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Smear Removal from Printed Circuit Boards

IP.com Disclosure Number: IPCOM000051743D
Original Publication Date: 1981-Mar-01
Included in the Prior Art Database: 2005-Feb-10

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Related People

Blanchette, PE Carpenter, RW Fisher, RL Meyer, K [+details]


The removal of epoxy smear from drilled holes presents several difficulties, such as copper or epoxy etch back, undercutting, and redisposition of epoxy. These can be avoided by using a caustic, organic-aqueous mixture for cleaning the through-holes after a drilling operation. The drilled panels are first immersed in a mixture, such as stripper A-150 from Enthone, Inc., at 190 degrees F for approximately two minutes. This mixtur serves as an epoxy resin wetting agent. The panels are then dipped in a 10% hydrochloric acid solution and followed by immersion for approximately 2 minutes in a sodium chlorite and sodium hydroxide mixture at 190 degrees F.