SMT solder paste offset is a poor performance of the solder paste printing machine printing (other bad also include: flatness, thickness, leakage printing), if this bad through the SPI inspection machine timely found can be very good to deal with, if it is soldering after causing bad, either rework (time-consuming and laborious), or directly scrap. Therefore, this kind of SMD solder paste offset, we need to analyze the reasons.
SMD solder paste offset causes generally common reasons are the following
1. Solder paste problem
Solder paste is a mixture of tin powder alloy and flux (flux contains solvents, rosin, thickeners, active agents), if the paste stirring viscosity is not strong, the phenomenon of broken flow (refers to the paste stirred up with a stick appears dripping), then the paste in the printing time is easy due to the amount of large lead to the outside of the pad diffusion, resulting in deviation, so the paste in use before the need for full warming stirring.
2. Stencil problem
Stencil is a necessary auxiliary tool for printing solder paste, can be seen as a solder paste leakage mold, solder paste printing offset, may be a larger stencil opening, may also be a stencil opening offset caused.
3. Solder paste printing scraper pressure
Solder paste printing to the PCB pad, the need to scraper movement, scraper pressure is small, it will lead to more solder paste leakage printing, combined with poor adhesion of the solder paste, it is easy to cause bias, in addition, if the pressure is too large, it will cause less solder paste, so in the actual production process, you need to set a standard value.
4. Solder paste printing machine clamp fixture instability
pcb to the workbench area needs to be clamped to maintain a stable, if the fixture is unstable, solder paste printing is not aligned with the pcb pads, it will cause a deviation
The above four reasons are common causes of solder paste offset, in actual production, if you encounter this kind of solder paste printing bad situation, you need to specific analysis of specific problems, find the cause, solve the problem and improve the process.
Features of NeoDen FP2636
1. T screw rod regulating handle, ensure adjustment accuracy and levelness of PCB fixed plane, minimum lead pitch achieved 1mm.
2. Adjustable rubber footing, ensure the flatness while operating.
3. Straight damping shaft, ensure the stencil fixed frame can be fastened at random angles, to improve convenience while operating.
4. L supports and pins to fix PCB, applicable for multiple types PCBs’ fixation and printing, more flexible and convenient.
5. Support for single sided as well as double sided PCB.
