High purity epoxy formulations for use as die attach adhesives

• US 4,975,221 A
• Filed: 05/12/1989
• Issued: 12/04/1990
• Est. Priority Date: 05/12/1989
• Status: Expired due to Term

• Current Assignee: National Starch and Chemical Investment Holding Corporation
• Original Assignee: National Starch and Chemical Investment Holding Corporation
• Inventors: Park, Song, Chen, Shuhchung S., Schoenberg, Jules E.
• Primary Examiner(s): Barr, Josephine
• Application Number:
  US07/350,987
• Time in Patent Office: 571 Days
• Field of Search: 252/518, 252/520, 252/512, 252/513, 252/514, 252/521, 252/62, 252/3 T, 523/457-459, 523/427, 523/428, 523/433, 523/466, 525/42, 525/43, 525/407, 525/423, 428/413, 428/418, 428/901, 156/330, 437/1, 357/8
• US Class Current: 252/512
• CPC Class Codes: C08L 2666/22 Macromolecular compounds not provided for in C08L2666/16 - C08L2666/20
• CPC Class Codes: C09J 163/00 Adhesives based on epoxy resins; Adhesives based on derivatives of epoxy resins
• CPC Class Codes: H01L 24/29 of an individual layer connector
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/10253 Silicon [Si]
• CPC Class Codes: H01L 2924/15747 Copper [Cu] as principal constituent
• CPC Class Codes: Y10T 428/31511 Of epoxy ether
• CPC Class Codes: Y10T 428/31529 Next to metal

Abstract

This invention presents improved epoxy-based die attach adhesives which are of low viscosity, high ionic purity, and stable toward thermal cycling. This improvement is obtained by including in the formulation carboxy terminated polymers which are the reaction products of polyether diols with cyclic dianhydrides.

Claims

1. In an epoxy-based die-attach adhesive composition, wherein the adhesive comprises one or more curable epoxy compounds, a conductive filler, and suitable curing agents the improvement comprising adding to said adhesive 2-50 PHR (by wt.) of an epoxy modifier which comprises a carboxy-terminated polymer of the general formula:

##STR6## wherein R'"'"' is a C₂ -C₂₀ straight or branched chain or cyclic saturated or unsaturated hydrocarbon,

R is a linear hydrocarbon having ether linkages or linear hydrocarbons substituted with sulfone, sulfide, phosphonate, phosphine oxide, silane, or siloxane, preferably a linear hydrocarbon having ether linkages,

X is O, NH, or NR",

R" is C₁ -C₁₀ alkyl, alkenyl, or aryl, and

n is at least 1,

such that the die attach adhesive is of low viscosity and stable toward thermal cycling.

2. The epoxy-based die attach adhesive of claim 1, wherein the carboxy terminated polymer added to the adhesive is about 2-50 parts per hundred parts epoxy by wt.

3. The epoxy-based die attach adhesive of claim 1, wherein the epoxy compound is selected from the group consisting of diglycidyl ethers of polyhydric phenols, trisepoxides, aliphatic diepoxides, and cycloaliphatic diepoxides.

4. The epoxy-based die attach adhesive of claim 1, wherein the carboxy terminated polymer is admixed with the epoxy.

5. The epoxy-based die attach adhesive of claim 1, wherein the carboxy terminated polymer is prereacted with the epoxy.

6. The epoxy-based die attach adhesive of claim 1, wherein the carboxy terminated polymer is the formula ##STR7## wherein R'"'"' is a C₂ -C₂₀ straight or branched chain or cyclic saturated or unsaturated aliphatic or aromatic hydrocarbon,

R is a linear polyether,

X is O.

7. The epoxy-based die attach adhesive of claim 6 ,wherein the linear polyether has a molecular weight of about 500 to about 5000.

8. The epoxy-based die attach adhesive of claim 6 wherein R is ##STR8## wherein n is at least 8.

9. The epoxy-based die-attach adhesive of claim 6 wherein R is ##STR9## wherein n is at least 6.

10. The epoxy-based die attach adhesive of claim 1, which comprises 100-125 parts (by wt) of one or more epoxy compounds, 3-50 parts (by wt) of carboxy terminated polymer modifier, 0-20 parts (by wt) curing agent, 2.5-10 parts (by wt) catalyst, 0-2 parts (by wt) adhesion promoter, and 300-600 parts (by wt) conductive filler.

11. The epoxy-based die attach adhesive of claim 1, wherein the conductive filler is a thermally conductive filler selected from the group consisting of magnesium oxide, calcium barbonate, silicon dioxide, titanium dioxide, and alumina.

12. The epoxy-based die attach adhesive of claim 1, wherein the conductive filler is an electrically conductive filler selected from the group consisting of powdered or flaked, or a mixture of powdered and flaked metal.

13. The epoxy-based die attach adhesive of claim 12 wherein the curing agent is selected from the group consisting of phenol novalacs, aromatic amines, aromatic diamines, and dicyandiamides.

14. The epoxy-based die attach adhesive of claim 8, wherein the catalyst is selected from the group consisting of substituted ureas, substituted imidazoles, and tertiary amines.

15. The epoxy-based die attach adhesive of claim 14, wherein the catalyst is dimethylbenzylamine.

16. The epoxy-based die attach adhesive of claim 12, wherein the metal is selected from the group consisting of silver, gold, copper, and nickel.

17. A semiconductor device mounted on a substrate with the adhesive of claim 1.