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Solder Ball Connection Tensile Pull Test Method

IP.com Disclosure Number: IPCOM000107993D
Original Publication Date: 1992-Apr-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 2 page(s) / 59K

Publishing Venue

IBM

Related People

Puttlitz, KJ: AUTHOR [+2]

Abstract

Lead rich, lead-tin solder balls (typically 90Pb-Sn) are attached to substrate as a part of the I/O in Solder-Ball-Connection (SBC) modules with Pb-Sn eutectic solder. The joint integrity must be monitored via tensile loading to assure reliability. Since the solder ball is very soft, it can not be gripped mechanically and tensile pulled without causing deformation. This disclosure provides a technique to perform tensile-pull testing on SBC modules.

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Solder Ball Connection Tensile Pull Test Method

       Lead rich, lead-tin solder balls (typically 90Pb-Sn) are
attached to substrate as a part of the I/O in Solder-Ball-Connection
(SBC) modules with Pb-Sn eutectic solder.  The joint integrity must
be monitored via tensile loading to assure reliability.  Since the
solder ball is very soft, it can not be gripped mechanically and
tensile pulled without causing deformation.  This disclosure provides
a technique to perform tensile-pull testing on SBC modules.

      As shown in the figure, solder paste 4 is screened onto studs
5, such as copper studs, which may be tinned.  The selected solder
paste must be such that upon subsequent reflow its mechanical
strength is greater than the SBC lead-tin eutectic solder 2 since the
joint located between the solder ball and substrate is the one
tested.  The following solders are offered as acceptable examples,
but the choice not limited to them:  62Sn-Pb eutectic solder,
46Bi-34Sn-20Pb, 70Sn-18Pb- 12In.  Studs with solder paste are placed
into the holding fixture 6.  The SBC balls 3 facing downward on a
substrate 1 are made to mate with the screened solder pads 4 on studs
5.  The holding fixture containing both substrate and studs is heated
in a suitable manner to reflow the screened solder paste (e.g.,
furnace reflow with a 5 + 3 or -3 minutes dwell), followed by a
flux-clean operation.  The joint can now be tension tested utilizing
a tool, such as made by Instron Inc....