No
failure Largely peeled off 72 hours No failure No failure Wire
broken 96 hours No failure No failure Wire broken 120 hours No
failure No failure Wire broken 144 hours No failure No failure --
168 hours No failure Partly -- peeled off Tg (.degree. C.) 234 235
145 Insulation Ord. state 5 .times. 10.sup.11 6 .times. 10.sup.11 6
.times. 10.sup.11 resistance 200 hours 5 .times. 10.sup.12 5
.times. 10.sup.12 2 .times. 10.sup.8 (.OMEGA.) after 500 hours 4
.times. 10.sup.11 7 .times. 10.sup.11 <10.sup.8 pressure 700
hours 6 .times. 10.sup.10 1 .times. 10.sup.10 -- cooker test 1000
hours 1 .times. 10.sup.10 8 .times. 10.sup.9 -- Migration Ord.
state 5 .times. 10.sup.13 6 .times. 10.sup.12 6 .times. 10.sup.12
resistance 200 hours 5 .times. 10.sup.11 5 .times. 10.sup.11 7
.times. 10.sup.8 (.OMEGA.) 500 hours 4 .times. 10.sup.11 3 .times.
10.sup.11 <10.sup.8 700 hours 1 .times. 10.sup.11 2 .times.
10.sup.11 -- 1000 hours 9 .times. 10.sup.10 8 .times. 10.sup.10 --
Heat (.degree. C.) 36 37 48 diffusibilty CEx. = Comparative Example
Ord. state = Ordinary state Tg = Glass transition temperature
Example 11
[0174] A varnish A was prepared in the same manner as in Example 1.
The varnish A was used to impregnate a 100 .mu.m thick glass woven
fabric and dried at 150.degree. C. to obtain a 150 .mu.m thick
semi-cured low-flow prepreg (prepreg B4) having a gelation time of
7 seconds at 170.degree. C. and a resin flow of 110 .mu.m at
170.degree. C. at 20 kgf/cmz for 5 minutes. Further, the same
impregnated glass woven fabric was dried at 145.degree. C. to
obtain a 107 .mu.m thick high-flow flow prepreg (prepreg C1) having
a gelation time of 120 seconds at 170.degree. C. and a resin flow
of 13 mm.
[0175] On the other hand, an alloy having a thickness of 200 .mu.m
and containing Cu: 97.3 %, Fe: 2.5% , P: 0.1% , Zn: 0.07% and Pb:
0.03% was provided for an inner layer metal sheet, and a protrusion
portion having a 13.times.13 mm square size and a height of 100
.mu.m formed by an etching method so as to be positioned in the
center of a package having 50.times.50 mm square size.
[0176] Then, black copper oxide treatment was carried out in the
same manner as in Example 1, and prepregs and electrolytic copper
foils were laminated, and the resultant set was laminate-formed
under the same conditions as those in Example 1 to integrate them,
whereby a dual-side copper-clad laminate was obtained.
[0177] A printed circuit board was completed in the same manner as
in Example 1 except that a through-hole was drilled in a clearance
hole portion.
[0178] A semiconductor chip having a 13.times.13 mm square size was
bonded and fixed to the protrusion portion with a silver paste,
then, wire bonding was carried out, the resultant set was
encapsulated with a silica-containing epoxy sealing compound by
transfer molding, and solder balls were attached, to obtain a
semiconductor package. The semiconductor package was connected to
an epoxy resin motherboard printed circuit board by melting the
solder balls . The semiconductor plastic package was evaluated, and
Table 6 shows the results.
Example 12
[0179] The same prepreg C1 in Example 1 was provided, a 12 .mu.m
thick electrolytic copper foil was placed on one surface of the
prepreg, a release film was placed on the other surface, and the
resultant set was laminate-formed at 200.degree. C. at 20
kgf/cm.sup.2 for 2 hours to prepare a single-side copper-clad
laminate.
[0180] A rolling copper sheet having a thickness of 300 .mu.m,
which was to constitute an inner layer, was processed in the same
manner as in Example 1 to form a protrusion having a 10.times.10 mm
square size and a height of 150 .mu.m. Further, a clearance hole
having a diameter of 0.6 mm was made. The same varnish A as that in
Example 1 was applied to the front and reverse surfaces by screen
printing such that no resin adhered to the metal protrusion
portion, and formed coatings were dried, to form resin layers on
the front and reverse surfaces. The resin layer on the reverse
surface being a high-flow resin layer having a thickness of 45
.mu.m and having a gelation time of 125 seconds at 170.degree. C.
and the resin layer on the front surface being a low-flow resin
layer having a thickness of 40 .mu.m and having a gelation time of
10 to 20 seconds at 170.degree. C.
[0181] A single-side copper-clad laminate which was prepared from
the above-obtained single-side copper-clad laminate by making a
hole greater than the protrusion portion by 40 .mu.m in a position
corresponding to the metal protrusion portion was placed on the
front surface of the above metal sheet, the same single-side
copper-clad laminate as that obtained above was placed on the
reverse surface, and the resultant set was laminate-formed under
the same conditions to prepare a dual-side copper-clad laminate. In
the clearance hole portion, a through-hole having a diameter of
0.20 mm was drilled in the center thereof so as not to be brought
into the metal sheet of the clearance hole portion. Through-holes
were similarly drilled in four corners so as to be in direct
contact with the metal sheet as heatdiffusible portions. After
desmear treatment, copper plating was carried out by electroless
plating and electric plating to form a 17 .mu.m thick copper
plating layer in the holes. A liquid etching resist was applied to
the front and reverse surfaces and dried to remove the solvents,
and then positive films were placed thereon, followed by exposure
and development to form front and reverse circuits. A plating
resist was formed on portions other than the laminate portion on
the protrusion portion, a bonding pad and a ball pad. The plating
was carried out with nickel and gold, to complete a printed circuit
board.
[0182] Then, a semiconductor chip was similarly bonded and followed
by encapsulation with a resin and attaching of solder balls, to
form a semiconductor plastic package. The semiconductor package was
similarly connected to an epoxy resin motherboard printed circuit
board. The semiconductor plastic package was evaluated, and Table 6
shows the results.
Example 13
[0183] A varnish A was prepared in the same manner as in Example 1.
A low-flow prepreg (prepreg B1) and the high-flow prepreg (prepreg
C1) were prepared in the same manner as in Example 11.
[0184] On the other hand, an alloy containing Cu: 97.45% , Fe: 2.4%
, P: 0.03% and Zn: 0.12% was provided for an inner layer metal
sheet, and a protrusion portion having a 13.times.13 mm square size
and a height of 220 .mu.m was formed by an etching method so as to
be positioned in the center of a-package having a 50.times.50 mm
square size.
[0185] Then, a clearance hole having a diameter of 0.6 mm was made
in the same manner as in Example 1.
[0186] The entire surface of the metal sheet was treated to form
black copper oxide, and the above prepreg B1 having a hole greater
than the protrusion portion by 110 .mu.m made by punching in a
position corresponding to the protrusion portion was used to cover
the upper surface thereof. The prepreg C was used to cover the
lower surface. Further, electrolytic copper foils having a
thickness of 12 .mu.m were placed on both of the prepregs. The
resultant set was laminate-formed to prepare a dual-side
copper-clad laminate, a circuit was formed on one surface of the
laminate, a slightly larger hole was made by punching in a portion
on which a semiconductor chip was to be mounted, black copper oxide
treatment was carried out, and the resultant laminate was placed on
the surface such that the surface on which the circuit was formed
faced downward. A copper foil having a thickness of 12 .mu.m was
placed on the prepreg on the reverse surface, and the resultant set
was laminate--formed/at 200.degree. C. at 20 kgf/cm.sup.2 at a
vacuum of 30 mmHg or less for 2 hours to integrate them, whereby a
double-side copper-clad laminate having the metal protrusion
portion exposed on the surface was obtained.
[0187] In the clearance hole portion, a through-hole was drilled
therein, and through-holes having a diameter of 0.2 mm were
similarly drilled in four corners so as to be in direct contact
with the metal sheet as heat-diffusible portions. After desmear
treatment, copper plating was carried out by electroless plating
and electric plating to form a 18 .mu.m thick copper plating layer
in the holes.
[0188] Front and reverse surface circuits were formed, and nickel
and gold plating, etc., were carried out, in the same manner as in
Example 1, to complete a printed circuit board. A semiconductor
chip having a 13.times.13 mm square size was bonded and fixed to
the protrusion portion with a silver paste, then, wire bonding was
carried out. The resultant set was encapsulated with a
silica-containing epoxy sealing compound by transfer molding, and
solder balls were attached, to obtain a semiconductor package. The
semiconductor package was connected to an epoxy resin motherboard
printed circuit board by melting the solder balls. The
semiconductor plastic package was evaluated, and Table 6 shows the
results.
6 TABLE 6 Example 11 Example 12 Example 13 Example 14 Heat Ordinary
No failure No failure No failure No failure resistance state after
72 hours No failure No failure No failure No failure moisture 96
hours No failure No failure No failure No failure absorption{circle
over (1)} 120 hours No failure No failure No failure No failure 144
hours No failure No failure No failure No failure 168 hours No
failure No failure No failure No failure Heat Ordinary No failure
No failure No failure No failure resistance state after 24 hours No
failure No failure No failure No failure moisture 48 hours No
failure No failure No failure No failure absorption{circle over
(2)} 72 hours No failure No failure No failure No failure 96 hours
No failure No failure No failure No failure 120 hours No failure No
failure No failure No failure 144 hours No failure No failure No
failure No failure 168 hours No failure No failure No failure No
failure Tg (.degree. C.) 233 235 234 234 Insulation Ordinary 5
.times. 10.sup.11 6 .times. 10.sup.11 6 .times. 10.sup.11 4 .times.
10.sup.11 resistance state (.OMEGA.) after 200 hours 6 .times.
10.sup.12 6 .times. 10.sup.12 6 .times. 10.sup.12 6 .times.
10.sup.12 pressure 500 hours 3 .times. 10.sup.11 5 .times.
10.sup.11 5 .times. 10.sup.11 5 .times. 10.sup.11 cooker 700 hours
7 .times. 10.sup.10 1 .times. 10.sup.10 6 .times. 10.sup.10 8
.times. 10.sup.10 test 1000 hours 1 .times. 10.sup.10 9 .times.
10.sup.9 2 .times. 10.sup.10 6 .times. 10.sup.10 Migration Ordinary
7 .times. 10.sup.13 8 .times. 10.sup.12 6 .times. 10.sup.13 5
.times. 10.sup.13 resistance state (.OMEGA.) 200 hours 5 .times.
10.sup.11 4 .times. 10.sup.11 4 .times. 10.sup.11 6 .times.
10.sup.11 500 hours 4 .times. 10.sup.11 3 .times. 10.sup.11 3
.times. 10.sup.11 5 .times. 10.sup.11 700 hours 2 .times. 10.sup.11
2 .times. 10.sup.11 2 .times. 10.sup.11 9 .times. 10.sup.10 1000
hours 9 .times. 10.sup.10 8 .times. 10.sup.10 9 .times. 10.sup.10 6
.times. 10.sup.10 Heat diffusibility (.degree. C.) 36 36 36 37 Tg =
Glass transition temperature
Example 14
[0189] A varnish A was prepared in the same manner as in Example 1.
The varnish A was used to impregnate a 100 .mu.m thick glass woven
fabric and dried at 150.degree. C. to obtain a 107 .mu.m thick
semi-cured low-flow prepreg (prepreg B5) having a gelation time of
7 seconds at 170.degree. C. and a resin flow of 110 .mu.m at
170.degree. C. at 20 kgf/cm.sup.2 for 5 minutes. Further,the same
impregnated glass woven fabric was dried to obtain a 109 .mu.m
thick high-flow prepreg C2 having a gelation time of 114 seconds
and a resin flow of 13 mm.
[0190] On the other hand, a copper sheet having a thickness of 200
.mu.m, which was to constitute an inner layer, was provided, and a
liquid etching resist was applied to the entire surface thereof to
form a coating having a thickness of 20 .mu.m. The coating was
dried, and then the coated copper sheet was irradiated with
ultraviolet light such that etching resist for a protrusion portion
was left on the front surface and that etching resist for a
clearance hole portion was removed on the reverse surface, followed
by development with a 1% sodium carbonate aqueous solution. Then,
etching was carried out concurrently on both surfaces at 1.0
kgf/cm.sup.2 on the front surface and at 2.5 kgf/cm.sup.2 on the
reverse surface to form a protrusion having a 13.times.13 mm square
size and a height of 100 .mu.m so as to be positioned in the center
of a package having a 50.times.50 mm square size and a clearance
hole having a diameter of 0.6 mm. The clearance hole had almost the
same diameters on the upper and lower surfaces.
[0191] After black copper oxide treatment of the metal sheet, the
prepregs were placed, 12 .mu.m thick electrolytic copper foils were
also placed and laminate-formation for integration was carried out,
in the same manner as in Example 1.
[0192] A through-hole was made in the laminate of the metal sheet
in the same manner as in Example 1, and a 17 .mu.m thick copper
plating layer was formed in the hole in the same manner as in
Example 1.
[0193] Front and reverse surface circuits were formed, and plating
with nickel and gold were carried out, in the same manner as in
Example 1, to complete a printed circuit board. A semiconductor
chip having a 13.times.13 mm square size was bonded to the surface
protrusion portion, and wire bonding and encapsulation with a resin
were carried out, in the same manner as in Example 1, to prepare a
semiconductor package. The semiconductor plastic package was
evaluated, and Table 7 shows the results.
Comparative Example 5
[0194] The same inner layer metal sheet as that in Example 14 was
etched on both the surfaces at a pressure of 2 kgf/cm.sup.2. The
resultant metal sheet had a clearance hole whose diameter on the
front surface was 0.3 mm and whose diameter on the reverse surface
was 0.6 mm, and the clearance hole was thus formed non-uniformly.
When a hole having a diameter of 0.25 mm was made, 67% by number of
the through-hole was in contact with the inner layer metal
sheet.
Example 15
[0195] A varnish A was prepared in the same manner as in Example 1.
The varnish A was used to impregnate a 100 .mu.m thick glass woven
fabric and dried at 150.degree. C. to obtain a 105 82 m thick
semi-cured low-flow prepreg (prepreg B2) having a gelation time of
7 seconds at 170.degree. C. and a resin flow of 110 .mu.m at
170.degree. C. at 20 kgf/cm.sup.2 for 5 minutes. Further, the same
impregnated glass woven fabric was dried to obtain a 109 .mu.m
thick high-flow prepreg C2 having a gelation time of 114 seconds
and a resin flow of 13 mm.
[0196] On the other hand, a copper sheet having a thickness of 250
.mu.m, which was to constitute an inner layer, was provided, and a
liquid etching resist was applied to the entire surface thereof to
form a coating having a thickness of 20 .mu.m. The coating was
dried to remove the solvents, and a negative film for leaving a
clearance hole portion was placed and then irradiated with
ultraviolet light. Resist film on the clearance hole portion was
removed with a 1% sodium carbonate aqueous solution. Then, etching
was carried out on both surfaces to make a clearance hole having a
diameter of 0.6 mm. Then, embossing was carried out under pressure
applied to the lower surface, to form a protrusion having a
13.times.mm square size and a height of 100 .mu.m so as to be
positioned in the center of a package having a 50.times.50 mm
square size. The copper sheet had a structure in which the lower
surface was dented.
[0197] Black copper oxide treatment of the metal sheet was carried
out, the prepregs were placed, 8 .mu.m thick electrolytic copper
foils were also placed and laminate-formation for integration was
carried out, in the same manner as in Example 1. A through-hole was
made in the clearance hole portion in the same manner as in Example
1 except that the through-hole was drilled, and a 17 .mu.m thick
copper plating layer was formed in the hole.
[0198] Front and reverse surface circuits were formed, and plating
with nickel and gold were carried out, in the same manner as in
Example 1, to complete a printed circuit board. A semiconductor
chip having a 13.times.13 mm square size was bonded to the surface
protrusion portion, and wire bonding and encapsulation with a resin
were carried out, in the same manner as in Example 1, to prepare a
semiconductor package. Further, solder balls were attached, and the
semiconductor package was bonded onto an epoxy resin motherboard
printed circuit board by heating and melting the solder balls. The
semiconductor plastic package was evaluated, and Table 7 shows the
results.
[0199] Example 16
[0200] An alloy having a thickness of 250 .mu.m and containing Cu:
99.86 wt %, Fe: 0.11 wt % and P: 0.03 wt %, which was to constitute
an inner layer, was provided and processed in the same manner as in
Example 1, to make a clearance hole, and four protrusions having a
4.times.4 mm square size and a height of 100 .mu.m each were formed
on the surface. The reverse surface was dented. Further, a
clearance hole having a diameter of 0.6 mm was made in the same
manner as in Example 1. Prepregs were placed on the metal sheet,
and 12 .mu.m thick electrolytic copper foils were placed on both
sides, in the same manner as in Example 1, and the resultant set
was laminate-formed under the same conditions as those in Example
1. A through-hole having a diameter of 0.20 mm was drilled in the
center so as not to be in contact with the metal of the clearance
hole portion. For heat-diffusible portions, through-holes having
the same diameters were drilled so as to be in contact with the
metal sheet. After desmear treatment, copper plating was carried
out by electroless plating and electric plating to form a 17 .mu.m
thick copper plating layer in the holes. Front and reverse surface
circuits were formed, and plating with nickel and gold were carried
out, in the same manner as in Example 1, to complete a printed
circuit board. Semiconductor chips were bonded thereto, and wire
bonding and encapsulation with a resin were carried out, in the
same manner as in Example 1, to form a semiconductor package. The
semiconductor package was similarly bonded to a motherboard. The
semiconductor plastic package was evaluated, and Table 7 shows the
results.
7 TABLE 7 Example 15 Example 16 Heat Ord. state No failure No
failure resistance 24 hours No failure No failure after moisture 48
hours No failure No failure absorption{circle over (1)} 72 hours No
failure No failure 96 hours No failure No failure 120 hours No
failure No failure 144 hours No failure No failure 168 hours No
failure No failure Heat Ord. state No failure No failure resistance
24 hours No failure No failure after 48 hours No failure No failure
moisture 72 hours No failure No failure absorption{circle over (2)}
96 hours No failure No failure 120 hours No failure No failure 144
hours No failure No failure 168 hours No failure No failure Tg
(.degree. C.) 235 234 Insulation Ord. state 5 .times. 10.sup.11 6
.times. 10.sup.11 resistance 200 hours 5 .times. 10.sup.12 7
.times. 10.sup.12 (.OMEGA.) after 500 hours 3 .times. 10.sup.11 2
.times. 10.sup.11 pressure 700 hours 3 .times. 10.sup.10 5 .times.
10.sup.10 cooker test 1000 hours 2 .times. 10.sup.10 1 .times.
10.sup.10 Migration Ord. state 4 .times. 10.sup.13 5 .times.
10.sup.12 resistance 200 hours 4 .times. 10.sup.11 5 .times.
10.sup.11 (.OMEGA.) 500 hours 6 .times. 10.sup.11 3 .times.
10.sup.11 700 hours 9 .times. 10.sup.10 1 .times. 10.sup.11 1000
hours 8 .times. 10.sup.10 8 .times. 10.sup.10 Heat (.degree. C.) 36
37 diffusibilty Ord. state = Ordinary state Tg = Glass transition
temperature
Example 17
[0201] A varnish A was prepared in the same manner as in Example
1.
[0202] The varnish A was used to impregnate a 100 .mu.m thick glass
woven fabric, and the impregnated fabric was dried at 150.degree.
C. to obtain a 105 .mu.m thick semicured prepreg (prepreg B6)
having a gelation time of 10 seconds at 170.degree. C. and a resin
flow of 85 .mu.m at 170.degree. C. at 20 kgf/cm.sup.2 for 5
minutes.
[0203] A 250 .mu.m thick copper sheet which was to constitute an
inner layer metal sheet was provided. A protrusion having a
13.times.13 mm square size and a height of 100 .mu.m was formed on
one surface of the copper sheet, and a protrusion having a
13.times.13 mm square size and a height of 100 .mu.m was formed on
the other surface of the copper sheet, by an etching method so as
to be positioned in the center of a package having a 50.times.50 mm
square size.
[0204] Then, a liquid etching resist was applied to the entire
surface to form a coating having a thickness of 25 .mu.m, and the
coating was dried to remove the solvents. Negative films having
holes for the protrusion portions were placed on both sides, and
portions other than a clearance hole portion were exposed to
ultraviolet light, and the resist film on the clearance hole
portion was removed with a 1% sodium carbonate aqueous solution.
Then, a clearance hole having a diameter of 0.6 mm was made by
etching on both sides.
[0205] The entire surface of the metal sheet was treated to form
black copper oxide, sheets of the above prepreg B having a hole
greater than the protrusion portion by 50 .mu.m made in portions
corresponding to the protrusion portions with a router were covered
on both the surfaces, 18 .mu.m thick electrolytic copper foils were
placed on both sides, and the resultant set was laminate-formed at
200.degree. C. at 20 kgf/cm.sup.2 under a vacuum of 30 mmHg or less
for 2 hours to integrate them.
[0206] In the clearance hole portion, a through-hole having a
diameter of 0.25 mm was made in the center with a laser so as not
to be in contact with the metal of the clearance hole portion.
After desmear treatment, copper plating was carried out by
electroless plating and electric plating to form a 17 .mu.m thick
copper plating layer in the hole.
[0207] A liquid etching resist was applied to the front and reverse
surfaces and dried, and positive films were placed, followed by
exposure and development to form front and reverse surface
circuits. Copper foil on the protrusion portions was also
simultaneously removed by etching.
[0208] A plating resist was formed on portions other than the
protrusion portions, a bonding pad and a ball pad, and plating was
carried out with nickel and gold, to complete a printed circuit
board.
[0209] Then, a semiconductor chip having a 13.times.13 mm square
size was bonded and fixed to the upper surface protrusion with a
silver paste, wire bonding was carried out, then, the resultant set
was encapsulated with a silica-containing epoxy sealing compound by
transfer molding, and solder balls were attached to a ball pad, to
obtain a semiconductor package (FIG. 7). The semiconductor package
was connected to an epoxy resin motherboard printed circuit board
by melting the solder balls. The semiconductor plastic package was
evaluated, and Table 8 shows the results.
Example 18
[0210] One sheet of the same prepreg B6 as that obtained in Example
17 was used, a 18 .mu.m thick electrolytic copper foil was placed
on one surface, a release film was placed on the other surface, and
the resultant set was laminate-formed at 200.degree. C. at 20
kgf/cm.sup.2 for 2 hours to prepare a single-side copper-clad
laminate. A 250 .mu.m thick alloy sheet containing Cu: 99.86 wt %,
Fe: 0.11 wt % and P: 0.03 wt %, which was to constitute an inner
layer, was provided and processed in the same manner as in Example
17, to form protrusions having the same size and the same height as
those in Example 17. Further, a clearance hole having a diameter of
0.6 mm was made, and prepregs B6 were similarly placed on both
upper and lower sides. The above-obtained single-side copper-clad
laminate sheets were placed on both sides, and the resultant set
was laminate-formed under the same conditions. In the clearance
hole portion, a through-hole having a diameter of 0.20 mm was
drilled in the center so as not to be in contact with the metal of
the clearance hole portion. After desmear treatment, copper plating
was carried out by electroless plating and electric plating to form
a 17 .mu.m thick copper plating layer in the hole.
[0211] A liquid etching resist was applied to the front and reverse
surfaces and dried to remove the solvents, and positive films were
placed, followed by exposure and development to form front and
reverse surface circuits.
[0212] A plating resist was formed on portions other than laminate
sheet portions on the protrusion portions, a bonding pad and a ball
pad. Plating was carried out with nickel and gold, and substrate of
the laminate sheet portions on the central copper alloy sheet
protrusion portions was removed by cutting with a router, to
complete a printed circuit board. Then, a semiconductor chip was
similarly bonded and fixed, followed by encapsulation with a resin
and attaching of solder balls, to obtain a semiconductor plastic
package. The semiconductor package was connected to a motherboard
printed circuit board in the same manner as in Example 17. The
semiconductor plastic package was evaluated, and Table 8 shows the
results.
8 TABLE 8 Example 17 Example 18 Heat Ordinary state No failure No
failure resistance 120 hours No failure No failure after moisture
144 hours No failure No failure Absorption {circle over (1)} 168
hours No failure No failure Heat Ordinary state No failure No
failure resistance 24 hours No failure No failure after moisture 48
hours No failure No failure absorption {circle over (2)} 72 hours
No failure No failure 96 hours No failure No failure 120 hours No
failure No failure 144 hours No failure No failure 168 hours No
failure Partly peeled Tg (.degree. C.) 235 -- Insulation Ord. state
4 .times. 10.sup.11 -- resistance 200 hours 4 .times. 10.sup.12
(.OMEGA.) after 500 hours 5 .times. 10.sup.11 pressure 700 hours 8
.times. 10.sup.10 cooker test 1000 hours 2 .times. 10.sup.10
Migration Ord. state 5 .times. 10.sup.13 resistance 200 hours 5
.times. 10.sup.11 (.OMEGA.) 500 hours 3 .times. 10.sup.11 700 hours
1 .times. 10.sup.11 1000 hours 8 .times. 10.sup.10 Heat (.degree.
C.) 32 35 diffusibilty Tg = Glass transition temperature
Example 19
[0213] A varnish A was prepared in the same manner as in Example 1.
The varnish A was used to impregnate a 100 .mu.m thick glass woven
fabric, and the impregnated fabric was dried at 150.degree. C. to
obtain a 105 .mu.m thick semi-cured prepreg (prepreg B2) having a
gelation time of 7 seconds at 170.degree. C. and a resin flow of
110 .mu.m at 170.degree. C. at 20 kgf/cm.sup.2 for 5 minutes.
Further, there was also prepared a 109 .mu.m thick prepreg C2
having a gelation time of 114 seconds and a resin flow of 13
mm.
[0214] A 250 .mu.m thick copper sheet which was to constitute an
inner layer metal sheet was provided. A protrusion having a
13.times.13 mm square size and a height of 100 .mu.m was formed on
one surface so as to be positioned in the center of a package
having a 50.times.50 m square size, and protrusions having a width
of 5 mm and a height of 100 .mu.m were formed in marginal portions
on the front and reverse surfaces. A clearance hole having a
diameter of 0.6 mm was made in the same manner as in Example 19
except that the thickness of an etching resist was changed to 20
.mu.m. The entire surface of the metal sheet was treated to form
black copper oxide, and the above low-flow prepreg B having holes
greater than the protrusion portions by 50 .mu.m made in portions
corresponding to the protrusion portions with a router was covered
on the front surface. The high-flow prepreg C having a hole greater
than a heat-diffusing protrusion portion by 100 .mu.m was covered
on the reverse surface, and 18 .mu.m thick electrolytic copper
foils were placed on both sides. The resultant set was
laminate-formed at 200.degree. C. at 20 kgf/cm.sup.2 under a vacuum
of 30 mmHg or less for 2 hours to integrate them.
[0215] In the clearance hole portion, a through-hole having a
diameter of 0.25 mm was drilled in the center so as not to be in
contact with the metal of the clearance hole portion. After desmear
treatment, copper plating was carried out by electroless plating
and electric plating to form a 17 .mu.m thick copper plating layer
in the hole. A liquid etching resist was applied to the front and
reverse surfaces and dried, and positive films were placed,
followed by exposure and development to form front and reverse
surface circuits. Copper foil on the protrusion portions was also
simultaneously removed by etching, to create a printed circuit
board. A plating resist was formed on portions other than the
protrusion portions, a bonding pad and a ball pad, and plating was
carried out with nickel and gold, to complete the printed circuit
board.
[0216] Then, a semiconductor chip having a 13.times.13 mm square
size was bonded and fixed to the upper surface protrusion with a
silver paste, wire bonding was carried out, then, the resultant set
was encapsulated with a silica-containing epoxy sealing compound by
transfer molding, and solder balls were attached, to obtain a
semiconductor package (FIG. 9). The semiconductor package was
connected to a motherboard printed circuit board by melting the
solder balls under heat. The semiconductor plastic package was
evaluated, and Table 9 shows the results.
Example 20
[0217] One sheet of the same prepreg B2 as that obtained in Example
19 was used. A 18 .mu.m thick electrolytic copper foil was placed
on one surface, a release film was placed on the other surface, and
the resultant set was laminate-formed at 200.degree. C. at 20
kgf/cm.sup.2 for 2 hours to prepare a single-side copper-clad
laminate.
[0218] A 250 .mu.m thick alloy sheet containing Cu: 99.86 wt %, Fe:
0.11 wt % and P: 0.03 wt %, to constitute an inner layer, was
provided and processed in the same manner as in Example 19, to form
two protrusions having the same size and the same height as those
in Example 19 and protrusions having a width of 5 mm and a height
of 100 .mu.m in marginal portions on the front and reverse
surfaces. Further, a clearance hole having a diameter of 0.6 mm was
made, and the prepreg B having holes for the protrusion portions
was placed on the upper surface, and the prepreg C having a hole in
a position corresponding to a heath diffusing protrusion portion
was placed on the reverse surface. The above-obtained single-side
copper-clad laminate sheets were placed on both sides, and the
resultant set was laminate-formed under the same conditions. In the
clearance hole portion, a through-hole having a diameter of 0.20 mm
was drilled in the center so as not to be in contact with the metal
of the clearance hole portion. After desmear treatment, copper
plating was carried out by electroless plating and electric plating
to form a 17 .mu.m thick copper plating layer in the hole. A liquid
etching resist was applied to the front and reverse surfaces and
dried to remove the solvents, and positive films were placed,
followed by exposure and development to form front and reverse
surface circuits. A plating resist was formed on portions other
than bonding pad and ball pad portions. Plating was carried out
with nickel and gold, and substrate of the laminate sheet portions
on the central copper alloy sheet protrusion portions was removed
by cutting with a router, to complete a printed circuit board.
[0219] Then, a semiconductor chip was similarly bonded and fixed,
followed by encapsulation with a resin and attaching of solder
balls, to obtain a semiconductor plastic package. The semiconductor
package was connected to a motherboard printed circuit board in the
same manner as in Example 19. The semiconductorplastic package was
evaluated, and Table 9 shows the results.
9 TABLE 9 Example 19 Example 20 Heat Ordinary state No failure No
failure resistance 24 hours No failure No failure after moisture 48
hours No failure No failure Absorption {circle over (1)} 72 hours
No failure No failure 96 hours No failure No failure 120 hours No
failure No failure 144 hours No failure No failure 168 hours No
failure No failure Heat Ordinary state No failure No failure
resistance 24 hours No failure No failure after moisture 48 hours
No failure No failure Absorption {circle over (2)} 72 hours No
failure No failure 96 hours No failure No failure 120 hours No
failure No failure 144 hours No failure No failure 168 hours No
failure No failure Tg (.degree. C.) 234 -- Insulation Ordinary
state 3 .times. 10.sup.11 -- resistance 200 hours 5 .times.
10.sup.12 (.OMEGA.) after 500 hours 5 .times. 10.sup.11 pressure
700 hours 8 .times. 10.sup.10 cooker test 1000 hours 4 .times.
10.sup.10 Migration Ord. state 5 .times. 10.sup.13 -- resistance
200 hours 4 .times. 10.sup.11 (.OMEGA.) 500 hours 5 .times.
10.sup.11 700 hours 9 .times. 10.sup.10 1000 hours 8 .times.
10.sup.10 Heat (.degree. C.) 30 31 diffusibilty Temperature 100
cycles No failure No failure cycle test 300 cycles No failure No
failure 500 cycles No failure Partly peeled off Tg = Glass
transition temperature
Example 21
[0220] A varnish A was prepared in the same manner as in Example 1.
The varnish A was used to impregnate a 100 .mu.m thick glass woven
fabric, and the impregnated fabric was dried at 150.degree. C. to
obtain a 105 .mu.m thick semi cured prepreg (prepreg B2) having a
gelation time of 7 seconds at 170.degree. C. and a resin flow of
110 dun at 170.degree. C. at 20 kgf/cm.sup.2 for 5 miutes. Further,
there was also prepared a 109 .mu.m thick prepreg C2 having a
gelation time of 114 seconds and a resin flow of 13 mm.
[0221] A 250.mu.m thick coppersheetwhichwas to constitute an inner
layermetal sheet was provided. A protrusion having a 13.times.13 mm
square size and a height of 100 .mu.m was formed on one surface of
the copper sheet so as to be positioned in the center of a package
having a 50.times.50 mm square size, and a protrusion having a
width of 5 mm and a height of 100 .mu.m was formed in a marginal
portion on the lower surface. Then, a semiconductor package was
prepared in the same manner as in Example 19. Solder balls were
attached to a ball pad of the package, and the semiconductor
package was connected to an epoxy resin motherboard printed circuit
board by melting the solder balls under heat. The semiconductor
plastic package was evaluated, and Table 10 shows the results.
Example 22
[0222] One sheet of the same prepreg B2 as that obtained in Example
21 was used. A 18 .mu.m thick electrolytic copper foil was placed
on one surface, a release film was placed on the other surface, and
the resultant set was laminate formed at 200.degree. C. at 20
kgf/cm.sup.2 for 2 hours to prepare a single-side copper-clad
laminate.
[0223] A 250 .mu.m thick alloy sheet containing Cu: 99.86 wt %, Fe:
0.11 wt % and P: 0.03 wt %, to constitute an inner layer, was
provided and processed in the same manner as in Example 21, to form
two protrusions having the same size and the same height as those
in Example 19 and a protrusion having a width of 5 mm and a height
of 100 .mu.m in a marginal portion on the lower surface.
[0224] A clearance hole was made, a through-hole was made, plating
with copper in the through-hole, and front and reverse surface
circuits were formed, in the same manner as in Example 20.
[0225] A plating resist was formed on portions other than the
substrate portion on which a semiconductor chip was to be mounted,
a bonding pad portion, a ball pad portion and a
heat-diffusing-metal exposed portion on the lower (reverse)
surface. Plating was carried out with nickel and gold, and
substrate of the laminate sheet portion on the copper sheet
protrusion portion was removed by cutting with a router, to
complete a printed circuit board. Then, a semiconductor chip was
bonded, wire bonding was carried out, and the resultant set was
encapsulated with a resin to form a semiconductor package. The
semiconductor package was connected to a motherboard printed
circuit board with solder balls in the same manner as in Example
21. The semiconductor plastic package was evaluated, and Table 10
shows the results.
10 TABLE 10 Example 21 Example 22 Heat Ordinary state No failure No
failure resistance 24 hours No failure No failure after moisture 48
hours No failure No failure Absorption {circle over (1)} 72 hours
No failure No failure 96 hours No failure No failure 120 hours No
failure No failure 144 hours No failure No failure 168 hours No
failure No failure Heat Ordinary state No failure No failure
resistance {circle over (2)} 24 hours No failure No failure after
moisture 48 hours No failure No failure Absorption {circle over
(1)} 72 hours No failure No failure 96 hours No failure No failure
120 hours No failure No failure 144 hours No failure partly peeled
off 168 hours partly peeled partly peeled off off Tg (.degree. C.)
234 -- Insulation Ordinary state 3 .times. 10.sup.11 -- resistance
200 hours 5 .times. 10.sup.12 (.OMEGA.) after 500 hours 5 .times.
10.sup.11 pressure 700 hours 8 .times. 10.sup.10 cooker 1000 hours
4 .times. 10.sup.10 treatment Migration Ord. state 5 .times.
10.sup.13 -- resistance 200 hours 4 .times. 10.sup.11 (.OMEGA.) 500
hours 5 .times. 10.sup.11 700 hours 9 .times. 10.sup.10 1000 hours
8 .times. 10.sup.10 Heat (.degree. C.) 30 31 diffusibilty
Temperature 100 cycles No failure No failure cycle test 300 cycles
No failure No failure 500 cycles No failure Partly peeled off Tg =
Glass transition temperature
Example 23
[0226] A varnish A was prepared in the same manner as in Example 1.
The varnish A was used to impregnate a 100 .mu.m thick glass woven
fabric, and the impregnated fabric was dried to obtain a 140 .mu.m
thick semi-cured prepreg (prepreg B7) having a gelation time of 50
seconds at 170.degree. C. and a resin flow of 10 mm at 170.degree.
C. at 20 kgf/cm.sup.2 for 5 minutes. Further, here was also
prepared a 126 .mu.m thick prepreg C3 having a gelation time of 7
seconds and a resin flow of 95 .mu.m.
[0227] A 100 .mu.m thick alloy sheet containing Cu: 99.9 wt %, Fe:
0.07 wt % and P: 0.03 wt %, to constitute an inner layer, was
provided. A liquid etching resist was applied to the upper and
lower surfaces of the alloy sheet to form a coating having a
thickness of 25 .mu.m, and the coating was dried. Then, on the
front surface, an etching resist having a 13.times.13 mm square
size was left so as to be positioned in the center of a package
having a 50.times.50 mm square size, and on the reverse surface,
etching resist was left on its entire surface other than a
clearance hole portion. A clearance hole having a 13.times.13 mm
square size and a height of 120 .mu.m was formed in the center of
the surface by etching both sides. The entire surface of the metal
sheet was treated to form black copper oxide. The prepreg C3 having
a hole slightly greater than the metal protrusion portion made by
punching was placed on the front surface, the above prepreg B7 was
placed on the reverse surface, 12 .mu.m thick electrolytic copper
foils were placed on outsides thereof, and the resultant set was
laminate formed at 200.degree. C. at 20 kgf/cm.sup.2 for 2 hours to
fill the resin in the clearance hole portion and to integrate
them.
[0228] In the through-hole portion, a through-hole having a
diameter of 0.25 mm was drilled in the center so as not to be in
contact with the metal core, and further, 625 holes having a
diameter of 120 .mu.m were made in the reverse surface with a
carbon dioxide gas laser such that the holes reached the metal
core. Plasma surface treatment and desmear treatment were carried
out, and then, copper plating was carried out, and the through-hole
portion was plated with copper. Further, all the via holes on the
reverse surface were also plated with copper to be filled. Then,
circuits were formed on the front and reverse surfaces, and a
plating resist was covered on portions other than the
semiconductor-chip-mounting portion and a bonding pad portion on
the surface and a ball pad portion on the reverse surface, and
those portions were plated with nickel and gold, to obtain a
printed circuit board.
[0229] A semiconductor chip having a 13.times.13 mm square size was
bonded and fixed to the metal protrusion portion on the front
surface with a silver paste, wire bonding was carried out, then,
the semiconductor chip, the wire portion and the bonding pad
portion were encapsulated with a silica-containing epoxy sealing
compound by transfer molding, and solder balls were attached to the
solder ball pad on the reverse surface, to obtain a semiconductor
package (FIG. 10). The semiconductor package was connected to an
epoxy resin motherboard printed circuit board by melting the solder
balls. The semiconductor plastic package was evaluated, and Table
11 shows the results.
11 TABLE 11 Example 23 Heat resistance Ordinary state No failure
after moisture 24 hours No failure Absorption {circle over (1)} 48
hours No failure 72 hours No failure 96 hours No failure 120 hours
No failure 144 hours No failure 168 hours No failure Heat
resistance {circle over (2)} Ordinary state No failure after
moisture 24 hours No failure Absorotion {circle over (1)} 48 hours
No failure 72 hours No failure 96 hours No failure 120 hours No
failure 144 hours No failure 168 hours partly peeled Tg (.degree.
C.) 234 Heat diffusibilty (.degree. C.) 32 Tg: Glass transition
temperature
* * * * *