What is the PCBA virtual welding?The solution?
1，what is virtual welding:
Virtual welding, also known as fake welding, is a kind of state that is not connected at the time of passing, and belongs to a kind of bad welding, which is a very important reason for the high early PCBA repair rate.PCBA virtual welding is often referred to as cold welding. The surface appears to be welded together, but the actual inside is not connected, or is in the middle unstable state that may or may not be connected, which affects the circuit characteristics and may lead to the unqualified PCB board or scrap.Therefore, it is important to pay attention to the phenomenon of PCBA virtual welding. As a professional PCBA processing plant, jingbang technology of shenzhen has rich experience in PCBA production and processing.
Ii. Causes of PCBA virtual welding are as follows:
1,Oxidation of welding disc and component pin
The oxidation of the solder plate and the lead pin of the component parts can easily lead to the solder paste being unable to fully infiltrate the solder plate under the state of liquefaction during reflow welding and the tin climbing, leading to the virtual soldering.
2, less tin
In the process of solder paste printing, due to the small opening of steel mesh or the small pressure of scraper, there is less tin, so that soldering, the amount of solder paste is not enough, the components cannot be fully welded, resulting in PCBA virtual welding.
3,The temperature is too high or too low
In addition to the low temperature will cause PCBA virtual welding, the temperature should not be too high.Because the temperature is too high, not only does the soldering tin flow, but also increases the surface oxidation rate, which may also lead to virtual soldering, or not soldering.
4,Low melting point of tin paste
For some low temperature solder paste, the melting point is relatively low, and the thermal expansion coefficient of the element pin is different from that of the plate material of the fixed element. Over time, with the change of the working temperature of the element, the phenomenon of PCBA virtual welding will occur under the action of thermal expansion and cold shrinkage.
5,Solder paste quality problem
The bad quality of solder paste, the easy oxidation of solder paste and the loss of flux will directly affect the soldering performance of solder paste and lead to virtual soldering.
In general, the situation of virtual welding produced by PCBA is complex and requires strict process control in production and optimization of process flow.
Iii. Solutions to PCBA virtual welding:
PCBA virtual welding can reduce the production of virtual welding through the early material storage and the later processing, which requires our electronic processing enterprises to strictly standardize the production management process. Specific measures are as follows:
1,Make sure the components are kept damp proof;
2,The direct plug can be slightly polished;
3,In welding, soldering paste and flux can be used. It is better to use the reflow soldering machine.
4,Reasonably select good PCB substrate quality.virtual welding
In the process of PCBA, welding is the important factor affecting the quality of circuit board, once appear, virtual welding phenomenon need to rework, not only increase the work pressure, will also reduce the production efficiency, and causes losses to the enterprise, so try to avoid a virtual welding phenomenon, completes the inspection work, and once appear, PCBA virtual welding will need to find the reason and solve immediately.
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