Product & Technology

The first stage of the PCB assembly process is to check each PCB board is correct and the incoming components are consistent with the BOM to be soldered. The purpose of raw material inspection is to prevent poor quality and delay delivery from defective materials.

1.Raw Material Inspection

Place the thin, stainless steel stencil over the board using a mechanical fixture. Solder paste should be applied evenly to the circuit board in the exact locations needed.

2.Solder Paste Printing

3.Solder Paste Inspection (SPI)

Postprint inspection is essential for quality assurance of deposited solder paste layers and their suitability for the following step-surface mounting of electrical components.  SPI can directly check the quality of solder paste on PCBs, and provide a hint of the types of defects.

4.Pick and Place

SMDs, or surface mount components, should be placed on a prepared PCB by a robotic device. Then, the components need to be soldered onto the circuit board surface.

5.Reflow Soldering

This process ensures that the solder paste solidifies and that components are affixed to the board. Essentially, after pick and place the PCB board is moved to a conveyor belt.  It is here that the board is heated to about 250 degrees Celsius, which melts the solder.  Now it moves to cooler heaters where the solder cools and solidifies.

This now connects the components to the printed circuit board.

6.X-Ray, AOI optical detection

AOI or Automatic Optical Inspection- This is suited for large batches where an AOI machine is used that has cameras at different angles. With different quality solders reflecting light in different ways, it is easy to identify the low-quality solder.

X-Ray inspection- For layered PCBs, this method works well.

7.Through-Hole Component Insertion

Some PCBs require through-hole components as well in conjunction with the common SMD components, through-hole technology used for electronic components that involves the use of leads on the components that are inserted into holes drilled in printed circuit boards and soldered to pads on the opposite side either by manual soldering, wave Soldering or the automated insertion mount machines.

8.Final Inspection and Functional Test

After the soldering step of the PCBA process is finished, a final inspection will test the PCB for its functionality. This test will simulate the normal operation of the PCB, and monitor the electrical characteristics of the PCB when the power supply and analog signal pass through the PCB to judge whether the PCBA is qualified.

PCBA Process Flow