MMi203: Graphic overlays
You will find dimensioned drawings of our universal graphics overlay on the Resource Kit CD under the File Resources folder. They are there in several formats. You can use those as a starting point for creating your own labels. Please contact us if none of the formats there are suitable for you, and we will try and generate a mutually agreed format (if we have the right software to do so).
The picture illustrates how the universal overlay supplied with -DK (Developer's Kit) versions works. The overlay has clear windows placed next to the switches and buttons, plus one larger window (not shown). The idea is that you make yourself a self-adhesive paper label on an inkjet or laser printer, stick that onto the metal panel and then stick the plastic graphics overlay down on top. Make the paper label just large enough and no larger, so the plastic overlay seals it all around.
If you are going on to make (or have made) your custom overlays, you will need to design your own artwork. Unless you have already been through that process, you are well advised to start by first locating a screen printing company to do your printing and consulting with them on suitable artwork formats. Don't do the artwork first and then look around for a printer ... you will most likely find you have been wasting your time.
Another word of caution: If you use a graphic artist to design a snazzy overlay, watch out for two things:
- Graphic artists tend to ignore considerations of cost. More colours equals higher cost
- Some graphics artists have no idea about making dimensionally accurate artwork.
Some companies are now offering a service making prototype overlays for a very reasonable price.
It is also possible to make quite good looking overlays using an ordinary colour inkjet printer. You can print on paper and get it laminated, or rear print on transparency film. Either way it helps to get hold of a supply of double-sided adhesive film. If you make your own for prototypes keep in mind that a subsequent production screen print can only have solid blocks of colour (spot colours), not blended and graduated colours (process colours).
If you are making a large number of custom overlays, consider having domes heat-embossed over the push button switches. This will look better and also reduces the tolerancing requirements of the board to panel spacing.