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The European Unions Restriction of Hazardous pcb board Substances (RoHS)directive, along with other environmental regulations worldwide have been driving changes throughout the supply chain, with printed circuit board (PCB) manufacturers feeling the pain intensely.
In the fabrication and assembly of PCB, RoHS requires the elimination of six hazardous materials lead, pcb board mercury, cadmium, hexavalent chromium, polybrominated biphenyls and polybrominated diphenyl ethers from the production process.
The elimination of lead alone from the solder used for board manufacturing and assembly is forcing a number of changes in processes, raw materials, components and equipment, according to Tony Garramone, corporate training manager at Advanced Circuits, an Aurora, Colo.-based pcb board supplier.
For most board manufacturers, the major change from RoHS will be the use of laminate materials that can withstand higher processing temperatures and different final finishes.
"Until now, laminates with the ability to endure higher temperatures were not in great demand but because the RoHS-compliant materials behave differently, there will be a number of process changes necessary to effectively process pcb board panels with the higher thermal capacity,"
Garramone explained.
Changing laminates also affects drilling processes. Higher thermal laminates require variations in drill feed and speed rates C with these changes possibly increasing processing time.
Then, after the drilled holes have been cleaned and deburred, the panels move on to de-smear and electroless processes. Here, too, higher thermal capacity laminates set themselves apart from the norm, requiring longer dwell times and potentially higher temperatures. Depending on the laminate material, special processing such as plasma etchback may be needed.
All of these variables present the possibility of additional time requirements and the need for unique processes that PCB manufacturers must install and maintain.pcb board
Another issue confronting PCB manufacturers is the use of a solder for lead-free production. The leading candidate is a tin copper alloy due to its processing temperature of 260 degrees Celsius. This temperature is nearly identical to the temperature of processes currently running on many leaded machines, seen as a huge benefit, since much of the same tools and equipment can be used.
In an effort to stay ahead of the curve, Advanced Circuits recently made available a lead-free solder as a plating finish for an enhanced solderable finish for assembly that meets RoHS requirements without a price increase.
A further area of concerns regards fracturing on the pcb board themselves. It seems that these materials should present a relatively benign addition to these final processes but there have been indications that bare board test equipment probes may see a shorter life span. Left on the test probes, tin residue from lead-free solders can cause considerable damage. And some of the optional surface coatings are susceptible to damage from test pins or probes.
Along with processing issues, other problems must be addressed, including traceability/tracking and training. "The ability to identify pcb board specific lots of raw materials, as well as manufacturing process dates and times, is needed to substantiate lead free claims," Garramone said.
PCB manufacturers need to certify that its products are indeed RoHS compliant. To do that, PCB suppliers and vendors must offer assistance in maintaining supplies that are backed by certificates of conformance and test data.
Finally, knowledgeable employees in all part of the PCB plant are a necessity. Beginning with the sales staff, there must be a certain level of understanding as to what RoHS compliance is, what is necessary to produce a lead free order pcb board and what questions should be answered to understand exactly what a customer needs or wants. Any employee who reviews orders, reads drawing packages, creates process travelers or deals with production processes must be aware of the requirements. Training the staff to recognize the differences, the materials and processes required to meet customers needs is a priority.
PCB manufacturers have always had the challenge pcb board of meeting the specifications for a wide range of customers, and with RoHS, that challenge is multiplied.
"All PCB manufacturers, whether assembling 100 boards a month or 100 an hour, have one thing in common: pcb board They all have new responsibilities to create RoHS-compliant products on behalf of the customer," Garramone concluded.
