cheap 4 layer pcb is a very important electronic component. It can be said that it is the support of electronic components and the carrier of electrical interconnection of electronic components. The following introduces the manufacturing process of cheap 4 layer pcb.
1. Material Cutting
Cut out the size that is convenient for processing from the whole large material of CCL with a certain thickness and copper foil thickness.
Drill conductive holes or plug-in holes on the board according to the computer drilling program.
3. Immersion copper
A thin layer of chemical copper is deposited in the drilled hole, the purpose is to deposit a layer of copper on the non-conductive epoxy glass cloth substrate (or other substrate) by chemical method, so as to facilitate the subsequent electroplating and conduction to form a circuit.
4. Full board copper plating
Mainly to thicken and protect the thin layer of chemical copper to prevent it from oxidizing in the air, forming holes without copper or holes.
5. Line (graphic transfer)
Paste dry film on the board or silk screen with anti-plating ink, after exposure and development, the circuit pattern is made.
6. Graphic electroplating
The circuit is thickened and copper-plated on the board with the patterned circuit, so that the copper thickness in the hole and the circuit reaches a certain thickness, and a certain current can be loaded.
Remove the graphic ink or dry film, and etch away the excess copper foil to obtain a conductive circuit pattern.
8. Removal of tin
Remove the tin layer on the formed pattern to expose the desired circuit.
9. Screen printing solder mask ink or paste solder mask dry film
A layer of solder mask ink is printed on the board, or a layer of solder mask dry film is pasted. After exposure and development, a solder mask pattern is formed. The main purpose is to prevent short circuits between lines during soldering.
10. Immersion Gold / tin spray
Do immersion gold on the board or spray a layer of tin where it needs to be soldered, which is convenient for soldering and also prevents the copper surface from oxidizing there.
Some iconic characters are printed on the board, which is mainly convenient for customers to install components.
According to customer requirements, the shape of the board is processed.
13. Electrical measurement
Detect whether there is an open or short circuit in the PCB by means of a closed loop.
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