In the professional PCB installation, the mechanical fixture fix PCB and welded templates at appropriate positions. Then use a brush to place the tin paste at the expected area with accurate amount. Then, the machine spreads the paste on the template and brushes it evenly to each open area. After removing the template, the welding paste is retained in the expected position.

After brushing the welded paste on the PCB board, the assembly process will be transferred to the picker (PCBA Store SMT machine: yamaha, Panosonic). Put the process. The robot then aligned the PCB on the workbench and began to apply SMT to the PCB surface. These components are placed on the pre -pre -programmed position on the top of the welded paste, which is called SMT.

After the welding balm and surface installation components are placed in place, they need to be kept there. This means that the welding paste needs to be curing and adheres to the component to the board. PCB assembly is achieved by the process of calling “backflow”.

After picking up and placing the process, the PCB board is transferred to the conveyor belt. The conveyor belt passed through a large return furnace, and the flow furnace was a bit like a commercial pizza furnace. The oven consists of a series of heater, which gradually heated the board to the temperature of about 250 degrees Celsius or 480 Hualhi. Its temperature is enough to melt the solder in the tinnum.

After welded, the PCB continued to pass through the oven. It cools and solidifies the melting welded through a series of cooler heater. This will create a permanent solder to connect SMD to PCB.

Once the surface paste component is welded after the return process, the function of the circuit board can be tested. Generally, the movement during the return process will lead to poor or lost connection. Short circuit is also a common side effect of this movement, because components in the wrong position sometimes connect to parts that should not be connected in the circuit.

Inspection method includes: manual examination

Automatic optical test (called AOI)

X -ray inspection (most commonly used for more complex or layered PCB.)

The most important aspect of PCB assembly is testability. The PCB assembly process is seriously dependent on our test level. In the final stage of the assembly process, we will create a test board. The test board allows us to test our electronic components and verify whether they work normally. For example, if we use a microcontroller, we can test whether the micro -controller is correctly received instructions from the computer. We can also use oscilloscope and other tools to test our functions.

According to the type of circuit board in the assembly, the circuit board may include various components other than ordinary SMD. These include plating hole components or PTH components. This requires artificial manual plug -in to complete.

After completing the welding steps of the PCB assembly process, the final inspection will test the function of the PCB.