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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the testing of integrated circuit chips on
semi-conductor wafers and, more particularly, to apparatus for supporting
a probe card and an integrated circuit die during the testing of the
integrated circuits on the die.
2. Description of the Prior Art
Integrated circuits are formed as discrete chips on round semi-conductor
wafers. The integrated circuit chips are tested prior to the cutting of
the wafer. Typically, chips are tested by computer operated test apparatus
that exercises the circuits on the chips.
A probe card is an element which includes a plurality of electrical leads,
and the leads make contact with the various circuit elements on the
integrated circuit chip being tested. In the prior art, it is typical for
probe cards to be built by attaching metal needles to an epoxy ring. The
needles or probe elements may be secured to the ring by epoxy or they may
be bonded, as by welding, to a blade. The needles are individually placed
on the desired electrical elements of the chips for testing.
Integrated circuit dies are tested in a similar manner after they are
fabricated or processed. The dies are placed in a die carrier and a probe
card for testing the circuits on the die is placed adjacent to the die
with probe card needles contacting the various pads on the die for
testing.
The apparatus of the present invention uses a probe card similar to those
disclosed in the parent applications identified above.
U.S. Pat. No. 3,849,728 (Evans) discloses a probe card for testing
integrated circuit patterns. The apparatus includes a plurality of needles
secured to needle holders, and the needle holders are in turn secured to
conductive elements on a printed circuit board. The elements are all fixed
relative to each other.
U.S. Pat. No. 3,939,414 (Roch) discloses an integrated circuit testing
apparatus in which a test probe assembly includes elements for the precise
location of a test probe both axially and vertically.
U.S. Pat. No. 4,161,692 (Tarzwell) discloses another type of probe device
with probe needles secured to holder elements. The patent is primarily
directed to the holder elements for the probe needles.
U.S. Pat. No. 4,518,914 (Okubo et al) discloses test probe apparatus which
includes a probe card and needles extending outwardly and downwardly from
the probe card. The probe card is secured to a base plate by vacuum
pressure.
U.S. Pat. No. 4,636,722 (Ardezzone) discloses test probe apparatus which
includes a cutout portion and an element disposed in the cutout portion
adjacent to a probe assembly. The cutout portion of the Ardezzone patent
actually includes two "inserts" one of which is disposed on the top of the
apparatus and extends into the cutout portion, and the second is the one
referred to above, that is secured to the bottom of the cutout portion and
makes contact with the probe assembly.
U.S. Pat. No. 4,757,256 (Whann et al) discloses an epoxy ring probe card
apparatus in which a plurality of probe elements are secured to conductive
traces on the epoxy ring.
U.S. Pat. No. 4,758,785 (Rath) discloses integrated circuit testing
apparatus in which a probe card includes a plurality of probe elements and
a pressure pad disposed against the probe and secured to support structure
by resilient attaching elements to provide vertical movement of the
pressure pad relative to the probe for providing a desired pressure of the
probe against an integrated circuit to be tested.
U.S. Pat. No. 4,764,723 (Strid) discloses another type of probe apparatus.
The '723 apparatus is primarily directed to electrical connections
involved.
U.S. Pat. No. 4,791,363 (Logan) discloses another type of probe needle
apparatus. The probe needle apparatus includes a ceramic body, with a
microstrip circuit element on one side of the ceramic body and a ground
plane on the other side of the ceramic body. The probe apparatus of the
'363 patent is designed primarily for frequencies in the Gigahertz range.
U.S. Pat. No. 4,891,585 (Janko et al) discloses another type of probe
apparatus in which pressure contacts are made between the probe card
apparatus and circuit elements on a wafer being tested. U.S. Pat. No.
4,899,099 (Mendenhall et al) which includes what is referred to as a flex
dot wafer probe. The '099 apparatus appears to use thin film technology.
U.S. Pat. No. 4,906,920 (Huff et al) discloses a self-leveling membrane
probe apparatus. The apparatus includes another carrier element and
translation means disposed in a relatively movable relationship to the
carrier. Spring elements secure the carrier in the translation elements
together.
U.S. Pat. No. 4,912,399 (Greub et al) discloses another type of probe
apparatus. The probe apparatus uses contact elements on the bottom of a
support member, and the support member is used to provide a pressure
contact between the contact elements and the circuit elements under test.
U.S. Pat. No. 4,918,383 (Huff et al) discloses probe card apparatus with an
automatic contact scrub action. The automatic scrub action is accomplished
by using fixed length and variable length flexure assemblies. The
combination of fixed and variable length pivot assemblies results in a
lateral or sideways movement of probe contact elements which provides an
automatic scrubbing action of the contact element against the device under
test.
U.S. Pat. No. 4,981,817 (Stone) discloses method and structure for testing
integrated circuit chips using tape as a carrier for the integrated
circuit chips.
U.S. Pat. No. 5,006,792 (Malhi et al) discloses a socket adapter for
testing integrated circuit chips. A chip is inserted into the socket and
the socket is in turn appropriately connected to test apparatus.
U.S. Pat. No. 5,073,117 (Mahli et al) is a division of the above referenced
'792 patent and hence discloses substantially the same subject matter.
U.S. Pat. No. 5,088,190 (Mahli et al) discloses an integrated circuit test
apparatus which includes holder structure for the integrated circuit die
and connection elements for making electrical connection with the circuit
elements on the die. The integrated circuit chip is inserted into the top
of the holder apparatus and is biased downwardly to make the electrical
connection with the test circuitry elements.
The apparatus of the present invention utilizes individual needles on a
probe card, and the needles are bent downwardly at an angular orientation
from the horizontal to provide a scrubbing action on the integrated
circuit elements as the needles make contact with the integrated circuit.
The scrubbing action provides a cleaning for insuring that good electrical
contact is made between the needles of the probe card and the circuit
elements. The needles comprise continuation of conductive traces on a
probe card dielectric substrate.
The probe card of the present apparatus is secured to a probe card holder
that includes a movable or adjustable element which makes contact with the
probe card. A dielectric block insert in the probe card holder is
adjustable to provide a desired force on the probe card needles.
SUMMARY OF THE INVENTION
Invention described and claimed herein includes a probe card and a holder
for the probe card. The probe card includes a dielectric element on which
a plurality of needles and needle circuit elements are etched by
photolithography processes. The needles extend downwardly from the
dielectric material at a typical angular orientation of between 7 and 10
degrees from the horizontal, but which may vary from zero degrees to about
45 degrees, to provide a scrubbing action on the electrical circuit
elements of the integrated circuit when the probe card is moved downwardly
to contact the circuit elements. The needles are integral with, and
comprise continuations of, the needle circuit elements etched on the
dielectric element.
The probe card is secured to a base element or holder, and the holder
includes a dielectric block insert which makes contact with the needles.
The dielectric block includes a tapered edge portion which acts as a
fulcrum for the needles. The dielectric block insert is adjustable and is
spring loaded for varying the force against the probe card and against the
needles thereon.
Among the object of the present are the following:
To provide new and useful probe card apparatus;
To provide new and useful apparatus for testing integrated circuit chips;
To provide new and useful probe card apparatus having a plurality of probe
needles which contact circuit elements on an integrated circuit die;
To provide new and useful probe card apparatus having a plurality of
needles bent at an angle to the horizontal to provide a scrubbing action
as the needles contact electrical circuit elements on an integrated
circuit die;
To provide new and useful probe card apparatus in which probe needles
comprise continuations of circuit elements etched on a dielectric
substrate;
To provide new and useful apparatus for holding a probe card;
To provide new and useful apparatus for holding an integrated circuit die
and a probe card for testing the integrated circuit die;
To provide new and useful probe card holder apparatus having a movable
insert; and
To provide new and useful probe card apparatus including a probe card and a
holder for the probe card.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a perspective view of a portion of the apparatus of the present
invention.
FIG. 2 is a top plan view of a portion of the apparatus of the present
invention.
FIG. 3 is a view in partial section of the apparatus taken generally along
line 3--3 of FIG. 2.
FIG. 4 is an enlarged view in partial section taken generally from Circle 4
of FIG. 3.
FIG. 5 is a plan view of a portion of the apparatus of the present
invention.
FIG. 6 is an enlarged view of a portion of the apparatus of FIG. 5, taken
generally from Oval 6 of FIG. 5.
FIG. 7 is an enlarged view in partial section of a portion of an alternate
embodiment of the apparatus of the present invention.
FIG. 8 is an enlarged view in partial section of a portion of the apparatus
of the present invention in its use environment.
FIG. 9 is an enlarged view in partial section of a portion of another
embodiment of the apparatus of the present invention.
FIG. 10 is an end view of the die holder apparatus of the present
invention.
FIG. 11 is a perspective view of the apparatus of FIG. 10.
FIG. 12 is a top view, partially broken away, of the apparatus of FIGS. 10
and 11.
FIG. 13 is an exploded perspective view of the apparatus of FIGS. 10-12.
FIG. 14 is an exploded perspective view of an alternate embodiment of the
apparatus of FIGS. 10-13.
FIG. 15 is an enlarged view in partial section taken generally along line
15--15 of FIG. 14.
FIG. 16 is an exploded perspective view of another alternate embodiment of
the apparatus of FIGS. 10-13.
FIG. 17 is an enlarged view in partial section taken generally along line
17--17 of FIG. 16.
FIG. 18 is an enlarged view in partial section taken generally along line
18--18 of FIG. 17.
FIG. 19 is an enlarged view in partial section of a portion of the
apparatus of FIG. 16 as assembled.
FIG. 20 is an enlarged view in partial section of another alternate
embodiment of the apparatus of the present invention.
FIG. 21 is a side view in partial section of another alternate embodiment
of the apparatus of FIGS. 10-13.
FIG. 22 is a view in partial section illustrating the operation of another
alternate embodiment of the apparatus of FIGS. 10-13.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 is a bottom perspective view of a portion of the apparatus of the
present invention, comprising a membrane support assembly or probe card
apparatus 10. FIG. 2 is a top view of a portion of the membrane support
assembly 10. FIG. 3 is view in partial section of the membrane support
assembly 10 taken generally along line 3--3 of FIG. 2. The membrane
support assembly 10 includes a base element 12 and an insert 180. Both
elements are illustrated in FIGS. 1, 2, and 3.
FIG. 4 is an enlarged view in partial section of portions of the base
element 12 and the insert 180 taken generally from Circle 4 of FIG. 3. For
the following discussion of the membrane support assembly 10, reference
will primarily be made to FIGS. 1, 2, 3, and 4.
The base element 12 of the membrane support assembly 10 includes four
sides, including a side 14, a side 16, a side 18, and a side 20. The four
sides define a generally square base element. The base element 12 also
includes a planar top 22. The sides 14 . . . 20 are generally
perpendicular to the planar top 22, The sides are conveniently rounded at
the juncture of adjacent sides, which comprise the corners of the base
element 12.
Extending downwardly through the base element 12 from the top 22 is a
series of stepped cutouts. The top cutout is a cutout 24. The cutout 24 is
illustrated as square, but its configuration, and the configuration of all
of the cutouts, will conform to the configuration of the chips being
tested. Thus, the cutout 24 will be square for testing a square chip,
rectangular for testing a rectangular chip, etc.
The cutout 24 extends downwardly to a generally horizontally extending and
inwardly directed shoulder 26. Extending downwardly from the inner portion
of the shoulder 26 is an intermediate cutout 28. The cutout 28 extends
vertically downwardly to a shoulder 30. The shoulder 30 extends inwardly
from the cutout 28 to a lower cutout 32. At the bottom portion of the
cutout 32 is an inwardly directed shoulder 34.
From the interior of the shoulder 34 there is an inner or bottom cutout 36.
The cutout 36 extends downwardly to a bottom inner flat surface 60 which
extends outwardly from the cutout 36. Extending inwardly from the four
sides 14, 16, 18, and 20 is a bottom outer flat surface 38. Extending
upwardly into the bottom outer flat surface 38 are four slots. The four
slots are adjacent and generally parallel to the respective four sides.
The slots include a slot 40 which is generally parallel to the side 14, a
slot 42 which is generally parallel to side 16, a slot 44 which is
generally parallel to the side 18, and a slot 46 which is generally
parallel to the side 20. The slots receive resilient pressure contacts
elements. A resilient element 43 is shown in FIG. 3 in slot 42.
Extending inwardly and downwardly from the bottom outer flat surface 38 are
four tapered surfaces. Each of the tapered surfaces is in the general
configuration of a trapezoid, with the non-parallel sides having equal
lengths. The tapered surfaces include a tapered surface 50, a tapered
surface 52, a tapered surface 54, and a tapered surface 56. The tapered
surfaces extend inwardly from the outer flat surface 38 to the inner flat
surface 60. The inner flat surface 60 is disposed between the tapered
surfaces and the bottom cut out 36.
The inner or bottom flat surface 60 is generally parallel to the top planar
surface 22, and to the outer planar surface 38.
There are four apertures at the four corners of the base element 12
adjacent to the outer sides. The four apertures include an aperture 70
adjacent to the juncture of the sides 14 and 16, an aperture 72 adjacent
to the juncture of the sides 16 and 18, an aperture 74 adjacent to the
juncture or corner of the sides 18 and 20, and an aperture 76 adjacent to
the juncture or corner of the sides 20 and 14.
The apertures 70, 72, 74, and 76 receive fastening elements, such as
screws, to secure the base element 12 and a probe card or membrane card to
a printed circuit board in the use environment. In FIG. 3, a portion of a
printed circuit board 2 is shown secured to the base element 12 and a
probe card 300 by a screw assembly 4. The screw assembly 4 includes a ring
or washer or the like, a screw which extends through the aperture 72, and
a nut.
Extending downwardly from the shoulder 26 are four tapped apertures. Two of
the tapped apertures are shown in FIG. 3. The two tapped apertures shown
in FIG. 3 include an aperture 82 and an aperture 86. The tapered apertures
will be discussed in more detail below.
Extending downwardly from the bottom outer flat surface 38 are four pairs
of pins. The four pairs of pins include a pair of pins 90, a pair of pins
92, a pair of pins 94, and a pair of pins 96. The pairs of pins 90 . . .
96 are used to help index the membrane or probe card 300 to the base 12
and to help index or align the card 300 to the printed circuit board 2 in
order to insure correct electrical contact and alignment between
electrical contact elements on both the circuit board 2 and the card 300.
Obviously, the board 2 will have apertures (not shown) to receive the pin
pairs from the element 10. This will be discussed in more detail below.
A top plate 100 is disposed in the cutout 24 and rests on the shoulder 26.
The top plate 100 has a configuration to appropriately match that of the
cutout 24. The overall height or thickness of the plate 100 is about the
same as the overall depth of the cutout 24. This is best illustrated in
FIG. 3.
The top plate 100 includes a top surface 102 and a bottom surface 104. The
bottom surface 104 is disposed on the shoulder 26. The top plate 100
includes four sides 110, 112, 114, and 116. The four sides are spaced
inwardly a relatively slight amount from the sides of the cutout 24 in
which the plate 100 is disposed.
As best shown in FIG. 2, the four corners of the plate 100, or the
junctures of adjacent sides, are gently rounded, as are the corners of the
cutout 24. Spaced inwardly from the rounded corners of the plate 100 are
four apertures. The apertures receive cap screws which secure the plate
100 within the cutout 24 to the base element 12. An aperture 130 is shown
in FIG. 3 aligned with the tapped aperture 82 in the base element 12. A
cap screw 162 is shown extending through the aperture 130 and into the
tapped aperture 82. A second aperture 150 is shown in FIG. 3 aligned with
the tapped aperture 86 in the base element 12. A cap screw 168 is shown
extending through the aperture 150 and into the tapped aperture 86. In
addition to the cap screws 162 and 168, shown in both FIGS. 2 and 3, two
other cap screws, a cap screw 164 and a cap screw 166, are shown in FIG.
2, extending through apertures 136 and 142, respectively.
There are other apertures extending through the plate 100 for other
purposes. There are generally three apertures aligned from each of the
corners inwardly, as best shown in FIG. 2. The apertures include an
aperture 132 and an aperture 134 which extend inwardly and are aligned
with the aperture 130 from the corner which comprises the juncture of the
sides 110 and 112.
A pair of apertures 138 and 140 extend inwardly from the aperture 136 in
which the cap screw 164 is illustrated, and which three apertures are
aligned inwardly from the corner which defines a juncture of the sides 112
and 114.
Three apertures extend inwardly from the corner which defines the juncture
of sides 114 and 116. They include an aperture 142 through which the cap
screw 166 extends, and they also include an aperture 144 and an aperture
146. Similarly, three apertures extend inwardly from the corner which
defines the juncture of the sides 116 and 110. They include the aperture
150 (see FIG. 3) and an aperture 152 and an aperture 154.
The apertures 132, 138, 144, and 152 are tapped. The four tapped apertures
receive set screws which include spring loaded balls on the bottom of the
set screws. Two of the set screws are shown in FIG. 3. The tops of the
four set screws are also shown in FIG. 2. They include a set screw 172 in
the aperture 132, a set screw 174 in the aperture 138, a set screw 176 in
the aperture 144, and a set screw 178 in the aperture 152.
The set screws 172 . . . 178 are adjustable in their respective tapped
apertures, as will be discussed in detail below.
The inner apertures 134, 140, 146, 154 provide communication through the
plate 100 to elements on the insert 180, as will be discussed in detail
below.
Disposed beneath the plate 100 and within the cutout 128 in the base
element 12 is the dielectric insert 180. The dielectric insert 180 is
generally of a square configuration, but having a stepped outer
configuration. The stepped configuration includes both internal and
external, or inside and outside, steps. The overall configuration of the
insert 180 will, of course, conform to that of the cutouts 28 and 36,
which in turn conform to the configuration of the cutout 24. Details of
the dielectric insert or block 180 are shown in both FIGS. 3 and 4.
The dielectric insert 180 includes a top surface 182 and four upper sides
defined by an outer periphery 184. Extending inwardly from the lower
portion of the outer periphery 184 is an upper bottom shoulder 186. The
bottom shoulder 186 is disposed above the bottom or shoulder 30 on the
base element 12.
Extending downwardly from the bottom shoulder or surface 186 is another
downwardly extending portion defined by an outer periphery 188. Extending
inwardly from the bottom of the downwardly extending peripheral surface
188 is an inwardly extending shoulder 190. The inwardly extending shoulder
190 is a bottom shoulder. It is disposed above shoulder 34 of the base
element 12.
Extending downwardly from the inner termination of the shoulder 190 is a
downwardly extending portion 192.
From the bottom of the downwardly extending portion 192 is a tapering or
tapered portion 194. The tapered portion 194 terminates in a bottom
fulcrum 196.
The interior of the dielectric insert 180 includes an upper cut out 200.
The cutout 200 is generally parallel to the outer peripheral surface 184
of the insert 180. Extending inwardly from the bottom of the cutout 200 is
an inner peripheral shoulder 202. Extending downwardly from the inner
peripheral shoulder 202 is a lower cut out 204.
As may be seen from FIGS. 1, 2, and 3, the upper cutout 200 and the lower
cut out 204 provide visual communication through the center of the
apparatus 10 to allow visual alignment of the apparatus 10 with the
integrated circuit elements that are to be tested on a wafer or chip
disposed beneath of apparatus 10.
There are four inner tapped apertures which extend through the upper
portion of the insert 180. The apertures are disposed inwardly from the
four corners, or adjacent to the four corners of the outer periphery 184.
The tapped apertures extend between the top surface 182 and the upper
bottom shoulder 186. Set screws are disposed in the tapped apertures. Two
of the set screws are shown in FIG. 3. The two set screws shown in FIG. 3
include a set screw 210 and a set screw 216.
The four inner set screws, including the set screws 210 and 216, are
adjusted through the inner apertures 134, 140, 146 and 154 in the top
plate 100. The adjustment of the four inner set screws, including the set
screws 210 and 216, determines the initial location of the fulcrum 196
(see FIG. 4) beneath the bottom surface 60 of the base element 12.
The location or vertical placement of the set screws 172 . . . 178
determines the upper limit, or the allowable movement, of the insert 180.
Since the set screws 172 . . . 178 include spring loaded balls on or at
their bottoms, and the spring loaded balls bear against the top surface
182 of the insert 180, it is obvious that upward pressure or force on the
dielectric insert 180 may move the insert 180 upwardly until the spring
loaded balls bottom out against the fixed portions of their respective set
screws.
By use of the spring loaded set screws 172 . . . 178 which are secured in
the top plate 100 and the use of the inner set screws in the insert 180,
it is obvious that the insert 180 may be adjusted in any manner desired.
It may be canted at any certain orientation, it may be level with respect
to the appropriate surfaces of the base element 12, or it may be tilted in
any particular direction, etc. Moreover, the adjustment of the set screws
172 . . . 178 with the spring loaded balls allows movement of the insert
180 up to a predetermined amount without damage to any of the elements
involved. This will be discussed in detail below in conjunction with the
membrane card or probe card 300 best illustrated in FIGS. 5 and 6 and as
shown in its use environment in FIG. 4.
Referring again to FIG. 3, it will be noted that the apparatus 10, with the
insert 180 and the card 300, may also be adjusted relative to the board 2
by varying the force or pressure against the resilient inserts in the
slots 40 . . . 46, such as against the insert 43 in the slot 42 and
against the insert, not shown, in the slot 44 by means of the screw
assembly 4. The force or pressure against the other inserts in the other
slots adjacent to the corners is adjusted by similar screw assemblies. The
initial planarity of the base element 10 and the card 300, with respect to
the board 2, is adjusted by the screw assemblies at the four corner
apertures 70 . . . 76 of the base 12 and the mating and aligned apertures
in the card 300 and the board 2. As indicated above, the insert 180 may
also be separately or independently adjusted relative to the base element
12 by the various set screws discussed.
FIG. 5 is a top view of a portion of the membrane test card or probe card
300 usable with the base element 12 and the insert 180 as discussed above.
FIG. 6 is an enlarged view of a portion of the card 300 taken generally
from Oval 6 of FIG. 5. For the following discussion, reference will
primarily be made to FIGS. 5 and 6. Additional reference will also be made
to FIG. 4 and to other figures as required.
The membrane or probe card 300 includes a flexible dielectric substrate or
membrane 302 containing a plurality of metallic conductive traces 308. The
traces 308 may be fabricated either through photolithography processes,
well known and understood in the art, or they may be plated up to a
desired thickness by plating or deposition techniques also well known and
understood in the art.
The membrane card 300 is generally square in configuration, conforming to
the general configuration of the base 12. For aligning the card 300 to the
base 12, there are a number of apertures. An aperture 304 is shown
adjacent to a corner of the card. The aperture 304 will be aligned with
one of the four corner apertures 70 . . . 76 of the base 12. Spaced
inwardly from the aperture 304 is a pair of index apertures 306. The index
apertures 306 receive a pair of indexing pins, such as one of the pin
pairs 90 . . . 96, shown in FIG. 1.
The metallic traces 308 terminate inwardly in a plurality of needles 310.
It is the needles 310 that actually make contact with the electrical
elements on the integrated circuits on a wafer for test purposes. The
needles 310 extend inwardly from a center aperture or cutout 314 of the
substrate 302. The needles 310 are simply continuations of the traces 308,
and are accordingly integral with the traces. No separate needle elements
are required.
Outwardly the traces 308 make electrical contact with corresponding traces
3 on the printed circuit board 2 when the apparatus 10 is secured to the
circuit board 2, as discussed above. This is illustrated in FIG. 3.
The center aperture or cutout 314 is a squarely configured cutout which is
generally aligned with the inner or bottom cutout 36 of the base element
12 and the bottom cutout 204 of the insert 180. The center cutout 314
allows for the visual alignment of the needles 310 with the integrated
circuit elements being tested.
The needles or contact elements 310, extending inwardly from the cutout
314, are bent downwardly at an acute angle from the plane of the substrate
302 of typically about 10 degrees, but the angle may vary, as indicated
above. As best shown in FIG. 4, the fulcrum 196 of the dielectric block
insert 180 makes contact with the needles. The fulcrum 196 of the insert
180 provides a positive downward bias for the needles 310.
The card 300 is preferably adhesively secured to the base 12. Of particular
concern is the securing of the portion of the card disposed out or against | | |
