by an ultrasonic cutter into small, rectangular chips. These chips of indium
arsenide are then placed on a thin ceramic substrate and soldered to a
conducting pattern on the substrate, as shown in Figure 7.28.
Once made, the Hall probe is normally coated with epoxy to protect the
semiconductor compound and other components.
To use the probe, an electric current is passed through the length of the
In As chip, as shown in Figure 7.29. Note that the contact areas for passing
current through the Hall element are made larger than the ones for detecting
the Hall voltage. Typically, current on the order of 10−1 A is passed through
the Hall element. This is known as the control current. Care must be taken
when using a Hall probe never to put the control current through the output.
Because the solder contacts for the voltage sensing are very small, the
control current can melt these solder joints. This may destroy or damage the
Hall probe.