Stencil
Printing Process
80% of
However, don’t we shall be responsible as well on inspecting the
printing processes and its failures instead of depending machine
itself?
Stencil Detailed Specifications
Factory engineers normally request the info of Mask opening ratio
and aperture to the mask supplier, but the info of processing
tolerance and surface accuracy have been neglected.
When a new stencil is being placed, precise checking is skipped.
When comes to the occurrences of printing issues, only machine
parameter adjustment such as auto cleaning being carried out by
local engineers instead of truly do manual checking on the actual
printing condition.
Nowadays, laser stencil is supported by most of the factory;
however, it’s still quite difficult to maintain a good printing
condition without high tolerance of stencil opening surface.
As what we can see from the photo shown above, there are cases
happen regularly; although both regular automatic cleaning and
manual cleaning at every 30 minutes are taken, the printing result
is still not so stable.
Why? The reason is people never take positive and relevant QC
actions beyond the “ok” sign shown by
Analysis.
|
|
Thickness |
Aperture Size |
Taper |
|
Original Specs |
150 μm |
200 μm |
- |
|
Result |
140.24 μm |
208.46 μm/ 221.72 μm |
13.26 μm |
|
Target |
150μm ± 5 μm |
200 μm ± 5 μm/
205 μm ± 5 μm |
10 μm |
From the analysis shown above, taper must be below 10 μm and its
tolerance must be below 5 μm. The current opening surface accuracy
is 7-10 μm.
Below 5 μm
To achieve higher accuracy of laser stencil, higher power of laser
at the right process time and higher quality grinding will be
necessary, and it will be able to offer 1-4 μm surface tolerance.
:: Quoted by Mr. Berdie,