The main function object of SMT solder paste printing machine is solder paste and circuit board. The solder paste and the pads on the circuit board are combined through the function of solder paste printing machine, and then the chip components are pasted on the corresponding pads of the circuit board brushed with solder paste through the solder paste printing machine. After reflow welding, the circuit board becomes a finished electronic product.

1、 Insufficient solder paste after printing by SMT solder paste printer

Cause: it occurs during steel plate printing, which may be caused by too thick wire diameter of mesh cloth and too thin plate film

resolvent:

1. To increase the thickness of a screen, such as a cloth or a printing paste

2. Improve the accuracy of printing.

3. Adjust the parameters of solder paste printing.

2、 SMT solder paste printing machine has too much solder paste after printing

Reason: similar to "bridging"

resolvent:

1. Reduce the thickness of the printed solder paste.

2. Improve the accuracy of printing.

3. Adjust the parameters of solder paste printing.

3、 Collapse of SMT solder paste printer after printing solder paste:

Reason: similar to "bridging".

resolvent:

1. Increase the percentage of metal in the solder paste.

2. Increase the paste viscosity.

3. Reduce the particle size of solder paste.

4. Reduce the ambient temperature.

5. Reduce the thickness of printing paste.

6. Reduce the pressure exerted by part placement.

4、 Insufficient adhesion of solder paste after printing solder paste by SMT solder paste printer:

Cause: high ambient temperature and high wind speed cause too much solvent escape in solder paste and too large particle size of tin powder. Eliminate the conditions of solvent escape (such as reducing room temperature, reducing blowing, etc.).

resolvent:

1. Reduce the percentage of metal content.

2. Reduce the viscosity of solder paste.

3. Reduce the particle size of solder paste.

4. Adjust the distribution of solder paste particle size.

5、 Solder paste blur after SMT solder paste printing machine prints solder paste:

Causes: the causes of formation are very similar to bridging or collapse, but most of the reasons for poor printing construction, such as too much pressure, insufficient overhead height, etc.

resolvent:

1. Increase the percentage of metal content.

2. Increase the paste viscosity.

3. Adjust the ambient temperature.

4. Adjust the parameters of solder paste printing.

6、 The printed circuit board of SMT solder paste printing machine has the problem of overlapping tin

Reasons: small amount of tin powder, low viscosity, large particle size, room temperature, too thick printing paste, too high placement pressure, etc. (usually, when there is a little paste between the two welding pads, it will often be pulled back by the main tin body on each pad during high-temperature fusion welding. Once it cannot be pulled back, it will cause short circuit or tin ball, which is very dangerous to the fine spacing).

resolvent:

1. Increase the proportion of metal components in solder paste (to more than 88%).

2. Increase the viscosity of solder paste (above 700000 CPS)

3. Reduce the particle size of tin powder (e.g. from 200 mesh to 300 mesh)

4. Reduce the ambient temperature (below 27oc)

5. Reduce the thickness of the printed solder paste (reduce to the overhead height snap-off, reduce the scraper pressure and speed)

6. Enhance the accuracy of printing paste.

7. Adjust various construction parameters of printing paste.

8. Reduce the pressure exerted by part placement.

9. Adjust the temperature curve of preheating and fusion welding.

7、 The printed circuit board of SMT solder paste printing machine has cortical burst

Cause: because the activator in the solder paste flux printed by SMT solder paste printing machine is too strong, when the ambient temperature is too high and the amount of lead is too much, the oxide layer on the outer layer of particles will be peeled off.

resolvent:

1. Avoid exposing the solder paste to moisture.

2. Reduce the activity of flux in solder paste.

3. Reduce the lead content in metals.