Adhesive polyimide siloxane composition employable for combining electronic parts

An adhesive polyimide composition comprises 100 weight parts of a polyimide siloxane having a Tg of not lower than 200.degree. C. and 0.2 to 5 weight parts of a silane coupling agent having a glycidyl group. An epoxy resin may be incorporated into the polyimide composition. The polyimide siloxane is prepared by polymerization reaction of an aromatic tetracarboxylic acid dianhydride or its derivative and a diamine composition comprising 5 to 25 mol. % of a specific diaminosiloxane and 75 to 95 mol. % of an aromatic diamine having at least two benzene rings and one oxygen atom intervening these benzene rings. The adhesive polyimide composition is generally employed in the form of a solution in an organic solvent and for combining electrically conductive or insulating members.

FIEND OF THE INVENTION 
The present invention relates to an adhesive polyimide composition and an 
adhesive composite comprising a substrate and an adhesive polyimide layer. 
More particularly, the invention relates to an adhesive polyimide 
composition favorably employable for combining electronic parts such as of 
silicon, metal, and heat-resistant plastic material. 
BACKGROUND OF THE INVENTION 
Recently, the function and capacity of semiconductor chips are increased 
and their sizes are enlarged. Nevertheless, it is desired to keep or even 
reduce the sizes of electronic devices. Under the circumstances, new 
designs for more densely arranging semiconductor chips have been proposed. 
One representative design is called LOC (lead-on-chip) structure for 
manufacturing memory element which comprises fixing a chip on a lead frame 
equipped with no die pad using a double sided adhesive tape. As for logic 
element, there is proposed a multi-layered lead frame structure in which 
an electric source and ground are mounted on a separate frame and a metal 
plate is multi-layered for heat radiation. By utilizing these structures 
of new design, reduction of the element size can be accomplished because 
these structures enable to make wiring within chip, simplification of wire 
bonding, enhancement of signal transfer rate by shortened wiring, and heat 
radiation of high efficiency. The heat radiation of high efficiency is 
required to cope with increase of heat produced by increased electric 
power consumption. 
In these new structures, a variety of elements of different materials 
should be bonded to each other. For instance, bonding between a 
semiconductor chip and a lead frame, bonding between a lead frame and a 
plate, bonding of two lead frames to each other, and so on are required. 
Naturally these bondings directly effect reliability of the obtained 
element. The bondings should be kept reliably not only in the procedures 
for manufacture of the element but also in the course of practical use of 
the produced element. In these procedures and courses, the element 
encounters various heat and humidity conditions. Further, the bonding 
should be performed with no high skill. 
The bonding of these members and parts is performed using an adhesive in 
the form of paste. The adhesive is sometimes coated on a heat-resistant 
substrate. Heretofore, heat curable adhesives such as of epoxy type, 
acrylic resin type and rubber-phenol resin type have been employed for the 
bonding. However, these known heat curable adhesives have certain 
disadvantageous features such as inherently contaminated ionic impurity, 
low productivity due to requirement of high temperature and long period of 
time for curing the resin, production of large amount of volatile 
materials in the curing procedure which stain the lead members, and high 
moisture absorption. These features are unfavorable in view of the recent 
requirement for adhesive enabling bonding of high reliability. 
A number of proposals for employing heat-resistant heat contact pressure 
adhesives in the form of a film in place of the heat curable adhesives. 
For instance, Japanese Patent Provisional Publication (unexamined 
publication) No. H 1-282283 discloses hot melt adhesives of polyamideimide 
type and polyamide type. Japanese Patent Provisional Publication (JPPP) 
Sho 58-157190 discloses a process for manufacturing flexible 
circuit-printable substrate utilizing a polyimide adhesive. Japanese 
Patent Provisional Publications No. Sho 62-235382, No. Sho 62-235383, and 
No. H 2-15663 all describe heat curable polyimide adhesive in the form of 
film. 
Japanese Patent Provisional Publication (JPPP) No. Sho 51-63881 describes a 
composite of a heat-resistant film and a metal foil which is bonded by a 
heat resistant adhesive comprising a polyamideimide resin and an epoxy 
resin. 
JPPP No. Sho 59-197479 describes a curable composition comprising polyamic 
acid and an epoxy resin precursor. 
JPPP No. Sho 62-243673 describes a heat curable (or thermosetting) 
polyimide adhesive comprising an epoxy resin, a polyimide resin soluble in 
an organic solvent, a reaction solvent and a cross-linking agent. 
JPPP No. Sho 64-69667 (corresponding to U.S. application Ser. No. 088,142) 
describes a polyimide coating composition comprising a simple polyimide, 
an aminosilane compound and a neutral solvent. 
JPPP No. H 1-282283 describes a hot melt adhesive comprising a 
polyamideimide compound which employs a diamine component having three 
benzene rings. 
JPPP No. H 2-15663 describes an adhesive tape for lead frame which 
comprises a polyimide film having a semi-cured polyimide type LARC 
adhesive on both sides thereof. 
JPPP No. H 5-332443 describes an adhesive film which is prepared by drying 
a composition comprising a silicone-modified polyimide, a cross-linking 
agent (aromatic polyamine or polycarboxylic acid), and a solvent. 
JPPP No. H 5-331445 describes an adhesive film which is obtained from a 
solution of a polyimide resin in an organic solvent having a boiling point 
of not higher than 180.degree. C., in which the polyimide resin employs 
.alpha.,.omega.-bisaminopolydimethylsiloxane as a portion of its diamine 
component. 
JPPP No. H 6-45736 describes a heat curable film comprising an aromatic 
polyimide having a specific formula. 
JPPP No. H 6-172713, No. H 6-172714, and No. H 6-172736 describe an 
adhesive film comprising a polyimide resin soluble in an organic solvent 
which is prepared from a tetracarboxylic acid dianhydride, an aromatic 
diamine and diamino siloxane. 
The polyamide and polyamideimide resins disclosed in the above publications 
have relatively high water absorption due to the presence of a hydrophilic 
amide group in their molecular structure. Therefore, these resins are not 
appropriate as the use of adhesives for electronic devices which require 
extremely high production reliability. 
The polyimide adhesive which is modified to become heat curable requires a 
curing condition such as 30 minutes at 275.degree. C., 50 kg/cm.sup.2, or 
requires a pre-treatment to have a semi-cured condition and then a long 
curing time. The long curing time required is naturally disadvantageous 
for production of electronic devices in a large scale. Moreover, a 
condensation water is produced in the curing procedure, which is 
undesirable for inclusion into electronic devices which are sensitive to 
heat, pressure, and water. 
An ordinary polyimide resin which is neither heat curable nor thermoplastic 
is known to have high heat resistance, non-flammability, and high electric 
insulation. Therefore, the polyimide resin is employed as material for 
inclusion into electronic devices. However, the polyimide shows a certain 
water absorption. Moreover, the polyimide cannot be easily processed 
because it has an extremely high melting temperature or cannot be melted 
and is not soluble in most of organic solvents. Therefore, when the 
polyimide resin is employed as material for producing insulative 
intervening layer or surface coating layer of a semiconductor device, the 
polyimide resin is not directly employed, but a precursor of polyimide, 
that is, a polyamic acid (which is soluble in amide type solvents) is 
coated on a member of semiconductor and heated to remove the solvent and 
to give an imide group. Since the amide type solvent has a high boiling 
point, a long period of time and a high temperature are required for 
complete removal of the solvent. Further, in the course of removal of the 
high boiling point amide solvent, bubbles may be produced in the polyimide 
layer to be prepared. Moreover, such long time treatment at a high 
temperature sometimes causes deterioration of the resulting semiconductor 
product. 
Accordingly, almost all of the polyamide, polyamideimide and polyimide 
compositions described in the above-mentioned publications have certain 
unfavorable features, such as, high water absorption, poor adhesion, 
particularly, to a polyimide film, low solubility in an organic solvent of 
a low boiling temperature, or the like. 
SUMMARY OF THE INVENTION 
Accordingly, the present invention has an object to provide an adhesive 
polyimide composition which shows easy adhesion within a relatively short 
time at a temperature of 250.degree. to 300.degree. C., and has a high 
heat resistance, a low water absorption and a satisfactory solubility in 
organic solvents having a low boiling point such as tetrahydrofuran (THF), 
1,4-dioxane and ethylene glycol dimethyl ether. 
The present invention resides in an adhesive polyimide composition 
comprising: 
100 weight parts of a polyimide siloxane having a glass transition 
temperature of not lower than 200.degree. C., said polyimide siloxane 
being prepared from an aromatic tetracarboxylic acid dianhydride or its 
derivative and a diamine composition comprising 5 to 25 mol. % of a 
diaminosiloxane having the formula (I): 
##STR1## 
wherein R is a divalent hydrocarbon residue, each of R.sup.1, R.sup.2, 
R.sup.3, and R.sup.4 independently is a lower alkyl group or phenyl, and k 
is an integer of 0 to 30, and 75 to 95 mol. % of an aromatic diamine 
having the formula (II): 
EQU H.sub.2 N--R.sup.5 --NH.sub.2 (II) 
wherein R.sup.5 represents one of the formulas of --Bz--O--Bz-- and 
--Bz--O--X--O--Bz--, wherein Bz means a benzene ring and X represents 
--Bz-- or --Bz--Y--Bz--, wherein Y is SO.sub.2, O, CH.sub.2 or 
C(CH.sub.3).sub.2, and 
0.2 to 5 weight parts of a silane coupling agent having a glycidyl group. 
DETAILED DESCRIPTION OF THE INVENTION 
The adhesive polyimide composition of the invention preferably comprises 
further 0.1 to 30 weight parts of an epoxy resin. The aromatic 
tetracarboxylic acid dianhydride or its derivative preferably is 
2,3,3',4'-biphenyltetracarboxylic acid dianhydride or its derivative. The 
adhesive polyimide composition of the invention preferably has a water 
absorption not more than 1 wt. % and is preferably used in the form of a 
film. 
In the preparation of the adhesive polyimide composition film of the 
invention, the polyimide is employed in the form of a solution which 
comprises 100 weight parts of the polyimide siloxane and the silane 
coupling agent in an organic solvent. 
The adhesive polyimide composition of the invention can be employed for the 
formation of an adhesive composite comprising a substrate such as of 
silicon, metal and heat-resistant plastic material, and an adhesive layer 
of the polyimide composition of the invention. The adhesive composite can 
be prepared by a process comprising the steps of coating a solution of the 
polyimide composition in an organic solvent on the substrate to give a 
coated layer, and drying the coated layer to remove the solvent. 
The above adhesive composite can be utilized to give a composite comprising 
two substrates and an adhesive polyimide composition layer intervening 
between these substrates, in which one substrate is an aromatic polyimide 
film and another substrate is material selected from the group consisting 
of an aromatic polyimide film, a silicon plate, a copper film, or a 
polyimide siloxane film and the adhesive polyimide composition layer is 
made of the adhesive polyimide composition of the invention and has a 
water absorption of not more than 1 wt. %. 
The adhesive polyimide composition is industrially advantageous because it 
can be employed for combining a film of an aromatic polyimide prepared 
from 3,3',4,4'-biphenyltetracarboxylic acid anhydride and p-phenylene 
diamine with the same polyimide film or other substrate materials such as 
metal plate, silicon wafer and films of other heat-resistant plastic film. 
These materials can be easily combined by the adhesive polyimide 
composition of the invention without surface activating treatment. 
The aromatic tetracarboxylic acid dianhydride or its derivatives is 
preferred to be 2,3,3',4'-biphenyltetracarboxylic acid dianhydride or its 
derivatives such as its free acid and esters. The dianhydride is most 
preferred. Other examples of the aromatic tetracarboxylic acids for the 
dianhydride and its derivatives include 3,3',4,4'-biphenyl tetracarboxylic 
acid, 3,3',4,4'-benzophenonetetracarboxylic acid, 
3,3',4,4'-diphenylethertetracarboxylic acid, 
bis(3,4-dicarboxyphenyl)methane, 2,2-bis(3,4-dicarboxyphenyl)propane, and 
pyromellitic acid. The aromatic tetracarboxylic acid dianhydride or its 
derivatives preferably contains not less than 75 mol. % of 2,3,3', 
4'-biphenyltetracarboxylic acid dianhydride. 
In the diaminosiloxane of the formula (I), R preferably has 2 to 6 carbon 
atoms, and preferably is 3 to 5 methylene group or a phenylene group. Each 
of R.sup.1, R.sup.2, R.sup.3 and R.sup.4 preferably is a lower alkyl group 
having 1 to 5 carbon atoms (e.g., methyl, ethyl, or propyl) or a phenyl 
group. "k" preferably is an integer of 1 to 20, more preferably is an 
integer of 3 to 15. These groups and numbers are appropriate in view of 
its reactivity and the characteristics such as heat resistance of the 
resulting polyimide siloxane. The diaminosiloxane is used in an amount 
corresponding to 5 to 25 mol. % of the diamine component to be employed 
for the preparation of the polyimide siloxane. The amount is appropriate 
in view of the solubility and heat resistance of the resulting polyimide 
siloxane. 
Examples of the diaminosiloxane of the formula (I) include 
.omega.,.omega.'-bis(2-aminoethyl)polydimethylsiloxane, 
.omega.,.omega.'-bis(3 -aminopropyl) polydimethylsiloxane, 
.omega.,.omega.'-bis(3-aminobutyl)polydimethylsiloxane, 
.omega.,.omega.'-bis(4-aminophenyl)polydimethylsiloxane, 
.omega.,.omega.'-bis(4-amino-3-methylphenyl)polydimethylsiloxane, 
.omega.,.omega.'-bis(3-aminopropyl)polydimethylsiloxane, and 
bis(aminopropyldimethylsilyl)benzene. 
At least 75 mol. % of the diamine component to be employed for the 
preparation of the polyimide siloxane should be the aromatic diamine of 
the formula (II). If the aromatic diamine has only one aromatic ring, the 
resulting polyimide siloxane would have poor solubility in a low boiling 
point solvent such as tetrahydrofuran. Diamine components other than 
aromatic diamine are not appropriate from the viewpoint of heat 
resistance. 
Examples of the aromatic diamine of the formula (II) include 
1,4-bis(3-aminophenoxy)benzene (1,4,3-APB), 1,3-bis(3-aminophenoxy)benzene 
(1,3,3-APB), 1,3-bis(4-aminophenoxy)benzene (1,3,4-APB), 
2,2-bis4-(4-aminophenoxy)phenyl!propane (BAPP), 4,4'-diaminodiphenylether 
(4,4'-DDE), 3,3'-diaminodiphenylether, 3,4'-diaminodiphenylether, 
4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 2,2-bis 
(4-aminophenyl)hexafluoropropane, 
2,2-bis4-(4-aminophenoxy)phenyl!hexafluoropropane, 
bis-4-(4-aminophenoxy)phenylsulfone, bis-4-(3-aminophenoxy)phenylsulfone, 
and 4,4'-diaminodiphenylmethane. 
The aromatic tetracarboxylic acid dianhydride or its derivative and the 
diamine component are preferably used in a ratio of equivalent (i.e., 
equivalent of total carboxylic acid component/equivalent of total 
diamine=r) under the condition of 0.900.ltoreq.r.ltoreq.1.08. If "r" is 
too low or high, the resulting polymer likely has a relatively low 
molecular weight and shows a relatively low heat resistance. Further, if 
"r" is too high, unreacted carboxylic acid is apt to decompose under 
heating to produce a gas in the coated layer. r=1 is most preferred. 
The reaction between the aromatic tetracarboxylic acid dianhydride or its 
derivative and the diamine can be performed in an aprotic (i.e., 
non-protonic) polar solvent according to the known methods. The aprotic 
polar solvent may be N,N-dimethylformamide (DMF), N,N-dimethylacetamide 
(DMAc), N-methyl-2-pyrrolidone (NMP), tetrahydrofuran (THF), diethylene 
glycol dimethyl ether (diglyme), cyclohexanone, or 1,4-dioxane. The 
aprotic solvent can be employed singly or in combination with each other. 
The aprotic solvent also can be employed in combination with a compatible 
non-polar solvent such as an aromatic hydrocarbon (e.g., toluene, xylene 
or solvent naphtha). The non-polar solvent in the reaction solvent should 
be less than 30 wt. % of the total solvent. If the reaction solvent 
contains too much non-polar solvent, a polyamic acid produced by the 
reaction likely precipitates from the reaction solution. 
The reaction between the aromatic tetracarboxylic acid dianhydride or its 
derivative with the diamine component is preferably carried out by placing 
a sufficiently dried diamine component in the reaction solvent to give a 
solution and then placing a sufficiently dried aromatic tetracarboxylic 
acid component (dianhydride or its derivatives) of a ring closure ratio of 
not less than 98%, preferably not less than 99%. The resulting polyamic 
acid solution is heated in the reaction solution to perform dehydration 
and ring closing reaction for imidization, yielding a polyimide siloxane. 
Water produced in the course of the imidization reaction disturbs the ring 
closing reaction. Therefore, the water is removed in the presence of a 
water-incompatible organic solvent by azeotropic distillation through a 
Dean-Stark tube or the like. The aforementioned aromatic hydrocarbons can 
be employed as the water-incompatible organic solvent. In the imidization 
reaction, a catalyst such as acetic anhydride, .beta.-picoline, or 
pyridine may be employed. 
The resulting polyimide siloxane preferably has a molecular weight (Mn) in 
the range of 5,000 to 50,000, and a logarithmic viscosity of 0.2 to 1.5. 
The polyimide siloxane preferably has a ring closure ratio as high as 
possible, preferably not less than 95%, more preferably not less than 98%. 
If the ring closure ratio is too low, water is produced in the course of 
bonding procedure by imidization. The reaction mixture containing the 
resulting polyimide siloxane can be as such (or after adjusting the 
concentration of the polyimide siloxane) employed as a liquid adhesive 
composition. It is preferred, however, that the polyimide siloxane is 
precipitated and recovered from the reaction mixture by pouring the 
reaction mixture into a poor solvent. By this procedure, unreacted monomer 
and other impurities are removed, and the polyimide siloxane is purified. 
The silane coupling agent having a glycidyl group preferably is heat 
resistant and has a boiling point of not lower than 250.degree. C. 
Preferred examples of the silane coupling agent include 
.gamma.-glycidoxypropyltrimethoxysilane, and 
.gamma.-glycidoxypropylmethyldiethoxysilane. The silane coupling agent 
preferably has no amino group in the molecular structure. The silane 
coupling agent is employed in an amount of 0.2 to 5 weight parts, per 100 
weight parts of the polyimide siloxane, from the viewpoint of adhesion at 
an elevated temperature. If the amount of the silane coupling agent is 
less than the above range, satisfactory adhesion is not accomplished. Use 
of the silane coupling agent in an amount of more than the upper limit is 
not economical, because the adhesion strength no more increases. Moreover, 
too much silane coupling agent makes the adhesive layer too plastic and 
imparts adverse effect to the adhesive later when it is heated at an 
elevated temperature. 
The epoxy resin preferably has two epoxy group in one molecular unit and 
preferably is a bisphenol-A epoxy resin or a bisphenol-F epoxy resin. The 
epoxy resin preferably has a melting point of not higher than 90.degree. 
C., such as a melting point of 0.degree. to 80.degree. C. Particularly 
preferred epoxy resin is liquid at room temperature (23.degree. C.). The 
epoxy resin is generally used not more than 30 weight parts, preferably 
0.1 to 30 weight parts, more preferably 0.2 to 15 weight parts, per 100 
weight parts of the polyimide siloxane, from the viewpoint of workability, 
particularly imparting to the adhesive composition sufficient flowability 
at an elevated temperature. 
The adhesive polyimide composition of the invention can be made in the form 
of a film or tape for binding or combining electronic parts by dissolving 
the polyimide composition in an appropriate organic solvent such as 
tetrahydrofuran to give an adhesive polyimide composition solution, 
coating the solution on a substrate and then drying the coated solution. 
Therefore, the adhesive polyimide composition is preferably employed in the 
form of a solution in an organic solvent. In the solution, the content (or 
concentration) of the adhesive polyimide composition preferably is in the 
range of 10 to 45 wt. %, more preferably in the range of 15 to 40 wt. %. 
Most preferred content is between 20 and 30 wt. %. An adhesive polyimide 
composition solution having a concentration of lower than 10 wt. % is 
disadvantageous for preparing an adhesive film of a satisfactory 
thickness. An adhesive polyimide composition solution having a too much 
concentration is also disadvantageous because its production requires a 
long time and its viscosity is too high to give a uniform adhesive layer 
with no air bubbles. 
The organic solvent for the preparation of the adhesive polyimide 
composition solution preferably has a boiling point of not higher than 
160.degree. C., from the viewpoint of workability and cost. Preferred are 
tetrahydrofuran (b.p.: 66.degree. C.), 1,4-dioxane (b.p.: 101.degree. C.), 
and ethylene glycol dimethyl ether (monoglyme, b.p.: 84.degree. C.). 
The adhesive polyimide composition solution can be coated and dried on a 
substrate using a known coating apparatus such as a combination of a flow 
coater or a roll coater and a hot-air dryer. In more detail, the substrate 
coated with the solution is introduced into a hot-air dryer to dry the 
coated solution at a temperature for evaporating the solvent, preferably 
at a temperature of 60.degree. to 200.degree. C. The dried solution layer 
can be peeled off the substrate. The substrate can be a metal foil or 
plate of stainless, aluminum or copper, a silicon plate such as silicon 
wafer, a heat resistant plastic film such as an aromatic polyimide film 
and a polyester film, particularly, a film of an aromatic polyimide which 
is prepared from an aromatic tetracarboxylic acid component comprising 
3,3',4,4'-biphenyltetracarboxylic acid dianhydride and an aromatic diamine 
component. Until now, there is not known a heat resistant adhesive 
composition for binding the aromatic polyimide film of this type with 
other material at a satisfactorily high strength. 
The substrate having the coated and dried adhesive polyimide composition 
solution can be employed as such for receiving another substrate on the 
adhesive polyimide composition layer. The adhesive polyimide composition 
of the invention is also employable for preparing a multi-layered 
composite comprising three or more substrate or related materials. 
The adhesive polyimide composition film can be cut to a chip or strip of an 
appropriate size, placed on an appropriate substrate such as a ceramic 
member, silicon wafer, copper foil, aluminum foil, gold foil, a heat 
resistant polyimide film such as that mentioned above, and heated thereon 
using a hot heat block. The adhesive polyimide composition solution can be 
coated and dried on a member of electronic parts, and other member is 
placed on the dry layer. These composite is then heated for fixing the 
other member on the former member. 
The present invention is further described by the following non-limitative 
examples. In the examples, "part(s)" means "part(s) by weight", unless 
otherwise indicated. 
The molecular weight of the polymer was determined using a commercially 
available MLC-8020 (by Toso Co., Ltd.) and preparing a calibration curve 
in advance by use of a monodispersed polystyrene. Accordingly, the 
molecular weight is indicated in terms of a polystyrene-converted 
molecular weight. Other measurements were carried out in the following 
manner. 
(1) Characteristics of polyimide siloxane and adhesive composition sheet 
______________________________________ 
TGA: TGA-50 (commercially available from Shimazu 
Seisakusho Co., Ltd.) 
Measurement conditions: 
Temperature elevation: 5.degree. C./min. 
Temperature range: Room temperature to 600.degree. C. 
Circumferential conditions: in air, 30 mL/min. 
Adhesion strength: 
A pair of specimen of Fe-Ni alloy (42 alloy) of 
25 .mu.m thick which was previously washed with acetone 
were employed. The adhesion strength (at 180.degree. peel- 
ing) was measured in a tensile strength tester (Type 
200 available from Intesco Corp.) at a peeling rate 
of 50 mm/min. at 25.degree. C. 
Dynamic viscoelasticity: 
Viscoelasticity analyzer RSA II (available from 
Leometrix Corp.) 
Sample: Film of 5 mm (width) .times. 22 mm (length) 
Measurement conditions: 
Tests: Tension - Compression 
Mode: Dynamic 
Steep type: Temperature step 3.degree. C. 
Retention 30 sec. 
Strain (%): 0.05% 
Frequency: 1.0 Hz 
Temperature range: -150.degree. C. to upper measurement 
limit 
Logarithmic viscosity (.eta..sub.inh): 
The polymer was dissolved in N-methyl-2- 
pyrrolidone to give a polymer solution of 0.5 g/100 mL 
and its viscosity was measured at 30.degree. C. Simultaneously, a 
viscosity of the solvent used was measured at the same 
temperature. The viscosity values were treated as fol- 
lows: 
Logarithmic viscosity (ln) = 
(Viscosity.sub.solution /viscosity.sub.solvent)/Concentration.sub.sol 
ution 
Mn: calculated from the polystyrene converted molecular 
weight 
______________________________________

EXAMPLE 1 
In 500 mL-volume glass flask equipped with a thermometer, an inlet-outlet 
and a stirrer were placed 26.48 parts (90 mmol.) of 
2,3,3'4'-biphenyltetracarboxylic acid dianhydride (a-BPDA), 16.8 parts (20 
mmol.) of .omega.,.omega.'-bis(3-aminopropyl)polydimethylsiloxane (BAPS) 
(X-22-161 AS k=8, available from Shin-Etsu Silicon Co., Ltd.), and 300 
parts of N-methyl-2-pyrrolidone (NMP). The mixture was heated to 
50.degree. C. in the stream of a nitrogen gas to prepare a solution. To 
the solution were added 28.74 parts (70 mmol.) of 
2,2-bis4-(4-diaminophenoxy)phenyl!-propane (BAPP). The mixture was then 
stirred at the same temperature for one hour. To the resulting solution 
was further added 50 parts of xylene, and the mixture was heated to 
200.degree. C. The mixture was then refluxed under stirring for 3 hours 
with distilling off the produced water, to obtain a homogeneous polymer 
solution containing 18 wt. % of polyimide siloxane. 
The polymer solution was left to reach room temperature, and filtered under 
pressure. The filtrate was mixed with an ion-exchanged water to 
precipitate the polyimide siloxane. A purified polyimide siloxane was then 
recovered after washing and drying at 250.degree. C. for 5 hours. Yield: 
54 parts (95%), Imidization ratio: approximately 100%, logarithmic 
viscosity: 0.52). By measuring GPC of the obtained polyimide siloxane, it 
was determined that the number average molecular weight (Mn) was 15,600, 
and weight average molecular weight (Mw) was 59,500. The polyimide 
siloxane was then subjected to thermogravimetry to give its heat 
decomposition starting temperature of 418.degree. C. The measurement of 
dynamic viscoelasticity (in terms of tan .delta.) using a viscoelasticity 
analyzer RSA II (available from Leometrix Corp.) indicated that Tg was 
234.degree. C. 
In a 500 mL-volume glass flask were placed 100 parts of the above-obtained 
polyimide siloxane, 5 parts of two functional epoxy compound (Ep 807, 
liquid, available from Yuka-Shell Epoxy Co., Ltd.), 2 parts of 
.gamma.-glycidoxypropyltrimethoxysilane (available from Shin-Etsu Silicon 
Co., Ltd.), and 300 parts of THF (solvent). The mixture was stirred at 
23.degree. C. for approximately 5 hours to give a liquid adhesive 
composition for electronic parts (viscosity at 30.degree. C.: 45 poise). 
The liquid adhesive composition maintained the homogeneous condition and 
an appropriate viscosity after storage at room temperature for one week. 
The liquid adhesive composition was coated on a polyester film having a 
release coating (Binasheet, available from Fujimori Industries Co., Ltd.), 
and dried at 120.degree. C. for 10 min. The dried adhesive composition 
coating was easily separated from the polyester film to give an adhesive 
tape of 35 .mu.m thick for electronic parts. The obtained adhesive tape 
showed the same Tg as that of the polyimide siloxane employed. The 
adhesive tape was heated to 250.degree. C. for 10 min., in a GC-MS (of 
Shimazu Seisakusho Co., Ltd.) and observed production of gaseous material. 
Almost no gas production was observed. 
The adhesive tape was placed between a pair of the aforementioned 42 alloy 
foil (thickness: 25 .mu.m) and pressed in a heat press at 300.degree. C. 
and 50 kg/cm.sup.2 for 30 min. The resulting composite was subjected to 
the 180.degree. peeling test. A satisfactory adhesion strength such as 2.8 
kg/cm was observed. No air bubbles were observed in the adhesive film. 
The composite was allowed to stand in a hot dryer under the conditions set 
forth in Table 3. The composite was then taken out of the dryer and 
subjected to measurement of adhesion strength. The retention of adhesion 
strength was then calculated and is set forth in Table 3. 
EXAMPLES 2-3 AND COMISON EXAMPLE 1-2 
In the same manner as in Example 1, polyimide siloxanes having the 
composition and characteristics set forth in Table 1 were prepared and 
mixed with other components set forth in Table 1 to give adhesive 
polyimide composition films. The films were subjected to the same tests as 
in Example 1. The test results are set forth in Table 2. 
The composites of Examples 2 and 3 were allowed to stand in a hot dryer 
under the conditions set forth in Table 3. Each composite was then taken 
out of the dryer and subjected to measurement of adhesion strength. The 
retention of adhesion strength was then calculated and is set forth in 
Table 3. 
In Comparison Example 2, a polymer precipitated in the course of 
polymerization reaction and no homogeneous adhesive composition was 
obtained. 
TABLE 1 
______________________________________ 
Polyimide siloxane (Ps) 
Composition 
Components 
Ex- (amount, Components 
Viscosity 
ample mM) (.eta..sub.inh) 
Mn Tg (parts) (poise) 
______________________________________ 
Ex. 1 a-BPDA 90 0.52 15,600 
234 Ps-1 100 
45 
BAPS 20 Ep807 5 
BAPP 70 GPTMSi 2 
THF 200 
Ex. 2 a-BPDA 70 0.58 16,200 
245 Ps-2 100 
65 
BAPS 10 Ep807 5 
BAPP 60 GPTMSi 2 
THF 200 
Ex. 3 a-BPDA 70 0.58 16,200 
245 Ps-2 100 
65 
BAPS 10 
BAPP 60 GPTMSi 2 
THF 200 
Comp. a-BPDA 90 0.52 15,600 
234 Ps-1 100 
45 
Ex. 1 BAPS 20 Ep807 5 
BAPP 70 
THF 200 
Comp. a-BPDA 50 Polymer precipitated 
Ex. 2 BAPS 20 in the polymerization 
BAPP 30 reaction 
______________________________________ 
Remarks: Ps1 and Ps2 are the polyimide siloxane prepared in Examples 1 an 
2, respectively. GPTMSi is glycidoxypropyltrimethoxysilane. 
TABLE 2 
______________________________________ 
Adhesive film 
Adhesion 
Tg thickness Strength 
Gas production 
Example (.degree.C.) 
(.mu.m) (kg/cm) 
(200.degree. C., 10 min.) 
______________________________________ 
Ex. 1 230 35 2.8 Not observed 
Ex. 2 240 35 3.2 Not observed 
Ex. 3 245 35 2.2 Not observed 
Com. Ex. 1 
230 35 0.2 Not observed 
______________________________________ 
Remarks: "Not observed" means "almost no gas production was observed". 
TABLE 3 
______________________________________ 
Retention of Adhesion Strength (%) 
180.degree. C. .times. 1,000 hrs. 
200.degree. C. .times. 1,000 hrs. 
______________________________________ 
Ex. 1 100 98 
Ex. 2 100 94 
Ex. 3 100 97 
______________________________________ 
COMISON EXAMPLE 3 
The procedure of Example 3 was repeated except for replacing the silane 
coupling agent with N-phenyl-.gamma.-aminopropyltrimethoxysilane of the 
same amount to prepare an adhesive polyimide composition. 
The polyimide composition was processed in the same manner as in Example 1 
to give an adhesive tape and the adhesive tape was employed for preparing 
a three layer composite of a pair of the alloy foils and the polyimide 
layer. The adhesion strength determined was poor such as 0.2 kg/cm. 
COMISON EXAMPLE 4 
The procedure of Example 3 was repeated except for replacing the silane 
coupling agent with vinyltriethoxysilane of the same amount to prepare an 
adhesive polyimide composition. 
The polyimide composition was processed in the same manner as in Example 1 
to give an adhesive tape and the adhesive tape was employed for preparing 
a three layer composite of a pair of the alloy foils and the polyimide 
layer. The adhesion strength determined was poor such as 0.1 kg/cm. 
EXAMPLE 4 
The adhesive polyimide composition tape of Example 1 was placed between a 
pair of an aromatic polyimide film (Upilex, thickness: 50 .mu.m, available 
from Ube Industries Ltd., prepared from 3,3',4,4'-biphenyltetracarboxylic 
acid dianhydride and p-phenylenediamine) to give a three layer composite. 
The adhesion strength determined was as high as 1.8 kg/cm. 
EVALUATION OF WATER ABSORPTION 
The adhesive polyimide composition tapes of Examples 1 to 3 were measured 
in accordance with ASTM D570 by immersing the tape in water at 23.degree. 
C., for 24 hours. The measured water absorptions are satisfactorily low as 
those set forth below. 
Adhesive tape of Example 1: 0.6% 
Adhesive tape of Example 2: 0.7% 
Adhesive tape of Example 3: 0.7%