how long does it take for a short to damage a circuit board?

[dinodoody]

I tryed reballing a GPU for the firs time today. I used hot air to take off the chip and then replace the balls on it. But when I put the chip back on I think the board was warped a little bit and some of the balls got bridged (shorted). I turn on the computer for only 3 seconds and i felt near the chip get really hot so I turn it off. Is 3 seconds enough to ruin things or did i shut it off at the right moment.

[MatCat]

I tryed reballing a GPU for the firs time today. I used hot air to take off the chip and then replace the balls on it. But when I put the chip back on I think the board was warped a little bit and some of the balls got bridged (shorted). I turn on the computer for only 3 seconds and i felt near the chip get really hot so I turn it off. Is 3 seconds enough to ruin things or did i shut it off at the right moment.

I have had chips do this and be fine, and others that where not... the only way to know is fix it and test agan.

[dinodoody]

This is good to know. I will try again another night, not right now because I am sick of the fumes. I need to use a fan or something and open a window next time.

[Neilm]

Did it have a heat sink on it before you removed the chip? If so did it have the heat sink on when you powered it up? I killed a processor a few years ago by forgetting the heat sink - it was on for about 5 seconds.

[T3sl4co1l]

Depends on what gets shorted.  Power to ground?  Maybe the power supply is current limited, maybe it's bricked.  Power to power -- the wrong way?  Probably burned a hole in the substrate.  Power backwards into a signal pin?  Probably vaporized the pin structure.

As for "how long"?  A couple microseconds and up.  Consider that a switch can be flipped on and off in about 20,000 times longer...

Tim

[dinodoody]

did it have the heat sink on when you powered it up? I killed a processor a few years ago by forgetting the heat sink - it was on for about 5 seconds.

I had the heatsink on. I'll keep you guys updated and report back if it works or not. This time I figured a way to keep the board from warping, i bolted it down to the preheater with about 1 inch standoff (last time it was just sitting on pieces of hershy-kiss-shaped tinfoil)

[JuKu]

How long does it take for a short to damage a circuit board? Anything from a few nanoseconds to several years. In other words, no way to know. But a chip that has heated over spec is not as reliable as it could be anymore. It might work very long, but if reliability is a concern, be concerned.