What is the Assembly Process of Circuit Board?

1. What is circuit board assembly

Circuit board assembly is to process on the empty circuit board, install resistors, capacitors, chips and other components, through SMT patch, DIP plug-in and testing, etc., to form a board with certain functions. The circuit board assembly process is a simple and long process, and the specific steps are as follows.

Ⅱ. The specific steps of circuit board assembly

1. Solder paste printing

Solder paste printing is the basic step of circuit board assembly. Regardless of the type of circuit board, this step remains the same. A steel mesh made of a thin metal plate is placed on the plate. This ensures that the solder paste is only applied to the area where the components are to be installed. After applying the solder paste, remove the stencil from the board.

2. Pick and place component installation

Component installation is a pick and place activity that can be performed manually or mechanically by an automated system (such as pick and place machine for PCB assembly). In the through-hole circuit board assembly, the assembly is performed manually. In surface mount circuit board assembly, this is performed by automated machines. Automatic component mounting provides a fast, accurate and error-free circuit board assembly process.

3. Welding

Solder to connect the components on the circuit board. In the through-hole assembly, wave soldering is performed. In this case, the circuit board on which the components are mounted will move on the hot wave soldering fluid. This will liquefy the solder balls and then cool them at room temperature to solidify the solder paste. However, in the surface mount circuit board assembly, reflow soldering is performed.

4. Check

Perform inspections and quality tests to ensure the functionality of the equipment. It involves three different inspection methods, as described below.

1) Appearance/manual inspection

Manual inspection is only sufficient to check solder connections, this method is only suitable for small batches of circuit boards.

2) Automatic optical inspection (AOI)

The AOI machine has a high-resolution camera that can be aimed at different angles to test the circuit board. This type of inspection is suitable for single or double-sized circuit boards, but not enough for multi-layer complex circuit boards.

3) X-ray inspection

X-ray inspections are performed on complex circuit board designs with multi-layer component mounting. Such complex circuit boards are difficult to inspect optically.

4) Inspection and functional test after assembly

After the assembly is complete, check the circuit board again and test its function. Perform functional tests, such as microsection test, contamination test, and solderability test, to end the circuit board assembly process.

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