20
When the ball reached the melting point, it is in a liquid state , if too long or too high
temperature and pressure, it will destroy surface tension of solder balls and the
supporting role, resulting in short-circuit phenomenon when reflows, the chips fall
entirely on the PCB pads the , so we need to appropriately reduce the heating section
of the third and fourth soldering temperature and time , or reduce the bottom of the
preheat temperature
Attention:
It will cause occur odor in the normal working process In order to assure
safe and healthy operation environment, please keep ventilation in and out of the room
G Outer temperature measurement couple usage
（
A
）
the function of external temperature sensor
a To measure actual temperature more accurately during the welding process
b Because it can move freely, it is more convenient to measure different parts of ready
to be measured component
c It has correct function, which can make the temperature of welding parts is more
familiar with the setting temperature
(B)The installation of couple
a Check that whether the couple line is in good condition
b Put the plug of couple line in the socket of external couple
c After right installation of couple, the touch screen will show the current temperature
of couple
(C)Use the couple to measure actual temperature
a Put the PCB board on the BGA Rework station Use tinfoil paper to fix the couple
line on the PCB board
b Adjust the detector and make it 1-2mm higher than the ready to be measured parts
Picture fifteen
