JP2008208295A - Modified polyamide-imide resin, adhesive using the same, and printed circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive composition and an adhesive sheet capable of low-temperature adhesion, excellent in adhesion, heat-resistance, and migration-resistance under high temperature and high humidity conditions, and particularly useful for circuit boards, and to provide a printed circuit board using the same. <P>SOLUTION: Polyamide-imide is copolymerized with poly(acrylonitrile-butadiene) and dimer acid or polyester to prepare a modified polyamide-imide resin. The resultant modified polyamide-imide resin has a glass transition temperature of 120°C or higher, an inherent viscosity of 0.1 dl/g or more, and a tensile modulus of 1,500 MPa or less. Also disclosed are a heat-resistant adhesive prepared by blending a crosslinking agent with the resin, an adhesive sheet formed from the adhesive, and a printed circuit board using the sheet. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a novel modified polyamideimide resin, a heat-resistant adhesive using the same, and a printed circuit board.

Conventionally, as a heat-resistant adhesive, a material mainly composed of a polyimide resin or an epoxy resin has been used, but there are some problems when using these resins.
One of them is the compatibility between heat resistance and low-temperature adhesiveness. In general, since polyimide has excellent heat resistance, it requires strong equipment for bonding at high temperatures, and epoxy adhesives that can be bonded at low temperatures have a problem of poor heat resistance.
Several specific methods for achieving both the low-temperature adhesiveness and the heat resistance have been disclosed. For example, there are methods such as using a heat-resistant epoxy resin and a maleimide resin, but these resins are fragile due to their high curing density, and therefore their use is limited. In addition, Patent Document 1 shows that an epoxy resin is blended with a polyetherimide having a specific structure to achieve both low-temperature adhesion and heat resistance. If this is the case, an adhesive temperature of 200 ° C. is required, and it cannot be said that the adhesiveness is sufficiently low. Polyamideimide heat-resistant adhesives have also been proposed. For example, Patent Document 2 and Patent Document 3 disclose polyamideimides copolymerized with acrylonitrile-butadiene and adhesives for semiconductors using the same. And Patent Document 5 propose a polyamideimide copolymerized with dimer acid and an adhesive for semiconductors using the same, but the former is excellent in low-temperature adhesion and solder resistance, but is copper under high temperature and high humidity. The circuit portion of the foil has a drawback that it tends to cause migration by generating dendrites, and the latter has the disadvantage that the adhesiveness is insufficient due to the lack of flexibility of the resin.

JP-A-63-99280 Japanese Patent Laid-Open No. 11-21455 JP 2001-11421 A Japanese Patent Laid-Open No. 11-21454 JP 2001-11420 A

  It is an object of the present invention to provide an adhesive having both heat resistance, low-temperature adhesiveness and migration resistance, in particular, an adhesive useful for a printed circuit board and a sheet thereof, and a printed circuit board using them. It is.

In order to solve the above problems, the present inventor has intensively studied, studied, and finally achieved the present invention. That is, the present invention is as follows.
(1) A modified polyamideimide resin in which poly (acrylonitrile-butadiene) and dimer acid or polyester are copolymerized in polyamideimide, and the glass transition temperature of the modified polyamideimide resin is 120 ° C. or higher and the logarithmic viscosity is A modified polyamideimide resin having a tensile elastic modulus of not less than 0.1 dl / g and a tensile modulus of not more than 1500 MPa.
(2) The modified polyamideimide resin according to (1) above, wherein the modified polyamideimide resin is dissolved in one or more mixed solvents of ethanol, toluene, tetrahydrofuran, cyclohexanone, and cyclopentanone. .
(3) A heat-resistant adhesive in which one or more of a polyfunctional epoxy compound, a melamine compound, and an isocyanate compound is blended as a crosslinking agent in the modified polyamideimide resin according to (1) or (2).
(4) An adhesive sheet formed from the heat-resistant adhesive according to (3).
(5) A printed circuit board using the heat-resistant adhesive according to (3) or (4) or a sheet thereof.

  The modified polyamideimide resin of the present invention is excellent in heat resistance, low-temperature adhesiveness and migration resistance, and dissolves in a low boiling point solvent. Therefore, when using an adhesive obtained therefrom, it is excellent in workability and printed circuit. It is suitably used for a plate or the like.

The polyamideimide resin used in the present invention can be produced by a known method such as an acid chloride method or an isocyanate method.
In addition to trimellitic acid and its anhydride and chloride, pyromellitic acid, biphenyltetracarboxylic acid, biphenylsulfonetetracarboxylic acid, benzophenonetetracarboxylic acid, and biphenylethertetracarboxylic acid are used as acid components for the production of polyamideimide resin. Tetracarboxylic acids such as acids, ethylene glycol bis trimellitate and propylene glycol bis trimellitate and their anhydrides, oxalic acid, adipic acid, malonic acid, sebacic acid, azelaic acid, dodecanedicarboxylic acid, dicarboxypolybutadiene, dicarboxypoly (Acrylonitrile-butadiene), dicarboxylic acid poly (styrene-butadiene) aliphatic dicarboxylic acid, 1,4 cyclohexane dicarboxylic acid, 1,3 cyclohexane dicarboxylic acid, 4,4 ′ dicyclohex Examples include cycloaliphatic dicarboxylic acids such as silmethane dicarboxylic acid and dimer acid, and aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, diphenylsulfone dicarboxylic acid, diphenyl ether dicarboxylic acid, and naphthalenedicarboxylic acid. Trimellitic anhydride is most preferable from the viewpoints of properties, adhesiveness, solubility, and the like, and more preferably a part of which is replaced with dicarboxypoly (acrylonitrile-butadiene) and dimer acid.

  Diamines (diisocyanates) used for the production of polyamideimide resins include aliphatic diamines such as ethylenediamine, propylenediamine, and hexamethylenediamine, and their diisocyanates, 1,4 cyclohexanediamine, 1,3 cyclohexanediamine, isophorone diamine, 4,4. 'Alicyclic diamines such as dicyclohexylmethanediamine and their diisocyanates, m-phenylenediamine, p-phenylenediamine, 4,4'diaminodiphenylmethane, 4,4'diaminodiphenyl ether, 4,4'diaminodiphenylsulfone, benzidine, o -Aromatic diamines such as tolidine, 2,4tolylenediamine, 2,6tolylenediamine, xylylenediamine, diaminopoly (acrylonitrile-butadiene) and the like Include diisocyanates of heat resistance among these, adhesion, solubility, etc. from 4,4'-diaminodiphenylmethane (diisocyanate), isophorone diamine (diisocyanate) and diamino poly (acrylonitrile-butadiene) and the like are preferable.

  The modified polyamideimide resin of the present invention can be copolymerized with a diol component in addition to the above-mentioned acid component and diamine (diisocyanate) component. Examples of the diol component include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, tetota ethylene glycol, polytetraethylene glycol, polyester diol, and carbonate diol. Among these, adhesiveness and solubility To polyester diol are particularly preferable, and polyethylene glycol, polypropylene glycol, and polytetraethylene glycol are also preferable.

  The modified polyamideimide resin of the present invention is copolymerized with acrylonitrile-butadiene component and dimer acid or polyester in order to satisfy all of heat resistance, solder resistance, low-temperature adhesion and migration resistance when formed into a circuit board. It is necessary. In this case, the content of the acrylonitrile-butadiene component is 10 to 60% by weight, preferably 15 to 40% by weight, and the content of the dimer acid or polyester component is 5 to 60% by weight, preferably 10 to 10%, based on the whole polyamideimide resin. 40% by weight. If the acrylonitrile-butadiene component is 10% by weight or less, solder resistance, particularly lead-free solder resistance of 290 ° C. or more is insufficient, and if it is 60% by weight or more, migration resistance is lowered. If the dimer acid or polyester component is 5% by weight or less, the low-temperature adhesiveness is deteriorated, and if it is 60% by weight or more, the heat resistance and solder resistance are deteriorated.

The modified polyamideimide resin of the present invention is stirred in a polar solvent such as N, N′dimethylacetamide, N-methyl-2-pyrrolidone, N, N′dimethylformamide, and γ-butyrolactone while heating at 60 to 200 ° C. It can be manufactured easily.
Further, the polymerization solution can be used by dissolving it in a solvent immiscible with the polymerization solution, preferably acetone or water, removing the polymerization solvent, washing, drying and re-dissolving in another solvent. Examples of the solvent used for redissolving include alcohols such as methanol, ethanol and butanol, aromatic hydrocarbons such as toluene and xylene, ethers such as tetrahydrofuran and dioxane, and ketones such as cyclopentanone and cyclohexanone.

The application of the heat-resistant adhesive of the present invention is not particularly limited, but the most useful use is an adhesive for printed circuit boards, specifically, polyimide film, polyester film, glass-epoxy sheet, phenol resin sheet, etc. Adhesive for bonding copper foil or aluminum foil to insulating substrate, adhesive for coverlay film, adhesive for reinforcing part of circuit board with reinforcing plate, when mounting semiconductor chip directly on circuit board An adhesive etc. are mentioned.
In any case, the polyamide-imide resin used as the main component of this adhesive composition needs to satisfy low-temperature adhesiveness, heat resistance, and adhesive strength in order to cope with the recent increase in wiring density and lead-free solder orientation. For this purpose, the glass transition temperature is preferably 120 ° C. or higher, the logarithmic viscosity is 0.1 dl / g or higher, and the tensile elastic modulus is preferably 1500 MPa or lower. When the glass transition temperature is 120 ° C. or lower, the heat resistance is insufficient and the logarithmic viscosity is 0.1 dl / g or lower, or when the tensile elastic modulus is 1500 MPa or higher, the resin becomes brittle and the adhesive strength is insufficient.

  In the heat-resistant adhesive of the present invention, a crosslinking agent can be blended in order to improve low-temperature adhesiveness and adhesive strength within a range not impairing heat resistance. Although there is no restriction | limiting as a crosslinking agent, Although a bifunctional or more polyfunctional epoxy compound, a melamine compound, an isocyanate compound, etc. are mentioned, The compounding quantity is 1-40 parts with respect to 100 parts of polyamide-imide resins, Preferably it is 3-3. 20 parts. If the crosslinking agent is 1 part or less, no improvement in low-temperature adhesiveness or adhesive strength is observed, and if it is 40 parts or more, the heat resistance is lowered, which is not preferable.

  The heat-resistant adhesive of the present invention includes resins other than inorganic and organic pigments, dyes, antistatic agents, leveling agents, and polyamideimides, such as polyesters, polyamides, polyimides, and polyurethanes, as long as the content of the present invention is not impaired. It can mix | blend suitably.

As one method of using the heat-resistant adhesive of the present invention, a solution in which a crosslinking agent or an additive is blended with a polyamideimide resin solution is applied to an adherend, dried and then superimposed on the other adherend and heated. Examples of the method include pressure bonding with a roll or a heat press and, if necessary, heat curing treatment.
In this case, if the solvent remains in the adhesive layer, it may cause undesired results due to firing at the time of adhesion processing or a decrease in heat resistance itself. As shown in the production of the polyamideimide resin, it is preferable to use a polymer having a high-boiling point polymerization solvent replaced with a low-boiling point solvent such as alcohol, aromatic hydrocarbon, ether or ketone.

As another method of use, an adhesive film obtained by applying the heat-resistant adhesive composition solution of the present invention to a release substrate such as polypropylene film, polyester film, polyester film or paper treated with silicone or wax, and drying. And a sheet are sandwiched between two types of adherends, heated and pressed with a heating roll or a heat press, and cured if necessary.
Also in this case, as in the coating method, it is preferable to use a sheet dissolved in a low boiling point solvent in order to obtain a sheet having no residual solvent.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these examples.
In addition, the measured value in an Example is a value measured with the following method.
・ Glass transition temperature Adhesive solution was applied to a polypropylene film so that the dry film thickness was about 30 μm, and the film peeled off from the polypropylene film was dried at a frequency of 110 Hz using a dynamic viscoelasticity measuring device manufactured by the company. Measurement was performed and obtained from the inflection point of the storage elastic modulus.

Logarithmic viscosity A solution of 0.5 g of dried polymer in 100 ml of NMP was measured at 25 ° C. using an Ubbelohde viscosity tube.
-Adhesive strength A solution obtained by adding 10 parts of Epicoat 152 (epoxy compound manufactured by Japan Epoxy Co., Ltd.) to the polyamideimide resin solution to the polyamideimide resin solid content was applied to the electrolytic copper foil to a thickness of about 10 μm, at 130 ° C. After drying for 10 minutes, the coated surfaces are overlapped and pressed at 150 ° C, 20 kg / c for 30 seconds, pressed for 0 seconds, further heat treated at 150 ° C for 1 hour, and peeled off with Tensilon manufactured by Toyo Baldwin The strength was measured.

-Tensile modulus The same film as the glass transition temperature was measured using a Tensilon manufactured by Toyo Baldwin Co., Ltd., at a pulling speed of 200 mm / min.
-Solder resistance The state when the same sample whose adhesive strength was measured was floated in a solder bath at 290 ° C for 30 seconds was observed. The judgment was as follows.
○: No swelling or peeling.
X: Dandruff or peeling occurred.

6). Migration resistance A solution in which a circuit is formed on a copper-clad laminate Viroflex (manufactured by Toyobo Co., Ltd.) using 18 μm electrolytic copper foil so that the line / space is 70/70 μm, and 10 parts of Epicoat 152 is blended in the polyamideimide resin solution. Insulation resistance value after leaving in an atmosphere of 85 ° C. and 85% HR for 2 weeks with a voltage of 50 V applied between the terminals of the sample coated at 100 ° C. for 10 minutes and then heat treated at 130 ° C. for 30 minutes The change of was measured.
Judgment is as follows.
○: Insulation resistance value between lines is 1E + 08Ω or more ×: Insulation resistance value between lines is 1E + 08Ω or less

Example 1 (Production of polyamideimide resin A and adhesive a)
Dicarboxypoly (acrylonitrile-butadiene) with 0.7 mol of trimellitic anhydride (TMA), 0.25 mol of dimer acid, and molecular weight of 3500 (Ube Industries CTBN1300) in a four-necked flask equipped with a condenser and a nitrogen gas inlet × 13) 0.05 mol and 1.02 mol of diphenylmethane-4,4′-diisocyanate (MDI) were charged together with N, N′-dimethylacetamide (DMAc) to a solid content concentration of 40% while stirring. The temperature was raised to 120 ° C. for about 2 hours, and further heated to 150 ° C. for about 3 hours. While cooling this solution, toluene was added to adjust the solid content concentration to 30%. The obtained polyamideimide resin had a glass transition temperature of 164 ° C. and a logarithmic viscosity of 0.47 dl / g. This polymer solution was cast on a polypropylene film and dried at 100 ° C. for about 10 minutes to obtain a film having a thickness of 0.03 mm. The tensile elastic modulus of this film was 1050 MPa.
Next, 3 g of a phenol novolac type epoxy compound (Japan Epoxy Epicoat 152) was blended with 100 g of the obtained polyamideimide resin A solution to obtain an adhesive a.

Example 3 (Production of polyamideimide resin B and adhesive b)
In a four-necked flask equipped with a cooling tube and a nitrogen gas inlet, 0.83 mol of TMA, 0.1 mol of dimer acid, 0.07 mol of CTBN1300 × 13, and 1.02 mol of MDI were adjusted to a solid content concentration of 40%. The sample was charged with DMAc, heated to 120 ° C. with stirring, and reacted at 150 ° C. for about 3 hours. While this solution was cooled, toluene was added to adjust the solid content concentration to 30%. The obtained polyamideimide resin had a glass transition temperature of 178 ° C. and a logarithmic viscosity of 0.46 dl / g. The tensile modulus of the film produced by the same method as that for the polyamide-imide resin A was 960 MPa.
Next, the obtained polyamideimide resin B was used in the same manner as in Example 1 to obtain an adhesive b.

Example 6 (Production of polyamideimide resin C and adhesive c)
In a four-necked flask equipped with a condenser and a nitrogen gas inlet, 0.92 mol of TMA, 0.03 mol of polyester polyol having a molecular weight of 2000 (adipic acid / neopentyl glycol / hexanediol = 100/75/25 mol), CTBN 1300 × 13 was added to 0.05 mol and MDI, and 1.02 mol was added together with DMAc to a solid content of 40%. The temperature was raised to 120 ° C. with stirring for 2 hours, and further raised to 150 ° C. for about 2 hours. The reaction was allowed for 5 hours. The obtained polyamideimide resin had a glass transition temperature of 162 ° C. and a logarithmic viscosity of 0.38 dl / g. The tensile modulus of the film made from this polyamideimide resin solution was 1260 MPa.
Next, the obtained polyamideimide resin C was used in the same manner as in Example 1 to obtain an adhesive c.

Example 8 (Production of polyamideimide resin D and adhesive d)
In the method for producing polyamideimide resin A, 0.01 mol of potassium fluoride was added to a solution having a solid content concentration of 50% in which MDI was changed to isophorone diisocyanate (IPDI) and DMAc was changed to γ-butyrolactone. The mixture was reacted for 2 hours, further heated to 190 ° C. and reacted for about 3 hours. DMAc was added while cooling to a solid content concentration of 30%, and this solution was poured into ion-exchanged water to coagulate, thoroughly washed and then dried at 60 ° C. for 20 hours to obtain a solid resin. This solid resin was dissolved in tetrahydrofuran at room temperature so that the solid concentration was 30%. This polyamideimide resin D had a glass transition temperature of 155 ° C., a logarithmic viscosity of 0.48 dl / g, and a tensile elastic modulus of 990 MPa.
Next, the obtained polyamideimide resin D was used in the same manner as in Example 1 to obtain an adhesive d.

Example 10 (Production of polyamideimide resin E and adhesive e)
A polyamideimide resin E was produced under the same conditions as the polyamideimide resin C except that the polyester having a molecular weight of 2000 was changed to polycaprolactone having a molecular weight of 2000 (Placcel 220 manufactured by Daicel Corporation) in the production of the polyamideimide resin C. This polyamideimide resin E had a glass transition temperature of 147 ° C., a logarithmic viscosity of 0.47 dl / g, and a tensile modulus of elasticity of 1120 MPa.
Next, the obtained polyamideimide resin E was used in the same manner as in Example 1 to obtain an adhesive e.

Examples 4 and 11 (Production of adhesives b ′ and e ′)
3 g of trifunctional isocyanate compound coronate EH (manufactured by Nippon Polyurethane) was blended with 100 g of polyamideimide resins B and E to give adhesives b ′ and e ′, respectively.

Examples 2, 5, 7, 9, and 12 (sheet formation)
Adhesives a, b, c, d, and e are respectively applied to a 50 μm polypropylene film, dried at 60 ° C. for 5 minutes and 130 ° C. for 10 minutes, and then peeled off to form an adhesive sheet a ″, b having a thickness of 20 μm. '', C '', d '', e '' were obtained.

Example 13 (Example of manufacturing a flexible copper-clad laminate)
Adhesives a, b, c, d, e, b 'and e' were each applied to a 1/2 oz electrolytic copper foil with a gap of 100 μm, dried at 60 ° C for 5 minutes and 130 ° C for 10 minutes, and then polyimide on the adhesive surface. The films were overlapped and bonded with a roll laminator at 180 ° C., and then left in a nitrogen gas oven at 220 ° C. for 10 hours in a state of being wound on a roll to obtain a flexible copper-clad laminate.

Reference Example 1 (Lamination Example 1)
Reinforcement made of 0.3mm aluminum plate via adhesive sheets a ", b", c ", d", e "on the polyimide film surface of the copper-clad laminate made using adhesive b The plates were overlapped and pressure-bonded at a pressure of 20 kgf / cm 2 for 20 minutes using a 170 ° C. heat press. Thereafter, heat treatment was performed for 1 hour under pressure at the same temperature.

Reference Example 2 (Lamination Example 2)
Using Toyobo copper-clad laminate Viroflex, apply adhesives a, b, c, d, e to a circuit board for migration test with a line / space of 70 μm / 70 μm to be about 20 μm, 5 at 60 ° C. And then dried at 130 ° C. for 10 minutes and further heated and cured at 150 ° C. for 1 hour. A voltage of 10 V was applied between the electrodes in an environment of 80 ° C. and 85% RH, and the insulating properties after being left for 100 hours were evaluated.

Comparative Examples 1 and 2 (Production of polyamideimide resin F, adhesive f and adhesive sheet f ″)
The glass transition temperature obtained in Example 1 was 98.degree. C. all obtained under the same conditions as in Example 1 except that the raw materials were charged at TMA 0.875 mol, CTBN 1300.times.13 at 0.125 mol, and MDI 1.02 mol. An adhesive f manufactured by blending 3 g of Epicoat 152 with 100 g of a 30% DMAC solution of polyamideimide resin having a logarithmic viscosity of 0.55 dl / g and a tensile modulus of 555 MPa when formed into a film, and a sheet f ″ thereof In the same manner as in Reference Examples 1 and 2, a copper-clad laminate was produced and a reinforcing plate was bonded.

Comparative Examples 3 and 4 (Production of polyamideimide resin G, adhesive g, and adhesive sheet g ″)
Γ-BL was added to a 4-tack flask equipped with a cooling pipe and a nitrogen gas inlet with 0.25 mol of TMA, 0.75 mol of ethylene glycol ditrimellitate and 1 mol of diphenylmethane 4,4 ′ diisocyanate so that the solid content concentration would be 50%. Then, the mixture was reacted at 150 ° C. for 2 hours and at 200 ° C. for 5 hours. After cooling, it was diluted with cyclohexanone so that the solid content concentration was 25%. The obtained polyamideimide resin G had a glass transition temperature of 216 ° C. and a logarithmic viscosity of 0.45 dl / g. This resin solution was cast on a polyester film, dried at 100 ° C., peeled from the polyester film, fixed to a metal frame and dried at 200 ° C. for 20 hours, and the tensile modulus of the film was 2640 MPa. .
Production of a copper-clad laminate and laminating a reinforcing plate in the same manner as in Reference Examples 1 and 2 using an adhesive composition g in which 3 g of Epicoat 152 was blended with 100 g of this 30% solution of polyamideimide resin G and its sheet g ″ Went.

Comparative Examples 5 and 6 (Production of polyamideimide resin H and adhesive h)
Polyamideimide resin H was produced in the same manner as in Example 1 except that the amount of MDI charged in Example 1 was 0.9 mol. The logarithmic viscosity of the obtained resin was 0.08 dl / g. Since this resin has a low molecular weight and does not form a film, the glass transition temperature and tensile elastic modulus could not be measured. A copper-clad laminate was produced using an adhesive h in which 3 parts of Epicoat 152 was blended with 100 parts of a 30% solution of this resin (expected to be close to the same polyamideimide resin B in composition).

The results of the above examples are summarized in Table 1.

  As is apparent from the results of the examples, according to the present invention, the adhesiveness to metal and polyimide films, the solder resistance, and the anti-migration property under high temperature and high humidity are particularly useful for circuit boards. An adhesive, an adhesive sheet, and a printed circuit board using these can be provided.

Claims (5)

A modified polyamideimide resin in which poly (acrylonitrile-butadiene) and dimer acid or polyester are copolymerized with polyamideimide, wherein the modified polyamideimide resin has a glass transition temperature of 120 ° C. or higher and a logarithmic viscosity of 0.1 dl. / G or more, and a tensile elasticity modulus is 1500 Mpa or less, The modified polyamide imide resin characterized by the above-mentioned. The modified polyamideimide resin according to claim 1, wherein the modified polyamideimide resin is dissolved in one or more mixed solvents of ethanol, toluene, tetrahydrofuran, cyclohexanone, and cyclopentanone. A heat-resistant adhesive in which the modified polyamideimide resin according to claim 1 or 2 is blended with one or more of a polyfunctional epoxy compound, a melamine compound, and an isocyanate compound as a crosslinking agent. An adhesive sheet formed from the heat-resistant adhesive according to claim 3. A printed circuit board using the heat-resistant adhesive according to claim 3 or 4 or a sheet thereof.