Anyone out there know of a decent lead free solder which flows as good as the tried and true 60/40 or 63/37 Kester stuff?
Its mostly for reflow work repairing old stuff, so it needs to wet and flow just as good without 900 degrees of heat. Most of the older audio stuff uses wave soldered and hand retouched PCBs. You want to keep the heat down to a minimum with those more fragile, older though hole components.
Its mostly for reflow work repairing old stuff, so it needs to wet and flow just as good without 900 degrees of heat. Most of the older audio stuff uses wave soldered and hand retouched PCBs. You want to keep the heat down to a minimum with those more fragile, older though hole components.
You need to use the same solder as is on the thing being repaired, or else completely remove the old solder and replace it with new, as mixing different kinds of solder will not give a eutectic and will be pasty and prone to dry-joints.
For hand soldering with lead-free you need to use SAC solder (SnAgCu, basically 3 or 4% silver, 0.5% copper and the rest is tin.) which is a eutectic and thus can be worked easily. Other types are for automated assembly really, they are horrible for rework.
SAC solder needs a somewhat higher temperature, which means it oxidizes faster and you have to be more pro-active with flux. Never leave an iron on unattended for long periods at these higher temperatures, the oxide that forms on the bit can become very persistent and hard to remove (and never use abrasives on a solder iron bit, they cut through the iron plating and render it useless).
[ incidentally 63/37 is the eutectic ratio for tin/lead, not 60/40 ]
For hand soldering with lead-free you need to use SAC solder (SnAgCu, basically 3 or 4% silver, 0.5% copper and the rest is tin.) which is a eutectic and thus can be worked easily. Other types are for automated assembly really, they are horrible for rework.
SAC solder needs a somewhat higher temperature, which means it oxidizes faster and you have to be more pro-active with flux. Never leave an iron on unattended for long periods at these higher temperatures, the oxide that forms on the bit can become very persistent and hard to remove (and never use abrasives on a solder iron bit, they cut through the iron plating and render it useless).
[ incidentally 63/37 is the eutectic ratio for tin/lead, not 60/40 ]
@akimmet I agree. Thats why I don't want to run it that high, but often times when you're working on a section of PCB with a larger area of copper (ground traces), you need a little overshoot temp to get things flowing.
The newer solder requires special flux and higher temps to begin with. I've never lifted any traces with high solder temps, but the flux deteriorates fast, smokes badly and spatters all over the place.
What some people don't get is sometimes you need more heat to solder.quickly and avoid stressing smaller components. This sounds counterproductive, but in actuality the faster you can solder, the less time the heat has to reach the component internals.
The extra copper they add to the newer solder requires higher temps. You can see the solder takes on a dull appearance once it cools down. It looks like a cold solder joint when it does this, so its hard to distinguish a properly executed connection if the solder composition is unknown. With newer gear, this adds to the issue and is problematic even if you remove the majority of existing solder before redoing the connection with 60/40. Thats really a massive waste of time.
The newer solder requires special flux and higher temps to begin with. I've never lifted any traces with high solder temps, but the flux deteriorates fast, smokes badly and spatters all over the place.
What some people don't get is sometimes you need more heat to solder.quickly and avoid stressing smaller components. This sounds counterproductive, but in actuality the faster you can solder, the less time the heat has to reach the component internals.
The extra copper they add to the newer solder requires higher temps. You can see the solder takes on a dull appearance once it cools down. It looks like a cold solder joint when it does this, so its hard to distinguish a properly executed connection if the solder composition is unknown. With newer gear, this adds to the issue and is problematic even if you remove the majority of existing solder before redoing the connection with 60/40. Thats really a massive waste of time.