| Sponsor |
|
Dedicated Tool for Process Development
Advanced plating capability at Uyemura Tech Center: Process Development, UBM, pilot production. ENIG, ENEPIG, EPIG/EPAG, RAIG immersion gold; all substrates. On-site analysis.
Uyemura
|
|
| Sponsor |
|
"Ask the Experts" Program by Circuitnet
Do you have a question or process issue in PCB assembly? The Circuitnet "Ask the Expert's" program has over 100 panel members waiting to answer your question. Submit question now.
Circuitnet Media LLC
|
|
Solder Performance and Reliability Assurance (SPRA) Project
The performance specification of solder requires that any solder being considered meet assembly requirements as well as the interconnects formed with the solder survive specified mechanical shock, thermal cycle, and vibrations environment conditions.
Materials Tech
DOWNLOAD
|
Authored By:
Michael Osterman, Ph.D.
CALCE/University of Maryland
Maryland, USA
Summary
Defense electronics have been traditionally made with tin-lead solder, but the shift to lead-free production in the electronics industry due to government bans on the use of lead is making it difficult to maintain tin-lead solder production. As a result, the majority of electronics are produced with lead-free solder and the electronic components produced for lead-free solder assembly.
To continue tin-lead solder production, the defense electronics manufacturers must assess electronic components for tin-lead assembly compatibility and potentially reprocess components. These processes can compromise component reliability and delay defense electronics production. Despite these challenges, there remains a reluctance to adopt lead-free technology due to uncertainty about its performance and the lack of widely accepted performance specifications for lead-free solder.
To address these challenges, the United States Partnership for Assured Electronics, the Solder Performance and Reliability Assurance (SPRA) project, sponsored by the Cornerstone Other Transfer Activity under CIR CS-20-1302 for Lead-Free Defense Electronics Public-Private Partnership, aims to develop a solder agnostic performance specification and handbook for approving the use of solder in printed board assembly production for defense applications.
The performance specification sets forth the requirements for solder used to form packaged device terminal to printed board interconnects and provides a verification process for the requirements. To support the performance specification and support adoption of new solders, a handbook to address concerns related to solder has also been drafted. This paper will discuss details of the performance specification and handbook.
Conclusions
A review of draft versions of the SPRA performance specification and handbook for solder used in printed board assemblies has been presented. The performance specification of solder requires that any solder being considered meet assembly requirements as well as the interconnects formed with the solder survive specified mechanical shock, thermal cycle, and vibrations environment conditions.
It should be noted that the performance specification does not replace electronic product qualification as the range of loading requirements during the life of an electronic product an vary extensively. As such, the performance specification should be viewed as a threshold to which any solder being considered should held. It should also be clear that extensive knowledge of solder is needed and that industry and academia must continue to play a role in generating data to allow for life expectancy modeling and assignment of physical test acceleration factors to assure electronic product reliability.
The handbook contains knowledge gained from the transition from tin-lead to chiefly SAC305. It has the expectation that any possible solder would be tin based. This is not expected to present a limit as packaged electronic devices are tied to tin copper and tin nickel intermetallics making it unlikely that a non-tin based solder will be introduced. Further, the handbook assumes reflow, wave, fountain and hand soldering will be major processes for printed board assembly.
Initially Published in the SMTA Proceedings
|
Free Newsletter Subscription
Circuitnet is built for professionals who bear the responsibility of looking ahead, imagining the future, and preparing for it.
Insert Your Email Address
|
| Sponsor |
|
Bring IPC Training to Your Facility
Mobile training center offers IPC certified classes at your company’s facility making solder training effective and convenient for your entire team.
BEST Inc.
|
|
|
