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`Feinmetall Exhibit 2015
`FormFactor, Inc. v. Feinmetall, GmbH
`IPR2019-00082
`
`Page 1 of 18
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`

`

`
`US. Patent
`
`
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`
`Jul. 27, 2004
`
`
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`
`
`Sheet 1 0f 11
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`US 6,768,327 B2
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`
`
` 7
`
`
`
`FIG. 1
`
`
`PRIOR ART
`
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` g
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`FIG. 2A
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`
`1
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`PRIOR ART
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`Page 2 of 18
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`Page 2 of 18
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`

`

`72L
`
`uIJ—-.|.|
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`./
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`Page 3 of 18
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`

`

`
`
`US. Patent
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`Jul. 27, 2004
`
`
`
`
`Sheet 3 0f 11
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`
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`US 6,768,327 B2
`
`
`
`
`FIG. 2C
`
`PRIOR ART
`
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`
`
`FIG. 2D
`
`PRIOR ART
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`PRIOR ART
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`
`FIG. 2E
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`PRIOR ART
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`FIG. 2F
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`Page 40f 18
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`Page 4 of 18
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`

`

`US. Patent
`
`Jul. 27, 2004
`
`Sheet 4 0f 11
`
`US 6,768,327 B2
`
`égdlfiar/
`
`nnnnnnnnnmumIH.............................................argig
`
`E
`
`F
`
`Pitchmin
`
`FIG. 4A
`
`Page 50f 18
`
`Page 5 of 18
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`

`

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`US. Patent
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`Jul. 27, 2004
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`
`
`
`Sheet 5 0f 11
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`US 6,768,327 B2
`
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`
`
`FIG. 4B
`
`[.lul.lll|||.l.|.|.lvl
`
`Vida/A
`fly,..........
`
`
`
`
`Pitchmin
`
`
`
`5....................................."gig
`
`
`If
`
`
`.1
`W”
`
`_IIIIIIIIIII
`
`
`
` .,.4...L___
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`llllll
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`
`___
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`__
`
`__u
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`
`-flm
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`Page 60f 18
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`Page 6 of 18
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`

`

`
`US. Patent
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`
`
`Jul. 27, 2004
`
`Sheet 6 0f 11
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`
`
`US 6,768,327 B2
`
`.......I
`
`
`
`
`
`
`
` F------E:-------
`
`
`Gl/IIIKI/IléI'll}unnuuuf31 In}-
` ww---al....._...........
`
`
`F(#£?rtrffifé.................I
`
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`Page 7 of 18
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`Pitchmin
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`
`
`
`FIG. 4C
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`Page 7 of 18
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`

`

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`US. Patent
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`Jul. 27, 2004
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`
`
`
`Sheet 7 0f 11
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`US 6,768,327 B2
`
`W'
`
`
`
`
`
`Vlfférg/fé
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`
`
`
`
`
`
`WW
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`43/19/5971.“
`
`II]
`
`Pitchmin
`
`
`FIG. 4D
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`Page 80f 18
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`Page 8 of 18
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`

`

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`US. Patent
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`Jul. 27, 2004
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`Sheet 8 0f 11
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`US 6,768,327 B2
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`FIG. 4E
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`Page 90f 18
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`Page 9 of 18
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`US. Patent
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`Jul. 27, 2004
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`Sheet 9 0f 11
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`US 6,768,327 B2
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`
`
`(\
`
`
`FIG. 4F
`
`\
`\ ,'\ \
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`x
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`_.1....._...._..,.-
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`Page 10of18
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`Page 10 of 18
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`US. Patent
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`Jul. 27, 2004
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`Sheet 10 0f 11
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`US 6,768,327 B2
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`
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`.
`
`100
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`
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`_
`
`FIG. 5
`
`100
`
`FIG. 6
`
`8”"
`
`/ 1
`
`4
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`Page11of18
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`Page 11 of 18
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`

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`US. Patent
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`Jul. 27, 2004
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`Sheet 11 0f 11
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`US 6,768,327 B2
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`
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`FIG. 8
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`Page 12 01:18
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`Page 12 of 18
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`

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`US 6,768,327 B2
`
`
`1
`TESTING HEAD HAVING VERTICAL
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`
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`PROBES FOR SEMICONDUCTOR
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`INTEGRATED ELECTRONIC DEVICES
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`BACKGROUND OF THE INVENTION
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`1. Field of the Invention
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`The present invention relates to a testing head having
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`vertical probes and used to test a plurality of semiconductor-
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`integrated electronic devices incorporating so called contact
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`pads.
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`2. Description of the Related Art
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`As is well known, a testing head is basically a device
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`suitable to electrically interconnect a plurality of contact
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`pads of a semiconductor-integrated electronic device and
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`corresponding channels of a testing machine arranged to
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`perform the tests.
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`Integrated electronic devices are factory tested in order to
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`spot and reject any circuits that show out to be already
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`defective during the manufacturing phase. The testing heads
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`are normally employed to electrically test
`the
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`semiconductor-integrated electronic devices “on wafer”,
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`before cutting and mounting them in a chip package.
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`Atesting head having vertical probes comprises at least a
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`pair of parallel plate-like holders placed at a given distance
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`apart to leave an air gap therebetween, and a plurality of
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`specially provided movable contact elements.
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`Each plate holder, referred to as a die in the art and
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`throughout this specification, is formed with a plurality of
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`through-going guide holes, each hole in one of the dies
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`corresponding to a hole in the other die and guiding a
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`respective contact element, or contact probe as the element
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`will be called through this specification and the appended
`claims, for sliding movement therein. The contact probes are
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`usually cut from wire stock of some special alloy having
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`good electrical and mechanical properties.
`A good electrical connection of the testing head contact
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`probes to the contact pads of an integrated electronic device
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`to be tested is achieved by urging each contact probe onto
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`the respective contact pad. This results in the movable
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`contact probes becoming flexed in the air gap between the
`two dies.
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`Testing heads of this type are commonly known as
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`“vertical probes”.
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`Briefly, known testing heads have an air space where the
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`probes are allowed to flex, such a flexion action being
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`eventually assisted by suitable design of the probes or their
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`dies, as shown schematically in FIG. 1.
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`As shown in FIG. 1, a testing head 1 comprises at least an
`upper die 2 and a lower die 3, both dies being formed with
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`through-going upper guide hole 4 and lower guide hole 5,
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`respectively, in which at least one contact probe 6 slides.
`The contact probe 6 has a contact end or tip 7.
`In
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`particular, the contact tip 7 is caused to abut against a contact
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`pad 8 of an integrated electronic device to be tested, thereby
`establishing an electrical contact between said device and a
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`testing apparatus (not shown) that has said testing head as
`end element.
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`The upper and lower dies 2 and 3 are suitably separated
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`by an air space 9 in which the contact probes 6 are allowed
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`to deform or flex in normal operation of the testing head, i.e.
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`upon the testing head coming in contact with the integrated
`electronic device to be tested. The upper and lower guide
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`holes 4 and 5 are both sized to guide the contact probe 6.
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`Page 13 of18
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`FIG. 1 schematically shows a testing head 1, which
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`mounts loose-fitting probes and is associated with a micro-
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`contact strip or space transformer shown schematically at
`10.
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`In this case, each contact probe 6 has another contact tip
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`toward a plurality of contact pads 11 of the space trans-
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`former 10. The electric connection of the probes to the space
`transformer 10 is assured same as the connection to the
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`integrated electronic device to be tested, i.e. by urging the
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`probes 6 onto the contact pads 11 of the space transformer
`10.
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`Amajor advantage of a testing head 1 with loose-mounted
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`contact probes is that one or more faulty probes 6 in the set
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`of probes, or the whole set, can be replaced more conve-
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`niently than in testing heads that have fixed probes.
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`In this case, however, the upper and lower dies 2 and 3
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`should be designed to ensure that the contact probes 6 will
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`be held in place even when no integrated electronic device
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`is abutting their contact tips 7 for testing, or when a probe
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`set is removed for replacement purpose.
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`The deformed pattern of the probes and the force needed
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`to produce the deflection depend on several factors, namely:
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`the distance between the upper and lower dies;
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`the physical characteristics of the alloy from which the
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`probes are formed; and
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`the amount of offset between the guide holes in the upper
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`die and the corresponding guide holes in the lower die,
`as well as the distance between such holes.
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`It should be noted that, for the testing head to perform
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`properly, the probes should be allowed a suitable degree of
`free axial movement within the guide holes. In this way, the
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`probes can also be taken out and replaced individually in the
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`event of a single probe breaking, with no need to replace the
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`whole testing head.
`to be taken into due
`All these features are, therefore,
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`account in the manufacture of a testing head, given that a
`good electric connection between the probes and the device
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`to be tested is mandatory.
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`Also known is to use contact probes having a pre-
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`deformed shape even when the testing head 1 is not con-
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`tacting the device to be tested, as in the probes 6b, 6c and 6d
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`shown in FIG. 2A. The pre-deformed shape effectively helps
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`the probe to correctly flex during its operation, i.e. upon
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`contacting the integrated electronic device to be tested.
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`Conventional testing heads inherently place limits on the
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`distance to be lowered between two adjacent probes 6, while
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`the technological development and the chip miniaturization
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`continuously press to reduce the distance between centers of
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`two contact pads 8 of an integrated electronic device to be
`tested, this distance being known as the pitch distance of the
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`pads.
`Thus, a minimum pitch, in the sense given above, will be
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`dependent on the layout and the dimensions of the probes 6,
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`according to the following relation:
`Pitchmin=E+2Amin+Wmin
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`where Amin=(F—E)/2 and where, as shown in FIG. 2B,
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`which is a sectional view through part of a testing head 1
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`according to the prior art:
`Pitchmin is the minimum pitch or distance between
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`centers of two adjacent contact pads 8 of the integrated
`electronic device to be tested;
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`E is the dimension of the cross-section of the probe 6. For
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`example, in probes having a circular cross-sectional
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`shape, the dimension used for computing the minimum
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`Page 13 of 18
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`US 6,768,327 B2
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`pitch would be the cross-section diameter value of the
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`probe 6, where the probe has a square cross-sectional
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`shape, while in probes having a rectangular cross-
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`sectional shape, the dimension used for computing the
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`minimum pitch would be the minor side or the major
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`side of the rectangular cross-section of the probe 6,
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`depending on the chosen arrangement for positioning
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`the contact probes;
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`In particular, FIGS. 2C, 2D, 2E and 2F are top plan views
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`of a testing head portion comprising contact probes 6 having
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`a circular cross-sectional shape (FIG. 2C), a square cross-
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`sectional shape (FIG. 2D) and a rectangular cross-sectional
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`shape (FIGS. 2E and 2F, in mirrored configurations) respec-
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`tively.
`Amin is the minimum distance between a probe 6 and its
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`guide holes 46 5 that allows the probe to slide freely in
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`the guide holes 4, 5 during normal operation of the
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`testing head;
`Wmin is the minimum wall thickness allowable between
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`one guide hole 4, 5 and the following, in order to
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`guarantee the testing head 1 to be an adequately strong
`structure; and
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`F is the dimension of the cross section of a guide hole 4.
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`Current vertical technologies, usually with circular cross-
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`sectional shaped probes, achieve a reduction of the pitch
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`value by reducing the dimensions, and especially reducing
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`the minimum dimension E (being the minimum diameter for
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`probes having a circular cross section) of the probes 6. The
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`other factors in the above relation are set practically by
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`technological limitations to the manufacture of the testing
`head.
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`BRIEF SUMMARY OF THE INVENTION
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`An embodiment of this invention provides testing heads
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`for microstructures, which comprise probes designed to
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`deform upon coming in touch with contact pads in order to
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`establish a good electric connection to an integrated elec-
`tronic device to be tested, and adapted to allow a substantial
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`reduction in the distance between contact tips and thus a
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`reduction in the pitch distance between contact pads of
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`integrated electronic devices to be tested.
`One of the principles on which an embodiment of the
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`present invention stands is to provide a testing head with a
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`plurality of vertical probes having at least a rigid end portion
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`extending laterally with respect to the contact probe body.
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`Presented is a testing head having vertical probes and
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`comprising a first and a second plate-like holder provided
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`with respective guide holes a contact probe adapted to be
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`received in the guide holes and having a contact tip adapted
`to establish mechanical and electrical contact to a corre-
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`sponding contact pad of an integrated electronic device to be
`tested,
`the contact probe being deformed in a deflection
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`region located between the plate-like holders as the contact
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`tip abuts onto the contact pad wherein the contact probe
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`further comprises a rigid arm extending laterally from a
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`body of the contact probe and terminating in the contact tip,
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`the rigid arm being adapted to offset the contact point of the
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`contact probe with the corresponding contact pad with
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`respect to a longitudinal axis of the contact probe.
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`The features and advantages of the testing head according
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`to this invention will be apparent from the following
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`description of embodiments thereof, given by way of non-
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`limitative examples with reference to the accompanying
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`drawings.
`BRIEF DESCRIPTION OF THE SEVERAL
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`VIEWS OF THE DRAWINGS
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`FIG. 1 is a cross-sectional view of a testing head accord-
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`ing to an embodiment of the prior art;
`Page 14 of18
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`FIG. 2A is a cross-sectional view of a testing head
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`according to another embodiments of the prior art;
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`FIG. 2B is a cross-sectional view of a the testing head
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`according to the embodiment of FIG. 1;
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`FIGS. 2C to 2F are top plan views of a testing head
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`according to other embodiments of the prior art, comprising
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`probes having different shapes;
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`FIG. 3 is a cross-sectional view of a testing head accord-
`ing to an embodiment of the invention;
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`FIGS. 4A to 4F are top plan views of some layouts for
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`plural contact probes in the testing head according to the
`embodiment of FIG. 3;
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`FIGS. 5 and 6 are cross-sectional views of a testing head
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`according to further embodiments of the invention; and
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`FIGS. 7 to 9 are top plan views of different arrangements
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`contact probes-guide holes adapted to raise the frictional
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`drag between them in a testing head according to other
`embodiments of the invention.
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`DETAILED DESCRIPTION OF THE
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`INVENTION
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`With reference to FIG. 3, a testing head according to an
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`embodiment of the invention, designed for contacting an
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`electronic integrated device to be tested, is shown generally
`at 100 in schematic form.
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`For simplicity, only the testing head portion that com-
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`prises two plate-like holders or dies for the movable contact
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`probes is shown, it being understood that the testing head
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`according to the embodiments of invention could accom-
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`modate a range of different dies and movable probes.
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`The testing head 100 has an upper die 12A and a lower die
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`12B, both formed with guide holes 13A, 13B, respectively,
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`and adapted to receive a contact probe 14.
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`The contact probes 14 have contact tips 15 arranged to
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`abut onto a plurality of contact pads 16 of an electronic
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`integrated device, shown schematically at 17, to be tested.
`In the embodiment of FIG. 3,
`the testing head 100 is
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`shown to include loose-mounted probes that have a further
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`contact tip 18 at another end for contacting a micro-contact
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`strip or space transformer 19. This is given by way of
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`non-limiting example of a testing head according to an
`embodiment of the invention.
`It should be understood,
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`however, that the testing head 100 could be provided with
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`fixed probes instead.
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`Advantageously according to an embodiment of the
`invention, each contact probe 14 is formed with a rigid arm
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`20, extending laterally from a body 21 of the probe 14. In
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`particular, the rigid arm 20 extends along a perpendicular or
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`otherwise sloping direction with respect to the probe 14, i.e.
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`has a longitudinal axis B—B lying perpendicularly or at an
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`angle to a longitudinal axis A—A of the contact probe 14.
`The arm 20 is terminated with the contact tip 15 of the probe
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`14 for abutting the contact pads 16 of the electronic inte-
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`grated device 17 to be tested.
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`Accordingly, the point where the tip 15 of the probe 14
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`meets the pad 16 will be offset from the longitudinal axis
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`A—A of the probe 14.
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`Advantageously according to an embodiment of the
`invention, the arm 20 is made rigid, and the probe 14 is
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`designed to deform in a different region, called the deflection
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`region 22, of its body 21.
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`In particular, H1 is the distance between the rigid arm 20
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`and the lower die 12B and corresponds to the maximum
`overtravel allowed to the probe 14, while H is the height of
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`Page 14 of 18
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`US 6,768,327 B2
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`5
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`the rigid arm 20 extending laterally with respect to the body
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`21 of the probe 14.
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`Advantageously, as will be shown in a greater detail in the
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`following description, the testing head 100 according to the
`embodiments of the invention allows a reduction in the
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`minimum pitch value for the contact tips 15, thus allowing
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`the testing of integrated electronic devices having contact
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`pads with contact centers C really close, i.e. a really reduced
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`pitch value.
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`By offsetting the contact tips 15 from the longitudinal axis
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`A—A of the corresponding contact probes 14 and suitably
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`orienting the probes, the contact probes 14 can be located in
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`alternatively opposed positions with respect to the contact
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`pads 16, thus increasing the area allowed for providing the
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`guide holes.
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`Therefore, the minimum pitch distance between tips of
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`adjacent probes can be reduced, as illustrated by the non-
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`limitative examples of FIGS. 4A to 4F.
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`The minimum pitch value can be further reduced by using
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`arms with different lengths, as shown schematically in FIG.
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`4B, and/or slenderizing the end portions of the arms 20, as
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`shown schematically in FIGS. 4C and 4D.
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`It should be noted that FIG. 4D shows an arrangement for
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`guide holes having a rectangular cross-section whose major
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`side is parallel to the X—X axis of the contact pads, while
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`in FIGS. 4A—4C such axes are perpendicular to each other.
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`FIG. 4E shows a miscellaneous guide holes arrangement,
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`to be used particularly when the contact pads are provided
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`along all four sides of the chip to be tested.
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`Finally, FIG. 4F shows a modified guide holes
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`arrangement,
`to be used too when the contact pads are
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`provided along all four sides of the chip to be tested.
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`In particular, the adjacent probes 14 are located in alter-
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`natively opposed positions with respect to the contact pads
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`16 and having a sloping symmetry axis with respect to the
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`alignment axis Y—Y of the contact pads 16, such axis
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`defining a predetermined angle, in a preferred embodiment
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`equal to 45°.
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`Advantageously according to an embodiment of the
`invention, the value Pitchmin of minimum pitch is given as:
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`Pitchmin=S+AIRmin
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`where S EE and, as shown schematically in FIGS. 4A to 4D:
`i.e.
`Pitchmin is the minimum pitch,
`the least distance
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`between centers of two adjacent contact pads 16 of the
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`electronic integrated device to be tested;
`S is the cross-section dimension of the tip 15 of the
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`contact probe 14;
`AIRmin is the minimum distance between two adjacent
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`arms; and
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`E is the cross-section dimension of the contact probe 14.
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`In particular, FIGS. 4C and 4D show that the value of S
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`can be made much smaller than E by suitably slenderizing
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`a part of or the entire end portion of the arm 20.
`From the above described examples, it can be noted that
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`it is especially advantageous if the contact probes 14 have
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`non-circular cross-sectional shapes. In a preferred embodi-
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`ment of the invention, a probe 14 with a rectangular cross-
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`section is provided by way of example. The corresponding
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`guide holes 13A and 13B are here to also have a rectangular
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`cross-sectional shape, so that the probes 14 passed through
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`them are always oriented for proper engagement with the
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`contact pads 16 on the electronic integrated device 17 to be
`tested.
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`Page 15 of18
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`6
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`Rectangular cross-section holes allow the probe spacing
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`to be further reduced form circular ones, resulting in a still
`smaller value for the minimum pitch, as shown in FIGS. 4A
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`to 4F.
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`In addition, the compressive deflection of a non-circular
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`cross-section probe 14 in its deflection region 22, as the
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`probe 14 is abutted against the electronic integrated device
`17 to be tested, can be controlled much better because the
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`deformation will take place in a given plane.
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`In this case, the probe orientation and precise positioning
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`of the contact tip 15 on the contact pad 16 is ensured by the
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`accurate orientation of the rectangular cross-section guide
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`hole 13A preventing the probe 14 therein from turning.
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`The deflection region between the dies can be provided by
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`any of the techniques commonly employed for vertical
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`contact testing heads. As an example, the deflection region
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`may be at least one air space between at least two dies that
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`are either aligned or offset and have their guide holes formed
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`with a straight or non-straight cross-sectional shape; in this
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`region the probes may be straight, pre-bent, or have pre-
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`deformed portions to encourage deflection upon contact.
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`FIG. 5 shows a testing head 100 comprising a plurality of
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`contact probes 14 having a rigid arm 20 with a slenderized
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`shape and a sloping symmetry axis B-B with respect to the
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`symmetry axis A—A of the body 21 of the probe 14.
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`In this Figure, H1 is the maximum overtravel allowed to
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`the probe 14, while H is the height of the rigid arm 20
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`extending laterally with respect to the body 21 of the probe
`14.
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`FIG. 6 shows by way of a non-limitative example a testing
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`head 100 comprising three dies 12A, 12B and 12B defining
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`a first 22A and a second deflection region 22B.
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`The testing head according to the embodiment of FIG. 6
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`allows to use contact probes 14 having a greater length than
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`the testing heads according to the embodiments of FIGS. 3
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`and 5,
`thus facilitating the corresponding manufacturing
`process.
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`In a more general case, it is possible to define N deflection
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`region using N+1 dies.
`In such a case, it should be noted that the N+1 dies can be
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`opportunely offset in order to facilitate and guide the deflec-
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`tion of the probes 14 in a particular direction within the
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`respective deflection regions 22.
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`As a further example, where the testing head comprises
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`loose-mounted probes, the risk of probes dropping out of the
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`dies can be minimized by increasing the frictional drag of
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`the contact probes 14 through the dies 12A and 12B.
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`For this purpose, the dies are offset a greater or lesser
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`amount, such that their corresponding sets of guide holes are
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`aligned together to a greater or lesser extent along normal
`directions to the dies.
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`It would be further possible to use dies provided with
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`straight or non-straight guide holes, or even straight or
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`pre-deformed contact probes.
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`Advantageously according to further embodiments of the
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`invention, the frictional drag of the probes 14 through the
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`guide holes 13 is obtained by rotating the guide holes of at
`least one of the dies of a suitable angle, indicated as (X in the
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`example shown in FIG. 7, with respect to the corresponding
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`guide holes provided in the other dies of the testing head.
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`Alternatively, it is possible to made guide holes having
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`slightly sloped axis in at least one of the dies, as shown in
`FIG. 8.
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`Finally, advantageously according to a further embodi-
`ment of the invention, an increased frictional drag of the
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`probes 14 through the guide holes 13 is obtained by using
`guide holes having a suitable form in at least one of the dies,
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`Page 15 of 18
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`US 6,768,327 B2
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`7
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`in order to elastically deform the contact probe, for example
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`along its cross-sectional axis, as shown in FIG. 9.
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`Alternatively, it is possible to pre-deform the body 21 of
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`the probes 14 along its cross-sectional or longitudinal axis.
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`Finally, in order to further reduce the risk of the contact
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`probes dropping out of their guide holes, an elastic film may
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`be applied to either die in any of the embodiments described
`hereinabove.
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`In conclusion,
`the testing head 100 according to the
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`embodiments of the invention has, unlike vertical-probe
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`testing heads according to the embodiments of the prior art,
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`its contact probes 14 deformed substantially lengthwise and
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`offset with their longitudinal axes from their contact points
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`on the contact pads 16, thereby combining the advantages of
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`both the vertical and horizontal technologies.
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`Changes can be made to the invention in light of the above
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`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
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`and devices that are in accordance with the claims.
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`Accordingly, the invention is not limited by the disclosure,
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`but instead its scope is to be determined by the following
`claims.
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`We claim:
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`1. A testing head having vertical probes and comprising:
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`a top and a bottom plate-like holder provided with respec-
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`tive guide holes; and
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`a contact probe structured to be received in the guide
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`holes and having a contact tip structured to establish
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`mechanical and electrical contact to a corresponding
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`contact pad of an integrated electronic device to be
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`tested, the contact probe being deformed in a deflection
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`region located between the top and bottom plate-like
`holders as the contact tip abuts onto the contact pad
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`wherein the contact probe further comprises:
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`a body having a longitudinal axis extending through the
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`bottom plate-like holder to an end portion below the
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`bottom plate-like holder; and
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`a rigid arm extending transversely from the end portion
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`of the body of the contact probe and terminating in
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`the contact tip,
`the rigid arm being structured to
`offset the contact point of the contact probe with the
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`corresponding contact pad with respect to the lon-
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`gitudinal axis of the body of the contact probe.
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`2. The testing head of claim 1, wherein the longit