Author Topic: Rework Exposed pads  (Read 925 times)

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Offline RBeaubien

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Rework Exposed pads
« on: November 18, 2016, 04:21:07 am »
Ok, I'm hoping there is a trick to this.  How do you remove SMD chips with exposed pads (like the MP1584EN or the MAX7456-EP)?  I have boards with defective chips and when I try to remove the chips, I end up having all the other components around them come off BEFORE I can heat the chip up enough for the exposed pad to release.  I'm talking 4-5 minutes here at 750°F.  Any guidance would be appreciated.
- Robert Beaubien
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Offline rigrunner

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Re: Rework Exposed pads
« Reply #1 on: November 18, 2016, 05:22:24 am »
Hopefully this will help?

If the board is densely populated I use the smallest nozzle  i have and around 360-380C/680-716F. Circle the IC about 2.5cm away.
If that fails i run a fine wire under the legs on one side of the IC and user an iron to melt the solder as i gently pull the wire up, lifting the pins as it goes.
If that fails, and it rarely does, i cut the legs from the IC package with a scalpel and remove the remains with an iron.

RR
 

Offline wasyoungonce

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Re: Rework Exposed pads
« Reply #2 on: November 18, 2016, 05:51:33 am »
These chips are both SMD TSSOP or SOIC.......Use Chip Quik and an iron or with a heat gun.  I found using a iron works well!

http://www.chipquik.com/store/
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Offline Rasz

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Re: Rework Exposed pads
« Reply #3 on: November 19, 2016, 05:06:25 pm »
preheat the pcb?
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