PCB Fabrication

 
The printed circuit board or PCB is one of the foremost concepts in electronics. In fact, it’s so fundamental that people often forget to explain what it is. Also known as a printed wiring board, PCB is a thin board that physically supports and wires socketed and surface-mounted components in most electronics. Made out of laminate material such as composite epoxy or fiberglass, quality PCB allows the transfer of signal and power between physical devices.

Used in both desktop and laptop computers, PCBs are the substructure for many internal computer components such as network interface cards, controller cards, expansion cards and video cards. Apart from computers, quality PCB is used in other electronic devices such as cell phones, tablets, digital cameras, radios, and TVs. Therefore, understanding the fabrication process of custom PCB is important. Following are the steps involved in the quality PCB fabrication process.

Photoworks

After the required Gerber data is extracted from the customer’s PCB design, plots are manufactured and photoplots are developed.

Cam-Bearbeitung

Standardization of data records of PCB pool’s various software solutions in Ext. Gerber Format.
Preparation of material
Cutting into size of copper clad panels, a back-up board, and the drill entry material
Drilling and Pinning
Pinning of PCB-pool panel onto the CNC machine after tooling holes and reference are drilled.

CNC drilling

Production of component and through-hole plated drills with the help of CNC drill machines.

Through-hole plating

Electroplating of an electrographic film to the drill cavity wall

Brushing

In order to keep free of dust and grease, PCBs are rigorously cleaned before resist lamination

Resist lamination

Using a photosensitive dry resist, the entire PCB pool is laminated under extreme pressures and temperatures

Resist exposure

Exposure of resist to Ultraviolet light with the help of previously generated photoplots

Resist development

Development of exposed panel in a percent of sodium carbonate solution with the help of cyclic construction

ECC

Copper plating of the photo-resist free pads and tracks to a thickness of approximately 35µm

Resist stripping

Using a 2.5% caustic potash solution, the photo resist is stripped away

Etching

Eliminating any excess copper by spraying the copper film with a coat of ammonia solution

Tin stripping

Using a nitric acid based tin-stripper, the tin is removed

Application of soldermask

In order to protect the copper film from accidental contact with conductive bits, solder, or other metal, a soldermask layer is overlaid onto the copper layer.

Silkscreen

A silkscreen layer is printed on top of the soldermask with the help of direct legend printer. In this procedure, the screen print is sprayed directly onto the custom PCB.

Tempering

For approximately an hour, the soldermask is burned-in at a temperature of 150°C.

Surface finish

Coating of the outer most layer of a printed circuit board (PCB). There are two types of surface finish or coating i.e. metallic and organic.

Routing

Using a CNC routing machine, PCBs are routed from the PCB pool panel in the final stages.

Electrical test

The final step in the custom PCB fabrication process is the electrical test. In this procedure, all PCBs on site are electrically tested.