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Screenable Epoxy Anhydride System for Printed Circuit Boards

IP.com Disclosure Number: IPCOM000094467D
Original Publication Date: 1965-Feb-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Troxell, RH: AUTHOR

Abstract

An epoxy-anhydride composition as a protective coating for printed circuit boards is characterized by using a trimellitic anhydride as a curing agent.

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Screenable Epoxy Anhydride System for Printed Circuit Boards

An epoxy-anhydride composition as a protective coating for printed circuit boards is characterized by using a trimellitic anhydride as a curing agent.

The composition is a two component system in which the formula of part 1 is as follows: EPON* 1001 75 grams EPON* 1007 75 grams TMX-220** anhydride ester 46 grams BENTONE*** #34 20 grams Acetone 25 ml Methyl Isobutyl Ketone 69 ml Butyl Cellosolve Acetate 60 ml. Part 2 has the following formula: UNOX**** 201 molecular weight 380 100 grams Butyl Cellosolve Acetate 30 ml.

The constituents of part 1 are blended to obtain a uniform mixture. The constituents of part 2 are blended with part 1 just prior to coating the mixture onto the printed circuit boards. The coating can be applied by silk screening techniques. After a curing cycle is completed, the coating serves as a solder mask and as a final protective coating.

The coatings made from the above composition have the advantages of a one hour cure cycle at 335 +/- 5 degrees F as opposed to the normal four hours required by other compositions, no apparent breakdown or solder ball pickup when the printed circuit board is wave soldered at 500+/- 10 degrees F, and no vacuum cycle is necessary for bubble release, since the coating is generally bubble free. * Trademark of Shell Chemical Co. ** Product of Amoco Chemical Co. *** Trademark of National Lead Co., Baroid Div. **** Trademark of Union Carbide.

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