CASE STUDY - Keypads Case Study

How Melrose engineers fixed equipment failure due to moisture ingress?

Our client – a leading company in the at-home beautify devices market – approached us with a problem that users experienced in one of its products. The company’s distributor received complaints from customers who reported that the device failed to operate over time.

Melrose engineers identified the root cause of this problem, proposed a short-term solution, and delivered recommendations for long-term improvements.

The Challenge

Our client was a company responsible for designing and manufacturing a skincare device.

The product included a plastic housing and a membrane switch with a control keypad (on/off), vibration speed, and displacement. Due to the product’s use cases, the keypad was regularly exposed to condensing moisture (but not submersion).

Designed by another supplier, the keypad presented an issue as the client’s distributor began receiving complaints from consumers who noted that the device failed to operate over time.

Our Solutions

Our client asked Melrose engineers to evaluate the components behind the product’s failure.

Upon examination, our team noted that the conductive silver traces spread across the conductive silver membrane switch tracks caused by the growth of crystalline dendritic structures. This phenomenon is known as silver migration.

Silver migration occurs when membrane switch traces are exposed to moisture. It’s the ionic movement of silver between two adjacent traces, inevitably resulting in an electrical short. We have seen this is happening in many types of products and across various industries, commonly in printed electronics, microelectronics, components, PCB assemblies, and membrane switches.

Melrose engineers used submersion of the device in a shallow water bath with dye. Tracing the path of the colored water, it became clear that moisture was entering the device through the point where the membrane switch tail entered the housing as the device. The design incorporated a “tail filler” instead of a complete gasket around the part perimeter.

Results

The Melrose team proposed a short-term correction to the problem in the form of RTV silicone adhesive applied to the tail exit location when the product was assembled. The next-generation plastic molds allowed the development of a fully sealed membrane switch gasket.

Our team helped the client solve the issue successfully and offered a reliable recommendation for the future to ensure that the product delivered the best user experience.