EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: Quantumplate on July 08, 2023, 02:09:27 pm
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Well, this is a problem..
Removed the old ic by carefully snipping close to the body on one side of the chip. Then i simply flexed the chip using the other side's legs as a hinge until they snap - again close to the body so as not to dislodge the pads. Next i took my iron tip and removed all the leg remnants on both sides. On the side i flexed i have all the pads still nicely tinned, but on the side i sbipped, most of the pads are now bare, and despite copious flux and soldering attempts i can't tin any of those pads. You can kind of see in the photo, although it's a bit fuzzy.
Never had to deal with a blue pcb module board before. What's the deal as they say?
I'm using standard lead solder.
Thanks
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I should add the bare pads are not the copper colour - they are grey. Conductive but not sure of the material.
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A better picture would be good!
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The white edge and SIP header make me wonder if this is a ceramic substrate module?
If so, the shockwave from snipping the pins may well have cracked the actual pads loose from the PCB, and whatever's left there isn't a solderable metal - it may even be a printed carbon layer used to allow the pads and traces to be selectively built up by electroplating.
Incidentally some types of ceramic substrate module use screen-printed silver ink traces and pads, and it is then fired to fuse the silver to the ceramic surface, burn out the binder and sinter the silver particles leaving a continuous silver layer. Unfortunately this thin silver layer dissolves very quickly in ordinary solder, so you can't solder it unless you use an alloy contain several percent silver to slow down the rate it dissolves additional silver at, greatly reducing its tendency to eat the pads!
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Fabulous info thanks a lot!
I think you're right on the ceramic and the shockwave hypothesis. Boy am i stuffed now. I may be able to solder the side with the intact pads, but the other...i need some kind of tiny clamp, at least i don't see any other way. I can only laugh after spending a hundred hours on this unit!
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A better picture would be good!
I know. Best my tablet will afford.
So i think after research some silver conductive glue could make this repair. But which one...do you happen to know the best type for ic work?
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Move the tablet closer or further away until the image is in focus. A tripod also helps. Or take several shots until one comes out clear.
A better picture would be good!
I know. Best my tablet will afford.
So i think after research some silver conductive glue could make this repair. But which one...do you happen to know the best type for ic work?