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Project Description

The customer was receiving complaints regarding the failure rate of a membrane switch keypad used to control their automated beverage system. Our capacitive touch keypad must be a drop-in plug-and-play requiring zero modifications to their existing machine.

Membrane switch technology has a button press cycle life. This means that the keypad will fail after a certain amount of button presses. Its layered designed is weak and fragile when used in highly repeated and frequently used machines.

Why use capacitive touch?

Capacitive touch design is extremely robust, it is usually made of a glass or plastic overlay and a PCB. There are no moving parts. Customers have tested our keypads MTBF (mean time between failure) and have found that our keypads can last over 120 years before failure.

How we reverse-engineered the old membrane keypad?

The requirement forcing our capacitive touch keypad to drop-in and plug-and-play with zero modifications to the existing machine required us to reverse engineer the old membrane keypad and its interface with the machine. Several bench tests were done to prove out the new control interface. Once we had a working design the capacitive touch keypad schematic was designed and the PCB was laid out.

After the PCB was designed, a 3d model was exported from Altium designer into SolidWorks. In SolidWorks we designed an injection molded bezel that would mount the keypad to the machine. The first 10 assemblies were 3d printed and sent to the customer for field testing. After receiving approval from the customer, molds were made and the bezel was injection molded.

Project Details