| US 7,518,384 B2 | ||
| Method and apparatus for manufacturing and probing test probe access structures on vias | ||
| Glen E Leinbach, Fort Collins, Colo. (US); and Kenneth P Parker, Ft Collins, Colo. (US) | ||
| Assigned to Agilent Technologies, Inc., Santa Clara, Calif. (US) | ||
| Filed on Jan. 31, 2005, as Appl. No. 11/47,070. | ||
| Prior Publication US 2007/0018663 A1, Jan. 25, 2007 | ||
| Int. Cl. G01R 31/02 (2006.01) | ||
| U.S. Cl. 324—754 [324/756] | 9 Claims |

| 1. A method for probing an access point on a printed circuit assembly,
wherein the access point includes (i) a via having an electrically conductive perimeter in the shape of an annulus, and (ii)
a test probe access structure which includes first and second bead probes formed on first and second positions on the electrically
conductive perimeter, the bead probes being formed of electrically conductive solder, and being formed such that either (a)
both of the first and second bead probes project in a dimension substantially perpendicular to the printed circuit assembly,
or (b) one of the first and second bead probes project in a dimension substantially perpendicular to the printed circuit assembly
and the other of the first and second bead probes is incorrectly formed so as to make the other of the first and second bead
probes ineffective to project in a direction substantially perpendicular to the printed circuit assembly;
the method comprising:
aligning a fixture probe with the access point;
engaging the fixture probe with the access point, wherein either (a) the engaging causes the fixture probe to make physical
contact with both of the projecting first and second bead probes, or (b) the engaging causes the fixture probe to make physical
contact with the one of the first and second bead probes which projects in a direction substantially perpendicular to the
printed circuit assembly, but not with the other of the first and second bead probes; and
exerting compressive contact between the fixture probe and the access point, so as to deform (a) both of the first and second
bead probes which project in a direction substantially perpendicular to the printed circuit assembly, or (ii) the engaged
one of the first and second bead probes, in the case where the other one of the first and second bead probes is incorrectly
formed;
whereby the deforming facilitates electrical contact between the fixture probe and the test probe access structure.
|