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Socket Stress Relief

IP.com Disclosure Number: IPCOM000101505D
Original Publication Date: 1990-Aug-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Coulis, PA: AUTHOR [+2]

Abstract

An alternate method is described for the retention of pin barrels into the FR4 body of interstitial sockets.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 88% of the total text.

Socket Stress Relief

       An alternate method is described for the retention of pin
barrels into the FR4 body of interstitial sockets.

      Some interstitial sockets contain over 300 pins currently being
used and arranged in a dense 100-mil interstitial spacing.  The
manufacture of such sockets includes press-fitting pins into
pre-drilled holes of FR4 material.

      Several problems arise with this manufacturing technique.
First, internal stresses arise due to the pins being press-fitted
into the FR4, causing bowing of the socket.  Secondly, when the
sockets are inserted in the panel during card assembly, pin pushout
frequently occurs where the pins pop out of the FR4, causing
connection problems with the corresponding modules.  This occurs even
though the pins are barbed as shown in Figure 1.  Pin pushout is
especially troublesome during the rework process when the FR4 softens
due to the elevated temperatures that the socket is subjected to in
the solder fountain.

      This article provides an alternate method of pin retention.
Barbs are replaced by a continuous thread, as shown in Figure 2, to
provide the following advantages:
      1.   Reduces uneven stress in the FR4 housing.
      2.   Reduces or eliminates socket bowing.
      3.   Reduces/eliminates travel of moisture between the
      socket body and the outer surface of the pin barrel that
      occurs during wave solder and the aqueous cleaning
     ...