SMT welding, rework and production advantages
The introduction of lead-free chip assembly has always been a challenge for the first assembly, because PCB processing requires rework PCBA maintenance in lead-free environment has high cost, detailed quality information, time and repeatability problems, but due to lead-free requirements, all these problems need attention Because lead-free process requires:
1. Train operators to perform lead-free assembly, maintenance and inspection, and evaluate time and cost
2. Lead free solder is more expensive than traditional solder, such as lead-free wire, electrode and core solder.
3. The processing temperature of lead-free components (about 30-35 ℃) requires higher accuracy and precision.
4. The lead-free process also needs to study and plan the smt processing plant to establish a correct PCBA rework process.
The best practice of PCB assembly rework first requires targeted training and guidance for scientific and technical personnel, and the development of profile based on the characteristics of lead-free process. Rework criteria are defined, and the process starts with the same pipe regardless of whether standard or lead-free solder is required. The required steps are:
Define and execute accurate thermal profiles
2. The faulty component must be removed
3. Clean all rust or solder residues on site and prepare new parts
4. Replace components with new solder and flux and reflow
5. Thorough inspection and rework
In a lead-free environment, accurate and reliable rework is more difficult because PCBA and the components closest to the parts to be repaired must withstand multiple high temperature cycles. In order to protect the stability of the circuit board, the preheating temperature should be set not higher than the glass transition temperature of the PCB data.
The subsequent steps involved in the rework process depend on whether there is a lead-free requirement. The difference between standard and lead-free brings many challenges, which can only be solved by introducing new or changed processes, including stricter and more accurate thermal profiles and extremely high precision in the whole PCBA rework process. This will avoid many costly problems caused by different heat distributions.
Advantages of automatic chip mounting production line
The importance of smt process as a fully automated production line is well known. After all, it provides the efficiency and consistency required for mass PCBA manufacturing. The current market demand makes the importance of automatic assembly more important than ever before. Obviously, its importance comes from its high efficiency and high quality, which makes it easier to enter the market. It can be an important source of competitive advantage. Other key advantages it provides include:
1. Low cost
Professional smt wafer processing plants use the circuit board assembly program before entering the actual production. In turn, this reduces the possibility of errors and delays. During this period, any design errors can also be corrected. In general, this will greatly reduce costs.
2. Reduce the chance of error
The PCB assembly process requires great attention to detail. This is especially true given that circuit boards are getting smaller and smaller. Automatic patch assembly significantly reduces the chance of errors. This means that you can get reliable products without having to face costly mistakes when preparing to ship the final product.
3. Consistent quality
A major advantage of automatic assembly is that it ensures consistent quality. This is also one of the advantages of entering industrialized mass production.
With the miniaturization, it is usually impossible to assemble parts manually, and the assembly process needs to be automated. In addition to these general advantages of automatic assembly, PCB automatic assembly also benefits from the following facts in particular:
1. Large parts need automatic reflow soldering, because it is very difficult to solder pins manually, especially the pins hidden below.
2. QFP is very sensitive to coplanarity and difficult to weld manually.
3. Small parts such as PCB resistors and capacitors are difficult to weld manually.
4. For densely placed PCB components of circuit boards, the consistency of manual welding has always been a problem