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Method for a serrated pin structure for wave soldered heatsink pins

IP.com Disclosure Number: IPCOM000010060D
Publication Date: 2002-Oct-16
Document File: 2 page(s) / 71K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a serrated pin structure for wave soldered heatsink pins. Benefits include improved reliability.

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Method for a serrated pin structure for wave soldered heatsink pins

Disclosed is a method for a serrated pin structure for wave soldered heatsink pins. Benefits include improved reliability.

Background

              Weak mechanical strength causes reliability failures due to an electrical open for wave soldered heatsink pins. Cracks, which are detected post-assembly, initiate from the primary side of the pins at eutectic Sn-Pb solder to Cu-Sn intermetallic compound (IMC) interface. Propagation occurs along this interface at a relatively fast rate compared to other through-hole mount (THM) connectors or e-caps, due to the large heatsink structure. The conventional smooth pin structure does not present an obstruction to deter crack propagation (see Figure 1).

      Conventionally, careful handling of the wave solder heatsink minimizes mechanical bending due to compression stress, but this requires increased operator training.

Description

              The disclosed method is a serrated heatsink pin structure that enhances mechanical strength (see Figure 2). The key elements of the method include:

•             A serrated pin structure for the wave soldered heatsink pins

•             An interlocking effect between the solder and IMC layer that prohibits mechanical cracking due to bending or compression stress

      The pin temperature (from 70oC to ~120oC) during the wave process enhances wetting of the pin coating layer when wave soldered, producing a homogenous eutectic Pb-Sn mi...