Case Study – PCB Fabrication

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Metal Backed PCB As A Structural Component

With the exponential growth of LED lighting, some innovative designers have realised the benefit of treating the IMS circuit not only as a thermally efficient interconnection, but also as a mechanical component.

It is possible, provided certain design rules are observed, to utilise the board as part of the case, as the ground plane, and even as a relatively complex machined part.

The key to this development is to work closely with the board fabricator to come up with a design which can be brought in at reasonable cost.
First in this process is to select the best aluminium substrate, both in thickness, alloy composition and hardness.

We often use 6000 series alloys (the “Aircraft Grade” beloved by the Shopping Channel) in thicknesses up to 4mm, but beware of alloys of US origin, which will only be available in Imperial thicknesses.

These alloys offer much superior physical properties, but at a penalty of lower thermal conductivity when compared with pure aluminium, however still vastly superior to fibreglass.

These designs can include complex internal profiles, with blind holes and slots at higher order of accuracy than on a conventional printed circuit.
Additionally, various forms of threaded inserts can be included, either Heli-Coils* or threaded PEM* studs, some of which can be crimped into blind holes.

The aluminium back can even be anodised and dyed black, providing enhanced heat dissipation with electrical isolation.

As can be seen, a bit of lateral thinking can produce an enhanced product with less parts, better reliability and a lower cost in use.


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