The Making of Printed Circuit Boards

Printed circuit boards, also referred to as PCBs, are a self-contained module comprised of interconnected electronic components. Formed by a very thin layer of conducting material that is printed onto the surface of an insulating board or substrate, these boards are commonly used for multiple purposes, including radios, computer systems, radars, beepers, pagers, and so on.

To ensure that the fingers on one or more edges are perfect, experts make each board in a precise manner. Depending on the exact design, the boards perform just one function, or can perform many functions.

Perfected Manufacturing

Due to the sensitive nature of printed circuit boards, these boards are manufactured in sterile environments free from contaminants. While processes vary somewhat, making two-sided printed circuit boards typically follows the outlined procedure

  • Substrate—The substrate process starts with aroll of woven glass fiberimpregnated with epoxy resin, which is sprayed on or dipped according to the thickness of the finished product. The substrate then passes through a special oven to be semi-cured, followed by cutting into large-size panels that are stacked in layers with alternating layers of copper foil that have an adhesive backing. The stacks go into a press, reaching temperatures of 340 degrees Fahrenheit and pressures up to 1,500 PSI for at least one hour to cure the resin and bond the copper foil.
  • Holes—Once they’re done, several panels large enough to make printed circuit boards are stacked and pinned together to prevent movement. Experts place these panels in a CNC machine for drilling holes based on the desired pattern. After the holes are deburred, the inside surface provides a conductive circuit from one side to the other with the copper foil backing. Non-conductive holes are plugged to prevent plating.
  • Pattern—Experts then use either a subtractive or addictive process for plating the copper to the substrate’s surface, according to preferred pattern. After plating the entire substrate surface, the pattern is etched away.
  • Final Steps—The contact fingers are attached, tin-lead coating fused, panels sealed, stenciled, and cut, and all components mounted to the printed circuit boards. From there, printed circuit boards get packaged and run through a final quality control check.