With the increasing use of precision dispensing valves in dispensing production, the problem of precise dispensing valve seriously restricts the efficiency and quality of production in the production process. What are the common defects of precision dispensing valves from the middle technology to users?
1, drawing / trailing: drawing / trailing, the most common problem in glue:
The reason: the needle diameter is too small, the dispensing pressure is too high, the glue mouth from the PCB spacing is too large, the adhesive storage time and the quality is not good, the adhesive patch is too high, failed to recover from the refrigerator to the room temperature, the quantity of cement too much are the cause of this problem.
The solution is to replace the larger inner diameter needles, reduce the dispensing pressure, adjust the "stop" height, change the glue and choose the glue with suitable viscosity, remove it from the fridge and restore to room temperature (about 4h), and adjust the amount of glue.
2, needle plug:: the needle mouth out of glue is too little out of glue.
The causes are: not completely clean in the pinhole, the patch glue is mixed with impurities, and there is a hole in the hole, and the incompatible glue is mixed.
Solution: change the clean needle, change the quality of the patch glue, the label of the patch glue can't be mistaken.
3, empty:: only appear glue action, no glue.
The cause: mixed with bubbles, needle plugging.
Solution: the glue in the injection cylinder must be deactivated, and it is solved according to the blockage of the needle.
4, component offset:: the solidified component is displaced, and the component pin is not on the pad.
The reason: the adhesive glue volume does not mean (for example, two chip components glue a little more than a little), when the patch element shift, patch adhesive force, decreased, after dispensing PCB placed in a long time by semi solidified glue.
Solution: check whether there is a blockage in the needle, exclude the problem of uneven glue, adjust the placement machine status, change the glue, after dispensing, the PCB placement time should be less than 4 hours.