U.S. patent application number 10/138485 was filed with the patent office on 2002-10-31 for circuit tape having adhesive film, semiconductor device, and a method for manufacturing the same.
Invention is credited to Anjoh, Ichiro, Eguchi, Shuji, Hattori, Rie, Ishii, Toshiak, Kitano, Makoto, Kokaku, Hiroyoshi, Mita, Mamoru, Miyazaki, Chuichi, Morishima, Makoto, Nagai, Akira, Ogino, Masahiko, Okabe, Norio, Segawa, Masanori, Tsubosaki, Kunihiro, Tsuyuno, Nobutake.
Application Number | 20020160185 10/138485 |
Document ID | / |
Family ID | 15168704 |
Filed Date | 2002-10-31 |
United States Patent
Application |
20020160185 |
Kind Code |
A1 |
Nagai, Akira ; et
al. |
October 31, 2002 |
Circuit tape having adhesive film, semiconductor device, and a
method for manufacturing the same
Abstract
A semiconductor device having a superior connection reliability
is obtained by providing a buffer body for absorbing the difference
of thermal expansion between the mounting substrate and the
semiconductor element in a semiconductor package structure, even if
an organic material is used for the mounting substrate. A film
material is used as the body for buffering the thermal stress
generated by the difference in thermal expansion between the
mounting substrate and the semiconductor element. The film material
has modulus of elasticity of at least 1 MPa in the reflow
temperature range (200-250.degree. C.).
Inventors: |
Nagai, Akira; (Hitachi-shi,
JP) ; Eguchi, Shuji; (Naka-gun, JP) ; Ogino,
Masahiko; (Hitachi-shi, JP) ; Segawa, Masanori;
(Hitachi-shi, JP) ; Ishii, Toshiak; (Hitachi-shi,
JP) ; Tsuyuno, Nobutake; (Hitachi-shi, JP) ;
Kokaku, Hiroyoshi; (Hitachi-shi, JP) ; Hattori,
Rie; (Hitachinaka-shi, JP) ; Morishima, Makoto;
(Hitachi-shi, JP) ; Anjoh, Ichiro; (Tokyo, JP)
; Tsubosaki, Kunihiro; (Tokyo, JP) ; Miyazaki,
Chuichi; (Tokyo, JP) ; Kitano, Makoto;
(Tsuchiura-shi, JP) ; Mita, Mamoru; (Hitachi-shi,
JP) ; Okabe, Norio; (Hitachi-shi, JP) |
Correspondence
Address: |
ANTONELLI TERRY STOUT AND KRAUS
SUITE 1800
1300 NORTH SEVENTEENTH STREET
ARLINGTON
VA
22209
|
Family ID: |
15168704 |
Appl. No.: |
10/138485 |
Filed: |
May 6, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10138485 |
May 6, 2002 |
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09493208 |
Jan 28, 2000 |
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09493208 |
Jan 28, 2000 |
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08857674 |
May 16, 1997 |
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6114753 |
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Current U.S.
Class: |
428/354 ;
257/E23.039; 257/E23.124; 428/343 |
Current CPC
Class: |
H01L 2924/01045
20130101; H01L 2924/10329 20130101; H01L 2224/48091 20130101; H01L
2924/01006 20130101; Y10T 156/107 20150115; H01L 2924/01029
20130101; Y10T 428/2848 20150115; H01L 2924/181 20130101; H01L
2924/01082 20130101; H01L 2924/01005 20130101; H01L 2924/1532
20130101; H01L 2924/30107 20130101; H01L 2924/00014 20130101; H01L
23/3107 20130101; H01L 2924/01078 20130101; H01L 24/48 20130101;
H01L 2924/351 20130101; H01L 2924/01079 20130101; H01L 2224/04042
20130101; H01L 2224/0401 20130101; H01L 2224/05553 20130101; Y10T
428/28 20150115; H01L 2224/4824 20130101; Y10T 428/249955 20150401;
H01L 2924/01014 20130101; H01L 2924/01087 20130101; H01L 2924/15311
20130101; H01L 23/4951 20130101; H01L 2924/014 20130101; H01L
2924/01033 20130101; H01L 2224/06136 20130101; H01L 2924/12042
20130101; H01L 24/06 20130101; H01L 2224/48 20130101; H01L
2924/01027 20130101; H01L 2224/48091 20130101; H01L 2924/00014
20130101; H01L 2924/351 20130101; H01L 2924/00 20130101; H01L
2924/181 20130101; H01L 2924/00 20130101; H01L 2924/12042 20130101;
H01L 2924/00 20130101; H01L 2924/00014 20130101; H01L 2224/45099
20130101; H01L 2924/00014 20130101; H01L 2224/05599 20130101; H01L
2924/00014 20130101; H01L 2224/85399 20130101; H01L 2924/00014
20130101; H01L 2224/45015 20130101; H01L 2924/207 20130101; H01L
2224/48 20130101; H01L 2924/00 20130101 |
Class at
Publication: |
428/354 ;
428/343 |
International
Class: |
B32B 007/12; B32B
015/04 |
Foreign Application Data
Date |
Code |
Application Number |
May 30, 1996 |
JP |
8-136159 |
Claims
What is claimed is:
1. A circuit tape with an adhesive layer, for semiconductor
devices, comprising: a circuit tape having a base material made of
a dielectric film, whereon a circuit is formed; and an adhesive
layer for connecting said circuit tape to a semiconductor element
such that the circuit tape is insulated from the semiconductor
element, wherein an elastic modulus of said adhesive layer, in a
range of mounting reflow temperature for mounting the semiconductor
element onto a mounting substrate, is more than 1 MPa.
2. A circuit tape with an adhesive layer, for semiconductor
devices, as claimed in claim 1, wherein the elastic modulus of said
adhesive layer, in the range of 200.quadrature.-250.quadrature.C,
is more than 1 MPa.
3. A circuit tape with an adhesive layer, for semiconductor
devices, as claimed in claim 1, wherein said adhesive layer is
composed of an adhesive film.
4. A circuit tape with an adhesive layer, for semiconductor
devices, as claimed in claim 3, wherein said adhesive film includes
a three-layer structure having a porous support layer and two
adhesive layers which are respectively applied onto both sides of
said porous support layer.
5. A circuit tape with an adhesive layer, for semiconductor
devices, as claimed in claim 3, wherein said adhesive film includes
a structure wherein an adhesive agent is impregnated into a porous
support.
6. A circuit tape with an adhesive layer, for semiconductor
devices, as claimed in claim 3, wherein an elastic modulus of said
adhesive film at room temperature is equal to or less than 4000
MPa.
7. A circuit tape with an adhesive layer, for semiconductor
devices, as claimed in claim 1, wherein an elastic modulus of the
adhesive layer at room temperature is lower than the elastic
modulus of said adhesive layer in a temperature range of
200.quadrature.-250.quadrature.C.
8. A circuit tape with an adhesive layer, for semiconductor
devices, as claimed in claim 1 , wherein the adhesive layer has a
layer of a thermoplastic resin, and the thermoplastic resin has a
glass transition temperature greater than 250.quadrature.C.
9. A circuit tape with an adhesive layer, for semiconductor
devices, as claimed in claim 1, wherein material of the adhesive
layer has a coefficient of moisture absorption at
85.quadrature.C/85% RH for 168 hours of, at most, 3%.
10. A circuit tape with an adhesive layer, for semiconductor
devices, as claimed in claim 1, wherein the adhesive layer includes
a thermosetting resin closest to the circuit tape and a
thermoplastic resin to be closest to the semiconductor element.
11. A circuit tape with an adhesive layer, for semiconductor
devices, as claimed in claim 1, wherein the circuit tape has an
uneven surface with space between portions of the circuit, and the
adhesive layer fills in the spaces.
12. A circuit tape with an adhesive layer, for semiconductor
devices, comprising: an elongated circuit tape having a base
material made of dielectric film, whereon circuits are formed; and
at least one adhesive film each adhered continuously to said
circuit tape, each adhesive film having a size less than that of
the elongated circuit tape.
13. A circuit tape with an adhesive layer, for semiconductor
devices, as claimed in claim 12, wherein an elastic modulus of said
adhesive film, in a range of mounting reflow temperature for
mounting a semiconductor element onto a mounting substrate, is more
than 1 MPa.
14. A circuit tape with an adhesive layer, for semiconductor
devices, as claimed in claim 13, wherein an elastic modulus of said
adhesive film, in the range of 200.quadrature.-250.quadrature.C, is
more than 1 MPa.
15. A circuit tape with an adhesive layer, for semiconductor
devices, as claimed in claim 12, wherein said adhesive film
includes a three-layer structure having a support layer and two
adhesive layers which are respectively applied onto both sides of
said support layer.
16. A circuit tape with an adhesive layer, for semiconductor
devices, as claimed in claim 12, wherein said adhesive film
includes a structure wherein an adhesive agent is impregnated into
a porous support.
17. A circuit tape with an adhesive layer, for semiconductor
devices, as claimed in claim 13, wherein an elastic modulus of said
adhesive film, at room temperature, is equal to or les s than 4000
MPa.
18. A method of manufacturing a circuit tape with an adhesive
layer, for semiconductor devices, comprising the steps of:
transferring an elongated circuit tape, whereon a circuit is
formed, from a first reel to a second reel; punching out adhesive
film of a size smaller than that of the elongated circuit tape; and
adhering continuously the punched-out adhesive film to said circuit
tape, as the circuit tape is transferred from the first reel to the
second reel, concurrently with the punching.
19. A method of manufacturing circuit tape with an adhesive layer,
for semiconductor devices, as claimed in claim 18, wherein said
punched-out adhesive film is punched out from an elongated adhesive
film transferred from a first reel to a second reel.
20. Adhesive film for semiconductor devices, which is for adhering
a semiconductor element to circuit tape, having an elastic modulus,
in a range of mounting reflow temperature for mounting the
semiconductor element onto a mounting substrate, of more than 1
MPa.
21. Adhesive film for semiconductor devices as claimed in claim 20,
wherein said mounting reflow temperature is in a range of
200.quadrature.C-250.quadrature.C, said elastic modulus of the
adhesive film, in the range of 200.quadrature.C-250.quadrature.C,
being more than 1 MPa.
22. Adhesive film for semiconductor devices as claimed in claim 20,
wherein said elastic modulus at room temperature is equal to or
less than 4000 MPa.
23. Adhesive film for semiconductor devices as claimed in claim 20,
wherein said adhesive film includes a three-layer structure having
a support layer and two adhesive agent layers which are applied
respectively onto both sides of said support layer.
24. Adhesive film for semiconductor devices as claimed in claim 20,
wherein said adhesive film has a structure wherein an adhesive
agent is impregnated into a porous support.
Description
[0001] This application is a Continuation application of
application Ser. No. 09/493,208, filed Jan. 28, 2000, which is a
Divisional application of application Ser. No. 08/857,674, filed
May 16, 1997.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a circuit tape, a
semiconductor device, and a method of manufacturing the same, which
are superior in electrical characteristics, mounting reliability,
and assembling easiness, and are responsive to the requirements for
high density mounting, multipins mounting, and fast
transmittance.
[0003] Currently, in the continuing effort to improve electronic
devices to provide high performance, the demand for high
integration and high density mounting of semiconductor elements has
become strong. Therefore, semiconductor elements have been improved
to achieve high integration and high performance, such as in LSI,
VLSI, and ULSI devices, and there has been increase in the
capacity, the number of pins, the speed, and power consumption
thereof. In responding to such advances, the package structure of
the semiconductor device for multipins has been changed from a
structure, in which connecting terminals are provided at two sides
of the semiconductor element, to an advanced structure, in which
the connecting terminals are provided at all four sides of the
semiconductor element. Furthermore, in order to respond to
increasing the number of pins, a grid array structure has come to
be used in practice. The grid array structure is a structure of a
semiconductor element, in which the connecting terminals are
provided in a grid array over the entire mounting surface of the
semiconductor element by using a multilayer carrier substrate. The
grid array structure includes a ball grid array structure (BGA),
which has a shortened connecting terminal length in order to make
fast signal transmission possible. The ball type structure of the
connecting terminal increases the width of its conductor;
therefore, the ball structure is also effective in decreasing
inductance. Currently, in order to respond to the requirement for
fast signal transmission, organic materials haying a relatively low
dielectric constant have been investigated for use in the
multilayer carrier substrate. However, the organic materials have
generally a larger thermal expansion coefficient than the
semiconductor element, and so thermal stress generated by the
difference in thermal expansion becomes a problem from the point of
view of connection reliability, and so on. Recently, a structure
which does not use a carrier substrate has been proposed for the
BGA package.
[0004] More particularly, a new semiconductor element package
structure has been disclosed (U.S. Pat. No. 5,148,265), in which
the connection reliability is improved by using an elastomer
material having a low modulus of elasticity for reducing the
thermal stress generated by the difference in thermal expansion
between the semiconductor element and the mounting substrate. The
proposed package structure uses a circuit tape composed of a
polyimide and the like, instead of a carrier substrate, for
electrically connecting the semiconductor element and the mounting
substrate. Therefore, the electrical connections between the
semiconductor element and the circuit tape are effected by a wire
bonding method or a bonding connection with leads, and the circuit
tape and the mounting substrate are electrically connected by
soldering ball terminals. As the elastomer material of the prior
art, a silicone material is generally used since this is a material
having a low modulus of elasticity and a superior heat resistance.
As a general method for forming a stress buffer layer with a
silicone material, the steps of printing an uncured liquid resin on
the circuit tape using masks, and subsequently, curing the printed
resin, are generally used. However, the above method has problems,
such as a difficulty in maintaining the flatness of the buffer
layer obtained by the printing, and the complexity of the printing
process, which requires a long time for the printing, is
disadvantageous. Accordingly, the above method is not suitable for
a mass-production process, and so the problems which undesirably
affect the assembling yield and reliability of mounting caused by
the difficulty in maintaining the flatness of the buffer layer are
yet to be solved.
SUMMARY OF THE INVENTION
[0005] One of the objects of the present invention is to provide a
method of obtaining a stress buffer layer which is superior in
flatness by using a film material as the elastomer material for
reducing the thermal stress in the semiconductor devices, thereby
obtaining semiconductor devices which are superior in mass
productivity.
[0006] In order to realize the above object, the present invention
provides the following measures.
[0007] The measures can be achieved by providing a semiconductor
device comprising a circuit tape having a pattern layer connected
electrically to a semiconductor element, an external terminal
provided on the circuit tape for electrically connecting the
circuit tape to a mounting substrate, and film material for causing
the circuit tape to adhere to the semiconductor element while
maintaining an insulation condition between the circuit tape and
the semiconductor element, wherein the film material for effecting
the adhering has a physical property such that the modulus of
elasticity of the film material in the temperature range of a
solder reflow condition for mounting (200-250.degree. C.) is at
least 1 MPa.
[0008] The above film material for effecting the adhering is passed
through a process for forming an external terminal, such as a
solder ball and the like, for connecting the mounting substrate and
the circuit tape, or a solder reflow process for mounting the
semiconductor element of the present invention onto a mounting
substrate in the manufacturing process of the semiconductor devices
The reflow temperature is generally a high temperature in the range
of 200-250.degree. C. Therefore, if the semiconductor device
contains moisture, the moisture evaporates during the heat
treatment, and the film material swells due to the vapor pressure
of the moisture. When the swelling exceeds a threshold value, a
foaming phenomenon is generated, and defects, such as void
formation, delamination, and the like, are generated. Therefore,
the film material to be used is required to have as low a moisture
absorption rate as possible and a high modulus of elasticity in the
range of the reflow temperature. In accordance with the present
invention, various film materials have been studied, and it was
found that the adhesive materials having a modulus of elasticity in
the temperature range of a reflow process of at least 1 MPa had
superior reflow characteristics. Several examples of the
temperature dependence of the modulus of elasticity of the material
are shown in FIG. 1.
[0009] Furthermore, it was found that when materials, of which the
modulus of elasticity in the temperature range of the mounting
reflow condition was maintained at least at 1 MPa, were used, a
preferable result in the anti-reflow characteristics could be
obtained. The amount of swelling depends on the ratio of the vapor
pressure and the modulus of elasticity, and the higher the modulus
of elasticity is, the less will be the amount of swelling. The
foaming phenomenon is generated when the amount of swelling exceeds
the break elongation, one of the mechanical properties of the
material. Furthermore, the modulus of elasticity correlates with
the mechanical strength of the adhesive film material, and
generally, the higher the modulus of elasticity is, the greater
will be the tendency to increase the break stress and break
elongation. Therefore, by using a material having a high modulus of
elasticity in the range of the reflow temperature, the reflow
characteristics can be improved as to both the swelling amount and
the mechanical characteristics. In the above case, the adhesive
film material may be either a thermosetting resin or a
thermoplastic resin.
[0010] The adhesive layer is sometimes composed of either sticky
adhesive agents or sticky-cohesive adhesive agents, in addition to
the adhesive agents made of the above material. In order to
maintain the modulus of elasticity at least at 1 MPa in the
temperature range of the reflow process, the thermoplastic resin
preferably has a glass transition temperature, i.e. a changing
point of modulus of elasticity, which is higher then the
temperature range (200-250.degree. C.) of the reflow process. The
thermosetting resin is required to have a chemical or physical
crosslinking structure to a certain degree at a temperature in the
rubber region, which is higher than the glass transition
temperature. That is, the modulus of elasticity in the rubber
region is generally proportional to the crosslinking density, and
the crosslinking density must be increased in order to increase the
modulus of elasticity. The film material is desirably composed of a
resin having a low modulus of elasticity which is at the utmost
4000 MPa at room temperature, in order to operate as a stress
buffer layer.
[0011] As one of characteristics of a film material, the
coefficient of moisture absorption at 85.degree. C./85% RH for 168
hours is desirably, at the utmost, 3% in view of the reflow
characteristics. As the film material, materials having a low
modulus of elasticity, except for a silicone material, can be used.
The structure of the film material is not restricted to a
homogeneous structure composed of an adhesive agent component, but
also, for instance, a three layer structure having adhesive layers
at both surfaces of a supporter, respectively, or a structure in
which the adhesive agent is impregnated into a porous supporter,
can be used. As shapes of the film, various shapes manufactured by
stamping, a mesh-like shape, and the like can be used. The
mesh-like shape is effective in improving the anti-reflow property
at the moisture absorbing time, because the adhesion area can be
decreased.
[0012] In the case of a multilayer structure represented by a three
layer structure, the supporter and the adhesive layer can be
composed of a combination of at least two kinds of the above
adhesive agents, the sticky adhesive agents, the sticky-cohesive
adhesive agents, and the like. The adhesive layer is located at
each of both of the surfaces of the supporter, and each adhesive
layer can be formed of a different kind of material from the other.
For instance, a combination is usable in which a thermosetting
resin having a high fluidity is used in order to flatten or
eliminate the unevenness of the pattern layer of the circuit tape
side, and a thermoplastic resin, which can be adhered in a short
time at a high temperature, is used at the opposite flat portion
for adhering to the semiconductor element.
[0013] A set of schematic illustrations indicating a flow of a
general fabrication process for the manufacture of semiconductor
devices, according to the present invention, is shown in FIG.
2.
[0014] The process can be divided into three representative
sections. The first one, including STEPS 1-5 (FIG. 2a), is a method
for fabricating a semiconductor element comprising (1) the step 1
of applying an adhesive film to the tape having a pattern layer,
(2) the step 2 of adhering the tape having a pattern layer to the
semiconductor element by means of the adhesive film while
maintaining an insulating condition therebetween, (3) the step 3 of
electrically connecting the pattern layer formed on the tape and
the pad on the semiconductor element, (4) the step 4 of sealing the
electrically connected portion with an insulating agent, and (5)
the step 5 of forming an external terminal on the tape for
connection to the mounting substrate.
[0015] The above method is effective in improving the
processability, because the circuit tape and the film material can
be handled in the manner of a reel to reel process, as will be
explained later.
[0016] The second one, including STEPS 6-10, (FIG. 2b), is a method
for fabricating a semiconductor element comprising (1) the step 6
of applying an adhesive film to the semiconductor element, (2) the
step 7 of adhering the tape having a pattern layer to the
semiconductor element by means of the adhesive film while
maintaining an insulating condition therebetween, (3) the step 8 of
electrically connecting the pattern layer formed on the tape and
the pad on the semiconductor element, (4) the step 9 of sealing the
electrically connected portion with an insulating agent, and (5)
the step 10 of forming an external terminal on the tape for
connection to the mounting substrate.
[0017] The above method is effective in improving the production
yield of the semiconductor element itself. In accordance with the
method, the stress buffer layer can be formed on the semiconductor
element at the wafer stage condition.
[0018] The third one, including STEPS 11-14, (FIG. 2c), is a method
of fabricating a semiconductor clement comprising (1) the step 11
of setting the tape having the pattern layer in registration and
adhering the tape to the semiconductor element using the adhesive
film simultaneously with maintaining an insulating condition
therebetween, (2) the step 12 of electrically connecting the
pattern layer formed on the tape and the pad on the semiconductor
element, (3) the step 13 of sealing the electrically connected
portion with an insulating agent, and (4) the step 14 of forming an
external terminal on the tape for connection to the mounting
substrate.
[0019] The above method is effective in shortening the
manufacturing time, because the number of steps in the process can
be decreased.
[0020] These methods essentially comprise the following steps. The
adhesive film material of the present invention is provided between
the tape material having the pattern layer and the semiconductor
element by adopting a certain method, and the tape material and the
semiconductor element are bonded together simultaneously or
sequentially under conditions of designated temperature, pressure,
and time. Subsequently, the pattern layer on the tape is
electrically connected to the connecting pad of the semiconductor
element. As examples of a connecting method using a connecting lead
previously formed on the circuit tape as a circuit for connection
with the semiconductor element, any one of a single point bonding
method, a gang bonding method, and the like can be used.
[0021] As another example of a method for connection, a method in
which the pattern layer and the semiconductor element are connected
with wire bonding can be adopted.
[0022] Then, the connecting portion is encapsulated with an
insulating material, and finally the external terminals, which are
electrically connected with the mounting substrate, are formed on
the circuit tape. As an external terminal, a solder ball is
generally used, and most of the solder ball is formed by plating.
Metals which may be used for the plating are gold, nickel, copper,
solder, and the like.
[0023] In order to improve the mass productivity in the
manufacturing process, the process for integrating the adhesive
film material with the circuit tape previously as shown in FIG. 2a
is important.
[0024] As a general method for the above process, a method
comprising the steps of transferring the tape, whereon the pattern
is formed, by a long reel apparatus, stamping out the adhesive film
into a designated shape, and adhering the adhesive film of the
designated shape onto the circuit tape, as shown in FIG. 3, is
effective for mass production. When the adhesive film is made of a
thermosetting resin, the adhesive film can be made to adhere to the
circuit tape while in an uncured A stage or a half-cured B stage.
The resin is then further cured to a condition of a final-cured C
stage during the step of adhering the obtained circuit tape, to
which the adhesive film is attached, to the semiconductor element.
Otherwise, if the adhesive agent reaches the condition of the final
cured C stage during the time that the adhesive film is adhered to
the circuit tape, sometimes, an adhesive layer is newly formed on
the cured film portion.
[0025] As a method for forming the adhesive layer, an application
method, a film adhering method, and the like are generally used.
The adhesive component is desirably not sticky at room temperature,
but if sticky, a mold releasing paper and the like is used.
[0026] FIG. 4 shows an example of the composition of a circuit tape
to which an adhesive film is attached. The circuit tape can be
adhered to the semiconductor element. If a thermosetting resin is
used for the adhesive layer at the circuit tape side and a
thermoplastic resin is used for the adhesive layer at the side
adhered to the semiconductor, the circuit tape having the adhesive
ability shown in FIG. 4 can be provided readily.
[0027] When the adhesive layer is composed of a thermoplastic,
sticky, or cohesive material, the conditions for the two steps to
adhere to the circuit tape and to the semiconductor element can be
set as quite the same with respect to each other. As opposed to the
case of a thermosetting resin, the curing reaction does not need to
be controlled at the intermediate stages, and so a manufacturing
process superior in workability can be provided.
[0028] When the adhesive layer is composed of a sticky or cohesive
material, the material is advantageous from the point of view of
avoiding warpage of the semiconductor element, because the material
can be adhered at room temperature. When the adhesive film is
initially combined with the circuit tape, the semiconductor element
is easily registered at the time of adhering to the circuit tape.
Accordingly, the jigs of the adhering apparatus can be simplified,
and the method becomes advantageous for mass production.
[0029] With the semiconductor device relating to the present
invention, the unevenness of the pattern circuit on the circuit
tape is sometimes eliminated by filling spaces with the adhesive
layer of the film. In this case, the suitability of the adhesive
layer for the filling can be confirmed at the step of combining the
circuit tape and the semiconductor element. Therefore, an
unsuitable adhesive layer can be eliminated before joining the
circuit tape to the semiconductor element, a loss of the
semiconductor can be avoided, and an advantageous increase in the
production yield can be attained.
[0030] Typical examples of a thermosetting resin and a
thermoplastic resin for the adhesive component of the film
materials are as follows: epoxy resin, polyimide resin, polyamide
resin, cyanate resin, isocyanate resin, fluorine-containing resin,
silicon-containing resin, urethane resin, acrylate resin, styrene
resin, maleimide resin, phenolic resin, unsaturated polyester
resin, diallyl phthalate resin, cyanamide resin, polybutadiene
resin, polyamideimide resin, polyether resin, polysulfone resin,
polyester resin, polyolefine resin, polystyrene resin, polyvinyl
chloride, transpolyisoprene resin, polyacetal resin, polycarbonate
resin, polyphenylene ether resin, polyphenylene sulfide resin,
polyacrylate resin, polyether imide resin, polyether sulfone resin,
polyether ketone resin, liquid crystalline polyester resin,
polyallylether nitrile resin, polybenzoimidazole resin, various
kinds of polymer blend, and polymer alloys, and the like.
[0031] The above examples of a thermosetting resin and a
thermoplastic resin involve materials having an adhesiveness
resulting from melting or softening of the material by heating. On
the contrary, the sticky or cohesive materials are materials having
an adhesiveness produced by pressurizing.
[0032] Typical examples of the sticky and cohesive materials are as
follows: various rubber groups, such as the silicone group, the
butadiene group and the isoprene group, acrylate groups, polyvinyl
ether groups, and the like. The cohesive material includes a room
temperature curing type, a type cured by heat, ultraviolet ray
irradiation, electron beam irradiation, and the like, a type cured
by concurrent use of an accelerator, and the like. The room
temperature curing type includes a moisture-reactive type which
reacts in the presence of moisture in the atmosphere, a
photo-reactive type which contains a photo-initiator, and an
anti-oxygen material which contains peroxide, and the like. The
thermosetting resin generally includes a crosslinking agent, such
as thiurum groups, phenol groups, isocyanate groups, and the like,
and adhesive components are crosslinked three-dimensionally to form
the adhesive layer at a designated temperature.
[0033] The material of the type cured by ultraviolet ray
irradiation, or electron beam irradiation, contains various
photo-initiators. The material of the type cured by concurrent use
of an accelerator includes a solution containing a reaction
accelerator and a crosslinking agent, which are applied onto the
surface of the sticky layer, wherein the adhesive layer is finally
formed by mixing the above two agents with a contact pressure and
reacting the two agents sequentially. For the cohesive agent of the
present invention, a thermosetting resin is relatively preferable
Using a thermosetting resin, a semiconductor device, which is
superior in mass productivity and reliability, can be provided by
the method comprising the steps of registering the circuit tape and
the semiconductor element at room temperature, bringing the wiring
tape and the semiconductor element into contact to form a set, and
elevating the temperature of a plurality of such sets to a
designated degree simultaneously in a container, such as a constant
temperature bath, for producing a curing reaction to ensure the
adhesive strength.
[0034] The modulus of elasticity of the adhesive film material is
preferably high at a high temperature region in view of the reflow
characteristics, but as low as possible at room temperature. In
this regard, the semiconductor element and the mounting substrate
generally have different thermal expansion coefficients from each
other, and a thermal stress is generated, when the mounting is
performed, at the external terminal, which is composed of a solder
ball and the like. Then, the reliability of the connection becomes
remarkably important.
[0035] If the modulus of elasticity of the adhesive film existing
between the semiconductor element and the mounting substrate is
low, the region of the adhesive layer becomes a stress buffer
layer, and this is advantageous from the point of view of the
connection reliability. The modulus of elasticity at room
temperature is desirably, at the utmost, 4000 MPa. More preferably,
the modulus of elasticity in the entire range of the heat cycling
test (-55.degree. C.-150.degree. C.) is, at the utmost, 2000 MPa.
As a material which has a high modulus of elasticity at a high
temperature and a relatively low elastic modulus in a range of a
low temperature including room temperature, sometimes silicone
group materials are used. A film material comprising a silicone
group material is one of the significantly important materials of
the present invention.
[0036] However, film materials, other than the silicone group
material having the above characteristics, are advantageous in
comparison with the silicone group material. That is, because of
the weak cohesive energy of silicon, cyclic low molecular weight
silicone group compounds are gradually decomposed thermally during
a long heat treatment, such as during storing at a high temperature
(for instance, at least 150.degree. C.), and this sometimes becomes
a cause of contamination to the environment.
[0037] The composition of the film material of the present
invention is not only a homogeneous structure composed of the
adhesive agent components, but also may be a three layer structure,
such as a supporter having adhesive agent layers at both surfaces
for instance, and a structure in which the adhesive agent is
impregnated into a porous supporter. As the supporter of the film
material, films or a porous material made of polyimide, epoxy,
polyethylene terephthalate, cellurose, acetate, fluorine-containing
polymer, and the like can be used.
[0038] As the shape of the film, the various shapes obtainable by
stamping out, a mesh-like shape, and the like can be used. The
mesh-like shape is effective in improving the anti-reflow properly
at the moisture absorbing time, because the adhesion area can be
decreased. The three layer structure can be controlled to an
arbitrary thickness and as to the kind of the adhesive layer
provided at both the surfaces of the supporter, and the fluidity of
the adhesive layer at the time of adhesion can be readily
controlled. Furthermore, the presence of an insulating layer is
ensured by the supporter located between the adhesive layers.
[0039] The value of vapor pressure of the adhesive material by
moisture absorption at the time of reflow can be maintained at a
low value by using the material, of which the film material has a
coefficient of moisture absorption at 85.degree. C./85% RH of, at
the utmost, 3%, and so preferable reflow characteristics can be
obtained.
[0040] The tape having a pattern layer is generally composed of a
flexible circuit substrate. That is, a polyimide group material
serving as the insulating layer, an epoxy group material, a
polyimide group material, a phenolic group material, a polyamide
group material, and the like are used as the adhesive layer with
the conductor. Generally, copper is used as the conductor. As the
wiring circuit, the copper is sometimes coated with nickel, gold
plating, and the like. As the flexible circuit substrate, a
material, which does not use the adhesive layer with the conductor,
but uses a copper layer formed directly onto the polyimide
insulating layer, is sometimes used.
[0041] The tape having a pattern layer is sometimes composed of a
multilayer wiring structure. In this case, a voltage layer, a
ground layer, and so on in addition to the signal layer can be
formed in the circuit tape, and so a semiconductor device which is
superior in electric characteristics can be provided.
[0042] Two typical arrangements of the pad terminal on the
semiconductor element for electrically connecting the tape material
having the pattern layer with the semiconductor element are as
follows.
[0043] The one is a peripheral pad arrangement as shown in FIG. 5.
In this case, there are different types of structure for the
arrangement of the external terminal of the semiconductor device,
as shown in FIGS. 6-1, 6-2, 6-3. That is, the case wherein the
external terminals are located under the semiconductor element (Fan
In type, FIG. 6 1), the case wherein the external terminals are
located outside the semiconductor element (Fan Out type, FIG. 6-2),
and the case wherein the external terminals are located at both
under and outside the semiconductor element (Fan In/Out type, FIG.
6-3) can be used.
[0044] Another example of the pad arrangement is the central
arrangement shown in FIG. 7. In this case, the semiconductor device
is composed of the structure shown in FIG. 8.
[0045] In accordance with the present invention, the semiconductor
element is a device wherein IC, LSI, and the like, such as
memories, logic devices, gate arrays, customs, power transistors,
and the like, are formed on a wafer comprising semiconductor
materials such as Si, GaAs, and the like, and the device has
terminals for connecting to a lead, bump, and the like.
[0046] In accordance with the present invention, the semiconductor
device comprising a tape having a pattern layer is used as an
interconnection between the semiconductor element and the mounting
substrate, which is superior in anti-reflow characteristics and
connection reliability, may be provided by using a film material
having a modulus of elasticity of at least 1 MPa in the reflow
temperature region (200-250.degree. C.), which is a high
temperature region, as the adhesive material while maintaining the
insulation between the circuit tape and the semiconductor element.
By using such a film material, a manufacturing method which is
superior in mass productivity to the conventional printing methods
can be provided
BRIEF DESCRIPTION OF THE DRAWINGS
[0047] These and other objects, features and advantages of the
present invention will be understood more clearly from the
following detailed description with reference to the accompanying
drawings, wherein:
[0048] FIG. 1 is a graph indicating temperature dependency of the
modulus of elasticity of materials;
[0049] FIGS. 2a, 2b, and 2c are schematic illustrations indicating
the manufacturing process of the semiconductor device of the
present invention, wherein FIG. 2a shows a method wherein the film
is adhered previously to the circuit tape, FIG. 2b shows a method
wherein the film is adhered previously to the semiconductor
element, and FIG. 2c shows a method wherein the circuit tape and
the semiconductor element are adhered together simultaneously via
the film;
[0050] FIG. 3 is a schematic diagram indicating the continuous
process for adhering the film using a long reel;
[0051] FIG. 4 is a schematic diagram showing a cross section
indicating the composition of a circuit tape having a film with an
adhesive agent layer;
[0052] FIG. 5 is a schematic diagram of a semiconductor element
having peripheral pads;
[0053] FIGS. 6-1, 6-2, 6-3 are schematic cross sections showing the
structure of semiconductor devices using the semiconductor elements
having the peripheral pads;
[0054] FIG. 7 is a schematic diagram showing a semiconductor
element having pads located at the center of the element; and
[0055] FIG. 8 is a schematic cross section showing the structure of
a semiconductor device using a semiconductor element having pads
located at the center of the element.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
EMBODIMENT 1
[0056] An epoxy group adhesive film (made by Hitachi Chemical Co.,
Ltd., AS 3000, 50 .mu.m thick) was registered, placed, and adhered
between a semiconductor element and circuit tape at 170.degree. C.
for one minute with a pressure of 50 kgf/cm.sup.2, and was then
post-cured at 180.degree. C. for 60 minutes in a constant
temperature bath. Subsequently, connecting leads on the circuit
tape were electrically connected to pads of the semiconductor
element by single point bonding. The connecting portion was
encapsulated with an epoxy encapsulant (made by Hitachi Chemical
Co., Ltd., RC021C). Finally, the semiconductor device shown in FIG.
6-1 was obtained by fixing the solder balls, which were connecting
terminals with the mounting substrate, onto the circuit tape.
[0057] After absorbing moisture in a constant temperature bath at
85.degree. C./85% RH for 168 hours, the obtained semiconductor
device was set in an infrared reflow apparatus with a maximum
temperature of 245.degree. C., and it was confirmed whether the
semiconductor device exhibited defects, such as delamination and
voids by foaming the adhesive layer. Furthermore, the connection
reliability between the lead of the semiconductor device and the
solder bump was confirmed. In this case, a woven glass-epoxy copper
clad laminate FR-4 (made by Hitachi Chemical Co., Ltd., MCI-E-67)
was used as the mounting substrate. The reliability was evaluated
by performing a thermal cycling test (-55.degree. C..rarw.
.fwdarw.150.degree. C., 1000 times).
EMBODIMENT 2
[0058] A film material having a three layer structure was obtained
by applying an adhesive agent (made by Hitachi Chemical Co. Ltd.,
DF335), composed of a die bonding film material, onto both surfaces
of a polyimide film (made by Ube Kosan Co., Ltd., SGA, 50 .mu.m
thick) to a thickness of 50 .mu.m. The obtained film material was
registered and adhered to circuit tape at 170.degree. C. for five
seconds with a pressure of 30 kgf/cm.sup.2. Under the above
conditions, the unadhered adhesive layer exhibited a sufficient
adhesive force to adhere to the semiconductor element. The circuit
tape attached with the film material was adhered to the
semiconductor element at 200.degree. C. for one minute with a
pressure of 30 kgf/cm.sup.2, and was then post-cured at 200.degree.
C. for 60 minutes in a constant temperature bath. Subsequently,
connecting leads on the circuit tape were electrically connected to
pads of the semiconductor element by gang bonding. The connecting
portion was encapsulated with an epoxy encapsulant (made by Hitachi
Chemical Co., Ltd., RC021C). Finally, the semiconductor device
shown in FIG. 6-2 was obtained by fixing the solder balls, which
served as connecting terminals with the mounting substrate, onto
the circuit tape.
[0059] The reflow characteristics and connection reliability of the
lead and the solder bump of the obtained semiconductor device were
confirmed by the same method as the embodiment 1.
EMBODIMENT 3
[0060] A low elastic adhesive film composed of an epoxy resin and
acrylic rubber (made by Hitachi Chemical Co. Ltd., trial product,
150 .mu.m thick) was registered, placed, and adhered between the
semiconductor element and the circuit tape at 180.degree. C. for 30
seconds with a pressure of 100 kgf/cm.sup.2 , and was then
post-cured at 180.degree. C. for 60 minutes in a constant
temperature bath. Subsequently, connecting leads on the circuit
tape were electrically connected to pads of the semiconductor
element by wire bonding. The connecting portion was encapsulated
with a silicone encapsulant (made by Toshiba Silicone Co., Ltd.,
TSJ 3150) Finally, the semiconductor device shown in FIG. 6-3 was
obtained by fixing the solder balls, which served as connecting
terminals with the mounting substrate, onto the circuit tape.
[0061] The reflow characteristics and connection reliability of the
lead and the solder bump of the obtained semiconductor device were
confirmed by the same method as the embodiment 1.
EMBODIMENT 4
[0062] A film material having a three layer structure was obtained
by adhering a low elastic adhesive film composed of epoxy resin and
acrylic rubber (made by Hitachi Chemical Co. Ltd., trial product,
50 .mu.m thick) to both surfaces of a woven glass-epoxy resin
laminate (obtained by eliminating a copper cladding by etching from
both surfaces of MCL-E-679 made by Hitachi Chemical Co., Ltd.). The
film material was registered, placed, and adhered between the
semiconductor element and the circuit tape at 200.degree. C. for 20
seconds with a pressure of 80 kgf/cm.sup.2, and was then post-cured
at 180.degree. C. for 60 minutes in a constant temperature bath.
Subsequently, connecting leads on the circuit tape were
electrically connected to pads of the semiconductor element by
single point bonding. The connecting portion was encapsulated with
a silicone encapsulant (made by Toshiba Silicone Co., Ltd., TSJ
3153). Finally, the semiconductor device shown in FIG. 8 was
obtained by filing the solder balls, which serve as connecting
terminals with the mounting substrate, onto the circuit tape.
[0063] The reflow characteristics and connection reliability of the
lead and the solder bump of the obtained semiconductor device were
confirmed by the same method as the embodiment 1.
EMBODIMENT 5
[0064] A LOC (Lead on chip) Film (made by Hitachi Chemical Co.
Ltd., HM122U, 100 .mu.m thick) having a three layer structure was
registered and adhered to the circuit tape at 300.degree. C. for 2
seconds with pressure of 150 kgf/cm.sup.2. In the adhering process,
the film was stamped out into a designated shape using the long
scale apparatus shown in FIG. 3, and the stamped film was adhered
to the circuit tape continuously. Because the adhesive layer of the
film was made of a thermoplastic resin, the unadhered portion of
the adhesive layer still had a sufficient adhering force to the
semiconductor element.
[0065] The circuit tape with the film material was adhered to the
semiconductor element at 300.degree. C. for 10 minutes with a
pressure of 100 kgf/cm.sup.2. Subsequently, connecting leads on the
circuit tape were electrically connected to pads of the
semiconductor element by single point bonding. The connecting
portion was encapsulated with an epoxy encapsulant (made by
Hokuriku Toryo Co., Ltd. Chip coat 8107). Finally, the
semiconductor device shown in FIG. 6-1 was obtained by fixing the
solder balls, which served as connecting terminals with the
mounting substrate, onto the circuit tape.
[0066] The reflow characteristics and connection reliability of the
lead and the solder bump of the obtained semiconductor device were
confirmed by the same method as the embodiment 1.
EMBODIMENT 6
[0067] A thermoplastic polyimide film (made by Mitsui Toatsu
Chemicals, Inc., Regulus PI-UAY, 100 .mu.m thick) was registered
and adhered to the semiconductor element at 250.degree. C. for 2
seconds with a pressure of 30 kgf/cm.sup.2. The film had a
sufficient adhesive force to adhere to the circuit tape.
[0068] The semiconductor element with the film material was adhered
to the circuit tape at 250.degree. C. for 10 minutes with a
pressure of 20 kgf/cm.sup.2. Subsequently, connecting leads on the
circuit tape were electrically connected to pads of the
semiconductor element by wire bonding. The connecting portion was
encapsulated with an epoxy encapsulant (made by Hokuriku Toryo Co.,
Ltd. Chip coat 8107). Finally, the semiconductor device shown in
FIG. 6-2 was obtained by fixing the solder balls, which served as
connecting terminals with the mounting substrate, onto the circuit
tape.
[0069] The reflow characteristics and connection reliability of the
lead and the solder bump of the obtained semiconductor device were
confirmed by the same method as the embodiment 1.
EMBODIMENT 7
[0070] A film material composed of a three layer structure having
two different kinds of adhesive layers was obtained by applying a
fluorine-containing polyimide (a reactant of hexafluorobisphenol AF
and bis(4-aminophenoxyphenyl) hexafluoropropane, glass transition
temperature 260.degree. C.) onto one surface of a polyimide film
(made by Ube Kosan Co. Ltd., SGA, 50 .mu.m thick) to a thickness of
50 .mu.m, and a polyetheretherketone (a reactant of
dihydroxy-naphthalene and difluorobenzophenone, glass transition
temperature 154.degree. C.) onto the other surface of the polyimide
film to a thickness of 50 .mu.m.
[0071] The obtained film material was registered and adhered to the
circuit tape using the adhesive layer having a lower glass
transition temperature. The adhesion condition was at 200.degree.
C. for one minute with a pressure of 30 kgf/cm.sup.2. Because the
adhesive layer of the film was composed of a thermoplastic resin,
the adhesive layer had a sufficient adhering force to adhere to the
semiconductor element. The circuit tape with the film material was
adhered to the semiconductor element at 300.degree. C. for ten
seconds with a pressure of 80 kgf/cm.sup.2. Subsequently,
connecting leads on the circuit tape were electrically connected to
pads of the semiconductor element by gang bonding. The connecting
portion was encapsulated with an epoxy encapsulant (made by
Hokuriku Toryo Co. Ltd., Chip coat 8107). Finally, the
semiconductor device shown in FIG. 6-3 was obtained by fixing the
solder balls, which served as connecting terminals with the
mounting substrate, onto the circuit tape.
[0072] The reflow characteristics and connection reliability of the
lead and the solder bump of the obtained semiconductor device were
confirmed by the same method as the embodiment 1.
EMBODIMENT 8
[0073] A silicone adhesive agent (made by Shinetsu Chemical Co.
Ltd., KE1820) was applied onto one surface of a silicone film (made
by Toray Dow Corning Silicone Co. Ltd., JCR6126, 150 .mu.m thick,
press-fabrication) to a thickness of 20 .mu.m. Then, the silicone
film was registered and adhered to the circuit tape. The adhesion
condition was at 150.degree. C. for one minute with a pressure of
30 kgf/cm.sup.2. Furthermore, in order to adhere to the
semiconductor element, the silicone adhesive agent (made by
Shinetsu Chemical Co. Ltd., KE1820) was applied onto the other
surface of the silicone film to a thickness of 20 .mu.m, and the
circuit tape attached with the film material was adhered to the
semiconductor element. The adhesion condition was at 200.degree. C.
for 30 seconds with a pressure of 20 kgf/cm.sup.2. Subsequently,
connecting leads on the circuit tape were electrically connected to
pads of the semiconductor element by gang bonding. The connecting
portion was encapsulated with a silicone encapsulant (made by Toray
Dow Corning Silicone Co. Ltd., DA 6501). Finally, the semiconductor
device shown in FIG. 8 was obtained by fixing the solder balls,
which serve as connecting terminals with the mounting substrate,
onto the circuit tape.
[0074] The reflow characteristics and connection reliability of the
lead and the solder bump of the obtained semiconductor device were
confirmed by the same method as the embodiment 1.
EMBODIMENT 9
[0075] Porous polytetrafluoroethylene (made by Japan Gore-tex Inc.,
190 .mu.m thick), both surfaces of which were applied with BT resin
(Bismaleimide-Triazine resin), was registered and adhered to the
circuit tape. The adhesion condition was at 150.degree. C. for one
minute with a pressure of 30 kgf/cm.sup.2. Because the adhesive
layer of the film was in a B stage condition (half-cured
condition), the adhesive layer had a sufficient adhering force to
adhere to semiconductor element. The adhesion of the circuit tape
with the film material to the semiconductor element was conducted
at 200.degree. C. for 2 minutes with a pressure of 70 kgf/cm.sup.2.
Subsequently, connecting leads on the circuit tape were
electrically connected to pads of the semiconductor element by gang
bonding. The connecting portion was encapsulated with an epoxy
encapsulant (made by Hitachi Chemical Co., Ltd. RO21C). Finally,
the semiconductor device shown in FIG. 6-1 was obtained by fixing
the solder balls, which were connecting terminals with the mounting
substrate, onto the circuit tape.
[0076] The reflow characteristics and connection reliability of the
lead and the solder bump of the obtained semiconductor device were
confirmed by the same method as the embodiment 1.
EMBODIMENT 10
[0077] A sticky tape having a three layer structure (made by
Teraoka Seisakusyo, Ltd., Tape No. 760, 145 .mu.m thick, silicone
adhesive agent was applied onto both surfaces of Kapton film
(commercial name by Du Pont)) was registered and adhered to the
circuit tape at room temperature for 5 seconds with a pressure of
50 kgf/cm.sup.2. In the adhering process, the film was stamped out
into a designated shape using the long scale apparatus shown in
FIG. 3, and the stamped film was adhered to the circuit tape
continuously. Because the adhesive layer of the film was made of a
sticky resin, the unadhered portion of the adhesive layer still had
a sufficient adhering force to adhere to the semiconductor
element.
[0078] The circuit tape with the film material was adhered to the
semiconductor element at room temperature for 10 seconds with a
pressure of 5 kgf/cm.sup.2. Subsequently, connecting leads on the
circuit tape were electrically connected to pads of the
semiconductor element by single point bonding. The connecting
portion was encapsulated with a silicone encapsulant (made by
Toshiba Silicone Co. Ltd. TSJ 3150). Finally, the semiconductor
device shown in FIG. 6-2 was obtained by fixing the solder balls,
which serve as connecting terminals with the mounting substrate,
onto the circuit tape.
[0079] The reflow characteristics and connection reliability of the
lead and the solder bump of the obtained semiconductor device were
confirmed by the same method as the embodiment 1.
EMBODIMENT 11
[0080] A cohesive tape having a three layer structure (150 .mu.m
thick, butadiene adhesive agent was applied onto both surfaces of
unwoven aramide cloth (100 .mu.m thick)) was registered and adhered
between semiconductor and circuit tape at room temperature for 5
seconds with a pressure of 50 kgf/cm.sup.2. Under the above
condition, some correction of the registration was possible,
because the adhesive layer was still in a cohesive condition. Then,
the adhesive layer of the film was cured at 180.degree. C. for 60
minutes in a constant temperature bath to form a connecting state
having a three dimensional crosslinking structure, because the
adhesive layer was made of a cohesive resin.
[0081] Subsequently, connecting leads on the circuit tape were
electrically connected to pads of the semiconductor element by
single point bonding. The connecting portion was encapsulated with
a silicone encapsulant (made by Toshiba Silicone Co., Ltd. TSJ
3150). Finally, the semiconductor device shown in FIG. 6-3 was
obtained by fixing the solder balls, which serve as connecting
terminals with the mounting substrate, onto the circuit tape.
[0082] The reflow characteristics and connection reliability of the
lead and the solder bump of the obtained semiconductor device were
confirmed by the same method as the embodiment 1.
EMBODIMENT 12
[0083] A polyamic acid was prepared by reacting an equivalent of
benzophenone tetracarboxylic acid dianhydride (made by Wako Pure
Chemicals) and bis(4(2-aminophenoxyphenyl)ether) (synthetic
chemical) at 5.degree. C. in dimethylacetamide. Then, the reactant
was heated at 250.degree. C. to obtain polyimide. The obtained
polyimide 100 g was mixed with 4,4'-glycidyl-3,3',
5,5'-tetramethylbiphenylether (made by Yuka Shell) 19.5 g phenol
novolac (made by Meiwa Kasei) 10.6 g, and triphenyliphosphate (made
by Wako Pure Chemicals) 0.2 g as a catalyst in dimethylacetamide to
obtain a varnish containing a non-volatile component of 20% by
weight. A film 100 .mu.m thick was prepared with the obtained
varnish.
[0084] The prepared film was registered and adhered to the circuit
tape. The adhesion condition was at 170.degree. C. for ten seconds
with a pressure of 30 kgf/cm.sup.2. Under the above conditions, the
unadhered portion of the adhesive layer had a sufficient adhering
force to adhere with semiconductor element. The adhesion of the
circuit tape with the film material to the semiconductor element
was conducted at 200.degree. C. for one minute with a pressure of
30 kgf/cm.sup.2. Subsequently, a post-curing was performed at
200.degree. C. for 60 minutes in a constant temperature bath. Then,
connecting leads on the circuit tape were electrically connected to
pads of the semiconductor element by gang bonding. The connecting
portion was encapsulated with an epoxy encapsulant (made by Hitachi
Chemical Co., Ltd. RC021C). Finally, the semiconductor device shown
in FIG. 6-2 was obtained by fixing the solder balls, which serve as
connecting terminals with the mounting substrate, onto the circuit
tape.
[0085] The reflow characteristics and connection reliability of the
lead and the solder bump of the obtained semiconductor device were
confirmed by the same method as the embodiment 1.
EMBODIMENT 13
[0086] A film having a three layer structure was prepared by
applying the varnish obtained in the embodiment 12 onto the one
surface of polyimide film (made by Ube Kosan Co. Ltd., SGA, 50
.mu.m thick) to a thickness of 20 .mu.m (thermosetting resin
component), and the fluorine-containing polyimide, i.e. the varnish
prepared in the embodiment 7, (the reactant of hexafluorobisphenol
AF and bis(4-aminophenoxyphenyl) hexafluoropropane, with a glass
transition temperature of 260.degree. C.) was applied onto the
other surface of the polyimide film to a thickness of 10 .mu.m
(thermoplastic resin component). The film was registered and
adhered to the circuit tape at the surface where the thermosetting
resin component was applied. The adhesion condition was at
170.degree. C. for 10 seconds with a pressure of 30 kgf/cm.sup.2.
Then, a post-curing was performed at 200.degree. C. for 60 minutes
in a constant temperature bath. Subsequently, the semiconductor
element was adhered to the surface where the thermoplastic resin
component was applied. The adhesion condition was at 350.degree. C.
for 2 seconds with a pressure of 80 kgf/cm.sup.2. Then, connecting
leads on the circuit tape were electrically connected to pads of
the semiconductor element by gang bonding. The connecting portion
was encapsulated with an epoxy encapsulant (made by Hokuriku Toryo
chip coat 8107). Finally, the semiconductor device shown in FIG.
6-2 was obtained by fixing the solder balls, which serve as
connecting terminals with the mounting substrate, onto the circuit
tape.
[0087] The reflow characteristics and connection reliability of the
lead and the solder bump of the obtained semiconductor device were
confirmed by the same method as the embodiment 1.
COMPARATIVE EXAMPLE 1
[0088] An elastomer of 150 .mu.m thickness was formed by
registering silicone resin (made by Toray Dow Corning Silicone Co.
Ltd., JCR 6126) with the circuit tape and printing using metal
masks. After the formation, post-curing was performed at
150.degree. C. for 60 minutes in a constant temperature bath. Then,
the flatness of the elastomer was determined using a laser film
thickness measuring apparatus. A silicone adhesive agent (made by
Sinetsu Chemical Co. Ltd., KE 1820) was applied onto the surface of
the elastomer a thickness of 20 .mu.m as an adhesive layer for
causing the semiconductor element to adhere to the circuit tape
having the elastomer, and the circuit tape was registered and
adhered to the semiconductor element. The adhesion was carried out
at 150.degree. C. for one minute with a pressure of 30
kgf/cm.sup.2. Then, connecting leads on the circuit tape were
electrically connected to pads of the semiconductor element by gang
bonding. The connecting portion was encapsulated with a silicone
encapsulant (made by Toshiba Silicone, TSJ 3150). Finally, the
semiconductor device shown in FIG. 6-1 was obtained by fixing the
solder balls, which serve as connecting terminals with the mounting
substrate, onto the circuit tape.
[0089] The reflow characteristics and connection reliability of the
lead and the solder bump of the obtained semiconductor device were
confirmed by the same method as the embodiment 1.
COMPARATIVE EXAMPLE 2
[0090] A film having a three layer structure was prepared by
applying a thermoplastic resin (polyamide 12, m.p. 175.degree. C.)
having a melting point equal to or lower than 200.degree. C. onto
both surfaces of a polyimide film (made by Ube Kosan Co.
[0091] Ltd., SGA, 50 .mu.m thick) as adhesive layers (30 .mu.m
thick). The film having the three layer structure was used to
prepare a semiconductor device using the same method as the
embodiment 1, and the reflow characteristics and connection
reliability of the lead and the solder bump of the obtained
semiconductor device were confirmed by the same method as the
embodiment 1.
COMPARATIVE EXAMPLE 3
[0092] A film having a three layer structure was prepared by
applying an epoxy resin (made by Hitachi Chemical Co., Ltd., RO21C)
having a high modulus of elasticity at room temperature onto both
surfaces of a polyimide film (made by Ube Kosan Co. Ltd., SGA) as
adhesive layers (20 .mu.m thick). The film having the three layer
structure was used to prepare a semiconductor device by the same
method as the embodiment 1, and the reflow characteristics and
connection reliability of the lead and the solder bump of the
obtained semiconductor device were confirmed by the same method as
the embodiment 1.
1 TABLE 1 Elastic modulus (MPa) Adhesive Thermal cycling layers
test(1000 cycles) Adhesive (average Lead open Bump open film of
200.about. Reflow failure failure (25.degree. C.) 250.degree. C.)
test (%) (%) Emb.* 1 788 4.3 No void 0 0 Emb. 2 5000 1.5 No void 0
0 Emb. 3 960 3.6 No void 0 0 Emb. 4 4190 3.6 No void 0 0 Emb. 5
3750 13 No void 0 0 Emb. 6 3500 100 No void 0 0 Emb. 7 3500 2000,
15 No void 0 0 Emb 8 10 2.5 No void 0 0 Emb. 9 2000 100 No void 0 0
Emb. 10 20 2.5 No void 0 0 Emb. 11 30 3.5 No void 0 0 Emb. 12 850
8.5 No void 0 0 Emb. 13 3300 2000, 8.5 No void 0 0 Com.1 10 2.5 No
void 10 0 Com. 2 1400 .about.0 Void 5 0 Com. 3 11000 1100 No void
80 100 *: Embodiment, : Comparative example.
[0093] Flatness of the elastomer: High and low difference of
comparative example 1 was 50 .mu.m to thickness of 150 .mu.m, and
all other samples within 5.mu.m.
[0094] Reflow test condition: Pretreatment: 85.degree. C./85% RH,
48 hours, Water absorption 240.degree. C..times.3 times, Infrared
oven.
[0095] In accordance with the present invention, a semiconductor
device is provided, wherein tape material having a circuit layer
and a semiconductor element are electrically connected, an external
terminal for effecting electrical connection with the mounting
substrate is provided on the circuit tape, and a film material is
used as the material for bonding the circuit tape and the
semiconductor element in an insulating manner, resulting in a
semiconductor device which is superior in anti-reflow property due
to the use of the film material for the adhesion, of which the
modulus of elasticity in the reflow temperature range is at least 1
MPa. A manufacturing method is also provided which is superior in
mass productivity by using a film material at a portion for
buffering thermal stress generated by a difference in thermal
expansion of the semiconductor element and the mounting
substrate.
[0096] The film material is superior in flatness, and a high and
low difference within 5 .mu.m can be ensured for a thickness of 150
.mu.m, and so a manufacturing method which is superior in
workability can be provided. In accordance with the stress
buffering effect of the film material, the connection reliability
of both the lead portion which electrically connects the circuit
tape and the semiconductor element, and the bump which electrically
connects the semiconductor device and the mounting substrate can be
satisfied simultaneously in a temperature cycling test.
* * * * *