With the increasing complexity of electronic equipment, more and more parts are needed, and the lines and parts on PCB are more and more dense. A bare board (with no parts on it) is also often called a "printed circuit board (PWB)". The substrate of the board itself is made of insulating and heat-insulating materials that are not easy to bend. The fine wiring material visible on the surface is copper foil. Originally, the whole board was covered with copper foil, but a part of it was etched away in the manufacturing process, and the rest became fine wiring in a mesh. These wires, called conductor patterns or wiring, are used to provide circuit connections for components on the PCB.
Usually the color of PCB is green or brown, which is the color of solder mask. It is an insulating protective layer, which can protect copper wire and prevent parts from being welded to incorrect places. The screen will be printed on the solder mask. Usually words and symbols (mostly white) are printed on it, indicating the position of each part on the chessboard. Screen printing surface is also called legend.
The history of PCB
The inventor of the printed circuit board is an Austrian named Paul isler, who adopted the printed circuit board in a radio device in 1936. In 1943, Americans have widely used this technology in military radios. 1948, the United States officially recognized the invention for commercial use. Since the mid-1950s, printed circuit board technology has been widely used.
Before the appearance of printed circuit board, the interconnection between electronic components was realized by direct connection of wires. Now, the circuit bread board only exists as an effective experimental tool; Printed circuit boards have occupied an absolute dominant position in the electronic industry.