Soldering temperature question

[Mp3]

I don;t remember why I chose this temperature, or stuck with it for so long, but i remember back when i got my first soldering iron with temperature control, i read something to say to try soldering around 300c and see how that works.

I've been using my soldering iron at 300c or just barely any higher for probably 15 years.

I was googling yesterday shopping for new tips for my iron, and somehow stumbled upon not one but several discussions online where many people say they solder around 370-400C always.

Why solder so hot? I'm genuinely curious, i never really tried a temperature higher than about 300 since i found it to work, and it seems that the "slower" heating of ~300C makes it less risky when repairing vintage PCBs which may not be in great shape and require lots of care when performing maintenance.

I only ever solder small dense PCBs, often a mix of dense thru hole and larger SMT, so even though i may use a lot of wick doing repairs, i almost always have a very fine pencil tip on my iron. Maybe i'm wrong, but i felt if i iron at 400C, i may ruin stuff by accident.

[IanB]

I think there is no "right" temperature. It could depend on the kind of solder, the kind of flux, the size and capacity of the iron, the things being soldered, and so on. Lead free solder requires higher temperatures than lead solder.

You should adjust the temperature until the soldering process goes smoothly, so that joints are completed in 2-3 seconds, and without excessive smoke from the flux, and without damage to the components being soldered.

[tautech]

I was googling yesterday shopping for new tips for my iron, and somehow stumbled upon not one but several discussions online where many people say they solder around 370-400C always.

Maybe for that Pb free muck but you don't wanna go that high with leaded solder. 

325C is where my cheap station spends most of its time and if I need better thermal transfer it's time to go to a larger tip. 

[wraper]

For lead free my temperature is usually in around 370-380^oC range (ERSA I-CON) when I rapidly solder a huge amount of solder joints of mixed thermal mass. This way I can solder around 30-40 solder joints per minute. For lower thermal mass one offs I might use something like 340-350^oC.

[wraper]

i almost always have a very fine pencil tip on my iron.

I usually use 2 or 2.4mm mm (0,08" or 0.1") chisel tip even for 0603 SMT. It's best to use largest tip you can for the job. Does not matter if it's twice larger than pad. This way you can do job faster and better. I use small tips only in some special cases as they provide way worse heat transfer. If solder joint does not melt within 1 second, you are doing something wrong.

and it seems that the "slower" heating of ~300C makes it less risky

If you heat for several seconds at "low" temperature, and especially if you strongly push tip onto solder joint during that time, it's actually way worse for PCB rather than soldering much faster at higher temperature.

[KL27x]

1. production or prototype. If ad hocking something as you design/debug, then lower temp would be preferred to prevent oxidation while the iron is NOT soldering. Even if it takes longer to reflow the joint.

If doing production soldering you will keep the iron busy with less downtime, so higher temps will be more practical and efficient. You may also be doing many similar joints, so you can fine tune the temp for the best efficiency. In prototyping or repair work, you may choose a setting that is closer to good for "everything."

2. tip type. If you use a small pointy tip, you will need higher temp. If you test the temp of Metcal tips, you will find this is why the temp is listed as a range. The pointy tips have a higher setpoint than the fatty tips from the same temp rating category.

3. PCB type. Multilayer with internal ground planes? You will be bumping up the temp

That said, I keep my iron around 315C-325C for most things, using a 2.5mm bevel tip and working on 2 layer boards. And in short, the exact temp is a tradeoff between time to flow and rate of flux burning and oxidation/crusting of the tip (because this affects how often you need to clean and retin the tip, slowing things down).

heating of ~300C makes it less risky when repairing vintage PCBs which may not be in great shape and require lots of care when performing maintenance.

"Damage to components" is pretty low down in priority in the temp I choose. Most stuff, dwell time is all that matters to limit heat to the component. I have experienced heat damage (to tiny SMD resonators which the datasheet showed in hindsight are super sensitive), and that was due to oven reflow.

[Shock]

There is an ideal temp window in different soldering situations (tip geometry, solder type, target type and size) and you need to keep your tip within that window to ensure proper heating of the joint and wetting. What is totally inappropriate in one situation can be exactly what is needed for efficient soldering in another situation.

Beginners tend to sit on the joint for a long time and take multiple stabs, if you were soldering at a really high temp this is where damage can start to occur. After gaining experience you get a feel for how the solder is flowing into the joint, typically you should aim to spend 2 seconds.

Have you seen the old Pace videos on youtube? They explain just about everything you need to know. Even though they are a bit dated they are still applicable today.

[Mp3]

i almost always have a very fine pencil tip on my iron.

I usually use 2 or 2.4mm mm (0,08" or 0.1") chisel tip even for 0603 SMT. It's best to use largest tip you can for the job. Does not matter if it's twice larger than pad. This way you can do job faster and better. I use small tips only in some special cases as they provide way worse heat transfer. If solder joint does not melt within 1 second, you are doing something wrong.

and it seems that the "slower" heating of ~300C makes it less risky

If you heat for several seconds at "low" temperature, and especially if you strongly push tip onto solder joint during that time, it's actually way worse for PCB rather than soldering much faster at higher temperature.

Hmm, this is interesting. I use leaded solder (63/37) but i will try to use a temperature a little higher. It's not often, but there are times i have to strongly push the tip and wait a second or two for the solder to properly flow. I believe it that's not best practice.

I have not looked into the benefits of lead free solder at all, I have a giant roll of 63/37 that i have been working with for the last few years that still has plenty left. So i have not even considered using another type of solder.

 I had no idea it was okay to use a tip that large on SMT. Thanks for point that out.

[Mp3]

Have you seen the old Pace videos on youtube? They explain just about everything you need to know. Even though they are a bit dated they are still applicable today.

I have not and i will set aside time to find & watch them tonight. Thank you!

[tautech]

It's not often, but there are times i have to strongly push the tip and wait a second or two for the solder to properly flow.

Sounds like you're too cold or the tip isn't properly clean or tinned.
Get yourself a small beaker and stuff some soft brass or steel wool into it and plunge the iron tip into it a time or two to get it spotlessly clean.

I have not looked into the benefits of lead free solder at all,

Don't even bother unless you're into production or are forced to by legislation.
Electronics should be enjoyable not a way to accelerate baldness ! 

[wraper]

I have not looked into the benefits of lead free solder at all,

Don't even bother unless you're into production or are forced to by legislation.
Electronics should be enjoyable not a way to accelerate baldness ! 

But if you can get nice solder joints with lead-free, soldering with leaded solder feels uncannily too easy.

[Mp3]

I have not looked into the benefits of lead free solder at all,

Don't even bother unless you're into production or are forced to by legislation.
Electronics should be enjoyable not a way to accelerate baldness ! 

But if you can get nice solder joints with lead-free, soldering with leaded solder feels uncannily too easy.

Maybe i will buy a small roll of lead-free and try to improve my skills

[Jwillis]

I have not looked into the benefits of lead free solder at all,

Don't even bother unless you're into production or are forced to by legislation.
Electronics should be enjoyable not a way to accelerate baldness ! 

But if you can get nice solder joints with lead-free, soldering with leaded solder feels uncannily too easy.

Maybe i will buy a small roll of lead-free and try to improve my skills

 I might consider lead free flux as well. Since lead free solder melts at a higher temperature standard rosin flux would burn off to fast .This can cause poor welds  and cause a lot of blackening of your tips. Lead free flux activates at a higher temperature.

[DBecker]

My go-to is lead solder, a knife tip, and a temperature of 260C.  I only go higher if something isn't working, and then I'm very careful about heat damage.
I feel that I should be working at 240C and am cheating with 260C.  I'm a little surprised that people are comfortable with over 300C.

[KL27x]

I'm a little surprised that people are comfortable with over 300C.

Check the temperatures of Metcal/Thermaltronics tips.
http://www.thermaltronics.com/mseries_ref.php

The 700 series is recommended for general use with lead solder. The temp range is from 350C for the fatty tips up to 398C for the needle-pokers. The 800 series for leadfree ranges from 420C-475C.

Even the extra low temp 600 series bottoms out at 325-358C.

When you touch the iron to a heatsink like a PCB, the temp at the joint will drop well below the set temp of the iron. Despite the iron having more power, it can't compensate for this drop. The skinnier the tip and the more copper and mass in the board, the more drop you will get. You need to at least be able to reach and maintain 200C at the joint. But you also might want a higher temp just to get the joint to flow faster. You just lift it away once the joint flows.

That said, I have never set my 888 higher than 400C, and anything higher than 340-350C or so, I make a point to turn it back down as soon as I'm done. At ~350C or higher, I find the tips will darken and oxidize fairly quickly if forgotten for a spell. Much below that, my Hakko can be left on for 20 hours without any noticeable problem with tip life. Why not just leave it at 340C minimum, then? Well, depends on the joints. If the joint flows just as fast at lower temp, it might mean you don't need to clean the tip as often. (or breathe as much flux fumes)

[Nerull]

I use pretty much exclusively Metcal 700 series, and I've never had a problem with heat damage.

A similar thing can occur in welding, where people are terrified of heat damage so they use the lowest amperage they think they can get away with. This tends to actually increase heat damage as instead of getting the job done and getting heat off the part you sit there forever trying to get it to melt and greatly increasing heat soak. Heat transferred into the part is a function of tip heat *and* time. If you can work faster with a higher temp this can result in less heat transfer and less heat damage.

[tooki]

All of my soldering with a soldering station has been with my Ersa I-Con nano at home and JBC at work. I find that for lead-free, I usually stay around 330, for leaded around 300, for typical thin THT or SMD soldering with a 1.6-2.4mm chisel, not onto ground planes. Higher temps do work better for larger joints, but the higher temps cause the solder on the tip to oxidize so much faster that it can slow me down due to needing to “wash” the tip before use much more frequently.

If I ever get an ADS200 (or a “big” I-Con station), I may see how it is to set a very short setback timer, since these all reheat from setback in seconds, and then use a higher temp.

[tautech]

My go-to is lead solder, a knife tip, and a temperature of 260C.  I only go higher if something isn't working, and then I'm very careful about heat damage.
I feel that I should be working at 240C and am cheating with 260C.  I'm a little surprised that people are comfortable with over 300C.

Is your station temp accurate ? How would you know ?
I don't know if mine is or not and don't even care, 325C is just what the pot knob is set to and if I need more I change the tip or wind more heat on....or off.

Once you get the feel for soldering you can do it with a flame heated lump of copper or the old uncontrolled fire sticks many of us started with. For fine work they do need some heat control and an incandescent light dimmer was often used.

Dwell time on the joint is the secret to not lifting traces or damaging components and experience gained from harvesting parts from old PCB's is invaluable in learning the 'art'.

I only went to a cheap dual station for the hot air and to have a single unit on the bench and to have a range of tips for SMD work. Knife tips are real good for SMD passive rework.

[Vovk_Z]

My go-to is lead solder, a knife tip, and a temperature of 260C.  I only go higher if something isn't working, and then I'm very careful about heat damage.
I feel that I should be working at 240C and am cheating with 260C.  I'm a little surprised that people are comfortable with over 300C.

It depends on calibrating your soldering station with each exact tip too. I usually work with 270-280 C (T12 station, T12-D24 universal tip).
When 260 C - it starts to take some time to solder even small items so usually I don't use such (low) temp.
When 300 C - tip starts to oxidize fast, so I use that (high for me, 300-320C) temperature only for large wires.

[Mp3]

I tried a couple of those chinese T12 soldering stations, but they were too unreliable, i was having all kinds of issues with them going cold. My ts100 is much more reliable, but it's not ideal for all day use, and isn't ESD safe.
I am waiting on a new handle to get here before i can use my Hakko 936 again, but i've been awful tempted to get a ADS200.
I know that's off topic.

I watched some of the pace soldering videos, learned a few things, will try to run my station just a bit hotter and maybe try using bigger tips. But i have not really had issues for my purposes using pencil tips most of the time.

[DBecker]

My go-to is lead solder, a knife tip, and a temperature of 260C.  I only go higher if something isn't working, and then I'm very careful about heat damage.
I feel that I should be working at 240C and am cheating with 260C.  I'm a little surprised that people are comfortable with over 300C.

Is your station temp accurate ? How would you know ?

I use a 'Hakko 191' (from China, probably unlicensed).  It's consistent with thermocouple measurements.
I've designed my own soldering station controller (history-based overshoot control, not PID), so I'm familiar with the issues.  But most of my soldering is using a commercial station.

[ferdieCX]

I have an ERSA I-CON 2 and use almost only leaded solder
i-Tool at 290 ºC for soldering thin cables to connectors, 300 - 320 ºC for soldering trough hole and 0805 SMDs
For really massive components, I hook to the station the Power-Tool, mount the biggest usable tip and set it to 320 - 380ºC
In the seldom occasions when I have to use unleaded solder, I set the iron to about 350 ºC

[Jwillis]

I use a 120W TS1200A  with TSS02 tips. Most of my soldering is done at 185C (365F) with 63/37 solder and always get excellent results with little fouling of the tips. To hot and the flux burns of and gives really poor results. I'll only go to higher temperatures for wire gauges thicker than 8 But flow is really restricted.Its more like bead welding at that point . High wattage irons will  hold the temperature better than low wattage irons .
Other things to consider is whether the solder is eutectic or not. This means the different components of the solder melt at the same temperature and solidify  at the same temperature. For example 50/50 solder is Non-eutectic and has a range of temperatures.Not to say it isn't a good solder , it's just going to give different results.
I've used some lead free solder with fairly good results but I have to admit to having less experience with it. Probably because of the flux I used.
I go by this little chart I found and it seems to work. As far as I know these are all eutectic solders . I'm a little apprehensive on using CASTIN for the cadmium content but I'm probably just being paranoid .
The big thing is not to go to hot because oxidation accelerates at higher temperatures and can give poor results. Especially important not to exceed the temperature of your flux there by defeating it's purpose.  Your flux should melt just below the melting point of your solder.If your getting alot of excessive smoke your welding to hot.

[Shock]

I use a 120W TS1200A  with TSS02 tips. Most of my soldering is done at 185C (365F) with 63/37 solder and always get excellent results with little fouling of the tips.

The look on your face when you discover the station is displaying Celsius temp and you thought you were reading Fahrenheit will be priceless.

[Jwillis]

 

The look on your face when you discover the station is displaying Celsius temp and you thought you were reading Fahrenheit will be priceless.

SMC component soldering is done at 185C , Through hole is around 250C. I don't need any more than that . Heavier gauge wire I have to go higher for sure .Very rarely do I need to go higher than 350C and that for 14 gauge solid wire. I can tell the difference between Celsius and Fahrenheit since I have to use both all the time.