Getting set up to try my hand at fixing the daughter's iPad; going to practice on some scrap boards first.
Finally found a good use for that Cr1pt0r-prone D-Link DNS-320 NAS; MB has lots of BGA for me to practice on.
A smartphone sticky-pad seems to work well at holding the workpiece right where I put it; I borrowed my daughter's Unicorn Snot play putty to hold the thermometer in place. This should give me some crude process control for preheating the MB and terminal temperature monitoring.
I've done a fair bit of hot-air rework replacing FETs and STM32s on FCs and ESCs, but it has been easily 2 years since my last. This station is new to me, so I need to get used to how it heats up and responds with different nozzles, etc. Also, I'm just a bit leery after the prelim prep work on the iPud MB.
mnem
tssssst...
Preheating seemed to hit the entropic wall at aboot 150°C with the 8mm nozzle set at 380°C; it just wouldn't go any higher. Bumped set temp up to 410°C and started heating the chip; less than 30 seconds and it floated at aboot 180°C on the thermo.
Here the pads have been retinned with lead-bearing solder as is usual practice found in numerous iPwn repair vids; with a little care you can usually get "just the right dome" to be able to just plop & reflow the new chip with some fresh flux. I wanted to practice this method beforehand; however unlike the 1610A3 this is a stepped package chip, so requires the complete prep of desoldering both sides and reballing.
That, however, is not my biggest hurdle right now; board density is. This board is an order of magnitude more miniaturized than my practice PCB. To give you an idea: that chip is 2.1mm
2, and there is a 6x6 grid of pads under it.
I just plain can't see it clearly unless I use
both my magnifying visor and the magnifying lamp located right over the work. Trying to do it from an angle just distorts everything to illegibility. The focal length of this combination puts the lens of the lamp 50-60mm directly above the work, and there simply is not any way to get the hot air nozzle anywhere near the chip.
I guess I'm gonna have to start shopping a cheap digital microscope; either that or swallow my tinkerer pride and send the board off to someone who's better equipped.
mnem
Murphy's a bitch, and she has puppies.