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74 The PCB Magazine • July 2016 The PCB industry in Brazil has gone through several changes over the last decade. Our cus- tomers have been demanding better quality and higher-reliability products more than ever before, but few things have changed as much as impedance control. PCBs with impedance control requirements have become the engine of the market, and finding solutions to fit the customer's needs is extremely challenging. Ten years ago, the Brazilian PCB industry was a little vague on this subject, and very few PCB shops were doing impedance testing. About five years ago, with the evolution of the national PCB industry, customers started producing prototypes requiring impedance control and the market started to develop. However, it seemed to me that neither the customers nor the PCB shops really knew what to order and to deliver at that time. There always were differences between the specs for the board, the coupon measured, and the simulation software. As a best practice, many PCB shops used to appeal to a cross-sec- tion analysis to verify the PCB build up. In the end, impedance simulation software was more reliable than the TDR measurements. I remember I felt a bit normal last year when I read the article written by Dan Beaulieu and Bob Tarzwell for The PCB Design Magazine, Con- trolled Impedance: A Real-World Look at the PCB Side. Coupons that don't fit the specs of the customers, cross-section analyses, differences in resin flow during lamination, copper thickness variation, and many other issues described in the article were very similar to the problems we faced daily. Nevertheless, the industry in Brazil has gone further, pressing the suppliers to develop new controls, not yet usual to the national market. The real challenge right now is to measure the impedance on a board, and make these re- sults similar to the coupon results, so that the coupon becomes useful. by Renato Peres CIRCUIBRAS FEATURE COLUMN: MADE IN BRAZIL

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