[stashtrey]

I've got everything I need to replace my MOSFETS that went bad but cannot get the old chips off the board. I've been using the hot air from my new station I bought. Running about 320 Celsius with no luck. I laid down a little solder paste on the prongs and got those loose but totally unsuccessful at even getting the chip to budge. Running heat front and back with no luck.

I'm hoping someone on here can chime in and tell me what I'm doing wrong...or share how you did it with hot air. It's the pad underneath that I can't get free. Worried about damaging the board or nearby components.

Any help is greatly appreciated. I know quite a few on here have successfully done this and hope to avoid taking it to a shop even though it will probably be easier. I bought all this shit thinking I'd knock it out and frustrated if I'm out all that money + paying someone else!!

Thanks so much!!

[vtl]

Originally Posted by stashtrey

I've got everything I need to replace my MOSFETS that went bad but cannot get the old chips off the board. I've been using the hot air from my new station I bought. Running about 320 Celsius with no luck. I laid down a little solder paste on the prongs and got those loose but totally unsuccessful at even getting the chip to budge. Running heat front and back with no luck.

I'm hoping someone on here can chime in and tell me what I'm doing wrong...or share how you did it with hot air. It's the pad underneath that I can't get free. Worried about damaging the board or nearby components.

Any help is greatly appreciated. I know quite a few on here have successfully done this and hope to avoid taking it to a shop even though it will probably be easier. I bought all this shit thinking I'd knock it out and frustrated if I'm out all that money + paying someone else!!

Thanks so much!!

320 is waay to low. 380-400 is more what you need for big surface mount transistors for most hot air stations. You can also shield the surrounding components from heat with Kapton tape

[Stroker1]

Rosin flux laid around perimeter of chip will aid in heat transfer. Short of that lay a small bead of solder paste around perimeter of chip and heat. My work station has a selection of different size shrouds which surround the chip, open at the top. This concentrates heat on chip you are removing. One could easily be made from some thin aluminum sheet. Be ready with tweezers so you can lift it when the ground plane under chip flows. Good luck.

[stashtrey]

You guys are frigging awesome!!! Thank you so much for thr quick replies and advice.!!!

Will report back.

[WedgePerformance]

You should also cut the legs off and pull them before pull the chip. Be careful and don't pull too hard. I use an iron to heat mine and a little solder around the back edge and they come right off with little effort.

[V8bait]

Use some flux, otherwise I'm not sure the issue. Use the correct hot air tip (medium circle or a square) and keep it close to the chip, move it around the chip to focus heat on it and not surrounding components, chip comes right off. The station needs to be set pretty high, or you need to hold the air gun closer.

Sometimes pre heating the board helps, but that may be more advanced.

[bimmertt]

I thought this would be way easier. I practiced on an old graphics card and was able to remove chips easily at 325. I can't get a single mosfet to budge even at 425. Been at it off and on for around 45 minutes. I'm thinking about throwing in the towel and going with the msd81 upgrade. Tried using no clean flux paste and still no luck. Shocked at how hard this actually is.

[vtl]

If hot air isnt working (may be a cheap station) may be worth trying a soldering iron instead.

If you have a decent soldering station with a decently large tip (4-5mm or so) you can blob some solder on the MOSFET legs and heatsink tab, then heat up the legs and tab, alternating between the two until theyre molten, then alternate some more and pick it out with a pair of tweezers. I prefer using this method since I've got a nice soldering station and its faster than using hot air.