The process of PCB (Printed Circuit Board) becoming PCBA (Printed Circuit Board Assembly) mainly includes the following key steps:

1. SMT patch (Surface Mount Technology)

Solder paste printing: Use a steel mesh to print solder paste evenly on the PCB pad.

Patch: Use a high-speed patch machine to accurately mount electronic components to the corresponding 

pad position on the PCB.

Reflow soldering: Use a reflow oven to melt and cool the solder paste to form a reliable solder joint.

AOI inspection: Use automatic optical inspection equipment to check the soldering quality, such as whether 

there are defects (false solder joints, bridging tin, missing parts, etc.).

2. DIP plug-in (Dual In-line Package) [For components that require plug-in]

Plug-in: Manual or automatic plug-in machines insert electronic components with pins (such as capacitors, 

inductors, connectors, etc.) into through holes on the PCB.

Wave soldering: The PCB passes through a molten solder wave to fix the plug-in components.

Trimming and trimming: Trim off excess pins and trim solder joints.

3. Soldering and assembly

Manual soldering: For some special components (such as high-power devices and special interfaces), 

manual soldering is required.

Cleaning: Remove residual flux and impurities during the welding process to improve the reliability of the 

circuit board.

Assembly: Install additional components such as heat sinks, housings, shielding covers, etc.

4. Testing and quality inspection

Functional test (FCT): Check whether the functions of the PCBA are normal, such as voltage, current, 

signal transmission, etc.

ICT test (In-Circuit Test): Check circuit parameters such as resistance, capacitance, inductance, IC pin connection, 

etc. through test points.

Aging test: Test the stability and life of the PCBA under extreme environments such as high temperature and high 

humidity.

5. Packaging and shipment

Protection treatment: Spray three-proof paint (moisture-proof, salt spray-proof, anti-static), etc. to ensure that the

 PCBA is not affected by the environment during transportation and use.

Packaging: Use anti-static packaging materials to ensure that the PCBA is not damaged during transportation.

Delivery: Deliver the finished PCBA to the customer or use it for whole machine assembly.

Summary

PCB is just a bare board, while PCBA is a complete circuit board after a series of processes such as component 

mounting, welding, and testing. PCBA can be directly used in various electronic devices, such as smart home,

 automotive electronics, medical equipment, etc.