Causes of virtual welding in Smt patch processing

Posted by davidsmithsmile on April 23rd, 2021

Recently, in the front-end consultation of the SMT PCB processing plant, I also summarized some issues that everyone is very concerned about in the patch processing. First of all, everyone is asked the most frequently about the false soldering. Today I will follow everyone. Analyze the reasons for the virtual soldering in some smt patch processing in three dimensions?

1. Welding caused by process factors
1. Missing solder paste
2. Insufficient amount of solder paste applied
3. Steel mesh, aging, poor leakage
2. Virtual soldering caused by PCB factors
1. PCB pads are oxidized and have poor solderability
2. There are via holes on the pads
3. Welding caused by component factors
1. Deformation of component pins
2. Oxidation of component pins
4. Welding caused by equipment factors
1. The placement machine moves too fast in the PCB transmission and positioning, and the inertia is too large to cause the displacement of heavier components
2. The SPI solder paste detector and AOI testing equipment did not detect the related solder paste coating and placement problems in time
5. Welding caused by design factors
1. The size of the pad and the component pin does not match
2. Virtual soldering caused by metallized holes on the pad
Six, false welding caused by operator factors
1. Abnormal operation during PCB baking and transfer, causing PCB deformation
2. Illegal operations in the assembly and transfer of finished products

Basically, in smt chip manufacturers, there are so many reasons for the false welding of finished products in PCB manufacturing processing, and different links will cause the probability of false welding to be different, even only in the theory, but the actual low-level errors are generally not Will appear.