PCBA Tech - Inherent quality problems of SMT processed products

More and more people are aware of the adverse consequences caused by the poor quality of SMT surface mount products. This shows that manufacturers urgently need to check the production process and install necessary automatic optical monitoring devices to reduce the loss caused by poor quality. . Users' requirements for the miniaturization of electronic products are increasing. It is needed now, and in the future, mobile phones, computers, digital cameras, etc. that are smaller, better quality, better performance, and more efficient are needed. With people's demand for miniaturization of electronic products, they are faced with a severe challenge to produce products with hundreds of parts that are invisible under normal conditions. The surface mount manufacturing industry faces the following main challenges:

The first is to try to assemble sand-sized components on hundreds or even millions of PCBs.

The distribution density of PCB components is extremely high. During the assembly process, the equipment used may have accidental or frequent systematic positioning deviations due to many factors. These factors include: aging problems; problems with the ability to place 0402 or 0201 components; setting problems to maintain accurate placement positioning; problems with the time before the 0402 type board is produced due to the accumulated debris suction nozzle; The number of installed components; the ability of the operator to turn the reel. In addition, there is also the quality problem of standard solder. These are enough to make people understand why the cost of inferior product quality is huge. When the error is discovered, it is too late. Some errors are found during online testing. Up to 60% of the errors can be found in online testing. Many products cannot be tested online due to high assembly density or design features; some errors are Found during functional testing (if this type of testing is performed on the product). Most of the defects are discovered by consumers. Most of them have either suffered from inferior products, or have read product reports about poor quality records and a large number of returns in newspapers, which is much more expensive than repairing.

Secondly, these errors are caused by the absence of automatic optical inspection equipment during the production process. Many of these errors cannot be detected by the naked eye. Even if there is time to inspect a board for a few hours, it will not help. However, the only detection method used in many countries, including China, is visual inspection. Even more surprising is that the average time it takes for each inspector to inspect a circuit board with more than 400 small components is 10 minutes. For the same inspector, even if he was given 40 minutes to inspect a circuit board with larger components and simpler components, 90% of the problems could not be seen. And this problem is not only related to medium-to-high-capacity SMT. Note that high-mix-low-volume surface mount products have similar problems. In many cases, rapid conversion often causes serious problems in the SMT process.