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Membrane Switch (keypad)
Design and Specifications
1) Design Files:
Please provide mechanical
dimensions in Autocad .dwg
or .dxf file formats. We
will try to accommodate
other files as best we can.
2) Circuit Schematics and
Circuit Layer Drawing:
Based on your circuit design
schematics (electrical
design), we will generate
circuit layer drawing (the
actual physical circuit
layout artwork.)
3) Button Dome Actuation
Force:
To provide the tactile
feedback, normally a button
dome is used, although
special applications call
for non-tactile buttons.
Button domes can be
Stainless Steel Metal Dome
or Polyester Dome. No
appreciable difference
exists between these two
materials.
We can
provide dome sizes ranging
from 6mm, 8mm, 10mm, 12mm,
14mm, or 16mm.
4) Tail Connector:
Typical pitch for the tail
circuit and connector is
.100￣ (2.54mm) in the US.
1mm(0.0394￣) pitch is also
available.
5) Imbedded LEDs and
Resistors:
We can provide imbedded
surface mounted miniature
LEDs (typically 0805 type
SMD LEDs from Lite-On or
equivalent.) You must
specify the polarity (anode
and cathode) of each LED on
your mechanical drawings. We
can also provide imbedded
resistors.
6) Backlighting:
We can provide
electroluminescent
backlighting to your
membrane switch. Many
possibilities arise when you
backlight the keys or other
areas of membrane switch. EL
backlighting requires
inverter for the power
input.
7) Shielding:
We can provide EMI and RFI
shielding with Printed Metal
Grid Shielding or Aluminum
Shielding method. These
shielding are printed onto a
special layer or laminated
onto your circuit providing
protection against ESD or
EMI. The ground needs to be
connected with your switch
cable or by a dedicated
cable. When shielding is
inserted, we recommend to
increase the button
actuation force to be
increased by 2 oz since the
button tactile feedback is
reduced. Printed grid costs
slightly more but more
popular among our customers.
8) Rear Adhesive Tapes:
It is a very important part
of a membrane switch
performance. 3M 200MP
adhesives are formulated for
membrane switch
applications. 3M transfer
tapes 55230 or 467 with
200MP adhesives are popular
choices. Unless otherwise
specified by customers, we
use 3M 55230 or 467 adhesive
transfer tapes. |
