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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.

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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.

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    \$\begingroup\$ It sounds like I was erring a bit on the side of conservatism. I'll try 700°F or so and see if that gives me improved results. \$\endgroup\$ – Lawrence Johnston Mar 23 '10 at 3:25
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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 (~290°C) generally heats the lead and pad up to the appropriate temperature within a couple seconds.

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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°F and 700°F (~320°C - 370°C) 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.

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    \$\begingroup\$ So you would suggest 600 or 700°F? Or going straight up to 850°F (which seems like it might be excessive and risk damaging the parts from even short exposure). \$\endgroup\$ – Lawrence Johnston Mar 23 '10 at 0:35
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    \$\begingroup\$ My iron is as on max at 800°F (I use lead free solder). It's important to have a light touch when working with surface mount parts. For through hole, attach a crocodile clip or heatsink to the legs of sensitive components. \$\endgroup\$ – Toby Jaffey Mar 23 '10 at 0:45
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    \$\begingroup\$ The boiling point of lead is 1749C/3182F... You will not be vaporizing lead with your soldering iron. \$\endgroup\$ – NickSuperb Mar 2 '15 at 20:50
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    \$\begingroup\$ @NickSuperb vaporization is not an all-or-nothing process and you don't need to reach boiling point to release vapor. If this was not the case, your clothes on the washing line would never dry. See en.wikipedia.org/wiki/Vapor_pressure \$\endgroup\$ – Hugh Allen Aug 9 '16 at 2:28
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    \$\begingroup\$ @NickSuperb I'm not sure what you mean by "temperature required to vaporize Lead". A vapour pressure is a partial pressure, so assuming a vapour pressure of 2mbar at 1000C, the air would equilibriate to about 0.2% lead. \$\endgroup\$ – Hugh Allen Apr 21 '17 at 11:01
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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.

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THE PROPER SOLDERING TEMPERATURE IS HIGHER THAN MANY THINK! Many electrnoics hobbiest and technicians are misled when they hear things like temperature can add more damage than you started with. They are bombarded with thoughts surrounding solder melting points and somewhat led to think the key to professional work results is only low temperatures will do the job. That simply is not true!

Here are the considerations and my advice...

  1. Choose the right size tip for the job. Tip size requirements change with the area and job you are soldering. Larger tips transfer more heat quickly. Keep your solder tip close to the same size as the area you are soldering. Usually selecting a tip that will get the job done for 95% of your work is the best trade-off. It may be slightly smaller on some components and larger on others.

  2. Different components require different heat to achieve the similar results. You will learn this over time while soldering. Large capacitors, an example, will require more heat than other similar size parts.

  3. When using spooled solder alloy type matters. If you work with a specific type of solder select a temperature suited for that type. Otherwise, select a temperature that works well with all types.

  4. Are you soldering correctly? Pay attention to what your soldering iron is touching and how long it is there. Remember the rule, always allow solder wet the areas and get in and out quickly. Unless necessary never heat only the lead or pad. Heat both areas simultaneously.

  5. Faster in and away offers less chance to ruin a component. Heat dissipates at a given rate into the component body, this is slower than dissipation in leads and pads. Longer times with lower heat can often cause more damage than shorter times with higher heat because of this.

  6. Never let your iron touch the component body. Only touch the area to be soldered. Beware of direct heat transfer to component packages. Keep your solder tip on the area you are soldering.

  7. Always use solder flux and select the right type. Flux is essential. It cleans the area to be soldered, helps the solder wet surfaces to be soldered, reduces the amount of time to make the connection, greatly improves solder joints, and reduces the risk of component damage.

  8. Solder has to wet the surfaces being soldered. Never remove the iron to fast. After the solder melts it must wet the surfaces of all areas to clean and create a great connection.

  9. Preheating PBCs reduces chances of damage. Working on sensitive components and multilayered PCB's is better served by preheating the PCB. Preheating reduces the time required to solder, reduces damage to components, and helps prevent warpage or separation of PCB layers (board shock).

  10. Practice, practice, practice. Learn on a scrap PCB until the technique is perfected. During practice, I also like to see how long it takes me to displace a solder pad, destroy a component, or damage the PCB board. it is not necessary but I find it useful to know and it will vary with board quality and type.

  11. NEVER try to solder more than a single component lead at a time with an iron. Trying to save time by soldering several leads of a large IC is asking for damage. The damage that occurs due to prolonged heat transfer into the component body. Solder single leads to one pad at a time when using a soldering iron. (When desoldering it is normal to deviate from this since critical placement consideration and time is removed from the task.)

  12. HIGHER temperatures are usually safer than lower temperatures when soldering. In direct contradiction to what many believe this happens to be the real truth. Higher heat melts the solder and transfers heat to all of the solder areas faster creating a good connection. It also allows for the solder to wet the areas completely. (Heat transfer into component body occurs at a different and generally slower rate making higher heat combined with fast in and fast out a great rule to follow.)

  13. Shield sensitive areas from damage. Plastics and some components need shielding when soldering large components nearby. Use of Kapton tape and small heatsinks (an alligator clip) on the area will both help reduce heat transfer. (looking up component specs is always less costly and time-consuming than ordering replacement parts after damaging them.)

  14. Similar but different rules apply to Hot Air or Infra Red soldering than to a soldering iron. It may help to make a list for each until you learn the differences.

  15. Keep the area being worked on clean. Use 99.99 percent alcohol to clean boards prior to soldering. You may need to use other cleaners if there is spillage or corrosion. After soldering clean the area again and clean the whole PCB after all sodering os complete. Cleanliness goes hand in hand with good solder connections. (if using Ultrasonic cleaning be certain liquids are 100% removed from the board before use or further repairs.)

  16. Use magnification to assure quality. Never rely upon 1X Vision, your eyes alone. Use magnifiers, endoscopes, or preferably a good microscope when working on Micro Electronics. You will never produce quality work if you can not see what you are doing clearly.

WHAT I DO... I try to keep an eye out for anything that can be damaged and protect it prior to soldering and clean everything. I use a heat of 350C or 662F for most things soldered by iron, For heat absorbing components and larger areas I will move my temperature up to as high as 400C OR 752F. Being QUICK IN AND QUICK OUT (after wetting occurs) is more critical than how much heat the iron is set at. I always use solder flux, there are three types of flux inactivated, mildly activated and activated flux, selecting the right type for the job is essential for consistent success. When my solder iron tip size goes below 1/2 the area to solder or twice the area size I change solder iron tips. The rest of what I do you can find above and there are other things less important that have not been described above. you will learn those things with time, practice and study.

Final note: I arrived at my heat setting over time and work. Later, I also noticed the photos of quality equipment being sold. Surprisingly those sales photos were mostly the same setting I use for the majority of my soldering iron work 350C or 662F. My assumed take away from this observation is two-fold, manufacturers chose a temperature that will help prolong tip life and chose temperatures that they use during their own work. Seldom have I seen recommendations for temperatures from a manufacturer in an add. I believe they avoid this to keep from raising an objection and creating indifference with customers over this delicate area of concern.

Solder iron tips are very sensitive to prolonged high heat and excessively high temperatures. I never raise the temperature above 400C and try to keep it below 380C nearly all the time. Replacing solder iron tips can get expensive quick so taking care of what you have insures heat transfer is taking place at the displayed temperatures as well as preventing the heat from displacing the atom arrangement in the many alloys of metal used to create your solder iron tips.

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  • \$\begingroup\$ This is a really a great and thoughtful answer. The ALL-CAPS gives away your age, but it is apparent that this is the voice of experience speaking. Thank you for the insight. \$\endgroup\$ – automorphic May 9 at 19:28
  • \$\begingroup\$ Do you see any problem using 700F for all small component work? Or is 600F better to reduce the chance of heat damage to sensitive parts? (The Metcal cartriges quantize the temperature to 500, 600, 700, 800 F.) \$\endgroup\$ – automorphic May 9 at 19:33
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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

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