1.The solder paste collapses. The form of expression is that the solder paste pattern is not clear and the edges are not uniform or collapsed. Possible causes of this soldering defect: poor solder quality or excessive printing gap and excessive printing pressure.

 

2.Solder paste is connected. The form of expression is the adjacent solder pastes form connection pieces. Possible factors that lead to this welding defect: the stencil is repeatedly printed.

 

3.Solder paste misalignment. Form of expression: The solder paste pattern does not coincide with the welding pad. Possible factors leading to this welding defect: the stencil is misaligned.

 

4.The thickness of the solder paste is too large. The form of expression is that the partial or all welding pad solder paste is too thick or a large amount of solder paste is accumulated, the surface is uneven, and the figure is not clear. Possible causes of the soldering defect:excessive  stencil thickness , too large opening size or the excessive printing gap, and relatively low printing speed.

 

5.The thickness of the solder paste is too small. The form of expression is that the solder paste pattern on the printed board is very thin and the thickness is less than the specified requirements. Possible causes of this welding defect: the stencil is too thin and the solder paste has poor fluidity.

 

6.Solder paste is missing. The form of expression is that some of the welding pads are not covered by solder paste or the solder cover is incomplete. Possible factors leading to this welding defect: stencil opening.