Soldering iron wattage?

notCardio

I walk the line
By chance I happened to read the previous questions about soldering irons, and it got me to thinking. (I know, I actually do that on occasion)

A newbie question that's probably been asked about a thousand times but, what are the appropriate wattages for our common applications?

What wattage for the PCB on a pedal, what for cables, and what for controls on a guitar? Or will all of those take the same wattage?
 

Chili

Site Moderator
Those little 30 watt pencil irons are just fine for what you mentioned. If your cables are larger than 14 gauge, you might consider more watts.

I find the best tool for a good soldering job is bifocal reading glasses with a high magnification lens so I can see what I'm doing.
:D
 

jamesperrett

Active member
I'd always recommend a 50-60W temperature controlled iron. The temperature control means that it won't be too hot for fine work but the higher power means that it will cope better with larger joints too. I spent my formative years struggling with the cheaper 25W irons that were often recommended so, when I started a Saturday job in a TV shop and tried the irons that the service engineers used I realised what I'd been missing.
 

skywaveTDR

Active member
I have used Weller products for many years and I do not often lift foils from boards. One must understand the thermodynamics of the iron as in when to us the broader section of the tip in comparison to the fine tip end. Using good solder like Kester 44 always helps. With a Weller I have changed those postage stamp sized chips with 84 pins up to the larger TO-3 transistors. The system is rated at 40 watts but is all depends on how you apply the 40 watts. In some cases like doing yard lights with 14 gauge wire the 40 watt iron will not do when it is winter out. That is when I get the Radio Shack 500Watt gun out and that will deal with the cold and larger wire. I still use Kester 44 as this stuff flows like solder should. Some Korean solder I have come across flowed as if it was slag. Slag is the garbage you remove from a vat when making bullets.
 

rob aylestone

Well-known member
25 Watt for me for audio stuff and circuit boards. 25W is too low to solder cable larger than 1.5mm2 - 35W will do it. I have never needed an iron higher wattage than that. I still have a huge drum of lead free solder that is maybe ten years old. The new lead free stuff I just cannot get on with.
 

dogooder

Well-known member
What temperatures do the different wattages bring the tips to? I have a variable station and no indication of wattage, only temperature.
 

easlern

Boredom artist
A 40 watt works fine for me when working with older lead solder. The silver stuff though (newer, less hazardous type), I can’t even melt that. So I’d recommend more than 40.

Cables and guitars seem to still use through-hole components in my experience, so they’re easy to work on. Pedals are using surface mount since the 90s though I think, so I don’t bother with those. They require better eyes and steadier hands than mine.
 

Gtoboy

Well-known member
530 ish is melt point for 64/40, my brother is electro repair and he says on small joins/pcb board 620 to 700 depending on the size minimum. He says he usually leaves it set around 800 deg but will go up to 900 for large repairs. (all temps fahrenheit). To low a temp will force longer contact which can damage the board so start around 800 and lower if needed, but beware if it takes longer to melt, raise the temp
 

ecc83

Well-known member
Bit late on parade I know but, I used a 48W Weller station for over 40 years and soldered everything from steel chassis lugs to tiny transistors. Much later I used the same iron to change an SMT reverb chip in an amp. (yes! It worked!)

Thing is, peeps often confuse 'wattage' with temperature. My beefy Weller only gets to about the same temperature as the rubbish old 25W Henley Solon or the almost as bad Antex.

A components 'solderability' is defined as X deg' C for Y seconds. So long as you stay within those limits you won't damage anything. in fact a 50W iron allows you to make a briefer contact.

Dave.
 

skywaveTDR

Active member
There is yet another item to add to the equation. Tip size and shape. In working with small joints the tip will have a reduced temperature as it takes longer to heat recover than the more broad part of the tip, So not only does it help to have an adjustable iron temp but it also matters how you use it with what tip. I am using the conical sharp tip on a Weller WES51 which is now an old model but over the years these solder stations have soldered thousand of joints without lifting any patterns and all my joints look shiny in comparison to what I encounter on these wave soldered boards. The Solder I use is Kester 44 as obtained from Kimco. I know a pound of Solder can be seen at some suppliers for around $45 but when bought in bulk (25 rolls to a case) you can get it for about $20. I bought the case and have sold some rolls to my trainees who will not use as much as me. Most Japanese decks are so poorly soldered that sometimes I use a roll a month.
 

Slouching Raymond

Active member
Mine is 15W, and is fine for most jobs. In recent years the components have got so tiddly and delicate, it is almost impossible to solder them without risking destruction.
 

ecc83

Well-known member
Mine is 15W, and is fine for most jobs. In recent years the components have got so tiddly and delicate, it is almost impossible to solder them without risking destruction.
I am sorry but this is a common misconception. A high wattage iron and I would class 50W as modest, does not lose heat to 'the job' and thus WITH PRACTICE you need to spend far less time in contact with the component. I have successfully changed a SMT reverb chip in a guitar amplifier. Some years ago. I have lost those skills and one eye so could not do it now. However with INTENSE concentration I can still build stuff.

People often say "I can't solder" Well people can't play guitar until they try and try and try! (another skill gone through lack of practice)

Dave.
 

ecc83

Well-known member
The factory where I worked with the irons employed at least 40 people to solder RJ45* jacks to PCBs and a good 35 of those people were ladies, some very young, not long out of school. If they could not learn to solder to a good standard they did not have a job for long.
I don't recall anyone getting their cards in ten years (well, not for bad soldering anyway)

Most of the gals that had been at it for a year or so could whip down a row of jacks in no ti,me flat and their work way almost always 100% fine. I had been soldering since I was about 12 but could not match their speed.

*Google "RJ45 jack" and you will see what they were doing. We also soldered a lot of "Krone blocks".

Dave.
 

skywaveTDR

Active member
Regulated solder stations still are subject to the laws of thermodynamics. This is why a tip of an Iron is less temperature than the more broad part as the heat transfer is at a different rate. In 47 years I have soldered a lot of joints- no I do not like or will not use lead free solder- that is simply foolish. I would agree that an experiened hand solder joint is way better than a wave solder board. The only problem with hand soldered boards is they bent over and left the leads long which takes a lot more work to change those capacitor after they have been in the deck for 40 years. I put them in so the leads are sticking up and then trimmed. I did a NE5532 in a walkman the other say SMD but the caps in the unit have all kinds of DC voltage jumping on one channel and the problem is the many caps I have here are not 5mm long so I will have to order small caps.
 

ecc83

Well-known member
Regulated solder stations still are subject to the laws of thermodynamics. This is why a tip of an Iron is less temperature than the more broad part as the heat transfer is at a different rate. In 47 years I have soldered a lot of joints- no I do not like or will not use lead free solder- that is simply foolish. I would agree that an experiened hand solder joint is way better than a wave solder board. The only problem with hand soldered boards is they bent over and left the leads long which takes a lot more work to change those capacitor after they have been in the deck for 40 years. I put them in so the leads are sticking up and then trimmed. I did a NE5532 in a walkman the other say SMD but the caps in the unit have all kinds of DC voltage jumping on one channel and the problem is the many caps I have here are not 5mm long so I will have to order small caps.
I may have read you wrongly Skywave but if you said you do NOT use Lead free solder then you would have a problem over here! If you are in a business and repair equipment you must use Lead free. (I think there is a get out for REALLY antique kit but I am not sure about that)

I am no fan of Pbfree but you do get used to it. You must however get the right stuff. I was given some real ***t to fix guitar amps with and struggled. Then I got hold of the solder they used on the actual production line (one range of amps is hand soldered) and all was fine.
I also believe the Lead in solder did little or no harm and it got banned here because of the association with TELead in petrol and there is little doubt that that WAS nasty. Same goes for Cadmium. Yes, it IS toxic but you would have to be pretty damn stupid to ingest enough plated bolts or CdS cells to get poorly!

Pbfree does have its advantages tho? Makes tacking experimental lashups a doddle because of its very fast 'freeze' time and it is mechanically much stronger than PbSn.

I am in fact almost out of solder and waiting on Amazon for more 60/40. Not that I do much these days.

Dave.
 

skywaveTDR

Active member
No I will not use Lead free until the lead stuff is not made anymore. I put a radio station together almost by myself and they provided lead free solder and it was nasty to work with. The 1/8" connectors that we buy melt with the temperatures that stuff requires so it is more difficult to use or you have to buy the most expensive Switchcraft or Neumann connectors. I get my solder from a company called Kimco that sold me a case of 25 rolls for $478. I am not buying the stuff for $45/ pound roll. I even have some older stuff here that was about $7.00 a pound from the 80's. Hey I have been using this same stuff for 47 years and it has not gotten me yet- No I do not chew on it either. Some people will put anything in their mouth such as hair and other strange items- I suppose Covid might have stopped them doing that now.

Kester 24-6337-0027 | Sn63/Pb37 Solder WIre, 44 Rosin, .031 diameter, 66 Core, 1 lb. | Case of 25 rolls

 
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