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Priming Via Hole Surfaces

IP.com Disclosure Number: IPCOM000086222D
Original Publication Date: 1976-Aug-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Bakos, P: AUTHOR [+2]

Abstract

In certain applications, it is necessary to place circuitry on both sides of a baked ceramic substrate. With such structures, it is desirable to communicate between the circuitry on the two surfaces by means of conductors in via holes. If an attempt is made to plate copper in the via holes, the copper will not stick to the surfaces of the holes and the copper plug could fall out of the holes.

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Priming Via Hole Surfaces

In certain applications, it is necessary to place circuitry on both sides of a baked ceramic substrate. With such structures, it is desirable to communicate between the circuitry on the two surfaces by means of conductors in via holes. If an attempt is made to plate copper in the via holes, the copper will not stick to the surfaces of the holes and the copper plug could fall out of the holes.

The method described below can be used to prime the surface of the via holes so that the copper plug will adhere. The method includes the following steps: 1. Prime the surface of the via holes by depositing a thin film of either iron or palladium. Iron can be deposited by a conventional electroless deposition process. Palladium can be deposited by screening diluted palladium paste into the holes. 2. Place small balls of copper on top of the via holes and heat such that the copper flows down into the via holes. 3. Machine the surface of the via holes so that they are level with the surrounding area. 4. Deposit circuitry by chrome-copper-chrome metallurgy in the normal manner. 5. Small pins can be brazed to the surface of the filled via holes.

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