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PCBD-Jan2015

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24 The PCB Design Magazine • January 2015 Martyn Gaudion is Ceo Polar Instruments. To contact him, click here. er volume and specialist commercial vehicles. From the PCB industry perspective, a rever- sal in oil prices must surely feed through into lower raw material and transport costs; the only downside could be if the fall is so sharp as to disrupt the economy in an unexpected way. However historically lower oil prices feed through into growth, and for the environmen- tally minded the lower oil price also buys more time to look for realistic alternate ener- gy sources in the event that prices flow back up again. Watching the Signals Whilst looking ahead from a signal integrity perspective, just as in other areas, there seems to be a desire to model more and measure less. Measurement has not gone away; it's just that bet - ter modeling tools give every- one a chance to get it right the first time. Measuring in the multi- gigahertz arena is always going to be more costly than at lower frequencies, but what surprises the fabricators more than the price of the instrumentation is that the accessory costs (cables probes, etc.) become an ever-larger (and more delicate) slice of the investment pie when moving to a higher bandwidth test. No doubt as volumes increase the situation will improve, but the laws of physics dictate that fine-pitch probing and low-loss cabling are nev - er going to be as low cost to source as tools for the MHz arena, but perhaps this is an area where I would be pleased to have an incorrect forecast. Insertion loss measurement is a challenging are- na, not least because the industry has yet to con- verge on a single method. There are many ap- proaches all with strengths and limitations, and the fabricator and OEM need to choose carefully between test speed and capability, and also how much real estate on the panel is sacrificed for coupon provision. Materials qualification is a lower volume or "one-time" activity, and may favour more real estate on the coupon, possibly with a four-port VNA measurement post-processed through a technique such as Delta L, or a four-port TDR approach such as SPP. For high-volume test and minimum coupon size and a two-port method minimising equipment investment is the vol - ume test method of choice at present. I recently conducted a comparative study of surface finish- es with a variety of passivating coatings from SN to AG to ENEPIG and some other newer chem- istries, I hope to be able to share more on this as the year unfolds. The study was easy to set up and the comparative insertion loss measure- ments rapidly made with the mini- mum of setup by utilising the SET2DIL method. Expect some enhancements in all methods as the year progresses, and as time passes I am confident the industry will start to converge on a small number of proven methods which will drive down the cost of GHz test for the fabrication industry. Supply chain manage - ment is increasingly relevant from the high-speed perspec- tive; I hear more and more people who are working hard to manage geographically stretched supply chains and need to have engi- neers communicate with fabricators and buyers to ensure PCB materials are correctly specified. Even brokers who historically have been out- right commercial operations are now investing in tools for PCB stackup communication. Some leading brokers have done this for several years, but the need is increasingly becoming main- stream. My last prediction for the year is that we will see a continuation of the exciting developments in health enhancement and the ability to im- prove our quality of life. The ability to directly control prosthetic limbs through under-skin im- plants would have seemed the work of science fiction only a couple of decades ago. Best wishes for a healthy and successful 2015. PCBDESIgN THE ROAD AHEAD: 2015 AND BEYOND continues the pulse Whilst looking ahead from a signal integrity perspective, just as in other areas, there seems to be a desire to model more and measure less. " "

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