Printed circuit board manufacturing technology

Printed circuit boards (PCBs) are divided into single-sided, double-sided and multilayer boards. Single-sided boards have only one conductive layer, either on the top or bottom side. Double-sided PCBs have conductive layers on both sides, while multilayer boards also contain conductive layers inside the board. When manufacturing PCBs, the layout of the individual layers is important to maintain proper electrical conductivity.

PCBs can be manufactured either by wet etching or dry milling. Both methods are commonly used when manufacturing PCBs, depending on the required quantity, technology and production costs.

General procedure for manufacturing PCBs by wet process

The standard procedure for manufacturing PCBs by etching or wet processing includes:

• Data processing.
• Production of film matrices.
• Preparation of the production panel.
• Cutting, drilling holes and punching the drilled holes.
• A conductive pattern is transferred from the film matrix onto the board, then galvanically strengthened and covered with a tin resist.
• The copper foil is etched and the remaining tin resist is removed.
• A solder mask is applied.
• A service print is added and the surface is finished, for example, with a tin solution.
• The board is then machined by milling and grooving.
• The PCB is metallographically cut.
• The final step is optical and electrical testing.

A much faster method of manufacturing PCBs is milling, also known as dry manufacturing. This process does not require etching and therefore produces no chemical waste from the etching process. On the other hand, its capacity is not suitable for large-volume orders. For this type of production, the price per piece can increase considerably.

Technological procedure for dry manufacturing PCBs

• Using design applications, the input data is processed and a production file is created for drilling holes and milling insulation lines around the conductive surfaces.
• The copper material is gradually removed from the board using special engraving tools, milling cutters and drills with diameters ranging from 0.1 mm to 3.0 mm.
• The type of working tool is important. The tool can have a straight end (End Mill) or a conical end (Cutter). A camera is used to accurately position the board. On a finished PCB, the camera can also be used for control measurements of objects, line widths and hole diameters.
• The next step is to apply a solder mask.
• The board can then be finished with chemical tin.
• Finally, optical and electrical testing is required.

During dry PCB manufacturing, drills and milling cutters wear relatively quickly. Manufacturers usually specify their lifetime in metres, but the actual wear rate depends on the material being processed. Generally, a tool lifetime of around two weeks is expected.

It doesn’t end with manufacturing PCBs

The manufacturing PCBs process does not end when the board leaves the production line. Most manufacturers are aware that moisture, static electricity and thermal shock can cause irreversible damage and even lead to PCB failure. Mechanical damage can also occur during handling and transportation.

Therefore, packaging is just as important as high-quality manufacturing PCBs. Proper packaging protects the PCB during transport and in humid environments.

Manufacturing quality

When manufacturing PCBs, it is very important to pay attention to the quality of every stage of production. In addition to following the correct production technology, manufacturers must maintain optimum humidity levels. Proper humidity helps improve production quality and minimize rejects. Excessive dryness is also undesirable, as a dry environment increases dust levels, which can negatively affect production.

At the same time, not every PCB is suited to every application. Different applications require different PCB surface finishes. The PCB surface can be treated with tin, immersion silver, nickel, gold or other finishes. Each surface treatment gives the PCB different properties and determines its suitability for specific applications.