JPH05117598A - Film adhesive having high thermal conductivity and bondable by hot melt bonding - Google Patents

Abstract

PURPOSE:To obtain the subject adhesive keeping high adhesiveness even at a molten solder temperature by using a polyimide obtained by reacting 1,3-bis(3- aminophenoxy)benzene, a silicone diamine, etc., and an acid dianhydride and a filler having a specific thermal conductivity as essential components. CONSTITUTION:The objective adhesive is produced by reacting an amine component consisting of (A) 1,3-bis(3-aminophenoxy)benzene, (B) a silicone diamine of formula (R1 and R2 are bivalent 1-5C aliphatic group or >=6C aromatic group; R3 and R4 are univalent aliphatic group or aromatic group; (n) is 1-100) and (C) other diamine component with (D) an acid dianhydride component (at least one of the components A and B is used as essential component) at a molar ratio (A+B)/(A+B+C+D) of 0.3-0.55 and (A+B+C)/D of 0.8-1.3 to obtain a polyimide resin having an imidation degree of >=80%, compounding the obtained polyimide resin with 30-900wt.% (based on the resin) of a filler having a thermal conductivity of >=5.0[W/m.k)] and forming the mixture in the form of a film.

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 excellent thermal conductivity and heat resistance and can be used by thermocompression bonding.

[0002]

2. Description of the Related Art Heretofore, some heat-resistant thermocompression-bondable film adhesives have been known. For example, Japanese Patent Laid-Open No. 1-2822
No. 83, a polyamide-imide or polyamide hot-melt adhesive, JP-A-58-157190, JP-A-58-157190, a method for manufacturing a flexible printed circuit board using a polyimide adhesive, JP-A-62-235382 and JP-A-62-235383 describes a thermosetting polyimide film adhesive. 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. .. The standard conditions for thermocompression bonding of film adhesives described in other publications are 275 ° C, 50kgf / cm ² and 30 minutes, which require electronic components sensitive to heat and pressure and mass productivity. It could not be said that it is necessarily advantageous as a film adhesive for other applications.

In recent years, as the degree of integration of semiconductor integrated circuits has increased, the use of heat sinks or heat radiating fins has been studied as a method for heat dissipation of ICs. There is a need for adhesives with high thermal conductivity. These high thermal conductivity adhesives have a film-like shape that can be thermocompression bonded than liquid adhesives that easily cause voids and bubbles to get inside because voids such as voids are present in the bonded area. Adhesives are said to be preferred. However, until now, no film-like adhesive has satisfied all of high thermal conductivity, high adhesiveness, heat resistance, workability and the like.

On the other hand, conventionally used epoxy resins,
Phenolic and acrylic adhesives can be used at relatively low temperatures,
Although it has an advantage that it can be thermocompression-bonded at a low pressure, it needs to be cured to some extent because it is a thermosetting type. Although a thermoplastic resin is often used as a hot melt adhesive, it has a drawback of poor heat resistance.

[0005]

DISCLOSURE OF THE INVENTION The present inventors have earnestly studied to obtain a highly heat-conductive film adhesive having excellent heat resistance and capable of thermocompression bonding at low temperature, low pressure and short time, and as a result,
It was found that an adhesive obtained by uniformly dispersing a filler having a certain thermal conductivity or more into a polyimide resin having a specific structure to form a film can achieve the above-mentioned target, and thus completed the present invention. It is an object of the invention to provide a film-like adhesive having both thermal conductivity, heat resistance and thermocompression bonding workability.

[0006]

The present invention provides 1,3-bis (3-
Aminophenoxy) benzene A mole and silicone diamine B mole represented by the formula (1)

[0007]

[Chemical 1]

And an amine component containing C moles of other diamine components and D moles of acid dianhydride components, with at least one of 1,3-bis (3-aminophenoxy) benzene and silicone diamine as an essential component. , (A + B) / (A
+ B + C + D) is 0.3 to 0.55, (A + B + C) / D is 0.8
-React in the range of 1.3, at least 80% or more of the polyimide resin is imidized, and 30 to 900w with respect to the resin
A film-like adhesive capable of thermocompression bonding, which comprises a filler having a t% thermal conductivity of 5.0 [W / (m · K)] or more.

The acid dianhydride used in the present invention is
Although not particularly limited, for example, pyromellitic dianhydride, 3,3 ', 4,4'-benzophenone tetracarboxylic acid dianhydride, 2,2', 3,3'-benzophenone Tetracarboxylic acid dianhydride, 2,3,3 ', 4'-benzophenone tetracarboxylic acid dianhydride, naphthalene-2,3,6,7-tetracarboxylic acid dianhydride, naphthalene-1,2,5, 6-tetracarboxylic dianhydride, naphthalene-1,2,4,5-tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, naphthalene-1,2,6 , 7-tetracarboxylic dianhydride,
4,8-Dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,
2,5,6-tetracarboxylic dianhydride, 4,8-dimethyl-1,2,
3,5,6,7-Hexahydronaphthalene-2,3,6,7-tetracarboxylic dianhydride, 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2 , 7-Dichloronaphthalene-1,
4,5,8-tetracarboxylic dianhydride, 2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 1,
4,5,8-Tetrachloronaphthalene-2,3,6,7-tetracarboxylic dianhydride, 3,3 ', 4,4'-diphenyltetracarboxylic dianhydride, 2,2', 3, 3'-diphenyltetracarboxylic dianhydride, 2,3,3 ', 4'-diphenyltetracarboxylic dianhydride, 3,3 ", 4,4" -p-terphenyltetracarboxylic dianhydride, 2,2 ", 3,3" -p-terphenyltetracarboxylic dianhydride, 2,3,3 ", 4" -p-terphenyltetracarboxylic dianhydride, 2,2-bis (2, 3-dicarboxyphenyl) -propane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -propane dianhydride, bis (2,3-dicarboxyphenyl) ether dianhydride, bis (2 , 3-Dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, bis (2,3-dicarboxyphenyl) sulfone dianhydride, bis (3,4-dicarboxy Phenyl) sulfone dianhydride, 1,1-bis (2,3-dicarbo (Xyphenyl) ethane dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane dianhydride, perylene-2,3,8,9-tetracarboxylic dianhydride, perylene-3,4,9 , 10-Tetracarboxylic acid dianhydride, perylene
-4,5,10,11-tetracarboxylic dianhydride, perylene-5,6,
11,12-Tetracarboxylic acid dianhydride, phenanthrene-1,
2,7,8-Tetracarboxylic acid dianhydride, phenanthrene-1,
2,6,7-Tetracarboxylic acid dianhydride, phenanthrene-1,
2,9,10-Tetracarboxylic acid dianhydride, cyclopentane-1,
2,3,4-tetracarboxylic dianhydride, pyrazine-2,3,5,6-
Tetracarboxylic acid dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic acid dianhydride, thiophene-2,3,4,5-tetracarboxylic acid dianhydride, 4,4'-oxydiphthalic acid dianhydride However, the present invention is not limited to these.

The diamine component used in the present invention is 1,3-bis (3-aminophenoxy) benzene (hereinafter referred to as AP
(Abbreviated as B), silicone diamine and other diamines. Other diamines are not particularly limited,
Specific examples are 3,3'-dimethyl-4,4'-diaminobiphenyl, 4,6-dimethyl-m-phenylenediamine, 2,5
-Dimethyl-p-phenylenediamine, 2,4-diaminomesitylene, 4,4'-methylenedi-o-toluidine, 4,4'-methylenedi-2,6-xylidine, 4,4'-methylene-2,6- Diethylaniline, 2,4-toluenediamine, m-phenylene-diamine, p-phenylene-diamine, 4,4'-diamino-diphenylpropane, 3,3'-diamino-diphenylpropane, 4,4 '
-Diamino-diphenylethane, 3,3'-diamino-diphenylethane, 4,4'-diamino-diphenylmethane, 3,3'-diamino-diphenylmethane, 4,4'-diamino-diphenylsulfide, 3,3'-diamino -Diphenyl sulfide, 4,
4'-diamino-diphenyl sulfone, 3,3'-diamino-diphenyl sulfone, 4,4'-diamino-diphenyl ether,
3,3'-diamino-diphenyl ether, benzidine, 3,3 '
-Diamino-biphenyl, 3,3'-dimethyl-4,4'-diamino-
Biphenyl, 3,3'-dimethoxy-benzidine, 4,4 "-diamino-p-terphenyl, 3,3" -diamino-p-terphenyl, bis (p-amino-cyclohexyl) methane, bis (p-β
-Amino-t-butylphenyl) ether, bis (p-β-methyl-δ-aminopentyl) benzene, p-bis (2-methyl-4-)
Amino-pentyl) benzene, p-bis (1,1-dimethyl-5-amino-pentyl) benzene, 1,5-diamino-naphthalene,
2,6-diamino-naphthalene, 2,4-bis (β-amino-t-butyl) toluene, 2,4-diamino-toluene, m-xylene-2,5
-Diamine, p-xylene-2,5-diamine, m-xylylene-
Diamine, p-xylylene-diamine, 2,6-diamino-pyridine, 2,5-diamino-pyridine, 2,5-diamino-1,3,4-oxadiazole, 1,4-diamino-cyclohexane, piperazine, Methylene-diamine, ethylene-diamine, propylene-diamine, 2,2-dimethyl-propylene-diamine, tetramethylene-diamine, pentamethylene-diamine, hexamethylene-diamine, 2,5-dimethyl-hexamethylene-diamine, 3- Methoxy-hexamethylene-diamine, heptamethylene-diamine, 2,5-dimethyl-heptamethylene-diamine, 3-methyl-heptamethylene-diamine, 4,4-dimethyl-heptamethylene-diamine, octamethylene-diamine, nonamethylene- Diamine, 5-methyl-
Nonamethylene-diamine, 2,5-dimethyl-nonamethylene-
Diamine, decamethylene-diamine, 1,10-diamino-1,1
0-dimethyl-decane, 2,11-diamino-dodecane, 1,12-diamino-octadecane, 2,12-diamino-octadecane,
2,17-diamino-aicosan and the like can be mentioned.

The reaction between the acid dianhydride and the diamine in the present invention can be carried out by a known method. Either the acid dianhydride component or the diamine component is dissolved or suspended in an organic solvent in advance, and the other component is gradually added in a powder or liquid state or in a state of being dissolved in the organic solvent. Since the reaction is exothermic, the temperature of the reaction system is preferably maintained near room temperature while cooling.

It is desirable that the molar ratio (A + B + C) / D of the diamine component and the acid dianhydride component is in the vicinity of the equivalent, particularly in the range of 0.8 to 1.3. If either one becomes too large,
It is not preferable because the molecular weight does not increase and the heat resistance and mechanical properties deteriorate. After reacting at around room temperature to synthesize polyamic acid, imidization can be carried out by a known method such as heating or using an acetic anhydride / pyridine catalyst. The imidization ratio is preferably at least 80% or more. If the imidization ratio is lower than 80%, imidization progresses when the film is formed later and thermocompression bonding is performed, water is generated, and voids are caused, resulting in a decrease in adhesive strength, which is not preferable.

The value of (A + B) / (A + B + C + D) is
It is necessary to be 0.3 to 0.55, and if it is less than 0.3, the heat melting property will be reduced, and thermocompression bonding conditions of at least 300 ° C. or higher or 50 kgf / cm ² or higher are required, which is preferable in terms of mass productivity. Absent. If it is 0.3 or more, thermocompression bonding can be performed at a temperature of 250 ° C. or less and a pressure of 20 kgf / cm ² or less in a short time within 10 minutes, and good adhesive strength can be achieved.

In the present invention, it is necessary that at least either APB or silicone diamine is contained as an essential component. Due to the structural characteristics of APB and silicone diamine, when at least one of them is contained in the polyimide so as to satisfy the above-mentioned molar ratio, it has excellent heat melting property, good adhesive strength, and heat resistance. It is possible to obtain a film-like adhesive having an excellent balance with

The organic solvent used in the present invention is not particularly limited, but one solvent or a mixed solvent of two or more solvents may be used as long as it can be uniformly dissolved. Typical solvents of this type are N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylformamide, N, N-diethylacetamide, N, N-dimethylmethoxyacetamide, dimethylsulfoxide, Hexamethylphosphoramide, N-methyl
-2-pyrrolidone, pyridine, dimethyl sulfone, tetramethyl sulfone, dimethyl tetramethylene sulfone, γ
-Butyrolactone, diglyme, tetrahydrofuran,
There are methylene chloride, dioxane, cyclohexanone, and the like, and a poor solvent can be used as a volatilization regulator, a film smoothing agent, etc. within a range in which it can be uniformly dissolved.

If the high thermal conductivity filler used in the present invention has a thermal conductivity of 5.0 [W / (m · K)] or more, sufficient thermal conductivity can be obtained by uniformly dispersing it in the film adhesive. Therefore, the type is not particularly limited, but when conductivity is not required, insulating and semiconducting ceramics mainly having phonon conduction are preferable. When the thermal conductivity is less than 5.0 [W / (m · K)], sufficient thermal conductivity cannot be obtained when uniformly dispersed in the film-like adhesive layer, which is not preferable.

Examples of the high thermal conductive filler used in the present invention include Al ₂ O ₃ , BeO, MgO, SiC, TiC, TiN and Si ₃ N.
₄ , AlN, BN, ZrB ₂ , MoSi ₂ , diamond and the like, which may be used alone or in combination of two or more, but are not particularly limited thereto. As the shape, a flake shape, a dendritic shape, a spherical shape, or the like is used. You may mix and use the thing of a different particle size. The particle size for obtaining the required characteristics is preferably 0.01 to 50 μm. The amount of filler in the film adhesive of the present invention is 30 to 900w with respect to the resin.
A ratio of t% is desirable. If it is less than 30 wt%, sufficient thermal conductivity cannot be obtained, which is not preferable, and if it exceeds 900 wt%, the adhesive strength is lowered, which is not preferable.

The method of using the thermocompression-bondable high-heat-conductive film adhesive of the present invention is not particularly limited, but a filler is usually added to a sufficiently imidized varnish, and a mixer, three After uniformly dispersing using a roll, etc., dilute it if necessary and adjust the viscosity, apply it to a substrate with excellent releasability such as Teflon, then volatilize the solvent by heat treatment to form a film Then, it is peeled from the base material to obtain a film containing a high thermal conductive filler. This is sandwiched between the adherends and then thermocompression bonded. Alternatively, it may be applied on the adherend in advance and then subjected to heat treatment to sufficiently volatilize the solvent, and then thermocompression bonding is performed together with one of the adherends.

If desired, various additives can be added to the polyimide resin which is the base resin of the adhesive of the present invention. For example, a surface smoothing agent when applied to a substrate,
Leveling agents to improve wettability and various surfactants,
It is an additive such as a silane coupling agent and various crosslinking agents for increasing the heat resistance of the adhesive after thermocompression bonding. These additives can be used in an amount that does not impair the properties of the film adhesive.

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0021]

【Example】

(Example 1) In a four-neck separable flask equipped with a thermometer, a stirrer, a raw material charging port, and a dry nitrogen gas inlet tube, 1,
3-bis (3-aminophenoxy) benzene (APB) 14.62
g (0.05 mol) and silicone diamine of the following formula (hereinafter abbreviated as G9) 42.09 g (0.05 mol)

[0022]

[Chemical 2]

300 g of N-methyl-2-pyrrolidone (NM
P) and dissolved in 4,4'-oxydiphthalic acid dianhydride (O
31.02 g (0.1 mol) of DPA was gradually added in powder form over 30 minutes, and stirring was continued for 2 hours. Dry nitrogen gas was kept flowing during this time, and the system was kept at 20 ° C. for the whole reaction during the reaction by cooling with an ice bath before adding ODPA.

Then, 60 g of xylene was added to this system,
Remove the dry nitrogen inlet tube and replace it with a Dean Starch reflux condenser, remove the ice bath and heat in an oil bath to raise the system temperature. Continue heating while removing water generated by imidization from the system by azeotropic distillation with toluene.
The reaction was terminated 5 hours after the imidization proceeded at 0 to 160 ° C. and no more water was generated. This polyimide varnish was added dropwise to 30 liters of methanol with stirring for 1 hour to precipitate the resin, and the solid content was collected by filtration, and then dried in a vacuum dryer under reduced pressure at 120 ° C for 5 hours. Let The FT-IR spectrum of the polyimide resin thus obtained was measured, and the imidization ratio was determined from the absorption based on the amide bond before imidization appearing at 1650 cm ^-1 , and the absorption based on the imide ring appearing at 1780 cm ^-1. As a result, it was found that it was 100% imidized.

This polyimide resin was dissolved in diethylene glycol dimethyl ether (diglyme) to give a concentration of 10
Adjusted to%. 120 wt% of boron nitride having an average particle size of 2 μm was added to this varnish with respect to the resin content and mixed using a three-roll to obtain a paste. This paste is cast on a Teflon plate whose surface has been polished using an applicator, and the solvent is volatilized by heating it at 120 ° C for 5 hours in a dryer, and peeled off from the Teflon substrate.
A 25 μm film was made. From this film, 3mm x
Cut out a 3.5 mm square size and use a copper lead frame and 3
It is sandwiched between silicon chips of size mm × 3.5 mm square, 230
Apply a load of 500g on the hot plate at ℃ (about 4.76kgf
/ Cm ² ), after thermocompression bonding for 10 seconds, it was cooled to room temperature and the shear strength was measured with a push-pull gauge. At a value of 10 kgf or more, the silicon chip broke and accurate shear strength could not be obtained. , Was firmly adhered. Then 260
When the same adhesive sample was placed on a hot plate at ℃ for 10 seconds and the shear strength was measured, a strength of 1.3 kgf was obtained. The mode of destruction was cohesive failure, and part of the film remained on both the lead frame and the chip. No void was observed in the film. The thermal conductivity and volume resistivity of this film were measured and found to be 3.
It was 4 [W / (m · K)], 1 × 10 ¹⁵ [Ω-cm], and it was confirmed that it has high thermal conductivity and excellent insulating properties.

(Example 2) ODP was used as an acid anhydride component.
A 18.61 g (0.06 mol), 3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride (BTDA) 12.89 g (0.04 mol) and as a diamine component, APB 14.62 g (0.05 mol), G9 16.84 g (0.02 mol), 2,4-diaminotoluene (hereinafter abbreviated as TDA) 4.89 g (0.04 mol) except that the polyimide resin was obtained by the same method as in Example 1 and the imidation ratio was measured. %Met. This resin is treated with diglyme and butyl cellosolve acetate (B
CA) was dissolved in a 1: 1 mixed solvent to adjust the concentration to 15%.

To this varnish, 150 wt% of Al ₂ O ₃ having an average particle size of 3 μm was added with respect to the resin content and mixed by a three-roll to obtain a paste. This paste is cast on a Teflon plate whose surface has been polished using an applicator, and then 120
The solvent was volatilized by heating at 5 ° C. for 5 hours and peeled off from the Teflon substrate to form a film having a thickness of 25 μm. A 3mm x 3.5mm square piece is cut out from this film, sandwiched between a copper lead frame and a 3mm x 3.5mm square silicon chip, and a 500g load is applied for 10 seconds on a 300 ° C hot plate. did. When the shear strength was measured at room temperature, the silicon chip broke at 10 kgf or more. Next, when a similar adhesive sample was placed on a hot plate at 260 ° C for 10 seconds and shear strength was measured, 5.
It was 1 kgf. No void was observed on the surface of the adhesive film. The thermal conductivity and volume resistivity of this film were measured to be 1.9 [W / (mK)] and 1 × 10 ¹⁶ [Ω-c, respectively]
m], and it was confirmed that it has high thermal conductivity and excellent insulation.

(Examples 3 to 5 and Comparative Examples 1 to 5) Except for the composition of the polyimide resin, the imidization time, the kind of the high thermal conductive filler, and the addition amount, the same procedure as in Example 1 was carried out. I got the result.

[0029]

[Table 1]

As in Examples 1 and 2 and Examples 3 to 5 in Table 1, APB and silicone diamine accounted for 0.3 to 0.55 in terms of the number of moles of the total resin composition, and the acid anhydride and the diamine. Thermal conductivity of 5.0 [W / (m · K)] using a polyimide with a molar ratio in the range of 0.8 to 1.3 and an imidization ratio of 80% or more.
The film obtained by uniformly dispersing the above fillers,
At a relatively low temperature of 250 ° C or less, and at a relatively low pressure of 5 kgf / cm ^2, a strong adhesive strength can be obtained under a thermocompression bonding condition of a short time of 10 seconds, and even at a high temperature of 260 ° C, 1 kgf or more. It had adhesive strength. The obtained adhesive layer also had a thermal conductivity of 1.0 [W / (m · K)] or higher and high thermal conductivity, and had an insulating property of 10 ¹⁰ [Ω-cm] or higher in terms of volume resistivity.

On the other hand, as in Comparative Example 1, the ratio of APB and silicone diamine in the total resin composition is 0.
When it was less than 3, sufficient adhesive strength could not be obtained under the thermocompression bonding conditions of 250 ° C., 5 kgf / cm ² , and 10 seconds. As in Comparative Example 2, when the amount of the filler added was less than 30 wt% with respect to the resin content, sufficient thermal conductivity could not be obtained. On the contrary, as in Comparative Example 3, when the amount of the filler added exceeded 900 wt%, the relative amount of the resin as the adhesive component decreased, and sufficient adhesive strength could not be obtained. As in Comparative Example 4, the thermal conductivity was 5.
When a filler of 0 [W / (m · K)] or less was used, sufficient thermal conductivity could not be obtained. 80% imidization rate as in Comparative Example 5
If it is less than this, voids are generated on the film surface after thermocompression bonding, and thus sufficient adhesive strength cannot be obtained. As described above, good results could not be obtained except under the conditions of the present invention.

[0032]

EFFECTS OF THE INVENTION The thermocompression-bondable film adhesive of the present invention has excellent adhesiveness to metals such as copper and silicon and ceramics, and is sufficient not only at room temperature but also at solder melting temperature such as 260 ° C. It has excellent adhesive strength and excellent heat dissipation, and is excellent in heat resistance. Moreover, it is possible to obtain a heat-resistant film-like adhesive which is unprecedented and is advantageous in terms of mass productivity, which enables thermocompression bonding at low temperature, low pressure, and short time.

Claims (1)

[Claims] 1. A mole of 1,3-bis (3-aminophenoxy) benzene A and a silicone diamine B represented by the formula (1).
An amine component containing moles and C moles of another diamine component;
At least one of 1,3-bis (3-aminophenoxy) benzene and silicone diamine is an essential component of D dianhydride component D mol, and (A + B) / (A + B + C
+ D) is in the range of 0.3 to 0.55 and (A + B + C) / D is in the range of 0.8 to 1.3, and at least 80% or more of the polyimide resin is imidized, and the thermal conductivity of the resin is 30 to 900 wt% 5.0 [ W / (m · K)] or more, which is a thermocompression-bondable high-thermal-conductivity film adhesive. [Chemical 1]