2019-BTU-web-Vacuum-reflow-Dimock.pdf - 第21页
Conclusions: 1. Nothing removes most of the empty spaces from something 3. V acuum levels as soft as 245 T orr and short as 5 seconds remove some of the empty spaces. 4. Hard vacuu m of 20 T orr with a hold time of 30 se…
Vacuum level % Voids @ 20 Sec hold time
Torr Sec MLF100 MLF52 MLF16
760 0 38.54 27.81 20.37
500 20 26.08
120 20 6.7 4.1 2.4
45 20 4.2 2.1 1.3
20 20 3.35 1.24 1.14
6 20 1.86 1.86 0.75
> 10%
< 10%
< 3%
500 30 26.8
250 30 9.79 5.62 5.21
85 30 7.4 3.1 2.5
20 30 1.93 0.72 1.04
6 30 1.5 0.66 0.96
Vacuum level % Voids @ 30 Sec hold time
Conclusions:
Conclusions:
1. Nothing removes most of the empty spaces
from something
3. Vacuum levels as soft as 245 Torr and short as
5 seconds remove some of the empty spaces.
4. Hard vacuum of 20 Torr with a hold time of 30 seconds
results in void levels of about 2% in MFL 100s
2. It is easier to remove voids from small components
than large ones.
Things to consider
Voids located at critical points (“hot spots”)
may be the real issue
Void Size
Large voids are most likely the primary concern
Small voids may not be troublesome
Cumulative voiding may only have a secondary affect