ASUS P4P800 SE rev2.0

On this mobo there was shorcut on USB-s to null. I wanted to change ICH5. When I took off this burned Southbridge, I found that one of the footers (I don`t know how to say on russian- place on mobo under BGA chips where balls are soldered) is missing. It felt down with ICH5...
Its R20.
It`s quite often to find one or more footers missing when bridge is taken of. What to do when souch situation is present? Can they be restored somehow? Can mobo work without this R20 (according to datasheet its HI7)?

P.S. If this subject is more propriate in technology section please send it there.

Аватар пользователя ADEPT707

R20 is connected to the point between p19-p20-r19-r20 on this mobo
use thin copper wire and pb-free solder to restore this footer, than mount ich-5 with pb solder

Аватар пользователя Root

1) Firstly, you _must_ improve your technology of reworking BGA chips (soldering/desoldering). Because it isn't common problem of desktop motherboards.
2) Lets look at ICH5 DS. Yo can find there that R20 is 'VRMPWRGD' signal. It is not good idea let this signal be not connected.
3) One can restore footers on motherboard. It is difficult. In fact, now I'm only learning to do it. Idea is that: you look what wires were connected with missing footer and with lead-free solder & thin wire (like 'жила МГТФ') make new footer.

Аццкий ромбовод {:€
Я пока не волшебник - я только учусь! :-P

Jega писал(-а):
I don`t know how to say on russian- place on mobo under BGA chips where balls are soldered
"Контактная площадка" - official, "пятачок"/"пятак" - slang.

Here you can read about repairing footers.

Jega писал(-а):
Can mobo work without this R20 (according to datasheet its HI7)?
HI7 - on M20:). On R20 - VRMPWRGD. Both signal is needed for mobo functionality.

Аватар пользователя Jega

Thank you gentleman for prompt answer.
You were right about asignment for R20 pin. I was watching ICH4 datasheet instead ICH5:( sorry...
I have this problem with taking of footers only on ASUS mobos.On Gigabyte, MSI etc. I don`t have that problem.
Is temperature to high or to low that is producing that effect? Maybe heating time must be longer? Shorter?
I`m heating chips with lower temperature and rise it gently through time until chip start "swiming". Then I wait for moment and take him of as author of "Замена южных мостов ICH5" in WIKI suggested.

Аватар пользователя Jega

I want to share with members what was problem with broking footers on mobos I was taking of bridges:
Lower temperature was to high. In order to take of bridge as soon is posible from reciver mobo (bridge is already dead so I thought he can`t die again:) I put temperaure almost 350 degrees for lower heater (measured with temperature sonde). How stupid of me!!!
Result was many broken footers on many mobos.


Right way is to put lower temperature for lower heater (on my experiments for lead free solder about 200-220 degrees) and use uper heating (I use AOUE 857A++) on 310 degrees. I found that lowest temperature to melt lead free solder with my heater is 310 degrees (acording to heater digital display). Of course, temperature on bridge is not 310 degrees but much less when heated air fall to it. Bridge is heating realy on 180-210 degrees (measured with temperature sonde).
Result is quick taking of bridges without footer defects. Also, bridges from donors wont die during procedure and balls with motly wil be on place so realling is not neaded.

Root, you were right about my technology of solder/desolder chips. Thank`s

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