Industrial + Specialty Printing

(March 2010) posted on Mon Mar 29, 2010

The membrane-switch market has experienced dramatic growth and soared to an unprecedented level.

By Mike Young

• 
• 
• 

For the longest time I equated the printing of graphic overlays and membranes to an electronic-graphic application, meaning it had a combination of two- and three-dimensional prints, high-end graphics and conductive layers. While this view has not changed, the actual marketplace has since experienced dramatic growth and soared to an unprecedented level in respect to quality and the number of players who want to produce membrane switches. In a sense, it is still a graphics-based product with a kind of printed-circuit-board mentality in its fabrication—fundamentally the reason why some of the processing steps in prepress, printing, and finishing may have to be fine-tuned accordingly.

A few short years ago about two-thirds of graphic-overlay printers did not fabricate the membrane layer themselves—essentially, not building the switch as a whole. Today, the percentage of overlay-only printers has changed radically as more companies want to produce the membranes in-house and others, who were once generally categorized as decal, label, or nameplate printers, are also knocking on the door to find their piece of the action. While the economic aspect behind their reasoning to venture further into this market is understood, many are finding it a little more difficult than first imagined—at least from the perspective of screen printing.

Producing overlays (Figure 1) requires a high level of competency throughout the screen-printing process. Screen printing is essentially a two-dimensional process, insofar as the letter E, for example, has height and width when printed onto a flat substrate. On the other hand, the integrity of a conductive print requires a three-dimensional feature because it must have a certain deposit thickness and profile in support of electrical properties for the finished product to function properly.

Ink thickness is not specified for an overlay, though proper opacity is understandably a must to prevent light from leaking through. However, conductive prints must meet defined mechanical specifications and electrical properties, thereby not only taking the process of screen printing to a higher level, but also into a world of industrial/electronic printing. The transformation from overlays to membranes is not difficult to achieve providing the producer realizes that the end results do not happen by chance.