PCB007 Magazine

PCB-Apr2014

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74 The PCB Magazine • April 2014 by Michael Carano omg electronic cHemicals llc PTH Drilling Revisited: Fundamentals, Part 1 c o l u m n trouble iN your taNk Anyone involved in coaching athletes preaches fundamentals. That means under- standing what is at stake and relentlessly ex- ecuting the basic fundamentals of the craft. Drilling circuit boards is no exception. The ba- sic fundamentals of PTH drilling revolve around several key factors: (1) speeds and feeds—drill in-feed rate and spindle speed of the drill bit; (2) surface feet per minute and (3) the material to be drilled. Understanding and applying these first few critical factors will influence the over- all quality of the drilled, plated through-hole, and eliminate issues such as rough hole-walls, excessive nailheading and resin smear. In a fu- ture column, additional drill fundamentals will be explored. Regardless of whether you are playing a football game or manufacturing a printed cir- cuit board, it is all about fundamentals. Un- derstand what needs to be accomplished and how to get there. Success, however it is defined, should not be difficult to achieve. In this edi- tion of Trouble in Your Tank, I will present some of what I consider the key fundamental under- standings required if one is to drill a quality plated through-hole. Basic Fundamentals The goal is quite simple. You want to build as much reliability into the PTH as possible. Of course, there are numerous factors and process steps involved in manufacturing high-quality, highly reliable PCBs. And yes, drilling is just one of those processes. But the old adage ap- plies here: Garbage in, garbage out. A poor quality drilled via will only exacerbate addi- tional problems downstream in the fabrication process. So it is first and foremost about funda- men tals. In my travels working with PCB and assembly companies on a global basis, I am of- ten struck by the lack of understanding with respect to the basic fundamentals of drilling a plated through-hole. One would think that common sense would prevail, that does not always happen. Suffice to say that one should always consult the drill supplier with help in setting up the proper parameters. This will de - pend on hole diameters, board thickness, resin

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