What is the best temperature for soldering electronics? This is a question that often puzzles many electronics hobbyists and those who just start learning soldering. Before start answering that question, there area three things we need to clarify.
A few things to understand
1. Heat Damage of Electronic components when solder
The components get heated up too much for too long when we try to heat up the connection in order to melt the solder with the soldering tip.
2. Electrostatic discharge (ESD)
When solder, heat is not the only one that can damage sensitive electronic components. Electrostatic discharge (ESD) is another major killer for electronics ICs. ESD wrist strap only cost a few dollars. Do not forget to buy one and wear it when you solder.
3. Proper solder tip size
A common mistake for beginners is to use a soldering tip that is too small. In that case of soldering two piece of thick wires, setting soldering tip temperature high does not help since it takes long time to transfer the heat from small size tip to the connection where we need to solder. Vice versa, soldering small SMD components are also not recommended. In that case, the heat transfer too fast lot of times. So, to use proper size solder tip is the first step for successful soldering without damaging the components. For more details, please check this article.
4. Solder melting point
60/40 or 63/37 leaded solder melts around 185°C or 370°F. The melting temperature of the lead free solder is about 5~20°C or 40~68°F higher.
What is the best soldering temperature?
To solder a connection, ideally you want to quickly heat up the connection to melt the solder wire before ICs or electronic components get heated up. So, you will set soldering temperature higher than the melting point of the solder you use. But, what is the best soldering temperature? The rule of a thumb is to set soldering tip temperature 100~150°C (212~312°F) higher than the melting point of the specific type of solder you use. In my case, I use the regular 60/40 solder for the soldering work more often than lead-free solder wire. So, I often use two temperature settings, 325°C(617°F) and 375°C(707°F). 325°C is for regular job with leaded solder. 375°C is for the solder work with lead-free solder. Once a while, 375°C temperature setting is used to solder bulky components or something heavy even with leaded solder wires.
No temperature readout?
Not all the soldering stations or irons have direct soldering tip temperature readout on the panels like Weller WESD 51 and Hakko FX 888. If you own soldering stations that do not have temperature readout, you can use the following k-type thermometer to measure soldering tip temperature with different output power setting. It also works if you already have a multimeter at home, you can just buy K-type therm couple. If you do not understand how K-type thermocouple, please check out this post.
Basic principal to follow
To avoid the components from being damaged by heat, what you need to do is to heat up the joint quickly with the proper temperature setting, flow the solder into it, and then leave. Never leave soldering tip on component connection on circuit boards for any longer than necessary. It takes some practice. But, the minute you get it, you will not forget. It is kind of like rice cooking . You do not want to open the lid to look during the process of cooking rice.
One extra tip. Every soldering station has its own thermal recovery characteristics for solder tips after every connection is being made. Good soldering stations have fast recovery time. The preset soldering tip temperature is different from the actual transient soldering tip temperature. You need to consider this if you do a lot of soldering.
As discussed, there are a few different factors you need consider for optimal soldering temperature. But, I believe you’ll soon realize that only a few soldering work is bound to expect you to make changes to temperature settings. In my case, I mostly use 325°C(617°F) and 375°C(707°F) for my soldering work. That is my best soldering temperature. If you have further question on this topic, please let us know.