Circuit board proofing (PCB proofing) refers to the trial production of printed circuit boards before mass production. It is mainly used for electronic engineers to design circuits and complete the drawing of PCBs, and then conduct small batch trial production to circuit board factories, that is, Proofing for circuit boards (PCB proofing).
Circuit board proofing factory production process
1. contact the manufacturer
First of all, you need to tell the manufacturer the documents, process requirements, and quantity.
2. cutting
Purpose: According to the requirements of engineering data MI, cut the large sheets that meet the requirements into small pieces to produce panels. Small sheets according to customer requirements. Process: large sheet → cut sheet according to Ml requirements → copper sheet → beer fillet \ edge grinding → output sheet
3. Drilling
Purpose: According to the engineering data, drill the desired hole diameter at the corresponding position on the sheet that meets the required size. Process: Stacking pins→upper board→drilling→lower board→inspect\repair
4. immersion copper
Purpose: Immersion copper is to deposit a thin layer of copper on the wall of the insulating hole by chemical method.
Process: coarse grinding→hanging plate→immersed copper automatic line→lower plate→immersing in 1% dilute H2SO4→thickened copper
5. Graphic transfer
Purpose: Graphic transfer is to transfer the image on the production film to the board
Process: (blue oil process): Grinding board→printing the first side→drying→printing the second side→drying→exposure one→photographic→checking; (dry film process): hemp board→pressing film→standstill→ Alignment→exposure→rest→develop→check
6. Graphic plating
Purpose: Pattern electroplating is to electroplate a copper layer with a required thickness and a gold-nickel or tin layer with a required thickness on the exposed copper skin of the circuit pattern or on the hole wall.
Process: upper plate → degreasing → water washing twice → micro-etching → water washing → pickling → copper plating → water washing → pickling → tin plating → water washing → lower plate
7. Withdrawing the film
Purpose: To remove the anti-plating coating layer with NaOH solution to expose the non-line copper layer.
Process: water film: insert frame → soak in alkali → rinse → scrub → pass machine; dry film: put board → pass machine
8. Etching
Purpose: Etching is to use chemical reaction method to corrode the copper layer of non-circuit parts.
9. green oil
Purpose: The green oil is to transfer the pattern of the green oil film to the board to protect the circuit and prevent tin on the circuit when welding parts.
Process: Grinding plate→printing photosensitive green oil→copper plate→exposure→developing; grinding plate→printing the first side→baking plate→printing the second side→baking plate
10. characters
Purpose: Characters are provided as an easy-to-recognize mark
Process: After finishing copper with green oil → cooling and standing → screen adjustment → printing characters → final copper
11. Gilding
Finger Purpose: Plating a layer of nickel/gold layer of required thickness on the plug finger to make it more hard and wear-resistant. Copper plating→water washing→nickel plating→water washing→gold plating.
Tin plate?: (a parallel process) Purpose: HASL is to spray a layer of lead and tin on the exposed copper surface that is not covered with solder resist oil to protect the copper surface from corrosion and oxidation, so as to ensure good soldering performance . Process: micro-etching → air drying → preheating → rosin coating → solder coating → hot air leveling → air cooling → washing and air drying
12. Forming
Purpose: Through mold stamping or CNC machine tools to produce the shape required by customers, the method of organic cutting, beer board, hand cutting, and hand cutting. Explanation: The accuracy of data gong machine board and beer board is higher, followed by hand gong, and hand cutting board can only make some simple shapes.
13. Test
Purpose: Through 100% electronic testing, detect open circuit, short circuit and other defects that affect functionality that are not easy to be found visually.
Process: upper mold → board placement → test → qualified → FQC visual inspection → unqualified → repair → return test → OK → REJ → scrap
14. Final inspection
Purpose: Through 100% visual inspection of board appearance defects, and repair minor defects, to avoid outflow of problematic and defective boards.
Specific workflow: Incoming material→Checking data→Visual inspection→Qualified→FQA spot check→Qualified→Packing→Unqualified→Process→Check OK.
circuit board composition
The circuit board is mainly composed of pads, vias, mounting holes, wires, components, connectors, filling, electrical boundary circuit board industrial area, etc. The main functions of each component are as follows:
Pad: A metal hole used to solder component leads.
Vias: There are metal vias and non-metal vias, among which metal vias are used to connect component pins between layers.
Mounting holes: used to fix the circuit board.
Wire: An electrical network copper film used to connect component pins.
Connector: A component used for connection between circuit boards.
Filling: Copper cladding for ground network, which can effectively reduce impedance.
Electrical Boundary: Used to determine the size of the board, all components on the board must not exceed this boundary.
