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8 SMT Magazine • November 2017 by Stephen Las Marias I-CONNECT007 What Matters Most is Communication There is a growing trend towards the use of HDI in electronics manufacturing. A simple reason is that people want greater performance from their electronics, now more than ever. From an electronics design standpoint, greater performance means more switches or transis- tors. More transistors mean more power. Coun- terintuitively, more power requirements of a de- vice means you need to lower the power of the whole system or subassembly. You also need to lower the power because then, you need to deal with thermal management. To lower the power requirement, everything must be reduced. As such, the components keep getting smaller and smaller. Pin pitches are now down to 0.25 mm or around 10 mil. On top of that, the overall density of board assemblies continuously increases in line with the growing demand for more features and functions. Add - ing to that challenge is the shrinking PCB real estate on which to put this increasing number of components. Our recent survey on HDI found that the three key factors driving HDI work are: overall density, fine pitch of components, and the high pin counts of ICs (Chart 1). At present, majority of our surveyed respon - dents say up to 25% of PCBs they work with use HDI technology (Chart 2). In three years, nearly half of the respondents answered that HDI technology will account for at least 50% of their PCB work. This is across a vari- ety of industries, top three of which are consum- er electronics, telecommunications, and automo- tive electronics. In particular, the emergence of 5G and Internet of Things (IoT) are expected to bolster the use of HDI technology due to frequen- cy and signaling requirements (Chart 3). Assemblers have different areas of concern re- garding HDI than fabricators and designers. When it comes down to having vias in the boards, espe- cially vias in pads, issues will arise if the assembly is the not done properly . "When you put a via in a pad, you typically want to fill that via, with ei- ther a non-conductive or conductive epoxy, and use some sort of plating over the barrel of the via so that you get a smooth pad that you are assem- bling the part to without a whole lot of surface de- viation. The flatter the pad, the easier it is to print solder on the board, and to assemble the part," said Garret Maxson of EMS firm ACDi. This month' s issue of SMT Magazine examines the challenges when dealing with HDI from an as - sembly perspective. We start with a roundtable be- tween HDI experts Steve Bird of Finisar, Tony Tor- res of APCT, and technologists from EMS firm MC Assembly, including Vince Burns, Steve Jervey, Mike Smyth, and Paul Petty. The discussion cov- ers the latest technology developments, manufac- turing challenges, and HDI strategies, from the de- sign, fabrication, and assembly perspectives. What we found out is that, while there may be new tech- E DITOR'S NOTE 0 10 20 30 40 50 60 70 80 What market trends are driving your HDI work? Q: Overall Fine pitch High pin Signal Electrical Cost Other 79% 63% 40% 35% 21% 19% density count integrity engineering requirements Chart 1. Source: I-Connect007 Research

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