Heatsink and package structures with fusible release layer

US6084775A · kind A · utility

Assignee

• International Business Machines Corporation · US

Inventors

• Gerald K. Bartley · Rochester, US
• Douglas A. Baska · Oronoco, US
• James D. Bielick · Pine Island, US
• Matthew A. Butterbaugh · Rochester, US
• Mark K. Hoffmeyer · Rochester, US
• Sukhvinder S. Kang · Concord, US

Key dates

• Filing date: Dec 9, 1998
• Grant date: Jul 4, 2000
• Expiry date: Dec 9, 2018

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01L2924/14
• WIPO field: Semiconductors
• WIPO sector: Electrical engineering

Abstract

Aluminum heatsinks are plated with a solderable layer and are overplated with a solder release layer. The release layer comprises a tin-lead-indium alloy. The heatsinks are mounted on individual IC modules or banks of IC modules that are interconnected to a printed circuit card. A mechanically compliant, thermally conductive adhesive is used to join the heatsinks to the modules. An oxide formed on the release layer readily bonds with the thermally conductive adhesive. In the event that heatsinks need to be removed to repair or rework the modules, local heat may be applied to melt the release layer to remove a heatsink without need for use of significant applied torque and normal forces. Because the release layer has a low melting point that affords easy separation from the adhesive layer, both component delaminations and the partial reflow or melting of solder joints on adjacent components are eliminated from the heatsink removal process.