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Porcelainized Printed Circuit Cards with Conductive Through Holes

IP.com Disclosure Number: IPCOM000049272D
Original Publication Date: 1982-Apr-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 68K

Publishing Venue

IBM

Related People

Cole, AS: AUTHOR [+4]

Abstract

A method is described for eliminating the meniscuc effect on conductive plated through holes in porcelainized printed circuit cards and enhancing fabrication of the holes.

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Porcelainized Printed Circuit Cards with Conductive Through Holes

A method is described for eliminating the meniscuc effect on conductive plated through holes in porcelainized printed circuit cards and enhancing fabrication of the holes.

In a typical porcelainized printed circuit board (Fig. 1) the through holes 1 in the cores 2 when drilled or punched have sharp surface edges 3. Core 2 may be of steel or other metals, such as aluminum. When a glass frit (or other insulating material) 4 is applied, a meniscus 5 is formed because of the sharp edges and the conductor material 6 cannot be properly applied around the holes.

To eliminate this problem, a bevel or radius is introduced on both sides of the holes to eliminate any sharp edges. The beveling process can be done concurrent with the hole punching operation. Other techniques could be used, such as coining, chemical etching or laser drilling.

An individual hole 10 in the core substrate (Fig. 2) is punched or drilled larger than the finished hole to be required. A nesting die 12 with a chamfer 13 and a tip 14 corresponding to the size of required finish hole are used. Tip 14 prevents die punch 16 from making the hole smaller than required. Nesting die 12 is surrounded by a stripper plate 15a, 15b. Die punch 16 has a chamfer 18 with the same angle as chamber 13 in the nesting die and is surrounded by a clamping die 17a, 17b.

Core 11 is placed on nesting die 12 (Fig. 2). Clamping die 17a, 17b (Fig. 3) is moved down...