soldering on circuit boards and decoders : LUSENET : Wiring for DCC : One Thread

What size soldering iron is recommended and is it advisable to wrap the board or decoder in a slightly damp cloth?

-- ken ison (, May 07, 2004


25-35 W soldering iron. I prefer to use a hotter iron like a 35W unit, but you need to be a good solderer. You need to make the joint and get off the board. A 25 W iron you will find will be good for small circuit board work, but whenever you need to solder something big, you may find that it is not hot enough. By big I mean soldering something like a wire to a connector.

Don't worry about trying to wrap your work with a damp cloth. To reduce overheating the board, the best thing is to make sure the circuit board is clean and your soldering iron tip tinned. Pre-tin wires if you are attaching a wire. Apply your heat, quickly make your connection, and get off the board.

-- Allan Gartner (, May 08, 2004.

Thanks for the advice Allen

-- ken ison (, May 08, 2004.

I've soldered to NASA-level specs (requiring yearly re- certification) for over twenty years, so I've picked up a number of useful tricks (and made plenty of mistakes!) along the way. An alligator clip makes a fine heat sink to conduct heat away from an area you would prefer to keep cool, whether it's a transistor leg or track rail. (A damp paper towel works well too!) Of course, the best advice to minimize dwell (applied heat) time on the two surfaces being soldered by physically joining the soldered components, whether its two wires placed side by side, (lap soldering) inserting a chip in a board and taping (no Scotch tape, its an ESD generator!) it on the chip side to keep it pressed into the board, etc. Properly postioned components allows the solderer to add flux, then heat and solder to ensure a high-quality, strong joint with minimal resistance. Excessive solder is almost as bad as too little. The right amount should fill all voids and leave a smooth, shiny finish (on pads, for instance). For splicing wires, I place the stripped and tinned areas side by side and flow just enough solder to still be able to see the outline of the wire. No peaks, blobs or solder balls should remain. Disturbed joints (caused by movement during cooling) are indicated by wavy lines in the joint. Inadequate flux (preventing solder flow) will leave pits and holes. Remove the flux with isopropyl alchohol or a good flux solvent as soon as possible after soldering. The longer it sits on the joint, the harder it gets and makes removal more time- consuming. Always tin wires to be soldered. Chips can be tinned, but since these aren't going to the moon its not necessary. Do inspect the joints under a magnifier or jewelers loupe if you can. Broken strands of conductor, melted or burned insulation is not good. The best wire to use is teflon jacketed. Its more expensive than regular wire, but the insulation never creeps back when you apply heat. Look on eBay for deals on spools of teflon wire. Sorry to ramble so, but good soldering needn't be hard. You just have to be consistent. Practice before you start the real deal. Feel free to email me with any questions regarding your situation or application. If it needs to be soldered, I've probably done it at some point!

CC Clarke

-- CC Clarke (, October 10, 2004.

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