U.S. patent application number 13/023222 was filed with the patent office on 2011-06-09 for adhesive for connection of circuit member and semiconductor device using the same.
This patent application is currently assigned to HITACHI CHEMICAL COMPANY, LTD.. Invention is credited to Akira NAGAI.
Application Number | 20110133346 13/023222 |
Document ID | / |
Family ID | 39608699 |
Filed Date | 2011-06-09 |
United States Patent
Application |
20110133346 |
Kind Code |
A1 |
NAGAI; Akira |
June 9, 2011 |
ADHESIVE FOR CONNECTION OF CIRCUIT MEMBER AND SEMICONDUCTOR DEVICE
USING THE SAME
Abstract
An adhesive for connecting circuit members, which is interposed
between a semiconductor chip having protruding connecting terminals
and a board having wiring patterns formed thereon for electrically
connecting the connecting terminals and the wiring patterns facing
each other and bonding the semiconductor chip and the board by
applying pressure/heat, containing a resin composition containing a
thermoplastic resin, a crosslinkable resin and a hardening agent
for forming a crosslink structure of the crosslinkable resin; and
composite oxide particles dispersed in the resin composition.
Inventors: |
NAGAI; Akira; (Ibaraki,
JP) |
Assignee: |
HITACHI CHEMICAL COMPANY,
LTD.
Tokyo
JP
|
Family ID: |
39608699 |
Appl. No.: |
13/023222 |
Filed: |
February 8, 2011 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12500114 |
Jul 9, 2009 |
|
|
|
13023222 |
|
|
|
|
PCT/JP2008/050140 |
Jan 9, 2008 |
|
|
|
12500114 |
|
|
|
|
Current U.S.
Class: |
257/783 ;
252/519.33; 257/E23.01 |
Current CPC
Class: |
H01L 2924/01058
20130101; H01L 2924/01059 20130101; C09J 163/00 20130101; H01L
2924/09701 20130101; H01L 2924/15788 20130101; H01L 2224/9211
20130101; C08K 3/08 20130101; C08K 3/22 20130101; H01L 2224/13144
20130101; H01L 2924/01072 20130101; H01L 2224/29369 20130101; H01L
2224/05111 20130101; H01L 2224/73104 20130101; H01L 24/32 20130101;
H01L 2924/0103 20130101; H01L 2224/29344 20130101; H01L 2224/83101
20130101; H01L 2924/01027 20130101; H01L 2924/01047 20130101; H01L
2924/01077 20130101; H01L 2924/07802 20130101; H01L 2224/83851
20130101; H01L 2924/01078 20130101; H01L 2224/83191 20130101; H01L
2924/07811 20130101; H01L 2924/01049 20130101; H01L 2924/0107
20130101; H01L 2224/05639 20130101; C08L 2666/28 20130101; H01L
24/16 20130101; H01L 2924/01056 20130101; H01L 2924/01013 20130101;
H01L 2224/05164 20130101; H01L 2924/01012 20130101; H01L 2924/01042
20130101; H01L 2224/73204 20130101; H01L 2224/81903 20130101; H01L
24/05 20130101; H01L 2924/01019 20130101; H01L 2924/01033 20130101;
H01L 2924/0105 20130101; H01L 2924/01068 20130101; H01L 2924/01084
20130101; H01L 24/29 20130101; H01L 2924/01005 20130101; H01L
2924/01038 20130101; H01L 2924/01082 20130101; H01L 2924/01025
20130101; H01L 2924/01079 20130101; H01L 2924/01015 20130101; H01L
2224/05139 20130101; H01L 2224/90 20130101; H01L 2924/01044
20130101; H01L 2924/01057 20130101; H01L 2924/01076 20130101; H01L
2224/2929 20130101; H01L 2924/0102 20130101; H01L 2924/0104
20130101; H01L 2224/29339 20130101; H01L 2924/01011 20130101; H01L
2924/01029 20130101; H01L 2924/01045 20130101; H01L 2224/0558
20130101; H01L 2224/1134 20130101; H01L 2924/01041 20130101; H01L
2924/01066 20130101; H01L 2224/32225 20130101; H01L 2224/05144
20130101; H01L 2224/05147 20130101; H01L 2224/05655 20130101; H01L
2924/01074 20130101; H01L 2924/01004 20130101; H01L 2924/01006
20130101; H01L 2924/01063 20130101; H01L 2224/05644 20130101; H01L
2224/05647 20130101; H01L 24/83 20130101; H01L 2224/05611 20130101;
H01L 2224/05664 20130101; H01L 2924/01046 20130101; H01L 2924/01051
20130101; H01L 2224/16238 20130101; H01L 2924/01023 20130101; H01L
2924/014 20130101; C09J 11/04 20130101; H01L 24/90 20130101; H01L
2224/05155 20130101; H01L 2924/01073 20130101; H01L 2924/01024
20130101; H01L 2924/01077 20130101; H01L 2924/00011 20130101; H01L
2224/73204 20130101; H01L 2224/16225 20130101; H01L 2224/32225
20130101; H01L 2924/00 20130101; H01L 2224/83191 20130101; H01L
2224/83101 20130101; H01L 2924/00 20130101; H01L 2924/3512
20130101; H01L 2924/00 20130101; H01L 2224/29339 20130101; H01L
2924/00014 20130101; H01L 2224/29344 20130101; H01L 2924/00014
20130101; H01L 2224/29369 20130101; H01L 2924/00014 20130101; H01L
2224/2929 20130101; H01L 2924/0665 20130101; H01L 2924/00014
20130101; H01L 2224/9211 20130101; H01L 2224/81 20130101; H01L
2224/83 20130101; H01L 2924/07802 20130101; H01L 2924/00 20130101;
H01L 2924/07811 20130101; H01L 2924/00 20130101; H01L 2924/15788
20130101; H01L 2924/00 20130101; H01L 2224/13144 20130101; H01L
2924/00014 20130101; H01L 2224/05611 20130101; H01L 2924/00014
20130101; H01L 2224/05639 20130101; H01L 2924/00014 20130101; H01L
2224/05644 20130101; H01L 2924/00014 20130101; H01L 2224/05647
20130101; H01L 2924/00014 20130101; H01L 2224/05655 20130101; H01L
2924/00014 20130101; H01L 2224/05664 20130101; H01L 2924/00014
20130101; H01L 2224/05111 20130101; H01L 2924/00014 20130101; H01L
2224/05139 20130101; H01L 2924/00014 20130101; H01L 2224/05144
20130101; H01L 2924/00014 20130101; H01L 2224/05147 20130101; H01L
2924/00014 20130101; H01L 2224/05155 20130101; H01L 2924/00014
20130101; H01L 2224/05164 20130101; H01L 2924/00014 20130101; C09J
163/00 20130101; C08L 2666/28 20130101 |
Class at
Publication: |
257/783 ;
252/519.33; 257/E23.01 |
International
Class: |
H01L 23/48 20060101
H01L023/48; H01B 1/12 20060101 H01B001/12 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 10, 2007 |
JP |
P2007-002308 |
Claims
1. An adhesive for connecting circuit members, which is interposed
between a semiconductor chip having protruding connecting terminals
and a board having wiring patterns formed thereon for electrically
connecting the connecting terminals and the wiring patterns facing
each other and bonding the semiconductor chip and the board by
applying pressure/heat, the adhesive comprising: (a) a resin
composition comprising a thermoplastic resin, a crosslinkable resin
and a hardening agent for forming a crosslink structure of the
crosslinkable resin; and (b) composite oxide particles dispersed in
the resin composition, wherein the thermoplastic resin is a
copolymerizable resin having a weight average molecular weight of 1
million or less and a glass transition temperature of 40.degree. C.
or less, and having a reactive functional group with the
crosslinkable resin in a side chain, wherein the crosslinkable
resin is an epoxy resin, and wherein the hardening agent is a
microencapsulated hardening agent.
2. The adhesive for connecting circuit members according to claim
1, wherein a refractive index difference between the resin
composition and the composite oxide particles falls within
.+-.0.06.
3. (canceled)
4. The adhesive for connecting circuit members according to claim
1, wherein the composite oxide particles are particles formed of at
least one type of metal element selected from aluminum and
magnesium, and an oxide comprising a metal element except the metal
elements or a metalloid element.
5. The adhesive for connecting circuit members according to claim
4, wherein the metalloid element is silicon and/or boron.
6. The adhesive for connecting circuit members according to claim
1, wherein the composite oxide particles are particles comprising a
composite oxide having a specific gravity of 4 or less.
7. (canceled)
8. The adhesive for connecting circuit members according to claim
1, wherein the composite oxide particles are composite oxide
particles having an average particle size of 15 .mu.m or less.
9. (canceled)
10. The adhesive for connecting circuit members according to claim
1, wherein a visible-light parallel transmittance in an unhardened
state is 15 to 100%.
11. The adhesive for connecting circuit members according to any
one of claim 1, wherein a reactivity obtained after heating at
180.degree. C. for 20 seconds and measured by a differential
scanning calorimeter is 80% or more.
12. The adhesive for connecting circuit members according to claim
1, wherein a linear expansion coefficient measured at 40.degree. C.
to 100.degree. C. after hardening is 70.times.10-6/.degree. C. or
less.
13. (canceled)
14. The adhesive for connecting circuit members according to claim
1, the adhesive further comprising (c) conductive particles having
an average particle size of 3 to 5 .mu.m dispersed therein.
15. A semiconductor device comprising: (i) an electronic component
comprising a semiconductor chip having connecting terminals; and
(ii) a board having wiring patterns formed thereon are electrically
connected by the adhesive for connecting circuit members according
to claim 1.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a Continuation Application of PCT application No.
PCT/JP2008/050140, filed on Jan. 9, 2008.
[0002] This application is based upon and claims the benefit of
priority from prior Japanese Patent Application No. 2007-002308,
filed Jan. 10, 2007, the entire contents of which are incorporated
herein by reference.
TECHNICAL FIELD
[0003] The present invention relates to an adhesive for connecting
circuit members and a semiconductor device using the same. More
specifically, the present invention relates to a circuit-member
connecting adhesive for connecting semiconductor elements to a
circuit board in accordance with a face-down bonding system with
application of heat and pressure, a circuit-member connecting
adhesive (circuit-member connecting anisotropic conductive
adhesive) having conductive particles dispersed therein and a
semiconductor device using these.
BACKGROUND ART
[0004] Generally, as a system for directly mounting semiconductor
chips (hereinafter sometimes simply referred to "chips") on a
circuit board in accordance with a face-down bonding system, a
system in which solder bumps are formed on electrode portions of
semiconductor chips, which are connected to a circuit board by
soldering, and a method in which a conductive adhesive is applied
to protruding electrodes provided to semiconductor chips for
electrically connecting to circuit-board electrodes, are known.
[0005] These systems have problems. When a chip and a board are
exposed to various environments, stress is produced in the
connection interface ascribed to a difference in thermal expansion
coefficient between the chip and the board to be connected, with
the result that connection reliability decreases. Therefore, in
order to reduce the stress in the connection interface, a system
for filling the gap between the chip and the board generally with
an underfill material such as an epoxy resin has been studied.
[0006] As a filling system with the underfill material, mention may
be made of a system in which a chip and a board are connected and
thereafter a low-viscosity liquid resin is injected and a system in
which an underfill material is placed on a board and then a chip is
mounted. In the meantime, as a method in which an underfill
material is previously placed on a board and then a chip is
mounted, a method of applying a liquid resin and a method of
attaching a resin film are known.
[0007] However, in the case of applying a liquid resin, it is
difficult to accurately control the application amount by a
dispenser. In the context of a recent tendency toward thin-film
chip, the resin, if excessively applied, runs off from a chip in a
bonding process, moves up along the side surface of the chip and
contaminates a bonding tool. Because of this, a tool washing step
must be added, complicating a process at the time of a large-scale
production.
[0008] Alternatively, in the case of bonding a resin film, it is
easy to supply an optimum amount of resin by controlling the
thickness of the resin; however, when the film is bonded to a
board, a step of bonding the film called a provisional
pressure-bonding step is required. In the provisional
pressure-bonding step, a reel tape having slits at the intervals
larger than the width of a target chip is used. The adhesive
present on the base material of the reel tape is cut in half
depending upon the size of the chip and bonded to the board by
thermocompression bonding at such a temperature that an adhesive
does not react.
[0009] Since the accuracy of supplying the film to a chip mounting
position is low, generally a larger film than a chip size is bonded
in the provisional pressure-bonding in order to keep yield.
Accordingly, enough distance is required to an adjacent component,
impeding high-density packaging. On the other hand, thin-width reel
processing dealing with microchips, etc. is difficult. It is still
necessary to bond a larger film than a chip size to deal with this
case. An extra mounting area is required.
[0010] In the context, a method for supplying the same-size
adhesive as a chip size is proposed. In this method, an adhesive is
supplied in the stage of a wafer and then processed simultaneously
with chips by dicing or the like to obtain chips attached with the
adhesive (see, for example, Patent Documents 1, 2).
[0011] Patent Document 1: Japanese Patent No. 2833111
[0012] Patent Document 2: Japanese Patent Application Laid-Open No.
2006-049482
DISCLOSURE OF THE INVENTION
Problem to be Solved by the Invention
[0013] However, the preset underfill method on a wafer so far
proposed has the following problems and not commonly used in the
market. For example, in the method of Patent Document 1, an
adhesive film is attached to a wafer and thereafter the wafer is
diced into discrete pieces to obtain chips with the adhesive
film.
[0014] According to this method, a wafer/adhesive/separator
laminate is prepared and cut, and thereafter, the separator is
peeled off to obtain chips attached with an adhesive. However, this
method has a problem in that the adhesive and the separator are
dissociated in cutting the laminate, with the result that discrete
semiconductor chips scatter and run off.
[0015] Second, Patent Document 2 provides a method concerning a
wafer processing tape having a sticky layer and an adhesive layer
in which a wafer is bonded to a wafer processing tape and diced,
and then, discrete chips picked up are connected to a board by
flip-chip.
[0016] However, generally in flip-chip mounting, terminals called
bumps formed on the circuit surface of a chip are connected to the
corresponding terminals on a board. For this purpose, an alignment
mark on the chip is aligned with an alignment mark on the board by
a flip-chip bonder and then bonded. However, when an adhesive is
applied on the circuit surface of a chip, the adhesive covers the
alignment mark of the circuit surface, impeding alignment. This is
a problem. However, Patent Document 2 does not provide any solution
to deal with this problem.
[0017] On the other hand, a technique for obtaining transparency of
a resin is described in the specification of Japanese Patent No.
3408301. That is an anisotropic conductive film containing
conductive particles and transparent glass particles dispersed in
an insulating adhesive and an adhesive. However, since the glass
particles are amorphous and thus have a large linear expansion
coefficient, it is thus difficult to attain a low linear expansion
coefficient required as a property after the flip-chip
mounting.
[0018] In the context, an object of the present invention is to
provide a circuit-member connecting adhesive, which has excellent
adhesiveness to a wafer in an unhardened state, through which an
alignment mark provided to the wafer is highly recognizable, and
has excellent adhesiveness and connection reliability between a
chip and a board in a hardened state, and provide a semiconductor
device using the same.
Means for Solving Problem
[0019] The present invention relates to the following items.
[0020] (1) An adhesive for connecting circuit members, which is
interposed between a semiconductor chip having protruding
connecting terminals and a board having wiring patterns formed
thereon for electrically connecting the connecting terminals and
the wiring patterns facing each other and bonding the semiconductor
chip and the board by applying pressure/heat, in which
[0021] the adhesive for connecting circuit members contains
[0022] a resin composition comprising a thermoplastic resin, a
crosslinkable resin and a hardening agent for forming a crosslink
structure of the crosslinkable resin; and
[0023] composite oxide particles dispersed in the resin
composition.
[0024] (2) The adhesive for connecting circuit members according to
item (1), in which the refractive index difference between the
resin composition and the composite oxide particles falls within
.+-.0.06.
[0025] (3) The adhesive for connecting circuit members according to
item (1) or (2), in which the composite oxide particles have a
refractive index of 1.5 to 1.7 and are particles formed of a
composite oxide comprising two or more types of metal elements.
[0026] (4) The adhesive for connecting circuit members according to
any of items (1) to (3), in which the composite oxide particles are
particles formed of at least one type of metal element selected
from aluminum and magnesium, and an oxide comprising a metal
element except the above metal elements or a metalloid element.
[0027] (5) The adhesive for connecting circuit members according to
item (4), in which the metalloid element is silicon and/or
boron.
[0028] (6) The adhesive for connecting circuit members according to
any of items (1) to (5), in which the composite oxide particles are
particles comprising a composite oxide having a specific gravity of
4 or less.
[0029] (7) An adhesive for connecting circuit members, which is
interposed between a semiconductor chip having protruding
connecting terminals and a board having wiring patterns formed
thereon for electrically connecting the connecting terminals and
the wiring patterns facing each other and bonding the semiconductor
chip and the board by applying pressure/heat, in which
[0030] the adhesive for connecting circuit members contains
[0031] a resin composition containing a thermoplastic resin, a
crosslinkable resin and a hardening agent for forming a crosslink
structure of the crosslinkable resin; and
[0032] composite oxide particles comprising cordierite particles
dispersed in the resin composition.
[0033] (8) The adhesive for connecting circuit members according to
any of items (1) to (7), in which the composite oxide particles are
composite oxide particles having an average particle size of 3
.mu.m or less.
[0034] (9) The adhesive for connecting circuit members according to
any of items (1) to (8), in which the composite oxide particles are
comprised in an amount of 25 to 200 parts by weight relative to 100
parts by weight of the resin composition.
[0035] (10) The adhesive for connecting circuit members according
to any of items (1) to (9), in which the adhesive for connecting
circuit members in an unhardened state has a visible-light parallel
transmittance of 15 to 100%.
[0036] (11) The adhesive for connecting circuit members according
to any of items (1) to (10), in which a reactivity of the adhesive
for connecting circuit members measured by a differential scanning
calorimeter (DSC) after heating at 180.degree. C. for 20 seconds is
80% or more.
[0037] (12) The adhesive for connecting circuit members according
to any of items (1) to (11), in which a linear expansion
coefficient of the adhesive for connecting circuit members measured
at 40.degree. C. to 100.degree. C. after hardening is
70.times.10.sup.-6/.degree. C. or less.
[0038] (13) The adhesive for connecting circuit members according
to any of items (1) to (12), in which the thermoplastic resin is a
copolymerizable resin having a weight average molecular weight of 1
million or less and a glass transition temperature (Tg) of
40.degree. C. or less, and having a reactive functional group with
the crosslinkable resin in a side chain,
[0039] the crosslinkable resin is an epoxy resin, and
[0040] the hardening agent is a microencapsulated hardening
agent.
[0041] (14) The adhesive for connecting circuit members according
to any of items (1) to (13), comprising conductive particles having
an average particle size of 3 to 5 .mu.m dispersed therein.
[0042] (15) A semiconductor device comprising an electronic
component in which a semiconductor chip having connecting terminals
and a board having wiring patterns formed thereon are electrically
connected by the adhesive for connecting circuit members according
to any of items (1) to (14).
Effect of the Invention
[0043] The present invention provides a circuit-member connecting
adhesive, which has excellent adhesiveness to a wafer in an
unhardened state, through which an alignment mark provided to the
wafer is highly recognizable, and has excellent adhesiveness and
connection reliability between a chip and a board in a hardened
state, and provides a semiconductor device using the same. More
specifically, there is provided a circuit-member connecting
adhesive optimized for satisfying the following properties:
compatibility between peel-off suppression during dicing and simple
release after dicing by optimizing the adhesiveness to a wafer and
the adhesiveness to a dicing tape; high elasticity of a film in an
unhardened state in order to perform dicing while suppressing
occurrence of fibrous burr and crack, etc.; visibility of an
alignment mark through a resin, which enables accurate alignment of
a diced adhesive chip with a circuit board; a high reactivity,
which enables hardening at low temperature for short time in a chip
mounting process; and a high connection reliability attained by
lowering thermal expansion by a large content of filler. In
addition, there is provided an anisotropic conductive adhesive
wherein conductive particles are dispersed in the circuit-member
connecting adhesive and a semiconductor device using these
adhesives.
[0044] According to the circuit-member connecting adhesive of the
present invention, a semiconductor chip attached with an adhesive
can be obtained by a preset underfill method, which can deal with
narrow-pitch and narrow-gap tendency, without contamination during
a dicing process and without difficulty in peeling-off from a
dicing tape after the dicing process. In addition, not only
transparency, which enables accurate alignment of an adhesive chip
but also high connection reliability obtained by lowering a thermal
expansion coefficient can be obtained at the same time.
BRIEF DESCRIPTION OF THE DRAWINGS
[0045] FIG. 1 is a sectional view of a circuit-member connecting
adhesive according to a first embodiment;
[0046] FIG. 2 is a sectional view of a circuit-member connecting
adhesive according to a second embodiment;
[0047] FIG. 3 is a sectional view of a semiconductor chip having
protruding connecting terminals;
[0048] FIG. 4 is a sectional view of a board having wiring patterns
formed thereon;
[0049] FIG. 5 is a sectional view of an electronic component in
which a semiconductor chip and a board are electrically connected
and bonded by a circuit-member connecting adhesive according to the
first embodiment;
[0050] FIG. 6 is a sectional view of an electronic component in
which a semiconductor chip and a board are electrically connected
and bonded by a circuit-member connecting adhesive according to the
second embodiment;
[0051] FIG. 7 is a sectional view of an electronic component in
which a semiconductor chip and a board are electrically connected
and bonded by a circuit-member connecting adhesive according to the
second embodiment;
[0052] FIG. 8 is a sectional view illustrating an embodiment of a
manufacturing step of the electronic component shown in FIG. 5.
FIG. 8(a) is a sectional view of a laminate formed by laminating a
circuit-member connecting adhesive according to the first
embodiment on a semiconductor chip; and FIG. 8(b) is a sectional
view of the board;
[0053] FIG. 9 is a sectional view illustrating an embodiment of a
manufacturing step of the electronic component shown in FIG. 6 or
7. FIG. 9(a) is a sectional view of a laminate formed by laminating
a circuit-member connecting adhesive according to the second
embodiment on a semiconductor chip and FIG. 9(b) is a sectional
view of the board;
[0054] FIG. 10 is a sectional view of a semiconductor device having
an electronic component in which a semiconductor chip and a board
are electrically connected by a circuit-member connecting adhesive
according to the first embodiment; and
[0055] FIG. 11 is a view showing transmissivity of adhesives for
connecting circuit members.
DESCRIPTION OF SYMBOLS
[0056] 1 Circuit-member connecting adhesive according to the first
embodiment; 2 Circuit-member connecting adhesive according to the
second embodiment; 3 Semiconductor chip; 4 Board; 5 Electronic
component mounting board; 10 Adhesive; 12 Conductive particles; 20
Semiconductor component; 22, 42 Connecting terminal; 30, 40
Insulating board; 32 Wiring pattern; 34 Solder ball
BEST MODE FOR CARRYING OUT THE INVENTION
[0057] Referring to the accompanying drawings, preferred
embodiments will be described below. Note that identical symbols
are used to designate the same structural elements in the
description of the drawings and duplication of description is
avoided. Furthermore, the figures are partly exaggerated in order
to facilitate understanding and thus the dimensional ratios do not
always coincide with those used in the description.
[0058] FIG. 1 is a sectional view of a circuit-member connecting
adhesive according to a first embodiment and FIG. 2 is a sectional
view of a circuit-member connecting adhesive according to a second
embodiment.
[0059] The circuit-member connecting adhesive 1 according to the
first embodiment shown in FIG. 1 is a film adhesive constituted of
an adhesive 10, which is formed of a resin composition comprising a
thermoplastic resin, a crosslinkable resin and a hardening agent
and composite oxide particles dispersed in the resin
composition.
[0060] The circuit-member connecting adhesive 2 according to the
second embodiment shown in FIG. 2 is a film adhesive constituted of
the adhesive 10, which is formed of a resin composition comprising
a thermoplastic resin, a crosslinkable resin and a hardening agent
and composite oxide particles dispersed in the resin composition,
and conductive particles 12 dispersed in the adhesive 10, which are
3 to 5 .mu.m in average particle size.
[0061] FIG. 3 is a sectional view of a semiconductor chip having
protruding connecting terminals and to be joined by a
circuit-member connecting adhesive of the present invention. The
semiconductor chip 3 shown in FIG. 3 has a semiconductor component
20 and connecting terminals 22 formed so as to protrude on the main
surface.
[0062] FIG. 4 is a sectional view of a board having wiring patterns
formed thereon and to be joined by a circuit-member connecting
adhesive of the present invention. The board 4 shown in FIG. 4 has
an insulating board 30 and wiring patterns (electrode) 32 formed on
the main surface.
[0063] FIG. 5 is a sectional view of an electronic component in
which a semiconductor chip and a board are electrically connected
and bonded by a circuit-member connecting adhesive according to the
first embodiment. In the electronic component shown in FIG. 5, a
semiconductor chip 3, which has a semiconductor component 20 and
connecting terminals 22, and the board 4, which has the insulating
board 30 and the wiring patterns 32, are arranged such that the
connecting terminals 22 and the wiring patterns 32 face each other.
The semiconductor chip 3 and the board 4 are bonded by the
circuit-member connecting adhesive 1 according to the first
embodiment comprising the adhesive 10; at the same time, the
connecting terminals 22 and the wiring patterns 32 are brought into
contact with each other and electrically connected.
[0064] FIG. 6 is a sectional view of an electronic component in
which a semiconductor chip and a board are electrically connected
and bonded by a circuit-member connecting adhesive according to the
second embodiment. In the electronic component shown in FIG. 6, a
semiconductor chip 3, which has a semiconductor component 20 and a
connecting terminal 22, and a board 4, which has an insulating
board 30 and wiring patterns 32, are arranged such that the
connecting terminals 22 and the wiring patterns 32 face each other.
The semiconductor chip 3 and the board 4 are bonded by the
circuit-member connecting adhesive 2 according to the second
embodiment formed of the adhesive 10 and the conductive particles
12; at the same time, the connecting terminals 22 and the wiring
patterns 32 are brought into contact with each other and
electrically connected. Note that the conductive particles 12 are
present at positions causing no short circuit between the
connecting terminals 22 or between the wiring patterns 32.
[0065] FIG. 7 is a sectional view of an electronic component in
which a semiconductor chip and a board are electrically connected
and bonded by a circuit-member connecting adhesive according to the
second embodiment, and shows a different embodiment of the
electronic component shown in FIG. 6. In the electronic component
shown in FIG. 7, the semiconductor chip 3, which has a
semiconductor component 20 and connecting terminals 22, and the
board 4, which has an insulating board 30 and wiring patterns 32
are arranged such that the connecting terminals 22 and the wiring
patterns 32 face each other. The semiconductor chip 3 and the board
4 are bonded by a circuit-member connecting adhesive according to
the second embodiment comprising the adhesive 10 and the conductive
particles 12; at the same time, the connecting terminals 22 and the
wiring patterns 32 are brought into contact with each other with
conductive particles 12 interposed between them, and electrically
connected. Note that the conductive particles 12, which are not
involved in electrical connection, are present at positions causing
no short circuit between the connecting terminals 22 or the wiring
patterns 32.
[0066] FIG. 8 is a sectional view illustrating an embodiment of a
manufacturing step of the electronic component shown in FIG. 5.
FIG. 8(a) is a sectional view of a laminate formed by laminating a
circuit-member connecting adhesive according to the first
embodiment comprising the adhesive 10 on a semiconductor chip 3,
which has the semiconductor component 20 and the connecting
terminals 22, on the side having the connecting terminals 22. FIG.
8(b) is a sectional view of the board 4 having the insulating board
30 and the wiring patterns 32. As shown in FIG. 8, the laminate of
FIG. 8(a) and the board of FIG. 8(b) are subjected to
pressure-bonding such that the connecting terminals 22 and the
wiring patterns 32 face each other and the circuit-member
connecting adhesive 1 is heated under pressure to obtain the
electronic component shown in FIG. 5.
[0067] FIG. 9 is a sectional view illustrating an embodiment of a
manufacturing step of the electronic component shown in FIG. 6 or
7. FIG. 9(a) is a sectional view of a laminate formed by laminating
a circuit-member connecting adhesive 2 according to the second
embodiment on a semiconductor chip, which comprising the adhesive
10 and the conductive particles 12, on a semiconductor chip 3,
which has the semiconductor component 20 and the connecting
terminals 22, on the side having the connecting terminals 22. FIG.
9(b) is a sectional view of the board 4 having the insulating board
30 and the wiring patterns 32. As shown in FIG. 9, the laminate of
FIG. 9(a) and the board of FIG. 9(b) are subjected to
pressure-bonding such that the connecting terminals 22 and the
wiring patterns 32 face each other and the circuit-member
connecting adhesive 2 is heated under pressure to obtain the
electronic component shown in FIG. 6 or 7.
[0068] FIG. 10 is a sectional view of a semiconductor device having
an electronic component in which a semiconductor chip is
electrically connected to a board by a circuit-member connecting
adhesive according to the first embodiment. The semiconductor
device shown in FIG. 10 is composed of an electronic component and
an electric component mounting board for mounting the electronic
component. In the electronic component constituting the
semiconductor device of FIG. 10, the semiconductor chip 3, which
has the semiconductor component 20 and the connecting terminals 22,
and the board 4, which has the wiring patterns 32 on one of the
surfaces of the insulating board 30 and solder balls 34 on the
other surface, are arranged such that the connecting terminals 22
and the wiring patterns 32 face each other. The semiconductor chip
3 and the board 4 are bonded by the circuit-member connecting
adhesive 1 according to the first embodiment composed of the
adhesive 10; at the same time, the connecting terminals 22 and the
wiring patterns 32 are brought into contact with each other and
electrically connected. Note that the wiring patterns 32 and the
solder balls 34 are allowed to communicate by via holes (not shown)
formed within the insulating board 30. In short, the semiconductor
device shown in FIG. 10 is formed by electrically connecting the
aforementioned electronic component and the electronic component
mounting board 5, in which the connecting terminals 42 are formed
on an insulating board 40, such that solder balls 34 are positioned
on the connecting terminals 42 of the electronic component mounting
board 5.
[0069] In the present invention, the connecting terminal 22 to be
used in the semiconductor chip 3 is a gold stud bump formed of gold
wire, a metal ball fixed to the electrode of the semiconductor chip
by thermocompression bonding or by using a thermocompression
bonding machine in combination with ultrasonic wave and a metal
ball formed by plating or deposition.
[0070] The protruding connecting terminal 22 is not always formed
of a single metal and may contain a plurality of metal components
such as gold, silver, copper, nickel, indium, palladium, tin and
bismuth, or may be a laminate of layers formed of these metals. The
semiconductor chip 3 having the protruding connecting terminals 22
may be a semiconductor wafer having the protruding connecting
terminals.
[0071] To arrange the protruding connecting terminals 22 of the
semiconductor chip 3 and the board 4 having the wiring patterns 32
formed thereon so as to face each other, the semiconductor chip 3
preferably has an alignment mark in the same surface as that on
which the protruding connecting terminals are formed. The circuit
board to be used as the circuit board 4 having wiring patterns 32
formed thereon may be an ordinary circuit board or a semiconductor
chip.
[0072] In the case of a circuit board, the wiring patterns 32 can
be formed on an insulating board 30, which is formed by
impregnating glass cloth or nonwoven cloth with an epoxy resin and
a resin having a benzotriazine skeleton, and formed on a board
having a build-up layer. The wiring patterns 32 can be also formed
by forming a metal layer such as copper on the surface of an
insulating board 30 formed of, e.g., polyimide, glass or ceramics
and etching away an unnecessary portion of the metal layer.
Alternatively, the wiring patterns can be formed by plating or
depositing a metal on the surface of the insulating board 30.
[0073] The wiring patterns 32 are not always formed of a single
metal and may contain a plurality of metal components such as gold,
silver, copper, nickel, indium, palladium, tin and bismuth, or may
be a laminate of layers of these metals. Furthermore, in the case
where the board is a semiconductor chip, in which the wiring
patterns 32 are usually formed of aluminum, a metal layer of gold,
silver, copper, nickel, indium, palladium, tin and bismuth may be
formed on the surface.
[0074] The state of a semiconductor chip where a circuit-member
connecting adhesive is bonded on the surface having protruding
connecting terminals can be obtained by forming a laminate by
stacking a semiconductor wafer (before processed into chips) having
protruding connecting terminals, the circuit-member connecting
adhesive provided on the surface of the semiconductor wafer having
protruding connecting terminals, and a dicing tape whose sticky
layer is allowed to face the circuit-member connecting adhesive,
sequentially in this order; and cutting the laminate into pieces by
dicing; and removing the discrete semiconductor chips attached with
the circuit-member connecting adhesive from the dicing tape.
Alternatively, the state of a semiconductor chip where a
circuit-member connecting adhesive is bonded on the surface having
protruding connecting terminals can be also obtained by forming a
laminate by providing a circuit-member connecting adhesive on the
connecting terminal surface of a semiconductor wafer (before
processed into chips) having protruding connecting terminals and
providing a dicing tape such that a sticky layer thereof faces the
surface of the semiconductor wafer having no circuit-member
connecting adhesive; and cutting the laminate into pieces by
dicing; and removing the discrete semiconductor chips attached with
the circuit-member connecting adhesive from the dicing tape.
[0075] As the dicing tape having a sticky material applied to a
base tape, a commercially available dicing tape can be used. As a
radiation responsive dicing tape, whose stickiness decreases with
UV irradiation since the sticky layer gradually hardened, thereby
facilitating peel-off of a material laminated on the sticky
surface, a commercially available one can be used.
[0076] The circuit-member connecting adhesive preferably has the
feature that an alignment mark formed on the circuit surface of the
chip can be recognized through the circuit-member connecting
adhesive, which is bonded on the surface of a semiconductor chip
having the protruding connecting terminals. The alignment mark can
be recognized by a chip-recognition unit integrated in an ordinary
flip-chip bonder.
[0077] The recognition unit is generally constituted of a halogen
light source having a halogen lamp, a light guide, an irradiation
apparatus and a CCD camera. The image is taken by the CCD camera,
compared to the image pattern for use in alignment, which has been
previously stored in the image processing unit, and determined
whether both are consistent with each other. In this way, an
alignment operation is performed.
[0078] The expression "an alignment mark can be recognized" herein
means that the image of an alignment mark taken by the
chip-recognition unit of the flip-chip bonder has good consistency
with the image of the alignment mark stored therein and thus an
alignment operation can be performed.
[0079] For example, when flip-chip bonder-CB-1050 (trade name,
manufactured by Athlete FA Corporation) is used, a laminate, which
has a circuit-member connecting adhesive bonded on the surface
having protruding connecting terminals, is adsorbed by an
adsorption nozzle of the flip-chip bonder at the opposite surface
(having the protruding connecting terminals), and thereafter, a
recognition mark formed on the semiconductor chip surface is
photographed through the adhesive layer by a recognition unit
integrated in the apparatus. In the case where the recognition mark
photographed is consistent with the recognition mark of the
semiconductor chip previously taken in the image processing
apparatus, determining that alignment can be performed, the
adhesive is treated as a recognizable circuit-member connecting
adhesive. In contrast, in the case of determining that alignment
cannot be performed, the adhesive is treated as a non-recognizable
circuit-member connecting adhesive. In this manner, the adhesives
can be selected.
[0080] The circuit-member connecting adhesive in a non-hardened
state preferably has a parallel transmittance of 15 to 100%, more
preferably 18 to 100% and further preferably 25 to 100%. When the
parallel transmittance is less than 15%, a recognition mark cannot
be recognized by the flip-chip bonder, with the result that
alignment operation may not be performed.
[0081] The parallel transmittance can be measured by a turbidimeter
NDH2000 (trade name, manufactured by Nippon Denshoku Industries
Co., Ltd) based on integrating-sphere photoelectric photometry. To
explain more specifically, a 50 .mu.m-thick PET film manufactured
by Teijin Dupont Films (Purex, transmittance of whole light beams:
90.45, haze: 4.47) is used as a reference substance. After
correction is made, a circuit-member connecting adhesive is applied
to a PET base to a thickness of 25 .mu.m and subjected to
measurement. From the measurement results, turbidity, whole light
beam transmittance, diffusion transmittance and parallel
transmittance can be obtained.
[0082] The visible-light transmittance can be measured by a U-3310
type spectrophotometer (trade name, manufactured by Hitachi Ltd.).
To explain more specifically, a 50 .mu.m-thick PET film
manufactured by Teijin Dupont Films (Purex, 555 nm, transmittance:
86.03%) is used as a reference substance. After baseline correction
measurement is made, a circuit-member connecting adhesive is
applied to a PET base to a thickness of 25 .mu.m. Then, a
transmittance of visible light within the range of 400 nm to 800 nm
can be measured. Since the relative intensity of a halogen light
source used in the flip-chip bonder to that of the light guide is
the strongest in the range of a wavelength of 550 nm to 600 nm,
transmittance can be compared based on the transmittance at 555 nm
in the present invention.
[0083] The circuit-member connecting adhesive preferably has a
reactivity (measured by DSC after heated at 180.degree. C. for 20
seconds) is preferably of 80% or more, more preferably 84% or more,
and further preferably 86% or more. Note that the reactivity can be
measured, for example, by the following method. First, 2 to 10 mg
of the circuit-member connecting adhesive before a reaction is
weighed in an aluminum measurement container. Calorific value of
the adhesive is measured by DSC while raising a temperature at a
rate of 20.degree. C./min from 30 to 300.degree. C. to obtain an
initial calorific value. Then, the circuit-member connecting
adhesive is heated at 180.degree. C. for 20 seconds by use of a
heating head of a thermocompression bonding apparatus to obtain a
heated circuit-member connecting adhesive. Then, 2 to 10 mg of the
heated circuit-member connecting adhesive is taken and colorific
value is measured by DSC in the same conditions as above to obtain
a calorific value after heating. Based on the calorific values thus
obtained, a reactivity (%) is calculated in accordance with the
following formula:
(Initial calorific value-calorific value after heating)/(initial
calorific value).times.100.
[0084] The circuit-member connecting adhesive preferably has an
adhesive force of 10 N/m or less to a UV-irradiated dicing tape and
an adhesive force of 70 N/m or more to a semiconductor wafer. When
the adhesive force to a dicing tape after UV irradiation exceeds 10
N/m, the semiconductor chips may break and the adhesive layer may
deform in a process where diced and separated semiconductor chips
attached with the circuit-member connecting adhesive are peeled off
from the dicing tape. On the other hand, when the adhesive force to
a semiconductor wafer is less than 70 N/m, chips and the adhesive
may separate at the interface by the effect of shock and hydraulic
pressure given by rotary cleavage of a blade in a dicing
process.
[0085] The adhesive force between the circuit-member connecting
adhesive and the UV irradiated dicing tape can be measured, for
example, by the following method. First, the circuit-member
connecting adhesive is laminated on a wafer by a laminator set at a
heating temperature of 80.degree. C. The dicing tape before UV
irradiation is laminated at 40.degree. C. such that the sticky
surface of the tape is brought into contact with the circuit-member
connecting adhesive. Thereafter, UV rays (about 300 mJ at 15 mW)
are applied to the dicing tape. Subsequently, slits are made in the
UV irradiated dicing tape at width of 10 mm to prepare strips for
tensile strength measurement.
[0086] Subsequently, the wafer is clamped on a stage and one end of
the dicing-tape strip is fixed to a pulling jig of a tensile force
measurement machine. The UV irradiated dicing tape and the
circuit-member connecting adhesive are peeled off. In this manner,
a 90.degree. peel test is performed. Based on the measurement, the
adhesive force between the UV irradiated dicing tape and the
circuit-member connecting adhesive can be measured.
[0087] The adhesive force between the circuit-member connecting
adhesive and the semiconductor wafer can be measured, for example,
by the following method. First, the circuit-member connecting
adhesive is laminated on the wafer by a laminator set at a heating
temperature of 80.degree. C. Thereafter, Kapton (registered trade
mark) tape (manufactured by Nitto Denko Corporation, 10 mm in
width, 25 .mu.m in thickness) is bonded to the circuit-member
connecting adhesive so as to face the sticky surface thereof and
made tight sufficiently. After that, slits are made in the
circuit-member connecting adhesive bonded to Kapton (registered
trade mark) tape at width of 10 mm.
[0088] One end of the resultant laminate of the circuit-member
connecting adhesive and Kapton (registered trade mark) tape is
peeled off from the wafer and fixed to a pulling jig of a tensile
force measurement machine. The wafer is clamped on a stage and one
end of a strip is pulled up to peel off the circuit-member
connecting adhesive from the wafer. In this manner, a 90.degree.
peel test is performed. Based on the measurement, the adhesive
force between the circuit-member connecting adhesive and the wafer
can be measured.
[0089] After bonding, the circuit-member connecting adhesive, in
order to suppress temperature change and expansion due to heating
and moisture adsorption, etc., after connecting between the
semiconductor chip and a circuit board, preferably has a linear
expansion coefficient (after hardening, measured at 40.degree. C.
to 100.degree. C.) of 70.times.10.sup.-6/.degree. C. or less, more
preferably 60.times.10.sup.-6/.degree. C. or less, further
preferably 55.times.10.sup.-6/.degree. C. or less, and particularly
preferably 50.times.10.sup.-6/.degree. C. or less. When the linear
expansion coefficient (after hardening) exceeds
70.times.10.sup.-6/.degree. C., the electric contact between
connecting terminals of a semiconductor chip and wiring of a
circuit board may not be maintained due to temperature change and
expansion by heating and moisture adsorption after mounting.
[0090] The circuit-member connecting adhesive contains an adhesive
resin composition and composite oxide particles. The adhesive resin
composition preferably has a parallel transmittance of 15% or more,
more preferably 30% or more, and further preferably 40% or more.
The case where the parallel transmittance is 40% or more is
preferred since a predetermined transmittance can be satisfactorily
obtained even if the content of composite oxide particles is high.
When the parallel transmittance of the adhesive resin composition
is less than 15% or less, a recognition mark cannot be recognized
by a flip-chip bonder even if composite oxide particles are not
added. As a result, an alignment operation may not be
performed.
[0091] The composite oxide particles to be used in the present
invention preferably have a refractive index of 1.5 to 1.7 and more
preferably 1.53 to 1.65. If the refractive index of the composite
oxide particles is less than 1.5, when the particles are blended in
the adhesive resin composition, the refractive index difference
from the resin composition becomes large. As a result, light is
scattered when it passes through the circuit-member connecting
adhesive and alignment may not be performed. On the other hand, if
the refractive index exceeds 1.7, the refractive index difference
from the resin increases, with the result that light is scattered
and alignment may not be performed. The refractive index can be
measured by Abbe refractometer using sodium D-line (589 nm) as a
light source.
[0092] The composite oxide particles to be used in the present
invention preferably have an average particle size of 15 .mu.m or
less and a maximum particle size of 40 .mu.m or less, more
preferably have an average particle size of 5 .mu.m or less, and
further preferably have an average particle size of 3 .mu.m or
less. The composite oxide particles are particles having an average
particle size of 3 .mu.m or less and a maximum particle size of 20
.mu.m or less, and furthermore, particles particularly preferably
having an average particle size of 3 .mu.m or less and a maximum
particle size of 5 .mu.m or less. The case where the average
particle size exceeds 15 .mu.m is not preferred. This is because
composite oxide particles enter between bumps (connecting
terminals) of a chip and electrodes of a circuit board (a board
having wiring patterns formed thereon). In particular, when
mounting is performed under low pressure and when bumps are made of
a hard substance such as nickel, embedding is not performed and
electric contact is suppressed. In contrast, when the maximum
particle size exceeds 40 .mu.m, the particle size may exceed the
gap between the chip and the board. Consequently, the particles may
damage the circuit of the chip or the circuit of the board when
pressure is applied during a mounting process.
[0093] The composite oxide particles to be used in the present
invention preferably have a specific gravity of 4 or less, more
preferably 2 to 4, and further preferably 2 to 3.2. If the specific
gravity exceeds 4, when the particles are added to a varnish of an
adhesive resin composition, they may precipitate in the vanish due
to a large difference of specific gravity. As a result, the
circuit-member connecting adhesive having composite oxide particles
uniformly dispersed therein may not be obtained.
[0094] Furthermore, the composite oxide particles to be used in the
present invention preferably have a refractive-index difference
with the adhesive resin composition within .+-.0.06, more
preferably within .+-.0.02, and further preferably within .+-.0.01.
When the refractive-index difference exceeds .+-.0.06, the
transmittance of the adhesive resin composition decreases by adding
the particles. As a result, an alignment mark formed on the circuit
surface of a chip cannot be recognized in some cases through the
circuit-member connecting adhesive bonded on the surface of a
semiconductor chip having the protruding connecting terminals
thereon.
[0095] As such a composite oxide, one having a refractive index of
1.5 to 1.7 and a refractive-index difference with an adhesive resin
composition within .+-.0.06 is particularly preferred. Examples of
such a composite oxide include oxides containing metal elements
such as zinc, aluminum, antimony, ytterbium, yttrium, indium,
erbium, osmium, cadmium, calcium, potassium, silver, chrome,
cobalt, samarium, dysprosium, zirconium, tin, cerium, tungsten,
strontium, tantalum, titanium, iron, copper, sodium, niobium,
nickel, vanadium, hafnium, palladium, barium, bismuth,
praseodymium, beryllium, magnesium, manganese, molybdenum,
europium, lanthanum, phosphorus, lutetium, ruthenium, rhodium and
boron. They may be used in combination.
[0096] The composite oxide is preferably a compound containing not
less than two types of metals as a raw material which has a
different structure from an oxide structure formed of each of the
raw material metals. Particularly preferably, the composite oxide
particles are formed of at least one type of metal element selected
from aluminum, magnesium or titanium and an oxide compound
containing at least two types of elements except the aforementioned
elements. As such a composite oxide, aluminum borate, cordierite,
forsterite and mullite, etc may be mentioned. The composite oxide
may be an aluminum composite oxide or a silicone composite oxide
substituted with a metal element such as magnesium. Note that, in
the present invention, a metalloid element (half-metal) such as
silicon and boron is treated as a metal for forming a composite
oxide.
[0097] The linear expansion coefficient of the composite oxide
particles is preferably 7.times.10.sup.-6/.degree. C. in the
temperature range of 0 to 700.degree. C. or less, and more
preferably 3.times.10.sup.-6/.degree. C. or less. When the linear
expansion coefficient exceeds 7.times.10.sup.-6/.degree. C., a
large amount of composite oxide particles must be added in order to
reduce the linear expansion coefficient of the circuit-member
connecting adhesive.
[0098] As the composite oxide particles, cordierite is further
preferable since fine adjustment of the refractive index can be
made and the linear expansion coefficient is low. Cordierite is a
compound represented by a general composition of
MgO/Al.sub.2O.sub.3/SiO.sub.2 and has a refractive index of 1.54.
The ratio of MgO/Al.sub.2O.sub.3/SiO.sub.2 is 2/2/5. Fine
adjustment of the refractive index can be made by slightly changing
the ratio. The linear expansion coefficient of a crystallized
compound is 2.times.10.sup.-6/.degree. C. or less. The composite
oxide particles contained in the circuit-member connecting adhesive
preferably contain cordierite particles. The composite oxide
particles may contain cordierite particles alone or may contain
composite oxide particles other than cordierite particles. In the
latter case, the content of the cordierite particles is preferably
50 wt % or more based on the total amount of the composite oxide
particles, more preferably 70 wt % or more, and further preferably
90 wt % or more.
[0099] In the circuit-member connecting adhesive, the content of
the composite oxide particles is preferably 25 to 200 parts by
weight relative to 100 parts by weight of a resin composition. The
content is more preferably 25 to 150 parts by weight, further
preferably 50 to 150 parts by weight, and particularly preferably
75 to 125 parts by weight. When the content of the composite oxide
particles is less than 25 parts by weight, the linear expansion
coefficient of the circuit-member connecting adhesive may increase
and the elastic modulus may decrease. In such a case, connection
reliability between a semiconductor chip and a board after
pressure-bonding decreases. On the other hand, when the content of
the composite oxide particles exceeds 200 parts by weight, the melt
viscosity of the circuit-member connecting adhesive increases, with
the result that sufficient contact between protruding electrodes of
a semiconductor to the circuit of a board may become difficult.
[0100] The circuit-member connecting adhesive contains a resin
composition and composite oxide particles dispersed in the resin
composition. The resin composition contains a thermoplastic resin,
a crosslinkable resin and a hardening agent capable of forming a
crosslink structure of this resin. The resin composition or
circuit-member connecting adhesive may contain other additives (a
filler, a plasticizer, a coloring agent, a crosslinking auxiliary,
etc.) as long as the effect of the present invention is not
inhibited. Note that the resin composition may consist only of a
thermoplastic resin, a crosslinkable resin and a hardening agent
capable of forming a crosslink structure of this resin. The
circuit-member connecting adhesive may consist only of the resin
composition and composite oxide particles dispersed in the resin
composition.
[0101] As the thermoplastic resin contained in the resin
composition, mention may be made of a polyolefin (such as
polyethylene, polypropylene), an ethylene copolymer (such as an
ethylene-a olefin copolymer, an ethylene-vinyl acetate copolymer,
an ethylene-(meth)acrylate copolymer), a styrene block copolymer,
an acrylic polymer (which refers to a polymer of monomers having a
(meth)acryloyl group), an acrylic copolymer (which refers to a
copolymer containing a monomer having a (meth)acryloyl group as a
co-monomer) and a phenoxy resin. An acrylic polymer and acrylic
copolymer or a phenoxy resin is preferred. The thermoplastic resin
preferably has a weight average molecular weight of 1 million or
less, more preferably 0.5 millions or less, and further preferably
0.3 millions or less. Furthermore, the Tg of the thermoplastic
resin is preferably 40.degree. C. or less, and more preferably
35.degree. C. or less.
[0102] The crosslinkable resin contained in the resin composition
is a resin (three-dimensional crosslinking resin) forming a three
dimensional crosslink by the action of the hardening agent used in
combination with energy application such as heat/light irradiation,
and preferably a resin having a functional group reactive to the
hardening agent with application of heat and light. As such a
crosslinkable resin, mention may be made of an epoxy resin, a
bismaleimide resin, a triazine resin, a polyimide resin, a
polyamide resin, a cyanoacrylate resin, a phenolic resin, an
unsaturated polyester resin, a melamine resin, a urea resin, a
polyurethane resin, a polyisocyanate resin, a furan resin, a
resorcinol resin, a xylene resin, a benzoguanamine resin, a diallyl
phthalate resin, a silicone resin, a polyvinylbutyral resin, a
siloxane-modified epoxy resin, a siloxane-modified polyamide-imide
resin and an acrylate resin, etc. They may be used singly or as a
mixture of two types or more.
[0103] The hardening agent which acts on such a crosslinkable resin
to form a crosslinking structure can be determined in accordance
with the reactivity (e.g., type of a functional group) of the
crosslinkable resin. As the hardening agent, mention may be made of
hardening agents of a phenolic base, imidazole base, hydrazide
base, thiol base, benzoxazine, a boron trifluoride-amine complex, a
sulfonium salt, amine-imide, a polyamine salt, dicyandiamide and an
organic peroxide base. These hardening agents may be microcapsules
having a coat of a polymer substance such as a polyurethane polymer
and a polyester polymer to extend its work life.
[0104] The thermoplastic resin is preferably a co-polymerizable
resin having a weight average molecular weight of 1 million or less
(preferably 0.5 millions or less, and further preferably 0.3
millions or less) and a Tg of 40.degree. C. or less (preferably
35.degree. C. or less) and containing at least one functional group
reactive to a crosslinkable resin in a side chain. As a hardening
agent, a microencapsulated hardening agent is preferred. It is
particularly preferred that such a copolymerizable resin may be
used in combination with the microencapsulated hardening agent.
Note that Tg (glass transition temperature) can be measured by the
DSC method specified by HS K7121 "plastic transition temperature
measurement method".
[0105] As the copolymerizable resin having a weight average
molecular weight of 1 million or less and a Tg of 40.degree. C. or
less and containing at least one functional group reactive to a
crosslinkable resin in a side chain, it is preferred to use acrylic
copolymers containing an epoxy group, a carboxyl group and a
hydroxyl group in a side chain as the functional group reactive to
a crosslinkable resin. Particularly, an epoxy group-containing
acrylic copolymer is preferred, which is obtained by using e.g.,
glycidyl acrylate or glycidyl methacrylate as a raw material for an
acrylic copolymer.
[0106] As a raw material for use in copolymerization of the
copolymerizable resin, use may be made of hydroxy
alkyl(meth)acrylates such as hydroxyethyl(meth)acrylate,
hydroxypropyl(meth)acrylate and hydroxybutyl(meth)acrylate;
(meth)acrylic esters such as methyl methacrylate,
butyl(meth)acrylate, 2-ethylhexyl(meth)acrylate,
cyclohexyl(meth)acrylate, furfuryl(meth)acrylate,
lauryl(meth)acrylate, stearyl(meth)acrylate,
trimethylcyclohexyl(meth)acrylate, tricyclodecyl(meth)acrylate, and
tetracyclododecyl-3-acrylate; styrene, vinyl toluene, polypropylene
glycol monomethacrylate, hydroxyethyl acrylate, acrylonitrile,
benzyl methacrylate, cyclohexylmaleimide and the like.
[0107] The microencapsulated hardening agent is referred to one
containing a hardening agent serving as a core, which is
substantially coated with a film such as a thin film made of a
polymer substance such as polyurethane, polystyrene, gelatin or
polyisocyanate; an inorganic substance such as calcium silicate or
zeolite; and a metal such as nickel or copper. The average particle
size of the microencapsulated hardening agent is preferably 10
.mu.m or less, and more preferably 5 .mu.m or less.
[0108] The resin composition may contain a microencapsulated
hardening agent or a non-microencapsulated hardening agent. The
resin composition may also contain a coupling agent in order to
increase adhesion intensity and a thermoplastic resin such as
polyester, polyurethane, polyvinyl butyral, a polyarylate,
polymethyl methacrylate, acrylic rubber, polystyrene, phenoxy
resin, NBR, SBR, polyimide and a silicone-modified resin (acrylic
silicone, epoxy silicone, polyimide silicone) to contribute to film
formability. Furthermore, to modify the surface of composite oxide
particles, silicone oil, polysiloxane, a silicone oligomer and a
coupling agent may be contained.
[0109] The circuit-member connecting adhesive can be an anisotropic
conductive adhesive which is prepared by adding conductive
particles having a particle size of 3 to 5 .mu.m and coated with an
organic polymer compound and/or metal conductive particles. As the
conductive particles before coated with an organic polymer
compound, metal particles of Au, Ag, Ni, Cu and solder and carbon
particles may be used. To obtain a sufficient pot life, the surface
of the particles may not be made of a transition metal such as Ni
or Cu and preferably made of a precious metal such as Au, Ag or
platinum, and more preferably Au.
[0110] Furthermore, the surface of a transition metal such as Ni
may be coated with a precious metal such as Au. Moreover,
particles, which are formed by coating a non-conductive glass,
ceramic and plastic, etc. with a conductive layer as mentioned
above and adding a precious metal as the outermost layer, and
thermofusion metal particles are preferred. This is because they
deform when heat or pressure is applied and cancel out variation in
height of electrodes to increase the contact area with the
electrodes when connected, thereby improving reliability. The
thickness of the precious-metal coating layer is preferably 100
angstroms or more in order to obtain good resistance.
[0111] However, when a precious-metal layer is formed on a
transition metal such as Ni, if there is a defect of the precious
metal layer; i.e., a defect of the precious metal layer produced in
mixing and dispersing conductive particles, an oxidation-reduction
reaction occurs. Consequently, free radicals are generated and
decrease storageability. Therefore, the thickness of the precious
metal layer is preferred to be 300 angstroms or more. As the
thickness increases, the aforementioned effects come to be
saturated. For the reason, the thickness is, but not particularly
limited to, desirably at most 1 .mu.m. The surface of the
conductive particles is coated with an organic polymer compound as
needed.
[0112] The organic polymer compound to be used for coating is
preferably water soluble because coating operation can be easily
performed. As the water soluble polymer, mention may be made of
polysaccharides such as alginic acid, pectic acid,
carboxymethylcellulose, agar, curdlan and pullulan; polycarboxylic
acids such as polyaspartic acid, polyglutaminic acid, polylysine,
polymalic acid, polymethacrylic acid, ammonium polymethacrylate,
sodium polymethacrylate, polyamic acid, polymaleic acid,
polyitaconic acid, polyfumaric acid, poly(p-styrene carboxylic
acid), polyacrylic acid, polyacrylamide, methyl polyacrylate, ethyl
polyacrylate, ammonium polyacrylate, sodium polyacrylate, polyamic
acid, ammonium polyamidate, sodium polyamidate and polyglyoxylic
acid; polycarboxylic ester and salts thereof; and vinyl monomers
such as polyvinyl alcohol, polyvinyl pyrrolidone and polyacrolein.
These compounds may be used singly or in combination of two types
or more.
[0113] The thickness of the coating is preferably 1.mu.m or less.
Since conductive particles are electrically connected with
connecting terminals by eliminating the coating. Therefore, the
part of the coating in contact with the connecting terminals must
be eliminated in a heating and pressurizing process. The content of
the conductive particles may be varied depending upon the use
within the range of 0.1 to 30 parts by volume relative to 100 parts
by volume of the adhesive resin component. To prevent a problem
such as short circuit to an adjacent circuit by excessive
conductive particles, the content of the conductive particles is
more preferably 0.1 to 10 parts by volume.
[0114] A laminate, which is formed of a semiconductor wafer having
protruding connecting terminals, the circuit-member connecting
adhesive (or circuit-member connecting anisotropic conductive
adhesive) and a dicing tape that is to be hardened by UV
irradiation, can be also obtained by laminating the semiconductor
wafer and the circuit-member connecting adhesive by an apparatus
having a heating mechanism and a pressurizing roller or an
apparatus having a heating mechanism or a vacuum press mechanism
and thereafter, further laminating with the dicing tape by an
apparatus such as a wafer mounter.
[0115] Furthermore, the laminate, which is formed of a
semiconductor wafer having protruding connecting terminals, the
circuit-member connecting adhesive (or circuit-member connecting
anisotropic conductive adhesive) and a dicing tape that is to be
hardened by UV irradiation, can be also obtained by laminating the
circuit-member connecting adhesive and the dicing tape to prepare a
laminate, that is then laminated on the semiconductor wafer by a
wafer mounter having a heating mechanism and a pressurizing roller
or a wafer mounter having a heating mechanism or a vacuum press
mechanism.
[0116] Laminating of a semiconductor wafer and a circuit-member
connecting adhesive or laminating a laminate of a semiconductor
wafer and a circuit-member connecting adhesive is preferably
performed at a temperature at which the circuit-member connecting
adhesive is softened, for example, preferably performed while
heating to 40 to 80.degree. C., more preferably while heating to 60
to 80.degree. C., further preferably while heating to 70 to
80.degree. C.
[0117] When laminating is performed at less than a softening
temperature of the circuit-member connecting adhesive, the
protruding connecting terminals of a semiconductor wafer are not
sufficiently embedded in the peripheral portion and voids are
involved, which may cause peel-off in a dicing process, distortion
of the circuit-member connecting adhesive during a pick-up process,
invisibility of a recognition mark during an alignment process.
Furthermore, connection reliability may decrease due to the
voids.
[0118] When a laminate, which is formed of a semiconductor wafer, a
circuit-member connecting adhesive and a dicing tape, are diced, a
scribe line can be aligned by use of an IR recognition camera by
recognizing an alignment mark on a circuit pattern of the
semiconductor wafer or an alignment mark for dicing through the
wafer.
[0119] In a laminate, which is formed of a semiconductor wafer, a
circuit-member connecting adhesive and a dicing tape, a step of
cutting the semiconductor wafer and the circuit-member connecting
adhesive can be performed by a dicer usually used. The cutting by
the dicer is performed in accordance with a step generally called
as dicing.
[0120] Dicing may be preferably performed stepwise. In the first
step, a wafer alone is cut. In the second step, the wafer remaining
in the cut groove of the first step and the circuit-member
connecting adhesive are preferably cut until the interface with the
dicing tape or partly within the dicing tape.
[0121] A laminate, which is formed of a semiconductor wafer, a
circuit-member connecting adhesive and a dicing tape, can be diced
by a laser. In the UV irradiation step after dicing, UV irradiation
(about 150 to 300 mJ) can be applied to the dicing tape by a
general light-exposure apparatus or the like at 15 to 30 mW.
[0122] The dicing tape and the adhesive are separated by pushing
the dicing tape toward the semiconductor wafer to obtain diced
(discrete) semiconductor chips attached with an adhesive. This step
can be carried out by an apparatus capable of picking up the chips
from the wafer. The dicing tape is pressed from the opposite
surface of the tape on which semiconductor chips are mounted so as
to extend by pressure. In this way, the circuit-member connecting
adhesive and the UV irradiated dicing tape are peeled off by being
separated at the interface thereof.
[0123] An adsorption step, an alignment step and a
heating/pressurizing step of adhesive chips can be carried out by a
general flip-chip bonder. Alternatively, the adsorption step and
the alignment step are carried out, and the semiconductor chips
aligned are provisionally fixed on a board and the
heating/pressurizing step may be performed by a pressure-bonding
apparatus (exclusively performing pressure-bonding) to make a
connection. Furthermore, connection can be made not only by
applying heat and pressure but also while applying ultrasonic
wave.
EXAMPLES
[0124] The present invention will be more specifically described
below by way of Examples; however, the present invention is not
limited to these Examples.
Example 1
[0125] As a crosslinkable resin, an epoxy resin NC 7000 (trade
name, manufactured by Nippon Kayaku Co., Ltd.): 15 parts by weight,
was used. As a hardening agent reacting with the crosslinkable
resin, phenol-aralkyl resin XLC-LL (trade name, manufactured by
Mitsui Chemicals Inc.): 15 parts by weight, was used. As a
copolymerizable resin having a molecular weight of 1 million or
less and a Tg of 40.degree. C. or less and containing at least one
functional group reactive to the crosslinkable resin in a side
chain, an epoxy group-containing acrylic rubber HTR-860P-3 (trade
name, manufactured by Nagase ChemteX Corporation, the weight
average molecular weight: 0.3 million): 20 parts by weight, was
used. As microencapsulated hardening agent, HX-3941HP (trade name,
manufactured by Asahi Kasei Corporation): 50 parts by weight and a
silane coupling agent SH6040 (trade name, manufactured by Toray Dow
Corning Silicone, Co., Ltd.) were used. The aforementioned
substances were dissolved in a toluene/ethyl acetate solvent
mixture in accordance with the composition listed in Table 1 to
obtain a varnish of an adhesive resin composition.
[0126] Part of the varnish was applied onto a separator film (PET
film) by a roll coater, and the dried in an oven of 70.degree. C.
for 10 minutes to obtain a 25 .mu.m-thick adhesive resin
composition on the separator. The film was placed on a sample stage
of Abbe refractometer (sodium D line). After the separator was
peeled off, a single droplet of matching oil was dropped and a test
piece having a refractive index of 1.74 was placed. Then, a
refractive index was measured. As a result, the refractive index of
the adhesive resin composition was 1.59 (25.degree. C.).
[0127] On the other hand, to the varnish, cordierite particles of 1
.mu.m in average particle size (2MgO.2Al.sub.2O.sub.3.5SiO.sub.2,
specific gravity: 2.4, linear expansion coefficient:
1.5.times.10.sup.-6/.degree. C., refractive index: 1.54), which
were weighed, pulverized and subjected to 5 .mu.m-classification to
remove large particles, were mixed in accordance with the
composition listed in Table 1 and stirred to disperse. Thereafter,
the varnish was applied onto a separator film (PET film) by use of
a roll coater and then dried in an oven of 70.degree. C. for 10
minutes to obtain a 25 .mu.m-thick transparency confirmation film
on the separator. As shown in FIG. 11, an image on the rear side of
the obtained transparency confirmation film was recognized through
the film.
[0128] Aside from the above, to the varnish, cordierite particles
of 1 .mu.m in average particle size
(2MgO.2Al.sub.2O.sub.3.5SiO.sub.2, specific gravity: 2.4, linear
expansion coefficient: 1.5.times.10.sup.-6/.degree. C., refractive
index: 1.54), which were weighed, pulverized and subjected to 5
.mu.m-classification to remove large particles, were mixed in
accordance with the composition listed in Table 1 and stirred to
disperse. Thereafter, the varnish was applied onto a separator film
(PET film) by use of a roll coater and then dried in an oven of
70.degree. C. for 10 minutes to obtain a 20 .mu.m-thick insulating
adhesive layer of a circuit-member connecting adhesive on the
separator.
Examples 2 to 4
[0129] Varnishes of adhesive resin compositions were prepared in
accordance with the compositions listed in Table 1 in the same
manner as in Example 1 and through the same steps as in Example 1,
and thereafter transparency confirmation films were prepared and
simultaneously insulating adhesive layers of circuit-member
connecting adhesives were obtained.
Example 5
[0130] A varnish of adhesive resin composition was prepared in
accordance with the composition listed in Table 1 in the same
manner as in Example 1 and through the same steps as in Example 1.
A transparency confirmation film was prepared through the same
steps as in Example 1 except that aluminum borate
(9Al.sub.2O.sub.3.2B.sub.2O.sub.3, manufactured by Shikoku
Chemicals Corporation, specific gravity: 3.0, linear expansion
coefficient: 2.6.times..sup.-6/.degree. C., refractive index: 1.62)
was used, and simultaneously an insulating adhesive layer of a
circuit-member connecting adhesive.
Example 6
[0131] A varnish of adhesive resin composition containing
cordierite particles was prepared in accordance with the
composition listed in Table 1 in the same manner as in Example 1
and through the same steps as in Example 1 to obtain a 45
.mu.m-thick circuit-member connecting adhesive on a separator
film.
[0132] Subsequently, a chip (10 mm square, 280 .mu.m in thickness)
with 184 gold wire bumps (leveled, 30 .mu.m in height) was placed
on a stage of a provisional pressure-bonding apparatus with the
bump-surface facing up. The circuit-member connecting adhesive
attached with a separator were cut into 12 mm-square pieces and
placed over the chip such that the adhesive faces the bump-surface.
Furthermore, a heat-conductive cover film made of silicon was
placed thereon and bonded to the chip at 80.degree. C. and 1
MPa.
[0133] After adhesion, the resin running off the outer edge of the
chip was cut. The separator was peeled off from the adhesive to
obtain a chip with the adhesive. When the chip with the adhesive
was observed by a recognition camera of a flip-chip bonder, an
alignment mark on the circuit surface of the chip was successfully
recognized.
[0134] Alignment with a Ni/Au plated Cu printed circuit board was
performed. Subsequently, heating and pressurization were performed
at 180.degree. C. and 0.98 N/bump for 20 seconds to obtain a
semiconductor device. The connection resistance of the obtained
semiconductor device (176 bump connecting daisy chain) was
8.6.OMEGA.. It was confirmed that good connection state was
obtained.
[0135] Furthermore, the semiconductor device was allowed to stand
alone in a vessel set at 30.degree. C. and a relative humidity of
60% for 192 hours. Thereafter, an IR reflow treatment (maximum
temperature: 265.degree. C.) was repeated three times. No peel-off
of chips and conduction failure were observed.
[0136] After the IR reflow treatment, the semiconductor device was
further allowed to stand alone in a temperature cycle tester
(-55.degree. C. for 30 minutes, room temperature for 5 minutes and
125.degree. C. for 30 minutes). Connection resistance was measured
in the vessel. It was confirmed that no conduction failure occurs
after 600 cycles.
Example 7
[0137] As a crosslinkable resin, epoxy resin EP1032H60 (trade name,
manufactured by Japan Epoxy Resins Co., Ltd.) and a phenoxy resin
YP50S (trade name, manufactured by Tohto Kasei Co., Ltd.,) having a
weight average molecular weight of 70000 were used. As a
microencapsulated hardening agent, HX-3941HP (trade name,
manufactured by Asahi Kasei Corporation) and a silane coupling
agent SH6040 (trade name, manufactured by Toray Dow Corning
Silicone, Co., Ltd.) were used. These substances were mixed in
accordance with the composition listed in Table 1 and dissolved in
a toluene/ethyl acetate solvent mixture to obtain a varnish of an
adhesive resin composition.
[0138] To the varnish, 50 parts by weight of cordierite particles
of 1 .mu.m in average particle size
(2MgO.2Al.sub.2O.sub.3.5SiO.sub.2, specific gravity: 2.4, linear
expansion coefficient: 1.5.times.10.sup.-6/.degree. C., refractive
index: 1.54), which were pulverized and subjected to 5
.mu.m-classification to remove large particles, were mixed and
stirred to disperse. Thereafter, the varnish was applied onto a
separator film (PET film) by use of a roll coater, and then dried
in an oven of 70.degree. C. for 10 minutes to obtain a 45
.mu.m-thick circuit-member connecting adhesive.
[0139] Subsequently, the adhesive was bonded to a chip attached
with gold wire bumps in the same manner as in Example 6 and then
connected to Au/Ni plated Cu printed circuit board to obtain a
semiconductor device. The connection resistance of the obtained
semiconductor device (176 bump connecting daisy chain) was
8.6.OMEGA.. It was confirmed that good connection state was
obtained.
[0140] Furthermore, the semiconductor device was allowed to stand
alone in a vessel set at 30.degree. C. and a relative humidity of
60% for 192 hours. Thereafter, an IR reflow treatment (maximum
temperature: 265.degree. C.) was repeated three times. No peel-off
of chips and conduction failure were observed.
[0141] After the IR reflow treatment, the semiconductor was allowed
to stand alone in a temperature cycle tester (-55.degree. C. for 30
minutes, room temperature for 5 minutes and 125.degree. C. for 30
minutes). Connection resistance was measured in the vessel. It was
confirmed that no conduction failure occurs after 600 cycles.
TABLE-US-00001 TABLE 1 Trade name or Example material name 1 2 3 4
5 6 7 NC7000 15 15 15 15 15 15 -- EP1032H60 -- -- -- -- -- -- 20
XLC-LL 15 15 15 15 15 15 -- HTR-860P-3 20 20 20 20 20 20 -- YP50S
-- -- -- -- -- -- 35 HX-3941HP 50 50 50 50 50 50 45 SH6040 1 1 1 1
1 1 1 Cordierite 100 75 50 25 -- 50 50 Aluminum borate -- -- -- --
50 -- -- (Unit: part by weight)
Example 8
[0142] Transparency confirmation film having a composition listed
in Table 2 was prepared in the same procedures as mentioned above
except that conductive particles of 3 .mu.m in average particle
size, which were formed by providing a 0.2 .mu.m-thick nickel layer
on the surface of particles having a polystyrene core and providing
a 0.04 .mu.m thick gold layer outside the nickel layer, were
further mixed with the insulating adhesive layer obtained in
Example 1, and a 5 .mu.m-thick particle layer for a circuit-member
connecting adhesive was obtained on the separator. The insulating
adhesive layer and the particle layer were bonded by a laminator to
obtain a 25 .mu.m-thick circuit-member connecting anisotropic
conductive adhesive.
Examples 9 to 11
[0143] The same steps as in Example 8 were repeated except that, to
the insulating adhesive layers obtained in Examples 2 to 4, further
a 0.2 .mu.m-thick nickel layer was provided on the surface of
particles having a polystyrene core. As a result, a 25 .mu.m-thick
circuit-member connecting anisotropic conductive adhesives were
obtained.
Example 12
[0144] The same steps as in Example 8 were repeated except that, to
the insulating adhesive layers obtained in Example 5, a 0.2
.mu.m-thick nickel layer was provided on the surface of particles
having a polystyrene core. As a result, a 25 .mu.m-thick
circuit-member connecting anisotropic conductive adhesive was
obtained.
TABLE-US-00002 TABLE 2 Trade name or Example material name 8 9 10
11 12 NC7000 15 15 15 15 15 EP1032H60 -- -- -- -- -- XLC-LL 15 15
15 15 15 HTR-860P-3 20 20 20 20 20 YP50S -- -- -- -- -- HX-3941HP
50 50 50 50 50 SH6040 1 1 1 1 1 Cordierite 100 75 50 25 -- Aluminum
borate -- -- -- -- 50 Conductive 5 vol % 5 vol % 5 vol % 5 vol % 5
vol % particles (Unit: part by weight)
Comparative Example 1
[0145] As a crosslinkable resin, an epoxy resin NC7000 (trade name,
manufactured by Nippon Kayaku Co., Ltd.) was used. As a hardening
agent reacting with the crosslinkable resin, phenol-aralkyl resin
XLC-LL (trade name, manufactured by Mitsui Chemicals Inc.) was
used. As a copolymerizable resin having a molecular weight of 1
million or less and a Tg of 40.degree. C. or less and containing at
least one functional group reactive to the crosslinkable resin in a
side chain, an epoxy-group containing acrylic rubber HTR-860-3
(trade name, manufactured by Nagase ChemteX Corporation, weight
average molecular weight: 0.3 million) was used. As
microencapsulated hardening agent, HX-3941HP (trade name,
manufactured by Asahi Kasei Corporation) and a silane coupling
agent SH6040 (trade name, manufactured by Toray Dow Corning
Silicone, Co., Ltd.) were used. The aforementioned substances were
dissolved in a toluene/ethyl acetate solvent mixture in accordance
with the composition listed in Table 3 to obtain a varnish of an
adhesive resin composition.
[0146] To the varnish, silica particles SE2050 of 0.5 .mu.m in
average particle size (trade name, manufactured by Admatechs Co.,
Ltd., specific gravity: 2.22, linear expansion coefficient:
5.times.10.sup.-7/.degree. C., refractive index: 1.46), which were
subjected to 5 .mu.m-classification to remove large particles, were
mixed in accordance with the composition listed in Table 3 and
stirred to disperse. Thereafter, the varnish was applied onto a
separator film (PET film) by use of a roll coater and then dried in
an oven of 70.degree. C. for 10 minutes to obtain a 25 .mu.m-thick
transparency confirmation film on the separator.
[0147] As shown in FIG. 10, it was difficult to recognize an image
on the rear side of the obtained transparency confirmation film
through the film.
[0148] Subsequently, the varnish was weighed and silica particles
SE2050 having an average particle size of 0.5 .mu.m were mixed in
accordance with the composition listed in Table 3 and stirred to
disperse. Thereafter, the varnish was applied onto a separator film
(PET film) by use of a roll coater and then dried in an oven of
70.degree. C. for 10 minutes to obtain a 20 .mu.m-thick insulating
adhesive layer of a circuit-member connecting adhesive on a
separator.
Comparative Example 2
[0149] A varnish for an adhesive resin composition was prepared in
accordance with the composition listed in Table 3 in the same
manner as in Comparative Example 1 and through the same steps as in
Comparative Example 1. Thereafter, a transparency confirmation film
was prepared and simultaneously an insulating adhesive layer of a
circuit-member connecting adhesive was obtained.
Comparative Example 3
[0150] A varnish for an adhesive resin composition was prepared in
accordance with the composition listed in Table 3 in the same
manner as in Comparative Examples 1 and 2 and through the same
steps as in Comparative Example 1. Thereafter, the varnish was
applied onto a separator film (PET film) by use of a roll coater
and then dried in an oven of 70.degree. C. for 10 minutes to obtain
a 20 .mu.m-thick insulating adhesive layer of a circuit-member
connecting adhesive on the separator.
Comparative Example 4
[0151] As a crosslinkable resin, an epoxy resin NC7000 (trade name,
manufactured by Nippon Kayaku Co., Ltd.) was used. As a
copolymerizable resin having a molecular weight of 1 million or
less and a Tg of 40.degree. C. or less and containing at least one
functional group reactive to the crosslinkable resin in a side
chain, an epoxy-group containing acrylic rubber HTR-860P-3 (trade
name, manufactured by Nagase ChemteX Corporation, weight average
molecular weight: 0.3 million) was used. As a hardening agent, 2PHZ
(trade name, manufactured by Shikoku Chemicals Corporation), a
silane coupling agent SH6062 (trade name, manufactured by Dow
Corning Toray, Co., Ltd.), A1160 (trade name, manufactured by Nihon
Unicar), and silica microparticle Aerosil (registered trade mark)
R805 (trade name, manufactured by Japan Aerosil, primary particle
size: 17 nm) were used. The aforementioned substances were
dissolved in a toluene/ethyl acetate solvent mixture in accordance
with the composition listed in Table 3 to obtain a varnish of an
adhesive resin composition.
[0152] After the varnish mixture was stirred to disperse, it was
applied onto a separator film (PET film) by a roll coater and then
dried in an oven of 70.degree. C. for 10 minutes to obtain a 25
.mu.m-thick transparency confirmation film on the separator film.
Subsequently, the same steps as in Comparative Example 1 were
repeated to obtain a 20 .mu.m-thick insulating adhesive layer of a
circuit-member connecting adhesive on the separator.
Comparative Example 5
[0153] As a crosslinkable resin, an epoxy resin NC7000 (trade name,
manufactured by Nippon Kayaku Co., Ltd.) was used. As a hardening
agent reacting with the crosslinkable resin, phenol-aralkyl resin
XLC-LL (trade name, manufactured by Mitsui Chemicals Inc.) was
used. In place of the microencapsulated hardening agent, liquid
epoxy resin Epicoat 828 (trade name, manufactured by Japan Epoxy
Resins Co., Ltd.) and a hardening agent 2PHZ (trade name,
manufactured by Shikoku Chemicals Corporation) were used. As a
copolymerizable resin having a molecular weight of 1 million or
less and a Tg of 40.degree. C. or less and containing at least one
functional group reactive to the crosslinkable resin in a side
chain, an epoxy-group containing acrylic rubber HTR-860P-3 (trade
name, manufactured by Nagase ChemteX Corporation, weight average
molecular weight: 0.3 million), a silane coupling agent SH6040
(trade name, manufactured by Toray Dow Corning Silicone, Co., Ltd.)
and silica microparticle Aerosil (registered trade mark) R805
(trade name, manufactured by Japan Aerosil, primary particle size:
17 nm) were used. The aforementioned substances were dissolved in a
toluene/ethyl acetate solvent mixture in accordance with the
composition listed in Table 3 to obtain a varnish of an adhesive
resin composition.
[0154] After the varnish mixture was stirred to disperse, it was
applied onto a separator film (PET film) by a roll coater and then
dried in an oven of 70.degree. C. for 10 minutes to obtain a 25
.mu.m-thick transparency confirmation film on the separator film.
Subsequently, the same steps as in Comparative Example 1 were
repeated to obtain a 20 .mu.m-thick insulating adhesive layer of a
circuit-member connecting adhesive.
Comparative Example 6
[0155] A varnish for an adhesive resin composition was prepared in
accordance with the composition listed in Table 3 in the same
manner as in Example 1 except that the cordierite particles of
Example 1 were replaced by silica microparticle Aerosil (registered
trade mark) R805 (trade name, manufactured by Japan Aerosil,
primary particle size: 17 nm). Thereafter, a transparency
confirmation film was prepared and simultaneously an insulating
adhesive layer of a circuit-member connecting adhesive was
obtained.
TABLE-US-00003 TABLE 3 Trade name or Comparative Example material
name 1 2 3 4 5 6 NC7000 15 15 15 50 15 15 Epicoat 828 -- -- -- --
30 -- XLC-LL 15 15 15 -- 15 15 HTR-860P-3 20 20 20 50 20 20
HX-3941HP 50 50 50 -- -- 50 2PHZ -- -- -- 1.25 1.25 -- SH6040 1 1 1
-- 1 1 SH6062 -- -- -- 0.75 -- -- A1160 -- -- -- 1.5 -- -- SE2050
100 25 -- -- -- -- R805 -- -- -- 15 15 15 (Unit: part by
weight)
Comparative Examples 7 to 12
[0156] Transparency confirmation films having compositions listed
in Table 2 were prepared in the same procedures as mentioned above
except that conductive particles of 3 .mu.m in average particle
size, which were formed by providing a 0.2 .mu.m-thick nickel layer
on the surface of particles having a polystyrene core and providing
a 0.04 .mu.m thick gold layer outside the nickel layer, were mixed
with the insulating adhesive layers obtained in Comparative Example
1 to 6 and a 5 .mu.m-thick particle layer of a circuit-member
connecting adhesive was obtained on the transparency confirmation
films. The insulating adhesive layer and the particle layer were
bonded by a laminator to obtain a 25 .mu.m-thick circuit-member
connecting anisotropic conductive adhesive.
TABLE-US-00004 TABLE 4 Trade name or Comparative Example material
name 7 8 9 10 11 12 NC7000 15 15 15 50 15 15 Epicoat 828 -- -- --
-- 30 -- XLC-LL 15 15 15 -- 15 15 HTR-860P-3 20 20 20 50 20 20
HX-3941HP 50 50 50 -- -- 50 2PHZ -- -- -- 1.25 1.25 -- SH6040 1 1 1
-- 1 1 SH6062 -- -- -- 0.75 -- -- A1160 -- -- -- 1.5 -- -- SE2050
100 25 -- -- -- -- R805 -- -- -- 15 15 15 Conductive 5 vol % 5 vol
% 5 vol % 5 vol % 5 vol % 5 vol % particles (Unit: part by
weight)
[0157] (Laminate of Semiconductor Wafer/Circuit-Member Connecting
Adhesive/Dicing Tape)
[0158] An adsorption stage of a die attach film mounter
manufactured by JCM Co., Ltd. was heated to 80.degree. C.
Thereafter, a semiconductor wafer of 6-inch in diameter and 150
.mu.m in thickness having gold-plated bumps formed thereon were
mounted on the adsorption stage with a bump-side surface facing
up.
[0159] The circuit-member connecting adhesives of Examples 1 to 5
and Comparative Examples 1 to 6 attached with separators were cut
into pieces having a dimension of 200 mm.times.200 mm, which were
laminated with an insulating adhesive layer side facing the bump
side of the semiconductor wafer by pressing by the bonding roller
of the die attach mounter from an end of the semiconductor wafer so
as not to include air.
[0160] After the lamination, the portion of the adhesive running
off the outer edge of the wafer was cut away. After cutting, the
separator was peeled off and then a laminate of the wafer and the
circuit-member connecting adhesive (from which the separator was
already peeled off) was mounted on the adsorption stage of the die
attach film mounter set at 40.degree. C. with the surface attached
with the adhesive facing up. Furthermore, a dicing frame for a
12-inch wafer was arranged along the circumference of the
wafer.
[0161] UV-curable dicing tape UC-334EP-110 (trade name,
manufactured by The Furukawa Electric Co., Ltd.) was laminated with
a sticky surface facing the semiconductor wafer by pressing by the
bonding roller of the die attach mounter from an end of the dicing
frame so as not to include air.
[0162] After the lamination, the dicing tape was cut in the middle
between the outer circumference and the inner circumference of the
dicing frame to obtain a laminate of a semiconductor
wafer/circuit-member connecting adhesive/dicing tape fixed on the
dicing frame.
[0163] (Dicing)
[0164] The laminate of a semiconductor/circuit-member connecting
adhesive/dicing tape fixed on the dicing frame was mounted on a
full-automatic dicing saw DFD6361 (trade name) manufactured by
Disco Corporation with the back-grind surface of the semiconductor
wafer facing up. Alignment of a scribe line was performed through
the wafer by use of an IR camera.
[0165] In the first stage, cut was made to 100 .mu.m from the
back-grind surface. The remaining wafer, circuit-member connecting
adhesive and the part of the dicing tape were cut at intervals of
15.1 mm in the long side direction and at intervals of 1.6 mm in
the short side direction. After cutting, washing was performed and
moisture was blown out by blowing and then UV rays were applied to
the dicing tape. Thereafter, the dicing tape was pushed up toward
the semiconductor wafer to obtain semiconductor chips of 15.1
mm.times.1.6 mm having a circuit-member connecting adhesive formed
on the bump side.
(Pressure-Bonding)
[0166] The chip was suctioned in such a manner that the back-grind
surface of the semiconductor chip with the circuit-member
connecting adhesive faces the adsorption head of an ultrasonic
flip-chip bonder SH-50MP (trade name, manufactured by Altecs Co.,
Ltd.). The chips was irradiated with light using a halogen light
source manufactured by Moritex Corporation and a light guide from
the circuit-member connecting adhesive side to recognize an
alignment mark formed on the surface of the semiconductor chip. In
this way, alignment was performed.
[0167] On the other hand, an alignment mark formed of ITO on a
board having 1400 angstrom-thick indium-tin oxide (ITO) film
electrodes formed on a 0.7 mm-thick non-alkali glass, was
recognized and aligned. Thereafter, a chip was pressed at 0.5 MPa
for one second on the glass board without heating. In this manner,
a semiconductor chip was provisionally fixed on the glass board
with the circuit-member connecting adhesive interposed between
them.
[0168] Subsequently, the chip was pressed on the glass under the
conditions: temperature: 210.degree. C. and pressure: 50 MPa, for 5
seconds and simultaneously the adhesive was hardened. In this
manner, bonding between the bump and the ITO electrodes and
adhesion between the chip and the glass board were completed. After
the pressure-bonding, a connection resistance value was
checked.
[0169] After a connection resistance value was checked, the
semiconductor chip-glass board united body was placed in a
high-temperature/humidity apparatus (60.degree. C. and 90% RH) or a
cycle tester (-40.degree. C., 15 minutes and 100.degree. C., 15
minutes) in order to check the connection reliability of the
circuit-member connecting adhesive. After a certain time period, a
change in connection resistance was measured.
[0170] (Measurement of Linear Expansion Coefficient)
[0171] Each of the circuit-member connecting adhesives according to
Examples and Comparative Examples was placed together with a
separator in an oven set at 180.degree. C. for 3 hours to perform a
heat hardening treatment. After heat hardening, the film was peeled
off from the separator and cut into pieces of 30 mm.times.2 mm in
size. Using TMA/SS6100 (trade name, manufactured by Seiko
Instruments Inc. (after the distance of chucks was set at 20 mm)),
thermo mechanical analysis was performed in the conditions:
measurement temperature range: 20.degree. C. to 300.degree. C.,
temperature raising rate: 5.degree. C./min, loading condition: 0.5
MPa-pressure/sectional area, in accordance with a tensile test mode
to obtain a linear expansion coefficient.
[0172] (Measurement of Reactivity)
[0173] Each of the circuit-member connecting adhesives according to
Examples and Comparative Examples (2 to 10 mg) was weighed in an
aluminum measurement container and measured for a calorific value
by DSC Pylis 1 (trade name) manufactured by Perkin Elmer, Inc in
the range from 30 to 300.degree. C., at a temperature raising rate
of 20.degree. C./min. This is regarded as an initial calorific
value.
[0174] Subsequently, the temperature of the heat head of a
thermocompression bonding apparatus was set at a temperature such
that temperature reached 180.degree. C. in 20 seconds after the
temperature was confirmed by a thermocouple sandwiched between
separators. The circuit-member connecting adhesive sandwiched
between separators was heated for 20 seconds by the heating head
set at the conditions. In this way, a film to which the same heat
treatment as a thermocompression bonding process was applied was
obtained. After the heat treatment, the film (2 to 10 mg) was
weighed and placed in an aluminum measurement container and
subjected to calorific value measurement performed by DSC from 30
to 300.degree. C. at a temperature increased rate of 20.degree.
C./min. This is regarded as a calorific value after heating. A
reactivity (%) was calculated from the calorific values obtained,
in accordance with the following formula:
(Initial calorific value-calorific value after heating)/(initial
calorific value).times.100.
[0175] Properties of the circuit-member connecting adhesives, more
specifically, parallel transmittance, linear expansion coefficient
after hardening, whether a recognition mark is observed or not by a
flip-chip bonder, reactivity and further a connection resistance
value after pressure-bonding, and a connection resistance value
after the reliability test are shown in Tables 5 and 6 with respect
to each of Examples and Comparative Examples.
TABLE-US-00005 TABLE 5 Example Item 1 2 3 4 5 6 7 Parallel 18 25 29
33 32 29 18 transmittance (%) Linear expansion 38 48 58 69 26 58 35
coefficient (40-100.degree. C.) (.times.10.sup.-6/.degree. C.)
Recognition of chip Recognized Recognized Recognized Recognized
Recognized Recognized Recognized alignment mark Reactivity (%) 89
88 89 86 89 89 92 Connection 0.2 0.4 0.5 4.7 1.6 -- -- resistance
after pressure-bonding (.OMEGA.) Connection 48 60 220 330 150 -- --
resistance after high- temperature/humidity test (200 h) (.OMEGA.)
Connection 20 40 100 200 60 -- -- resistance after temperature
cycle test (200 cycles) (.OMEGA.)
TABLE-US-00006 TABLE 6 Comparative Example Item 1 2 3 4 5 6
Parallel 2 7 60 15 45 47 transmittance (%) Linear expansion 42 82
88 170 102 87 coefficient (40-100.degree. C.)
(.times.10.sup.-6/.degree. C.) Recognition of chip Not Not
Recognized Recognized Recognized Recognized alignment mark
recognized recognized Reactivity (%) 88 86 88 1 0 86 Connection
Conductive Conductive 10.2 Conductive Conductive 0.7 resistance
after failure failure failure failure pressure-bonding (.OMEGA.)
Connection -- -- Conductive -- -- Conductive resistance after high-
failure failure temperature/humidity test (200 h) (.OMEGA.)
Connection -- -- Conductive -- -- Conductive resistance after
failure failure temperature cycle test (200 cycles) (.OMEGA.)
[0176] As shown in Table 5, the circuit-member connecting adhesives
employing cordierite or aluminum borate having a refractive index
of 1.5 to 1.7 as composite oxide particles have a parallel
transmittance of 15% or more and a turbidity of 85% or less.
Therefore, it is possible to recognize a recognition mark on a chip
circuit surface through the adhesive by use of a recognition system
of a flip-chip bonder. Since composite oxide particles having a low
thermal expansion coefficient are contained, the linear expansion
coefficient after hardening is reduced. In addition, in the
connection reliability test, the reactivity reaches 80% or more in
the heating conditions during a thermocompression bonding process
where no conductive failure occurs. It is confirmed that a low
connection resistance can be stably shown. Therefore, it is
apparent that they are excellent adhesives for flip-chip
connection.
[0177] On the other hand, as shown in Table 5, in Comparative
Examples 1 and 2, the turbidities are large and the parallel
transmittances are low since silica having a refractive index of
1.46 is used. A recognition operation cannot be performed by a
flip-chip bonder and alignment cannot be performed. As a result,
the semiconductor apparatus cannot ensure initial conductivity. In
Comparative Example 3, since composite oxide particles are not
added, a linear expansion coefficient is large, causing conductive
failure. In Comparative Examples 4 and 5, the reactivity is low and
rapid hardening cannot be made. As a result, conductive failure
occurs in the semiconductor device. Furthermore, in Comparative
Example 6, since Aerosil (registered trade mark) has a large
specific surface area, the amount that can be blended to a resin is
low. Because of the low content, it is difficult to reduce a linear
expansion coefficient. As a result, disadvantages such as
conductive failure inevitably occur.
INDUSTRIAL APPLICABILITY
[0178] The film-type adhesive for connecting circuit members of the
present invention can provide a semiconductor chip with an adhesive
for use in a preset underfill method capable of dealing with
narrow-pitch and narrow-gap tendency without causing contamination
during a dicing process and capable of peeling off from a dicing
tape after dicing; furthermore can be used as a rapid-hardening
circuit-member connecting adhesive for applying to a wafer capable
of attaining not only transparency for realizing accurate alignment
of adhesive chips but also high connection reliability due to a low
thermal expansion coefficient.
* * * * *