U.S. patent application number 10/168403 was filed with the patent office on 2003-07-17 for multilayer printed wiring board and method of manufacturing the same.
Invention is credited to Ohsawa, Shinji, Okamoto, Hiroaki, Saijo, Kinji, Yoshida, Kazuo.
Application Number | 20030133277 10/168403 |
Document ID | / |
Family ID | 18480606 |
Filed Date | 2003-07-17 |
United States Patent
Application |
20030133277 |
Kind Code |
A1 |
Saijo, Kinji ; et
al. |
July 17, 2003 |
Multilayer printed wiring board and method of manufacturing the
same
Abstract
A structure of a multilayer printed wiring board having a wiring
lead-out port can be easily formed. A large number of products can
be easily manufactured with good size reproducibility. A method of
manufacturing the same is also are disclosed. The multilayer
printed wiring board is characterized by having a signal circuit
conductor perfectly covered by an earth circuit in its inside and a
wiring lead-out port. A signal circuit conductor having a branch
pattern is preferable. The multilayer printed wiring board is
manufactured by selectively etching the copper of a cladding sheet
manufactured by bonding a copper foil to a nickel foil with 0.1-3%
reduction and forming a signal circuit conductor perfectly covered
by an earth circuit and the wiring lead-out port.
Inventors: |
Saijo, Kinji;
(Yamaguchi-ken, JP) ; Yoshida, Kazuo;
(Yamaguchi-ken, JP) ; Okamoto, Hiroaki;
(Yamaguchi-ken, JP) ; Ohsawa, Shinji;
(Yamaguchi-ken, JP) |
Correspondence
Address: |
BROWDY AND NEIMARK, P.L.L.C.
624 NINTH STREET, NW
SUITE 300
WASHINGTON
DC
20001-5303
US
|
Family ID: |
18480606 |
Appl. No.: |
10/168403 |
Filed: |
November 27, 2002 |
PCT Filed: |
December 21, 2000 |
PCT NO: |
PCT/JP00/09070 |
Current U.S.
Class: |
361/774 |
Current CPC
Class: |
Y10T 29/49126 20150115;
Y10T 29/49155 20150115; Y10T 29/4913 20150115; H05K 2203/0384
20130101; H05K 2203/0733 20130101; Y10T 29/49151 20150115; H05K
1/0221 20130101; H05K 3/062 20130101; H05K 2201/0361 20130101; H05K
2201/09254 20130101; Y10T 29/49156 20150115; H05K 3/4647
20130101 |
Class at
Publication: |
361/774 |
International
Class: |
H01R 009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 22, 1999 |
JP |
11/363952 |
Claims
1. A multilayer printed wiring board characterized in including a
signal circuit conductor completely covered by an earth circuit at
an inner portion thereof as well as providing a wiring lead-out
port.
2. The multilayer printed wiring board according to claim 1,
wherein the signal circuit conductor includes a branch pattern.
3. A method of manufacturing a multilayer printed wiring board,
characterized in forming a signal circuit conductor completely
covered by an earth circuit and a wiring lead-out port at an inner
portion thereof by selective etching of copper with regard to a
cladding sheet for the multilayer printed wiring board manufactured
by bringing a copper foil material and a nickel foil material into
press contact with each other by a reduction of 0.1 to 3%.
4. The method of manufacturing a multilayer printed wiring board
according to claim 3, wherein the cladding sheet for the multilayer
printed wiring board comprises five layers of
copper/nickel/copper/nickel/copper.
5. The method of manufacturing a multilayer printed wiring board
according to claim 3 or 4, wherein the cladding sheet for the
multiplayer printed wiring board is manufactured by bringing the
copper foil material provided with nickel plating at one face or
two faces thereof and other copper foil material or a copper foil
material provided with nickel plating at one face thereof into
press contact with each other by the reduction of 0.1 to 3%.
6. A method of manufacturing a multilayer printed wiring board,
characterized in forming a signal circuit conductor completely
covered by an earth circuit at an inner portion thereof by
selective etching of copper with regard to a cladding sheet for the
multilayer printed wiring board manufactured by bringing a copper
foil material and a silver foil material into press contact with
each other by a reduction of 0.1 to 3%.
7. The method of manufacturing a multiplayer printed wiring board
according to claim 6, wherein the cladding sheet for the multilayer
printed wiring board comprises three layers of
copper/silver/copper.
8. The method of manufacturing a multilayer printed wiring board
according to claim 6 or 7, wherein the cladding sheet for the
multilayer printed wiring board is manufactured by bringing a
copper foil material provided with silver plating at one face
thereof and other copper foil material into press contact with each
other by a reduction of 0.1 to 3%.
9. The method of manufacturing a multilayer printed wiring board
according to any one of claims 3 to 5, characterized in forming a
resist pattern for forming a circuit shield wall and for forming
the wiring lead-out port at the copper layer on the one face of the
cladding sheet for the multilayer printed wiring board according to
any one of claims 3 to 5, thereafter carrying out selective etching
of copper to thereby form the circuit shield wall and the wiring
lead-out port, removing the nickel layer, successively coating an
insulating resin on an etching face, thereafter forming a resist
pattern for forming a circuit shield wall at a copper layer on a
rear face of the cladding sheet, thereafter carrying out selective
etching of copper to thereby form the circuit shield wall, etching
the intermediate copper layer to thereby form a signal circuit,
coating an insulating resin on an etching face and plating copper
on two faces thereof to thereby form the shield wall.
10. The method of manufacturing a multilayer printed wiring board
according to claims 6 to 8, characterized in forming a resist
pattern for forming a circuit shield wall or for forming a wiring
lead-out port at the copper layer on one face of the cladding sheet
with regard to the cladding sheet for a multilayer printed wiring
board according to any one of claims 6 to 8, thereafter carrying
out selective etching of copper to thereby form the circuit shield
wall, successively coating an insulating resin on an etching face,
thereafter forming a resist pattern for forming a circuit shield
wall at the copper layer on a rear face of the cladding sheet,
thereafter carrying out selective etching of copper to thereby form
the circuit shield wall, forming a signal circuit by etching the
intermediary copper layer, coating an insulating resin on an
etching face and thereafer plating copper at two faces other than a
portion for constituting a wiring lead-out port to thereby form the
shield wall.
11. The method of manufacturing a multilayer printed wiring board
according to claim 9 or 10, wherein the signal circuit conductor is
constituted by a shape including a branch pattern.
12. A method of forming a wiring lead-out port at a multilayer
printed wiring board, characterized in forming a resist pattern for
forming the wiring lead-out port at a copper layer on one face of a
cladding sheet for a multilayer printed wiring board according to
any one of claim 3 to 5, thereafter carrying out selective etching
of copper to thereby form a shield wall of the wiring lead-out
port, removing a nickel layer, successively coating an insulating
resin on an etching face, thereafter etching a copper layer on a
rear face of the cladding sheet and coating an insulating resin on
an etching face.
13. A method of forming a wiring lead-out port on the multilayer
printed wiring board according to any one of claims 6 to 8,
characterized in forming a resist pattern for forming the wiring
lead-out port at a copper layer on one face of a cladding sheet for
the multiplayer printed wiring board according to any one of claims
6 to 8, thereafter carrying out selective etching of copper to
thereby form a shield wall of the wiring lead-out port, thereafter
successively coating an insulating resin on an etching face,
thereafter etching a copper layer on a rear face of the cladding
sheet to thereby form a circuit shield wall, forming a signal
circuit by etching the intermediary silver layer and coating an
insulating resin on an etching face.
Description
TECHNICAL FIELD
[0001] The present invention relates to a structure of a multi
layer printed wiring board, a cladding sheet used therefor and a
method of manufacturing a multi layer printed wiring board having
the structure, particularly to an electric circuit connector of a
connector pin or the like.
BACKGROUND OF THE INVENTION
[0002] In recent years, by highly integrated formation and high
speed formation of a semiconductor device, small-sized formation
and high function formation of an electronic apparatus have been
progressed. The high speed formation of an electronic apparatus
seems to further develop in the future, however, according to a
circuit of a high frequency wave exceeding 50 MHz, there pose
various problems owing to electric characteristics of wirings. For
example, although a microstrip structure has widely been used
conventionally as a wiring structure of a high frequency wave
circuit, in accordance with small-sized formation and high function
formation of an electronic apparatus, a wiring pattern width is
reduced and according to a microstrip structure, it has been
difficult to restrain crosstalk noise generated among wirings.
Further, high speed formation of a signal help increase crosstalk
noise and it is difficult to restrain crosstalk noise in a
microstrip wiring structure.
[0003] As a constitution aiming to resolve the above-described
problem, there is a proposal of Japanese Patent Laid-Open No.
283930/1997. The proposal is a multilayer printed wiring board
comprising a film adhering base material laminatedly constituted by
a copper-clad laminated sheet formed with an earth circuit
conductor and a film-like copper-clad laminated sheet formed with
an earth circuit conductor and a signal circuit conductor, and a
through hole, forming a coaxial circuit structure on the wiring
board. By constructing such a constitution, there can be formed a
coaxial circuit having a strip structure in which the signal
circuit conductor is completely covered by the earth circuit
conductor and a via hole for interlayer connection between inner
layers can also be provided and there can be provided a multilayer
printed wiring board constituting a high speed signal transmission
line which is not effected with influence of radiated noise or
crosstalk noise.
[0004] The multilayer printed wiring board is provided with a hole
of through hole for interlayer connection. According to a method of
manufacturing the multilayer printed wiring board, firstly, a
copper-clad laminated sheet formed with an earth circuit conductor
and a film-like copper-clad laminated sheet formed with an earth
circuit conductor and a signal circuit conductor, are fabricated
separately from each other, and laminated to each other to thereby
construct a constitution of an integrated-type circuit structure of
a coaxial structure and by perforating the structure for
constituting a through hole and inserting a short circuit pin
provided with a contact point into a necessary one of the through
hole, an apparatus board or the like can be set and a via hole for
interlayer connection between inner layers is formed not by
perforating but by copper plating and etching treatment.
[0005] However, according to the method of Japanese Patent
Laid-Open No. 283930/1997, it is necessary to form a hole having a
diameter equivalent to a diameter of a land of the copper-clad
laminated sheet in a nonreflow type prepreg. Further, in laminating
and integrating the copper-clad laminated sheet formed with the
through hole and the nonreflow type prepreg formed with the hole,
there poses a problem that it is necessary to match positions of
the through hole of the copper-clad laminated sheet and the hole of
the nonreflow type prepreg.
[0006] It is an object of the invention to resolve the
above-described problem of the conventional technology and provide
a manufacturing method capable of manufacturing a multilayer
printed wiring board by simple and convenient steps and capable of
manufacturing the multilayer printed wiring board inexpensively by
mass production. Further, it is other object of the invention to
provide a manufacturing method capable of efficiently forming a
wiring lead-out port of a multilayer printed wiring board.
DISCLOSURE OF THE INVENTION
[0007] In order to achieve the above-described object, the
inventors have finished the invention by reaching a conclusion that
it is mostly preferable to adopt a manufacturing method of
manufacturing a total of a wiring board by an etching treatment and
providing a wiring lead-out port at the stage.
[0008] That is, a multilayer printed wiring board according to the
invention is characterized in including a signal circuit conductor
completely covered by an earth circuit at an inner portion thereof
as well as providing a lead-out port.
[0009] According to the invention, it is not necessary to carry out
a complicated processing of laminating a necessary number of
temporarily laminated articles and integrating the articles by
carrying out the actual lamination and therefore, it is not
necessary to form a hole having a diameter equivalent to a diameter
of a land of a copper-clad laminated board at a nonreflow type
prepreg, further, it is not necessary to carry out a complicated
processing of confirming whether positions of a through hole of the
copper-clad laminated board previously fabricated and the hole of
the nonreflow type prepreg coincide with each other thereafter and
therefore, the wiring lead-out port can easily be formed and a
large amount of products can easily be processed with good
dimension reproducibility.
[0010] According to the multilayer printed wiring board, it is
preferable that the signal circuit conductor includes a branch
pattern.
[0011] Further, a method of fabricating a multilayer printed wiring
board according to the invention is characterized in forming a
signal circuit conductor completely covered by an earth circuit and
a wiring lead-out port at an inner portion thereof by selective
etching of copper with regard to a cladding sheet for the
multilayer printed wiring board manufactured by bringing a copper
foil material and a nickel foil material into press contact with
each other by a reduction of 0.1 to 3%.
[0012] According to the manufacturing method, it is preferable that
the cladding sheet for the multilayer printed wiring board
comprises five layers of copper/nickel/copper/nickel/copper.
[0013] Further, according to the manufacturing method, it is
preferable that the cladding sheet for the multiplayer printed
wiring board is manufactured by bringing the copper foil material
provided with nickel plating at one face or two faces thereof and
other copper foil material or a copper foil material provided with
nickel plating at one face thereof into press contact with each
other by the reduction of 0.1 to 3%.
[0014] Further, a method of fabricating a multilayer printed wiring
board according to the invention is characterized in forming a
signal circuit conductor completely covered by an earth circuit at
an inner portion thereof by selective etching of copper with regard
to a cladding sheet for the multilayer printed wiring board
manufactured by bringing a copper foil material and a silver foil
material into press contact with each other by a reduction of 0.1
to 3%.
[0015] According to the manufacturing method, it is preferable that
the cladding sheet for the multilayer printed wiring board
comprises three layers of copper/silver/copper.
[0016] Further, according to the manufacturing method, it is
preferable that the cladding sheet for the multilayer printed
wiring board is manufactured by bringing a copper foil material
provided with silver plating at one face thereof and other copper
foil material into press contact with each other by a reduction of
0.1 to 3%.
[0017] Further, it is preferable that the manufacturing method is
carried out by forming a resist pattern for forming a circuit
shield wall and for forming a wiring lead-out port at the copper
layer on the one face of the cladding sheet for the multilayer
printed wiring board, thereafter carrying out selective etching of
copper to thereby form the circuit shield wall and the wiring
lead-out port, removing the nickel layer, successively coating an
insulating resin on an etching face, thereafter forming a resist
pattern for forming a circuit shield wall at a copper layer on a
rear face of the cladding sheet, thereafter carrying out selective
etching of copper to thereby form the circuit shield wall, etching
the intermediate copper layer to thereby form a signal circuit,
coating an insulating resin on an etching face and plating copper
on two faces thereof to thereby form the shield wall.
[0018] Further, it is preferable that the manufacturing method is
carried out by forming a resist pattern for forming a circuit
shield wall or for forming the wiring lead-out port at the copper
layer on one face of the cladding sheet with regard to the cladding
sheet for a multilayer printed wiring board, thereafter carrying
out selective etching of copper to thereby form the circuit shield
wall, successively coating an insulating resin on an etching face,
thereafter forming a resist pattern for forming a circuit shield
wall at the copper layer on a rear face of the cladding sheet,
thereafter carrying out selective etching of copper to thereby form
the circuit shield wall, forming a signal circuit by etching the
intermediary copper layer, coating an insulating resin on an
etching face and thereafer plating copper at other than a portion
for constituting a wiring lead-out port to thereby form the shield
wall.
[0019] Further, according to the manufacturing method, it is
preferable that the signal circuit conductor is constituted by a
shape including a branch pattern.
[0020] Further, a method of forming a wiring lead-out port in a
multilayer printed wiring board according to the invention is
characterized in forming a resist pattern for forming the wiring
lead-out port at a copper layer on one face of a cladding sheet for
a multilayer printed wiring board, thereafter carrying out
selective etching of copper to thereby form a shield wall of the
wiring lead-out port, removing a nickel layer, successively coating
an insulating resin on an etching face, thereafter etching a copper
layer on a rear face of the cladding sheet and coating an
insulating resin on an etching face.
[0021] Further, a method of forming a wiring lead-out port in a
multilayer printed wiring board according to the invention, is
characterized in forming a resist pattern for forming the wiring
lead-out port at a copper layer on one face of a cladding sheet for
the multiplayer printed wiring board, thereafter carrying out
selective etching of copper to thereby form a shield wall of the
wiring lead-out port, thereafter successively coating an insulating
resin on an etching face, thereafter etching a copper layer on a
rear face of the cladding sheet to thereby form a circuit shield
wall, forming a signal circuit by etching the intermediary silver
layer and coating an insulating resin on an etching face.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is an explanatory view of steps of a method of
manufacturing a multilayer printed wiring board according to the
invention and is a side view of a cladding sheet for the multilayer
printed wiring board.
[0023] FIG. 2 is an explanatory view of steps of a method of
manufacturing a multiple printed wiring board according to the
invention and is a side view when a resist is coated on a cladding
sheet for the multilayer printed wiring board.
[0024] FIG. 3 is an explanatory view of steps of a method of
manufacturing a multilayer printed wiring board according to the
invention and is a side view after selective etching of copper and
removing a nickel layer.
[0025] FIG. 4 is an explanatory view of steps of a method of
manufacturing a multilayer printed wiring board according to the
invention and is a side view when insulating resin is coated.
[0026] FIG. 5 is an explanatory view of steps of a method of
manufacturing a multilayer printed wiring board according to the
invention and is a side view when a resist is coated.
[0027] FIG. 6 is an explanatory view of steps of a method of
manufacturing a multilayer printed wiring board according to the
invention and is a side view after selective etching of copper and
removing a nickel layer.
[0028] FIG. 7 is an explanatory view of steps of a method of
manufacturing a multilayer printed wiring board according to the
invention and is a side view when a resist is coated.
[0029] FIG. 8 is an explanatory view of steps of a method of
manufacturing a multilayer printed wiring board according to the
invention and is a side view after copper etching.
[0030] FIG. 9 is an explanatory view of steps of a method of
manufacturing a multilayer printed wiring board according to the
invention and is a side view after coating insulating resin.
[0031] FIG. 10 is an explanatory view of steps of a method of
manufacturing a multilayer printed wiring board according to the
invention and is a side view after coating copper by electroless
plating.
[0032] FIG. 11 is an explanatory view of steps of a method of
manufacturing a multilayer printed wiring board according to the
invention and is a side view of a cladding sheet for a multilayer
printed wiring board.
[0033] FIG. 12 is an explanatory view of steps of a method of
manufacturing a multilayer printed wiring board according to the
invention and is a side view after coating a resist.
[0034] FIG. 13 is an explanatory view of steps of a method of
manufacturing a multilayer printed wiring board according to the
invention and is a side view after coating insulating resin and
coating a resist.
[0035] FIG. 14 is an explanatory view of steps of a method of
manufacturing a multilayer printed wiring board according to the
invention and is a side view after etching and coating insulating
resin.
[0036] FIG. 15 is an explanatory view of steps of a method of
manufacturing a multilayer printed wiring board according to the
invention and is a side view after plating copper by electroless
plating.
[0037] FIG. 16 is a perspective view of a portion of a wiring
lead-out port of a multilayer printed wiring board according to the
invention.
[0038] FIG. 17 is a plane view showing a resist pattern when a
wiring board branched in a multilayer printed wiring board
according to the invention is intended to form.
[0039] FIG. 18 is a three-dimensional view showing a state after
etching when a wiring board branched in a multilayer printed wiring
board according to the invention is intended to form.
[0040] FIG. 19 is a three-dimensional view showing an example of a
signal circuit of a wiring board branched in a multilayer printed
wiring board according to the invention.
[0041] FIG. 20 is a plane view showing an example of a signal
circuit of a wiring board branched in a multilayer printed wiring
board according to the invention.
[0042] FIG. 21 is a front sectional view of an apparatus of
manufacturing a cladding metal sheet according to the
invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0043] The invention provides a multilayer printed wiring board
characterized in including a signal circuit conductor completely
covered by an earth circuit at an inner portion thereof and
providing a wiring lead-out port. A multilayer printed wiring board
according to the invention can be manufactured as follows.
[0044] As a material of manufacturing a multilayer printed wiring
board, it is preferable to use a cladding sheet for a printed
wiring board.
[0045] As a cladding sheet for a printed wiring board, there can be
pointed out a cladding sheet comprising a combination of a copper
(Cu) foil material and a nickel (Ni) foil material, for example, a
constitution comprising five layers of Cu/Ni/Cu/Ni/Cu.
[0046] Further, other than the above-described, there can be
pointed out a cladding sheet comprising a combination of a copper
foil material and a silver (Ag) foil material. As an example of the
combination, for example, a constitution comprising Cu/Ag/Cu can be
pointed out. Further, it is preferable to use a constitution
manufactured by bringing a copper foil member provided with silver
plating on one face thereof and other copper foil member into press
contact with each other by a reduction of 0.1 to 3%.
[0047] Further, an explanation will be given of a multilayer
printed wiring board manufactured by constituting a material
thereof by the former cladding sheet comprising the combination of
a copper foil material and a nickel foil material as a first
embodiment of the invention and a multilayer printed wiring board
constituted by the latter cladding sheet comprising a copper foil
material and a silver foil material as a second embodiment of the
invention.
[0048] The two embodiments are basically common in view of a
manufacturing method and therefore, basically, an explanation will
be given of the first embodiment of the invention and thereafter,
with regard to the second embodiment of the invention, only a point
of difference therefrom will be pointed out.
[0049] Explaining an example of a structure of a multilayer printed
wiring cladding sheet according to the first embodiment of the
invention in reference to FIG. 1, both faces of a copper layer 14
for constituting a wiring layer (a thickness of which is preferably
10 to 100 .mu.m) comprising a copper foil, is bonded with etching
stopper layers 11 and 12 each comprising nickel plating (a
thickness of which is preferably 0.5 to 3 .mu.m) or a nickel foil
(a thickness of which is 5 to 10 .mu.m) to thereby form a core of a
base.
[0050] Further, outer sides of the two etching stopper layers are
further formed with copper foil material (a thickness of which is
preferably 10 to 100 .mu.m) layers 10 and 13. These form shield
walls.
[0051] Next, an explanation will be given of a method of
manufacturing the multilayer printed wiring board according to the
first embodiment of the invention.
[0052] First, by laminating nickel plating layers or nickel foil
layers for constituting the etching stopper layers 11 and 12 on the
two faces of the copper layer 14 for constituting an inner
conductor layer when the multilayer printed wiring board is
manufactured, to thereby manufacture a copper foil material having
nickel layers. Further, although in the following description, for
convenience of explanation, an explanation will be given by
pointing out a case of constituting a nickel plating layer, the
manufacturing can similarly be carried out also when a nickel foil
is used in place thereof.
[0053] The multilayer printed wiring board according to the first
embodiment can basically be manufactured by bringing a copper foil
material for constituting a conductor layer or the like and a
laminated member of a nickel foil material or nickel plating for
forming an etchings to player into cold rolled press contact with
each other by a reduction of 0.1 to 3%.
[0054] In cold rolled press contact, an activation treatment is
previously carried out for the respective materials. As previously
disclosed in Japanese Patent Laid-Open No. 224184/1989 by the
applicant, the activation treatment can be carried out as follows,
(1) under an extremely low pressure inert gas atmosphere of
1.33.times.10 to 1.33.times.10.sup.-2 Pa, (2) there is constituted
one electrode A by the copper foil and the nickel layer having a
bonding faces or the copper foil and the silver layer having
bonding face respectively grounded to earth, alternating current of
1 to 50 MHz is applied between the one electrode A and other
electrode B insulatively supported to thereby carry out glow
discharge, (3) further, an area of the electrode exposed in plasma
produced by the glow discharge is equal to or smaller than 1/3 of
the area of the electrode B and (4) the materials are subjected to
a sputter etching treatment.
[0055] Actually, for example, a nickel-plated copper foil material
is wound around a payoff reel 23 in a cladding sheet manufacturing
apparatus shown in FIG. 21. Further, the copper foil material 10
for constituting a columnar conductor 17 is wound around a payoff
reel 25. The nickel-plated copper foil material 11, 12 and the
copper foil material 14 are simultaneously paid off from the payoff
reels 23 and 25 and portions thereof are wound around electrode
rolls 27 and 28 projected into an etching chamber 26 and activated
by being subjected to sputter etching treatment at inside of the
etching chamber 26.
[0056] Thereafter, the materials are brought into cold rolled press
contact by a rolling unit 30 provided at inside of a vacuum tank 29
and a cladding sheet 31 for a semiconductor package unit having a
three layers structure is reeled by a reeling roll 32.
[0057] Next, the cladding sheet 31 for the semiconductor package
unit having the three layers structure is again wound around the
payoff reel 23. Further, a copper foil material 33 for constituting
the shield wall 18 (refer to FIG. 1) is wound around the payoff
reel 25. The cladding sheet 31 and the copper foil material 33 are
respectively paid off from the payoff reels 23 and 25 and portions
thereof are wound around the electrode rolls 27 and 28 projected
into the etching chamber 26 and activated by being subjected to the
sputter etching treatment at inside of the etching chamber 26. Also
in this case, the activation treatment is carried out under a
condition similar to the above-described.
[0058] A cladding sheet 34 for a printed wiring board having the
five layers structure according to the first embodiment of the
invention is provided in this way as shown by FIG. 1.
[0059] Further, by repeatedly carrying out press contact by using
the above-described facility, there can be manufactured the
cladding sheet of multiple layers provided with the copper layers
at a surface layer and a rear face layer thereof and interposed
with the nickel layers at intermediate layers thereof in an order
of copper/nickel/copper/nickel/co- pper.
[0060] Further, by providing three pieces or more of the payoff
reels, installing the copper foil material, the nickel foil
material and the like at these reels and receiving supply of the
foil materials simultaneously from three pieces or more of the
reels, a cladding sheet having a multilayer structure can be
manufactured by a single time of press contact.
[0061] Further, with regard to the cladding sheet for a printed
wiring board comprising the copper foil material and the silver
foil material according to the second embodiment of the invention,
there is shown an example of a constitution comprising three layers
of copper/silver/copper. The constitution is also manufactured by
bringing the copper foil material for forming a conductor layer or
the like and the silver foil material or a silver plating laminated
member into cold rolled press contact by a reduction of 0.1 to 3%
and the cladding sheet can be manufactured similar to the cladding
sheet according to the first embodiment.
[0062] The cladding sheet for the multilayer printed wiring board
formed in this way, is made to constitute the multilayer printed
wiring board having a signal circuit conductor completely covered
by an earth circuit at an inner portion thereof by cutting the
cladding sheet into a desired size and selectively etching
copper.
[0063] The selectively etching can be carried out to form a desired
circuit. Therefore, the board cannot only be formed with a circuit
of a straight line but also a circuit having complicated
branching.
[0064] An explanation will be given of the case of the multiplayer
printed wiring board according to the first embodiment of the
invention, that is, a case of using the cladding sheet of five
layers of copper, nickel, copper, nickel and copper material of
FIG. 1 as a raw material.
[0065] First, selective etching of the copper foil material 10 is
carried out and the copper foil material 10 is dissolved and
removed while leaving the columnar conductor 17. Successively, an
etching solution is changed to a nickel etching solution and the
nickel layer 11 is removed. A state after removal is shown by FIG.
3. Further, the columnar conductor 17 which remains at the time
point constitutes a shield wall or the wiring lead-out port.
[0066] As the etching solution of the copper foil material, it is
preferable to use an aqueous solution of sulfuric acid+hydrogen
peroxide or an aqueous solution of persuifuric acid hydrogen
ammonium, further, as the nickel etching solution, it is preferable
to use, for example, Melstrip N-950 of Meltex Corp. or the like on
sale.
[0067] Further, although the etching treatment is carried out by
dipping a treated object in the etching aqueous solution, the
etching treatment may be carried out by spraying the etching
aqueous solution or dropping the aqueous solution onto an etched
face. In the case of spraying or dropping the etching solution, it
is sufficient that a resist treatment is carried out by a method of
subjecting only an uppermost layer to spinner coating. When the
etching treatment is carried out by dipping the object in the
etching solution, the object is dipped to etch in a bath of the
etching solution at 50.degree. C. for about 1 to 10 minutes,
however, with regard to individual bath temperature and dipping
time, optimum conditions can be determined depending on an amount
of operation, a time period or the like.
[0068] Next, an insulating resin layer 18 is formed by coating
insulating resin at voids after the etching treatment, a surface
thereof is polished and a surface of the columnar conductor layer
17 is exposed (FIG. 4). As the insulating resin in this case, epoxy
resin, polyimide resin or the like can be used.
[0069] Meanwhile, a photoresist similar to the above-described is
coated on a surface of the copper foil material 13 on a side
opposed to the face at which the copper foil material 10 has been
present (refer to FIG. 5) Here, it is important that the resist is
not coated on a portion for forming a wiring lead-out port in
finishing the object.
[0070] Successively, selective etching of the copper foil material
13 is carried out, the copper foil material is dissolved and
removed while leaving the columnar conductor layer 17, further, the
etching solution is changed and also the nickel layer 12 is removed
(FIG. 6). The portion of constituting the columnar conductor 17 in
this case, finally forms the shield wall (refer to notation 21 of
FIG. 10). Further, the etching solutions similar to those at the
previous time can be used.
[0071] Next, as shown by FIG. 7, a photoresist is coated one more
time. At this occasion, the resist is coated also at a portion for
constituting the wiring lead-out port. Successively, the object is
exposed and developed and thereafter, the intermediate copper layer
14 is removed by selective etching as shown by FIG. 8. The etching
solution in this case is similar to the above-described.
[0072] After selective etching of the intermediate copper layer has
been finished, voids after etching are filled with insulating resin
comprising epoxy resin, polyimide resin or the like similar to that
in the previous time, the resin layer 18 is formed (refer to FIG.
9), successively, surface polishing is carried out to thereby
expose the surface of the columnar conductor 17. Further, an upper
layer of an exposed portion of the columnar conductor for forming a
signal circuit, is coated with a photoresist layer 16, exposed and
developed.
[0073] Next, as shown by FIG. 10, a total except the wiring
lead-out port portion, is covered by an electroless copper plating
layer 19 to thereby constitute the shield wall. In this way, there
is finished the multilayer printed wiring board formed with the
signal circuit conductor completely covered by the earth circuit
and the lead-out port at an inner portion thereof.
[0074] Next, an explanation will be given of a case of a board of
three layers according to the second embodiment of the invention.
Except that the cladding sheet is constituted by three layers, by
carrying out selective etching of copper similar to the case of the
first embodiment, there can be manufactured the multilayer printed
wiring board formed with the signal circuit conductor completely
covered by the earth circuit at an inner portion thereof.
[0075] Although treating operation of the three layers board is
basically the same as in the case of the five layers board
according to the first embodiment, since the etching stopper layer
is not present, the step of removing the etching stopper layer can
be saved.
[0076] First, the cladding sheet having the three layer structure
as shown by FIG. 11 is prepared and as shown by FIG. 12, after
forming the photoresist film 16 on the surface of the copper foil
material 10, the object is exposed and developed.
[0077] Next, selective etching of the copper foil material 10 is
carried out and the copper foil material 10 is dissolved and
removed while leaving the columnar conductor 17. Successively,
insulating resin is coated and filled in voids after the etching
treatment to form the insulating layer 18, further, a surface
thereof is polished and a surface of the columnar conductor 17 is
exposed. The state is shown by FIG. 13. As insulating resin, epoxy
resin, polyimide resin or the like is used.
[0078] Thereafter, the photoresist 16 is coated on the surface of
the copper foil material 13 on other face similar to the first
embodiment except the portion of the wiring lead-out port (refer to
FIG. 13) selective etching of the copper foil material 13 is
carried out, successively, selective etching of the silver foil
material 15 is carried out by using an aqueous solution of ferric
nitrate as the etching solution and the copper foil material and
the silver foil material are dissolved and removed while leaving
the columnar conductor 17 (refer to FIG. 14).
[0079] Finally, as shown by FIG. 15, voids after etching are filled
with insulating resin comprising epoxy resin or polyimide resin
similar to that in the previous time to thereby form the insulating
resin layer 18 (refer to FIG. 14), electroless copper plating is
carried out to a total of the element and the total is covered by a
copper material while leaving a signal circuit forming portion to
thereby constitute the shield wall (refer to FIG. 15).
[0080] In this way, the multilayer printed wiring board according
to the invention provided with the wiring lead-out port is
manufactured (refer to FIG. 16).
[0081] When a board for a signal wiring in a branch pattern is
intended to manufacture, in compliance with a desired wiring shape,
a resist pattern is drawn in the above-described manufacturing
steps. For example, when a board for a wiring in a T-like shape is
intended to manufacture, after drawing a resist pattern as shown by
FIG. 17 on the copper foil material, by carrying out selective
etching, a shield wall as shown by FIG. 18 is provided. Further,
when the steps are successively processed, a signal circuit having
a desired T-like shape is formed (refer to FIG. 19, FIG. 20). By
the principle, not only the T-like circuit but also a complicated
circuit can easily be formed.
INDUSTRIAL APPLICABILITY
[0082] The multilayer printed wiring board according to the
invention can easily be manufactured by the simple method of
repeating the etching treatment by using the cladding sheet of a
plurality of layers provided by press bonding. Further, wiring
lead-out port can easily be provided and a large amount of products
can easily be manufactured with good size reproducibility.
Particularly, even the multilayer printed wiring board having a
complicated wiring structure can easily be manufactured and
therefore, the invention is industrially useful.
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