Jim, AFIK the LCD display manufacturers don't have a problem with ESD (although I don't think they test to the level to which you are subject). Most notebook computers don't even have a plastic window covering their LCDs. Most calculators or clocks don't either. How thick is the top layer of your membrane switch/window? I believe that if you have sufficient thickness in this part, you won't have an ESD problem. Then again, I haven't a lot of experience with either membrane switches or LCD displays, so all I am going on here is a hunch...
Steve Chin StreamLogic Corp. Menlo Park, CA, USA sc...@streamlogic.com jeich...@statpower.com (jeich...@statpower.com) wrote: > >I am looking for some guidance on the following construction: > >We have a remote control panel that contains an LCD display (approx. 2" x >1") mounted on a circuit board behind a metal panel. An opening in the >metal panel allows the user to see the screen, and is only marginally larger >than the display. Over the metal panel is a laminated label containing some >membrane switches. All the circuit traces for the membrane switches are >approx. 1/2" or more from the edges of the label, and are contained in the >bottom layer of the label (ie one layer of plastic between them and the >metal panel). The ribbon cable from the membrane switch to the pwb is >routed through a hole in the metal panel. There is a clear plastic window >in the label allowing viewing of the LCD and that window is more or less >touching the glass face of the LCD display. We don't want to recess the LCD >because of viewing angle problems. > >We are subject to 8kV air discharge and 6kV contact discharge. > >1. Does this construction sound like an ESD test failure waiting to happen? > >2. Does it make any difference whether or not there is an air space between >the clear plastic window in the label and the glass face of the LCD display? > Should we recess the LCD, and if so, by how much? > >3. Are there preferred materials for any of the layers of the membrane >switch label? > >4. Any hints anyone? > >Any help will be greatly appreciated. > >Thanks, > > > > >Jim Eichner >Statpower Technologies Corporation >jeich...@statpower.com >Any opinions expressed are those of my invisible friend
