Soldering Temperature leaded solder - problems with melting point - Page 1
Forum section: electronics / beginners

author: collinember
author_rank: Newbie
timestamp: May 14, 2023, 09:28:47 pm
content: Hi,I am new to the world of electronics and today did the first steps in soldering with a DS0138 mini kit. I use leaded solder from Stannol (HS 10 - about 40yrs old), and have a new Weller 1010 soldering iron. I also have an old Stannol soldering iron, but its temperature range only starts at 340 deg. Celsius.The question I have is this: the HS-10's melting point should be around 191 deg. Celsius, so I set the Weller to 200 degrees. But I wasn't able to solder any parts until I increased the Weller's temperature to about 300 degrees? Attaching the iron to a component for about 5-7 sec - even than the solder won't melt. The point of buying the Weller - being able to solder at lower temperatures - is gone for the moment, but I am sure I'm doing something wrong here. Can anybody help me out what I maybe doing wrong?Thank you!

author: Benta
author_rank: Super Contributor
timestamp: May 14, 2023, 09:54:04 pm
content: Your Stannol HS-10 is normal 60/40 eutectic, so that's fine.But your low-temperature thinking is wrong.Standard tip temperature is around 350 C for PCB soldering. The Weller WTCP station is even 370 C as standard.

author: ataradov
author_rank: Super Contributor
timestamp: May 14, 2023, 09:55:34 pm
content: Just getting to the melting temperature is not enough. The solder must flow, not just barely melt. 320 C is a "regular" soldering temperature for 60/40 solder.Plus you don't mention flux at all, and that is also a critical component of the process.I generally don't like to go higher than 320 C because it start to burn the flux much faster than I like.

author: RoGeorge
author_rank: Super Contributor
timestamp: May 14, 2023, 09:57:07 pm
content: 200*C is rather low even for Pb solder. 5-7 seconds is too long. Use the thickest and shortest tip that can still fit the job, for example a chisel at least as wide as the pad. For SMD ICs always use flux.You may also want to see these for extra hints:Basic Soldering Lessons 1 - 9 (from PACE)https://www.youtube.com/playlist?list=PL926EC0F1F93C1837

author: Benta
author_rank: Super Contributor
timestamp: May 14, 2023, 10:15:38 pm
content: Quote from: ataradov on May 14, 2023, 09:55:34 pmWell said.It's an experience thing, but the sweet spot is somewhere in the 320...370 C range. It also depends a lot on the thermal mass you're soldering vs. the tip size. As soon as you connect the tip to the soldering point, its temperature will drop.Stannol HS-10 has integrated flux. Good solder.

author: ataradov
author_rank: Super Contributor
timestamp: May 14, 2023, 10:35:12 pm
content: Integrated flux only helps if you can bring the fresh solder to the solder point, which in practice would only mean though hole components. I don't see drag soldering working without added flux.Plus if it is really 40 years old, it can probably use fresh flux.

author: jonpaul
author_rank: Super Contributor
timestamp: May 15, 2023, 07:31:40 am
content: neither soldering iron spec, temp setting conmtrol nor tip temp measurements are accurate or repetable.Erros of +/- 20 C are usual.Dependoing on the config, conductor size, flux, solder the temps are substantilaay hoigher the the MP.A non eutectic solder has a wide range of plastic phase, besides the solid and liquid phase.See app nots from Kester, Multicore, AIM, etc.We use only Kester 44 core 63/37 leaded on wore solder for porptos anmd repair and SN100C bar for SMD , solder pots if RoHS is requiredj

author: EPAIII
author_rank: Super Contributor
timestamp: May 15, 2023, 07:47:46 am
content: The other thing, after temperature, about soldering is the amount of heat that is available. If you are trying to solder parts with a relatively large mass of metal that also conducts heat rapidly (think copper) then the heat energy in the tip of the soldering iron will rapidly dissipate into that part and the temperature of the tip will drop. It may come back after some time OR, if the part keeps conducting that heat away from the area where you wish to melt the solder, then it may never get hot enough to melt the solder.This is why temperature controlled irons are so pervasive. You do not want to bring most electronic parts or the PC boards to an excessively hot temperature as that can damage many parts or the PC board itself by de-laminating the copper foil. So, it is important to keep the temperature DOWN to a reasonable level. BUT, when there is a large mass of metal in the part or in a ground or power plane on the PCB, the tip temperature can drop and take some time to recover. So the soldering process can take some time or even fail altogether.Temperature controlled irons have relatively large heating elements that can produce heat rapidly, BUT by controlling the temperature they prevent damage due to over heating or over temperatures. The trick is to bring the temperature of the parts UP to the needed level quickly but no higher. Then you apply the solder which will flow into the joint. The flux should already be there or at worst come with the application of the solder. Ideally, the whole process only takes seconds.If you use a non temperature controlled iron that is too small, it takes a long time to heat the joint and you may get a poor joint. If you use a non temperature controlled iron that is too large, then you can easily apply too much heat and damage either the parts or the PCB or both.If you are not using a temperature controlled iron, I strongly suggest that you obtain one. Some of them are expensive, but others are more seasonably priced. I have an import (Chinese) model with a digital temperature control and display that cost only $40 USD. It works just as well as my older Weller WTCP which cost twice as much around 50 years ago and current versions are at least twice again that much today. I doubt the Chinese one will last that long.

author: tooki
author_rank: Super Contributor
timestamp: May 15, 2023, 08:04:48 am
content: Quote from: collinember on May 14, 2023, 09:28:47 pmWatch this old video series:https://youtube.com/playlist?list=PL926EC0F1F93C1837The whole thing takes under an hour, and I promise you, it's time well invested. I have never found a better explanation of the soldering process.

author: collinember
author_rank: Newbie
timestamp: May 15, 2023, 06:26:11 pm
content: wow, thank you all for your input!Looks like I missed the fact that the tip temperature can be quite a bit lower than what I have set the soldering iron to. Today I've set it to 320 deg (C) and things went smoothly.I solder electronic synthesizer parts (actually I'm a musician trying to put some so called "eurorack" synthesizer DIY kits together).The Weller 1010 does have a temperature control, but I am not sure how reliable it is. Actually I thought of returning it and get another one.The solder I use has a flux core - if I hear you right this is not a good idea? (that Stannol HS-10 I thought - despite being old - has a good reputation. Although not sure of course if thats the right choice for electronics.)For now I only solder through hole parts, which may soon change though.Thanks again everybody - that was of great help! Much appreciated!

author: collinember
author_rank: Newbie
timestamp: May 15, 2023, 07:37:47 pm
content: Quote from: RoGeorge on May 14, 2023, 09:57:07 pmQuote from: tooki on May 15, 2023, 08:04:48 amVery interresting indeed! Amazing to see how technology has changed over the years but these explaination still hold true.Thank you - have learnt quite a bit !

author: ataradov
author_rank: Super Contributor
timestamp: May 15, 2023, 09:01:06 pm
content: Quote from: collinember on May 15, 2023, 06:26:11 pmYou can buy temperature calibrators, but for hobby use I would not bother. Just set the temperature that is not too high yet feels ok, and don't pay attention to what the number says.Quote from: collinember on May 15, 2023, 06:26:11 pmNo, it is fine to use flux core solder, but in many cases this is not enough. In case of though hole components you bring both solder and the iron to the solder point, so flux does not have time to burn out.With SMD, you are generally keeping solder on the tip of the soldering iron so by the time you get to the soldering point, there is no flux left. And you need to have the flux on the board itself.Plus if you are fixing up already soldered joint, you need to use separate flux.

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: May 17, 2023, 11:47:38 am
content: My Antex XS25 (25W) iron measures 390C and my Antex M12 (12W) measures 334C. These are basic non temperature control irons.The 25W iron has a bit around 3 times the mass of the bit in a Weller WE1010, it will easily “out perform” the Weller in terms of soldering large through hole pads, large plugs on 1/2” coax, etc.The little 12W Antex is similar in soldering ability to the Weller, the temperature is fine for both 60/40 and lead free solder. The 390C of the 25W Antex is too high and burns off flux too quickly and can result in tiny solder balls being ejected due to the high temperature.I also have a WE1010, which is OK, but not for large parts. The temperature indicated is pretty close to what my thermocouple meter shows, beware of the offset/cal on the Weller, mine is fine with zero offset.SJ

author: Psi
author_rank: Super Contributor
timestamp: May 17, 2023, 12:14:47 pm
content: It's all about pumping heat into the object to get it up to temperature.The piece of metal to be soldered is not levitating in a vacuum, everything is trying to pull heat away and spread it out to obtain equilibrium.To get the thing being soldered up to a temperature where solder will melt you need to pump in a lot of additional heat to compensate for all the heat being lost. The way you do that is having the iron tip hotter than needed to melt solder.So your iron is in the range of 320-400C in order to get your workpiece up to:- The temp solder will fully melt at- The temp flux will fully activate at