International Business Machines Corporation

Lawrence R Daley

Frederick R Christie

Gerald G Leslie

Transfer printing from pad (9) is made in a pattern of resist (15) which covers a via (3) on a circuit board (1) metalized with a continuous copper layer (7). After transfer of resist material (14) to the pad, the pattern on the pad is hardened enough to be self-supporting by applying moderate radiation or allowing solvent to escape from the resist on the pad. The resist is transferred from the pad to the circuit board (1) and is then fully hardened, and the circuit board is immersed in etchant to remove unprotected copper (7). Copper in the covered vias is protected and therefore separate metalizations of vias is avoided. Since pad printing is particularly useful in general with three dimensional circuit boards, the use of pad printing to avoid separate metalization of vias is economic since it involves little additional to the general use.

Pad printing of resist over via holes

A composition suitable for making circuit boards containing a bismaleimide triazine polymeric component, a brominated epoxy polymeric component, and a solvent is provided.

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Lexington, KY, United States of America

Lawrence R Daley