Design and Construction Affects on PWB Reliability
The author reviews general trends in design like the use of non-functional pads, or nickel as part of the surface finish and overall robustness. Production Floor
Paul Reid
PWB Interconnect Solutions
Nepean, ON Canada
Transcript
The reliability, as tested by thermal cycling, of printed wire boards is established by three variables; copper quality, material robustness and design. The copper quality can be evaluated pretty accurately by microsectioning.
With the advent of Removal of Hazardous Substances causing lead to be removed from solder and the increase in thermal excursions for assembly and rework, materials tend to be as much a problem as copper quality in the robustness of PWBs.
At the new lead free assembly temperatures the materials tend to break down adding to the failure modes caused by lead free assembly. Both the copper quality and material robustness are improving and now PWB designs are beginning to become more influential in the ability to provide a robust board in a lead-free environment.
In this paper the author reviews the general trends in design like the use of non-functional pads, or nickel as part of the surface finish and rank the overall robustness of each.
