Useful Tips of QC in
Printing Process
Quality printing results are mainly affected by 3 elements below
which must be taken care of during printing process.
-The control on cleanliness must be done every 12 hours.
-It is compulsory for 1005 or 0.5 pitch QFP
-Reason: To prevent clogging.
(Clog: the surface of squeegee will be clogged with the solder
paste, or the paste itself will be clogged in the opening when the
cleaning is insufficient).
-Both handy and auto are available for ultrasonic mask
cleaner.
-Confirm the opening of the metal mask (especially corners) by
lighting up from the bottom after cleaning.
-Please be advised that do not put aluminum tape to fix the mask and
its flame. Bonding is the most advisable method for fixing mask.
-Concave parts on the mask will affect flattens of metal mask which
not only causes the difficulties of paste removal but also will
damage the squeegees.
-Cleanliness is a must and to be done in every 12 hours (same way of
cleaning)
-Ensure the sharpness of the edges after cleaning.
-Rubber squeegee does not harm the mask; printing pressure
adjustment must be done for big or small opening mask.
-Squeegee edge must be checked and changed daily.
-Changing the pressure without checking the squeegee condition will
worsen the printing result.
-Metal squeegee stabilize printing although it could life span of
mask will be shorter.
-The condition of mask must be monitored regularly, otherwise when
the mask/ metal squeegee wears off, more defectives generated (less
solder, bridge, etc.) because of poor ability of paste removal.
-It is advisable that before printing, paste must be stirred
properly as like the image mixing of jam and cream.
-Color is defected when the mixed paste is not equally and
sufficiently stirred; in the other hand, it will be too soft when it
is stirred excessively.
-Inner/ outer lid of can must be always tighten and sealed
properly.
-Excessive paste flow from squeegee must be removed to prevent
clogging.
-Maintaining cautious on the smells of solder. Unfavorable solder
will incur awful odors.
:: Quoted by Rising Dragon, 9-Nov-2009 ::