Pad card

Provided by the ASK Keyboard Dictionary

Aka/also known as: capacitance-sensing PCB, capsense PCB, capacitive PCB

A pad card is what IBM called a PCB with contacts to facilitate capacitance sensing. The name likely refers to the appearance of many pairs of rectangular pads of exposed copper under each key-switch actuator. Whilst pad cards may have controller/logic electronics on them, there is no specific requirement for one to also have such 'brains'. Some pad cards even had an edge connector for slotting a controller card onto it. IBM Model B and Model F keyboards both made use of pad cards.

Sources

ASK. Admiral Shark's Keyboards original content. License/note: CC BY-NC-SA 4.0.