Waterproof Handheld Device Design

Waterproofing a product can be a difficult goal to achieve.

Waterproof products create unique design challenges development of a waterproof enclosure is not an intuitive process. If you haven’t been successful at doing it before, it is very difficult to execute successfully.

Waterproofing was only one of the challenges

A careful look at the design revealed a number of areas where we could help. First of all, it was clear that the proposed design would not pass the underwater immersion requirement. The seals would have to be redesigned, the case was too flexible for long-term integrity, and the way the two halves of the case joined would have to be changed. Beyond waterproofing, there was a manufacturability question regarding the placement of an infrared lens in the case.

We re-configured the o-ring seal, incorporated some internal shock mounts, and provided interlocking features to stabilize the pager-sized case. Our Mechanical Engineers worked with the customer’s vendors, and redesigned the way the I.R. (infra-red) communication lens installed so the device would be manufacture-friendly.

A major issue was the two circuit boards and placement of the specified components.

It turned out that we weren’t done yet! When our designers looked at the proposed double-sided circuit boards we saw that they were too thick to fit inside the handheld case. To accommodate the boards as the original electronic engineers had envisioned, the eventual case size would need to be 50% thicker than originally planned. The entire case would need to be redesigned if we couldn’t find a solution.

We reasoned if we could modify the placement of the components, maybe we could “nest” the double-sided companion boards to eliminate the extra thickness. Our approach was to solid-model the boards and their surface-mount components.  In the computer we could test different placement schemes to see if there was really room to nest the components without physical interference.

We combined 3D printing and electronics

During this process we had ongoing communication with our client company to make sure the proposed placement changes would be okay. When we believed we had the solution, we tested the design changes by building 3D printed models to confirm the fit. See picture at left. The next-generation boards were configured with the components arranged as we suggested.

In the end, we achieved the goals of our client company. 

The surface-mount boards fit closely together without any contact between component leads and traces. The result was a densely-packed product, within the target size range. The device passed waterproof testing on the first round. It is doubtful this project could have been done in the available timeframe without the power of solid modeling and rapid prototyping methods.