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Plated Through Via Holes for Discrete Component Mounting

IP.com Disclosure Number: IPCOM000074364D
Original Publication Date: 1971-Apr-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Eidsheim, J: AUTHOR [+2]

Abstract

This method provides a continuous metallic coating for large via holes in multilayer ceramic substrates suitable for mounting discrete components such as resistors or capacitors in a manner similar to that used on printed circuit cards.

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Plated Through Via Holes for Discrete Component Mounting

This method provides a continuous metallic coating for large via holes in multilayer ceramic substrates suitable for mounting discrete components such as resistors or capacitors in a manner similar to that used on printed circuit cards.

Holes of sufficient diameter (40-50 mils) are punched on each green ceramic layer. Corresponding holes are made in a via fill mask for each layer, thus allowing MoMn paste to fill these holes. Due to the large hole area, the paste will adhere to the supporting surface underneath the holes, which can be lined with a paper tape, but sufficient paste will adhere to the hole walls to cover them. Upon lamination and subsequent firing of the ceramic the Mn diffuses into the ceramic providing a continuous MoMn layer firmly bonded to the walls of the via holes. The fired MoMn serves as a basis for a layer of nickel followed by a layer of gold to insure good solderability and to prevent oxidation of the nickel during chip reflow.

To connect a conductor in the substrate to the via metallization, screened lines on internal layers may be extended to the via hole or brought up to the surface of the substrate by a regular via column and connected by screening to the "doughnut" around the subject via hole. Components may be mounted by utilizing solder reflow as done in known printed circuit manufacturing processes.

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