Overlay complexities

All right... the overlays... we mailed tons of vendors trying to get back on track after the problem with those expensive "stickers" they cheated us with.

And now we have a very confident and reliable guy who also speaks English well enough to talk about... problems.

We had considered these overlays to be unrelated to everything else. After all they're just thick stickers with a plastic coating, right? So we designed the plastic, went ahead with the mold, and then proceeded to send our design off for manufacturing.

But we're now told the holes are too close. The space between them (less than 1mm) is not sufficient to cut a place of polycarbonate - using whatever tooling - in such a way as to preserve its shape. The PC is going to break between the holes.

Our target specs (0.5mm thickness, < 1mm hole spacing) is not physically possible. We believe them because we've been told this more than once (though a lot less clearly, in Nanjing dialect).

Their suggestion is to oh, just go ahead and make the remote a bit bigger. Hmm not when we've already got a mold we won't! Plus the PCB's final and it's a matter of days before we take it to the lab.

Looking at the big picture this is actually not a huge problem. Their recommendation is to just use 0.25mm polycarbonate. However even 1/4th of a mm makes a BIG difference in the look of these overlays. 1mm gives the overlay that thick A/C remote look (perhaps a bit excessive). 0.5mm is standard in high quality electronic appliances.

The bad overlays were, in fact, 0.25mm polycarbonate according to them. But now we've got a sample of raw 0.25mm PC material and 0.5mm PC material. Neither are as soft as the bad overlays which casts some doubts on the former point.

This new manufacturer is saying there are many kinds of PC from different vendors and they will have different properties, so the bad overlays may in fact have been created with 0.25mm, bad PC.

So, proceeding with our usual care and perfectionism, we've agreed to try cutting a 0.38mm PC sheet. If that works we'll be done; the difference of 0.12mm is hopefully not too dramatic and we'll still achieve the nice glossy effect we were after.

If that does NOT work they'll make a 0.25mm sample but even in that case they will use higher quality PC and so we hope the overlays will still be hard and flat like this latest raw PC sample we've got in our hands.

Just a sticker heh?

To add to the complexity there are different cutting methods, die cutting, molding, laser... they said they'll use die cutting for the samples and that the difference between this method and other larger run methods cannot be seen by the naked eye.

So it's more or less problem solved, but we won't know for another week or so whether the remote will look unbefreakinglieavably cool or just pretty darn cool.

And we thought the overlays were going to be the easiest piece of the puzzle...

Lesson learned: next time check design with overlay guys before finalizing plastic design.

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