Drag soldering, liquid flux is a must-have. Sure it is, but what kind? Well, that was a tough question to answer from the looks at fist, but now, the answer is clear. If you want to solder small, miniaturized, high-density electronics, then no-clean flux is your go-to kind of flux, especially if you are doing new board work rather than repair on old boards. Okay, that makes the decision really easy for the sake of my own projects.
20200728/DuckDuckGo what kind of flux works best for drag soldering
This website also has a lot of other great information on your choice of solder flux. In particular, when working on old boards, you should use Rosin Activated (RA) flux because the stronger flux will more quickly clean away oxides that have built up on the board.
20200728/https://www.pcbtoolexpert.com/the-top-5-best-flux-pens/
Another good point mentioned in the article. Do you need flux to solder? If you want to do soldering right, yes. Otherwise, you will vaporize metal oxides, and trust me, you don’t want to be breathing those in. Yes, that’s interesting that flux helps prevent metal oxides from going airborne.
Wait, what? I heard mention of making your own solder flux? Okay, okay, let’s see how that works.
This first YouTube video, it doesn’t really go about making your own flux, but rather it demonstrates how you can make a liquid flux from a tacky flux. Mix the tacky flux with isopropyl alcohol, then let sit overnight, the tacky material will be dissolved and you’ll have your own liquid flux. What? Are you kidding me? That stuff is flammable. Okay, okay, but as I discuss later, this is actually rather temperature-resistant. Also, as the author states in the video, he likes his liquid flux made with isopropyl alcohol because it is more resistant to evaporation under high temperatures than conventional liquid flux.
The YouTube video also showed a good example of how to use flux to help you with desoldering. First you get flux around the chip to desolder, then you use a narrow-tipped heat gun on the chip, and then after a while, you should be able to pull the chip off the board with a pair of tweezers. Wow, this trick was even demonstrated on BGA packages, very impressive.
20200728/DuckDuckGo make your own soldering flux
20200728/https://www.youtube.com/watch?v=9xk76e7nzcw
Okay, here we go. How to make your own flux. Here, they just find some pine cones, cut off the “leaves,” then use ethyl alcohol to absorb the sap. This is then distilled through some coffee filters. Okay, okay, but you’re still creating flux out of flammable chemicals here.
20200728/https://www.instructables.com/id/Make-your-own-Eco-friendly-soldering-flux/
Don’t worry too much about isopropyl alcohol, though. The autoignition point is 399 degrees Celsius, so long as you keep all your equipment below that temperature, you should be fine. And what about ethyl alcohol? That autoignites at 363 degrees Celsius. So, ethyl alcohol is not as safe to use as isopropyl alcohol.
20200728/https://en.wikipedia.org/wiki/Isopropyl_alcohol
20200728/https://en.wikipedia.org/wiki/Ethanol
20200728/DuckDuckGo ethyl alcohol autoignition
20200728/https://www.engineeringtoolbox.com/fuels-ignition-temperatures-d_171.html
So, what resulted in my soldering iron tip getting? I’m pretty sure it was the fault of solder flux. Namely, the flux coating on my solder wick. That seemed to be where the most aggressive treatment was coming from… the solder wick is so effective at sponging up solder that it will always sponge away the solder right off of my tinned tip, then I have to go about retinning it, always. Not to mention that the solder that flowed into the solder wick makes that part of the solder wick no longer usable for wicking up more solder.
To add insult to injury, because the solder wick is also flux coated, the de-tinned soldering iron gets exposed to flux, too, decreasing longevity at the soldering iron’s tip due to the deliberate mildly corrosive properties of solder flux.
Also, actually there’s another issue, maybe more suspect than the solder flux. The fact that I was using a paper towel as my solder sponge meant that sometimes bits of the paper towel would get stuck to the soldering iron and burn… and therefore leave behind contaminants that could speed up corrosion on the surface of the soldering iron.
Okay, okay, I think I get the idea. All of these ill effects together are what contributed to my problem of growing corrosion on the tip of my soldering iron.