PCB circuit board production process in the factory

Printed circuit board is a key component in electronic assembly. It is equipped with other electronic components and connected circuit, in order to provide a stable circuit working environment.


Processing flow


[inner line] copper foil substrate cut into the size of the size suitable for processing. The substrate film usually need to use the brush before grinding, micro etching methods such as surface roughening of copper foil as appropriate, then the temperature and pressure of the dry film photoresist attached on the seal. The paste dry film photoresist substrate into the ultraviolet exposure machine exposure, ultraviolet light resistance in negative transmission region will produce polymerization reaction, and the negative image line shifted to the surface of dry film photoresist. After removing the protective film on the surface of the membrane, the sodium carbonate aqueous solution is used to remove the area which is not covered by the light on the surface of the membrane, and then the exposed copper foil is removed by the hydrogen peroxide mixed solution to form a circuit. Then the light oxidation of sodium aqueous solution of dry film photoresist retire after winning merit in addition to washing.


After the completion of the inner circuit board must be glass fiber resin film and the outer circuit copper foil adhesive. Before pressing, the inner plate needs to be treated by black (oxygen), so as to increase the insulation of the copper surface, and to make the inner surface of the copper wire rough so as to produce good adhesion with the film. The first circuit board inner layer superimposed on six layers above the line with the paired riveting riveting machine. And then put it into a flat plate in the mirror between the steel plate, into the vacuum press in the appropriate temperature and pressure to make the film hardening and bonding.


The circuit board uses the CNC drilling machine to drill through the through hole of the interlayer circuit and the fixing hole of the welding part. When drilling through holes drilled in the previous target to fix the circuit board on the drilling machine platform with a pin, and the formation of the lower plate and the upper cover plate to reduce the occurrence of drilling well.

When the interlayer conducting hole is formed, the metal copper layer is needed to be arranged on the interlayer conducting hole, so as to realize the communication between the layers. In severe and high pressure washing brush grinding way to clean dust and lint holes on the hole in the wall clean soak adhered tin


[a copper] palladium colloid layer, and then reduced to palladium metal. The circuit board is immersed in the chemical copper solution, and the copper ion in the solution is reduced and deposited on the hole wall by the catalysis of palladium metal to form a through hole circuit. The copper layer in the through hole is thickened to resist the thickness of the subsequent processing and the impact of the environment in the way of the copper plating bath.


[two] in the outer layer of copper production line image transfer as inner line, but in the etching is divided into positive and negative two production modes. The negative mode of production as inner line production, after developing direct copper etching, the film is complete. The positive mode of production is in the developer after plating two copper and tin lead, copper corrosion to the membrane after removal by alkaline ammonia and copper chloride mixed solution will be exposed, forming line. Then the tin lead stripping liquid tin lead layer stripping retire after winning merit.


[solder printing ink printing] earlier than the green paint is the use of screen printing after direct thermal drying (or UV irradiation) to make the film hardening mode of production. But because of the resulting green paint penetrated into the copper surface contact line terminal on the printing and hardening process usually produce welding parts and problems in use, now in addition to simple straightforward use of printed circuit board, which can be produced by light green paint.


The anti welding green paint covers most of the copper surface of the circuit, and only shows the terminal contact for the welding of the parts, the electrical test and the circuit board insertion. The endpoint needs to be additionally provided with a protective layer to prevent the generation of an oxide in the anode (+) in the long-term use, thereby affecting the stability of the circuit and causing safety concerns.


[forming cutting] the circuit board to CNC molding machine (or die punch) cut into the customer needs of the external dimensions. When cutting through the positioning holes previously drilled to fix the circuit board on the bed forming pin. Then the beveling processing to facilitate the use of cutting circuit board is inserted after the finger position.


[board packaging] commonly used packaging PE film packaging shrink film packaging vacuum packaging, etc..


 

(Source: http://www.pcbpartner.cn/News/article/20160613/20160613000000045982.shtml)

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