At which step in the PCBA process does reflow soldering occur?
20 December 2024
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Reflow soldering is a critical step in the PCB assembly process that is required to ensure that components are securely connected to the PCB. But at which step in the PCBA process does reflow soldering occur?
Overview of the PCBA process
1. Solder paste
Solder paste is applied to the PCB, using a stencil to ensure that the solder paste is deposited only on the pads where the components will be placed.
2. Component placement
Once the solder paste is applied, the components are assembled on the PCB, performed by a high-speed automatic pick-and-place machine.
3. Reflow soldering
After placing the components on the PCB, the PCB enters the reflow soldering process, where the solder paste melts to form a secure connection between the components and the board.
4. Inspection and testing
After reflow soldering, the assembled board is inspected for soldering defects and functional tests are performed to ensure that it works.
5. Through-hole component insertion (if required)
If the board requires through-hole components, these components are inserted and soldered, using wave soldering and manual soldering.
6. Final assembly and quality control
The last step is to assemble other accessories and conduct rigorous testing to verify the functionality of the product.
What happens during reflow soldering?
1. Preheating
The PCB enters the reflow oven and is gradually heated to prevent thermal shock, which can stabilize the temperature of the circuit board and components.
2. Soaking
The temperature rises further, activating the flux in the solder paste. The flux removes oxides from the metal surface and ensures a clean soldering surface.
3. Reflow (peak temperature)
The solder paste reaches its melting point, usually between 220°C and 250°C, depending on the solder material. The molten solder forms a strong bond between the component and the PCB pad.
4. Cooling
The PCB is gradually cooled to solidify the solder joints.
Conclusion
Reflow soldering is the process of PCB assembly after applying solder paste and preventing components.