JP3093062B2 - Film adhesive and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film adhesive capable of bonding in a short time at a low temperature with excellent adhesiveness to a silicon substrate or a metal which is suitable for a semiconductor mounting material, particularly an electronic application excellent in low water absorption and heat resistance. And its manufacturing method.

[0002]

2. Description of the Related Art In recent years, while semiconductor chips have been increased in size due to higher functions and larger capacities, the size of packages has not changed from the prior art due to restrictions on the design of printed circuits and demands for miniaturization of electronic equipment, or has a rather small outer shape. Is required. In response to this trend, several new mounting methods have been proposed for high-density semiconductor chips and high-density mounting. One is a COL that mounts a chip on a lead frame without a die pad proposed for memory devices.
There is a (chip-on-lead) structure and an LOC (lead-on-chip) structure in which leads are mounted on a chip, which is a development of the structure. On the other hand, a logic element has a multilayer lead frame structure in which a power supply and a ground are provided in separate frames, and a metal plate for heat dissipation is multilayered. According to these, it is possible to rationalize the wiring in the chip and wire bonding, to increase the signal speed by shortening the wiring, to dissipate the heat generated due to the increase in power consumption, and to reduce the element size.

In this new mounting mode, there are bonded 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 has a great influence on the reliability of the element. . This is not only the reliability that can withstand the process temperature during the element assembling work, but also the bonding reliability when absorbing moisture, when heating and the like. Further, the bonding workability is also an important item.

Heretofore, a paste-like adhesive or a heat-resistant base material coated with an adhesive has been used for such bonding. Epoxy resin, acrylic resin, and rubber-phenol resin thermosetting resins are used as adhesives, but they contain many ionic impurities, require high temperature and long time for heat curing, and have poor productivity. At times, a large amount of volatile components are generated to contaminate the lead, and high hygroscopicity is not satisfied with the demand for a highly reliable adhesive, and no satisfactory material is found. There is a need to develop an adhesive suitable for a new mounting form.

[0005]

SUMMARY OF THE INVENTION The present invention has been made as a result of intensive studies to obtain a film adhesive excellent in low water absorption and heat resistance which can be bonded at a low temperature in a short time. Has been found, and the present invention has been achieved.

[0006]

SUMMARY OF THE INVENTION The present invention provides a film adhesive containing a polyimide resin having a specific structure as a main component of an adhesive,
And its manufacturing method.

The polyimide resin of the present invention comprises a mole of 4,4'-oxydiphthalic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride and 3,3', 4,4 One or two kinds of tetracarboxylic dianhydrides (bmol) selected from the group of '-benzophenonetetracarboxylic dianhydride are used as an acid component, and 2,2-bis (4- (4-aminophenoxy) phenyl) C, moles of propane, and d moles of one or two kinds of diamines selected from the group of 1,3-bis (3-aminophenoxy) benzene and dimethylphenylenediamine, and α, ω-bis (3-aminopropyl) poly 3 moles of dimethylsiloxane
And the four components are amine components, and the molar ratios of a, b, c, d, and e are a / (a + b) ≧ 0.6 and b / (a + b) ≦ 0.
4, a polyimide resin soluble in an organic solvent in which both components are reacted at a ratio of 0.05 ≦ e / (c + d + e) ≦ 0.5 to form an imide ring closure, and the molecular terminal of the polyimide resin is represented by the general formula (1). End-capped with f mol of the acid anhydride represented or g mol of the aromatic amine represented by the formula (2), and the molar ratio of a, b, c, d, e, f, g is a /
(A + b + 0.5f) ≧ 0.6, b / (a + b + 0.5f) ≦
0.4, 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) ≦ 0.5, and either f or g is a polyimide resin that is soluble in an organic solvent in which imide is closed by reacting both components at a ratio of 0.

Embedded image (Where X is

Embedded image At least one group selected from

Embedded image (Wherein, Y is a hydrogen atom or at least one group selected from methyl, ethyl, propyl, butyl, phenyl, methoxy, ethoxy, propoxy, butoxy, or 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).

Embedded image

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

The α, ω-bis (3-aminopropyl) polydimethylsiloxane represented by the formula (3) is preferably such that n = 0 to 10, and particularly when the value of n is in the range of 4 to 10, the glass transition temperature, It is preferable from the viewpoint of adhesiveness and heat resistance. It is preferable to use a blend of n = 0 and the above n = 4 to 10 particularly in applications where importance is attached to adhesiveness.

Other acid anhydrides and diamines used in the production of polyimides, for example, 4,4'-oxydiphthalic dianhydride, pyromellitic anhydride, 3,3 ', 4,4'-diphenylsulfonetetracarboxylic acid Dianhydride, 2,2-bis (4- (4-aminophenoxy) phenyl) hexafluoropropane (B
APPF), 2,2-bis (4-aminophenoxy) hexafluoropropane (BAPF), bis-4- (4-aminophenoxy) phenylsulfone (BAPS), bis-4- (3-aminophenoxy) phenylsulfone ( BAPSM) or the like can be added in a small amount as long as the properties are not impaired.

It is important that the ratio of each component is within the above range. If α, ω-bis (3-aminopropyl) polydimethylsiloxane is less than 5 mol% of the total amine components, low moisture absorption characteristics are obtained. When it does not appear and exceeds 50 mol%, the glass transition temperature is remarkably lowered, and there is a problem in heat resistance. The molar ratio of 2,2-bis (4- (4-aminophenoxy) phenyl) propane is preferably in the range of 10 mol% to 90 mol% of the total amine component, And heat resistance.

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

By controlling the molecular weight by end-capping the molecular terminals of the polyimide resin, it is possible to obtain a melt viscosity suitable for adhesion to an adherend, to improve wettability and to increase adhesive strength. It is important that the amount ratio of the acid anhydride or the aromatic amine as the endcapping agent is within the above range, and if it is less than 1 mol%, the molecular weight becomes too high and may not be dissolved in the low boiling point solvent, In applications where adhesion is important, wettability deteriorates due to an increase in melt viscosity, which is not preferable. On the other hand, if it exceeds 5 mol%, the molecular weight is remarkably reduced, and there is a problem in heat resistance.

The end capping agent is represented by the general formula (1)
And an aromatic amine represented by the general formula (2). Examples of acid anhydrides include phthalic anhydride, maleic anhydride, and nadic anhydride; and aromatic amines include p-methylaniline, p-methoxyaniline,
p-phenoxyaniline and the like are used.

The equivalent ratio between the acid component and the amine component in the polycondensation reaction is an important factor that determines the molecular weight of the resulting polyamic acid. It is well known that there is a correlation between the molecular weight and physical properties of a polymer, especially the number average molecular weight and mechanical properties. The higher the number average molecular weight, the better the mechanical properties. Therefore, in order to obtain practically excellent strength, it is necessary to have a high molecular weight to some extent. In the present invention,
When the equivalent ratio r between the acid component and the amine component is 0.900 ≦ r ≦ 1.06, more preferably 0.975 ≦
It is preferable that r ≦ 1.06. Here, r = [equivalent number of all acid components] / [equivalent number of all amine components]. r is 0.
If the molecular weight is less than 900, the molecular weight is low and brittle, so that the adhesive strength is weak. If it exceeds 1.06, unreacted carboxylic acid may be decarbonated during heating to cause gas generation and foaming, which may be undesirable.

The reaction between the tetracarboxylic dianhydride and the diamine is carried out in a polar aprotic solvent by a known method. The aprotic polar solvent is N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMA
C), N-methyl-2-pyrrolidone (NMP), tetrahydrofuran (THF), diglyme, cyclohexanone,
And 1,4-dioxane. 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. This is because if the amount of the nonpolar solvent is 30% by weight or more, the dissolving power of the solvent may be reduced and polyamic acid may be precipitated. The reaction between the tetracarboxylic dianhydride and the diamine is carried out by dissolving the well-dried diamine component in the above-mentioned reaction solvent that has been dehydrated and purified, and adding thereto the ring-closing rate of 98%, more preferably 99% or more. The reaction is allowed to proceed by adding the anhydride.

The polyamic acid solution thus obtained is subsequently heat-dehydrated and cyclized in an organic solvent to give imidized polyimide. Since the water generated by the imidization reaction interferes with the ring closure reaction, an organic solvent incompatible with water is added to the system and azeotroped, and the system is removed from the system using a device such as a Dean-Stark tube. To be discharged. Dichlorobenzene is known as an organic solvent incompatible with water,
For the purpose of electronics, the above-mentioned aromatic hydrocarbon is preferably used because there is a possibility that a chlorine component may be mixed.
Further, it does not prevent the use of compounds such as acetic anhydride, β-picoline, and pyridine as a catalyst for the imidization reaction.

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

In the present invention, the obtained polyimide solution can be used as it is as a coating varnish. Also,
The polyimide solution can be put into a poor solvent to reprecipitate and precipitate the polyimide resin, remove unreacted monomers, purify, and dry to use as a solid polyimide resin. In applications that dislike the high-temperature process, or particularly in applications where impurities or foreign matter becomes a problem, it is preferable to dissolve again in an organic solvent to obtain a filtration and purification varnish. The solvent used at this time can be selected from solvents 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. 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 imidation ratio is low, imidization occurs due to heat at the time of bonding and water is generated, which is not preferable. Therefore, it is necessary that the imidation ratio be 95% or more, more preferably 98% or more.

In the present invention, the obtained polyimide solution may be applied to a support as it is, but the polyimide solution is poured into a poor solvent to reprecipitate the polyimide resin to remove unreacted monomers and purify. Is preferred. Purification,
The filtered and dried polyimide resin is again dissolved in an organic solvent to form a varnish. The solvent used at this time may be the same as the reaction solvent, but considering the workability of the coating and drying step, the boiling point is low,
It is preferable to select a solvent having a boiling point of 180 ° C. or less. Examples of the solvent at 180 ° C. or lower include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone and cyclohexanone as ketone solvents and 1,4-dioxane, tetrahydrofuran and diglyme as ether solvents. These solvents may be used alone or in combination of two or more. Amide-based solvents N, N-dimethylformamide and N, N-dimethylacetamide dissolve the polyimide resin of the present invention well at a boiling point of 180 ° C. or less, but strong interaction with polyimide requires a high temperature of 250 ° C. or more for drying. It is not preferable to use the varnish because it needs to be used and the film is whitened at the time of varnish application because of high hygroscopicity.

Various additives such as a smoothing agent, a leveling agent, and a defoaming agent for improving surface smoothness can be added to the polyimide resin varnish as needed. In addition, an aromatic hydrocarbon-based solvent can be used within a range in which the solvent is uniformly dissolved in order to adjust the evaporation rate of the solvent. In order to form a film adhesive, a polyimide resin varnish is cast and formed into a film, which is used alone or integrally with a film support.

For the casting of the polyimide resin varnish, an apparatus in which a coating apparatus such as a flow coater or a roll coater is combined with a hot air drying oven can be used. After the polyimide resin varnish is applied to the support, it is guided to a hot air drying oven and dried at a temperature and air volume sufficient to evaporate the solvent of the varnish. When used as a single film, the film is peeled off from the support. When the support is used integrally, the film is used while being attached to one or both surfaces 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 cutting into a predetermined shape and bonding by thermocompression bonding with a heated heat block.

[0025]

The film adhesive of the present invention is characterized by using a completely imidized polyimide resin having a specific structure which is soluble in a low boiling point organic solvent as a main component. The polyimide resin of the adhesive can achieve an extremely low ionic impurity level by reprecipitation purification, and almost completely eliminate the gas generated during heating by combining it with imidization using a solvent with a low boiling point. Can be.

Further, it is excellent in low water absorption and heat resistance, and can be bonded in a very short time as compared with a thermosetting adhesive accompanied by a chemical reaction. By processing into a tape shape, bonding workability and dimensional accuracy of the bonded portion can be improved. Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples.

[0027]

【Example】

(Example 1) Dehydrated and purified NMP755 was placed in a four-necked flask equipped with a dry nitrogen gas inlet tube, a cooler, a thermometer, and a stirrer.
g and stir vigorously for 10 minutes while flowing nitrogen gas. Next, 77.9978 g (0.190 mol) of 2,2-bis (4- (4-aminophenoxy) phenyl) propane (BAPP) and 10.8957 g (0.080 mol) of 2,5-dimethyl-p-phenylenediamine (DPX)
Mol), 100.4400 g of α, ω-bis (3-aminopropyl) polydimethylsiloxane (APPS) (average molecular weight 837, 0.1
20 mol), heat the system to 60 ° C, and stir until uniform. After dissolving uniformly, the system was cooled to 5 ° C. in an ice water bath, and 74.4533 g of 4,4′-oxydiphthalic dianhydride (0.240
Mol) and 47.0752 g (0.160 mol) of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride were added in the form of a powder over 15 minutes, and then stirring was continued for 3 hours. During this time, the flask was kept at 5 ° C. Then, p-phenoxyaniline (PP
A) 3.7046 g (0.020 mol) was added and stirring was continued for an additional hour.

After that, remove the nitrogen gas inlet pipe and the cooler,
A Dean-Stark tube filled with xylene was attached to the flask, and 188 g of toluene was added to the system. The system was heated to 175 ° C. instead of an oil bath, and the generated water was removed from the system. After heating for 4 hours, no water was generated from the system. After cooling, the reaction solution was poured into a large amount of methanol to precipitate a polyimide resin. After filtering the solids, 80
After drying under reduced pressure at 12 ° C. for 12 hours to remove the solvent, 284.99 g (yield 90.6
%) Of a solid resin was obtained. The infrared absorption spectrum was measured by the KBr tablet method.
μm absorption, but 6.06 μm
No absorption could be recognized, confirming that this resin was almost 100% imidized. At this time, the molar ratios of the acid and the amine were a / (a + b) = 0.6 and b /
(A + b) = 0.4, e / (c + d + e + 0.5 g) = 0.3
It is.

The polyimide resin thus obtained is dissolved in cyclohexanone / toluene (90/10 w / w%),
A polyimide resin varnish having a solid content of 25% was prepared. This varnish is applied to a polyimide film (trade name: Upilex SGA, thickness 50 μm, Ube Industries, Ltd.) using a reverse roll coater.
Co., Ltd.) to obtain an adhesive tape having an adhesive layer thickness of 30 μm. The drying temperature was a maximum of 185 ° C. and the drying time was 6 minutes. This adhesive tape was hot pressed on a 35 μm copper foil to produce a test piece. The copper foil was thermocompression-bonded to the treated surface at 250 ° C. for 2 seconds, annealed at 250 ° C. for 30 seconds after releasing the pressure. The pressure on the bonding surface is calculated from the gauge pressure and the bonding area.
gf / cm ² . The 180 degree peel strength of this specimen is 2.75
kgf / cm, showing excellent adhesive strength. In the fractured surface, the adhesive resin layer was cohesively broken and no foaming was observed.

Example 2 A varnish of Example 1 was applied to a biaxially stretched polyester film (trade name: Diafoil, thickness: 50 μm).
m, manufactured by Mitsubishi Rayon Co., Ltd.), drying temperature is up to 18
The drying time was 6 minutes at 5 ° C. After drying, the film was peeled off from the polyester film to obtain a 30 μm thick single-layer film without a support. Peeling was easy and there was no particular problem. Example 1
Table 1 shows the results of adhesion to the glossy surface of the copper foil in the same manner as described above.

Examples 3 to 5 A reaction was carried out in the same manner as in Example 1 to obtain a soluble polyimide resin. Table 1 shows the evaluation results obtained for these polyimide resins. 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, BPDA is 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, and BTDA is 4,4 '-Benzophenonetetracarboxylic dianhydride, PA is phthalic anhydride, BAPP is 2,2-bis (4- (4-aminophenoxy) phenyl) propane, APB is 1,3-bis (3-amino (Phenoxy) benzene, DPX is 2,5-dimethyl-p-phenylenediamine, APPS is α, ω-bis (3-aminopropyl) polydimethylsiloxane, and PPA is p-phenoxyaniline. .

The numerical values of the blending are the blending equivalent ratio of each component, and the water absorption is 168% under the environment of 85 ° C. and 85% RH.
The saturated water absorption after standing for a period of time (HH-168 treatment)
The generated moisture is a value obtained by quantifying the gas generated when heated at 250 ° C. for 15 minutes by the GC-MS method, and the water content is determined by the Karl Fischer method. S in the column of solubility indicates that the compound is dissolved in the corresponding solvent.

(Comparative Example 1) According to the composition shown in Table 2, the reaction was carried out under the same conditions as in Example 1 to obtain a polyimide resin. An attempt was made to dissolve this resin in cyclohexanone, but the resin was in a swollen gel state and could not be completely dissolved. In addition, the same condition was applied to DMF and DMAC, and a resin varnish could not be prepared. So NMP
To prepare a varnish, and applied to a polyimide resin to obtain a tape. At a drying temperature of 180 ° C., even after heating for 30 minutes, a weight loss of about 5.8% was observed at 200 to 250 ° C. by thermogravimetric analysis.
This is due to evaporation of the residual solvent NMP. 250 ℃ 3
Although the thermogravimetric loss was not observed after drying for 0 minutes, it was impossible to produce a double-sided coated tape because the temperature greatly exceeded the glass transition temperature of the resin.

Comparative Example 2 The varnish of Comparative Example 1 was used in Example 2.
It was attempted to prepare a film without a support by coating on a polyester film in the same manner as above, but at a temperature exceeding 200 ° C, the polyester film of the support shrunk and was impossible, and at a drying temperature of 200 ° C or less, The solvent NMP could not be skipped, and again a film could not be made.

(Comparative Examples 3 and 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]

In Table 2, PMDA stands for pyromellitic anhydride, and PPDA for p-phenylenediamine.

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 moisture absorption.

[0041]

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 at the time of heating is extremely low, it is extremely useful industrially as a microelectronic material and a semiconductor packaging material.

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08G 73/00-73/26 C09J 179/00-179/08 C08L 79/00-79/08 CA (STN)

Claims (4)

(57) [Claims] 1. An amol of 4,4'-oxydiphthalic dianhydride and 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride
One or two kinds of tetracarboxylic dianhydrides (bmol) selected from the group of 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride are used as an acid component, and 2,2-bis (4- (4-aminophenoxy) phenyl) propane (c mol), 1,3-bis (3-aminophenoxy) benzene and one or two kinds of diamines selected from the group consisting of dimethylphenylenediamine, and α, ω- 3 to 4 components consisting of bis (3-aminopropyl) polydimethylsiloxane e mol as an amine component, and the molar ratio of a, b, c, d and e is a / (a + b) ≧
0.6, b / (a + b) ≦ 0.4, and 0.05 ≦ e / (c +
d + e) A film adhesive mainly composed of a polyimide resin which is soluble in an organic solvent in which imides are closed by reacting both components at a ratio of 0.5 or less. 2. An amol of 4,4'-oxydiphthalic dianhydride and 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride
One or two kinds of tetracarboxylic dianhydrides (bmol) selected from the group of 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride are used as an acid component, and 2,2-bis (4- (4-aminophenoxy) phenyl) propane (c mol), 1,3-bis (3-aminophenoxy) benzene and one or two kinds of diamines selected from the group of dimethylphenylenediamine, and α, ω- The molecular terminal of a polyimide resin having 3 to 4 components consisting of e mol of bis (3-aminopropyl) polydimethylsiloxane as an amine component is reacted with f mol of an acid anhydride represented by the general formula (1) or (2) A), b, c, d,
The molar ratio of e, f, and g is a / (a + b + 0.5f) ≧ 0.6,
b / (a + b + 0.5f) ≦ 0.4, 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) ≤0.5
And a film adhesive mainly composed of a polyimide resin soluble in an organic solvent in which imide is closed by reacting both components at a ratio where either f or g is 0. Embedded image (Wherein X is At least one group selected from the group consisting of: (Wherein, Y is a hydrogen atom or at least one group selected from methyl, ethyl, propyl, butyl, phenyl, methoxy, ethoxy, propoxy, butoxy, or phenoxy groups) 3. The method according to claim 1, wherein an organic solvent solution of a polyimide resin in which the imide ring-closing reaction is completed by heating and dehydrating the polyamic acid in an organic solvent is cast on one or both surfaces of the support. Manufacturing method of film adhesive. 4. The film adhesive according to claim 1, wherein the film adhesive is cast on a support using an organic solvent having a boiling point of 180 ° C. or lower, dried, and then peeled from the support. Production method.