Soldering temperature and wattage

[Bradd]

I see lots of folks saying things like "don't use a soldering iron over 25W for this project" or otherwise specifying heat according to wattage. I presume these people are talking about uncontrolled irons, yes?

I use a Weller WES51 station with controlled variable temperature. What temperature setting should I use with 63/37 solder? I used 600°F for my first couple of projects, but I have heard recommendations ranging from 600–750°F and I'm really not sure what is best for small electronics like guitar pedals.

Also, are there any situations where I actually need to be careful about wattage rather than temperature? If so, what does that mean for the WES51? It's rated 50W, but I'm not sure what that means in practice.

[dont-tase-me-bro]

Not sure if it's the proper way, but I solder at 750

[ggarms]

I use the same iron and rock 750-775.

[morganp]

I too use the same solder and iron, I keep it around 750ish and it works great.  I try to subscribe to the "get in and out quick" school; I think it's easier to cook components with lower heat and too much time, where 750 will get that 63/37 flowing quick.  You want to keep it to 3 seconds max per connection for stuff like PCBs.  If it's not working, let the components cool down for 15 seconds or so and try again, no need to roast 'em.

[alanp]

I use a 40W pencil iron -- it's 40W all the time, no faffing around with setting any kind of fancy temperature.

Well.

There are two temperature options -- either off, or on. That's it, really.

It's worked well for valve amps, a ton of pedals, wiring up the Cabronita, and all of my synthwork.

[selfdestroyer]

I have always used around 750 from my Weller WESD51. I was taught it was good to "get in and get out" and have always followed suit. Also, in my experience it helps the soldier run smoother and takes less time to soldier overall.

Update: I should add that its been a LONG time since I actually had a "cold" solider joint. Im not 100% sure if thats just dumb luck or the result of a hotter iron.

Cody

[mandrewbot3k]

I run at 773.6F. (I set it at 412C, I don't know why I just do.)


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[RobA]

I see lots of folks saying things like "don't use a soldering iron over 25W for this project" or otherwise specifying heat according to wattage. I presume these people are talking about uncontrolled irons, yes?

I use a Weller WES51 station with controlled variable temperature. What temperature setting should I use with 63/37 solder? I used 600°F for my first couple of projects, but I have heard recommendations ranging from 600–750°F and I'm really not sure what is best for small electronics like guitar pedals.

Also, are there any situations where I actually need to be careful about wattage rather than temperature? If so, what does that mean for the WES51? It's rated 50W, but I'm not sure what that means in practice.

The spec sheet for the solder you use should list the temperature requirements for the solder. For example, I use this SN100C solder http://www.aimsolder.com/sites/default/files/glowcore_cored_wire_rev_8_2.pdf. The temp requirements for it are 370°C to 425°C. I run my station at 410°C when using this solder.

Many parts will list temperatures for various soldering techniques in their spec sheets too. Although, I've never paid any attention to any of these. As long as you don't sit on the part forever, it's going to be pretty hard to damage most of them doing any sort of normal soldering technique.  The one big exception to that claim seems to be cheap switches.

The temperature is what's important for melting the solder. And using a eutectic solder type (like 63/37) means that the solder is going to do the phase change uniformly at the given temperature. For a temperature controlled soldering station, the wattage rating is really telling you how much heat reserve the station has. Assuming that the tips are good and the iron can deliver the heat, it's telling you how much heat you have to deliver to the mass of the part. If you don't have enough heat to deliver to more massive parts, then the temperature will sag and it will take longer to heat the part to the temperature that the solder needs to be at. That's bad because then you have to sit on the part longer and deliver more total energy into the part while still possibly never getting to the temp that the solder needs to be at to completely change phases and bond correctly when you remove the heat.

For a temperature controlled station, having a higher wattage isn't going to hurt. I guess you could purposefully make it hurt by sitting on the part indefinitely, but you aren't going to do that. When the solder melts, you are going to pull off and move on and the station is regulating the temperature so that the full amount of heat available isn't being pumped into the part. Really, having more reserve heat energy that can be delivered in a given amount of time at a fixed temperature is only going to make it safer to solder the parts.

For a non-temperature controlled iron, this isn't true. The iron delivers the amount of heat per second (Watts) that it's specified to and the temperature is a function of the heat delivered. In this case, you can damage the part (and the solder) by having them at too high a temperature. If you don't have enough power from a fixed power iron, then you will have to sit on the part longer (in the same way you would with a too low power station) and the total amount of heat you have to deliver to the part to get the joint up to temp (if ever) may be too high and cause the temperature of the part itself to become too high.

The short answer is that in a good temperature controlled station, too much power isn't a problem. In a non-temp controlled iron, the correct power rating (and good technique) is much more critical.   

[rullywowr]

I have the same iron, but digital (WESD51) and I rock it around 740-750F. Get in, get out quick.

[Bradd]

The spec sheet for the solder you use should list the temperature requirements for the solder. For example, I use this SN100C solder http://www.aimsolder.com/sites/default/files/glowcore_cored_wire_rev_8_2.pdf. The temp requirements for it are 370°C to 425°C. I run my station at 410°C when using this solder.

Thank you! This is very helpful information – for solder that has a data sheet. The Kester solder that I just ordered recommends 600–700°F for its leaded solders, for example. Unfortunately, I can't find a data sheet for the MG Chemicals solder I've been using, but it sounds like 700°F should be a reasonable setting.

[davent]

The spec sheet for the solder you use should list the temperature requirements for the solder. For example, I use this SN100C solder http://www.aimsolder.com/sites/default/files/glowcore_cored_wire_rev_8_2.pdf. The temp requirements for it are 370°C to 425°C. I run my station at 410°C when using this solder.

Thank you! This is very helpful information – for solder that has a data sheet. The Kester solder that I just ordered recommends 600–700°F for its leaded solders, for example. Unfortunately, I can't find a data sheet for the MG Chemicals solder I've been using, but it sounds like 700°F should be a reasonable setting.

Googling the MG Chemicals solder, catalogue #, for the stuff i have a hit on Digikey's website that gives a melting point of 361ºF (183ºC) which is pretty out of whack with what's been quoted in this thread. I use that ubiquitous Weller set at 700ºF for this solder and the Kester i have.

http://www.digikey.ca/product-detail/en/4880-18G/473-1111-ND/2177387?WT.srch=1&WT.medium=cpc&WT.mc_id=IQ66158182-VQ2-g-VQ6-46426603745-VQ15-1t1-VQ16-c

Datasheet confirms the MP.
http://ca-en.alliedelec.com/images/products/datasheets/bm/MG_CHEMICALS/70125674.pdf
dave

[Govmnt_Lacky]

I have the same iron, but digital (WESD51) and I rock it around 740-750F. Get in, get out quick.

Exact same iron over here. I run at 700 using Kester 0.031 Rosin Core.

Never had a cold joint. Get in/Get out as other say. 

[gtr2]

750 here too... .031 Kester 66/44

Josh