Browse Prior Art Database

Chip To Terminal Interconnection Technique

IP.com Disclosure Number: IPCOM000075839D
Original Publication Date: 1971-Nov-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Lavanant, F: AUTHOR [+2]

Abstract

As shown in Fig. 1, the electrical connection from the upper contact, typically a metallic ball 10, of a semiconductor chip 11 to a connection pin 12 which has been previously inserted, then swaged in an insulating ceramic substrate 13, is made by using a strip 14. Bending the pretinned strip, with the pretinned ball 10 and the connection pin 12, is carried out in a furnace or by thermocompression. The semiconductor chip 11 is backside mounted onto the ceramic substrate 13 by soldering, brazing or the like 15.

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Chip To Terminal Interconnection Technique

As shown in Fig. 1, the electrical connection from the upper contact, typically a metallic ball 10, of a semiconductor chip 11 to a connection pin 12 which has been previously inserted, then swaged in an insulating ceramic substrate 13, is made by using a strip 14. Bending the pretinned strip, with the pretinned ball 10 and the connection pin 12, is carried out in a furnace or by thermocompression. The semiconductor chip 11 is backside mounted onto the ceramic substrate 13 by soldering, brazing or the like 15.

The strip 14 must provide mechanical properties and in particular must be sufficiently flexible to avoid detrimental strain effects at bonding locations. The metal to be used to implement the strip must have a thermal expansion coefficient approximating that of the ceramic substrate; chromium and molybdenum are suitable, provided they are coated with a metal layer (CriCu-Au) to make them compatible with the tin-lead solder.

More simply, some binary or ternary alloys (NiFe, NiFeCo, for example) are directly usable in this application. Another characteristic lies in the particular shape of the strip. Fig. 2 illustrates two differently shaped strips (14a and 14b). The finned design has two functions: to improve the thermal dissipation and to limit the solder reflow under the strip.

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