Turnkey pcb manufacturing common poor printing analysis and solutions

1,The printing position is deviated

Cause: The poor alignment of the stenciland the PCB is the main reason, and there are cases where the stencilis poorly produced; the printing machine is not accurate enoughduring the turnkey pcb manufacturing process.

Hazard: Easy to cause bridgingconnection.

Countermeasure:: adjust the stencil position; adjust the printing machine.

2,Insufficient filling

Insufficient filling is phenomenon in which the amount of solder paste supplied to the PCB pad is insufficient. Unfilled, lack of soldering, less soldering, dents, etc. all belong toinsufficientphenomenon. Because the insufficient filling amount is related to various factors such as printing pressure, scrapperspeed, off-grid conditions, solder paste performance and state, stencilmanufacturing method, and poor stencilcleaning, it is very important to optimize the printing conditions during the turnkey pcb manufacturing process.

3, Penetration

Penetration refers to the phenomenon that flux penetrates around the pad being filled. The reasons for the infiltration are excessive pressure of the printing scrapper, excessive gap between the stenciland the PCB, etc. Measures such as adjusting the printing parameters and cleaning the stencilin time should be taken.

4,Bridge connection

Bridging connection is the phenomenon in which solder paste is printed onto adjacent pads. Possible reasons are the positional deviation of the stenciland the PCB, the printing pressure is large, the printing gap is large, and the reverse side of the stencilis not clean. In the turnkey pcb manufacturing process, the printing parameters should be adjustedproperly and the template should be cleaned in time.

5, The solder paste pattern has depression

Cause: The blade pressure is too large; the hardness of the scrapperis not enough; the stencil window is too large.

Hazard: The amount of solder is not enough, it is easy to appear solder joint, and the solder joint strength is not enough.

Countermeasure: Adjust the printing pressure during turnkey pcb manufacturing; replace with metal scraper; improvestencilwindow design.

6,Too much solder paste

Cause: The stencilwindow size is too large; the gap between thestenciland the PCB is too large.

Hazard: Easy to cause bridging.

Countermeasure: Check the size of the stencilwindow; adjust the printing parameters, especially the gap of the PCB template.

7, The amount of solder paste is uneven, there are breakpoints

Cause: The stencilwindow wall is not smooth; the number of times of printing is too much, and the residual solder paste is not wiped off in time; solder paste thixotropy is bad.

Hazard: It is easy to cause insufficient solder, such as solder joints and defects.

Countermeasure:Wipe the stencilduring turnkey pcb manufacturing.

8, Graphics contamination

Cause: The timesof stencil printing is too many, and it cannot be wiped clean in time; the quality of solder paste is poor; there is jitter on the off-grid.

Hazard: Easy to cause bridgingconnection.

Countermeasure: Scrubthe stencil; change the solder paste; adjust the machine.

In short, pcb manufacturer should pay attention to the parameters of the solder paste which will change at any timeduring solder paste printing , such as particle size, shape, thixotropy, flux performance, etc. In addition, the parameters of the printing machine will also cause changes, such as printing pressure, speed, environmenttemperature and so on. Solder paste printing quality has a great influence on the quality of the soldering. Therefore, in the turnkey pcb manufacturing process, each parameter in the printing process should be carefully treatedby pcb manufacturer, and the relevant data should be observed and recorded frequently.