Browse Prior Art Database

Tin-Antimony Solder Process for Packaging I/O Interconnections

IP.com Disclosure Number: IPCOM000122464D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 2 page(s) / 63K

Publishing Venue

IBM

Related People

Lombardi, TE: AUTHOR [+5]

Abstract

Disclosed is a process for joining I/O pins to multilayer ceramic substrates by using tin-antimony solder (95% Sn-5% Sb).

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 57% of the total text.

Tin-Antimony Solder Process for Packaging I/O Interconnections

      Disclosed is a process for joining I/O pins to multilayer
ceramic substrates by using tin-antimony solder (95% Sn-5% Sb).

      Traditionally, gold-tin (Au-20% Sn) braze alloys have been used
to join pins to the I/O pads of substrates.  Use of tin-antimony
solder to replace the gold-tin braze alloy has several advantages.
Cost of the solder alloy is much lower than the gold-tin braze.
Joining temperature can be reduced, since the liquidus temperature of
the tin-antimony solder (240~C) is less than the melting point of the
gold-tin eutectic (280~C), and less superheat is necessary to form a
good joint.  This is useful for applications in lower temperature
packages involving polymer systems.

      The elastic modulus of the tin-antimony solder is lower than
that of gold-tin braze, so this material can be used in applications
where it is necessary to transfer less stress to the substrate
material yet still produce adequate joints. (For example,
glass-ceramic substrates have lower intrinsic strength than alumina
materials and a low modulus solder may be useful for joining pins to
that system.)

      The actual solder process involves reflowing the tin-antimony
solder material between a pin and substrate so that a bond is formed
joining the pin to the I/O pad.  The solder used for this application
can be in the form of balls, preforms or paste.  The solder and
proper flux can be used with...