usb capacitive touch pcb keypad

Capacitive Touch PCB Overview

The PCB keypad has the capacitive touch sensor pads on the top side of the PCB and the necessary capacitive touch driver electronics on the reverse side. The graphic overlay is attached to the PCB with adhesive or mechanically. The graphic overlay material could be glass, lexan, acrylic or any other plastic of various thickness. The main requirement of the touch overlay is that it must be non-conductive. There are other methods of making "touch" work with metal overlays. If you are interested in this, please contact us. When the human hand is brought in close proximity to the sensor pads, the capacitance associated with the pad changes. This causes a change in the voltage measured on the pads. This change in voltage is registered as a button press.

Design Phase

First we will need to collect some information about your project so that we can suggest the appropriate type of keypad design. The best way to provide us this information is by answering this questionnaire. Don’t forget to attach your artwork or rough sketch to the questionnaire. If artwork does not exist, we will help you create it. The artwork is one of the most important pieces of information required to design a capacitive touch keypad. It dictates the buttons location, dimensions and spacing. The artwork can also give us the locations of indicator LEDs, mechanical fasteners and the overall mechanical dimensions. The PCB keypad will be designed using this artwork information. The answers to this questionnaire and the artwork or simple sketch will prepare our engineer for the first discussion with you. This first discussion will cover the following:

  • Determine the type of keypad that will work best
  • Confirm functionality and communication requirements (more info)
  • Answer any questions the customer may have and collect miscellaneous information needed to prepare a quote for the prototypes and an estimate for production

Prototype Phase

Once the quote has been approved and purchase order has been accepted, our engineers will start working with you to create your custom prototype keypad. The prototype phase includes the following:

  • Schematic Design - PCB Layout, release design to fab.
  • Print and assemble graphic overlay
  • Assemble / Solder PCB Components with our pick and place equipment.
  • Software - Configure and Tune keypad
  • Test capacitive touch interface system (preferably in its final resting place)
  • Capacitive touch panels are very sensitive to interference caused by the surrounding electronics. Therefore it is important that the prototype keypad be tested in a fully assembled functioning product. Our tools can help identify noise that is generated by the surrounding electronics. The information collected during these tests can be used to make the system more robust. It is also important that the buttons sensitivity be tuned to the correct fascia material and thickness. We prefer having a full functioning unit to test and tune the capacitive touch keypad. If this is not possible, having the parts that are closely related to this touch panel will help a great deal.

  • Deliver 1st article prototype for approval

Once the first article is approved, the remaining prototype units are built and shipped.

Based on the approved article we generate the final bill of materials. From this bill of materials we can now quote the true production cost.

Production Phase

Once the production quote has been approved and purchase order has been accepted, we prepare for production. An accurate delivery schedule will be available once we order the production materials / components from our suppliers. We will develop a test fixture that will be used to comprehensively test each of the assembled touch panels. We will also manage each step of production to ensure there are no unnecessary delays.