1. Brushed\/trailed
Reasons: the inner diameter of the glue nozzle is too small, the dispensing pressure is too high, the spacing between the glue nozzle and the PCB is too large, the adhesive is expired or poor quality, the adhesive of the patch is too high, the adhesive fails to return to room temperature after being removed from the refrigerator, and the dispensing amount is too much.
Solution: Change the inner diameter of the larger glue nozzle, reduce the dispensing pressure, adjust the \"stop\" height, change the glue, choose the suitable viscosity of the glue, remove from the refrigerator should be restored to room temperature (about 4h), adjust the amount of glue.
2. The glue nozzle of the dispensing machine is blocked, and the amount of the glue nozzle is small or there is no glue point
Cause: The pinhole is not completely cleaned, the patch glue is mixed with impurities, there is plugging phenomenon, and incompatible glue is mixed.
Solution: Change the clean needle, change the better quality of the patch adhesive, and the brand of the patch adhesive should not be mistaken.
3. Dispensing machine empty, only dispensing action, there is no glue amount.
Cause: Mixed with bubbles, glue nozzle blocked.
Solution: The glue in the injection cylinder should be debubbling treatment (especially the glue installed by itself), according to the method of plugging the glue nozzle.
4. Components offset, solidified components shift, serious components pin is not on the pad
Reasons: the amount of glue out of the patch is not uniform (such as two points of the chip component glue one more and one less), the component shift when the patch is placed, the adhesive force of the patch decreases, and the PCB is placed for too long after the glue is semi-cured.
Solution: Check whether the rubber nozzle is blocked, eliminate the phenomenon of uneven glue; After adjusting the working state of the SMT machine, changing the glue and dispensing the PCB should not be placed for too long (less than 4h).
5. After curing, the bonding strength of the components is not enough, lower than the standard value, and the pieces will fall off after wave soldering
Reason: the process parameters are not in place after curing, especially the temperature is not enough; The component size is too large, the heat absorption is large, the light curing lamp is aging, the glue is not enough, the component\/pcb is polluted.
Solution: Adjust the curing curve of the dispensing machine, especially to increase the curing temperature, usually the peak curing temperature of the hot curing glue is very critical, and reaching the peak temperature is easy to cause falling. For the light curing adhesive, it should be observed whether the light curing lamp is aging, whether the lamp has black phenomenon, the amount of glue, and whether the component\/pcb is contaminated.
6. After curing, the pin of the component will float\/shift, and the tin material will enter the pad after wave soldering, and there will be short circuit and open circuit in serious cases
Reasons: the patch glue is not uniform, the amount of patch glue is too much, and the component is offset during the patch.
Solution: Adjust the dispensing machine process parameters, control the dispensing amount, adjust the patch process parameters.
These are the problems often encountered by the dispensing machine, according to the above methods to check, most of the causes of the problem can be found and the corresponding solutions, I hope to provide you with reference and help.