1、 Judge appearance with professional tools.

a. The size characteristics of the circuit board include the size and thickness of the printed circuit board, the aperture and the figure accuracy, the wire width and spacing, the coincidence degree and the ring width.

b. Look at the ink color.

The outer layer of PCB circuit board is covered with ink, and ink can play the role of copper line insulation and oxidation prevention. If the color of the board is not bright enough, it indicates that the use of ink by the manufacturer is in the act of stealing work and reducing materials, which will affect the quality of the board.

c. See the welding spot of the welding pad

Modern electronic technology is becoming smaller and more refined. The circuit board is becoming more and more dense, high frequency and high-speed development, and HDI circuit board is also popular. Therefore, the line width distance on the board is smaller and denser.

This requires the use of professional tools and equipment to check whether the line is open circuit, short circuit. Whether the coating of the surface resistance welding has defects such as alignment inaccuracy, blister, bubble, delamination, adhesion, trauma and thickness deviation.

d. Look at surface defects

Check whether the PCB surface has defects such as burr, notch, scratch, groove, fiber scratch, exposed fabric and cavity;

e. Defects under the surface of the circuit board: foreign impurities, white spots / microcracks, delamination, pink ring and lamination cavity;

f. Wire defects: decrease of adhesion, decrease of wire width and thickness due to notch, target, scratch, surface coating or coating defect;

g. Characteristics of holes: pore size, inaccuracy in alignment, foreign impurities and defects of coating or coating;

h. Abnormal identification: including the position, identification, size, readability and accuracy of various electronic components;

2、 Judging from the quality specification requirements of PCB itself.

a. The circuit board shall meet the requirements of electrical testing after SMT patch installation.

b. After the actual machine test, the Board shall not have abnormal heating, open circuit, and short circuit;

c. Under the reasonable use environment of the machine, the copper sheet of circuit board cannot be layered and detached from the substrate;

d. The copper conductor surface of the Board shall not be easily oxidized.

e. There is no additional electromagnetic radiation phenomenon;

f. PCB circuit board appearance is free of deformation, and the hole position and line deformation of PCB shall be within the reasonable range allowed.

g. The Board shall be capable of high temperature, high humidity and special environment resistance.

Finally, what small editors want to emphasize is that we should find a strong PCB Express board factory for proofing, customization and board making of PCB. Only powerful factories like xiangdafeng can have high-end precision PCB production and testing equipment and perfect product quality control system, so as to strive to achieve the best quality of boards.