it's for electronics, so needs to have rosin inside, looking for around 1mm or thinner, the one I'm using now is made by weller in west germany, by far the best quality solder I have used, can't find any thesedays, I bought it in 2012 on amazon last time.
Have you ever tried using lead-free solder?
I switched to it some years ago for most work. Still use leaded solder for some repairs, for which it is still legal to do in the EU. There are some very vocal folk who do not like lead-free stuff, but I haven't had a problem with it personally.
It is probably time to move on from leaded solder; it is still widely available and can be used in some applications but for most things, unleaded will do. If you are struggling, you might have more joy with a solder composition like 97.1, 2.6, 0.3 Sn, Ag, Cu, which is a eutectic alloy with a slightly lower melting point than the more common (and cheaper) 99C tin/copper alloys, so less prone to dry joints through movement during cooling, and pick a fairly active flux like Kristall 400 or 505.
A lot of the troubles with lead free solder are down to not hot enough iron - needs to be ~40-50C hotter, and selecting fluxes intended for low residues / no clean soldering of brand new, shiny clean, PCBs and parts.
naah, I'm sticking with tin/lead solder thanks, already ordered some.
I'm not really asking for advice on what solder is better, I like my 25 watt antex iron which works so well with lead solder, it's not hot enough for unleaded stuff and I don't want to get a new iron just for that.