Reasons for poor welding in PCBA manufacturing
What tools are needed for PCBA manufacturing?
The basIC tools required for welding PCBA manufacturing components are SMAll tweezers, iron, tin tape, hot air gun, anti-static bracelet, rosin, alcohol solution, and magnifying glass with desk lamp.
Small tweezers: use small non embroidery steel and pointed tweezers instead of other small tweezers that may have magnetism, because during the bonding process of the patch, the magnetic tweezers will make the components adhere to the tweezers.
Soldering iron: SMT process operator will select a tapered long life soldering iron head with a radius less than 1mm. Two sets of soldering irons are prepared for use when disassembling components.
Hot air gun: The operator of PCBA manufacturer can use a soldering iron to solve the problem when disassembling two or three terminal assemblies, but must use a hot air gun when disassembling the multi lead assembly. The hot-air gun can improve the reusability of disassembLED parts and avoid damaging the pad. In order to carry out frequent component disassembly, it is necessary to select a hot air gun with good performance.
Tin tape: When short circuit occurs in IC lead welding, it is a good choice to use tin tape. The tin strip cannot be used at this time.
Magnifier: SMT technicians should choose a magnifier with a lamp holder instead of a palm magnifier, because welding requires one hand to operate under the magnifier. Lighting the lamp can make the vision clear and increase the visibility of welding.
PCBA manufacturer analyzes the causes and steps of poor welding PCBA manufacturing
1. PCBA process operator shall first check whether there is rust, oil stain and other impurities in the weld, or whether there is bulge and poor contact, which will increase the contact resistance, reduce the current and lead to insufficient weld temperature.
2. The staff of PCBA board and patch processing plant will check whether the current setting meets the process requirements. If the current setting is not increased when the product thickness changes, insufficient current in welding will lead to poor welding.
3. The SMT welder of the PCBA plate manufacturer will check whether the overlap of the weld is normal and whether the overlap of the drive side is reduced or cracked. The reduction of the overlap will make the bonding area of the front and rear steel strips too small, reduce the total stress surface, and cannot withstand greater tension. In particular, the cracking on the drive side will cause stress concentration, and the cracking will become larger and larger, and then pull out.
4. The operator of PCBA processing plant will check whether the pressure of welding wheel is reasonable. If the pressure is insufficient, although the welding controller has a constant current control mode, the actual current will be reduced due to excessive contact resistance. However, if the resistance increases beyond a certain range (usually 15%), it will exceed the limit of current compensation, and the current cannot increase with the increase of resistance, reaching the set value. In this case, the system will give an alarm when it is working normally.