Printed Circuit Design & Fab - December 2007 - (Page 36)

SUPPLY CHAIN An OEM Guideline for SELECTING PCB SUPPLIERS When choosing a PCB supplier, site inspection and qualification testing are important, but doing your homework ahead of the facility visit can save time and money. by RENEE MICHALKIEWICZ Many large original equipment manufacturers (OEMs) have a detailed procedure and a significant capital investment in place for the selection of printed circuit board suppliers. This approval process typically involves one or more site audits, which, as we know, now involves a significant amount of overseas travel, and non-destructive and destructive qualification testing by a third-party laboratory. This is all well and good if your company has what seems like unlimited funding to carry out this process, but where does this leave the small OEM? This paper is intended to help smaller OEMs get the most for their money and purchase a quality product. I was recently in a meeting with a new IPC member who was also new to the electronics industry, and he made the following statement regarding qualifying suppliers: “We go to the PCB supplier’s facility for a tour. They take us to lunch, and they are approved.” He also asked in this same meeting: “Where in IPC can I go for help to better understand what I should do?” We did not have a good answer to his question. Within the past year and a half, a blue ribbon committee has been started to assess the feasibility of IPC having a PCB Qualified Suppliers List similar to that of the military for MIL-PRF-31032, MIL-PRF-55110 and MIL-P-50884. This will most likely take a few years before we see this come to fruition. In the interim, this paper will provide some basic guidelines in assessing your supplier’s board at a cost that is reasonable to your company. The OEM begins to report failures of the unit, luckily without the loss of lives. The OEM experiences downtime and flight delays. The OEM is holding the ODM responsible. The ODM receives the failed unit for a complete root cause failure analysis. The analysis of this lot of assemblies and other lots from the same supplier show plating cracks attributed to a copper ductility issue. The ODM visits the PCB manufacturing facility for the first time to review these findings and to audit the facility and discovers that the manufacturer states that it builds to IPC-6012, Class 3, but that it has done none of the qualification, conformance or acceptance testing to verify that its product, indeed, meets the Class 3 requirements. Of course, the ODM can hold the PCB manufacturer responsible but not before enduring numerous court battles and the loss of its largest client’s confidence in them. Could this happen to you? Do you have an approved PCB supplier list? How did you qualify those suppliers? As can be ascertained by the hypothetical case study above, responsibility for purchasing PCBs for assembly and incorporation into an end product must not taken lightly. The Military’s Qualified Products List The military was the first to develop a Qualified Product List (QPL) for PCBs, and much can be learned about developing an Approved Supplier List by reviewing the military process of maintaining a QPL. MIL-P-55110 governed rigid boards and MIL-P-50884, flexible circuits. In the past, the Department of Defense (DoD) was on the forefront of advancing technology. Currently, the commercial industry has taken the lead, and the military is benefiting from these advances. The military has now moved to maintaining a QML or Qualified Manufacturers List. What is the difference between a QPL and a QML? The QPL was geared toward qualifying specific products, based on material type and design complexity. The DECEMBER 2007 Hypothetical Case Study A military/commercial ODM (original design manufacturer) has been supplying Class 3 product to its customers. Its product is incorporated into the guidance system of a commercial airplane. The ODM believes that it has the quality of its circuit boards under control by specifying IPC-6012, Class 3 on its drawings. 36 PRINTED CIRCUIT DESIGN & FAB

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Printed Circuit Design & Fab - December 2007 Contents Our Line Market Watch Around the World Happenings ROI 2007 PCB Designer Salary Survey Interconnect Strategies Positive Plating RF Design Ad Index Noise Reduction Supply Chain DfM Off the Shelf Marketplace The Signal Doctor

Printed Circuit Design & Fab - December 2007

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