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Printed Circuit Boards Assembly (PCBA) Process

Nowadays electronic components are becoming an inseparable part of our lives. They are widely applied in many industries, such as consumer electronics, home appliance, automotive, IOT, defense, aerospace, networking, etc. All these products have the essential parts, namely the printed circuit board, known as PCB and electronic components.

The electronic circuit boards are easily recognizable. They are green chips covered in lines and copper parts. There are many circuit board components on the top of the pcb board, and these are the electronic components such as resistors, MCUs, capacitors, etc.

Many visitors are curious about the PCB Assembly process. This page will give a detailed introduction about the printed circuit board assembly process.

The printed circuit board assembly (PCBA) process is divided into six phases including 12 steps:

Phase 1: Solder Paste Stenciling

The first phase of PCB assembly process is applying the solder paste to the printed circuit board, which is for applying the solder paste only to the parts where the electronic components locate on the pcb board. After finishing this process, you will get soldering circuit boards.

Note: All the solder pastes needs to be stored in the refrigerators.

Phase 2: Pick and Place the components

After the circuit board are applied with solder paste, the next step is to place the electronic components on the soldering circuit boards and make sure each components sit at its corresponding place with the right direction. In this process, the machine will pick up all some small components such as resistors and place them on the pcb board. In addition, other machines will pick up the large components such as MCU and place them on the circuit board accordingly.

Phase 3: Reflow Soldering

Although the components are placed on the printed circuit board at its right location, the components are not solidified or fastened on the pcb board. Therefore, the reflow soldering process is required to solidify the components, which is the process of getting the printed circuit boards with components on it going through a reflow oven. This reflow oven has a series of heaters with different temperatures.

Phase 4: Inspection and Quality Control

After the electronic components are soldered or solidified on the printed circuit board during the reflow process, inspection is required to make sure that all the parts are solidified, at the same time, to ensure that all the components are placed in the right locations with right direction. There are several steps adopted for inspection and quality control:

Step 1: Automatic Optical Inspection: we use machine to check the placement and locations of the components
Step 2: Manual Checks: to ensure the soldering quality, the manual checks are required
Step 3: X-ray Inspection: this type of inspection is more complex and accurate, which can identify some potential problems that cannot be found with other methods.

Phase 5: Through-hole Component Insertion

After the electronic components are solidified on the PCB board, some components will be plated through the hole if there are such components requirement for that PCB board.

Normally the soldering process for the through-hole components is different from soldering paste, they need to be done manually and has two steps:
Manual Soldering: The through-hole components will be inserted into the PCB board manually
Wave Soldering: Wave soldering is a manual soldering process. After the through-hole components are inserted into the PCB board in the previous step, these components will be soldered manually.

Phase 6: Final Inspection and Function Test

After the whole process has been finished, a final inspection is required to make sure that all the components are right soldered with the right direction and at the right position. After this, the final step is to test the function of the printed circuit board to make sure that it can function properly before shipment. Allchips has a very strict quality control and inspection system to make sure that we will deliver the high quality products to our customers.

PCB Assembly Process Flow