Circuits Assembly - August 2008 - (Page 22)

PWB Procurement Auditing a Fabricator By Zulki Khan Guidelines for prototypes and production boards overlap, but for offshore production the rule is caveat emptor. WB procurement can be categorized as either procuring prototype or production boards or both. But the common denominator is both require assurances the fabricator has the capability and capacity to deliver the required quantities on time and with high quality. A PWB order ranging from a few units to a few thousand can be placed with a highly capable and reliable vendor offering excellent pricing. However, if that vendor has capacity issues, meeting OEM product deadlines will create major challenges. Therefore, it is prudent to qualify multiple vendors as a Plan B to avoid PWB purchasing conditions that might arise when relying on a sole supplier. Each case, whether prototype or production, involves distinctly different buying patterns and requirements, and with them, issues OEM purchasers should be aware of. Different parameters are associated with prototype and production PWBs. On one hand, prototypes are smaller in quantity and require faster turnaround, and not all potential problems may be resolved prior to product development. Conversely, production PWBs demand all evident and not-soevident issues be resolved at the outset. And for production boards, turnaround time is less an issue than for prototypes, yet pricing moves from second-tier status to paramount. However, there’s much more to consider than meets the eye. Therefore, OEM purchasers must navi22 Circuits Assembly AUGUST 2008 P gate a tricky, often problematic and challenging path to ensure delivery of high-quality, high-reliability, fully functional PWBs. And a fabricator’s equipment, capability and expertise are foremost considerations. It’s important to perform a detailed audit to determine the age of fabricator’s equipment, especially when procuring prototypes. This is important because newer prototypes push technology limits and mandate faster and better equipment. Outdated equipment can lead to a large assortment of costly problems for leading-edge PCB prototypes, particularly those using the latest components such as fine-pitch BGAs and CSPs. For example, a leading-edge board can require an inordinately high number of vias, especially if used in a handheld product consisting of densely populated components. PCB complexity of this level, for instance, demands advanced drills capable of holes of 0.006" and less with utmost precision to avoid half-moons and drill-to-pad misregistrations. The list below shows a number of key questions to ask the prospective fabricator: • Does it handle cutting-edge technology (e.g., 0.001"-0.002" lines and spaces)? Does it use ULapproved materials? Mixed material? • How new is its equipment? • How often is the equipment calibrated? • Is the company certified for special cases, such as plating heavy (e.g., 4 oz.) copper? • Is it certified by UL, and for what parameters and specifications? • Can it effectively perform flying probe and bed-ofnails testing? • Can it perform via-in-pad technology? • How fine are its drilling capabilities (e.g., 0.003" laser drilling)? circuitsassembly.com http://circuitsassembly.com

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Circuits Assembly - August 2008 Contents Caveat Lector Industry News Market Watch Talking Heads Screen Printing Better Manufacturing Auditing a Fabricatior Cutting Machine Programming Time Simultaneous Acoustic Imaging and Surface Mapping Tech Tips Soldering Test and Inspection Process Doctor Pb-Free Lessons Learned Getting Lean Component Advances Product Spotlight Ad Index Assembly Insider Techincal Abstracts

Circuits Assembly - August 2008

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