pcb manufacturing and assembly pcb design
|Material||Laminate material||FR4, Alu, CEM3,Taconic,Rogers|
|Board cutting||Number of layers||1-58|
Min.Thickness for inner layers
(Cu thickness are excluded)
|Bow and twist||<7/1000|
|Copper weight||outer Cu weight||0.5-4 oz|
|inner Cu weight||0.5-3 oz|
|PTH hole tolerance||±0.002''(0.005mm)|
|NPTH Hole tolerance||±0.002''(0.005mm)|
|Plating||Min hole size||0.0008''（0.02mm）|
|Aspect ratio||20(5 :1)|
|Min solder mask clearance||0.003''(0.07mm)|
|E-test||Flying probe tester||Y|
|Impedance tester||Tektronix TDS8200|
|Surface finish||HASL,ENIG,immersion silver，immersion tin, OSP....|
The substrate of the PCB is generally glass fiber. In most cases, the fiberglass substrate of a PCB is generally referred to as the "FR4" material. The solid material "FR4" gives the hardness and thickness of the PCB. In addition to the FR4 substrate, there are flexible circuit boards produced on flexible high-temperature plastics (polyimide or the like) and the like.
Printed boards have evolved from single layers to double-sided, multi-layer and flexible, and still maintain their respective trends. Due to the continuous development of high precision, high density and high reliability, the volume is reduced, the cost is reduced, and the performance is improved, so that the printed board still maintains a strong vitality in the development of electronic equipment in the future.
Factory production of printed circuit boards requires a cumbersome process. In the production process, each technology has a clear method of operation. In addition to making the film, hole metallization and pattern plating etching are the key to production. The original method of making the printed circuit board: For the printed circuit board, the method must meet the quality requirements of the 1:1 original film, and also the original film should be refurbished to produce the film, the original film has two sources. One is to make a photographic base map, and the original negative film is obtained after photographing. One is to directly draw the original negative film by computer aided system and photoplotter, PCB printing and etching and process: resist pattern or electroplating mask pattern There are two general methods: screen printing and photo-drying. The screen printing method is generally used for single-sided or double-sided PCB production with large batch size and low single precision, which is convenient for automation. The photosensitive dry film method is mainly to improve production efficiency, simplify the process, and improve the quality of the board.