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In simple terms, a circuit board is but a composition of things designed to be connected and not. The number of layers and number of connections make no real difference as the geometry shapes the landscape. The via is but one tool that helps in building the wonder that is a printed circuit board, and in this column, we’ll discuss the via in relation to the variety of types available for use as well as some of the testing that can be performed on them to ensure their reliability.
A small—sometimes very small—yet important part of the circuit board landscape, the via, by definition, is simply the means by which layers of the board can be interconnected. What differentiates the via from a plated through-hole is simply the fact that nothing (i.e., a component lead) will get inserted and possibly soldered into the structure. Further, vias don’t have to extend from one side of the board to the other, although they certainly can as a through via.
Blind vias start at the surface on one side of the board but don’t extend to the other side, while buried vias (Figure 1) are completely encapsulated within the board with no end extending to either surface of the board.
To read this entire article, which appeared in the November 2016 issue of The PCB Magazine, click here.
Pete Starkey, I-Connect007
Örebro, Sweden on June 15 brought a bright and early start to Day 2 of the EIPC Summer Conference for those who had enjoyed the previous evening’s networking dinner, but had resisted the temptation to over-indulge or to carry on their long-awaited catch-up conversations with old friends into the small hours. All but a few were in their seats for 9 a.m., awake and attentive for Session 4 of the conference, on the theme of new process technologies, moderated by Martyn Gaudion, CEO of Polar Instruments.
Pete Starkey, I-Connect007
Bringing a specialised technical area into sharp focus, this month’s topic was “5G and the understanding of loss minimisation at the PCB level,” with papers on dielectric material, copper foil, and modelling solutions. The webinar was moderated by EIPC board member Paul Waldner managing director of Multiline International Europa, who admitted that he had managed to get a haircut especially for the occasion!
A circuit board is made of copper. Usually, final finishes are applied after the solder mask process. In some cases, for special applications, the final finish may be applied before solder mask. In this case, we have solder mask on ENIG or galvanic nickel-gold. It is also possible to have tin or tin-lead under solder mask; this was an old technology that no longer plays a role today.