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14 The PCB Design Magazine • January 2017 ________________ d ________________ Mark Thompson: It's All about Communication During DesignCon, we talked with colum- nist Mark Thompson about why communica- tion is paramount when designing and proto- typing boards. Thompson also explained how designers can avoid making common mistakes that can set back an entire project. By Barry Matties and Andy Shaughnessy. ________________ e ________________ Trouble in Your Tank: Building Reliability into the PCB, Part 2 Many engineers have been in this situation: Process audits are completed. Personnel who have direct influence are properly trained. Ana- lytical controls are in place. Great! Yet there are boards that are not meeting specification (IPC 6010 Series, IPC 600, IPC 610). And now the team has to deal with the rejects and provide corrective actions. By Michael Carano. ________________ f ________________ Against the Density Wall: Landless Vias Might be the Answer I saw my first landless via multilayer while visiting NEC at Toyama, Japan in 1985. They were an enormous automated facility making Japanese telecom and mainframe computer boards, kind of like IBM and Western Electric rolled into one. NEC was using the liquid elec- trophoretic, positive-acting photoresist pro- cess with panel-plating. I wouldn't see anoth- er landless via multilayer until our Japanese partner, OKI, introduced it to us in 1988. By Happy Holden. ________________ g ________________ From the CAM Shop: Tight Tolerance Design Tips After you finish your design, it winds up in the hands of people like Mark Thompson, the man who runs the CAM department at Pro- totron Circuits in Redmond, Washington. For this issue, we asked Mark to discuss the today's tight tolerances, some of the problems they can cause PCB designers, and what designers can do when dealing with shrinking features. By Andy Shaughnessy. ________________ h ________________ Designers Notebook: Flex and Rigid-Flex Circuit Design Principles, Part 1 Flex circuits have an advantage over hard- wire interface because they fit only one way, eliminating wire routing errors as well as the time needed for testing and inspection. Further- more, flex circuit conductor patterns will main- tain uniform electrical characteristics, control- ling noise, crosstalk, and impedance. By Vern Solberg. ________________ i ________________ Innovative Use of Vias for Density Improvements The classic way to increase density is to reduce the trace and spacing. But in many high-speed board applications, the copper and dielectric losses from smaller traces, or the in- creased crosstalk from reduced spacings, do not permit this. Four old ideas used in board design and fabrication can offer some insight into how routing density can be increased. By Happy Holden. ________________ j ________________ Designing With Tighter Tolerances David Ledger-Thomas is a PCB design en- gineer with Honeywell Aerospace. He's spent decades designing PCBs for a variety of applica- tions, including defense, aerospace, computers, and high-performance audio. I asked David to share some of his thoughts on designing high- tech boards with increasingly finer spaces, trac- es and pitch. By Andy Shaughnessy. PCBDESIGN A HANDY COMPILATION OF OUR TOP 10 DFM ARTICLES