For most of my soldering life, I still use what we call as ‘Flux’ or ‘Soldering Paste’ (or also known as ‘Lotfett’). Although some people say that the use of Flux for soldering is for newbie work ;), but I don’t really care actually. What I do want is a perfect soldering quality.

Below is the frequently used Flux. It’s cheap (indeed, very cheap) and enough for most of us. I bought this long-long time ago and never can finish it although has been used hundred (if not thousand) times.

But few weeks ago, I started to think a better replacement. I saw a Rosin Flux made by Cardas (to be honest, not many brand makes such Flux any longer as most of the newer solder already incorporates Flux inside to simplify our soldering job). But again, in most of the time, a separate Flux still needed. As the price was quite reasonable (though still multiple times compared to the Lotfett), I decided to grab one.

Below is the example of excessive usage of Flux. At one side, it can help you to make a very good solder joint and a perfect (well rounded) appearance. But at the other side, it will leave some residue. See those ‘black markings’ surrounding the solder joint. Most of the time, this residue might not be very dangerous. But on some certain ‘Flux’, this residue could lead into a corrosion of your solder joint. I also hear that this residue could lead into some small ‘short’ on some sensitive circuit.

So the best way is to clean them up 🙂 See below. You can get a perfect quality soldering (an ideal ‘ball shape’ solder joint) and with some extra cleaning job, you can remove all those residue. You need some thinner or similar cleaner to do so. Meanwhile, please make sure your PCB has good quality, otherwise this kind of cleaner could ruin the painting on your PCB.

Accidentally, the seller of the Cardas Rosin Flux sent me 100 gram of Cardas Quad Eutetic Solder instead of my Rosin Flux on the first shipment. Well, instead of sending back the Solder, I decided to take this to have a try;)

So at least I have 3 famous Solder on hand now: 250 gram of WBT (leaded), 500 grams of Mundorf MSolder Supreme Silver/Gold (non-lead), and 100 grams of Cardas Quad Eutetic (leaded). Thinking to grab some Audio Note to, but they are selling in 500 or 250 gram only (well, currently I got nearly 850 grams of tin on hand in 3 various brands. I don’t see the reason to add more that much –  at least for now). Thinking to sell some to, as I really don’t need that much 🙂

And probably I will arrange some comparison later… Again, such a lot of toys, such a limited time…