A tiny screen loses some of its advantage if the connectors take up almost as much room as the display. I used castellated pads and 0201 passives to keep this 0.42-inch OLED assembly compact.

The display has 72 × 40 pixels in an assembly measuring 12.6 × 13.3 × 2.4mm. That makes layout a real design exercise: a few characters, a clear icon or a carefully drawn animation can use the space better than a crowded interface.

Castellated connections let the module become part of a custom PCB without a tall row of headers. See the documentation below for the electrical interface and display setup for this module.

Documentation: https://www.questwiseventures.com/products/extreme-miniature-0-42-oled-72x40-display-screen