ADHESIVE COMPOSITION USING POLYAMIDE-IMIDE RESIN

Abstract

The present invention provides an adhesive composition for a flexible printed wiring board containing (A) an epoxy resin; (B) no phosphorus-containing epoxy resin; and (C) a polyamide-imide resin.

Claims

1. An adhesive composition wherein a polyamide-imide resin and an epoxy resin are compounded, characterized in that said adhesive composition has characteristics of the following (A) to (C): (A) 15 parts by mass to 40 parts by mass of the epoxy resin is compounded to 85 parts by mass to 60 parts by mass of the polyamide-imide resin; (B) No phosphorus-containing epoxy resin is used as the epoxy resin or, even if used, a compounding amount of the phosphorus-containing epoxy resin to 100 parts by mass of the polyamide-imide resin is less than 1 part by mass; and (C) The polyamide-imide resin is a polyamide-imide resin comprising a constituent unit derived from acid ingredients of the following (a) to (c) and a constituent unit derived from a diisocyanate ingredient having an aromatic ring or derived from a diamine ingredient having an aromatic ring and, when the constituent units derived from total acid ingredients in the polyamide-imide resin are taken as 100 mol %, a rate of each constituent unit derived from each acid ingredient is 1 to 6 mol % for (a), 10 to 80 mol % for (b) and 10 to 89 mol % for (c): (a) acrylonitrile-butadiene rubber which has carboxyl groups in both terminals, has weight-average molecular weight of 500 to 5,000, and has a rate of an acrylonitrile moiety of 10 to 50% by mass; (b) aliphatic dicarboxylic acid which has a carbon number of 4 to 12; and (c) anhydride of polycarboxylic acid which has an aromatic ring.

2. The adhesive composition according to claim 1, wherein a phosphorus-type flame retardant is further compounded therewith and a content of phosphorus in a nonvolatile ingredient in the adhesive composition is 1.0 to 5.0% by mass.

3. The adhesive composition according to claim 2, wherein a phosphorus-type flame retardant having no functional group which is reactive with epoxy and a phosphorus-type flame retardant having two or more functional groups which are reactive with epoxy are jointly used as the phosphorus-type flame retardant.

4. The adhesive composition according to claim 1, wherein a total amount of chlorine of the epoxy resin is 500 ppm or less in the nonvolatile ingredient of the adhesive composition.

5. The adhesive composition according to claim 1, wherein a resin having glass transition temperature of 200 C. or higher is further compounded therewith.

6. A coverlay film which is comprising an adhesive layer made from the adhesive composition mentioned claim 1.

7. The coverlay film according to claim 6, wherein an amount of residual solvent in the coverlay film in a state of B stage is less than 1.5% by mass.

8. An adhesive film which is comprising an adhesive layer made from the adhesive composition mentioned in claim 1.

9. The adhesive film according to claim 8, wherein an amount of residual solvent in the adhesive film in a state of B stage is less than 1.5% by mass.

10. A three-layered copper-lined layered plate which is comprising an adhesive layer made from the adhesive composition mentioned in claim 1.

11. A flexible printed wiring board which comprises the adhesive composition mentioned in claim 1.

12. A flexible printed wiring board which comprises the coverlay film mentioned in claim 6.

13. A flexible printed wiring board which comprises the adhesive film mentioned in claim 8.

14. A flexible printed wiring board which comprises the three-layered copper-lined layered plate mentioned in claim 10.

Description

EXAMPLES

[0080] As hereunder, effects of the present invention will be demonstrated by way of Examples although the present invention is not limited to those Examples only. Evaluations of the characteristics in Examples were carried out according to the following methods.

[0081] Adhesive Property

[0082] A solution of the adhesive composition was applied to a polyimide film (Apical 12.5 NPI manufactured by Kaneka) so as to make the thickness thereof after drying 20 m and then dried at 140 C. for 3 minutes using a hot-air drier to give a sample in the state of B stage. Aside of this B stage sample to which the adhesive agent was applied and a glossy side of a copper foil (BHY manufactured by JX Nikko Nisseki; thickness: 18 RI) were subjected to a thermal compression treatment using a vacuum press laminating machine in vacuo at 160 C. and 3 MPa for 30 seconds. After that, a thermal curing treatment was carried out at 150 C. for 4 hours. From the sample after the curing, the polyimide film was peeled off using a tensile tester (Autograph AG-X plus manufactured by Shimadzu) under an environment of 25 C. in a direction of 90 at a rate of 50 mm/minute whereupon adhesive strength was measured.

[0083] When the sample exhibited adhesive strength of 0.5 N/mm or more, it was evaluated as . When the sample exhibited adhesive strength of less than 0.5 N/mm, it was evaluated as x.

[0084] Flame Retarding Property

[0085] A sample in B stage was prepared in the same manner as in the case for the evaluation of adhesive property. Then, a side to which the adhesive was applied and a polyimide film (Apical 12.5 NPI manufactured by Kaneka) were subjected to a thermal compression treatment using a vacuum press laminating machine in vacuo at 160 C. and 3 MPa for 30 seconds. After that, a thermal curing treatment was carried out at 150 C. for 4 hours. The sample after the curing was subjected to evaluation for flame retarding property in accordance with UL-94VTM standard.

[0086] When the sample satisfied VTM-0, it was evaluated as . When the sample did not satisfy VTM-0, was evaluated as x.

[0087] Embrittlement in B Stage

[0088] A solution of the adhesive composition was applied to a PET film (E 5101 manufactured by Toyobo; thickness: 50 m) so as to make the thickness thereof after drying 20 m and then dried at 140 C. for 3 minutes to give a sample in a state of B stage.

[0089] The sample was bent and when the adhesive layer was cracked immediately after application/drying of the adhesive, it was evaluated as x. When the adhesive layer was cracked after one week at room temperature, it was evaluated as A. When the adhesive layer was not cracked even after one week at room temperature, it was evaluated as .

[0090] Reliability for Insulating Property

[0091] A sample in B stage was prepared in the same manner as in the case for the evaluation of adhesive property. Then, it was subjected to a thermal compression treatment using a vacuum press laminating machine at 160 C. and 3 MPa for 30 seconds in vacuo, in a comb pattern with L/S=50/50 m. After that, a thermal curing treatment was carried out at 150 C. for 4 hours. Voltage of 200 V was applied thereto for 250 hours under the environment wherein the temperature was 85 C. and the humidity was 85%.

[0092] When the resistance after 250 hours was 110.sup.9 or more and no dendrite was found, it was evaluated as oo. When the resistance after 250 hours was 110.sup.8 or more and less than 110.sup.9 or more and no dendrite was found, it was evaluated as . When the resistance after 250 hours was less than 110.sup.8 or dendrite was generated, it was evaluated as x.

[0093] Heat Resistance to Solder

[0094] A sample was prepared in the same manner as in the case for the evaluation of adhesive property. Then, it was cut into 20-mm squares and floated on a solder bath of 300 C. in such a state that the polyimide surface was made upside.

[0095] When neither swelling nor detachment was found, it was marked as . When either swelling or detachment was found, it was marked as x.

[0096] Polymerization of Polyamide-Imide Resins 1 to 9

[0097] Polymerization of the polyamide-imide resin was carried out using the starting material resin composition (mol %) as shown in Table 1. To be more specific, polymerization was carried out as follows in the case of the polyamide-imide resin 1.

[0098] Trimellitic anhydride (105.67 g, 0.55 mol), 80.90 g (0.40 mol) of sebacic acid, 175 g (0.05 mol) of acrylonitrile butadiene rubber having carboxyl groups in both terminals, 250.25 g (1.00 mol) of 4,4-diphenylmethane diisocyanate and 785.7 g of dimethylacetamide were added to a four-necked separable flask equipped with a stirrer, a cooling pipe, a nitrogen-introducing pipe and a thermometer so as to make the concentration of the resin after decarbonization 40% by weight. Then, the mixture was made to react for 2 hours by raising the temperature up to 100 C. under nitrogen atmosphere and further heated up to 150 C. and the reaction was carried out for 5 hours. After that, 436.5 g of dimethylacetamide was added thereto for dilution so as to make the concentration of the resin 30% by weight whereupon a solution of the polyamide-imide resin 1 was prepared. With regard to other polyamide-imide resins 2 to 9, polymerization of the resin was carried out using the starting material resin compositions as shown in Table 1 to give the solutions.

[0099] Polymerization of highly heat-resisting resin (polyamide-imide resin 10)

[0100] As a highly heat-resisting resin, the polyamide-imide resin 10 solely consisting of a material having an aromatic ring (trimellitic anhydride) was polymerized in the same manner as in the above case for the polyamide-imide resin 1. A solution of the resulting polyamide-imide resin 10 was applied onto a copper foil so as to make the thickness thereof after drying 15 m, dried at 100 C. for 5 minutes and further subjected to drying using hot air at 250 C. for 1 hour. After that, the sample was dipped into a solution of ferric chloride to remove the copper foil whereupon a film of the polyamide-imide 10 was prepared. Dynamic viscoelasticity of the product was measured using DVA-220 (a dynamic viscoelasticity measuring device manufactured by IT Keisoku Seigyosha) under the frequency of 110 Hz and the temperature-rising rate of 4 C./minute. The glass transition temperature of the resulting polyamide-imide 10 was calculated from the inflection point of the storage elastic modulus thereof and found to be 280 C.

[0101] Preparation of Solutions of Adhesive Compositions

[0102] Solutions of the adhesive compositions of Examples 1 to and Comparative Examples 1 to 7 dissolved in dimethylacetamide were prepared according to the adhesive compounding rate (in % by mass of solid) as shown in Table 2 and the above properties were evaluated.

TABLE-US-00001 TABLE 1 highly poly- poly- poly- poly- poly- poly- poly- poly- poly- heat-resisting amide- amide- amide- amide- amide- amide- amide- amide- amide- resin imide imide imide imide imide imide imide imide imide (polyamide-imide material resin 1 resin 2 resin 3 resin 4 resin 5 resin 6 resin 7 resin 8 resin 9 resin 10) resin NBR 2.5 1.5 2 2.5 5 2.5 2.5 0.5 10 composition sebacic acid 40 40 35 50 40 40 40 40 (mol %) decanoic diacid 40 TMA 57.5 58.5 63 47.5 55 57.5 59.5 50 100 H-TMA 57.5 MDI 100 100 100 100 100 100 100 100 100 100 NBR: modified acrylonitrile-butadiene rubber having carboxyl groups in both terminals TMA: trimellitic anhydride H-TMA: cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride MDI: diphenylmethane-4,4-diisocyanate

TABLE-US-00002 TABLE 2 Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- ple 1 ple 2 ple 3 ple 4 ple 5 ple 6 ple 7 ple 8 ple 9 ple 10 ple 11 adhesive polyamide-imide resin 1 60 50 60 60 65 40 compounding rate polyamide-imide resin 2 60 [in % by mass polyamide-imide resin 3 60 of solid] polyamide-imide resin 4 60 polyamide-imide resin 5 60 polyamide-imide resin 6 60 polyamide-imide resin 7 polyamide-imide resin 8 polyamide-imide resin 9 polyamide-imide resin 10 20 epoxy resin jER 152 16 16 16 16 16 16 26 16 16 23 16 EXA-9726 phosphorus- BCA 18 18 18 18 18 18 18 12 6 7 18 type flame HCA retardant SPH-100 6 6 6 6 6 6 6 12 18 5 6 content of phosphorus 2.6 2.6 2.6 2.6 2.6 2.6 2.6 2.7 2.9 1.3 2.6 adhesive adhesive property characteristics flame retarding property embrittlement in B stage reliability for the insulating property heat resistance to solder Comparative Comparative Comparative Comparative Comparative Comparative Comparative Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 adhesive polyamide-imide resin 1 70 40 60 60 compounding rate polyamide-imide resin 2 [in % by mass polyamide-imide resin 3 of solid] polyamide-imide resin 4 polyamide-imide resin 5 polyamide-imide resin 6 polyamide-imide resin 7 60 polyamide-imide resin 8 60 polyamide-imide resin 9 60 polyamide-imide resin 10 epoxy resin jER 152 16 16 16 6 36 10 EXA-9726 16 6 phosphorus- BCA 18 18 18 18 18 18 18 type flame HCA retardant SPH-100 6 6 6 6 6 6 6 content of phosphorus 2.6 2.6 2.6 2.6 2.6 3.0 2.7 adhesive adhesive property x characteristics flame retarding property embrittlement in B stage x reliability for the x x x insulation property heat resistance to solder x x jER 152: manufactured by Mitsubishi Chemical; epoxy resin (containing no phosphorus) EXA-9726: manufactured by DIC; phosphorus-containing epoxy resin BCA: manufactured by Sanko; phosphorus-type flame retardant having no functional group which is reactive with epoxy HCA: manufactured by Sanko; phosphorus-type flame retardant having one functional group which is reactive with epoxy SPH-100: manufactured by Otsuka Chemical; phosphorus-type flame retardant having three functional groups which are reactive with epoxy

[0103] As will be noted from Table 2, the adhesive compositions of Examples 1 to 11 satisfying the conditions of the present invention showed excellent results in terms of adhesive property, flame retarding property, embrittlement in B stage, reliability for insulating property and heat resistance to solder. On the contrary, in Comparative Examples 1 to 3 using polyamide-imide resins which do not satisfy the conditions of the present invention, in Comparative Examples 4 and 5 wherein the compounding rate of polyamide-imide resin to epoxy resin is out of the scope of the present invention and in Comparative Examples 6 and 7 using more than the predetermined amount of phosphorus-containing epoxy resin, the result for any of the properties was not satisfactory.

INDUSTRIAL APPLICABILITY

[0104] The adhesive composition of the present invention is excellent in terms of insulating property, flexibility, flame retarding property and fluidity. Accordingly, the adhesive composition of the present invention is suitable for a coverlay film, an adhesive film, a three-layered copper-line laminated plate, etc. whereby it is quite useful.