We've just come through one of the hottest summers in recent history. Temperatures around the world set records as the mercury on thermometers soared. Scientists reminded us that the increases seen in global warming in the past few years is actually a measure of our success in cleaning up the pollution in the air - so more UV radiation can penetrate the atmosphere and heat up the planet. Great work everybody!

Other than higher temperatures, what else has this summer brought? Since the official launch of RoHS on July 1, we have begun to feel the burn - and not just from rising air temperatures. We are getting the proverbial baptism by fire as we race to understand the idiosyncrasies that this significant technology shift has created. In the wake of our best efforts at compliance we find a myriad of processing problems as we see that it takes more than a change in the design, laminate or final finish to be successful. We are experiencing a fundamental shift in the shape and size of the processing window. The well-known collection of interwoven specifications and design rules has been impacted. And because the design, manufacture and assembly of the electronic interconnect is a sequential process, cohesive and interdependent, we need to re-examine them as a set. Communication among the interconnect disciplines has never been more critical.

In the past 60 days, as facilities came on-line with full lead-free production, the industry has seen a marked rise in the number of failures at assembly. We can attribute the increase in rejects to the higher level of stress placed on the system because of higher soldering temperatures, but that does nothing to restore our yields. This may come as no surprise, but one thing is clear, our ability to react and quickly resolve these problems will test our fundamental understanding of the interdependence of the entire manufacturing process. To be successful we need to apply basic root-cause analysis techniques across the entire design, manufacture and assembly disciplines and this will be a challenge for many companies.

What has been documented over the past few months is dramatic - the untold cost of RoHS compliance. Numerous parties report significant increases in blowholes. These increases vary from a few percentage points to double-digit hikes. With the increase in blowholes comes ballooning solder fillets and poor hole fill. There are cases of copper voids and etch-outs along the non-soldermask-coated areas of conductors, sometimes significant enough to reduce the line width and affect the impedance and current-carrying capacity of the circuit - disrupting what we thought had been properly designed. The net result is a negative impact on the performance of the board. And it doesn't end there.

Each story has its unique set of corroborating circumstances. The size and shape of the pads have an effect. Many are considering modification of pad shape and size to improve solder spread. The size of the lead in relationship to the finished hole size contributes. In one case the laminate material selection (Tg) was a contributor, in another it was the degree of cure of the laminate. In still another case it was linked to the soldermask cure. Hole wall roughness contributes. The thickness of the electrolytic copper is a factor. Sometimes the surface finish selection contributes, and still other times the specific formulation of the lead-free solder used in the wave soldering bath is a contributor. The point here is that there is no single contributing cause. In every case the majority of these issues alone would not have contributed to blowholes in a lead-based soldering operation but in the lead-free world the level of rejects rises dramatically.

So what can we do? Brush up on our problem-solving skills and open the lines of communication from assembler to fabricator and designer. Include the suppliers from both the bare board and assembly sides. Processes that are more robust may be required. Better manufacturing practices may need to be adopted. What is clear is that we need to do some things differently from the way we were doing them on June 30, 2006, because as of July 1 that world ceased to exist and a new one took its place. There are new rules of engagement that we are just beginning to understand. We need to react quickly if we are to avoid high scrap rates and rework levels - not to mention the corresponding hit to profitability.