nein

A 9 key macropad

Powered by a Pro Micro and can fit any of the various different sized variations of Pro Micro.
Each switch is connected to it's own data pin and ground. There is no need for diodes, as each key has a dedicated data pin there is no possibility of ghosting.

The pinout is:
     F4, F5, F6
     F7, B1, B3
     B2, B6, B5

In Arduino the pin numbers are:
     21, 20, 19
     18, 15, 14
     16, 10, 9
The board can be flipped so that the Pro Micro can be mounted right side up, or upside down.

Gerber files on Git. There is also a json file for kbfirmware.com.

Assembled board with some left over Stealth G20 keycaps.

Low profile Peel-A-Way sockets. There is a place for a 5.2mm surface mount tactile switch connected to the RESET pin.

A standard Pro Micro will fit on the two inner rows of pins. 

The larger Pro Micro with the Mini USB connector fits on the outer rows of pins.

The odd ball Pro Micro is half way between the regular and large Pro Micros. It will fit on an inner and outer row.

PCB bottom.

PCB plate, PCB, and bottom assembled with M2 Spacers and screws.