If you order a “Wemos D1 Mini” you’d expect to get the same thing every time, right?
The Wemos brand has become a victim of counterfeiters, who make a near-exact copy of the board and then produce it as cheaply as they can. These two D1 Minis look superficially similar, and if they were lying on the bench you would probably have trouble telling them apart:
But look closer. The shape of the PCB is slightly different around the top edges, and the silkscreen is slightly different. It’s most obvious around the “5V” label near the bottom left. There’s also slightly different soldermask pullback around the pads. The board on the left has several parts out of alignment, although electrically they’re still connected and the board works fine.
Part of reducing the cost is to use whatever is the cheapest PCB substrate they can get their hands on at the time. These D1 Minis were made using totally different PCB material:
One PCB is 1mm thick, and the other is 1.6mm.
I’ve seen D1 Minis with 0.8mm, 1.0mm, 1.2mm, 1.4mm, and 1.6mm PCBs! You really can’t predict what you’re going to get.
Why does this matter?
Most of the time, it doesn’t. But recently I heard from someone trying to build my Air Quality Sensor project that their D1 Mini wouldn’t fit in the 3D printed case, because the case only allows PCBs up to 1.2mm thick! Oops.
So I’ve now generated STLs for both 1.2mm and 1.6mm slots, for both the “Basic” and “Display” versions of the case. You can grab the latest STLs from the product pages, linked from the respective episodes: