Accession Number:

ADD014112

Title:

LED Soldering Method Utilizing a PT Migration Barrier.

Descriptive Note:

Patent, Filed 22 Dec 87, patented 4 Apr 89,

Corporate Author:

DEPARTMENT OF THE AIR FORCE WASHINGTON DC

Personal Author(s):

• Tihanyi, Peter L.
• Vollmer, Hubert J.
• Mott, Jeffrey S.

Report Date:

1989-04-04

Pagination or Media Count:

4.0

Abstract:

Method of bonding a chip to a Cu heat sink comprises depositing a layer of Ni upon the sink, depositing a layer of Pt over the NI, and thereafter annealing the sink in a partial vacuum containing a reducing gas. After the annealing step, a metallic wetting layer of Au and a layer of In are sequentially deposited upon the Pt, and the chip is soldered to the heat sink by means of a flux free soldering process. The pure Pt is very dense and stable, does not have microholes therein which would otherwise allow the Cu ions to penetrate the Pt. For a BeO heat sink, a Ti layer is deposited over the sink rather than Ni, and a layer of Pt is thereafter deposited over the Ti layer. The Ti, Pt and BeO interact to form a good bond of high thermal conductivity, which also blocks ion migration upwardly toward the solder and the electronic chip. PAT-CL-228-124. jes

Descriptors:

• *PLATINUM
• *SOLDERING
• ANNEALING
• BARRIERS
• CHIPS(ELECTRONICS)
• FLUX(RATE)
• HEAT SINKS
• HIGH RATE
• IONS
• LAYERS
• METALS
• THERMAL CONDUCTIVITY
• VACUUM
• WETTING

Subject Categories:

• Metallurgy and Metallography

Distribution Statement:

APPROVED FOR PUBLIC RELEASE