ELECTRICAL AND ELECTRONIC | INNOVATION
around 30 years ago by Henkel (when it was called Macromelt Molding), which itself is now raising the profile of its Low Pressure Molding technology for encapsulating electronic components in its Technomelt polyamide adhesive moulding compounds. Henkel says Technomelt LPM technol- ogy is increasingly being adopted for electronic components, power and industrial automation, HVAC, lighting, and also medical. It sees economic, process control, design and environmental advantages over potting with reactive resin systems and high-pressure injection moulding. The technology is said to be particularly adept at encapsulating discrete areas in complicated assem- bly where wiring is attached to a PCB or other rigid component. One reason for this is that Technomelt resins, which are all unfilled, are resistant to high stresses and at the same time very flexible. Matthew Hayward, Global Key Account for
Power & Industrial Automation at Henkel, says he sees Technomelt as being particularly well suited to high-mix low-volume applications where through- put is key. “The ability to apply this material only where it is needed is a huge benefit. This enables one to ‘skyline’ an application (encapsulating only the components that require protection), or to significantly reduce the weight due to substantially less material usage.” Polyamide moulding compounds developed by
Henkel are said to provide exceptional electrical insulation, as well as resistance to a broad range of chemicals, extreme thermal cycling across high and low temperatures, and vibrations. The internal electronics are fully protected against outside elements, including ingress of water and dust, and long-term UV exposure. Michael Otto, Key Account Manager Engineering Adhesives for Low Pressure Molding at Henkel, says: “Unlike traditional two-component reactive potting compounds, the polyamides used in the Technomelt LPM process are single-component thermoplastics, moulding cycle times are shorter, and there are no emissions of volatiles. Whereas conventional potting
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Demonstration model of customised sensor at different production stages: CAD concept (top left), after integration of the electronic components (top right) and as a finished demonstration model (bottom)
can take as long as 24 hours to complete, our process has a cycle time that can be as short as 30 seconds. An additional important environmental feature of these polyamides, and one that is increasingly appreciated, is that they are largely bio-based, with up to around 80% of their content coming from renewable vegetable sources.” An advantage of LPM technologies in general
over traditional potting systems is that they are much more economical in the amount of material they use in the finished part. In potting operations, the normal approach is to build a box around the component to be encapsulated, and then fill the box until the component is covered. With LPM as explained by Henkel, the component is placed into a mould that has a cavity geometry similar to that of the component, so that when the polyamide is injected, it forms a skin around the component that is more or less the same thickness at all points. This means that the amount of encapsulating material used per shot can be considerably less. The same, more or less, is true with X2F. Costs of mould production are relatively low, especially as they are often made out of aluminium, which is much less expensive than tools made out of steel used in high-pressure injection moulding. In recent years, additive manufacturing techniques have also been adopted to make the moulds. Henkel works in collaboration with partners manufacturing processing equipment around the world. Otto says: “Technomelt is a total system that
October 2021 | INJECTION WORLD 49
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