JPH05331424A - Film adhesive - Google Patents

Abstract

PURPOSE:To provide the film adhesive containing a polyimide resin having a specific structure as a main component, excellent in low water absorption, heat resistance and adhesive force to silicon substrates and metals, capable of adhering at a low temperature in a short time, and suitable as a material for mounting semiconductors. CONSTITUTION:The film adhesive is produced by applying an adhesive to the surface of a film, the adhesive containing an imide resin as a main component. The imide resin is produced by reacting (A) 3,3',4,4'-(diphenyl sulfone) tetracarboxylic dianhydride of formula I, (B) an arbitrary other acid component (e.g. a dicarboxylic acid such as phthalic anhydride), (C) bis-4-(aminophenoxy)phenyl sulfone of formula II [preferably bis-4-(4- aminophenoxy)phenyl sulfone], (D) alpha,omega-bis(3-aminopropyl)polydimethylsiloxane of formula III, and (E) an arbitrary other amine component (e.g. p- phenylenediamine) in ratios of A/(A+B)>=0.7, (C+D)/(C+D+E)>=0.7 and 0.5>=D/(C+D+E)>=0.05 and subsequently subjecting the reaction product to an imide ring-closing reaction.

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 low water absorption and excellent heat resistance, and is particularly suitable for use as a semiconductor mounting material for a silicon substrate or a metal, and has excellent adhesive strength to a low temperature and a short time. It is about.

[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 rather a small external shape. Is being requested. In response to this tendency, some new mounting methods have been proposed to cope with high density and high density mounting of semiconductor chips. One is a COL that puts a chip on a lead frame without a die pad proposed for a memory device.
(Chip-on-lead) structure and its developed form are LOC (lead-on-chip) structure in which leads are mounted on a chip. 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 a semiconductor chip and a lead frame, a lead frame and a plate, and lead frames, and the bonding reliability greatly affects the reliability of the device. .. Not only the reliability of withstanding the process temperature at the time of assembling the element, but also the reliability of adhesion at the time of absorbing moisture, heat of heat and the like. 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 type, acrylic resin type, rubber-phenol resin type thermosetting resin is used as adhesive, but there are many ionic impurities, heat curing requires high temperature and long time, 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.

On the other hand, several heat-resistant thermocompression-bondable film adhesives are known, for example, Japanese Patent Laid-Open No.
282283 discloses a polyamide-imide-based or polyamide-based hot-melt adhesive, and JP-A-58-157190 discloses a hot-melt adhesive.
A method for manufacturing a flexible printed circuit board using a polyimide adhesive, JP-A-62-235382, JP-A-62-235383 and JP-A-2-15663, describes a thermosetting polyimide film adhesive. Has been done. However, polyamide-based and polyamide-imide-based resins have a drawback that the water absorption rate becomes large due to the hydrophilicity of the amide group, and there is a limit in using them as adhesives for electronic applications requiring reliability. .. In addition, thermosetting polyimide film adhesives have a thermocompression bonding condition of 275 ° C and 50 kgf / cm.
² , Electronic components that are sensitive to heat, pressure, water, etc., such as needing to be cured for 30 minutes or a semi-cured state at high temperature for a long time, and condensation water being generated during curing In addition, it cannot be said to be sufficient as a film adhesive for applications requiring mass productivity. For these reasons, there is a demand for the development of adhesives suitable for new mounting forms.

[0006]

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 in a short time at a low temperature, 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.

[0007]

The present invention is directed to 3,3 ', 4,4'-diphenylsulfone tetracarboxylic dianhydride and bis-4.
-(Aminophenoxy) phenyl sulfone and α, ω-
A film adhesive containing a polyimide resin as a main component, which is reacted with bis (3-aminopropyl) polydimethylsiloxane to cause imide ring closure.

Used to obtain the polyimide resin of the present invention
3,3 ′, 4,4′-diphenylsulfone tetracarboxylic dianhydride (hereinafter abbreviated as DSDA) has the formula (1), bis-4- (aminophenoxy) phenylsulfone has the formula (2), α, ω-bis (3-aminopropyl) polydimethylsiloxane (hereinafter A
(Abbreviated as PPS) is represented by formula (3). The amine represented by the formula (2) includes bis-4- (4-aminophenoxy) phenyl sulfone (hereinafter abbreviated as BAPS) and bis-4- (3-aminophenoxy) phenyl sulfone (hereinafter (Abbreviated as BAPSM), and BAPS is preferably used from the viewpoint of heat resistance.

[0009]

[Chemical 1]

[Chemical 2]

[Chemical 3]

In the present invention, in combination with the above DSDA,
3 ', 4,4'-biphenyltetracarboxylic dianhydride, 3,3',
4,4'-benzophenone tetracarboxylic dianhydride, 1,2,
Tetra such as 4,5-benzenetetracarboxylic dianhydride, 4,4'-oxydiphthalic acid dianhydride and 2,2'-bis (4- (3,4-dicarboxyphenyl) phenyl) propane dianhydride Carboxylic dianhydrides and further dicarboxylic acid anhydrides such as phthalic anhydride can be used as a molecular weight modifier.

Further, in combination with α, ω-bis (3-aminopropyl) polydimethylsiloxane, BAPS and BAPSM,
For example, 1,4-bis (3-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 2,2-bis (4- (4 -Aminophenoxy) phenyl) propane, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 2,2-bis-4-aminophenylhexafluoropropane, 2,2-bis-4-aminophenoxyphenylhexafluoropropane, 4,4'-diaminobenzanilide, m-phenylenediamine, p-phenylenediamine, 4, Diamines such as 4'-diaminodiphenylmethane and 2,4-diaminotoluene can be used.

In the present invention, it is important that the molar ratio of each of the acid component DSDA and the amine components APPS, BAPS, BAPSM is within the range of each of the following formulas. [DS
DA] = amol, [other acidic components] = bmol, [BAP
S] + [BAPSM] = c mol, [APPS] = d mol, [other amine component] = e mol a / (a + b) ≧ 0.7 (c + d) / (c + d + e) ≧ 0.7 0.5 ≧ d / (c + d + e ) ≧ 0.05 When the molar ratio is not within the above range, the heat resistance is remarkably inferior, the glass transition temperature is extremely low and the characteristics at high temperature are deteriorated, or the solubility in an organic solvent is lowered, which is not preferable. Particularly, when DSDA, which is an essential component, is less than 70 mol% of the acid component, the obtained polyimide resin is not dissolved in an organic solvent, and the glass transition temperature becomes low, so that the bonding workability is remarkably deteriorated, which is not preferable. Also AP
When PS exceeds 50 mol%, on the contrary, the glass transition temperature becomes low and the heat resistance becomes remarkably poor. Also, AP
When PS is less than 5 mol%, the phenomenon that the solubility in an organic solvent is poor after imidization, the adhesion to an adherend becomes poor, and the adhesion in a short time becomes difficult, and the water absorption rate becomes remarkable. Is 1% or more, which is not suitable for the purpose of the present invention.

The APPS used in the present invention preferably has a value of n in the formula (3) of 0 to 10, and n = 4 to 10
Or a mixture of n = 0 and n = 4 to 10 monomers is preferably used especially in applications where importance is attached to adhesiveness.

The molar ratio of the acid anhydride 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 the molecular weight and physical properties of polymers, especially the 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 as an adhesive, it is necessary to have a high molecular weight to some extent. In the present invention, the equivalent ratio r of the acid component and the amine component is more preferably 0.950 ≤ r ≤ 1.02, more preferably 0.975 ≤
It is preferably in the range of r ≤ 1.02. However, r = [equivalent number of all acid components] / [equivalent number of all amine components]. r is 0.
If it is less than 950, the molecular weight is low and it becomes brittle, so the adhesive strength becomes weak. On the other hand, when it exceeds 1.02, unreacted carboxylic acid is decarbonated during heating and causes 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 type may be used, or two or more types 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 nonpolar solvent in the mixed solvent is preferably 30% by weight or less. Non-polar solvent
This is because if the content is 30% by weight or more, the solubility of the reaction solvent may decrease and polyamic acid may precipitate.

The polyamic acid solution thus obtained is subsequently heated and dehydrated 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 incompatible 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, but for electronics use, the aromatic hydrocarbon is 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 rate is low, imidization occurs due to heat at the time of bonding 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 may be used as it is, but it is preferable to introduce the polyimide solution into a poor solvent to reprecipitate and precipitate the polyimide resin to remove unreacted monomers for purification. The purified, 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 it is preferable to select a solvent having a low boiling point, preferably a boiling point of 200 ° C. or less, in consideration of workability in the coating and drying step. In the present invention, examples of the solvent having a temperature of 200 ° 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. The amide solvents N, N-dimethylformamide and N, N-dimethylacetamide have a boiling point of 200 ° C or less, but they have a strong interaction with polyimide and require a high temperature of 200 ° C or more for drying, and also have a hygroscopic property. Since it is high, the film is whitened when the varnish is applied, and therefore its use is not preferable.

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

In the present invention, a polyimide resin film adhesive is usually obtained by casting or coating a polyimide resin solution (varnish). For example, a release sheet such as a roll, a metal sheet or a polyester sheet. A film is formed on top of it with a flow coater, roll coater, etc., and after heating and drying it is peeled off to form a film adhesive, or a heat-resistant film substrate is used as a support, and a film layer is similarly formed on one or both sides. And a film adhesive together with the support.

The heat-resistant film base material used in the present invention is that the polyimide resin film has a small coefficient of thermal expansion and is excellent in dimensional stability against temperature changes, is flexible and easy to handle, and the adhesive resin of the present invention. It is preferable in that it has excellent adhesion with. Especially glass transition temperature of 350 ℃
The above polyimide resin is excellent in performance as a film adhesive and workability and stability in the step of applying and drying a polyimide resin varnish as an adhesive layer.

For coating and drying the adhesive varnish on the substrate film, an apparatus combining a hot air drying furnace with a flow coater or roll coater can be used. After applying the polyimide resin varnish, the polyimide resin varnish is introduced into a hot air drying oven and dried at a temperature and an air volume sufficient to vaporize the solvent of the polyimide resin varnish.

The method of using the film adhesive of the present invention is not particularly limited, but the film adhesive can be used as an adhesive tape by thermocompression bonding with a heat block that is cut into a predetermined shape and heated. ..

[0024]

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. Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

[0026]

【Example】

(Example 1) NMP900 dehydrated and refined in a four-necked flask equipped with a dry nitrogen gas introduction tube, a cooler, a thermometer, and a stirrer.
g and 210 g of xylene, and stir vigorously for 10 minutes while flowing nitrogen gas. Next, BAPS 60.5503g (0.140
Mol) and α, ω-bis (3-aminopropyl) polydimethylsiloxane (APPS) 43.5000 g (average molecular weight 870, 0.05
0 mol) and 2.4852 g (0.010 mol) of bis (3-aminopropyl) tetramethyldisiloxane (APPS, n = 0) are added and the system is stirred until it becomes uniform. After uniform dissolution,
The system was cooled to 5 ° C in an ice water bath, and DSDA 61.9203 g (0.19
9 mol) in powder form over 15 minutes, then 3
Stirring was continued for hours. During this time, the flask was kept at 5 ° C.

After that, the nitrogen gas introducing pipe and the cooler were removed,
The flask was fitted with a Dean-Stark tube filled with xylene. Instead of the oil bath, the system was heated to 200 ° C. and the generated water was removed from the system. After heating for 5 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.
The solid content was filtered and then dried under reduced pressure at 80 ° C. for 12 hours to remove the solvent. When the infrared absorption spectrum was measured by the KBr tablet method, an absorption of 5.6 μm derived from a cyclic imide bond was observed, but an absorption of 6.06 μm derived from an amide bond was not observed, and this resin was 100% imide. It was confirmed that it has changed. Polyimide resin 151.8 thus obtained
Cyclohexanone / diglyme (50% yield 90.1%)
/ 50 W / W%) to prepare a polyimide resin varnish having a solid content of 20%.

This polyimide resin varnish was applied on a mirror-polished stainless steel plate and dried at 120 ° C. for 0.5 at 120 ° C. in a hot air circulation dryer.
After drying for an hour, it was peeled from the stainless plate. Four rounds of this film were fixed to an iron frame and heated and dried at 220 ° C. for 1 hour.
After cooling, the thickness of the film was measured and found to be 26 μm. The obtained film showed no tackiness at room temperature and was tack-free.

This film was hot pressed with a heat block on a 42 alloy plate to prepare a test piece. Bonding conditions
After thermocompression bonding at 310 ° C. for 2 seconds, the pressure was released, and annealing was performed at 310 ° C. for 30 seconds. The pressure applied to the bonding surface was 4 kgf / cm ^{2 as} a result of calculation from the gauge pressure and the bonding area. The 180-degree peel strength of this test piece was 1.97 kgf / cm, which showed excellent adhesive strength. At the fractured surface, the adhesive resin layer was cohesively destroyed and no foaming was observed. The results including other performances are shown in Table 1.

Example 2 The polyimide resin obtained in Example 1 was coated on both sides with a reverse roll coater on a polyimide film (Upilex SGA, Ube Industries, Ltd.),
A double-sided adhesive tape was obtained. The maximum drying temperature was 210 ° C and the drying time was 10 minutes. This adhesive tape was heat-bonded to the 42 alloy plate under the same conditions as in Example 1. As a result of the 180-degree peel test, there was no trouble such as foaming and the strength was 1.84 kgf / cm.

Example 3 As in Example 1, BAPS
M 56.2253 g (0.130 mol) and APPS 60.9000 g (average molecular weight 870, 0.070 mol) and DSDA 71.5124 g (0.20 mol)
(0 mol) and polyamic acid were prepared and further heated to imidize. This was reprecipitated with methanol in the same manner as in Example 1 and then applied to a polyimide film to prepare a film adhesive. Table 1 shows the evaluation results of the polyimide resin and the film adhesive.

(Examples 4 to 6) In the same manner as in Example 1, polyimide resin varnishes were prepared with the types and proportions of the acid and amine components shown in Table 1 to prepare film adhesives. These performances are shown in Table 1.

In Table 1, the numerical values of the blends are the blending equivalent ratios of the respective components, and the water absorption rate is the saturated water absorption rate after treatment for 500 hours (HH-500) in an environment of 85 ° C. and 85% RH. The generated gas and the generated water are values determined by the GC-MS method and the Karl Fischer method for the gas generated when heated at 250 ° C. for 15 minutes. S in the solubility column indicates that the substance is soluble in the corresponding solvent, and I indicates that it is not.

[0034]

[Table 1]

(Embodiment 7) In the same manner as in Embodiment 1, AP
PS / BAPSM and DSDA are a / (a + b) = 1.00
0, (c + d) / (c + d + e) = 1.000, d / (c +
It reacted at d + e) = 0.700. After thermal imidization in solution,
Reprecipitation and purification were performed to obtain a polyimide resin. This polyimide resin was well dissolved in a mixed solvent of cyclohexanone / diglyme. It was necessary to pay attention to the fact that when the film was put on an iron frame and dried at 150 ° C, it drooped down. The glass transition temperature was measured to be 103 ° C.

(Comparative Example 1) In the same manner as in Example 1, 26.0311 g (0.130 mol) of 4,4'-diaminodiphenyl ether, 60.9000 g of APPS (average molecular weight of 870, 0.070 mol) and 1,4
2,4,5-Benzenetetracarboxylic dianhydride 43.5372g
A polyamic acid was prepared from (0.200 mol). It was further imidized by heating, but as the reaction proceeded, the resin precipitated,
No soluble polyimide resin was obtained.

Comparative Example 2 As in Example 1, BAPS
M 56.2253g (0.130mol) and APPS 60.9000g (0.0
Polyamic acid was prepared from 70 mol) and 64.3171 g (0.200 mol) of 3,3 ', 4,4'-benzophenone tetracarboxylic acid dianhydride, and further imidized by heating. After reprecipitation purification, it tried to dissolve in cyclohexanone / diglyme mixed solvent, but it did not dissolve, so it was dissolved in NMP. This was applied to a polyimide film in the same manner as in Example 2. When the drying conditions are 120 ° C. for 1 hour and 220 ° C. for 1 hour, bubbles are generated due to the residual solvent at the time of adhesion. In the evaluation of the adhesion of the 42 alloy to the plate,
When pressure was applied at 310 ° C. for 2 seconds, the peel strength was 0.01 kgf / cm or less, which was quite weak.

Comparative Example 3 In the same manner as in Example 1, BA
PS and DSDA were reacted to obtain a polyimide resin. At this time, a / (a + b) = 1.000, (c + d) / (c + d +
e) = 1.000 and d / (c + d + e) = 0. This polyimide resin did not dissolve in a low boiling point solvent such as cyclohexanone. Since it dissolves in NMP, it was dissolved in NMP to obtain a film. 180 degree peel strength is 0.5kgf / cm
The film thus obtained had an adhesion temperature of 380 ° C. or higher, and a high water absorption rate of 3.08% after HH-500 treatment.

[0039]

According to the present invention, it is possible to provide a highly reliable film adhesive which has both low water absorption, heat resistance and bonding workability. In particular, the impurity level is low,
Since the gas component generated during heating is extremely low, the lead frame is not contaminated. Further, it can be adhered in a short time and is industrially extremely useful as a semiconductor packaging material.

Claims (4)

[Claims] 1. 3,3 ′, 4,4′-Diphenylsulfone tetracarboxylic dianhydride, bis-4- (aminophenoxy) phenyl sulfone and α, ω-bis (3-aminopropyl) polydimethylsiloxane A film adhesive whose main component is a polyimide resin obtained by reacting an imide to cause imide ring closure. 2. 4,4'-Diphenylsulfone tetracarboxylic acid dianhydride a mole, other acid component b mole, bis-4- (aminophenoxy) phenyl sulfone c mole, α, ω-bis (3-amino Propyl) polydimethylsiloxane d mol,
The other amine component (e mole) is a / (a + b) ≧ 0.7, (c
+ D) / (c + d + e) ≧ 0.7 and 0.5 ≧ d / (c +
The film adhesive according to claim 1, wherein a ratio of d + e) ≧ 0.05. 3. The film adhesive according to claim 1, wherein the bis-4- (aminophenoxy) phenyl sulfone is bis-4- (4-aminophenoxy) phenyl sulfone. 4. A film adhesive obtained by applying the adhesive according to claim 1, 2 or 3 to one side or both sides of a heat resistant film substrate.