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PTH Drilling Revisited - Fundamentals, Part 1

Anyone involved in coaching athletes preaches fundamentals. That means understanding what is at stake and relentlessly executing the basic fundamentals of the craft. Drilling circuit boards is no exception. The basic 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 overall quality of the drilled, plated through-hole, and eliminate issues such as rough hole-walls, excessive nailheading and resin smear. In a future column, additional drill fundamentals will be explored.     

Regardless of whether you are playing a football game or manufacturing a printed circuit board, it is all about fundamentals. Understand what needs to be accomplished and how to get there. Success, however it is defined, should not be difficult to achieve. In this edition of Trouble in Your Tank, I will present some of what I consider the key fundamental understandings 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 applies here: Garbage in, garbage out. A poor quality drilled via will only exacerbate additional problems downstream in the fabrication process. So it is first and foremost about fundamentals. In my travels working with PCB and assembly companies on a global basis, I am often 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 depend on hole diameters, board thickness, resin materials and drill machine capabilities.  But there are basic fundamentals that apply. So let’s discuss the basics and illustrate what some of the undesired outcomes are when we do not follow the rules.

Read the full column here.


Editor's Note: This column originally appeared in the April 2014 issue of The PCB Magazine.