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I want to practice reballing of IC on iPhone logic boards. I bough several iPhone 4S boards ver cheaply, but I have run into trouble: the components are covered with brown coating that prohibits access to the individual elements.
The coating is very hard and so far I have failed to remove it with my precision knife. What is the trick?
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@lacek that stuff is the underfill. A PITA to remove. I use some heat ~120deg C and a dental pick when I have to remove it. Check on something like this for an idea.
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this one actually peels off. Mine is almost rock-solid. I have also seen this one:
https://www.youtube.com/watch?v=FUKJaf02...
and again it seems more rubbery. I Did before an iPhone 5S and there it was way easier too. Does this underfill harden after a few years?
On iPhone 5S when I try to pierce that with say tweezers, they actually penetrate the underfill even if it is cold. Here I have to use excessive force just to leave a mark.
@lacek post some images of what you are working on right now. Use this guide Voeg afbeeldingen toe aan een bestaande vraag for that. Underfill is pretty rock solid and like I mentioned before I use heat and a dental pick to remove it. Not an easy task and it does take plenty of time....
I do not have a camera compatible with the microscope. I will continue this thread, but I have to get the camera first.
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