Feinmetall Exhibit 2004
`FormFactor, Inc. v. Feinmetall, GmbH
`IPR2019-00082
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`US 6,515,496 B2
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`1
`MICROSTRUCTURE TESTING HEAD
`
`TECHNICAL FIELD
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`invention relates to a testing head for
`The present
`microstructures, and, more particularly, the invention relates
`to a testing head for use on semiconductor integrated
`devices, and a method of making the microstructure testing
`heads.
`
`BACKGROUND OF THE INVENTION
`
`A testing head is essentially a device adapted to electri-
`cally interconnect a number of contact pads of a microstruc-
`ture with corresponding paths of a measuring machine
`employed to carry out the testing.
`The circuit testing procedure is used to detect any faulty
`integrated circuits directly at the manufacturing stage of the
`circuits. Testing heads are generally employed to electrically
`test the integrated circuits on the wafer itself before the
`circuits are separated and inserted into a chip package.
`A testing head comprises one or more pairs of parallel
`guide plates placed a given distance apart (to leave an air
`space therebetween), and a set of special movable contact
`elements. The pair of guide plates consists of a top guide
`plate and a bottom guide plate, both of which are formed
`with guide holes for the movable contact elements to be
`passed therethrough. The individual contact elements are
`typically small wires made of special alloys with good
`electrical and mechanical properties. These contact elements
`will be referred to as “probes” or “contact probes” through
`the remainder of this specification, to highlight the function
`that they serve.
`A good contact between the probes and the contact pads
`of a device under test is achieved by keeping the testing head
`pressed against
`the device, with the probes bending or
`flexing in the air gap between the guide plates. Testing heads
`of this type are commonly known as “vertical probes”.
`The amount of bending undergone by the probes, and the
`force required to produce the bending, is related to a number
`of factors, including the physical characteristics of the alloy
`used to make the probes, and an amount of offset between
`the guide holes in the top plate and the corresponding guide
`holes in the bottom plate, as well as other factors.
`Excessive bending of the probes should be avoided,
`however, because a probe may be flexed too much and not
`return to its original shape, or may otherwise become stuck
`in the guide holes.
`It should be noted that, for the testing head to perform
`satisfactorily, the probes must be allowed an amount of axial
`play in the guide holes. Thus, if a single probe breaks, the
`broken probe can be removed and replaced, without the need
`to replace the entire testing head.
`These factors should be taken into account when manu-
`
`facturing the testing head, because a good electric connec-
`tion between the probes and the device under test is man-
`datory.
`In some cases, the contact probes are aflixed to the top
`guide plate of the testing head in a permanent manner. This
`is known as a clamped probe testing head. However, testing
`heads with loose-mounted probes are more frequently used,
`where the probes are electrically connected to a “board” by
`a microcontact interface called the “space transformer”. This
`is known as a loose probe testing head.
`In the latter case, each contact probe has a second
`contacting tip opposite the one used to contact the device
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`under test. This second contacting tip is aimed at one of the
`contact pads on the space transformer. A good electric
`contact is established between the probes and the space
`transformer in a similar way as the contact to the device
`being tested, i.e., by pressing the probes against the contact
`pads on the space transformer.
`One advantage of a loose probe testing head is that one or
`more faulty probes, or the whole set of probes, can be
`replaced with greater ease than if clamped probe testing
`heads are used.
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`the top and bottom guide plates must be
`However,
`designed to hold the contact probes in place, even when no
`device is abutting their contacting tips for testing, or when
`the whole set of probes is moved during a replacement
`operation.
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`SUMMARY OF THE INVENTION
`
`Embodiments of the invention provide a testing head for
`microstructures that makes firm electric contact with a
`
`device under test, holds the probes securely in their guides,
`and minimizes the likelihood of bent probes becoming stuck
`in their guides.
`Presented is a device that has contact probes whose
`contacting tips meet the contact pads under a non-zero pitch
`angle and scrub their surfaces the moment a device to be
`tested is drawn against the contacting tips, thereby causing
`the contact probes to bend within an air gap. Additionally
`presented is a method of creating an electro/mechanical
`connection between a microstructure testing head and a
`device to be tested.
`
`The features and advantages of a testing head according
`to the invention will be apparent from the following descrip-
`tion of embodiments thereof, given by way of non-limiting
`examples with reference to the accompanying drawings.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a cross-sectional view of a testing head accord-
`ing to an embodiment of the invention.
`FIG. 2 is a diagram illustrating mechanical aspects of the
`operation of the testing head of FIG. 1.
`FIG. 3 is a cross-sectional View of a testing head accord-
`ing to a second embodiment of the invention.
`FIGS. 4A and 4B are a diagrams illustrating mechanical
`aspects of the operation of the testing head of FIG. 3.
`FIG. 5 is a cross-sectional detailed View of a testing head
`according an embodiment of the invention.
`FIG. 6 is a diagram of a clamped-probe testing head.
`FIGS. 7 and 8 are diagrams of loose-probe testing heads.
`FIG. 9 is a diagram illustrating a replacement operation in
`a testing head like that shown in FIGS. 7 and 8.
`FIG. 10 is a cross-sectional View of a guide for a testing
`head according to an embodiment of the invention.
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`
`With reference to FIG. 1, a testing head 1 according to an
`embodiment of the invention is shown. The testing head 1
`includes a top guide plate 2 and a bottom guide plate 3. Atop
`guide hole 4 is formed in the top guide plate 2, and a bottom
`guide hole 5 is formed in the bottom guide plate 3. Although
`for clarity only one set of guide holes 4, 5 and one contact
`probe 6 is shown, typically a testing head includes several
`contact probes, for example between 10 and 3000. The
`invention is equally applicable to testing heads having any
`number of contact probes.
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`Acontact probe 6 passes through the top guide hole 4 and
`the bottom guide hole 5. The contact probe 6 has a first
`section 6a near the top guide hole 4, a second section 6b near
`the bottom guide hole 5, and at least one contacting end or
`tip 7. The tip 7 of the contact probe 6 is used to contact the
`device being tested. The other end of the contact probe is
`coupled to the testing device, in order to read signals from
`the device being tested through the contact probe, as will be
`discussed below. In operation of the testing head 1,
`the
`contacting tip 7 is brought to touch a contact pad 8 on a
`device under test, thus establishing a mechanical and elec-
`trical connection between the device and a testing apparatus
`(not shown). The testing head 1 represents the working end
`of the testing apparatus.
`When the contact tip 7 of the probe 6 properly touches the
`device, enough force is placed on the probe to cause it to flex
`or bend in an area of the probe located between the first
`section 6a and the second section 6b. Providing enough
`pressure to the probe 6 to cause it to bend ensures that a good
`mechanical and electrical connection is made between the
`
`tip 7 and the contact pad 8.
`The top and bottom guide plates, 2 and 3, are suitably
`separated by an air gap 9 to accommodate the bent portions
`of the contact probes 6. The top and bottom guide holes, 4
`and 5, are adequately sized to receive the contact probes 6.
`Advantageously, the contacting tip 7 of a contact probe 6
`is set to meet the contact pad 8 at a pitch angle (XOUT. This
`pitch angle (XOUT causes the contacting tip 7 to “scrub” the
`contact pad 8 as pressure is applied to the probe 6, so as to
`improve the electric contact established between the tip 7
`and the pad 8. Even if, for example, the pad 8 is soiled,
`oxidized, or otherwise inhibiting good electrical contact.
`Of course, the contacting tip pitch angle “our between
`the probe tip 7 and the contact pad 8 should be determined
`for optimum scrubbing effect and minimum resistance of the
`tip-to-pad contact, as well as to avoid the risk of the tip 7
`skidding off of the contact pad area and possibly causing
`damage to the device under test or to the testing head 1 itself.
`To provide a testing head 1 with contact probes 6 pitched
`at a suitable angle GOUT to the contact pad 8, different
`embodiments of the invention use a number of variations in
`
`the top and bottom guide plates of the testing head. For
`convenience of explanation, the same reference numerals
`will be used through the remainder of this description to
`designate substantially similar elements in the various
`embodiments of the invention. By way of example,
`the
`terms “horizontal” and “vertical” will be used in relation to
`
`the drawings, although complementary or other arrange-
`ments are possible.
`In a first embodiment, the testing head 1 has at least one
`guide plate formed with a crooked guide hole that is effec-
`tive to deform the contact probe 6 and set the contacting tip
`7 at a predetermined pitch angle crow. This arrangement
`will be hereinafter referred to as “constant scrub angle”
`because the contacting tip 7 is always held at a constant
`angle relative to the device being tested.
`In a preferred embodiment of the invention shown in FIG.
`1, the bottom guide plate 3 has an S-like shaped crooked
`bottom guide hole 5. The S-like shaped pattern is effective
`to set the contact probe 6 into a predetermined position by
`frictional engagement at a plurality of support points A, B,
`C and D on the interior of the bottom guide hole 5.
`Embodiments of the invention can also include a top
`guide hole 4 in the testing head 1 that holds the probe 6 at
`an angle somewhat slanted from vertical. This arrangement
`can facilitate a smoother bending of the probe 6 than if the
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`probe 6 is held perpendicular relative to the top guide plate
`2. Preferably, the angle of the guide hole 4 through the top
`guide plate 2 may be offset from perpendicular between
`about 0 to 10°, but may be any angle that facilitates the
`proper bending of the probe 6. In some instances the best
`perpendicular offset angle may need to be determined by
`trial and error. The probe 6 may be attached to the guide
`plate 2 in a firmly held or a sliding fit.
`Alternatively, the top guide plate 2 could be formed with
`an S-like shaped crooked top guide hole 4, and not the
`bottom guide hole 5, or both the top and bottom guide plates
`2, 3 could be formed with S-like shaped crooked guide holes
`4, 5. Furthermore, differently shaped crooked guide holes
`could be provided, such as curvilinear holes, still providing
`a number of points of support. As used in this description,
`“crooked” is meant to describe any form of guide hole that
`is non-straight, including those holes with one bend, such as
`a “C” shape, two bends, such as an “S” shape, or any number
`of bends, such as a “stairstep” profile, as well as others.
`Additionally, the guide holes 4, 5 in the guide plates 2, 3,
`may have smooth shaped bends (referred to herein as
`“curveline ar”, no matter how many bends the hole includes),
`such as that shown in FIG. 1, or they could be rather abrupt,
`such as those possible to be made by having a guide plate
`formed by multiple layers, shown in FIG. 10 and discussed
`below.
`
`The mechanical aspect of the operation of a constant
`scrub angle type of the testing head 1, having top 2 and
`bottom 3 guide plates formed with crooked guide holes, is
`as described herein below.
`
`A device under test properly drawn against the testing
`head 1 will produce “overtraver” of the contact probe 6 in
`the air gap 9, meaning that downward force is applied to the
`top of the contact probe 6 while keeping the device steady,
`or upward force is applied to the bottom tip 7 of the contact
`probe 6 by the device under test while keeping the top guide
`plate 2 steady, in excess of that merely necessary to make an
`initial contact between the contact pad 8 and the probe tip 7.
`This overtravel will cause the probe 6 to bend. But the
`support points A, B, C and D bind the movement of the
`contacting tip 7 to a constant pitch angle (10m to the contact
`pad 8. Thus, an upward movement or overtravel of the
`contact probe 6 is accompanied by a horizontal or scrubbing
`movement of the contacting tip 7, over the contact pad 8,
`with the pitch angle (XOUT being held constant, as shown
`schematically in FIG. 2. In other words, a desired scrubbing
`action can be achieved by suitably adjusting the pitch angle
`010117 and the amount of overtravel of the contacting tip 7.
`In another modification, the testing head 1 has at least one
`guide plate 2, 3 formed with non-vertical guide holes 4, 5
`that deflects the contact probe 6 within the air gap 9 and
`shifts the other guide plate in the horizontal direction in
`order to force a bend in the contact probe 6 and set its
`contacting tip 7 at a predetermined pitch angle crow. This
`arrangement will be referred to as “variable scrub angle”
`hereinafter, because the angle at which the contacting tip
`meets the contact pad 8 will change as the contact probe 6
`flexes in the air gap 9.
`In an embodiment of the invention shown in FIG. 3, the
`top guide plate 2 has a straight non-vertical top guide hole
`4, and the bottom guide hole 5 in the bottom guide plate 3
`does not have the same angle deflection. Additionally, the
`guide holes 4 and 5 may be horizontally shifted relative to
`one another, for example, between 1 um and 4 mm, and,
`more preferably, between 1 um and 1.5 mm. This arrange-
`ment forces a bend in the contact probe 6 and pitches its
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`contacting tip 7 at an angle Glow relative to the contact pad
`8. The contact probe 6 has at least two support points E, F
`in the bottom guide hole 5, as shown in FIG. 3. The probe
`6 can either be a sliding fit or held firmly in the top guide
`hole 4. Having the top guide hole 4 lie non-perpendicular to
`the top guide plate 2 encourages the contact probe 6 to bend,
`and keeps the bent section of the probe 6 constrained within
`the air gap 9.
`The mechanical aspects of the operation of a variable
`scrub angle type testing head 1, having a top guide plate 2
`formed with non-vertical holes and a bottom guide plate 3
`adapted to be shifted relative to the top guide plate 2 in the
`horizontal direction, is as described herein below.
`A device under test, drawn against the testing head 1,
`produces “overtravel” of the contact probe 6 in the air gap
`9, so that the probe is bent. This is similar to the constant
`scrub angle type testing head 1, described above. In this
`case, where the testing head 1 has a variable scrub angle,
`however, the movement of the contacting tip 7 of the probe
`6 is not required to maintain a constant pitch angle “our
`relative to the contact pad 8. The tip 7 moves progressively
`into a vertically upright position over the pad 8, and in so
`doing, the tip 7 scrubs the pad 8 as shown in FIGS. 4A and
`4B. Once the bending force of the probe 6 is released (for
`instance by removing the device under test), the probe 6 can
`drop smoothly through the bottom guide hole 5 into its initial
`position.
`In particular, as shown in FIG. 4A, the contact pad 8 of the
`device under test is brought in contact with the probe 6. As
`the probe 6 flexes as indicated in FIG. 4A,
`the friction
`arrangement of the support points E and F in the bottom
`guide hole 5 also causes the probe tip 7 to scrape the contact
`pad 8, as the probe 6 continues to flex into the shape as
`shown in FIG. 4B. The ending position of the probe 6,
`because the probe is nearly vertically aligned in the bottom
`hole 5, effectively prevents the probe 6 from becoming stuck
`in the bottom guide hole 5.
`In a further modification of the guide plates, which is
`useful with both of the above arrangements, a film 10 of an
`elastic material is provided, as shown in FIG. 5, on either the
`top or bottom guide plates, or both, to hold the probes more
`positively inside their corresponding top and bottom guide
`holes, yet still maintaining a sliding fit arrangement.
`In addition,
`the elastic material film 10 contributes to
`prevent the probe from sticking in the guide holes by virtue
`of the elastic bias that it applies to the probes as these are
`bent against the film. In particular, the elastic bias from the
`film facilitates the probe 6 retraction from the holes 4 or 5
`as the bending force is removed.
`As discussed previously, the contact probes 6 may be
`fixedly mounted on the testing head 1. For that purpose, the
`top guide plate 2 would securely hold a plurality of long
`wires in the top guide holes 4, e.g. bonded therein with a
`resin, or some other suitable material. The long wires
`continue through the top guide holes 4 and are convention-
`ally soldered at a bond 20 to a board 11 of the testing head
`1, as shown in FIG. 6. This arrangement forms a clamped
`probe testing head.
`It should be noted that the foregoing arrangements could
`be used with loose-mounted probes as well, for example, as
`shown in FIG. 7. In that Figure, a microcontact interface 12,
`known as a “space transformer,” is itself electrically con-
`nected to the board 11. In this case, the contact probes 6 are
`attached neither to the bottom guide plate 3 nor to the top
`plate 2, and would be formed with additional contacting tips
`7a aimed at a plurality of contact pads 84: on the space
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`transformer 12. The electric contact of the probes with the
`space transformer may be established in the same way as the
`contact to the device under test, by urging the probes 6 onto
`the contact pads 8a of the space transformer, the latter being
`held away from the device under test by side spacers 13a and
`13b, as shown in FIG. 8. In particular, the contact pads 8a
`on the space transformer 12 are aligned with micrometric
`accuracy to the contacting tips 7A that jut out from the top
`guide plate 2. This yields a loose probe type testing head.
`The testing head 1 with loose-mounted contact probes 6
`allows the set of probes 6, sometimes referred to as a probe
`block 14, to be easily replaced. As shown in FIG. 9, one or
`more faulty probes 6 within the probe block 14 can be easily
`replaced, with no need for replacing soldered joints as would
`be required if the clamped probe testing head 1 of FIG. 6
`were instead used.
`
`In particular, with respect to FIG. 9, the contact probes 6
`in a probe block 14 may slide within their top 2 and bottom
`3 guide plates, but not completely out of the plates, on the
`occasion of a faulty contact probe 6 or the whole probe block
`14 being replaced, or when no device is abutting the testing
`head 1 for testing purposes.
`Advantageously, either of the previously discussed
`arrangements, i.e. the constant scrub angle or the variable
`scrub angle arrangements, could be applied to a testing head
`1 with loose mounted contact probes 6. In this case,
`in
`addition to an improved electric contact between the probes
`6 and the device under test from the scrubbing action of the
`contacting tips 7, a frictional resistance is created between
`the guides 4, 5 and the probes 6, effective to stop the contact
`probes 6 from slipping out while the probes 6 or the probe
`block 14 are being replaced, or when no device is abutted
`against the testing head 1 for testing.
`Accordingly, guide plates formed with crooked guide
`holes, in particular holes having an S-like pattern, can be
`used, and the guide plates be suitably offset in the horizontal
`direction to force a deformation in the contact probe, thereby
`ensuring that the probe will stay in place even while probes
`or probe blocks are being replaced, or no device is abutting
`the head for testing.
`This effect can also be achieved using a film of an elastic
`material 10, to be applied preferably on the inner face of the
`top guide plate. With the elastic material 10 so applied, the
`film is formed with contact probe clearance holes having a
`smaller diameter than the corresponding guide holes, so that
`the probes 6 will be retained within the guide holes 4, 5 by
`the slight frictional drag created between the film 10 and the
`probes.
`A further embodiment of a portion of this invention is
`shown in FIG. 10. Guide plates having crooked guide holes
`could be implemented in the form of stacks of thinner guide
`plates 22, laid in mutual contact to define a guide hole
`having a desired pattern, as shown schematically in FIG. 10.
`Changes can be made to the invention in light of the above
`detailed description. In general, in the following claims, the
`terms used should not be construed to limit the invention to
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`the specific embodiments disclosed in the specification and
`the claims, but should be construed to include all methods
`and devices that are in accordance with the claims.
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`Accordingly, the invention is not limited by the disclosure,
`but instead its scope is to be determined by the following
`claims.
`What is claimed is:
`
`1. A testing head for microstructures comprising:
`a top guide plate having a top guide hole formed there-
`through;
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`a bottom guide plate having a bottom guide hole formed
`therethrough, the bottom guide plate separated from the
`top guide plate by an air gap; and
`a contact probe having a contacting tip arranged to
`mechanically and electrically contact a contact pad of
`a test device as the test device is drawn against the
`contacting tip, wherein at least one of the guide holes
`in the guide plates is formed with a crooked shape that
`is structured to force the contact probe to bend in the air
`gap, and structured to force the contacting tip of the
`contact probe to the pitch angle (GOUT) that is non-
`perpendicular relative to the contact pad of the test
`device.
`
`2. The microstructure testing head of claim 1, wherein the
`at least one guide hole is structured to hold the contact probe
`firmly in a predetermined position by friction between the
`contact probe and a plurality of support points in the at least
`one guide hole.
`3. The microstructure testing head of claim 2, wherein the
`at least one guide hole has a curvilinear pattern.
`4. The microstructure testing head of claim 3, wherein the
`at least one guide hole is S-shaped.
`5. The microstructure testing head according to claim 2,
`wherein the guide plate containing the at least one crooked
`shape guide hole is formed of a plurality layers of material,
`and wherein edges of the plurality of layers of material form
`the plurality of support points.
`6. The microstructure testing head of claim 1, wherein the
`top guide hole and the bottom guide hole are horizontally
`shifted relative to each other.
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`7. The microstructure testing head of claim 6 wherein the
`top guide hole and the bottom guide hole are horizontally
`shifted relative to each other between about 1 micrometer
`and 3 millimeters.
`
`8. The microstructure testing head of claim 7 wherein the
`at least one of the guide holes is S shaped.
`9. The microstructure testing head of claim 7 wherein
`exactly one of the guide holes is crooked, and wherein the
`other of the guide holes is relatively straight, and formed
`non-perpendicular to its respective guide plate.
`10. The microstructure testing head of claim 1, further
`comprising:
`a plurality of top guide holes in the top guide plate,
`a plurality of bottom guide holes in the bottom guide
`plate; and
`a plurality of contact probes each insertable through a
`respective one of the top guide holes and one of the
`bottom guide holes.
`11. The microstructure testing head according to claim 1,
`further comprising a film of an elastic material applied to
`one or both of the guide plates.
`12. The microstructure testing head according to claim 1,
`wherein one or both of the guide plates are formed of a
`plurality of layers of material.
`13. A testing head for microstructures, comprising:
`a top guide plate having a top guide hole formed there-
`through;
`a bottom guide plate having a bottom guide hole formed
`therethrough, the bottom guide plate separated from the
`top guide plate by a gap; and
`a contact probe protruding through the top guide hole and
`the bottom guide hole and having a contacting tip;
`wherein at least one of the guide holes in the guide plates
`is formed with a crooked shape, and as a contact pad of
`a test device is placed against the contacting tip of the
`contact probe, the at least one crooked shape guide hole
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`causes the contacting tip to meet the contact pad at a
`non-perpendicular pitch angle relative to the contact
`pad, and causes the contacting tip to scratch a surface
`of the contact pad, and
`wherein the at least one crooked shape guide hole causes
`the contact probe to bend as the test device is further
`pressed against the contacting tip of the contact probe.
`14. The testing head of claim 13 wherein the testing head
`is structured to hold the contacting tip of the contact probe
`at a constant angle as the test device is further pressed
`against the contacting tip of the contact probe.
`15. The testing head of claim 14 wherein the at least one
`crooked shape guide hole causes the contact probe to be
`frictionally held within the at least one crooked shape guide
`hole in the non-perpendicular pitch angle relative to the
`contact pad.
`16. The testing head of claim 15 wherein the contact probe
`is frictionally held at a plurality of support points in the at
`least one crooked shape guide hole.
`17. The testing head of claim 15 wherein the at least one
`crooked shape guide hole has a curvilinear shape.
`18. The testing head of claim 17 wherein the at least one
`crooked shape guide hole has an S-shape.
`19. The testing head of claim 13 wherein the testing head
`is structured to allow the contacting tip of the contact probe
`to change the non-perpendicular pitch angle relative to the
`contact pad as the test device is further pressed against the
`contacting tip of the contact probe.
`20. The testing head of claim 19 wherein the top guide
`hole and the bottom guide hole are horizontally shifted
`relative to one another.
`
`21. The testing head of claim 19 wherein the top guide
`hole and the bottom guide hole are horizontally shifted
`relative to one another between about 1 micrometer and 4
`millimeters.
`
`22. The testing head of claim 13 wherein exactly one of
`the guide holes has a crooked shape and wherein the other
`guide hole is formed non-perpendicular to its respective
`guide plate.
`23. The testing head of claim 13, further comprising:
`a plurality of top guide holes in the top guide plate,
`a plurality of bottom guide holes in the bottom guide
`plate; and
`a plurality of contact probes each insertable through a
`respective one of the top guide holes and one of the
`bottom guide holes.
`24. The testing head of claim 13, further comprising a film
`of an elastic material applied to one or both of the guide
`plates.
`25. The testing head of claim 13 wherein one or both of
`the guide plates are formed by a plurality of layers of
`material.
`
`26. The testing head according to claim 13, wherein the
`guide plate containing the at least one guide hole is formed
`of a plurality layers of material, and wherein edges of the
`plurality of layers of material form the plurality of support
`points.
`27. A method for creating an electro/mechanical connec-
`tion between a microstructure testing head and a device to be
`tested, the method comprising:
`holding a contacting tip of a contact probe in the testing
`head at an angle non-perpendicular to a contact pad on
`the device to be tested, prior to a time when the contact
`pad touches the contacting tip, by holding a portion of
`the contact probe in a frictional relationship with a
`plurality of support points located in a crooked guide
`hole in a guide plate;
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`Page 9 of 11
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`9
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`10
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`US 6,515,496 B2
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`causing the contacting tip of the contact probe to scrape
`against the contact pad as the device to be tested is
`pressed against the contacting tip; and
`causing the contact probe to bend as the device to be
`tested is further pressed against the contacting tip.
`28. The method of claim 27 wherein the crooked guide
`hole is curvilinear.
`
`29. The method of claim 28 wherein the curvilinear guide
`hole is S-shaped.
`30. The method of claim 27 wherein the guide plate is
`formed from a plurality of layers of material.
`31. The method of claim 20 wherein the plurality of
`support points are made from edges of the plurality of layers
`of material.
`
`32. The method of claim 27, further comprising:
`the
`while the device to be tested is pressed against
`contacting tip and the contacting tip is scraping against
`the contact pad, allowing the contacting tip of the
`
`contact probe to change the angle of the contacting tip
`that was originally non-perpendicular to the contact
`pad.
`33. The method of claim 32, further comprising, before
`the contact pad touches the contacting tip:
`
`5
`
`0
`
`inserting the contact probe through a top guide hole in a
`top guide plate and a bottom guide hole in a bottom
`guide plate wherein the top guide hole and the bottom
`guide hole are not vertically aligned with one another.
`34. The method of claim 33, wherein at least one of the
`top guide hole and the bottom guide hole is not perpendicu-
`lar relative to its respective guide plate.
`35. The method of claim 33, further comprising applying
`5 a layer of elastic material to at least one of the top and
`bottom guide plates.
`
`1
`
`1
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`

`UNITED STATES PATENT AND TRADEMARK OFFICE
`
`CERTIFICATE OF CORRECTION
`
`PATENT NO.
`DATED
`INVENTOR(S)
`
`: 6,515,496 B2
`: February 4, 2003
`: Felici et a1.
`
`Page 1 of 1
`
`It is certified that error appears in the above-identified patent and that said Letters Patent is
`hereby corrected as shown below:
`
`Title gage,
`5/2001
`Item [56], References Cited, U.S. PATENT DOCUMENTS, “6,242,320 B1
`Haseyama et al.
`324/754” should read -- 6,229,320 B1 5/2001 Haseyama et al.
`324/754 ——; and “6,242,929B1
`6/2001 Mizuta 324/765” should read
`
`-- 6,242,929B1 6/2001 Mizuta 324/754
`
`Column 4,
`
`Line 33, “produce “overtraver” of’ should read -- produce “overtravel” of
`
`Column 9,
`
`Line 12, “The method of claim 20” should read —— The method of claim 30 ——.
`
`Signed and Sealed this
`
`Second Day of March, 2004
`
`mix/431
`
`Acting Director oft/1e United States Patent and Trademark Ofi‘iee
`
`JON W. DUDAS
`
`Page11of11
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`Page 11 of 11
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`