2019-BTU-web-Vacuum-reflow-Dimock.pdf - 第9页
V acuum Chamber is place d betw een the last heated zone and cooling section w ith automated board transfer in and out of the chamber Inline vacuum reflow oven
Vapor phase reflow + vacuum: expensive, slow, messy
Large voids are more likely to contact exposed solder surfaces and escape
Why Vacuum reflow?
Convection reflow + vacuum:
no vapor, faster throughput, minimum mess
Vacuum reflow has been shown to be effective at reducing solder voids
Voids grow as surrounding pressure decreases (Pascal’s Law)
Large voids have an opportunity to combine and become larger voids
Vacuum Chamber is placed
between the last heated zone and cooling section
with automated board transfer in and out of the chamber
Inline vacuum reflow oven
Four Basic Vacuum Process Steps
Not including transport
Pump Down
Vacuum level
Hold time
Equalization
Rate at which vacuum is applied Torr /sec
The amount of vacuum Torr
The time at the chosen vacuum level Seconds
The rate at which the chamber is Torr /sec
returned to room atmosphere