JPH06172737A - Film adhesive and its production - Google Patents

Abstract

PURPOSE:To obtain a highly reliable film adhesive which has a low water absorptivity, a high heat resistance, and a good workability in adhesion. CONSTITUTION:This film adhesive is obtd. by using, as the main component, an org.solvent-sol. polyimide resin which is obtd. by reacting an acid component comprising a¦¦x¦¦ mol of 4,4'-oxydiphthalic dianhydride and b¦¦x¦¦ mol of pyromellitic anhydride with an amine component comprising c¦¦x¦¦ mol of 2,2- bis[4-(4-aminophenoxy)phenyl]propane, d¦¦x¦¦ mol of 1,3-bis(3-aminophenoxy) benzene and/or dimethylphenylenediamine, and e¦¦x¦k mol of alpha,omega-bis(3- aminopropyl)polydimethylsiloxane in such molar amts. of (a), (b), (c), (d), and (e) as to satisfy the relations: a/(a+b)>=0.8, b/(a+b)<=0.2, and 0.05<=e/(c+d+e)<=0.5 and subjecting the reactional product to imidation by cyclization. The adhesive, contg. little impurities and releasing very little gaseous matters on heating, is very useful industrially as a material for microelectronics and semiconductor mounting.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film adhesive which has a low water absorption property and an excellent heat resistance and is particularly suitable for use as a semiconductor mounting material in a silicon substrate or a metal, and has excellent adhesive strength to a low temperature and a short time. And its manufacturing method.

[0002]

2. Description of the Related Art In recent years, while semiconductor chips have become larger due to higher functionality and larger capacity, the size of the package has not changed from the conventional one due to restrictions on printed circuit design, demand for miniaturization of electronic equipment, or a rather small external shape. Is being requested. In response to this tendency, some new mounting methods have been proposed for high density and high density mounting of semiconductor chips. One is a COL that mounts a chip on a lead frame without a die pad proposed for memory devices.
It is a LOC (lead-on-chip) structure in which leads are mounted on a chip that is a (chip-on-lead) structure and its development. On the other hand, the logic element has a multi-layered lead frame structure in which a power source and a ground are provided in different frames and a metal plate for heat dissipation is multi-layered. According to these, it is possible to rationalize the wiring in the chip and wire bonding, to speed up the signal by shortening the wiring, to dissipate heat generated due to the increase in power consumption, and to reduce the element size.

In this new mounting mode, there are bonding interfaces of the same kind and different materials such as the semiconductor chip and the lead frame, the lead frame and the plate, and the lead frames, and the bonding reliability thereof has a great influence on the reliability of the element. . Not only the reliability of withstanding the process temperature at the time of assembling the element, but also the bonding reliability at the time of moisture absorption, heat and humidity. Further, the workability of bonding is also an important item.

Conventionally, a paste-like adhesive or a heat-resistant base material coated with an adhesive has been used for these adhesions. Epoxy resin-based, acrylic resin-based, and rubber-phenol resin-based thermosetting resins are used as adhesives, but there are many ionic impurities, heat curing requires high temperature and long time, and productivity is poor, heat curing It is hard to say that the requirements for a highly reliable adhesive such as a large amount of volatile components that contaminate leads and high hygroscopicity are satisfied, and no satisfactory material is found. There is a demand for the development of adhesives suitable for new mounting forms.

[0005]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention In the present invention, as a result of intensive studies to obtain a film adhesive having low water absorption and excellent heat resistance, which can be bonded at a low temperature in a short time, a polyimide resin having a specific structure has the above problems. The present invention has been found to solve the above problems and has reached the present invention.

[0006]

The present invention provides a film adhesive containing a polyimide resin having a specific structure as a main component of the adhesive.
And its manufacturing method.

The present invention uses 2,2-bis (4- (4-aminophenoxy) phenyl) propane as an acid component of a mol of 4,4'-oxydiphthalic acid dianhydride and b mol of pyromellitic dianhydride. c mol, one or two kinds of diamine selected from the group of 1,3-bis (3-aminophenoxy) benzene and dimethylphenylenediamine, and α, ω-bis (3-aminopropyl) polydimethyl The siloxane e mole is used as an amine component, and the molar ratio of a, b, c, d, e is a / (a +
b) ≧ 0.8, b / (a + b) ≦ 0.2, and 0.05 ≦ e /
(C + d + e) ≦ 0.5, which is a polyimide resin soluble in an organic solvent in which both components are reacted to cause imide ring closure, and the molecular end of the polyimide resin is an acid anhydride f represented by the general formula (1). Mol, or end-capped with g mol of the aromatic amine represented by the general formula (2), a, b, c,
The molar ratio of d, e, f, g is a / (a + b + 0.5f) ≧
0.8, b / (a + b + 0.5f) ≦ 0.2, 0.01 ≦ f / (a
+ B + 0.5f) ≤ 0.05, 0.01 ≤ g / (c + d + e + 0.
5g) ≤ 0.05, 0.05 ≤ e / (c + d + e + 0.5g) ≤
It is a film adhesive mainly composed of a polyimide resin soluble in an organic solvent which is imide ring-closed by reacting both components at a ratio of 0.5 and either f or g is 0.

[Chemical 1] (Where X is

[Chemical 2] At least one group selected from

[Chemical 3] (In the formula, Y is a hydrogen atom or at least one group selected from methyl, ethyl, propyl, butyl, phenyl, methoxy, ethoxy, propoxy, butoxy, and phenoxy groups.)

The α, ω-bis (3-aminopropyl) polydimethylsiloxane used to obtain the polyimide resin of the present invention is represented by the formula (3).

[Chemical 4]

The amount ratio of 4,4'-oxydiphthalic dianhydride, which is the main constituent of the acid component, is extremely important for the solubility of the obtained polyimide resin. The feature of the invention of dissolution is lost.

The α, ω-bis (3-aminopropyl) polydimethylsiloxane represented by the formula (3) preferably has n = 0 to 10 and, particularly, when the value of n is 4 to 10, the glass transition temperature is It is preferable in terms of adhesiveness and heat resistance. In addition, blending n = 0 and the above n = 4 to 10 is preferable especially for applications where importance is placed on adhesiveness.

Other acid anhydrides and diamines used in the production of polyimides, for example, 4,4'-oxydiphthalic acid dianhydride, pyromellitic dianhydride, 3,3 ', 4,4'-diphenylsulfone tetracarboxylic acid Dianhydride, 2,2-bis (4- (4-aminophenoxy) phenyl) hexafluoropropane (B
APPF), 2,2-bis (4-aminophenoxy) hexafluoropropane (BAPF), bis-4- (4-aminophenoxy) phenyl sulfone (BAPS), bis-4- (3-aminophenoxy) phenyl sulfone ( It is possible to add BAPSM) in a small amount within a range that does not impair the characteristics.

It is important that the amount ratio of each component is within the above range. If the content of α, ω-bis (3-aminopropyl) polydimethylsiloxane is less than 5 mol% of the total amine components, low hygroscopicity is characteristic. If it does not appear and exceeds 50 mol%, the glass transition temperature is remarkably lowered and a problem occurs in heat resistance. Regarding the molar ratio of 2,2-bis (4- (4-aminophenoxy) phenyl) propane, it is preferably 10 to 90 mol% of the total amine components. There is a problem with sex.

By adding dimethylphenylenediamine, the heat resistance can be improved without lowering the solubility in a low boiling point solvent. As dimethylphenylenediamine, 2,5-dimethyl-p-phenylenediamine, 2,4-
Dimethyl-m-phenylenediamine is preferred. When low-temperature adhesion is required for adhesives, 1,3-bis (3-
Aminophenoxy) benzene can be added.

When the polyimide resin is used as an adhesive, the end of the molecule is end-capped and the molecular weight is controlled to obtain a melt viscosity suitable for adhesion to an adherend, improving wettability, The adhesive strength can be increased. The amount ratio of the acid anhydride or the aromatic amine as the end cap agent is preferably in the range of 1 mol% to 5 mol%. If it is less than 1 mol%, the molecular weight becomes too high and the solubility in a low boiling point solvent, which is a feature of the present invention, decreases, and in applications where importance is placed on adhesiveness, wettability deteriorates due to an increase in melt viscosity, which is not preferable. When it exceeds 5 mol%, the molecular weight is remarkably reduced, and heat resistance becomes a problem. Is preferable, and if it exceeds the above range, problems occur in solubility and heat resistance.

The end cap agent is represented by the general formula (1)
And an aromatic amine represented by the general formula (2). As the acid anhydride, phthalic anhydride, maleic anhydride, nadic acid anhydride, etc., and as the aromatic amine, p-methylaniline, p-methoxyaniline,
p-phenoxyaniline or the like is used.

The equivalent ratio of the acid component and the amine component in the polycondensation reaction is an important factor that determines the molecular weight of the polyamic acid obtained. It is well known that there is a correlation between polymer molecular weight and physical properties, especially number average molecular weight and mechanical properties. The larger the number average molecular weight, the better the mechanical properties. Therefore, in order to obtain practically excellent strength, it is necessary that the polymer has a high molecular weight to some extent. In the present invention,
The equivalent ratio r of the acid component and the amine component is 0.900 ≤ r ≤ 1.06, more preferably 0.975 ≤
It is preferable that r is within the range of 1.06. However, r = [equivalent number of all acid components] / [equivalent number of all amine components]. r is 0.
If it is less than 900, the molecular weight is low and it becomes brittle, so the adhesive strength becomes weak. On the other hand, if it exceeds 1.06, unreacted carboxylic acid may be decarboxylated during heating to cause gas generation and foaming, which is not preferable.

The reaction between the tetracarboxylic dianhydride and the diamine is carried out by a known method in an aprotic polar solvent. The aprotic polar solvent is N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMA
C), N-methyl-2-pyrrolidone (NMP), tetrahydrofuran (THF), diglyme, cyclohexanone,
1,4-dioxane and the like. The aprotic polar solvent is
Only one kind may be used, or two or more kinds may be mixed and used. At this time, a non-polar solvent compatible with the aprotic polar solvent may be mixed and used. Aromatic hydrocarbons such as toluene, xylene and solvent naphtha are often used. The proportion of the non-polar solvent in the mixed solvent is preferably 30% by weight or less. This is because if the amount of the nonpolar solvent is 30% by weight or more, the solubility of the solvent may decrease and polyamic acid may precipitate. The reaction between the tetracarboxylic dianhydride and the diamine is carried out by dissolving the well-dried diamine component in the dehydrated and purified reaction solvent described above, and the ring closure rate is 98%, more preferably 99% or more of the well-dried tetracarboxylic dianhydride. Anhydrous is added to drive the reaction.

The polyamic acid solution thus obtained is subsequently heated to dehydration and cyclization in an organic solvent to form an imidized polyimide. Since the water generated by the imidization reaction interferes with the ring-closing reaction, an organic solvent that is not compatible with water is added to the system to azeotropically evaporate it and use a device such as a Dean-Stark tube to remove it from the system. To discharge. Dichlorobenzene is known as an organic solvent that is incompatible with water,
For electronics use, the above-mentioned aromatic hydrocarbons are preferably used because chlorine components may be mixed therein.
Further, the use of compounds such as acetic anhydride, β-picoline and pyridine as a catalyst for the imidization reaction is not hindered.

In the present invention, the higher the degree of imide ring closure, the better, and if the imidization ratio is low, imidization occurs due to heat during use and water is not generated, which is not preferable. Therefore, 95% or more, more preferably 98% or more. It is desirable that the imidization ratio of is achieved.

In the present invention, the obtained polyimide solution can be used as it is as a coating varnish. Also,
It is also possible to use the polyimide solution as a solid polyimide resin by pouring the polyimide solution into a poor solvent to reprecipitate and precipitate the polyimide resin to remove unreacted monomers, and to purify and dry the polyimide resin. In applications where high-temperature processes are disliked or where impurities and foreign substances are particularly problematic, it is preferable to dissolve them again in an organic solvent to obtain a filtration / purification varnish. The solvent used at this time can be selected from those having a low boiling point in consideration of workability.

In the polyimide resin of the present invention, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone and cyclohexanone are used as ketone solvents, and 1,4-dioxane, tetrahydrofuran and diglyme are used as ether solvents having a boiling point of 180 ° C. or less. It can be used as a low boiling point solvent. These solvents may be used alone or in combination of two or more. If the imidization ratio is low, imidization occurs due to heat during adhesion and water is generated, which is not preferable. Therefore, it is necessary that the conditions are such that an imidization ratio of 95% or more, and more preferably 98% or more can be achieved.

In the present invention, the obtained polyimide solution may be directly applied to the support, but the polyimide solution is put into a poor solvent to reprecipitate and precipitate the polyimide resin to remove unreacted monomers for purification. It is preferable. Refining,
The filtered and dried polyimide resin is dissolved again in an organic solvent to form a varnish. The solvent used at this time may be the same as the reaction solvent, but has a low boiling point in consideration of workability in the coating and drying step,
It is preferable to select a solvent having a boiling point of 180 ° C. or lower. In the present invention, examples of the solvent having a temperature of 180 ° C. or lower include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone and cyclohexanone as the ketone solvent, and 1,4-dioxane, tetrahydrofuran and diglyme as the ether solvent. These solvents may be used alone or in combination of two or more. Amide-based solvents N, N-dimethylformamide, N, N-dimethylacetamide dissolves the polyimide resin of the present invention well at a boiling point of 180 ° C or lower, but the interaction with the polyimide is strong and a high temperature of 250 ° C or higher is required for drying. Its use is not preferable because it is necessary and because the film has high hygroscopicity, the film is whitened when the varnish is applied.

If necessary, various additives such as a leveling agent, a leveling agent, and a defoaming agent can be added to the polyimide resin varnish for providing surface smoothness. Further, an aromatic hydrocarbon solvent can be used within a range in which the solvent is uniformly dissolved in order to control the evaporation rate of the solvent.

To form a film adhesive, a polyimide resin varnish is cast to form a film, which is used alone or as a film support. For the casting of the polyimide resin varnish, an apparatus combining a coating facility such as a roll coater and a hot air drying oven can be used. After applying the polyimide resin varnish to the support,
It is introduced into a hot air drying oven and dried at a temperature and air volume sufficient to vaporize the solvent of the varnish. When it is used as a film alone, it is peeled from the support, and when it is used integrally, it is used while it is attached to one side or both sides of the support.
The method of using the film adhesive of the present invention is not particularly limited, but it can be used as an adhesive tape, for example, by thermocompression bonding with a heat block that is cut into a predetermined shape and heated and bonded.

[0025]

The film adhesive of the present invention is characterized in that the main component is a completely imidized polyimide resin having a specific structure which is soluble in an organic solvent having a low boiling point. By reprecipitating and refining the adhesive polyimide resin, it is possible to achieve extremely low levels of ionic impurities, and it is also possible to eliminate gas generated during heating almost completely by using imidization using a solvent with a low boiling point. You can

Further, it has low water absorption and excellent heat resistance, and can be bonded in an extremely short time as compared with a thermosetting adhesive which involves a chemical reaction. By processing into a tape shape, the workability of bonding and the dimensional accuracy of the bonded portion can be made excellent. The present invention is described in detail below with reference to examples, but the present invention is not limited to these examples.

[0027]

【Example】

(Example 1) NMP762 dehydrated and refined in a four-necked flask equipped with a dry nitrogen gas introduction tube, a condenser, a thermometer, and a stirrer.
Add g and stir vigorously for 10 minutes while flowing nitrogen gas. Next, 2,2-bis (4- (4-aminophenoxy) phenyl) propane (BAPP) 49.2618 g (0.120 mol), 2,5-dimethyl-p-phenylenediamine (DPX) 16.3435 g (0.12 mol)
0 mol) and α, ω-bis (3-aminopropyl) polydimethylsiloxane (APPS) 133.9200 g (average molecular weight 837.0
(0, 0.160 mol), and the system is heated to 60 ° C and stirred until uniform. After uniform dissolution, phthalic anhydride 2.926
4 g (0.020 mol) was added and stirred for 1 hour. Then, the system was cooled to 5 ° C in an ice water bath, and 99.2710 g (0.320 mol) of 4,4'-oxydiphthalic acid dianhydride and pyromellitic dianhydride 1
5.2686 g (0.070 mol) was added in powder form over 15 minutes and stirring was continued for 3 hours. During this time, the flask was kept at 5 ° C.

After that, the nitrogen gas introducing pipe and the cooler were removed,
A Dean-Stark tube filled with xylene was attached to the flask, and 191 g of toluene was added to the system. Instead of the oil bath, the system was heated to 175 ° C. and the water generated was removed from the system. After heating for 4 hours, generation of water from the system was not observed. After cooling, this reaction solution was poured into a large amount of methanol to precipitate a polyimide resin. After filtering the solids, 80
287.22 g (yield 90.6
%) Solid resin was obtained. When the infrared absorption spectrum was measured by the KBr tablet method, it was found to be 5.6
Absorption of μm was observed, but 6.06 μm derived from amide bond
It was confirmed that the resin was almost 100% imidized. At this time, the molar ratio of acid and amine is a / (a + b + 0.5f) = 0.8,
b / (a + b + 0.5f) = 0.175, e / (c + d + e)
= 0.4.

The polyimide resin thus obtained was dissolved in cyclohexanone / toluene (90/10 w / w%),
A polyimide resin varnish having a solid content of 25% was prepared. This varnish was coated with a reverse roll coater on a polyimide film (trade name Upilex SGA, thickness 50 μm, Ube Industries).
(Manufactured by K.K.) to obtain an adhesive tape having an adhesive layer with a thickness of 30 μm. The maximum drying temperature was 185 ° C and the drying time was 6 minutes. This adhesive tape was hot pressed onto a 35 μm copper foil to prepare a test piece. The treated surface of the copper foil was thermocompression bonded at 250 ° C. for 2 seconds, the pressure was released, and the copper foil was annealed at 250 ° C. for 30 seconds. The pressure applied to the adhesive surface is calculated from the gauge pressure and the adhesive area, and the result is 4 kgf.
It was / cm ² . The 180 degree peel strength of this test piece is 2.68 kg.
f / cm, showing excellent adhesive strength. At the fracture surface, the adhesive resin layer was cohesively destroyed and no foaming was observed.

Example 2 The varnish of Example 1 was mixed with a biaxially stretched polyester film (trade name: diamond foil, thickness: 50 μm).
m, manufactured by Mitsubishi Rayon Co., Ltd.) and the maximum drying temperature is 18
The drying time was 6 minutes at 5 ° C. After drying, the film was peeled from the polyester film to obtain a single-layer film without a support and having a thickness of 32 μm. Peeling was easy and there was no particular problem. Example 1
Table 1 shows the results of adhesion to the shiny side of the copper foil in the same manner as in.

(Examples 3 to 5) Reaction was carried out in the same manner as in Example 1 to obtain a soluble polyimide resin. The evaluation results obtained for these polyimide resins are shown in Table 1. It can be seen that all have excellent performance as an adhesive tape.

[0032]

[Table 1]

In Table 1, ODPA is 4,4'-oxydiphthalic dianhydride, PMDA is pyromellitic dianhydride, PA is phthalic anhydride, and BAPP is 2,2-bis (4- (4 (4 -
Aminophenoxy) phenyl) propane, APB is 1,3-
Bis (3-aminophenoxy) benzene, DPX is 2,5-dimethyl-p-phenylenediamine, APPS is α, ω-bis (3-aminopropyl) polydimethylsiloxane, PP
A is an abbreviation for p-phenoxyaniline.

In addition, the numerical value of the compound is the compound equivalent ratio in each component, and the water absorption rate is 168 in an environment of 85 ° C. and 85% RH.
Saturated water absorption after leaving for a while (HH-168 treatment)
The generated water is a value obtained by quantifying the gas generated by heating at 250 ° C. for 15 minutes by the GC-MS method, and the water content by the Karl Fischer method. S in the solubility column indicates that the compound is soluble in the corresponding solvent.

(Comparative Example 1) A / (a + b) = 0.8, b / (a +) according to the formulation of Table 2 under the same conditions as in Example 1.
b) = 0.2 and e / (c + d + e) = 0.4 were reacted to obtain a polyimide resin. The polyimide resin thus obtained was mixed with cyclohexanone / toluene (90/10 w /
w%) to prepare a polyimide resin varnish having a solid content of 25% to prepare an adhesive tape. The 180 ° peel strength of the test piece of this adhesive tape and copper foil was 0.89 kgf / cm.

Comparative Example 2 The varnish of Comparative Example 1 was used in Example 2
When a 180 ° peel strength with a copper foil was measured by coating on a polyester film to form a film without a support, the result was 0.91 kgf / cm.

(Comparative Examples 3 to 4) Table 2 shows the results of evaluation of the polyimide resin obtained by reacting in the same manner as in Example 1.

[0038]

[Table 2]

The above examples show that the present invention can provide a polyimide resin which is soluble in an organic solvent and is excellent in heat resistance and low hygroscopicity.

[0040]

According to the present invention, it is possible to provide a highly reliable film adhesive having both low water absorption, heat resistance and workability for adhesion. In particular, the impurity level is low,
Since the gas component generated at the time of heating is extremely low, it is industrially extremely useful as a microelectronic material and a semiconductor mounting material.

[Procedure amendment]

[Submission date] November 12, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

The α, ω-bis (3-aminopropyl) polydimethylsiloxane represented by the formula (3) preferably has n = 1 to 10, and particularly, when the value of n is 4 to 10, the glass transition temperature is It is preferable in terms of adhesiveness and heat resistance. Further, it is preferable to blend n = 1 and the above n = 4 to 10 for use especially in applications where importance is attached to adhesiveness.

Claims (4)

[Claims] 1. A mole of 4,4′-oxydiphthalic acid dianhydride and b mole of pyromellitic dianhydride as acid components, and c mole of 2,2-bis (4- (4-aminophenoxy) phenyl) propane. And d mol of one or two diamines selected from the group of 1,3-bis (3-aminophenoxy) benzene and dimethylphenylenediamine, and α, ω-bis (3-aminopropyl)
With polydimethylsiloxane emol as an amine component,
The molar ratio of a, b, c, d, e is a / (a + b) ≧ 0.
8, b / (a + b) ≦ 0.2, and 0.05 ≦ e / (c + d
+ E) A film adhesive mainly composed of a polyimide resin which is soluble in an organic solvent and is imide ring-closed by reacting both components at a ratio of 0.5. 2. An acid component of 4,4′-oxydiphthalic acid dianhydride a mole and pyromellitic dianhydride b mole, and 2,2-bis (4- (4-aminophenoxy) phenyl) propane c mole And d mol of one or two diamines selected from the group of 1,3-bis (3-aminophenoxy) benzene and dimethylphenylenediamine, and α, ω-bis (3-aminopropyl)
Polydimethylsiloxane e mole as an amine component, and the end of the molecule of the polyimide resin is end-capped with f mole of the acid anhydride represented by the general formula (1) or g mole of the aromatic amine represented by the general formula (2). , A, b, c, d, e,
The molar ratio of f and g is a / (a + b + 0.5f) ≧ 0.8, b /
(A + b + 0.5f) ≤ 0.2, 0.01 ≤ f / (a + b + 0.5
f) ≦ 0.05, 0.01 ≦ g / (c + d + e + 0.5g) ≦
0.05, 0.05 ≤ e / (c + d + e + 0.5g) ≤ 0.5, and one of the main components is a polyimide resin soluble in an organic solvent that is imide ring-closed by reacting both components at a ratio where either f or g is 0. And film adhesive. [Chemical 1] (In the formula, X is At least one group selected from among (In the formula, Y is a hydrogen atom or at least one group selected from methyl, ethyl, propyl, butyl, phenyl, methoxy, ethoxy, propoxy, butoxy, and phenoxy groups.) 3. The method according to claim 1 or 2, wherein an organic solvent solution of a polyimide resin in which a polyamic acid is heated and dehydrated in an organic solvent to complete the imide ring-closure reaction is cast on one side or both sides of a support. Method for producing film adhesive. 4. The film adhesive according to claim 1, which is obtained by casting on a support using an organic solvent having a boiling point of 180 ° C. or lower, drying and peeling from the support. Production method.