EPSI INC.  -  Electronics Packaging Solutions International Inc.
P.O. Box 1522, Montclair, NJ 07042 USA, tel.: +1 (973)746-3796, fax: +1 (973)655-0815
Electronic circuit board assemblies may be subject to significant thermal and mechanical loads when powered on and
off or under high temperature, shock & vibration as in automotive, underhood electronic modules.  In some
applications (e.g., aerospace), circuit boards are expected to survive 20 to 40 years of field use or tens of thousands
of off/on cycles.  In other applications, assembly reliability is life- or mission-critical (e.g., pacemakers, jet engines).  
While boards and components are failure-prone, all with their own failure modes, solder joints remain the weakest
link of electronic assemblies.

Solder joints, those tiny metallic "dots" that are used to attach components onto a circuit-board, have been described
as the "glue" of electronic assemblies.  Solder interconnects are likely to fail under repeated loads and deformations
Examples of cracked solder joints).  This may lead to electrical opens in mission-critical circuitry.  The challenge
is to make sure that solder joints survive the intended design life.  When they fail, we look for the root cause of the
problem and recommend design changes and/or corrective actions.

With over 50 years of experience using tin-lead (SnPb) solders, the industry has a good grasp of SnPb reliability and
of what works and what does not work.   Field failures of SnPb circuit boards are usually the result of poor
soldering workmanship or a lack of proper design-for-reliability, whereby reliability was poorly addressed during the
design phase.

With the advent of lead-free (Pb-free) electronics, new solder materials are being introduced as a replacement for
conventional tin-lead (SnPb).  While no single drop-in replacement has been identified, solders in the tin-silver-copper
(Sn-Ag-Cu) family are likely to become alloys of choice.  With very little field experience, and a multiplicity of
competing alloy compositions, industry is faced with the daunting task of establishing the reliability of Pb-free
assemblies under tight deadlines - prior to July 1, 2006 for electronic products being shipped within or into the EU.  

EPSI Inc. has been actively involved in the study of Pb-free solder materials and  Pb-free solder joint reliability for
over ten years.  We offer training seminars and consult with clients on the impact of the Pb-free conversion on
product reliability.
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Copyright EPSI Inc. 2003-2006.