User Guide

Hardware and Software Design • Manufacturing Services
P a g e 35
Construction and Reliability
PMC Modules were conceived and engineered for rugged industrial environments.
The PMC BiSerial-II is constructed out of 0.062 inch thick FR4 material.
Through hole and surface mounting of components are used. IC sockets use
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 is 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/
o
C for
uniform heat. This is based upon the temperature coefficient of the base FR4
material of 0.31 W/m-
o
C, 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 BiSerial II 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.