Thermoplastic film die attach adhesives
AssigneeNational Starch and Chemical Investment Holding Corporation
InventorRobert Edelman
Life of this patent
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Abstract
This is a thermally conductive adhesive having excellent die shear strength, in film form, and having a weight average molecular weight of about 100,000 to 150,000, prepared from a mixture of a dietherdianhydride, a meta-substituted benzenediamine, a polysiloanediamine, and a thermally conductive filler, that is suitable as a die attach adhesive: it bonds rapidly without the need for curing or baking off-line; does not produce excess stress on the die; requires no refrigeration; provides uniform bond line thickness between the die and paddle; can be used at temperatures that do not oxidize copper lead frames or produce excessive thermal stress; can be reworked; and can exert adequate adhesion during the processes of wire bonding and molding.
Claims16
A thermally conducting, thermoplastic melt die-attach adhesive film, which softens at 200.degree. C. but is firm at 175.degree. C. to maintain adhesion, comprising:
- (A) a normally solid thermoplastic polyimide polymeric binder having a weight average molecular weight of about 100,000 to 150,000 and synthesized from:
- (1) an aromatic dietherdianhydride having the structure:
- ##STR14## in which K is a substituted or unsubstituted group of the formula:
- ##STR15## in which W is --O--, --S--, --SO.sub.2, linear or branched alkylene or alkenylene having 1 to 8 carbon atoms or --(R)C(L)--, in which R and L can be the same or different lower alkyls having 1 to 8 carbons or aryl groups having 6 to 24 carbon atoms, and m is 0 or 1;
- and
- (2 ) a meta-substituted benzenediamine having the structure:
- ##STR16## in which Y is a divalent unsubstituted meat-phenylene radical or a meta-phenylene radical substituted with at least one lower alkyl group containing 1 to 8 carbon atoms;
- T is selected from the group consisting of --O--, --S--, --SO--, --SO.sub.2, --CO-- and lower alkylene having 1 to about 6 carbon atoms;
- the benzenediamine present in an amount of about 20 to about 50 mole percent of the total diamine content of the polyimide polymeric binder;
- and
- (3) a polysiloxanediamine having the structure:
- ##STR17## in which Q is a meta-substituted arylene;
- Z is a divalent oxygen, sulfide, sulfone, sulfoxide or carboxylic ester or amide group;
- D is a hydrocarbylene group;
- R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 are the same or different alkyls having 1 to 8 carbons;
- and x, y and z are integers having values of 0 to 100;
- the polysiloxane diamine present in an amount of about 80 to about 50 mole percent of the total diamine content of the polyimide polymeric binder;
- the dianhydride content and total diamine content present in an unequal molar ratio of diamine to dianhydride of 0.95-0.97:1;
- and
- (4) p-aminophenol present as an end-capping agent in an amount up to about 15% of the theoretical equivalents of excess anhydride functionality;
- and
- (B) thermally conductive material present in an effective amount up to 85% by weight of the die-attach adhesive film to provide a conducting medium.
A thermally conducting, thermoplastic melt adhesive film comprising:
- (A) a normally solid thermoplastic polyimide polymeric binder having a weight average molecular weight of about 100,000 to 150,000, and synthesized from:
- (1) an aromatic dietherdianhydride having the structure:
- ##STR18## in which K is a substituted or unsubstituted group of the formula:
- ##STR19## in which W is --O--, --S--, --SO.sub.2, linear or branched alkylene or alkenylene having 1to 8 carbon atoms or --(R)C(L)--, in which R and L can be the same or different lower alkyls having 1 to 8 carbons or aryl groups having 6 to 24 carbon atoms, and m is 0 or 1;
- and
- (2) a meta-substituted benzenediamine having the structure:
- ##STR20## in which Y is a divalent unsubstituted meta-phenylene radical or a meta-phenylene radical substituted with at least one lower alkyl group containing 1 to about 8 carbon atoms;
- T is selected from the group consisting of --O--, --S--, --SO--, --SO.sub.2, --CO-- and lower alkylene having 1 to about 6 carbon atoms;
- the benzenediamine present in an amount of about 20 to about 50 mole percent of the total diamine content of the polyimide polymeric binder;
- and
- (3) a polysiloxanediamine having the structure:
- ##STR21## in which Q is arylene;
- Z is a divalent oxygen, sulfide, sulfone, sulfoxide or carboxylic ester or amide group;
- D is a hydrocarbylene group;
- R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 are the same or different alkyls having 1 to 8 carbons;
- and x, y and z are integers having values of 0 to 100;
- the polysiloxane diamine present in an amount of about 80 to about 50 mole percent of the total diamine content of the polyimide polymeric binder;
- the dianhydride content and total diamine content present in an unequal molar ratio of diamine to dianhydride of 1.03-1.05:1;
- and
- (4) phthalic anhydride present as an end-capping agent in an amount up to about 15% of the theoretical equivalents of excess amine functionality;
- and
- (B) thermally conductive material present in an effective amount to provide a conducting medium.
Dependencies are inferred from the claim text.