`US 200702 I 0813Al
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`(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2007/0210813 A1
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` Hirakawa et al. (43) Pub. Date: Sep. 13, 2007
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`(54) PROBE FOR ELECTRICAL TEST AND
`PROBE ASSEMBLY
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`(30)
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`Foreign Application Priority Data
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`(75)
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`Inventors:
`
`Hidekl Hirakawa. Hirosaki-shi
`(JP): Akira Souma. Hirakawa-shi
`(JP): Takayukl Hayashizaki.
`Hirakawa-shi (JP); Shlnjl
`Kuniyoshi- Tokyo (JP)
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`Correspondence Address:
`INGRASSIA FISHER & LORENZ, RC.
`7150 E. CAMELBACK. STE. 325
`SCOTTSDALE. AZ 85251
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`.
`(73) ASSIEMC:
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`7
`7
`KABUSHIKI KAISH’.‘ “IRON
`MICRONICS Musashlno—shi (JP)
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`(2]) App]. No.:
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`11/627300
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`(22)
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`Filed:
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`Jan. 26. 2007
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`Mar. 7. 2006
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`(.ll’)
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`2006-6055]
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`_
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`.. ,_
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`Publication (.Iassihcatlon
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`(51)
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`Int. Cl.
`(2006.01)
`601R 31/02
`(52) US. Cl.
`....................................................... 324/754
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`ABSTRACT
`(5-7)
`A probe for electrical test comprises a probe body having a
`base end attached to a support base plate through a solder
`and a front end continuous with said base end and a surface
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`layer showing a conductivity higher than that of the probe
`body and a solder wettability higher than that of the probe
`body and extending on the surface of the probe body from
`the base end to the front end. In the vicinity of the base end
`of the surface layer. a shield region having. a smaller solder
`wettability than that of the surface layer is fonned across the
`surl'ace layer.
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`24 20b
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`[10
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`Feinmetall Exhibit 2018
`FormFactor, Inc. v. Feinmetall, GmbH
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`Sep.l3,2007
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`PROBE FOR ELECTRICAL TEST AND
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`PROBE ASSEMBLY
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`TECHNICAL FIELD
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`bond strength and becomes a bar to the stable bond strength
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`between the probes and the support base plate where the
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`probes are to be soldered.
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`BRIEF SUMMARY
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`[0001] The present invention relates to a probe and a probe
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`assembly suitable for use in an electrical test of a semicon-
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`ductor apparatus such as a semiconductor integrated circuit.
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`BACKGROUND
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`[0002]
`Semiconductor devices such as a plurality of semi-
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`conductor integrated circuits formed on each chip region of
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`a semiconductor wafer are subjected to an electrical test for
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`determining whether or not each one is produced as per
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`specification. In an electrical
`test of this type, a probe
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`assembly generally called a probe card is used. When a
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`plurality of probes (contacts) provided on a probe base plate
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`ofthis probe assembly are pressed against the corresponding
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`electrodes of a device under test, the device under test is
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`comiected to a tester for electrical test through the probe
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`assembly.
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`[0003] Among probes of a probe assembly of this type,
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`there is a blade-type one formed by using a photolithography
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`technique (Japanese Patent Appln. Public Disclosure No.
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`2004-340654). This blade-type probe includes a plate-like
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`blade body. The plate-like blade body has a mounting
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`portion on a support base plate, a rising portion which rises
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`from the mounting portion, and an arm portion extending
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`laterally from the rising portion on a plane which includes
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`this rising portion. At the front end of the arm portion of the
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`blade body, a tip projecting from the side opposing the side
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`where the mounting portion is located is formed. In order to
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`surely press the tip against an electrode of a device under
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`test, the blade body is generally made of a highly tenacious
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`(flexible) metal material such as nickel and its alloy. How-
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`ever, because of comparatively high electrical resistance,
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`such a metal material has a problem in accurate repeatability
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`of a rectangular wave signal used for an electrical test.
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`[0004] Thus, the Applicant of this Application proposed
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`earlier, as shown in FIG. 8 in Japanese Patent Application
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`2005-163546 or
`lntemational Patent Application PCT/
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`JP2005/014871, to cover the surface ofthe body 2 ofa probe
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`1 with a rolled gold layer 3 to make this rolled gold layer 3
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`function as an electrically conducting path, thereby to lower
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`the electrical resistance of the probe.
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`[0005] Compared with a metal material which forms the
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`probe body 2, the rolled gold layer 3 is superior in wetta-
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`bility relative to a solder 4 such as tin or tin alloy, and this
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`rollcd gold layer 3 covers the surface of the probe body 2.
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`Thus, when the solder 4 is used to combine the probes l with
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`a wiring path 5 provided on the support base plate of the
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`probe assembly, the wettability of the rolled gold layer 3
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`sometimes causes the solder 4 to spread farther than required
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`in a direction (upward in FIG. 8) to be away from a base end
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`combining the probe body 2 with the wiring path 5.
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`Such an excessive spread of the solder 4 due to the
`[0006]
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`wettability of the rolled gold layer 3 complicates formation
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`of an adequate fillet shape for the solder 4 to display a stable
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`[0007] An object of the present invention is, therefore. to
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`provide a probe and a probe assembly which can be surely
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`soldered onto a support base plate.
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`[0008] The present invention relates to a probe for elec-
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`trical tcst provided with: a probe body having a front end
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`continuous with a base end which is mounted on a support
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`base plate through a solder and a front end continuous with
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`the base end; a surface layer showing a conductivity higher
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`than the conductivity of the probe body and a solder wet-
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`tability higher than the wettability of the probe body, and
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`extending on the surface of the probe body from the base end
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`to the front end, and is characterized in that, in the vicinity
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`of the base end of the surface layer, a shield region is formed
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`across the surface layer, the shield region having a smaller
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`solder wettability than that of the surface layer.
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`[0009] According to the probe of the present invention, the
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`shield region formed across the surface layer prevents the
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`solder from spreading due to the wettability of the surface
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`layer excessively to be away from the base end which is a
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`connection end to the support base plate. This enables the
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`solder to retain a proper fillet shape at a soldered portion of
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`the probe to surely solder the probe onto the support base
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`plate, whereby a stable solder bond strength therebetween
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`can be obtained.
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`[0010]
`It is possible to provide in the probe body with a
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`mounting portion including the base end and a rising portion
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`extending from the mounting portion to the side opposing
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`the side where the base end is located to be continuous with
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`the tip. In this case, a spread of the solder wetting from the
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`mounting portion to the rising portion can be surely pre-
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`vented by forming the shield region in the vicinity of the
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`rising portion in the mounting portion.
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`[0011] The probe body can be formed like a flat plate such
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`that the mounting portion and the rising portion are formed
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`to be flush with each other. Along at least one face ofthis flat
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`plate-like probe body, the surface layer can be continuously
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`formed from the mounting portion to the rising portion.
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`[0012] The solder can be preformed as a solder layer on
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`the surface layer prior to mounting the probe body on the
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`support base plate closer to the base end side than to the
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`shield region in the mounting portion. As such a solder layer,
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`an adequate necessary amount without excess or shortage
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`can be previously retained in the probe, thereby enabling to
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`efficiently perform adequate soldering work of the probe.
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`[0013]
`Further, an arm portion extending laterally from the
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`rising portion can be provided in the probe body. The
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`terminal end of the arm portion defines the front end of the
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`probe body, and the front end can be provided with a tip
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`projecting longitudinally to the side opposing the side where
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`the base end is located. By providing such an arm portion in
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`the probe body, the tip can be adequately engaged with an
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`electrode of a device under test by proper flexing deforma-
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`tion accompanying the elasticity of the arm portion.
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`[0014]
`It is desirable to make the probe body of a metal
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`material superior to the tip in tenacity and make the tip of a
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`metal material superior to the probe body in hardness for
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`having the probe tip properly engaged with the electrode,
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`and for enhancing the durability of the probe.
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`Page 9 of 12
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`US 2007/0210813 A1
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`Sep.13,2007
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`[0015]
`In one example of such a combination of materials,
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`rhodium is used as the material of the tip, and nickel, its
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`alloy or phosphor bronze is used as the material of probe
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`body. It is also possible to use gold as the material of the
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`surface layer and nickel or its alloy as the material of the
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`shield region. In this case, the solder is composed of tin or
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`its alloy.
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`[0016] The surface of the shield region can be oxidized.
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`By this, the solder wettability in the shield region can be
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`further lowered, so that the function of the shield region to
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`prevent the solder from spreading can be further improved.
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`[0017] The probe assembly comprising the support base
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`plate and the probes firmly coupled with the support base
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`plate can be provided by soldering a plurality of probes
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`according to the present invention onto the support base
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`plate having a plurality of mounting lands respectively
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`corresponding to the probes.
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`[0018] According to the present invention, as mentioned
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`above, the surface layer of the probe body prevents unnec—
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`essary wetting and spread of the solder and enables the
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`solder to retain a proper fillet shape in the soldered portion,
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`thereby surely soldering the probes onto the support base
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`plate to obtain a stable solder bond strength therebetween.
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`BRIEF DESCRIPTION OF THE DRAWINGS
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`[0030] The end face 16a of the mounting portion 16 serves
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`as a base end of the probe body 12 and as a mounting face
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`on a land portion 22a formed in a wiring path 22 on the
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`support base plate 14. The rising portion 18 rises from the
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`mounting portion 16 from the opposite side to the end face
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`16a. The arm portion 20 is also continuous with the mount-
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`ing portion 16 through the rising portion 18, and its front end
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`face 20b dcfincs thc front cnd of the probe body 12.
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`According to the illustration, in the front end face 20b, a tip
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`24 projecting from the front end face is formed by another
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`mcmbcr partially cmbcddcd in thc probc body 12.
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`[0031] The probe body 12 is made of a metal material
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`having a relatively high tenacity such as, for example,
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`nickel, its alloy or phosphor bronze. In the illustration, a
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`long hole 26 penetrating in the thickness direction of the arm
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`portion 16 and extending longitudinally thereof is formed so
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`as to enhance the llexibility of the arm portion 16. As is
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`heretofore well known, the probe body 12 can be formed by
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`using a photolithography technique using selective exposure
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`of a photo resist and a development process, and a plating
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`technique such as an electroforrning to deposit a metal
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`material on a pattern formed by selective exposure and
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`development of the photo resist.
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`[0032] The tip 24 can be made of the same metal material
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`as the probe body 12 integrally with the probe body 12. To
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`improve the durability, however, it is preferable, as shown in
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`the illustration, to make the tip 24 of a pyramidal shape of
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`a metal material having a higher hardness than that of the
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`probe body 12 and bury this tip 24 within the front end
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`portion of the arm portion 20. Thus, the durability of the tip
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`can be enhanced without spoiling the flexibility of the probe
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`body 12.
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`[0033]
`In order to enhance the conductivity of the probe
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`10, as shown in FIGS. 2 and 3, a surface layer 28 showing
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`a higher conductivity than that of the probe body is formed
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`on both faces of the probe body 12. This surface layer 28 can
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`be made of gold on the probe body 12, for example, by
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`electroplating.
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`[0034] The solder 30 made of a conductive adhesive
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`material which can melt such as a simple substance of tin or
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`tin alloy shows a higher wettability to the gold constituting
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`the surface layer than to the metal material constituting the
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`probe body 12. In other words, the surface layer 28 shows
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`a high solder wettability in comparison with the probe body
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`12. As a tin alloy, an alloy of tin with either one or more of
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`gold, silver, cupper and bismuth can be named.
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`[0035] Thc surfacc laycr 28 showing a high wcttability is
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`formed, as shown in FIG. 3, to surround the periphery of the
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`mounting portion 16 of the probe body 12 and cover the
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`mounting portion. Also, as shown in FIG. 1, the surface layer
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`28 is continuously formed to cover both faces of the probe
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`body 12 in the region from the mounting portion 16 through
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`the rising portion 18 and the arm portion 20 to the front end
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`face 20b and comes into electrical contact with the tip 24 at
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`the front end face 20b. This surface layer 28 is not neces-
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`sarily directly connected to the tip 2419 on the front end face
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`20b, and it contributes to improvement in conductivity of the
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`probe 10 so long as it functions as a partial conductive
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`bypass of the probe body 12.
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`[0036] On the surface layer 28 covering the mounting
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`portion 16, a strip—like shield region 32 is formed near the
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`rising portion 18 in the mounting portion 16 so as to cross
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`the surface layer 28 extending along the rising portion 18.
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`This shield region 32 permits the surface layer 28 to expose
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`[0019]
`FIG. 1 is a front elevation showing an embodiment
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`of a probe of the present invention.
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`[0020]
`FIG. 2 is a section obtained along the line II-II in
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`FIG. 1.
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`[0021]
`FIG. 3 is a partial perspective view schematically
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`showing a connecting process of the probe of the present
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`invention to an electric wiring path.
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`FIG. 4 is a View similar to FIG. 2 showing another
`[0022]
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`embodiment of the probe of the present invention.
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`FIG. 5 is a view similar to FIG. 2 showing still
`[0023]
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`another embodiment of the probe of the present invention.
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`[0024]
`FIG. 6 is a bottom view of the probe assembly with
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`thc probcs of the present invcntion incorporatcd thcrcin.
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`[0025]
`FIG. 7 is a front elevation of the probe assembly
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`with the probes of the present
`invention incorporated
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`therein.
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`[0026]
`FIG. 8 is a view similar to FIG. 2 showing a
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`conventional probe.
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`DETAILED DESCRIPTION
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`[0027] The present invention is explained in the following
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`according to the illustrated embodiments.
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`[0028] As shown in FIG. 1, a probe 10 according to the
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`present invention is provided with a generally plate-like
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`probe body 12. The probe body 12 is provided with a
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`mounting portion 16 which is a connecting portion to a
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`support base plate 14, a rising portion 18 which rises from
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`the mounting portion in plane with the mounting portion 16,
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`and an arm portion 20 extending horizontally in the lateral
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`direction from the top of the rising portion in plane with both
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`mounting and rising portions 16 and 18. The arm portion 20
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`terminates at a front end face 201) through a curved portion
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`2011 which curves toward the side opposing the side where
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`the mounting portion 16 is located.
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`[0029]
`In the illustration, the rising portion 18 rises at right
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`angle from the mounting portion 16, but it may rise from the
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`mounting portion 16 at an angle different from 90°.
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`Page 10of12
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`Page 10 of 12
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`US 2007/0210813 A1
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`Sep.l3,2007
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`the plating layer, being capable of surer preventing the
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`solder from extruding, is effective particularly to the probes
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`arranged at narrow pitches.
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`In place of forming the shield region 32 on the
`[0042]
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`surface layer 28, it is possible, as shown in FIG. 5, to provide
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`an annular region for exposing the surface of the probe body
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`12 so as to divide the surface layer 28 and embed the shield
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`rcgion 32 in the annular rcgion. In this case, a cable run by
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`the surface layer 28 is divided by the shield region 32 which
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`is lower in conductivity than the surface layer 28, but since
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`the surface layer 28 functions as a partial conductive bypass
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`of the probe body 12 as mentioned above, the surface layer
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`28 contributes to improving the conductivity of the probe 10.
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`[0043]
`It is desirable, however, just as illustrated in FIGS.
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`1 through 4, to form a shallow annular dented groove (not
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`shown) which does not expose the surface of the probe body
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`12 in the surface layer 28 in order to surely improve the
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`conductivity by the surface layer 28 and to accommodate the
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`shield region 32 in the dented groove.
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`[0044] The above-mentioned probe 10 can be used in a
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`probe assembly 34 shown in FIGS. 6 and 7.
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`[0045] This probe assembly 34 is applied to a continuity
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`test of, for example, a semiconductor integrated circuit such
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`as plural semiconductor chips arranged in a matrix state on
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`a semiconductor wafer not shown. As shown in FIGS. 6 and
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`7, the probe assembly 34 comprises a circular wiring base
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`plate 36, and a rectangular probe base plate 38 disposed on
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`the underside of the wiring base plate. As shown in FIG. 6,
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`a plurality of tester lands 36a to be connected to a tester (not
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`shown) for electrical test are formed on the upside of the
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`wiring base plate 36.
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`[0046] The probe base plate 38 has an electrical insulation
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`plate such as, for example, ceramic not shown but well
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`known heretofore, and a plurality of wiring paths 22 are
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`formed on the underside of the insulation plate (see FIGS.
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`1-5). Each wiring path 22 is electrically connected to its
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`corresponding tester land 3611. Also, the probe 10 is adhered
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`to the probe land portion 22a formed in each wiring path 22
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`(see FIGS. 1-5).
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`tips 24 are
`[0047]
`In the example shown in FIG. 6,
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`arranged to be inserted alternately from both sides in each of
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`lines L1-Ln such that the above-mentioned plural probes 10
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`are arranged with their tips 24 aligned along the plural lines
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`Ll-Ln.
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`[0048] By the probes 10 according to the present inven-
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`tion, even in a very narrow pitch alignment to correspond to
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`the semiconductor chips, each probe can be surely soldered
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`to the land portion 22a of the corresponding wiring path 22
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`without short-circuiting at a soldcrcd portion bctwccn adja-
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`cent probes 10.
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`[0049] The present invention is not limited to the above
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`embodiments but can be variously modified without depart-
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`ing from its purport.
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`What is claimed is:
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`1. A probe for electrical test comprising:
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`a probe body having a base end attached to a support base
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`plate through a solder and having a front end continu-
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`ous with the base end; and
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`a surface layer showing a conductivity higher than that of
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`said probe body and a solder wettability higher than
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`that of said probe body, said surface layer extending
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`from said base end to said front end on the surface of
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`said probe body, wherein in the vicinity of said base
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`end of said surface layer a shield region with the solder
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`a broad area for a coupling face of the solder 30 on the side
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`of the end face 16a of the mounting portion 16 rather than
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`the side of the shield region.
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`[0037] The shield region 32 can be made of the same metal
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`material as that of the probe body 12, for example, a plating
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`layer of nickel or its alloy. Being made of the same material
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`as that of the probe body 12, the shield region 32 shows a
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`wettability lower than that of the surface layer 28. While this
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`shield region 32 lowers the wettability even by native
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`oxidation, the wettability can be further lowered rapidly, for
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`example, by heat treatment at 200° C. for three hours.
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`In order to connect the probe 10 according to the
`[0038]
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`present invention to the land portion 22a in the wiring path
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`22 ofthe support base plate 14, as shown in FIG. 3, a proper
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`amount of the solder 30 is applied to a region exposed from
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`the shield region 32 on the side of the end face 16a rather
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`than the side of the shield region 32 in a part covering the
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`peripheral plane of the mounting portion 16 of the surface
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`layer 28. The solder-applied probe 10 is secured to the land
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`portion 22a after melting the solder 30, for example, by a
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`laser beam with the end face 16a abutted on the land portion
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`22a, and by solidifying the solder 30, whereby the probe 10
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`is supported on the support base plate 14 in a cantilever state.
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`[0039]
`If the above-mentioned shield region 32 is not
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`present on the surface layer 28, as explained as a conven-
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`tional art in line with FIG. 8, the wettability of the rolled
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`gold layer 3 causes the melted solder 4 to spread largely in
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`a direction to be away from the wiring path 5. Also, due to
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`the gravity,
`this liquidized solder 4 is caused to form
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`downward droop. As mentioned above, however, due to
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`great wettability of the rolled gold layer 3,
`the solder 4
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`wetting and spreading in a broad area does not largely spread
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`out of the probe body 2 in the vicinity of the joint face
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`between the wiring path 5 and the probe 1, and the solder 4
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`while solidifying as the temperature falls does not spread
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`largely out of the probe body 2 in the vicinity of the joint
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`face between the wiring path 5 and the probe 1, but the
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`solidified solder 4 just forms a thin fillet portion.
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`[0040] On the other hand, according to the present inven-
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`tion, as shown in FIG. 2, the shield region 32 with low
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`wettability is prevented from spreading along the rising
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`portion 18 on the surface layer 28 beyond the shield region.
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`Thus, there is no spreading of the melted solder 30 to wet
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`more than necessary up to a region distant from the joint
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`portion between the land portion 22a and the end face 16a
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`of the probe body 12. Therefore,
`the solder 30 forms a
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`favorable fillet shape stretching out of the surface of the
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`probe body 12 in the vicinity of the joint portion by its
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`solidification. Thus, a favorable and stable coupling of the
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`probe 10 and the support base plate 14 can be achieved.
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`[0041]
`In place of applying the solder 30 to the probe 10
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`when coupling the probe 10 with the support base plate 14,
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`it is desirable, as shown in FIG. 4, to pre-form the solder 30
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`as a plating layer on the surface layer 28 which is exposed
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`from the shield region 32 at this mounting portion 16. This
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`plating layer 30 can be formed, for example, by a plating
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`method using the electroforrning technique. In the solder
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`layer 30, the amount of the solder to be expressed by the
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`product of its thickness and area on the surface layer 28
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`where the solder plating layer is formed can be accurately
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`controlled. Consequently, by pre-forming the solder layer 30
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`in each probe 10, an adequate amount of solder can be easily
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`supplied to each probe 10 without excess or shortage. Thus,
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`Page 11 of12
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`Page 11 of 12
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`US 2007/0210813 A1
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`Sep.l3,2007
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`rising portion, its terminal end defining said front end, and
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`wherein said front end is provided with a tip projecting
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`longitudinally to the side opposing the side where said base
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`end is located.
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`6. A probe claimed in claim 1, wherein said probe body is
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`made of a metal material superior to said tip in high tenacity,
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`and wherein said tip is made of a metal material superior to
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`said probe body in hardness.
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`7. A probe claimed in claim 5, wherein said probe body is
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`made of nickel, its alloy or phosphor bronze, said surface
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`layer is made of gold, said shield region is made of nickel
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`or its alloy, and wherein said solder is made of tin or its alloy.
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`8. A probe claimed in claim 6, wherein the surface of said
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`shield region is oxidized so as to further lower the solder
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`wettability.
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`9. A probe assembly comprising a support base plate
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`having a plurality of mounting lands, and the plural probes
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`claimed in claim 1 with their base ends attached like a
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`cantilever to the corresponding attachment lands through a
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`solder.
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`wettability smaller than that of said surface layer is
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`formed across said surface layer.
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`2. A probe claimed in claim 1, wherein said probe body
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`has a mounting portion including said base end, and a rising
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`portion extending from said mounting portion to the side
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`opposing the side where said base end is located, wherein
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`said shield region is formed in the Vicinity of said rising
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`portion in said mounting portion so as to prcvcnt said soldcr
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`from spreading to wet from said mounting portion to said
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`rising portion.
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`3. A probc claimed in claim 1, wherein said probc body is
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