I have been experimenting with different kinds of solder for use in audio. My experiments have all been on cables but presumably it affects PCBs as well.
I mostly use 60/40 leaded solder. IMHO all the lead-free stuff is crap, takes too much heat to flow properly and make a really good join plus the fumes are worse than the leaded stuff. There is still some variation between types of leaded solder though.
The main type I use is Goot SE-06008 as it flows well but is also malleable enough to make bridges when doing matrix board or cable joins. It is 60/40 183-190C 0.8mm multicore I believe with flux built in. I also tried some Goot SD-60 which has much more flux and consequently is more "wet" and hard to make bridges with. It flows very easily and is good for making very "close" and minimal joints. The SD-60 is designed for SMD work so is not ideal for making cable joins from an ease-of-use point of view, and I am still in two minds about the sound quality. I think a good metal-on-metal joint with SE-06008 is superior most of the time which I think could be down to the SD-60 working in between everything and thus forming a layer between the two surfaces. On the other hand in situations where it is hard to make that type of connection with normal solder such as wires direct to SMD ICs it might be better.
I suppose it really depends on the application then. I also have some Almit KR-19 which is 0.65mm and less wet than the SD-60 but still quite clingy. It is easier to work than the SE-06008 but seems not to make as good joints, but I have not done any ABX testing so it may just be the result of inhaling whatever they put in it... Seriously, it smells floral!
Anyone else noticed any differences between types of solder?