SMD rework tips

[pucho812]

Anyone got good rework tips for surface mount stuff. I know right tool for the job and I am quite good with my tweezers for removing resistors and caps.  But, I have a hard time with chips. I have  the necessary stuff like a air pencil and big enough tips so I can really get the air flowing but for soic-16 I  have the hardest trouble and having pulled pads  I must be doing something wrong. 

Anyone got some good tips/suggestions to share?

 

[joaquins]

Bodging a lot of solder on the pads so they are all soldered together, then you only need to flow two spots of solder. There is a special solder with low melting point for this job, if you get it you could probably do it with your first iron from older days. It last quite a bit fluid so you have time to heat both sides with a single big iron and remain fluid enough time so you can shake the board till the chip falls off. You could do it with conventional solder but the overheating may damage the board if you go too far.

JS

 

[JohnRoberts]

I am not sure if an air pencil is the same thing, but basically you get the chip and all the leads hot enough with hot air that all the solder is liquid and the chip just slides off the pads.  Absolutely no (or very little) force is involved.

I use a pair of tweezers for moving parts around.

JR

 

[pucho812]

well I have to hot air tools, one is a pencil as mentioned before the other is hot air station.  The hot air station  is what I am using for ic's Maybe I am just being impatient and not waiting long enough?  Maybe I have the wrong settings for temp and air flow speed?

 

 

[zayance]

There is a special solder with low melting point for this job, if you get it you could probably do it with your first iron from older days.

+1, it's called "Chipquick".
You add a sausage of flux, then melt this low melting point solder on all pins, and while heating all up, just lift the part away.
Use desoldering braid, and clean with izopropyl and you'll be good to go, with a nice clean area for resoldering.
Just have to make sure all that Chipquick is welle sucked out, so still needs some care not to overheat pads but....

Well that's the other option for if not having the hot tweezers..., that's great tool to have if you do a lot of SMD i think...
Specially the ones that allow a lot of different Tips shapes to be fitted on, The tips for SOIC 16 could be a little expensive, but that's always the case when starting to use "pro" equipment, but might find some budget ones, if you think you'll definitly need one????


T.

 

[pucho812]

tried this today and it worked great. I'm currently fixing a valley audio, valley people, etc 401 mic processor. It's all SMD outside of some electrolytics. Anyway I need to replace a  16 pin soic chip and an 8 pin soic. So I tried this today and it worked amazingly well. Since the pin's had enough spacing between I was able to clip the pin right at the IC using diagnal cutters/dykes. this in turn allowed me to remove the IC  with all the pins still  attached  to the pads. I then was able to treat each pad individually removing the pin and keeping it complete intact without being pulled off. It did take a  minimal amount of time longer to do but it did work well.

 

[sodderboy]

Sounds laborious!  Another +1 for the chipquick, flux lots of it, and also dental tools.

I've posted it before, but my best tip for the occasional SMD repairer is to get junk boards from a MI or TV repair place and practice.  You can remove/replace the same component a few times and then hit your patient with proper muscle memory.
Mike