Tips when soldering U6960/TPS62180

[aed040]

I am trying to fix my macbook.

Can you give me some tips when replacing the U6960 chip.
What Hotair temp and fan speed do you use?

How long do you usually wait before you can remove a chip? Ive been watching repair videos and they can easily remove a chip after a few seconds but I've been heating the part on a test board for almost a minute and it wont budge.

Does a really good flux help in melting the solder? I am not sure if my amtech flux is fake that is why its taking a long time.

The flux is also being blown away from the component I want to remove which then leaves it looking dry, does that mean I have a very strong air?

Which is better smaller or bigger hotair nozzle?

Sorry If I have a lot of questions, I just want to know what I am doing wrong.

[dellxps15]

hi it depends from many circumstancies. ill try to explain as much as i can by point:

1° pcb size matter.. small macbook air absorbe less heat then a imac 27 inch board.
2° what hot air and how much old is it ?
3° i have 6-7yr old atten 8586 with hot air nozzle replaced once. i use 390° (screw set to get much hotter air possible) and fan speed around 6-7, but keep in mind that when it was new i was ok to set fair speed to 4 for almost all board
3° nozzle size depend on component size, pcb size, solder type. on a small macbook air with leaded solder (maybe already reworked) u can use medium (1cm diameter)set 380° and air flow 5; on lead free big pcb i sometimes go with no nozzle, 390° and fan speed to 6-7(remember my hot air is old)
fan speed should be no more to make resistor get blown away easy (without flux).
4° flux must be not sticky and very good brand (kingbo or amtech 559)

all ° are celsius.

for small bga chip put flux. if pcb is really cold it can teke even up to 120 seconds to remove it.

set max temperature to make chip lead melt, but not make chip burnt on top.

ive seen also all that yt video where they are able to remove ic veryt fast, but my hotair has fan and not pump, plus i prefer to not make ic too much hot fast... prefer more time but no damage. ofcourse after 120-180 seconds u should be able to remove it, otherwise or increase air flow or temperature by 10° step increase.
after chip is removed, for bga i clean wole pcb with solder iron flux and desolder wich first i apply some leade solder , then remove all with desolder wick by adding some more flux. clean all with ipa. apply some new flux when pcb is dry and solder back ic.
same tecnique when i can add some leaded solder (inductor resistor and so on. it require much less heating time for removing it.
check also hot air flow on board ... sometimes u heat straight and component starting melt are the one on top or bottom of air flow direction. check that and make some circle on ic , moving it with tweezer very gentle. when chip start move keep heating and after 10 seconds try remove it without making any power...

hope all that help.

[sam_sam_sam]

One thing that might help a lot is to use the correct tip to cover the ic chip and it’s pins and use enough air flow to keep the heating element from burning out the distance from the output of hot air gun also makes a difference as well