Browse Prior Art Database

Elongated Flexible Chip Joint

IP.com Disclosure Number: IPCOM000091630D
Original Publication Date: 1968-Apr-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Miller, LF: AUTHOR

Abstract

This method is for elongating the soldering joints connecting the electrical contacts on a semiconductor chip to conductive lands on a substrate. In structures having semiconductor chip 10 joined to conductive land patterns 11 on ceramic substrate or module 12 by solder pad connections 13, it is desirable to elongate pads 13 so that such joints are subject to a minimum of stress due to thermal expansion within the structure during usage. In order to accomplish this, substrate 12 on which chip 10 is mounted is inverted, as in B, and maintained at a fixed distance above base surface 14.

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Elongated Flexible Chip Joint

This method is for elongating the soldering joints connecting the electrical contacts on a semiconductor chip to conductive lands on a substrate. In structures having semiconductor chip 10 joined to conductive land patterns 11 on ceramic substrate or module 12 by solder pad connections 13, it is desirable to elongate pads 13 so that such joints are subject to a minimum of stress due to thermal expansion within the structure during usage. In order to accomplish this, substrate 12 on which chip 10 is mounted is inverted, as in B, and maintained at a fixed distance above base surface 14.

The structure is then subjected to sufficient heating to cause pads 13 to flow. Due to the weight of chip 10, the joints sag and such chip drops until it is stopped by surface 14 with pads 13 becoming elongated as in C. The structure is then cooled, causing pads 13 to resolidify in their elongated form.

Should the weight of chip 10 be insufficient to cause pads 13 to sag, mechanical devices can be applied to move chip 10 to surface 14. For example, suction can be applied through surface 14 from below to draw chip 10 against such surface. In an alternative process where an additional chip 15 is to be joined to the other side of substrate 12, the elongation of pads 13 can take place simultaneously with the heating step for initially joining chip 15 to the substrate as in D.

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