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FEBRUARY 2019    TAP TIMES          -4-


                  Kelvin sockets (from 3)








                                                                                           Force(F)
                                                                                           Sense(S)
                                                                                                   Sensing     Forcing
                                                                                                   Meter       Current
                                                                                           Sense(S)

                                                                                           Force(F)
                                                                                        FIGURE 1
                                                                   Schematic depicts how a kelvin socket works.
                                                                                      Kelvin Socket
                                                                                           (Loranger International)

                                                                device under test.  In addition, adds Del-
                                                                gado, “when fabricated correctly and the
        Lord Kelvin is probably best known for the scientific com-
        munity’s adoption of his name for a unit of measurement.  appropriate material is used, kelvin sock-
                                                                ets can provide years of service in a very
        In a typical application, says Warner, a                demanding environment.”
        relatively high current passes through the                                                    —Ron Iscoff
        force contacts.



        Greater accuracy
        Measurements using kelvin sockets, says
        Warner, “are much more accurate” than
        traditional sockets because the contact
        and interface resistance of the high cur-
        rent force contacts does not affect the
        accuracy of the voltage reading across the
        sense contact.

        Why employ kelvin sockets?  There are
        four basic reasons, says Loranger’s War-
        ner: First, they allow accurate measure-
        ment of very low resistance values; they
        also offer accurate voltage measurement.


        In addition, they provide assurance of test
        and improved heat dissipation.

        Both test and burn-in kelvin sockets are
        offered in a wide variety of configurations.
        Among the kelvin socket’s benefits, says
        Bobby Delgado, Precision Contacts engi-
        neer,  is that a kelvin socket can be tasked
        with accurately guiding and orienting the
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