Views: 40 Author: Site Editor Publish Time: 2022-01-06 Origin: Site
The PCBA processing process involves a series of processes such as PCB board manufacturing, component procurement and inspection of incoming pcba materials, SMT processing, plug-in processing, program firing, testing, aging, etc. The supply chain and manufacturing chain are long, and defects in any link will be As a result, the quality of PCBA boards in large quantities is not satisfactory, resulting in serious consequences. Therefore, the control of the entire pcba patch processing is particularly important. This article mainly analyzes the following aspects.
1. PCB circuit board manufacturing
It is particularly important to hold a pre-production meeting after receiving an order for PCBA processing. It is mainly to analyze the process of PCB Gerber files and submit a manufacturability report (DFM) according to different customer needs. Many small manufacturers do not pay attention to this, but tend to tend to here. Not only is it easy to produce poor quality problems caused by poor PCB design, but also a lot of rework and repair work.
2. Component procurement and inspection of incoming PCBA materials
It is necessary to strictly control the procurement channels of components, and the goods must be obtained 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 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 vias without flying leads are plugged holes or ink leakage, whether the board surface is bent, etc.
IC: Check whether the screen printing is exactly the same as the BOM, and keep it at constant temperature and humidity.
Other commonly used materials: check screen printing, appearance, power-on measurements, etc.
3. SMT assembly
Solder paste printing and reflow oven temperature control system are key points of assembly, and laser stencils with higher quality requirements and better processing requirements need to be used. According to the requirements of the PCB, some need to increase or decrease the steel mesh holes, or U-shaped holes, just make the steel mesh according to the process requirements. The temperature control of the reflow oven is very important for the wetting of the solder paste and the firmness of the stencil welding, which can be adjusted according to the normal SOP operation guidelines.
In addition, the strict implementation of 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 molds to maximize yield is a process that PE engineers must continue to practice and summarize.
5. Program firing
In the previous DFM report, customers can be advised to set up some test points on the PCB (test points) to test the circuit continuity of the circuit during PCBA processing after all parts are soldered on the PCB. If possible, you can ask the customer to provide a program, and burn the program into the main control IC through the programmer, which can test various touch actions more intuitively in order to verify the functional integrity of the entire PCBA.
6. PCBA processing board test
For orders with PCBA test requirements, the main test contents include ICT (circuit test), FCT (functional test), burn test (aging test), temperature and humidity test, drop test, etc.