Lens choice helps, but the key factors are space, distortion, and resolution. For a flat subject, use a lens with low distortion and good edge-to-edge sharpness. A macro lens is often a strong choice because macros are typically very sharp across the frame and have minimal distortion.

If you have plenty of room, stepping back and using a normal-to-short-telephoto lens can reduce perspective and make the board look more scan-like. If space is tight, use whatever focal length fits the board, then correct any distortion in post.

If you need more detail than a single frame provides, use multiple overlapping shots and stitch them into a panorama/composite. Shooting several images with a longer lens can give you a much higher-resolution final file than one wide shot.

So: the “best” lens depends on your working distance, but prioritize low distortion, flat-field sharpness, and enough distance to keep geometry clean. A macro lens in a normal/short-tele range is a good starting point.