Improved probing of closely spaced contact pads is provided by an array of vertical probes having all of the probe tips aligned along a single contact line, while the probe bases are arranged in an array having two or more rows parallel to the contact line. With this arrangement of probes, the probe base thickness can be made greater than the contact pad spacing along the contact line, thereby advantageously increasing the lateral stiffness of the probes. The probe tip thickness is less than the contact pad spacing, so probes suitable for practicing the invention have a wide base section and a narrow tip section.