Fluxing underfill compositions

1. A thermosetting resin composition, comprising:

An epoxy component;

A hardener;

A filler component; and

A solid organic acid, having a melting point in the range of 130° C. to 245° C., wherein the solid organic acid is embraced by the following structure:

wherein R is hydrogen or C 1-4 alkyl; R 1 is hydrogen, aryl or phenolic; R 2 is hydrogen, hydroxyl, C 1-4 alkyl or O—Ra, wherein Ra is C(═O)—Rb wherein Rb is C 1-4 alkyl; R 3 , R 4 and R 5 are each independently selected from hydrogen, C 1-4 alkyl or O—Rb, wherein Rb is C 1-4 alkyl; R 6 is hydrogen, hydroxyl, or O—Rb, wherein Rb is C 1-4 alkyl; and R 7 -R 9 are each independently selected from hydrogen, or C 1-4 alkyl.

2. The composition of claim 1 , wherein the solid organic acid has a melting point in the range of 140° C. to 230° C.

3. The composition of claim 1 , wherein the solid organic acid has a melting point in the range of 165° C. to 175° C.

4. The composition of claim 1 , wherein the solid organic acid is embraced by one or more of 2,3-dihydroxy benzoic acid, syringic acid, 3,4,5-trimethoxy benzoic acid, orselliaic acid, diphenolic acid and acetylsalicylic acid.

5. The composition of claim 1 , wherein the composition cures at a temperature above about 130° C.

6. The composition of claim 1 , wherein the composition cures at a temperature above about 260° C.

7. The composition of claim 1 , in the form of a film.

8. The composition of claim 7 , in the form of a film disposed on a release liner.

9. The composition of claim 7 , in the form of a film disposed on one or more of a semiconductor chip, a carrier substrate, or a circuit board.

10. The composition of claim 1 , cured under thermal compression bonding conditions.

11. An assembly comprising:

A thermosetting resin composition, comprising:

An epoxy component;

A hardener;

A filler component; and

A solid organic acid, having a melting point in the range of 130° C. to 245° C., wherein the solid organic acid is embraced by the following structure:

wherein R is hydrogen or C 1-4 alkyl; R 1 is hydrogen, aryl or phenolic; R 2 is hydrogen, hydroxyl, C 1-4 alkyl or O—Ra, wherein Ra is C(═O)—Rb wherein Rb is C1-4 alkyl; R 3 , R 4 and R 5 are each independently selected from hydrogen, C 1-4 alkyl or O—Rb, wherein Rb is C 1-4 alkyl; R 6 is hydrogen, hydroxyl, or O—Rb, wherein Rb is C 1-4 alkyl; and R 7 -R 9 are each independently selected from hydrogen, or C 1-4 alkyl, and wherein the composition is in film form and disposed between:

A silicon wafer having an active side with solder bumps protruding therefrom and

A semiconductor die with solder balls attached thereto and in alignment with the solder bumps on the silicon wafer.

12. The assembly of claim 11 , wherein the solid organic acid acts as a fluxing agent for the solder balls.

13. The assembly of claim 11 , wherein the solid organic acid acts as a catalyst for cure of the epoxy component.

14. The assembly of claim 11 , wherein the solder balls are constructed from Sn-Pb solder alloys, Pb-free solder alloys, and combinations thereof.

15. The assembly of claim 14 , wherein the composition comes into contact with the solder balls at reflow temperatures the composition wets the solder balls to form a contact angle of less than 90°.

16. The assembly of claim 11 , wherein the solder ball is constructed from a member selected from the group consisting of Sn63:Pb37, Pb95:Sn5, Sn:Ag3.5:Cu0.5 and Sn:Ag3.3:Cu0.7.

17. A method of making a semiconductor device, steps of which comprise:

providing a silicon wafer;

providing an underfill composition according to claim 1 onto a surface of the silicon wafer to form a layer thereof;

placing solder balls at predetermined positions on the underfill layer;

providing a substrate having electrical contact pads on a surface thereof;

mating the silicon wafer with the substrate such the solder balls are aligned with the electrical contact pads to form a pre-assembly;

exposing the pre-assembly to elevated temperature conditions sufficient to provide fluxing following by curing of the underfill composition to form an assembly; and

singulating the assembly to form a plurality of semiconductor devices.

18. A semiconductor device comprising:

At least one semiconductor chip having solder balls attached thereto;

At least one carrier substrate or a circuit board having electrical contact pads on a surface thereof to which the at least one semiconductor chip is electrically interconnected through the solder balls; and

A composition according to claim 1 disposed between the semiconductor chip and the carrier substrate or circuit board.