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28 The PCB Magazine • December 2017 • Some suppliers 100% hipot test their ma- terials, some will test them if you request it at an extra cost, and many don't have the ability to test their material • Many suppliers will supply single-sided IMPCB materials. If you are thinking of utilizing multilayer constructions, only a handful of suppliers will supply you cores with high thermally conductive prepreg and thermally conductive prepreg that can be used to bond the multilayer PCBs to the metal • Supply chain ease is important. Lead times vary between the different suppli- ers. Do you want to source in the U.S. and China or just China? If you are interest- ed in doing both regions, choose a suppli- er that has a support structure in both re- gions of the world • Another important factor could be R&D that is being done by the laminate sup- plier. As an example, a couple of laminate suppliers have developed special laminate materials where the aluminum can be bent and formed without compromising the copper circuitry or the dielectric layer Selecting a PCB Supplier It is important to partner with an appropri- ate PCB supplier for your IMPCB needs. Some criteria to consider are: • Level of experience with manufacturing IMPCB materials • A supplier that is educated and has manufactured a variety of different types of IMPCBs and materials from different suppliers • A supplier that has a good relationship with the material suppliers in the space • A supplier that is willing to work in partnership with you keeping an open mind when it comes to your ultimate needs • If UL is important to your application, ensure that the supplier has the requisite UL paperwork • Finally, consider a supplier that has the process controls and disciplines in place Conclusion We have focused this article around the de- signs we see most commonly. We have dealt in a number of situations where people's require- ments for a variety of reasons deviate dramati- cally from these norms. Many other options are possible, so the key is to work closely with your PCB fabricator. As we conclude this discussion of thermal management materials and substrates, it is im- portant to remember that everything in tech- nology is a trade-off. When choosing between the different thermal management substrates it is vitally important to define the end-product in terms of the actual conditions it will experi- ence during its lifetime and deciding which op- tions will be best suited for that product. Final- ly, selecting the right thermal solution is a like a three-legged stool, with the legs being: the end product, the actual design, and the manufactur- ing process—none of which can be ignored to create reliable thermally sound PCBs. Acknowledgements The authors would like to thank Jim Zeman, director of quality, and John Bushie, director of technology, for their work on the white solder mask evaluation. Our discussions with some of our suppliers—Electra, Taiyo, Aismalibar and Vente—helped to shape our thoughts. Finally, we would like to acknowledge all the IMS cus- tomers and designers we have worked with over the years who have challenged us in many ways and helped us grow in this sector. PCB Anaya Vardya is president and CEO of American Standard Circuits. Dave Lackey is vice president of business development at American Standard Circuits. THERMAL MANAGEMENT: A PCB MANUFACTURER'S PERSPECTIVE ON INSULATED METAL PCBS