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Best solder to use

Chris Riddell

Feb 12, 2015
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Hey guys,

Whats the nicest solder to use, I currently only have a cheaper soldering iron with no temp control and I'm soldering up circuit boards on copper board. I brought some from electronic store here the other day and it seems a tad thick and takes ages to heat up while the result is far too much solder on the board.

Thanks
 

duke37

Jan 9, 2011
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There are many kinds of solder. The traditional composition for electronics was 60% tin and 40% lead, often shown as 60/40. The traditional composition for plumbing was 60% lead and 40% tin so confusion could easily occur. Plumbers' solder is not suitable because it freezes over a range of temperatures.

If your solder was bought recently it will probably be lead free, mostly tin with some silver and copper. It will have a higher melting point than 60Sn/40Pb so will need a more enthusiastic soldering iron. If you are not too worried about a very small amount of lead getting into the environment, then go back to the original solder, it is still available. Do not handle the solder and wash your hands well before eating your jam butty.
 

Gryd3

Jun 25, 2014
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Hey guys,

Whats the nicest solder to use, I currently only have a cheaper soldering iron with no temp control and I'm soldering up circuit boards on copper board. I brought some from electronic store here the other day and it seems a tad thick and takes ages to heat up while the result is far too much solder on the board.

Thanks
This could also be due to your current soldering technique.
Share with us any markings on your solder and we can get a better idea... also the rating of your iron.
Typically the soldering iron is tinned with a little solder which should melt very quickly once touched directly to the tip. The iron is then placed with as much surface area as possible on the pad and pin of the joint you with to solder.
A second later, you touch the solder to the joint/iron tip and the solder should melt and flow into the joint.
That's my step, perhaps others can expand on that.
 

(*steve*)

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A lead based solder is the easiest to use and unless you really can't use lead I would recommend people learn to solder with it first.

Beware that cheap solder can be hard to use. It's probably fur to it not being what it says it is (I'm looking at you China). Get a good name brand. It won't be cheap but you'll thank me for it anyway.

Next, it actually makes a difference hire clean your solder is. Get a pen eraser, slice it part way through, slide ste solder into the slice and run it up and down the solder a few times. I don't do this ask the time but it really does make a difference.

The same sliced eraser should be used to clean the leads of components and the eraser can also be used to clean the board.

The previous steps remove much of the oxidization from your materials. The oxides both make soldering harder and contribute to the muck you sometimes see around a joint.

Most important is the condition of your tip. It should be clean and shiny and not have too much solder on it. A good quality tip will make a huge difference. Cleaning the tip on a damp sponge is Ok, but the brass swarf pads are heaps better.

Having a hot enough iron without it being too hot and technique to heat the joint properly before properly applying the correct amount of solder conclude the job.

The last part is the most important. I demonstrate to people that with the correct technique you can successfully use a non temperature controlled 80W soldering iron with 3mm solder and a 4mm tip to hand solder SOT-23 devices. I only do that to demonstrate that good technique is more important than your tools but while you develop your technique you can use the tricks above to make soldering a lot easier.
 

hevans1944

Hop - AC8NS
Jun 21, 2012
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Solder comes in a bewildering array of sizes and alloys. To learn more about it visit this Wikipedia page.

For electronics use, I prefer a eutectic 63% Sn and 37% Pb alloy with a rosin flux core. My favorite is Kester 44, which is also available in SAC305 lead-free alloy, 96.5% Sn, 3.0% Ag, 0.5% Cu.

As @duke37 mentioned, the lead-free alloys (there are several) melt at higher temperatures than lead-tin alloys. The eutectic 63/37 alloy has the lowest melting point and the narrowest solidus range. It quickly transitions from molten to solid while cooling, passing only briefly (if at all) through that "mushy" stage common to other alloys. 60/40 is probably more common and is almost eutectic. As for solder diameter, that will depend on what you are soldering. A good compromise for circuit board work is 0.035 to 0.040 inch diameter. Smaller diameters for surface mount devices (SMD) and larger diameters for components like electrical switches, fuse holders, tube sockets, etc. may be more appropriate. One old trick, if the diameter you happen to have on hand is too large, is to flatten the end with long-nose pliers. This presents a smaller mass of solder to melt and may work in a pinch as a substitute for smaller diameter solder.

If you plan to do a lot of electronics hobby work, buy a one pound spool of either 60/40 or 63/37 alloy in 0.031 to 0.040 inch diameter with a rosin core. This spool will likely last you for a lifetime of soldering. I still have a small spool (about a 1/4 pound left) of 0.035" diameter eutectic alloy that I purchased more than thirty years ago. And sometime in the last century I found a "bargain basement" lot of one pound spools of 0.040" diameter 60/40 alloy Kester 44 for around $6.00 per spool. So I purchased five of them... and gave all but one away. The cost of rosin cored solder is today close to $30.00 per pound, but still a bargain, IMO, considering how long a spool will last. Be sure to purchase a "name brand" from a reliable distributor. Amazon is a good place to start looking.

As for soldering irons... I have used a now-obsolete Weller WTCPN soldering station for more than thirty years for circuit board work. It accepts various shaped tips (conical, spade, etc.) each with a temperature sensitive switch (opens when Curie temperature is reached) that regulates the tip body temperature. Actual temperature at the tip will depend on the mass of the tip and how much heat is "sucked away" when the tip is applied to make a soldered joint. You can buy more expensive stations with more sophisticated temperature control, which may be useful if the higher melting point lead-free alloys are used, but I haven't found that necessary yet. You can also buy very inexpensive soldering "pencils" but ultimately you buy what works for you. Most soldering pencils in the range of 40 to 60 watts will provide satisfactory performance. Expect to replace tips every few months or so as solder will ultimately dissolve the tip. You must keep the tip well-tinned with solder to make satisfactory solder joints.
 

BGB

Nov 30, 2014
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my experiences:
60/40 SnPb (Tin/Lead) solder: good for soldering electronics.

SnAg (Tin/Silver) solder: works if one doesn't have anything else, hassle to use, doesn't wet well, kind of makes a mess. I have a few boards mostly soldered using this stuff.

in general though, I much prefer 60/40 Sn/Pb for soldering circuit boards and similar.


for a while, I was using a 45W iron, which was pretty good... but then it broke (mostly stopped getting hot...).

I had been using another 25W iron, but this is more annoying. it takes a long time to get hot and solder things, and touching anything "heavy" (such as thick wire) can cause it to lose temperature and get stuck (as the solder solidifies).

I have a newer/nicer 35W iron, but I have it in my bag and mostly use it when off places and a need arises to solder something (also duct tape, a glue gun, ... can be pretty useful as well).

all my irons are fixed rating.


I had used soldering stations before (elsewhere), but for a lot of this stuff, had been doing quick/dirty stuff like sticking things together or tinning wires, so had used them at full power (IIRC, 80W or something). but, even something like this has a hard-time reasonably quickly tinning an 8AWG or 10AWG wire, so one ends up essentially mostly tinning parts of the wire at a time, and dealing with the issue that heat likes traveling a fair distance down such a wire (like, try to tin an 8AWG and a good several feet or so of the wire gets hot, *...), but not nearly so readily across the wire (one trick is to try to twist it tight and tin a ring around the wire, which makes heat flow better to the rest of it, making the rest a little easier to tin).

this is mostly because IME, when tinning wires, it seems best if it gets really hot really fast, so that the solder flows right on. but, sadly, this isn't really doable with thick wires.

*: these were basically the power wires for brushed DC motors roughly about the size of 1lb coffee cans.

they were being tinned mostly as this made them work a bit better with the type of clamp-down terminals being used.
 

hevans1944

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Jun 21, 2012
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For tinning wires, nothing beats an old fashioned solder pot. Here the admonition not to use flux does not apply. I always kept a tin of non-corrosive resin flux handy to keep the molten solder clean, to dip the ends of the wire into before dipping into the solder pot, and removing the dross as necessary with a wooden Popsicle stick or similar high-tech tool. Hardly worth the effort to heat up the pot if you have just a few wires to tin, in which case you need a hefty bench iron, maybe 200 watts or so, to get the job done quickly without wicking the heat up several inches and possibly melting the insulation. I now prefer a properly crimped connection for stranded wires, but that doesn't work so well on solid wires without a ferrule, two or more solid wires, and a star crimping tool. For really large-gauge connections, like on electrical panels, a properly selected compression fitting works well. Soldered connections are only good where there is almost zero mechanical stress on the wire. Welded connections are strong and permanent, but I doubt the average hobbyist has the equipment or the know-how to make one.
 

BGB

Nov 30, 2014
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For tinning wires, nothing beats an old fashioned solder pot. Here the admonition not to use flux does not apply. I always kept a tin of non-corrosive resin flux handy to keep the molten solder clean, to dip the ends of the wire into before dipping into the solder pot, and removing the dross as necessary with a wooden Popsicle stick or similar high-tech tool. Hardly worth the effort to heat up the pot if you have just a few wires to tin, in which case you need a hefty bench iron, maybe 200 watts or so, to get the job done quickly without wicking the heat up several inches and possibly melting the insulation. I now prefer a properly crimped connection for stranded wires, but that doesn't work so well on solid wires without a ferrule, two or more solid wires, and a star crimping tool. For really large-gauge connections, like on electrical panels, a properly selected compression fitting works well. Soldered connections are only good where there is almost zero mechanical stress on the wire. Welded connections are strong and permanent, but I doubt the average hobbyist has the equipment or the know-how to make one.

I like to crimp and then solder, as the soldering basically makes sure the crimp doesn't come off (say, if the wire is pulled on or similar), but sadly doesn't work well for very small connectors (where basically the solder may flow into and fill up the connector).

for the heavy wires, the type of connector used on one end was a sort of spring-loaded terminal, where basically you would stick a flat-blade screwdriver in between two metal bars and use it as a lever, which opens up the port for sticking the wire into (which sort of resembles the inside of pliers), and when releasing force on the screwdriver, it basically clamps down on and holds the wire. without tinning, the wires liked to fray and come apart, but if tinned they held pretty solid.

another type of terminal involves using a screwdriver to turn a screw which tightens down on the wire. I prefer this style of terminal more (vs the spring-loaded variety).


the other end of the wires had fork connectors crimped on and soldered, which were held in place using screws. meanwhile some of the heavier wiring on the thing (4 AWG) was generally attached using hex-bolts and nuts through ring connectors (didn't try tinning any of these wires though).

I am guessing probably a butane torch and plumbing solder would be more effective for soldering and tinning 4 AWG and 1/0 AWG and similar though (like, maybe put flux on it and use a torch and tin it more like it was a pipe or similar). doesn't seem like it would be worthwhile trying to do it with an iron.

solder pot, maybe this could also work...
 

davelectronic

Dec 13, 2010
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I made the transition over to lead free and had issues with the lower silver content stuff, I moved on to the more expensive higher silver content stuff and its fine, but its expensive stuff, and I've stuck with maplins as a source, its buried at the bottom of my tool box after moving recently, but its maplins highest silver content solder.
 

David Moore

Aug 25, 2017
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I've started up again after 15 years, and was failing to even tin my iron or tin a wire, complete disaster. Thought I was being good by using lead-free, however I found some 30 year old leaded solder, and now seen the difference.

Problem is, what to do with 200g of lead free?
 

duke37

Jan 9, 2011
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"Problem is, what to do with 200g of lead free?"

Use it to solder your water pipes.
 

davenn

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I've started up again after 15 years, and was failing to even tin my iron or tin a wire, complete disaster. Thought I was being good by using lead-free, however I found some 30 year old leaded solder, and now seen the difference.

Problem is, what to do with 200g of lead free?


you do realise that lead-free solder requires a higher temperature ?
 

David Moore

Aug 25, 2017
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I had it up at 450 deg c. I managed to melt the plastic casing of some equipment before the solder would melt. This was totally not a problem with lead solder, and I was able to go down to 350.

I also had a constantly blackend iron tip when using lead free. It just doesn't seem to work for me.

Perhaps more expensive 4% silver would be better, but I still have these two rolls left over.
 

(*steve*)

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There are a plethora of lead free solders in the world. If you're using lead free solder you really need to know what it's made of and what its characteristics are.

It may be as simple as it having a higher melting point, looking a little dull, and being more brittle. But there are some that I swear you almost need a blowtorch for.
 

kellys_eye

Jun 25, 2010
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I'm often tempted to stock up for the eventual occasion when even leaded solder is made 'illegal' for amateur use..... it can't be too far off although how they'd police it is anyones guess.
 

Terry01

Jul 5, 2017
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I started with a real cheap kit,everything for £15 or something like that. A junk iron,lead free solder and a dod of supposed flux! I almost gave up before I started! I watched a couple YouTube videos and worked out why I couldn't get the solder to work. I got a better iron,decent solder and some decent flux. It worked wonders! Another thing that helped me was getting a couple Hakko tips (not copies) for my iron. My solder station is a Hakko copy so accepts the proper tips. When you compare them to the copies they are chunkier and better made. Worth noting.
 

kellys_eye

Jun 25, 2010
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I got a Hakko soldering station copy and the suppliers were supposed to send a selection of different bits for it but when it arrived they were all identical bits (wedges).

After an email complaint and a two week wait they sent me the proper selection only the tips they sent were GENUINE Hakko's - seems like rather than get negative feedback (or be made to repay the full cost) they sent out the real thing as compensation.

No complaints from me :D
 

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