How to Make Printed Circuit Boards (PCBs)?
PCB was born in the 1940s and 1950s and developed in the 1980s and 1990s. With the advancement of semiconductor technology and computer technology, printed circuit boards are developing towards high density, thin wires, and more layers. Its design technology has also developed from the initial manual drawing to computer-aided design (CAD) and electronic design automation (EDA).
PCB Classification
-Classified by layer
Classification according to the number of circuit layers: divided into single-sided, double-sided and multi-layer boards. Common multi-layer boards are generally 4-layer boards or 6-layer boards, and complex multi-layer boards can reach dozens of layers.
-Classified by soft and hard
Divided into rigid circuit boards and flexible circuit boards, flexible and rigid boards. The common thickness of rigid PCB is 0.2mm, 0.4mm, 0.6mm, 0.8mm, 1.0mm, 1.2mm, 1.6mm, 2.0mm, etc. The common thickness of flexible PCB is 0.2mm
PCB Production Process
1. Cutting
Purpose: According to the requirements of the engineering data MI, on the large sheets that meet the requirements, cut into small pieces for production. Small pieces that meet the customer's requirements.
Process: large sheet → cutting board according to MI requirements → curium board → fillet edging → plate out
2. Drilling
Purpose: According to the engineering data (customer data), drill the required hole in the corresponding position on the sheet that meets the required size.
Process: stacked board pin → upper board → drilling → lower board → inspection and repair
3. PTH
Purpose: Immersion copper is to deposit a thin layer of copper on the wall of the insulating hole using a chemical method.
Process: rough grinding → hanging board → automatic copper sinking line → lower board → dip 1% dilute H2SO4 → thickened copper
Purpose: Graphic transfer is to transfer the image on the production film to the board
Process: (blue oil process): grinding plate → printing the first side → drying → printing the second side → drying → exploding → shadowing → inspection; (dry film process): hemp board → laminating → standing → right Position→Exposure→Standing→Development→Check
5. Graphic Plating
Purpose: Pattern electroplating is to electroplate a copper layer with the required thickness and a gold-nickel or tin layer with the required thickness on the bare copper skin or hole wall of the circuit pattern.
Process: upper board → degreasing → second washing with water → micro-etching → washing → pickling → copper plating → washing → pickling → tin plating → washing → lower board
6. Remove the Film
Purpose: Use NaOH solution to remove the anti-plating coating film to expose the non-circuit copper layer.
Process: water film: insert rack → soak alkali → rinse → scrub → pass machine; dry film: release board → pass machine
7. Etching
Purpose: Etching is to use chemical reaction to corrode the copper layer of non-circuit parts.
8. Green Oil
Purpose: Green oil is to transfer the graphics of the green oil film to the board to protect the circuit and prevent the tin on the circuit when welding parts
Process: grinding plate → printing photosensitive green oil → curium plate → exposure → photofinishing; grinding plate → printing the first side → drying plate → printing the second side → drying plate
9. Characters
Purpose: Characters are provided as a mark for easy identification
Process: After the green oil finishes → cool and stand → adjust the screen → print characters → back
10. Gold-Plated Fingers
Purpose: Plating a nickel-gold layer with the required thickness on the finger of the plug to make it more hard and wear-resistant
Process: upper board → degreasing → washing twice → micro-etching → washing twice → pickling → copper plating → washing → nickel plating → washing → gold plating
11. Tin Plate
Purpose: Tin spraying is to spray a layer of lead tin on the exposed copper surface that is not covered with solder mask to protect the copper surface from corrosion and oxidation to ensure good soldering performance.
Process: micro-erosion → air drying → preheating → rosin coating → solder coating → hot air leveling → air cooling → washing and air drying
12. Forming
Purpose: through die stamping or CNC routing machine to produce the shape required by the customer.
13. Test
Purpose: To pass electronic 100% testing to detect defects that affect functionality such as open circuits and short circuits that are not easy to find visually.
Process: upper mold → release board → test → qualified → FQC visual inspection → unqualified → repair → return test → OK → REJ → scrap
14. Final Inspection
Purpose: To pass 100% visual inspection of the board's appearance defects and repair minor defects to avoid problems and defective boards from flowing out.
Specific work flow: incoming materials → view information → visual inspection → qualified → FQA spot check → qualified → packaging → unqualified → processing → inspection OK
