New technique for moulding flexible PCBs

2nd April 2017

Peter Smith

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Model Solution has created a unique manufacturing solution for a company trying to validate the mass production potential of its wearable device design. The Myo armband from Thalmic offers touch-free control of technology with hand gestures and motion. Via a wearable presentation remote, the Myo gesture control armband reads a user's muscle activity and hand motion to control presentation software.

Thalmic needed to prove the touch free controller could be manufactured at a reasonable cost. To accomplish this task, Model Solution has developed 14 individual tools used to generate the production run, including a new method to hold flexible PCBs in place while moulding around them.

The Myo device contained a long flexible PCB that was very difficult to work with because it did not have the restitution force necessary for efficient assembly or injection moulding. Choosing suitable materials to be used in the injection moulding process also proved difficult. The wearable device also needed to utilize a flexible, yet rugged material to provide a comfortable user experience with high reliability.

Model Solution worked with Thalmic's design team to utilize insert moulding and sub-overmoulding techniques that enabled the creation of a thin flat FPCB that could be curved into a U-shape, increasing its force of restitution. After selecting a suitable material, Model Solution was able to draw upon its advanced quick-turn tooling capabilities utilizing a combination of semi-automatic and manual tooling to produce the production run.