Transposed via arrangement in probe card for automated test equipment
A probe card in an automated test equipment (ATE) is disclosed. The probe card may be a portion of a vertical-type probe card assembly in which pads on a circuit board are contacted by probe pins, with vertical vias in the circuit board interconnecting various conductive elements. Disclosed herein is a transposed via arrangement within a circuit board for a probe card, where adjacent vias are offset towards each other such that the inductance between the adjacent vias may be reduced to provide a desirable impedance during high frequency signal and/or power transmission.
1. A probe card for testing a semiconductor wafer, the probe card comprising:
a board having a first pad and a second pad disposed adjacent each other along a first direction parallel to a first surface of the board configured to face the semiconductor wafer;
a first via and a second via in the board, the first via having a first contact surface in direct contact with the first pad, the second via having a second contact surface in direct contact with the second pad, wherein:
a center of the first contact surface and a center of the second contact surface are offset towards each other along the first direction from respective centers of the first and second pads,
wherein the first via is in direct contact with a first plane, the second via is in direct contact with a second plane, wherein the first plane is a power plane, and the second plane is a ground plane, and
wherein the first plane overlaps the second plane in a direction perpendicular to the first surface.
2. The probe card of claim 1 , wherein:
the second plane is parallel to and offset from the first plane.
3. The probe card of claim 1 , wherein the board comprises a plurality of dielectric layers, and wherein the first via is a stack of a plurality of conductive fill material disposed within respective dielectric layers.
4. The probe card of claim 3 , wherein the board is a multiple layer organic (MLO) board.
5. The probe card of claim 1 , wherein the probe card is part of a probe card assembly that comprises a plurality of probe pins in contact with the first pad and the second pad, and configured to connect the first pad and second pad to respective pads on the semiconductor wafer.
6. The probe card of claim 1 , wherein the first plane comprises a pad disposed on a second surface of the board that is opposite the first surface.
7. The probe card of claim 1 , wherein the first contact surface of the first via has a rectangular shape with a long edge parallel to a second direction perpendicular to the first direction.
8. The probe card of claim 7 , wherein the first via has a trapezoidal shape at a cross-section along a plane perpendicular to the second direction.
9. The probe card of claim 1 , wherein the first contact surface of the first via has a circular shape, and wherein the probe card further comprises an array of vias in direct contact with the first pad at respective contact surfaces, wherein the array of vias comprises a column of vias having contact surfaces aligned with the first contact surface of the first via along a second direction perpendicular to the first direction.