Probe head structures for circuit probe test systems and methods of forming the same

A probe head for a circuit probe test system, comprising:

• a guide plate comprising a plurality of openings through the guide plate;
• a low-k material layer having a dielectric constant that is less than a dielectric constant of the guide plate over a surface of the guide plate and extending between a pair of the openings;
• a conductive trace over the low-k material layer;
• a plurality of probe pins extending through the openings through the guide plate, wherein a pair of probe pins are electrically connected by the conductive trace to form a loopback signal path;
• and
• an adhesion layer comprising an electrically conductive material over the surface of the guide plate between the low-k material layer and the surface of the guide plate, wherein the adhesion layer electrically couples at least two of the plurality of probe pins extending through the openings in the guide plate.

A probe card for a circuit probe test system, comprising:

• a substrate portion;
• an upper guide plate and a lower guide plate located below the substrate portion, each of the upper guide plate and the lower guide plate comprising a plurality of openings;
• a plurality of probe pins extending through the plurality of openings in the lower guide plate, the plurality of probe pins comprising at least one first probe pin configured to carry power between the substrate portion and a device-under-test (DUT), at least one second probe pin configured to electrically couple the DUT to ground, and at least two third probe pins configured to carry loopback test signals between contact regions on the DUT, wherein the at least two third probe pins extend through the plurality of openings in the lower guide plate but not through the plurality of openings in the upper guide plate;
• a conductive trace on a lower surface of the upper guide plate electrically coupling the at least two third probe pins to provide a loopback signal path;
• and
• a low-k material layer having a dielectric constant less than a dielectric constant of the lower guide plate, the low-k material layer located within the openings in the lower guide plate through which the at least two third probe pins extend.