24.1 INTRODUCTION

The purpose of through-hole drilling printed circuit boards is twofold: (1) to produce an opening through the board that will permit a subsequent process to form an electrical connection between top, bottom, and internal conductor pathways, and (2) to permit through-the-board component mounting with structural integrity and precision of location.

The quality of a hole drilled through a printed circuit board is measured by its ability to interface with the following processes: plating, soldering, and forming a highly reliable, non-degrading electrical and mechanical connection.

As with any process, the elements of the drilling process are:

• Materials

• Machines

• Methods

• Workers

When workers are properly trained and educated so that they possess a sound understanding of the other three elements, it is possible to drill holes meeting the aforementioned requirements with high productivity, consistency, and yield.

The goals of this chapter are as follows:

• Understanding the drilling process thoroughly

• Recognizing what might go wrong

• Locating where problems could occur

• Detecting whether problems do occur

• Finding root causes of problems

• Correcting undesirable conditions

• Striving for zero discrepancies

• Making improvement a team effort

24.2 MATERIALS

Materials that affect the drilling process are as follows and as shown in the fishbone diagram of Fig. 24.1.

FIGURE 24.1: Materials used in the drilling process, with major variables and special considerations identified.

• Laminate material

• Drill bits

• Drill bit rings