2019-BTU-web-Vacuum-reflow-Dimock.pdf - 第10页
Four Basic V acuum Process Step s Not including transpor t Pump Down V acuum le vel Hold time Equalizati on Rate at w hich vacuum is applied T orr /sec The amount of vacuum T orr The time at the chosen vacuum le vel Seco…
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
Pump Down
Rate at which vacuum is applied
Too fast
Voids explode when leaving the joint
causing solder balls and splatter
We experienced parts moving and flipping
with a 100 Torr/ sec pump down.
0
100
200
300
400
500
600
700
800
30 to 60 Torr / sec
at hard vacuum levels