I am working on a main board for a Samsung LCD TV. One of the polymer tantalum capacitors is bad and I am replacing it. I have removed the capacitor and am trying to clean up the contacts and remove the old solder. But the solder on the contacts doesn't seem to melt at all with the two soldering irons that I have (a 15W and 30W). The two soldering irons get hot and can melt solder wire just fine, but for some reason, the solder on this board won't melt at all with them. Do I need a special iron to remove the solder on this board?
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Re: Problem Cleaning / Removing Old Solder from Board
try adding flux and/or new solder -
Re: Problem Cleaning / Removing Old Solder from Board
Was it an SMD or a through-hole part?
How are you trying to remove the solder?
Photo?"Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
-David VanHornComment
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Re: Problem Cleaning / Removing Old Solder from Board
Add some fresh leaded solder then use some braid to remove the leaded/unleaded mix.
It's possible that you need a better iron if it's not melting with your 30W.Comment
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Re: Problem Cleaning / Removing Old Solder from Board
It is an SMD board.
At 1st, I was trying to use a copper desoldering braid, but I noticed that it didn't seem to be removing any of the solder. I then tried to melt the solder on the board directly with the soldering iron (and then apply the braid once it was softened), but it didn't melt at all. I applied the soldering iron directly to the solder for a few minutes and nothing happened at all. I then tested the soldering iron on two types of solder wire and it melted them fine. So I was wondering what type of solder they were using on the SMD board and if it required a higher temp (and different soldering iron than I have).
I cleaned the solder tips (with sandpaper), checked that the tips were securely tightened, tinned the tips, and tried again, but the solder still wouldn't melt.
I have attached a cropped photo of the board that shows the capacitor that I am replacing. The capacitor is outlined in red. The capacitor is very small. It measures about 3.4mm x 2.8mm. This photo was taken before I removed the capacitor. I don't have a more recent photo at this time. If I get a chance, I will try to take one later.Attached FilesLast edited by Tron82; 04-03-2017, 06:48 AM.Comment
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Re: Problem Cleaning / Removing Old Solder from Board
You should first clean the area with high % alcohol, then add flux and fresh solder. Those components are much easier to remove with a hot air station.
I have a hot air rework station, and whenever my iron is melting any solder too slowly, I blow the area with hot air around 240C. Everything solder joint my iron touches melts like butter. Perhaps you could use a blow dryer or heat gun(6 inches away on low) if the other suggestions fail. I would also recommend buying low melt solder so you can blend it with the old solder to lower the melting point.
Be careful with the airflow and temperature though so you don't burn anything or blow anything away.
Also, cleaning tips with sandpaper really not ideal. Copper wool would be better, and if you want to keep tips fresh then make sure to tin them with solder before storage to prevent oxidation.Last edited by Hellfiya; 04-03-2017, 12:30 PM.Comment
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Re: Problem Cleaning / Removing Old Solder from Board
These are easy to remove. Blast them with heat. Just get 50-60W iron. The problem is that perhaps these components are soldered with lead free solder. This means higher melting point and this means that you need more heat.
Week ago I've replaced the burned diodes inside a metal detector. Exactly the same situation. There were no problems with 60W soldering station.
You need hot air station if you are trying to remove/solder SMD part with more than 4 legs. ..Last edited by televizora; 04-03-2017, 02:18 PM.Useful conversions. I don't "speak" imperial. Please use metric, if you want to address me.
1km=1000m=100000cm, 1inch=2.54cm, 1mile=1609.344meters, 1ft=30.48cm 1gal(US)=3.785liters, 1lb=453grams, 1oz=28.34gramsComment
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