Figure 1 shows the design of an electrical connector that
is used to transmit electrical signals in computers. When
the male pins are inserted into female cavities, metal
strips placed in the female cavities deflect, exerting loads
to the pin to make electric contacts. The FRs of this signal
connector are to transmit signal, have a low contact
resistance, require a low insertion force, have a high
power density, and have a high pin density. Is this
connector "complex"? Why? Can we reduce the
complexity of the electrical connector system? This is a
complex design because it becomes a coupled design
when the design ranges for the FRs are reduced. For
example, one of the FRs is to have a high power density
without raising the temperature of the connector above a
certain critical temperature. Another FR is to provide a
good electric contact with less than 20 m_ between the
male pin and the female strips. Yet another FR is to
minimize the insertion force. In less demanding
applications, these FRs are easily satisfied within their
design ranges. i.e. they do not seem to be complex.
However, as we make these connectors smaller and
smaller, as we increase the power density, and as the
number of pins increases, it becomes more difficult to
satisfy the FRs related to power density, low insertion
force, and low contact resistance. For instance, to obtain
good electrical contacts, the normal load between the pin
and the strip must be high, but it increases the insertion
force. Also to have a sufficiently high interfacial force
between the pin and the strip, the strips must be stiff.
Therefore, it must be made of a copper alloy (often
beryllium copper) rather than pure copper. However,
beryllium copper increases the electrical resistance,
raising i2R energy dissipation, which limits the maximum
power density of the connector due to the temperature
rise. Because of these coupling of FRs, it is difficult to
satisfy the FRs. The FRs of these conventional
connectors must be fine-tuned (or optimized),
compromising and sacrificing some of the FRs. This type
of classical coupled design is very complex since there is
a great deal of uncertainty in satisfying the FRs.