Epec's Blog | Electronics Manufacturing Solutions

As a leader in user interface technology, we frequently get asked the question, "What kind of user interface is the best option for my application?" User interface, or Human Machine Interface (HMI), assembly designs are dependent on the application, housing, and the environment they will be used in. Choosing the right option and material is a key component.

Packaging for user interface assemblies is the last step in the manufacturing process, but not a step that should be rushed. Epec pays as much attention to packaging detail as we do to design and manufacturing of custom assemblies. Because each assembly part number is customized, each has different size, mass, and shape. However, styles of user interfaces can be grouped into several categories. Experience has shown the type of packaging that works best is based on complexity of construction, shape, size, mass and shipped unit volume. No one packaging solution works for every assembly style.

This blog post addresses custom user interface testing in terms of functional test schemes that are completed prior to shipment. Generally, the first user interface assemblies shipment are for First Article acceptance testing where customers fully examine the first units for mechanical and electrical compliance to all engineering drawing and specifications.

The need to protect your keypad from the ever-present threat of wear-and-tear is crucial for all applications.  If your control panel is going to be used in marine environments, medical devices, or other consumer electronics, the threat of water or liquid exposure is ever present. In wet situations, it is critical that all electronic components are completely sealed off from any outside substances that could damage the device.

Many applications would be better suited using a membrane switch (low profile, flat surface keypad assembly) along with a rigid printed circuit board (PCB), replacing screen-printed silver conductors on polyester sheets.

Printed circuit boards with gold plated switch contact pads and gold plated dome switches greatly improve the reliability of your application, offering longer operating life with lower switch resistance and contact bounce.

The smallest bend radius that can be used on a membrane switch tail will depend on the type of design. Deciding factors will depend whether or not the user interface is constructed with one tail/circuit layer or dual tail/circuit layers, and where the bend is located.

Custom low-profile keypad assemblies used in OEM applications incorporate snap-acting dome switches. Dome switches are a type of keypad assembly switch intended for very long cycle life and years of trouble-free use but are intended for logic-level switching, not power switching.