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3.2.5.3. Instruction about Soldering Printing
Excellent printing graphics should be uniform in both vertical and horizontal direction,full,clean all round, solder
paste fill solder pad. Using above such printing graphics device, after reflow soldering,will get good welding
effect then.
Defects
Reasons
Issues
Solutions
Solder paste
graphics
dislocation
Holes on the stencil not good
match with solder pad; No
enough precision of the Printing
machine
Easily cause
bridge connection
Adjust the stencil position;
Adjust the printing machine.
Solder paste
graphics have
icicles and dents
Scraper’s pressure is too large;
Rubber scraper’s hardness is not
enough;
Holes are too big in the stencil
Solder paste’s required
volume is not enough,
easy to appear faulty
soldering;solder joint
strength is not enough.
Adjust the printing pressure;
Use metal scraper; Improved
holes designing in the
stencil.Too much solder paste
Too much solder
paste
Holes are too big in the stencil;
The gap is too big between
stencil and PCB.
Easily cause
bridge connection
Check the holes size in
stencil; Adjust the parameters
of printing, especially the gap
between PCB and stencil
Graphic
uneven(have
breakpoints)
Holes’ wall are not smoothness
enough; not wipe residual solder
paste in using for many times;
Solder paste’s thixotropy is bad.
Easy cause no enough
solder paste, lead to
the problem such as
faulty soldering.
Wipe the stencil
Contamination of
the graphics
Not wipe residual solder paste in
stencil after using for many
times; Poor quality of solder
paste; Shake problem when
getting the stencil way
Easily cause
bridge connection
Wipe and clean stencil;
replace solder paste;adjust
the machine.
