Composition for photoimaging

• US 6,210,862 B1
• Filed: 09/10/1998
• Issued: 04/03/2001
• Est. Priority Date: 03/03/1989
• Status: Expired due to Term

• Current Assignee: GlobalFoundries, Inc.
• Original Assignee: International Business Machines Corporation
• Inventors: Day, Richard Allen, Russell, David John, Glatzel, Donald Herman
• Primary Examiner(s): Hamilton, Cynthia
• Application Number:
  US09/150,824
• Time in Patent Office: 936 Days
• Field of Search: 430/280.1, 522/31, 522/146, 522/109
• US Class Current: 430/280.1
• CPC Class Codes: C08G 59/38 together with di-epoxy compounds
• CPC Class Codes: C08G 59/687 containing sulfur
• CPC Class Codes: G03F 7/038 Macromolecular compounds which are rendered insoluble or differentially wettable G03F7/075 takes precedence; macromolecular azides G03F7/012; macromolecular diazonium compounds G03F7/021
• CPC Class Codes: G03F 7/0385 using epoxidised novolak resin
• CPC Class Codes: H05K 3/287 Photosensitive compositions
• CPC Class Codes: Y10S 428/901 Printed circuit

Abstract

According to the present invention, an improved photoimagable cationically polymerizable epoxy based solder mask is provided that contains a non-brominated epoxy resin system and from about 0.1 to about 15 parts, by weight per 100 parts of resin system, of a cationic photoinitiator. The non-brominated epoxy-resin system has solids that are comprised of from about 10% to about 80% by weight, of a polyol resin having epoxy functionality; from about 0% to about 90% by weight of a polyepoxy resin; and from about 25% to about 85% by weight of an difunctional epoxy resin. Since the photosensitive cationically polymerizable epoxy based solder mask does not contain bromine, it is particularly advantageous halogens in waste processing chemicals or in incinerated scrap circuit boards are regulated by environmental concerns. The photosensitive cationically polymerizable non-brominated epoxy based solder mask has a glass transition temperature greater than about 100° C., preferably greater than about 110° C. The solder mask dries to a tack-free film; thus, artwork used in the photoimaging process will not stick to the dried soldermask film. The polyol resin which is a condensation product of epichlorohydrin and bisphenol A, has a weight average molecular weight of between about 40,000 and 130,000. The polyepoxy resin is an epoxidized multi-functional bisphenol A formaldehyde novolak resin having a weight average molecular weight of 4,000 to 10,000. The epoxidized diglycidyl ether of bisphenol A has two epoxide groups per molecule, a melting point of between about 80° C. and about 110° C. and a weight average molecular weight of between about 600 and 2,500. The invention also relates to a cationically polymerized solder mask.

Claims

1. An improved, non-brominated photosensitive cationically polymerizable epoxy composition for use as soldermask comprising;

a. a non-brominated epoxy resin system comprising;

i. from about 10% and about 80% by weight of a polyol resin which is a condensation product of epichlorohydrin and bisphenol A, having a molecular weight of between about 40,000 and about 130,000 and a weight per epoxide of from about 20,000 to about 65,000;

ii. between about 0% and about 90% by weight of an epoxidized multifunctional bisphenol A formaldehyde novolak resin having a molecular weight of between about 4,000 and about 10,000 and a weight per epoxide of about 180 to 500;

iii. between about 25% and about 85% by weight of a solid epoxidized glycidyl ether of bisphenol A having a softening point of between about 60°

C. and about 110°

C. and a molecular weight of between about 600 and about 2,500 and a weight per epoxide of about 300 to 1250; and

,

b. from about 0.1 to about 15 parts by weight per 100 parts resin system of a cationic photoinitiator capable of initiating polymerization in said epoxy resin system upon exposure to actinic radiation.

2. The epoxy composition as defined in claim 1 wherein there is between about 20 and about 40 percent of the polyol resin, between about 20% and about 35% of the epoxidized multifunctional bisphenol A formaldehyde novolak resin;

between about 37 and about 47% of the epoxidized diglycidyl ether of bisphenol A resin; and

between about 2 and 6 parts by weight of the cationic photoinitiator.

3. The epoxy composition as defined in claim 2 wherein there is between about 25 and about 35 percent of the polyol resin, between about 20% and about 30% of the epoxidized multifunctional bisphenol A formaldehyde novolak resin.

4. The epoxy composition as defined in claim 2 wherein the molecular weight of the polyol resin is between about 60,000 and about 90,000 and the weight per epoxide is from about 30,000 to 45,000;

the molecular weight of the epoxidized multifunctional bisphenol A formaldehyde novolak resin is between about 5,000 and about 7,000 and the weight per epoxide is from about 190 to 250 and the molecular weight of the epoxidized glycidyl ether of bisphenol A is between about 1,000 and about 1,700 and the weight per epoxide is about 500 to 1000.

5. The epoxy composition as defined in claim 4 wherein there is about 28 to 29 parts polyol resin, about 24 parts of the epoxidized multifunctional bisphenol A formaldehyde novolak resin;

about 43 parts of the epoxidized diglycidyl ether of bisphenol A resin;

about 5 parts by weight of sulfonium salt initiator.

6. The epoxy composition as defined in claim 1 wherein there is between about 20 and about 40 percent of the polyol resin, about 0% of the epoxidized multifunctional bisphenol A formaldehyde novolak resin;

between about 60 and about 80% of the epoxidized diglycidyl ether of bisphenol A resin; and

between about 2 and 6 parts by weight of the cationic photoinitiator.

7. The epoxy composition as defined in claim 1 wherein the molecular weight of the polyol resin is between about 60,000 and about 90,000 and the weight per epoxide is from about 30,000 to 45,000;

the molecular weight of the epoxidized multifunctional bisphenol A formaldehyde novolak resin is between about 5,000 and about 7,000 and the weight per epoxide is from about 190 to 250 and the molecular weight of the epoxidized glycidyl ether of bisphenol A is between about 1,000 and about 1,700 and the weight per epoxide is about 500 to 1000.

9. The epoxy composition as defined in claim 1 wherein there is about 28 to 29 parts polyol resin, about 24 parts of the epoxidized multifunctional bisphenol A formaldehyde novolak resin;

about 43 parts of the epoxidized diglycidyl ether of bisphenol A resin;

about 5 parts by weight of sulfonium salt initiator.

10. The epoxy composition of claim 1 wherein the molecular weight of the polyol resin is greater than about 60,000.

14. The epoxy composition of claim 1 wherein the glass transition temperature is greater than 100°

C.

8. The epoxy composition as defined in claim wherein there is about 28 to 29 parts polyol resin, about 24 parts of the epoxidized multifunctional bisphenol A formaldehyde novolak resin;

about 43 parts of the epoxidized diglycidyl ether of bisphenol A resin;

about 5 parts by weight of sulfonium salt initiator.

11. The epoxy composition as defined in claim I further comprising a solvent for said epoxy resin system.

12. The epoxy composition as defined in claim 11 wherein there is a concentration of about 50% solids in the solvent.

13. An epoxy composition as defined in claim 11 wherein said solvent is propylene glycol monoethyl ether acetate.

15. An improved, non-brominated photosensitive cationically polymerizable epoxy composition for use as soldermask comprising:

a. a non-brominated epoxy resin system consisting essentially of;

i. from about 10% and about 80% by weight of a polyol resin which is a condensation product of epichlorohydrin and bisphenol A, having a molecular weight of between about 40,000 and about 130,000 and a weight per epoxide of from about 20,000 to about 65,000;

ii. between about 0% and about 90% by weight of an epoxidized multifunctional bisphenol A formaldehyde novolak resin having a molecular weight of between about 4,000 and about 10,000 and a weight per epoxide of about 180 to 500;

iii. between about 24% and about 85% by weight of a solid epoxidized glycidyl either of bisphenol A having a softening point of between about 60°

C. and about 110°

C. and a molecular weight of between about 600 and about 2,500 and a weight per epoxide of about 300 to 1250; and

b. from about 0.1 to about 15 parts by weight per 100 parts resin system of a cationic photoinitiator capable of initiating polymerization in said epoxy resin system upon exposure to actinic radiation.

16. The epoxy composition as defined in claim 15 further comprising a solvent for said epoxy resin system.

17. The epoxy composition as defined in claim 16 wherein there is a concentration of about 40% solids in the solvent.

18. An epoxy composition as defined in claim 16 wherein said solvent is propylene glycol monoethyl ether acetate.