Posts Tagged ‘cratering’

Simple Yield Improvement. (Part 2)

Sunday, January 6th, 2013

In the previous post we discussed what happens to the printed circuit board structure when it is heated. We discussed how different materials expand at different rates and the effect the expansion rates have on the warp and twist of a Printed Circuit Board (PCB). We also discussed how moisture absorption can increase the degree of warp and twist and the adverse effect it has on assembly yields and potential field failures. We also discussed how dry baking removes moisture from the PCB and how it minimizes if not eliminates potential problems.

In this post we shall discuss the stabilizing effect that (more…)

What damage does the assembly process do to a pcb? (part 3)

Sunday, August 21st, 2011

In part 2 of this post I explained how the T260 and T288 material data sheet values could be used as an indicator of how durable a laminate system (FR-4) shall be when exposed to heat. The higher the temperature applied the less time it takes to delaminate the FR-4. Traditional dicey cured epoxy systems do not stand up to lead-free assembly temperatures as well as one would think. The newer phenolic cured epoxy systems are much better suited and able to withstand the higher temperatures applied with lead-free assembly techniques.

GREAT! PROBLEM SOLVED!

Not exactly. (more…)

Vendor Spotlight: A solution to pad cratering.

Saturday, April 30th, 2011

Lead-free assembly techniques and practices have pushed the envelope of printed circuit board technology for years. The industry has been forced to change and improve as a result of customer demands and regulatory compliance. Lead-free compliance has been a journey filled with advancement and disaster. The advancement comes in the form of new improved materials and surface finishes. The disaster came in the form of all of the manufacturing non-conformances found along the way and yet to come. Over the past six years the electronics industry has been one giant crucible. Within this crucible we have tested the limits of the process at the bare board and assembly levels.

Prior to lead-free assembly practices there was eutectic solder consisting of tin-lead (Sn63/Pb37). As the saying goes “Nothing solders like solder”. Eutectic solder wicks easily at relatively low temperatures. Solder joints have a unique property where the inter-metallic copper-tin alloy grows over time. There are decades of historical information and observation on the longevity and durability of eutectic solder joints and assembled materials. In a competitive industry where change introduces the potential of non-conformances, eutectic solders are a proven and safe technology.

Enter lead-free assembly. (more…)