Hello there,
I was working on some analysis work on BGA pad diameters and its
correlation to other factors when I come across this Table 6 in
IPC-7095. I cannot explain the differences found which I highlighted in
bold. The table specifies :
Nominal ball szie Reduction Nominal Land Dia. Land Variation
0.75 25% 0.55 (27%)
0.60 - 0.50
0.60 25% 0.45 (25%)
0.50 - 0.40
0.50 20% 0.40 (20%)
0.45 - 0.35
0.45 20% 0.35 (22%)
0.35 - 0.25
0.40 20% 0.30 (25%)
0.35 - 0.20
0.30 20% 0.25 (17%)
0.25 - 0.20
Anyone care to shed a light on the difference in the two percentages or
how the Nominal Land Dia. value come about or agreed upon. Your answers
will be deeply appreciated.
Regards,
Wee Mei
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