Reflowing: Now this is what I do. When I receive a board, I first
plug in the power adapter and plug in my post code checker in the mini-
pci slot (where the wireless card usually is.) Usually the board
turns on and right off, or it turns on and just sits. On the post
code checker if the board stays on, I usually get 4 digits on the
bottom but nothing for the top 2...usually means the gpu is shorted/
bridged spheres. Next, I turn on my hotair rework unit, put it to
180c, and use a little curved pick I made that is flat on the top and
bottom and about 1mm wide. This I use to remove the red epoxy. Once
removed I put some alcohol around the chip and clean it good with a
brush to help remove any epoxy under the lip. Then blow under the
chip with compress air to help clean out any debris. Add a non-
cleaning liquid flux and while holding the board vertically I add it
so it flows under the chip. Mount the board on my Honton bga rework
station (making sure it's flat and level) and run my reflow profile.
Basically heating the chip up to the 220-230c mark and then gently tap
the chip to make sure it's "floating" on the solder spheres and they
are in thier liquidous state. Turn the heat off and the fan kicks on
to help cool the board. After a couple minutes and the board has
cooled I then plug the cpu and memory back onto the board and power it
up. I would say 8 times out of 10 this will result in a good working
board.
)
