Practical and manual operation /economic price DH-T1 /hot plate recall machine/plant /reballin kit

Half year for whole machine.

Chip bond FAQ;

1. Missing solder

It will cause the off-normal with the manual counterpoint, and there will be a process of automatic correction between welding plate and the bga chip under the effect of the surface tension of the solder ball.

Chip uneven decline result from the uneven heating, or the early returning result in the run-off. If stop the reflow at this time, it will cause the missing solder. So we need to extend the time of soldering temperature. Or we also can increase the soldering temperature to make the degradation of the solder ball uniformity.

2. Short circuit.

When the solder ball arrive in the melting point and is at the status of liquid, the higher time,temperature and pressure will damage the surface tension and supporting role of the solder ball. And then resulting the short circuit. So we need to cut down the time of soldering appropriately, or we can lower the soldering temperature.

3. A chip burst and bubble.

General there will be three situation;

1) First, Chip be affected with damp.

Solution:put the BGA and PCB into the oven about 4 to 8 hours, the temperature of oven setting is 80℃ to 100℃

2) Second, higher temperature

Solution: cut down the soldering time and turn up the bottom temperature to avoid chips directly heated too high.

3) Longer solder time

Solution: cut down the soldering time or move up the upper area a little. And let the bottom heat first, when the bottom temperature is 200 degree, move back the upper area. It can avoid the chip to heating too long.

4. Why the PCB will become black after soldering

General there will be two situation;

1) First,too much repeat welding times

2) Second, there is the problem of the flux paste quality.

Solution: use the better quality flux paste.

5. Why there will be the four corners rugged after the soldering.

General there will be two situation;

1) First, the PCB is not to be installed well or the PCB is out of shape.

Solution: after installing the PCB well. Please check that whether they are on the same line. And adjust the supporting screw to prevent the PCB sinking.

2) Second, the heat absorption rate of the bonding pad inconsistent res luting form the uneven copper foil lead

Solution: since the work environment of the BGA rework station is not sealed, so it cannot arrive the original reflow effect.. For this, we can turn up the temperature of the preheat infrared area. And change to a larger size nozzle to make the BGA chip has a large heating area. It can effectively prevent the absorption of the PCB copper foil too fast.

6. why the bonding pad will drop when dismount the BGA chip.

General there will be several following question;

1) First,welding temperature or soldering time is not enough. In the case of tin ball haven't melt completely to remove the BGA chip

Solution: turn up the temperature or extend the soldering time.

2) Droped bonding pad point was empty on PCB board,not have copper foil lead on bottom bonding pad. Because there is no down-lead to fixed bonding pad the repair process will easy to fall off, but these soldering spot are useless,doesn’t affect use function.

This situation is common, there is no better way to avoid.

3) The problem of PCB board quality.Bonding pad tension and peeling resist coefficient no up to standard.

4) PCB board severity burn-in,in particular the PCB board to use more years.

7. What will you notice when choose the flux and the solder ball?

1) First, Our advice is that the operator should buy the special BGA flux paste. Ifuse the bad quality flux paste, there will be the missing solder and dry joint. And even make the PCB become yellow after soldering.( the storage temperature of the flux paste is not too high, or it will be no use)

2) Second, please pay attention to the date in produced.