Browse Prior Art Database

Indium Lead Indium Chip Joining

IP.com Disclosure Number: IPCOM000090425D
Original Publication Date: 1969-Apr-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Dawson, WA: AUTHOR [+3]

Abstract

This process is for attaching a semiconductor chip to a substrate. The process first employs a flash evaporation technique for coating conductor 10 of chip 11 with indium. Then a layer of lead 12 is evaporated over the indium and the lead is then coated with another layer of indium. Next, chip 11 is positioned on a substrate, not shown, with the indium-lead-indium sandwich thus formed providing the connection between the substrate's conducting lands and chip 11. The substrate and chip 11 are then placed in a furnace and are heated to a temperature intermediate the melting points of indium and lead so that the indium adheres to the lands on the substrate and conductor 10 of chip 11 while alloying with the surface of the lead.

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Indium Lead Indium Chip Joining

This process is for attaching a semiconductor chip to a substrate. The process first employs a flash evaporation technique for coating conductor 10 of chip 11 with indium. Then a layer of lead 12 is evaporated over the indium and the lead is then coated with another layer of indium. Next, chip 11 is positioned on a substrate, not shown, with the indium-lead-indium sandwich thus formed providing the connection between the substrate's conducting lands and chip 11. The substrate and chip 11 are then placed in a furnace and are heated to a temperature intermediate the melting points of indium and lead so that the indium adheres to the lands on the substrate and conductor 10 of chip 11 while alloying with the surface of the lead. As the lead does not melt during the heat cycle, this alleviates the problem of chip collapse onto the surface of the substrate while forming a strong ductal bond between the chip and the substrate. The process can be modified so that the higher melting point metal, lead, is evaporated onto the semiconductor chip's conductor, and then the surface of the lead is coated with indium. Tin can be employed as the low-melting lower or bottom layer in lieu of the indium.

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