(1) requires that the distance from the edge of the probe to the edge of the material is much larger than the probe spacing, and generally requires more than 10 times.
(2) The probe spacing should be equal, otherwise it will lead to proportional test error.
(3) Theoretically, the smaller the contact point between the probe and the conductive film, the better. However, in practical application, because the needle electrode is easy to destroy the conductive thin film material to be tested, a circular probe is generally used.