|
Printed Circuit Board (PCB) is also known as Printed wiring board. A PCB is basically used for two purposes, i.e. to electrically connect various components of a circuit, as well as mechanically support them, and to mount the components in an electrical device. PCB uses signal traces that are engraved from sheets of copper and other conductive paths on a substrate. PCB manufacturing process starts off with the basic materials to be used. A PCB circuit board is initially a thin, fiber glass epoxy laminate, copper laminates or foil or a non conducting sheet. PCB circuit boards are extremely small in size. Thus identical circuits are printed on a larger panel to make the handling process of PCBs easier. This process is called Panelization. The patterning on a PCB is done by either of two methods, which depends on the number of PCB boards that are to be produced. The method most commonly used is the Subtractive method, in which boards already applied copper layers are purchased. The extra copper is then removed from these boards leaving the copper traces that are desired. The other method, which is an additive method, uses a bare substrate, electroplating the copper onto it. The next step is of Chemical etching. Ether ferric chloride or ammonium per sulfate is used for this part of the process. There are different techniques of etching, depending upon the quantity produced and effectiveness of the methods being used. i. Immersion etching ii. Bubble etching iii. Splash etching iv. Spray etching The combined materials are then laminated by placing them in a press, and pressure is applied. Heat is then added on, for a given time period. The output of this process is an inseparable product. Holes are then drilled in the PCBs using drills having small diameter. The PCB circuit board are then plated with solder, tin or gold. They are again etched to ensure traces are there on the layers. In the end the PCB is coated with solder mask, and anti-corrosion coating The PCB circuit boards are then tested by different methods to make sure that each circuit connection is verified as correct. The different techniques used for testing are bare-board test, a bed of nails tester, flying-grid testers, flying probe and industrial CT scanning,
Related Articles -
Printed, Circuit, Board,
| 
