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SOLDER COATED BALL TO SEAL PLATED THROUGH HOLES IN GLASS PLATE

IP.com Disclosure Number: IPCOM000005475D
Original Publication Date: 1983-Mar-01
Included in the Prior Art Database: 2001-Oct-08
Document File: 1 page(s) / 54K

Publishing Venue

Motorola

Related People

Steven C. Moore: AUTHOR

Abstract

When glass plate is used to package electrical components such as pressure transducers, resonators, displays or semiconductors, one of the problems is obtaining hermetic electrical connec. tions through the glass sheet. A logical method is to laser drill or etch holes in the glass and then metallize through the hole. After the glass package is assembled, it can be evacuated through the hole and then sealed by filling the hole with solder. The main problem with this solution is that the solder, having a different coefficient of expansion than the glass causes cracks in the glass during d temperature cycling and/or during cooling of the solder after the initial sealing.

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$3, MOTOROLA Technical Developments Volume 3 March 1983

SOLDER COATED BALL TO SEAL Q,LAT,BD-THROUGH HOLES IN GLASS PLATE

By Steven C. Moore

   When glass plate is used to package electrical components such as pressure transducers, resonators, displays or semiconductors, one of the problems is obtaining hermetic electrical connec. tions through the glass sheet. A logical method is to laser drill or etch holes in the glass and then metallize through the hole. After the glass package is assembled, it can be evacuated through the hole and then sealed by filling the hole with solder. The main problem with this solution is that the solder, having a different coefficient of expansion than the glass causes cracks in the glass during

d temperature cycling and/or during cooling of the solder after the initial sealing.

   The present method uses solder coated silver balls to hermetically seal the plated-through holes (see attached drawing). There are two key advantages to this method: 1) Most of the hole is covered by the silver ball, and 2) the balls can be located in the holes with a negligible cost in labor or equipment by pouring an excess of balls onto the glass plate and rolling them around until one ball has seated itself in each hole. The excess balls are then poured off by tipping the glass plate about 25' from horizontal. In some applications silver might be replaced by a less expensive metal or a metallized non- metal sphere. The small amount of solder used i...