U.S. patent application number 10/053506 was filed with the patent office on 2002-06-27 for tightening rings for integrated circuit tester heads.
This patent application is currently assigned to SGS-Thomson Microelectronics S.A.. Invention is credited to Bailly, Jean-Michel, Girolet, Bernard, Milesi, Roger, Noraz, Denis.
Application Number | 20020079884 10/053506 |
Document ID | / |
Family ID | 9506442 |
Filed Date | 2002-06-27 |
United States Patent
Application |
20020079884 |
Kind Code |
A1 |
Milesi, Roger ; et
al. |
June 27, 2002 |
Tightening rings for integrated circuit tester heads
Abstract
The present invention relates to an assembly ring, on a test
head, of a wafer that provides an interface of electric contact
transfer between the test head and a circuit to be tested,
including a disk, open in its central portion and meant for
supporting the periphery of the wafer; a removable collar assembly
of the ring on the test head; and means for rotatably connecting
the disk in the vicinity of a free end of the collar.
Inventors: |
Milesi, Roger; (Saint Martin
D'Uriage, FR) ; Noraz, Denis; (Saint Nazaire Les
Eymes, FR) ; Girolet, Bernard; (Grenoble, FR)
; Bailly, Jean-Michel; (Allevard, FR) |
Correspondence
Address: |
James H. Morris
Wolf, Greenfield & Sacks, P.C.
Federal Reserve Plaza
600 Atlantic Avenue
Boston
MA
02210
US
|
Assignee: |
SGS-Thomson Microelectronics
S.A.
7, Avenue Gallieni
Gentilly
FR
94250
|
Family ID: |
9506442 |
Appl. No.: |
10/053506 |
Filed: |
October 26, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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|
10053506 |
Oct 26, 2001 |
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09845525 |
Apr 30, 2001 |
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09845525 |
Apr 30, 2001 |
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09634367 |
Aug 9, 2000 |
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09634367 |
Aug 9, 2000 |
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09066211 |
Apr 24, 1998 |
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6127818 |
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Current U.S.
Class: |
324/762.03 |
Current CPC
Class: |
G01R 1/04 20130101 |
Class at
Publication: |
324/158.1 |
International
Class: |
G01R 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 24, 1997 |
FR |
97/05317 |
Claims
What is claimed is:
1. An assembly ring, on a test head, of a wafer that provides an
interface of electric contact transfer between the test head and a
circuit to be tested, including: a disk, having an open central
portion and meant for supporting a periphery of the wafer; a collar
of removable assembly of the ring on the test head; means for
fixing the disk in translation motion to a free end of the collar;
and means for making the disk freely rotatable with respect to the
collar.
2. The assembly ring of claim 1, wherein the rotatable connection
means are formed of a ball bearing.
3. The assembly ring of claim 1, wherein die disk includes
insulating pads for receiving the periphery of the wafer.
4. The assembly ring of claim 3, wherein the pads are formed by
concentric rings attached to the upper surface of the disk.
5. The assembly ring of claim 1, wherein the wafer is a printed
circuit wafer.
6. The assembly ring of claim 1, meant for a head for testing
integrated circuit chips.
7. The assembly ring of claim 1, wherein the assembly ring is meant
for an integrated circuit test head.
8. An integrated circuit testing device, of the type including a
test head for receiving, removably, a printed circuit wafer that
provides an interface of contact transfer between the test head and
an integrated circuit to be tested, including a removable ring
assembly on the test head of claim 1.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to the field of integrated
circuit testing devices. The present invention more specifically
relates to an assembly ring for a contact transfer interface
between a test head of a testing device and a conductive tip board
itself transferring the contacts from the interface to an
integrated circuit chip to be tested.
[0003] 2. Discussion of the Related Art
[0004] FIG. 1 very schematically shows a conventional integrated
circuit testing system.
[0005] A testing device generally includes a test head 1 connected,
by wire links (not shown), to a programmable control system (not
shown) that can generate test signals and process, in return,
informations received from the test head.
[0006] Head 1 includes, in a free surface, directed to an
integrated circuit 2 to be tested, contact making protruding rods
3. Rods 3 are meant to ensure an electric contact with a printed
circuit wafer 4 forming an electric interface between rods 3 of
head 1 and a tip board 5. Tips 5' and rods 5" are meant to transfer
contacts from interface 4 to an integrated circuit chip 2.
[0007] The function of tip board 5 is to connect contacts (not
shown) of an integrated circuit chip 2 with a given spacing,
depending on the type of chip involved, to contacts (not shown) of
a front surface of printed circuit wafer 4 which are not
necessarily at the same spacing as the contacts of chip 2. Board 5
then generally includes deformable or supple tips 5' having great
length.
[0008] The function of printed circuit wafer 4 is to transfer its
front surface contacts to contacts of its rear surface which are
located facing rods 3 of the test head.
[0009] The pattern of the rear surface contacts of wafer 4 thus
depends on the test head while the pattern of the front surface
contacts depends on the type of chip to be tested.
[0010] Generally, rods 3 of test head 1 and/or rods 5" of board 5
are telescopic and fitted with springs.
[0011] It should be noted that designations "front surface" and
"rear surface" of wafer 4 are used here by mere convention and are
not meant to be limiting. Wafer 4 is thus provided, on each of its
surfaces, with conductive tracks and includes vias of contact
transfer from one surface to the other.
[0012] The testing of integrated circuit chips is generally
performed in batches on semiconductive wafers 6, for example made
of silicon. The wafers are successively brought on a test plate 7
and the chips 2 of each wafer 6 are successively brought above tips
5' of board 5 to perform the testing of the concerned chip.
[0013] Generally, all test procedures, that is, both the generation
and the processing of the electric signals, and the displacement of
wafers 6 as well as the passing from a wafer to the next one in the
same batch, are automated.
[0014] Rods 3 of the test head are generally distributed by blocks
8 at the periphery of the lower surface of the test head to face
peripheral areas of wafer 4. Peripheral blocks 8 are generally used
to carry low frequency signals (in particular, the supply signals),
and additional rods (not shown) for carrying high frequency signals
are generally provided in the central portion of the test head.
[0015] Since a test head is meant to test different types of chips,
interface wafer 4 and tip board 5 are removable, and one wafer 4
and one tip board 5 are available for each type of chip 2.
[0016] A problem which arises in this type of testing device is
associated with removably maintaining a given interface wafer 4 in
position of association with the test head.
[0017] A ring 9 for tightening a wafer 4 against head 1 is
generally used. Such a ring is generally formed by a generally
cylinder-shaped collar, a lower edge 10 of which, directed towards
its center, forms a support for the periphery of a wafer 4
positioned inside the collar. Opposite to edge 10, collar 9
comprises punctual protrusions 11 directed towards the inside.
Protrusions 11 are meant to cooperate with cams 12 protruding from
the external periphery of test head 1 to cause, by a rotating
motion of ring 9, a blocking of wafer 4.
[0018] For the wafer to maintain a correct position with respect to
rods 3 despite the rotating motion of ring 9, wafer 4 generally
includes bores (not shown) for cooperating with the positioning
rods (not shown) protruding from the lower surface of test head
1.
[0019] The distance separating test head 1 from wafer 4 is
generally adjusted by means of shims 13 interposed between the rear
surface of wafer 4 and the lower surface of head 1.
[0020] A problem which arises, upon assembly of a printed circuit
wafer 4 on a test head 1, is that the tightening performed by means
of ring 9 tends to cause a bending of wafer 4, as illustrated in
FIG. 1. Such a deformation of wafer 4 risks breaking the conductive
tracks of this wafer and risks bad contact with rods 3 of the test
blocks, especially for high frequency contacts performed in the
central portion of the wafer.
[0021] Further, the flexing of interface wafer 4 is transmitted to
the connection between the front surface of wafer 4 and tip board
5.
[0022] FIGS. 2A and 2B partially show, respectively, in
cross-sectional view associated with a wafer 4 and in top view, an
assembly ring 9' according to a conventional solution to solve this
problem of flexing of the interface wafer.
[0023] This solution consists of enlarging edge 10 supporting wafer
4 so that this edge extends to the center of the wafer, beyond
above rods 3 of peripheral blocks 8 of test head 1. The assembly
ring being generally a metal ring, isolating shims 14 are then
provided on the internal surface of edge 10 to prevent an electric
contact with tracks of the front surface of wafer 4.
[0024] A drawback of this solution is that the friction caused by
the rotation of ring 9' upon assembly of a wafer 4 causes a quick
wearing out of the interface wafer and damages its front surface
conductive portions.
[0025] Another disadvantage of conventional tightening rings such
as shown in FIGS. 1 and 2 is that the assembly of the ring on test
head 1 requires the use of a tightening tool due to the friction
between edge 10 and wafer 4 (FIG. 1) or to the friction between
shims 14 and wafer 4 (FIG. 2).
SUMMARY OF THE INVENTION
[0026] The present invention aims at providing a novel assembly
ring for an interface wafer on a test head which at least overcomes
the drawbacks of the above conventional solutions.
[0027] The present invention also aims at providing an assembly
ring which avoids any bending of the printed circuit wafer while
extending its lifetime.
[0028] The present invention also aims at providing a novel ring
which facilitates the assembly of a wafer on a test head.
[0029] The present invention aims, in particular, at providing an
assembly ring which suppresses any friction between an interface
wafer and the ring.
[0030] To achieve these and other objects, the present invention
provides an assembly ring, on a test head, of a wafer that provides
an interface of electric contact transfer between the test head and
a circuit to be tested, including a disk, open in its central
portion and meant for supporting the periphery of the wafer; a
removable collar assembly of the ring on the test head; and means
for rotatably connecting the disk in the vicinity of a free end of
the collar.
[0031] According to an embodiment of the present invention, the
rotatable connection means are formed of a ball bearing.
[0032] According to an embodiment of the present invention, the
disk includes insulating pads for receiving the periphery of the
wafer.
[0033] According to an embodiment of the present invention, the
pads are formed by concentric rings attached to the upper surface
of the disk.
[0034] According to an embodiment of the present invention, the
wafer is a printed circuit wafer.
[0035] According to an embodiment of the present invention, the
assembly ring is meant for a head for testing integrated circuit
chips.
[0036] According to an embodiment of the present invention, the
assembly ring is meant for an integrated circuit test head.
[0037] The present invention also aims at providing an integrated
circuit testing device, of the type including a test head for
receiving, removably, a printed circuit wafer that provides an
interface of electric contact transfer between the test head and an
integrated circuit to be tested, including a removable ring
assembly on the test head such as hereabove.
[0038] The foregoing objects, features and advantages of the
present invention will be discussed in detail in the following
non-limiting description of specific embodiments made in connection
with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] FIGS. 1, 2A, and 2B, previously described, are meant to show
the state of the art and the problem to solve;
[0040] FIGS. 3A and 3B partially show, respectively in
cross-sectional view and in top view, an embodiment of an assembly
ring according to the present invention; and
[0041] FIG. 4 is an enlarged view of a detail of an assembly ring
such as shown in FIGS. 3A and 3B.
DETAILED DESCRIPTION
[0042] The same elements have been referred to with the same
references in the different drawings. For clarity, the
representations of the drawings are not to scale and only those
elements necessary for the understanding of the present invention
have been shown in the drawings and will be described
hereafter.
[0043] A characteristic of the present invention is to implement
assembly ring of an interface wafer for an integrated circuit chip
test head in two portions rotatably connected to one another.
[0044] FIGS. 3A and 3B show, respectively in cross-sectional view
and in top view, an assembly ring 9" according to an embodiment of
the present invention.
[0045] According to the present invention, ring 9" is formed by a
collar 15 of substantially cylindrical general shape (partially
shown in FIGS. 3A and 3B) and of a disk 16, open at its center and
rotatably connected to collar 15. Disk 16 forms a surface for
supporting the periphery of a printed circuit wafer 4 (FIGS. 1A and
2B) forming an interface between a test head (not shown) and a tip
board for transferring contacts of a chip of a circuit to be
tested.
[0046] The general shape of an assembly ring 9" according to the
present invention is similar to that of a ring (9', FIG. 2A) of the
second conventional example of implementation, to be able to adapt
to an existing test head. Thus, the end of collar 15, opposite to
perforated disk 16, is provided with internal protrusions (not
shown in FIGS. 3A and 3B) for cooperating with cams of the test
head to tighten the ring on the head by a rotating motion.
[0047] According to the present invention, the rotatable link
between collar 15 and disk 16 is provided to generate as little
friction as possible. In the embodiment shown, this link is
provided by means of a ball bearing 18.
[0048] The ball race is circular and is, preferably, realized in a
set-back 19 of the surface of collar 15 meant for receiving the
external periphery of disk 16. A specific embodiment of the
rotatable link of disk 16 to collar 15 will be described in
relation with FIG. 4.
[0049] Collar 15 and disk 16 will preferably be made of metal, to
give them a resistance adapted to the mechanical constraints that
they undergo when associated with a test head. Pads 20, for
example, insulating pads, meant to bear the printed circuit wafer,
are preferably arranged in the upper surface of disk 16. These pads
20 are, preferably, circular and concentric (FIG. 3B) and are, for
example, made of epoxy glass. Thus, pads 20 electrically insulate
the printed circuit wafer from its support formed by disk 16, if
the disk is made of metal.
[0050] Of course, the size of central opening 17 of disk 16 is
sized so that the internal periphery of disk 16 extends, towards
the center of the disk, beyond above the conductive rods (3, FIG.
1) of the peripheral blocks (8, FIG. 1) of the test head, in order
to avoid any bending of the printed circuit wafer when assembled on
the test head.
[0051] The assembly of an interface wafer is performed by
positioning the wafer in ring 9", bringing ring 9" in a position of
introduction between the cams of the test head and giving the ring
a rotating motion to block it on the test head.
[0052] An advantage of the present invention is that, during the
tightening of ring 9" which is performed by a rotation of collar
15, disk 16 supporting the interface wafer does not rotate thanks
to ball bearing 18. Thus, any friction between the interface wafer
and its support 16 is avoided.
[0053] Another advantage of the present invention is that by
eliminating this friction, the assembly of the ring on the test
head does not require the use of a tightening tool and can be
performed manually.
[0054] FIG. 4 shows, in cross-sectional view, a detail of an
assembly ring 9" according to the present invention.
[0055] According to the embodiment shown, collar IS comprises, in
the vicinity of its free end of reception of disk 16, an internal
set-back 19. This set-back 19 is meant to receive a peripheral edge
21 of disk 16, perpendicular to the disk plane and provided at its
free end with a peripheral shouldering 22 directed to the outside.
Edge 21 and its shoulder 22 engage in set-back 19 and shoulder 22
defines, with the free end of collar 15, a housing that receives a
ball race 23 formed by a ring having an adapted section, for
example, an L-shaped section. Balls 18 are arranged on ball race 23
which is closed by means of a ring 24 likely to be attached, for
example, by means of screws 25, in the free end of collar 15. Ring
24 has, for example, a square-shaped cross-section, a first branch
of which is provided with screw reception bores 25, and extends to
edge 21 of disk 16 to enclose balls 18. A second branch of ring 24
is parallel to the edge of disk 16.
[0056] In the example shown in FIG. 4, collar 15 is formed by a
first reception portion 15' of disk 16 and of a second portion 15"
including the means of cam connection to the test head. The two
portions are then assembled, for example, by threaded joint 26.
[0057] It should however be noted that the present invention
applies whatever the shape and the mode of connection of the
assembly ring to the test head. Indeed, the connection of disk 16
forming an interface wafer support is performed at the free end of
the ring so that the implementation of the present invention, to
rotatably connect a disk 16 to a collar 15 of an assembly ring,
does not at all modify the rest of the assembly ring.
[0058] Thus, an advantage of the present invention is that it
requires no modification of the test head. Further, in the case of
an assembly ring conventionally formed of two portions, the ring
portion, meant to be connected to test head 1, can be kept by
adapting thereto a collar 15 associated with a disk 16 according to
the present invention.
[0059] To adapt an assembly ring according to the present invention
to existing test devices, it will however be provided that the bulk
of the ball bearing is adapted accordingly.
[0060] Of course, the present invention is likely to have various
alterations, modifications, and improvements which will readily
occur to those skilled in the art. In particular, the ball bearing
of rotatable connection of a disk to a collar according to the
present invention can be replaced with any sliding connection
means, provided that these means respect the described
functionalities. Further, other materials than those indicated
hereabove as an example can be used to implement the different
elements that provide an assembly ring according to the present
invention. Further, although the present invention has been
described in relation with an integrated circuit chip testing
system, it should be noted that the assembly ring according to the
present invention can easily be transposed to a device of testing
of bare or wired printed circuits, in which a wafer of interface
between a test head and a contact transfer tip board is used.
[0061] Such alterations, modifications, and improvements are
intended to be part of this disclosure, and are intended to be
within the spirit and the scope of the present invention.
Accordingly, the foregoing description is by way of example only
and is not intended to be limiting. The present invention is
limited only as defined in the following claims and the equivalents
thereto.
* * * * *