Solder paste printing quality analysis
the quality problem caused by poor solder paste printing common are the following:
①Solder paste insufficient (lack of partial even lack of overall) will result in welding components solder tin insufficient solder tin, parts open, component misalignment, components erect.
②Paste adhesions will cause short circuits, components deviation after soldering.
③Solder paste printing overall deviation will result in the entire board components poor welding, such as a small tin, open, deviation, vertical pieces.
④Solder paste icicles easy cause short circuit after welding.

1.The main factors that lead to insufficient solder paste:
1.1. Printing work,do not add solder paste timely.
1.2. Solder paste quality abnormalities, which mixed with lumps and other foreign matter.
1.3. Previously unused solder paste has expired, secondary used.
1.4. Board quality problems, there are inconspicuous covering on pad, for example, printed onto pad solder resist (green oil).
1.5. Circuit board in a printer stationary gripping loosening.
1.6. Drain printed solder paste stencil Bohou uneven.
1.7. Solder paste stencil printing or drain board contaminants (such as PCB packaging, stencil wiping paper, foreign objects floating in the air environment, etc.).
1.8, paste scraper damage, stencil damage.
1.9, solder paste squeegee pressure, angle, speed, and release speed parameter setting device unsuitable.
1.10 solder paste printing is complete, because the human factor was accidentally knocked.

2, the main factors leading to the adhesion of solder paste
2.1, the circuit board design defects, pad pitch is too small.
2.2, stencil problems, holes malposition.
2.3, stencil did not wipe clean.
2.4, so that the solder paste stencil problem bad off.
2.5, poor solder performance, viscosity, collapse failed.
2.6, the circuit board is fixed in the press sandwiched loose.
2.7, solder paste squeegee pressure, angle, speed, and release speed parameter setting device unsuitable.
2.8 After the solder paste printing is complete, because the human factor is squeezed adhesion.

3, the main factors leading to the overall deviation of solder paste printing
3.1, the circuit board positioning reference point is not clear.
Reference point 3.2, the circuit board positioning reference point and the stencil is not aligned.
3.3, the circuit board is fixed in the press loose clamp positioning thimble is not in place.
3.4, optical positioning system of printer failure.
3.5, solder paste rain printing stencil apertures circuit board design files do not match.

4, the main factors leading to a sharp pull printing paste
4.1, paste viscosity and other performance parameters have problems.
4.2, stripping parameters printed circuit board and the drain when the setting screen separation problem,
4.3, the pore walls of rain printing stencil Lou have burr.

Chip Quality Analysis
SMT placement common quality problems tainted parts, side parts, turning parts, deviation, loss of parts.

1, the main factors leading to patches of missing parts
1.1 components feed shelf (feeder) could not imagine sending bits.
1.2, components nozzle of the gas blockage and damage the nozzle, nozzle height is incorrect.
1.3, the true air circuit of device failure, clogging.
1.4, bad circuit board stock, resulting in deformation.
1.5, no solder paste on the circuit board pad or too little solder paste.
1.6, component quality issues, thickness of the same species inconsistent .
1.7 Mounter calling program errors and omissions, or for the choice of components thickness parameter is incorrect programming.
1.8, the human factor accidentally knocked.

2,the main factor of resulting in turn parts side pieces when SMC resistors SMD ,
2.1 components feed shelf (feeder) feeding exception.
2.2 the height of nozzle head incorrect.
2.3, the height of grasping the material placement head incorrect.
2.4, charging the pore size of braid component is too large , component flip due to vibration.
2.5 Bulk loading direction reversed when taping.

3, the main factors leading components patch Deviation
3.1, when the placement machine programming, XY coordinate components is incorrect.
3.2, patch nozzle reasons, the suction instability.

4, the main factors leading to patch damaged components
4.1, positioning thimble too high, so the position of the board is too high, when mounting components are squeezed.
4.2, when the placement machine programming, Z axis coordinate components is incorrect.
4.3 spring nozzle placement head is stuck.