PCBA manufacturing process involves PCB board manufacturing, component procurement and inspection, chip processing, plug-in processing, program burn-in, testing, aging and a series of processes, supply and manufacturing chain is relatively long, any defect in one link will cause a large number of PCBA board bad, resulting in serious consequences. Thus, it is particularly important to control the whole PCBA manufacturing process. This article focuses on the following aspects of the analysis.
1. PCB board manufacturing
Received PCBA orders held pre-production meeting is particularly important, mainly for the PCB Gerber file for process analysis, and targeted to customers to submit manufacturability reports, many small factories do not focus on this, but often prone to quality problems caused by poor PCB design, resulting in a large number of rework and repair work. Production is no exception, you need to think twice before you act and do a good job in advance. For example, when analyzing PCB files, for some smaller and prone to failure of the material, be sure to avoid higher materials in the structure layout, so that the rework iron head easy to operate; PCB hole spacing and the board’s load-bearing relationship, do not cause bending or fracture; wiring whether to consider high-frequency signal interference, impedance and other key factors.
2. Component procurement and inspection
Component procurement requires strict control of the channel, must be from large traders and original factory pickup, 100% to avoid second-hand materials and fake materials. In addition, set up special incoming material inspection positions, strict inspection of the following items to ensure that the components are fault-free.
PCB: reflow oven temperature test, ban on flying lines, whether the hole is blocked or leaking ink, whether the board is bent, etc.
IC: check whether the silkscreen and BOM are exactly the same, and do constant temperature and humidity preservation.
Other common materials: check the silkscreen, appearance, power measurement value, etc.
Inspection items in accordance with the sampling method, the proportion of 1-3% in general
3. Patch processing
Solder paste printing and reflow oven temperature control is the key point, need to use good quality and meet the process requirements laser stencil is very important. According to the requirements of the PCB, part of the need to increase or reduce the stencil hole, or the use of U-shaped holes, according to the process requirements for the production of stencils. Reflow soldering oven temperature and speed control is critical for solder paste infiltration and solder reliability, according to the normal SOP operating guidelines for control. In addition, the need for strict implementation of SMT AOI machine inspection to minimize the human factor caused by bad.
4. Insertion processing
Plug-in process, for over-wave soldering mold design is the key point. How to use the mold can maximize the probability of providing good products after the furnace, which is the PE engineers must continue to practice and experience in the process.
5. Program firing
In the preliminary DFM report, you can suggest to the customer to set some test points (Test Points) on the PCB, the purpose is to test the PCB and the PCBA circuit conductivity after soldering all components. If there are conditions, you can ask the customer to provide the program and burn the program into the main control IC through burners (such as ST-LINK, J-LINK, etc.), so that you can test the functional changes brought about by various touch actions more intuitively, and thus test the functional integrity of the whole PCBA.
6. PCBA board testing
For orders with PCBA testing requirements, the main test content contains ICT (In Circuit Test), FCT (Function Test), Burn In Test (aging test), temperature and humidity test, drop test, etc., specifically according to the customer’s test program operation and summary report data can be.
Post time: Mar-07-2022