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Underfilled BGA Removal

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#71880

Underfilled BGA Removal | 27 March, 2014

My company is researching the use of re-workable underfill for use on our avionics boards. We are currently testing Hysol UF3810. The Rework machine we use has a vacuum based removal system witch isn't strong enough to overcome the underfill. We have looked at twisting the parts but on some of the chips there is not enough room to do this. Can anyone suggest any other methods for removal?

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#71882

Underfilled BGA Removal | 27 March, 2014

If you are 100% sure that the solder has reflowed (time and temp based), then just use an wood stick to wedge the part upwards. It just takes a little bit of "lift".

I used a wooden Q-Tip end that I trimmed to a wedge using an exacto blade. Wait for reflow, slide beneath one edge and twist. Voila!

Of course if your solder has not actually reflowed, you will lift pads from the board using this method.

Best of luck. Shouldn't be that hard to figure something out. 'hege

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#71887

Underfilled BGA Removal | 28 March, 2014

hege: beer can opener!!! The ultimate multipurpose tool ...

BR davef

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#71888

Underfilled BGA Removal | 28 March, 2014

With heat, most underfills soften just before the solder melts. So, keep poking the underfill until you see it soften. Then, wait just the correct amount of time until the solder melts and quickly snap or torque the part from the board.

BR davef

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#71889

Underfilled BGA Removal | 28 March, 2014

Lol Dave.

Give me a lever long enough....

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#74621

Underfilled BGA Removal | 28 September, 2015

Hi, sorry for reopening a old thread, but i wanted to ask if there is a way to know at what temperature the solder melts if you have a chip with underfill? I thnk its lower then normal air-fill temperature since the underfill conducts heat better then air. The reason i ask is that a lot of problems dont need chips replacement just rework, and in some cases a good reflow will do the job just right. The problem is that when you heat a underfill chip to much the solder tends to boil and come out of the sides causing shorts and other problems. So its ideal to set the rework station at exact the reflow temp.

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#74625

Underfilled BGA Removal | 28 September, 2015

The melting point of the solder itself does not change when you have underfill. If the underfill conducts heat better than air, it will take less heat (and/or less time) from your rework station to get the solder up to the melting point. That makes it appear that the solder melted at a lower temp but it didn't.

What you are really asking is what is the difference between a rework profile (heat + time) of a BGA when it does not have underfill (air only) and when it does have underfill. Since that will depend on what underfill is used, the only way to answer that question may be trial and error.

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