A lot of prototype circuits used to be lashed up in this way, back in the days when things generally ran a lot slower and one could get away with air-wiring a circuit with no ground plane. The late, great Bob Pease was a fan of this technique, and for high-speed and high-precision circuits he’d wire together the components above the copper side of a blank PCB and use the copper foil as a ground plane:
What’s All This Pease Prototype Stuff, Anyhow?
I’ve a similar technique for surface mount components, where I stick the SMD parts to the insulating side of a bit of single-sided PCB, wire them together, and drill little holes whenever a ground connection is required. It’s great for things like simple switched-mode power supplies that are sensitive to component layout and grounding technique. Most people mount their chips in the dead bug fashion (i.e. legs in the air) as it’s easy to tack them down with a blob of glue, but I prefer to put ICs the right way up as I want it to be more representative of a PCB layout.
The master of the art of air-PCBs was Bob Pease’s close friend, the also great, and sadly also late Jim Williams, who did go out of his way to introduce an artistic aspect. Here’s a thermometer, which works by measuring the speed of sound of air in a jam jar (it’s the one with the parrot):
Remembering Jim Williams, 5 years later, with the engineering behind it in the white paper “An Introduction to Acoustic Thermometry”
I’m a big fan of flux, me, and I wish I’d had cottoned on to its awesomeness years before I did. I am grateful to the excellent technician colleague who enlightened me. Lead-free solder is not as easy to solder with as the old, toxic PbSn types, but a bit of flux works magic - just remember clean it off afterwards as it can be corrosive in the long term. Decent lead-free solder helps a lot; I’m a fan of Stannol HS-10 (another top tip from a technician colleague - they’re worth their weight in gold, good technicians). I prefer the old-style rosin solder, which has fallen out of favour with most PCB assemblers due to the need to clean it off afterwards. I hate no-clean flux (which is the preferred type these days) as the faint residue it leaves behind is very difficult to clean off, and it’s also very slightly conductive; not a problem for most circuits, but can cause big issues on sensitive high-impedance/low current designs. The right solvent will shift it though, and I’ve had excellent results with Flux-Off No Clean Plus from Chemtronics, and it works extremely well with rosin fluxes too. Flux-Off do a rosin-specific solvent, but I find the No Clean Plus works for everything (fluxes, sticky labels, gum, ink etc.).