PCB Tech - PCBA quality control and quality control in SMT production

1. PCBA patch processing quality control

The production and processing process of PCBA involves a series of processes such as PCB board manufacturing, electronic component procurement and inspection supplied by PCBA, SMT chip processing, plug-in processing, program firing, testing, and aging. The supply chain and manufacturing chain are long. Any problem in any link will cause a large number of PCBA boards to fail the quality in batches, and cause undesirable consequences. In view of this situation, the quality control of PCBA patch processing is a very important quality assurance in electronic processing, so what are the main quality control of PCBA processing?

It is particularly important to hold a pre-production meeting after receiving an order for PCBA processing. It is mainly for process analysis of PCBGerber files and submitting a manufacturability report (DFM) according to different customer needs. Many small manufacturers do not pay attention to this, but tend to Here. Not only is it prone to poor quality problems caused by poor PCB design, but also a lot of rework and repair work.

2. Purchase and inspection of electronic components supplied by PCBA

It is necessary to strictly control the procurement channels of electronic components, and must obtain goods from large traders and original manufacturers, so as to avoid the use of second-hand materials and counterfeit materials.

In addition, it is necessary to set up a special PCBA incoming material inspection post to strictly inspect the following items to ensure that the components are fault-free.

PCB: Check the temperature test of the reflow oven, whether the fly-line vias are blocked or leaking, whether the board surface is bent, etc.

IC: Check whether the screen printing is exactly the same as the BOM, and store it at constant temperature and humidity.

Other commonly used materials: check screen printing, appearance, power measurement, etc.

3. SMT assembly

Solder paste printing and reflow oven temperature control system are the key points of assembly, and laser stencils with higher quality requirements and better processing requirements are required. According to the needs of PCB, some need to increase or decrease the steel mesh, or U-shaped holes, only need to make the steel mesh according to the process requirements. Among them, the temperature control of the reflow oven is very important for the wetting of the solder paste and the firmness of the steel mesh, and can be adjusted according to the normal SOP operation guide.

In addition, strict implementation of the AOI test can greatly reduce the defects caused by human factors.

4. Plug-in processing

In the plug-in process, the mold design for wave soldering is the key. How to use the mold to maximize the yield rate is a process that PE engineers must continue to practice and summarize.

5. PCBA processing board test

For orders with PCBA test requirements, the main test content includes ICT (circuit test), FCT (functional test), burn test (aging test), temperature and humidity test, drop test, etc.

Second, the method of quality control in the production process of SMT patch production

In SMT patch production, processing, and manufacturing, quota management should be done for the loss of solder paste, patch glue, and electronic components, as one of the important process control contents. SMT patch production can directly affect the quality of the product, so it is necessary to control the processing parameters, processes, staff, equipment, raw materials, production and processing testing, workshop environment and other factors.

Important posts should have a clear post responsibility system. The operation staff of the patch processing should be strictly trained and assessed, and hold a certificate to work. The smt patch processing plant should have complete and formal manufacturing management methods, such as the implementation of first article inspection, self-inspection, mutual inspection and inspector inspection systems. Those who fail to pass the inspection of the previous process cannot be transferred to the next process.

How to control quality in the production process of SMT patch production

1. Product batch management. The nonconforming product control procedures shall clearly stipulate the isolation, identification, recording, review and handling of nonconforming products. Generally, SMA should not be repaired more than three times, and electronic components should not be repaired more than twice.

2. Maintenance and maintenance of smt patch production equipment. The key equipment should be checked regularly by full-time maintenance staff to keep the equipment in good condition, track and monitor the status of the equipment, discover problems in time, take corrective and preventive measures, and maintain and repair them in a timely manner.

3. Production environment

1. Water and electricity supply.

2. Environmental requirements of SMT patch production and processing production line-temperature, humidity, noise, cleanliness.

3. SMT patch production and processing site (including electronic component library) anti-static system.

4. The entry and exit system, equipment operating procedures, and processing disciplines of the SMT patch production and processing production line.

4. The production site should be reasonably set up and the identification should be correct; the raw materials and products in the warehouse should be classified and stored, neatly stacked, and the ledger should be consistent.

5. Civilized manufacturing. Including: clean, no debris; civilized operation, no savage and disorderly operation behavior. On-site management must have systems, inspections, assessments, and records, and do a good job of "6S" (organization, rectification, cleaning, cleaning, quality, and service) activities every day.