Low-pressure molding as a method of enclosing consumer electronics

Low-pressure molding is a relatively new process (to North Americans) that aims to encapsulate sensitive electronics using a polyamide material. The process was discovered in Germany in the 70’s as a result of the observed effectiveness of using hot melt glue (a polyamide) to strain relieve electrical connections on printed circuit boards (PCBs).

The difference between this process and the ever so ubiquitous injection molding is implied in its name; it occurs at low pressures and as such induces significantly less strain in fragile soldered connections. Polyamide materials also tend to melt at temperatures a few hundred degrees lower than typical injection molding materials, which means they do not heat up the PCBs to the point where solder begins to reflow or melt. As a result of this, PCBs can be directly insert molded (or over- molded) using Low-Pressure Molding, as opposed to the typical clamshell + assembly process used with injection molding.

Polyamides can also be made quite malleable, and as such over molded enclosures can include built-in strain relief which is typically a separate part in injection molded enclosures. This simplifies design and manufacturing by requiring one less part to be sourced from china and one less part to be assembled during production. Polyamides also have the benefit of being optically transparent by nature, so any status LEDs that may be on electronic devices will shine through without much thought by the designer.

Low-pressure molding is also quite attractive from the perspective of someone looking to bring their enclosure manufacturing back in-house from overseas. Machines can be had for comparatively low prices (to injection molding machines), and each low pressure molded enclosure could be up to 0.2$ cheaper than the equivalent injection molded enclosure when the cost of add-on strain relief and shipping from china is considered. Low-pressure molding also has the benefit of being fairly straightforward to prototype, as any hot melt applicator that can be fed bulk hot melt can be used with silicone molds to produce a fairly faithful version of the final product at a cost quite low when compared to that of a prototype mold.

Lava is investigating the technology, and it could be used to encapsulate a future product.

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