Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
1997-04-21
2002-04-02
Nguyen, Vinh P. (Department: 2858)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
C324S765010
Reexamination Certificate
active
06366105
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to methods and apparatus for testing electrical circuits formed upon substrates such as but not limited to printed circuit substrates, ceramic substrates and semiconductor integrated circuit substrates. More particularly, the present invention relates to methods and apparatus for reliably testing electrical circuits formed upon substrates such as but not limited to printed circuit substrates, ceramic substrates and semiconductor integrated circuit substrates.
2. Description of the Related Art
Known in the arts of fabricating electrical circuits upon substrates such as but not limited to printed circuit substrates, ceramic substrates and semiconductor integrated circuit substrates is the use of electrical test apparatus, often in conjunction with the use of accelerated physical stress apparatus, to determine and/or assure the functionality and/or reliability of electrical circuits formed upon the substrates such as but not limited to the printed circuit substrates, the ceramic substrates and the semiconductor integrated circuit substrates. The use of electrical test apparatus, with or without the use of accelerated physical stress apparatus, may be employed at several process stages within electrical circuit fabrication, including but not limited to: (1) early electrical circuit fabrication process stages where the electrical test apparatus may be employed as an in-process test apparatus; and (2) later electrical circuit fabrication process stages where the electrical test apparatus may be employed as a final test apparatus and/or a product certification apparatus.
Electrical test apparatus employed in testing electrical circuits formed upon substrates such as but not limited to printed circuit substrates, ceramic substrates and semiconductor integrated circuit substrates typically provide direct physical contact to conductor contacts such as but not limited to bond pads which access upon the substrates electrical circuits whose electrical characteristics it is desired to test. The electrical test apparatus typically make physical contact with the conductor contacts through use of needle like tapered conductive probe tips which bridge from a probe card which forms a part of a tester head assembly within an electrical test apparatus to the conductor contacts which access the electrical circuits whose electrical characteristics it is desired to test. Conductive probe tips are typically configured within a probe card within a tester head assembly within an electrical test apparatus in a fashion such that they dissipate and distribute a loading pressure employed when contacting the conductive probe tips to the conductor contacts formed upon a substrate.
Shown in FIG.
1
and
FIG. 2
is a pair of schematic cross-sectional diagrams illustrating operation of an electrical test apparatus conventional in the art of testing electrical circuits formed upon substrates such as but not limited to printed circuit substrates, ceramic substrates and semiconductor integrated circuit substrates. Shown in
FIG. 1
is a platen
10
upon which is fixed a substrate
16
which may be chosen from the group of substrates including but not limited to printed circuit substrates, ceramic substrates and semiconductor integrated circuit substrates. Positioned in a first position adjoining but not in contact with the substrate
16
is a tester head assembly
12
which comprises a mounting block
122
having fixed thereupon a probe card
124
which in turn has disposed thereupon a minimum of one conductive probe tip
126
through which contact to a conductor contact (not shown) upon the substrate
16
is ultimately made. Also shown in
FIG. 1
is an aperture
128
through the tester head assembly
12
, which aperture
128
allows for access of a microscope
14
employed in assuring proper registration of the probe tips
126
with corresponding conductor contacts (not shown) formed upon the substrate
16
. Shown in
FIG. 2
is a schematic cross-sectional diagram illustrating the results of further processing of the substrate
16
within the electrical test apparatus as illustrated in FIG.
1
. Shown in
FIG. 2
is the results of repositioning the tester head assembly
12
from the first position with respect to the platen
10
as shown in
FIG. 1
to a second position with respect to the platen
10
such that the conductive probe tips
126
contact the conductor contacts (not shown) within the substrate
16
, thus allowing electrical measurements to be obtained of electrical circuits accessed through the conductor contacts (not shown) formed upon the substrate
10
.
While the use within electrical test apparatus of conductive probe tips as contact elements bridging probe cards with conductor contacts formed upon substrates such as but not limited to printed circuit substrates, ceramic substrates and semiconductor integrated circuit substrates has become quite common in the art of testing electrical circuits formed upon substrates such as but not limited to printed circuit substrates, ceramic substrates and semiconductor integrated circuit substrates, the use within electrical test apparatus of conductive probe tips as contact elements bridging probe cards with conductor contacts formed upon substrates is not entirely without problems. In particular, it is known in the art that use of electrical test apparatus employing conductive probe tips as contact elements bridging probe cards with conductor contacts formed upon substrates suffers from several problems which relate to contact resistance increases between the conductive probe tips and the conductor contacts, including but not limited to: (1) conductive probe tip contact resistance increases due to conductive probe tip contact with adventitious non-conductive particulate deposited upon conductor contacts; (2) conductive probe tip contact resistance increases due to oxidation of conductor contact material which has transferred to a conductive probe tip; and (3) conductive probe tip contact resistance increases due to oxidation of conductive probe tip material when testing electrical circuits at elevated electrical test apparatus temperature. Such conductive probe tip contact resistance increases are undesirable since they may provide erroneous indications of non-functional or unreliable electrical circuits formed within substrates, thus erroneously reducing fabrication yields those substrates. It is thus towards providing: (1) an electrical test apparatus employing a conductive probe tip bridging to a conductor contact accessing an electrical circuit upon a substrate such as but not limited to a printed circuit substrate, a ceramic substrate or a semiconductor integrated circuit substrate; and (2) a method for employing the electrical test apparatus which employs the conductive probe tip bridging to the conductor contact accessing the electrical circuit upon the substrate, while avoiding the foregoing conductive probe tip contact resistance increases, that the present invention is directed.
The use of electrically conducting probes as a means for providing measurements within various technology applications, including but not limited to electrical circuit fabrication applications, is generally known within the various pertinent technology arts. For example, Gray et al., in U.S. Pat. No. 5,415,042 discloses a measuring probe for detecting the presence of an electrically conducting liquid or granular material contained within a vessel, The measuring probe employs a gas purge to clear the electrically conducting liquid or granular material from between the conducting electrodes of the measuring probe. In addition, Barnett et al., in U.S. Pat. No. 4,872,356 discloses a resistivity probe apparatus which provides an enclosure for a resistivity probe employed in monitoring resistivity of deionized water employed in rinsing semiconductor substrates employed within integrated circuit fabrication. The resistivity probe apparatus provides several advantages directed towards pr
Ackerman Stephen B.
Nguyen Vinh P.
Saile George O.
Szecsy Alek P.
Taiwan Semiconductor Manufacturing Company
LandOfFree
Electrical test apparatus with gas purge does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electrical test apparatus with gas purge, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electrical test apparatus with gas purge will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2819697