A cage for a camera device. Sure LOOKED sturdy, till the cruddy solder/flux “paste” failed. I shoulda just soldered them the classic way.
60/40 or slightly better 63/37 (eutectic) solder for electrical work is widely available, in
electronic supply stores. If you get the rosin core type (I like Kester-44) you don’t need
any additional flux…just reasonably clean conductors. The cooled rosin is non-conductive,
and non-corrosive, and pretty tenacious unless you use now-banned solvents. No reason to clean it off except for appearances. So called “no clean” varieties that contain less flux…which may produce an inferior joint.
If you get some “organic flux” type, you DO need to clean the residue off, which can be done with water and dish soap.