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Date: | Thu, 18 Nov 2010 07:45:18 -0500 |
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Hey TechNetters,
I've got a couple questions for the solder paste printing gurus:
1. Can someone explain something about transfer efficiency for me? The typical chart (see below) shows a nice, clean set of points, but I know that my process has variation. So is transfer efficiency just about averages? The average volume printed for a specific aperture divided by the aperture volume? Meaning that instead of single points shown in the chart below, box plots would really be more accurate?
Transfer
Efficiency
100% | x x
| x
| x
| x
50% | x
| x
| x
|
0% |_________________________________________________
.3 .4 .5 .6 .7 .8 .9 1.0
Area Ratio
2. What is the 10% rule? I've read a couple of articles that mention the 10% rule, but they don't make it clear what it is. I interpret it to mean that to have an 'acceptable' solder printing process, the standard deviation of the individual data points of paste printed (transfer efficiency) needs to be 10% or less of the average paste transferred. Am I on the right track here?
Thanks,
Ben
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