The Soldering Process for PCBA Includes The Following Steps
According to customer Gerber file and BOM list, make process file for SMT production and generate SMT coordinate file.
Inventory all the production materials whether they are ready or not, make the flush set list, and confirm the PMC plan for production.
Perform SMT programming and make the first board for checking to make sure there is no error.
Make laser stencil according to SMT process.
Perform solder paste printing to ensure uniformity, good thickness and consistency after printing.
Through the SMT mounter, mount the components onto the circuit board, and carry out in-line AOI automatic optical inspection if necessary.
Set the perfect reflow oven temperature profile to allow the circuit board to flow through the reflow soldering, the solder paste is transformed from paste and liquid to solid, and good soldering can be realized after cooling.
After the necessary IPQC center inspection.
The DIP plug-in process passes the plug-in material through the board and then flows through the wave solder for soldering.
Necessary post-oven processes such as foot trimming, post-soldering, and board cleaning.
QA carries out a comprehensive inspection to ensure that the quality is OK.
In the PCBA welding process, the following matters need to be noted:
When soldering PCB circuit boards, first check whether the used model and pin position meet the requirements. Welding first welding edge to the foot of the two pins, in order to position it, and then from left to right top to bottom welding one by one.
Component Welding Order: Resistors, capacitors, diodes, transistors, integrated circuits, high-power tubes, other components for the first small and then large.
Welding, to make the solder joints are surrounded by tin, will be firmly welded to prevent false soldering.
Welding on the tin, tin should not be too much, when the solder joints solder cone, that is, the best.
When taking the resistor, after finding the required resistor, take scissors and cut the required number of resistors and write down the resistance so that you can find it.
Chip and base are oriented, welding, in strict accordance with the direction of the notch pointed out on the PCB board, so that the chip, the base and the PCB three notches are corresponding.
After loading the same specification and then load another specification, try to make the height of the resistor consistent. After welding will be exposed on the surface of the printed circuit board excess pins cut off.
For electrical components (such as capacitors, resistors, etc.) with excessively long pins, cut them short after soldering.
When the circuit is connected, it is best to clean the surface of the circuit with a cleaning agent, in order to prevent the circuit board surface attached to the iron filings make the circuit short circuit.
After welding, use a magnifying glass to view the welded joints, check whether there is a false weld and the occurrence of short-circuit conditions.
Temperature Control:Welding process, the temperature is too high may lead to component damage, the temperature is too low may lead to welding is not strong. Therefore, the need for strict control of the welding temperature, and adjusted as needed in the actual operation.
Time Control: Welding time is too short will lead to welding is not firm, time is too long may be damaged components. Therefore, according to the solder used and welding equipment, reasonable control of the welding time.
Quality of Soldering Joints:The soldering joints should be smooth, neat, without burrs, bubbles and other phenomena. The size of the solder joints should be moderate, not too large or too small to ensure a good electrical connection.
Cleanliness:The cleanliness of PCB and components should be ensured before welding to avoid dust, impurities, etc. affecting the welding quality.
Soldering Order: In mass production, a certain soldering order should be followed, soldering small components first, then large components, in order to prevent displacement or damage of components due to thermal expansion.
Moisture-proof Treatment:After the welding is completed, moisture-proof treatment should be carried out to prevent the performance of the solder joints from being degraded by moisture.
Inspection and Testing:After welding is completed, the circuit board should be inspected and tested to ensure proper functioning and no short-circuits, breaks or other problems.
Safety Issues:In the welding process, attention should be paid to safety issues, to avoid burns, electric shock and other accidents.
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