A Reliability Examination Of Lead-Free Quartz Crystal Products Using Surface-Mount Technology Engineered For Harsh Environments

By Todd H. Treichel, CQE, Wi2Wi LLC

ABSTRACT

Companies throughout the electronics industry are being asked to design and manufacture products that conform to the newly written Restriction of Hazardous Substances (RoHS) regulations written by the European Commission (EC). Compliance to this legislation requires that products be free of any applicable banned substances. The most prevalent of these banned substances is lead (Pb), which is found in solder.

As the electronics industry moves toward the implementation and use of lead-free solders, very little is known about the reliability of quartz crystal controlled products of lead free construction. Such products include quartz controlled crystals, filters, and oscillators which demand high reliability in a variety of space, military, automotive, and commercial applications.

Quartz crystal products are used in numerous space and military applications, which mandate compliance to specified military test profiles. Therefore, reliability test profiles were selected from MIL-STD-202 and MILSTD- 883 test documents in an effort to apply stress conditions that accelerate potential failure mechanisms and to gain a better understanding of any detected failure modes. In addition, these two test method documents are internationally recognized and applicable in testing military grade electronic component and microcircuit devices for high reliability and/or harsh environment applications.

Selected quartz crystal products were tested for lead-free solder compatibility (utilizing 96.5Sn/3.0Ag/0.5Cu lead free solder paste), and the ability to successfully meet design requirements and reliability test profiles. Under the conditions of this analysis, RoHS quartz crystal technology tested herein, showed no change in performance or degradation and proves to be reliable for applications in harsh environments.