Enclosureless cases: when the PCB stack is the enclosure
Three PCBs, one perimeter solder joint, no injection moulding. Our utility model DE202020106111U1 for sealed, EMC-shielded sensor housings.
A sensor node costs five euros in components. A plastic enclosure for it costs tooling, a second supply chain, assembly steps and space. At low volumes none of that amortises. With many measurement points it adds up.
Our answer, filed as a utility model with Odin Holmes in 2020: no separate enclosure. A bottom PCB with mounting tabs, one or more frame PCBs with a cutout that define the cavity, and a top PCB carrying the electronics. The layers are joined by a continuous solder joint around the perimeter. That joint seals against moisture and dust and, as a closed metallic loop, doubles as the EMC shield.
The advantage is in the supply chain: PCBs arrive in days for a few euros each, an injection mould does not. Height and volume scale with the frames, and assembly stays an ordinary reflow process.
We use the principle in sensor projects and advise on it as part of PCB design. How the solder joint becomes reliable in reflow, and where the limits are, is described in the blog article.