Printed circuit board manufacturing technology

Printed circuit boards (PCBs) are divided into single-sided, double-sided and multilayer. Single sided boards have only one side conductive either top or bottom. Double-sided PCBs have a conductive layer on the top and bottom side, and multilayer boards contain conductive layers inside the board as well. In a multilayer board, the layout of the boards is important to maintain conductivity.

PCBs can be manufactured either by wet etching or dry milling.

General procedure for the manufacture of PCBs by wet process

The standard procedure for manufacturing a board by etching or wet process is:

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

A much faster way of manufacturing is the milling method, i.e. dry manufacturing. This is without the need for etching and the creation of chemical waste. On the other hand, the capacity cannot cover orders with many pieces. In such production, the price per piece increases considerably.

Technological procedure for dry production of PCBs

• With the help of design applications, the input data is processed and a prescription is created for drilling holes and milling insulation lines around the perimeter of the conductive surfaces.
• Gradually, the copper material is 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 end of the working tool is important, which can be straight (End Mill) or conical (Cutter). There is a camera that is used to aim and position the plate. On the finished plate, the camera can be used to make control measurements of objects, line widths, hole diameters.
• The next step is to apply a non-soldering mask.
• And as a result, the plate can be tinned with chemical tin.
• Finally, optical and electrical testing is required.

With this method, the wear of drills and milling cutters is relatively fast. Manufacturers give their lifetime in metres, but it depends on the material being drilled how quickly wear occurs.  Generally a life of 2 weeks is given.

It doesn't end with production.

In the PCB manufacturing process, most manufacturers realize that moisture in the air, static electricity and thermal shock can cause irreversible damage and even cause the PCB to fail. As well as mechanical damage.

Therefore, packaging is as important as quality manufacturing. 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 each part of the manufacturing process. In addition to adhering to the production technology, it is necessary to ensure optimum humidity percentages. Proper humidity helps to increase the quality of production and minimize rejects. On the other hand, excessive dryness is also not desirable. On the contrary, a dry environment increases dustiness, which also negatively affects production.

At the same time, not every PCB is suited to a particular application. Different applications will allow for different PCB finishes. The PCB surface may not only be surface treated with tin solution, but also with immersion silver, lead or gold, etc. And each surface treatment gives the PCB different properties and uses.  If you want to learn more about the properties of PCB finishes, you have the opportunity in the article How to choose from the widest portfolio of surface finishing.