American Dynamics PMC-4U-CACI - Manual (Page 29)

Hardware and Software Design • Manufacturing Services
P a g e 29
Construction and Reliability
PMC Modules were conceived and engineered for rugged industrial
environments. The PMC-4U is constructed out of 0.062 inch thick FR4
material.
Through hole and surface mounting of components are used. IC sockets
use gold plated screw machine pins. High insertion and removal forces are
required, which assists in the retention of components. If the application
requires unusually high reliability or is in an environment subject to high
vibration, the user may solder the corner pins of each socketed IC into the
socket, using a grounded soldering iron.
The PMC connectors are rated at 1 Amp per pin, 100 insertion cycles
minimum. These connectors make consistent, correct insertion easy and
reliable.
The PMC secured against the carrier with four screws attached to the 2
stand-offs and 2 locations on the front panel. The four screws provide
significant protection against shock, vibration, and incomplete insertion.
The PMC Module provides a low temperature coefficient of 2.17 W/oC for
uniform heat. This is based upon the temperature coefficient of the base
FR4 material of 0.31 W/m-oC, and taking into account the thickness and
area of the PMC. The coefficient means that if 2.17 Watts are applied
uniformly on the component side, then the temperature difference between
the component side and solder side is one degree Celsius.
Thermal Considerations
The PMC-4U design consists of CMOS circuits. The power dissipation due
to internal circuitry is very low. It is possible to create a higher power
dissipation with the externally connected logic. If more than one Watt is
required to be dissipated due to external loading then forced air cooling is
recommended. With the one degree differential temperature to the solder
side of the board external cooling is easily accomplished.