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SURFACE MOUNT REFLOWABLE INDIVIDUAL SOCKETS

IP.com Disclosure Number: IPCOM000006785D
Original Publication Date: 1993-Mar-01
Included in the Prior Art Database: 2002-Feb-01
Document File: 1 page(s) / 50K

Publishing Venue

Motorola

Related People

Roy A. Stone: AUTHOR [+3]

Abstract

Leaching of the lead pads due to repeated reflow temperature exposure. While initially reflowing the cir- cuit board (hybrid) the lead pads are exposed to reflow temperatures. When the leads are attached the lead pads are again#exposed to reflow temperatures when the hybrid is "dipped" into a solder pot (an uncontrolled process). When the circuit board is attached to the mother board the leads, which were attached by dipping, are inserted into through holes in the mother board and the entire assembly is wavelme soldered. This once again exposes the lead pads to reflow temperatures. This triple expo- sure to reflow temperatures contributes to a weakening of the lead pad attachment to substrate known as "leaching? These now potentially weakened bonds are further stressed during subsequent processing when the circuit boards with lead attachments are "bent" out of the way to gain access to adjoining areas.

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MOTOROLA INC. Technical Developments Volume ia March 1993

SURFACE MOUNT REFLOWABLE INDIVIDUAL SOCKl3S

by Roy A. Stone, Kenneth J. Storts and Miroslaw W. Chmiel

THE PROBLEM:

  Leaching of the lead pads due to repeated reflow temperature exposure. While initially reflowing the cir- cuit board (hybrid) the lead pads are exposed to reflow temperatures. When the leads are attached the lead pads are again#exposed to reflow temperatures when the hybrid is "dipped" into a solder pot (an uncontrolled process). When the circuit board is attached to the mother board the leads, which were attached by dipping, are inserted into through holes in the mother board and the entire assembly is wavelme soldered. This once again exposes the lead pads to reflow temperatures. This triple expo- sure to reflow temperatures contributes to a weakening of the lead pad attachment to substrate known as "leaching?

  These now potentially weakened bonds are further stressed during subsequent processing when the circuit boards with lead attachments are "bent" out of the way to gain access to adjoining areas.

THE SOLUTION:

  By using the surface mount individual sockets the lead pads will only be exposed to reflow temperatures once, during initial reflow. There will be no lead attach- ment heating from "dipping" or from attachment to mother board during wavelme soldering. Furthermore, if it is necessary to move the hybrid out of the way to gain access to adjoining areas of the mother board, the hyb...