The term circuit technology usually refers to the various techniques that used in the manufacture of electrical circuits. A large number of devices that are used today make use of printed circuit boards (PCBs). These devices provide a mechanical support for the various components present within the given device and also, the electrical connections between the components.
The electrical connections present on the PCB are made out of copper sheets that are laminated on a non-conducting material. Initially a large copper sheet is laminated on the board and then the sections that are not required are removed. Various techniques are used for removal of unwanted copper. Some of them are:
- Silk Screen Printing: In this technique, an etching resistant ink is applied on those areas that are required and the remaining part is etched off.
- Photoengraving: Here a photo mask of the circuit required is prepared using desired software and then, it is applied onto the blank PCB. After this the portions that are not required are etched off.
- PCB Milling: In this technique, a mechanical milling system that can work on 2 or 3 dimensions is used to remove the copper. The milling system is controlled by software.
In some other techniques only the required copper is added onto the board.
After this process, holes are drilled on the PCB as required. Again this process is controlled by computers in order to attain the necessary accuracy. In some cases, printed circuits are present on both the sides of the board. The two sides of the boards are interconnected by the means of a hale that has copper plating on its surface.
The surfaces of the boards where the components are to be mounted are coated with specialised materials as copper tends to oxidise at a quick rate.
After the completion of etching process, the boards are coated with a layer of tin. This helps in maintaining their solderability even after storing them for a few months. The information about the various components present in a PCB can be printed on its surface by the means of screen printing. New digital techniques have been developed for screen printing that can accurately print bar codes on the surface.
Before the connections are mounted on the board, the every connection present on the board is tested. Various techniques may be used for the same. Specialised tests such as the â€˜Bed of Needles’ test are used in case of PCBs that are mass produced.
After the testing process is completed, the various components are mounted on the PCB. By using some techniques, the pins of the devices are inserted into the holes present on the PCB. This completes the manufacturing process of the PCB then, it needs a safety certification and then, it can be introduced into the market.
There are many examples of PCBs. For example, the mother board present in the computer, the RAM etc. are PCBs. They are also used in various other devices such as remote controls, calculators etc.