Working with SMD. How to do it without specialised tools. - diyAudio
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Old 11th August 2008, 10:55 AM   #1
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Default Working with SMD. How to do it without specialised tools.

Something I have been meaning to do, put down in words and pictures how to work with surface mount components. This is a technique I developed years ago when SMD first appeared and we hadn't the luxury of re-work stations etc.
These pictures show how to remove a "postage stamp" I/C. Timewise it would take me around 6 or 7 minutes to remove.
First picture shows the tools used. Nothing special, just a good iron and braid and a jewellers screwdriver that fit well between the legs of the IC.
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Old 11th August 2008, 10:58 AM   #2
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This shows how to apply the braid. Use a hot iron, I used a large tip as you will see, and don't be afraid to even "apply" a little fresh solder to help it wick up into the braid. You will never "unsolder" the legs this way, just quickly remove excess solder.
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Old 11th August 2008, 11:00 AM   #3
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Using the jewellers screwdriver. Carefully ( I fitted a smaller tip in the iron for this) heat the print directly in front of the first leg and at the same time with the driver between this leg and the adjoining lever gently to "break" the bond. Do this for all the legs-- takes minutes thats all.
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Old 11th August 2008, 11:03 AM   #4
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Here is the removed IC. It's good enough to re use. Now that is something you should never do but I will, just to show how to fit an SMD device.
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Old 11th August 2008, 11:06 AM   #5
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This is the "unprepared" print. Using braid "wrapped" over the iron tip gently wipe the print ( never crossways - it WILL lift and be damaged) and remove all excess solder. Clean with ISO if required.
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Old 11th August 2008, 11:08 AM   #6
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Position the new IC. Make sure it is correctly positioned. You can either try and solder each leg by applying solder to the print directly in front or try this. Put plenty on, then use the braid as earlier to remove.
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Old 11th August 2008, 11:12 AM   #7
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Job done. Remember this was a re used IC and the pins were not perfectly straight. In reality it looks pretty good, and a new part should be virtually idestinguisable from a factory fit.
So if you are wondering how to get that OpAmp out. Now you know
I should add that a lot of parts are glued as well. No problem. Just be 100% sure ALL the legs are free and either prise off or "grip" with pliers and twist.
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Old 18th August 2008, 07:40 AM   #8
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Nobody ever wondered how to work on SMD without the proper gear.
Actually I had nearly forgotten about this thread so thought I would bump it back so it doesn't fall off the end of the world. It was either that or go for the most number of views without a reponse
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Old 20th August 2008, 05:58 PM   #9
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Thanks for sharing.
Removing SMT devices is certainly a challenge.
Other techniques that have worked for me is the use of a hot air gun instead of a solder tip. The risk of damage is lower. The problem is that you can blow off a small chip cap if one is not careful!!

The components are becoming smaller and smaller, and my vision keeps getting worse and worse.
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Old 21st August 2008, 07:15 AM   #10
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Hi Fernando,
I think a lot comes down to what you are most comfortable with, and what works for you. Never tried the hot air gun.
I remember whan we got the new PACE rework station, and all the attachments Never seen so many ruined PCB's. Guy's would heat an I/C with the special bit's fitting all round the chip ( you could smell the board frying ) then "twist and hope" usually with all the print coming off. Horrendous.
The worst thing I find is plated through via's.
All good fun
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