What’s the proper soldering iron temperature for standard .031" 60/40 solder?

Question

I recently purchased a Weller WES51 soldering iron as my first temperature controlled iron and I'm looking for recommendations on the best default temperature to use when soldering.

I'm using mainly .031 inch 60/40 solder on through-hole components.

Answer 1

What’s the proper soldering iron temperature for standard .031" 60/40 solder?

There is no proper soldering iron temperature just for a given type of solder - the iron temperature should be set for both the component and the solder.

When soldering surface mount components, a small tip and 600F (315C) should be sufficient to quickly solder the joint well without overheating the component.

When soldering through hole components, 700F (370C) is useful to pump more heat into the wire and plated hole to solder it quickly.

A negative capacitor lead to a heatsinking solid pour ground plane is going to need a big fat tip at a much higher temperature.

However, I don't micromanage my soldering temperature, and simply keep mine at 700F (370C). I'll change the tips according to what I'm soldering, and the tip size really ends up determining how much heat gets into the joint in a given period of contact.

I think you'll find that very few soldering jobs will really require you to change your tip temperature.

Keep in mind that the ideal situation is that the soldering iron heats up the joint enough that the joint melts the solder - not the iron. So the iron is expected to be hotter than the melting point of the solder so that the entire joint comes up to the melting point of the solder quickly.

The more quickly you bring the joint temperature up and solder it, the less time the soldering iron is on the joint, and thus the less heat gets transferred to the component. It's not a big deal for many passive or small components, but it turns out that overall a higher tip temperature results in faster soldering and less likely damage to the component being soldered.

So if you do use higher tip temperatures, don't leave them on components any longer than necessary. Apply the iron, apply the solder, and remove both - it should take just a second or maybe two for surface mount, and 1-3 seconds for a through hole part.

Please note that I'm talking about prototyping, hobbyist, and one-off projects. If you are planning on doing final assembly with the iron, repair work for critical projects, etc, then you'll need to consider what you're doing more carefully than this general rule of thumb.

Answer 2

I normally set my WSD81 to 350°C, for leadless solder or big stuff I've used 360°C and for small SMD stuff 340°C.

The solder doesn't just need to melt, it also needs to wet the surfaces, which happens faster at higher temperatures.

Answer 3

I use a Metcal system and the cartridges for standard lead solder deliver 600F. It's important to use the correct size tip for the job in hand, Metcal recommends one that is about the same size as the object being soldered, to avoid damage.

Metcal has this useful document on soldering techniques

Answer 4

My strategy is to always have the iron as hot as possible, then try to minimise the time I have in contact with components.

A hot iron will melt solder immediately on contact. Whereas, a cooler iron will need to be held in contact for a while first, which might do damage to the PCB or parts.

Though, apparently, between 600 and 700°F is ideal.

Any higher and you might:

• Damage components
• Reduce the lifespan of the tip
• Melt insulating wire
• Burn off flux
• Vapourise lead

http://blog.tubedepot.com/?p=226

Despite the risks - I'd still recommend short bursts at high temperature for surface mount and through hole construction. Works for me.

Answer 5

I found these two links, with the following information:

Basic Soldering Guide:

The melting point of most solder is in the region of 188°C (370°F) and the iron tip temperature is typically 330°C to 350°C (626°F to 662°F).

Soldering Basics:

Although tip temperature is not the key element in soldering you should always start at the lowest temperature possible. A good rule of thumb is to set the soldering iron tip temperature at 260°C (500°F) and increase the temperature as needed to obtain the desired result.

With these as a guide and a bit of experimentation I've found that 550°F generally heats the lead and pad up to the appropriate temperature within a couple seconds.