Soldering iron temperature?

[bill0287]

I recently got my first temperature controlled soldering iron. What is the ideal temperature setting to use when working on stomp boxes?

[Govmnt_Lacky]

600-650 Fahrenheit for lead-based solder
650-700 Fahrenheit for lead-free solder

[R.G.]

I use 650F for small stuff like individual parts and PCBs. This happens to suit my technique of "get in fast with high heat, make the joint, then get out fast".
There really isn't an ideal temperature for a soldering iron, only a range of temperatures that work well with your technique and what you're soldering.

What you're looking for is a way to (1) get the parts being soldered to a temperature hotter than melts the solder, (2) melt the solder with the parts being soldered, not the iron itself, (3) get the solder to flow as a liquid to all parts of the joint you want solder in, and (4) get the iron off the joint quickly so that continued heat does not damage the parts being heated or the PCB. Long heating with temperatures just above the melting point of the solder itself is a recipe for heat damaging parts and lifting PCB foils.

Use 60-40 or 63-37 tin-lead solder unless you just can't (country laws, for example) or won't (personal compunction). Lead free solders require more heat, higher temps, and are more temperamental.

[Clint Eastwood]

I use a really cheap little iron, and adjust the temperature according to the job, as low as possible. A large mass of metal requires more heat. In most cases, with leadfree solder, only around 480 Fahrenheit. (That is, with the dial set at that temperature. Don't know how accurate it is..)

[Ice-9]

I use a really cheap little iron, and adjust the temperature according to the job, as low as possible. A large mass of metal requires more heat. In most cases, with leadfree solder, only around 480 Fahrenheit. (That is, with the dial set at that temperature. Don't know how accurate it is..)

For me, if i used lead free solder 480F just would not cut it at all., but I do use very small 1mm tips. I prefer about 650F/345C and that is for leaded solder, That temp for me for unleaded just would not work.. I had to convert to Celsius as I am from the UK.

A little tip for de-soldering unleaded joints, re-solder the pads with leaded then de-solder. (as long as your happy to use leaded solder).

[R.G.]

I'm with you Mick. 480F (if the iron is showing him the right stuff, as he notes) is too low for me. I went through a period of running about 525F and inched my way up as I found that I had more overheated and cold-solder joints to repair.

@ bill: I alluded to timing being important in soldering. Heat transfer is time dependent. To make a soldered joint, every part of the metal to be soldered and all the solder in the joint have to get to over the solder's melting temperature so the solder can "wet" the metal in the joint. In thinking about soldering, you can think of metal masses as "capacitors" for heat and temperature difference as the voltage/pressure that makes heat flow. The metal mass "capacitors" charge up with heat (analogous to electrical charge) through the thermal resistance of the contact points with the surface of the iron.

Just like with electrical charge, a higher temperature difference forces heat to flow from the iron to the joint faster. So if your iron is hotter, you can get whatever is in the joint hotter faster. You have a built-in temperature alarm: the solder flows liquid when the joint is at a high enough temperature, which is why beginners are always advised to touch the solder to the parts being soldered, not the iron itself. So far, so good.

Soldering damage happens when the already-hot joint flows heat out of the joint into the stuff being connected by soldering the leads. This secondary heating also involves thermal resistance and the time to fill up thermal capacitance. If you use a soldering iron down at just above the flow temperature of your solder (~380F to 400F) then the heat has time to flow through the joint and back up the leads to the parts on the leads, and these will be hotter for quite a while before the joint gets to all-solderable temperatures.

If you use a hotter iron, the heat flows into the actual joint parts really fast, so the joint gets up to solder-melting temperatures before the heat has time to flow up to the rest of the parts on the lead being soldered.

Here's an illustration. I sometimes use cut-off resistor leads for short connecting leads, and will tin them with a soldering iron. I hold the ~ 1" cutoff lead by one end and touch it with a tinned soldering iron lead. With a 650F iron, I can easily tin the free end and remove the iron from the lead before my fingers get burned an inch away. A colder iron makes this very difficult to do without getting burned. It's an easy way to see how hotter soldering irons make it easier to make a soldered joint flow the solder before the heat conducts off to burn something you don't want burned.

[ElectricDruid]

+1 agree with RG

Over time, as I've got more skilled, I've tended to use hotter iron temperatures. This is a result of being able to to do the same job quicker and more efficiently. When *I* was slower, I needed a lower iron temperature to avoid toasting things. Now I'm better at it, I can dab some heat on something, get some solder in, watch it it flow, and get the heat off, all in much less than a couple of seconds. Thirty year's practice counts for something!

Currently I use my iron set at 350C, which is 662F. That's "hot, but not too hot" and reflects where I'm at. I used to run it cooler, but as I got better at what I was doing, I went quicker and hotter. At that temperature, you don't want to hold it on the joints for long, but I mostly don't need to. Keeping the bit clean so you get a good heat transfer is crucial, but working with a mucky bit on your iron is a recipe for disaster whatever stage you're at.

HTH

[PRR]

{Not even thinking of my 450W Vulcan roof-patcher....}

My favorite iron for large audio projects (jack fields, ground buses) glows in the dark.

That seems to be 426-600C 800-1100F  https://en.wikipedia.org/wiki/Red_heat

Yes, that is very hot, and takes Tom's 30-year training to get in and out clean and quick. (I guess I'm over 50 years now.)

I do not understand 525F. That's not even a good beefsteak oven.

One month I had horrible trouble soldering with my second-best iron. Finally determined it was the building blowers. My workbench was right under an air vent. For a decade nobody changed filters or belts. Somebody noticed, and serviced the blowers. It went from near-zero to hardly-any, but that was enough to take the edge off my iron.

BTW: most modern Silicon can live and work at wet-solder heat for many-many minutes. But cheap PC board will shed copper in seconds. If you can find Polystyrene caps, be very very careful. A heat-melted shorted PS cap as the Miller compensation in a power amp will blow your whole day.

[Rob Strand]

The thing is,  as soon as you put the tip on a thermal mass the set temperature doesn't reflect the tip temperature.  Small tips will be at an effectively low temperature so you need to set the temperature higher.   If you match the tip with the work then the temperature difference is less. - not many people do that unless they have some big lump to solder.


See 10:18 and after.
Notable section after 12:11.  "tip temperature not that critical at all" because there's many factors.
https://www.youtube.com/watch?v=vIT4ra6Mo0s

Components, see bad joint examples at end,
https://www.youtube.com/watch?v=AY5M-lGxvzo

[Matthew Sanford]

See 10:18 and after.
Notable section after 12:11.  "tip temperature not that critical at all" because there's many factors.
https://www.youtube.com/watch?v=vIT4ra6Mo0s

That video was much better than a lot that I've read, thorough and to the point, and now I'm considering the next bigger tip.

[Clint Eastwood]

Great video. I will check from now on if I obey the no more than 2 second rule.
Since I find lead free soldering much easier than I feared, I suspect my iron is actually hotter than it makes me believe.

[Phend]

Been doing some soldering today, with new equipment.
I am a novice at this but like any sport each will have his/hers own techniques.
Finding that wire size, solder mfg, iron tip etc all play a part. Nothing new here.
I am using a small point tip, and small diameter solder.
Holding the tip perpendicular to the board, along the lead, works best for me.
Adjust the temp up until the solder melts fast, 700F for my rig.

[CheapPedalCollector]

I've been soldering for decades, I use 680F for leaded and 710-720 for lead free. I'd rather have hot joints with quick melts than heat parts too long.

[bluebunny]

Yeah, baby.  Hot and fast.   

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Oops.  Sorry, wrong forum...   

[Ice-9]

Here's an illustration. I sometimes use cut-off resistor leads for short connecting leads, and will tin them with a soldering iron. I hold the ~ 1" cutoff lead by one end and touch it with a tinned soldering iron lead. With a 650F iron, I can easily tin the free end and remove the iron from the lead before my fingers get burned an inch away. A colder iron makes this very difficult to do without getting burned. It's an easy way to see how hotter soldering irons make it easier to make a soldered joint flow the solder before the heat conducts off to burn something you don't want burned.

Yes, exactly this.

[EBK]

My Hakko defaults to 750.  I've never changed it.