JP2011202990A - Contact probe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a contact probe for suppressing the occurrence of variations in a height of the contact probe which is fixed to a wiring board using a jointing material which is made of a low melting point metal.SOLUTION: The contact probe includes: a base 3 made of a first conductive metal and having a contact region 7 allowed to be in contact with a terminal electrode 12 formed on a probe board 11; a jointing material holding region 5 for holding the jointing material 15 which is made of a low melting point metal while the contact region 7 is exposed; and a jointing material lead-in region 6 which is formed at least between the contact region 7 and the jointing material holding region 5, and in which a metal film 9 is formed that is made of a second conductive metal having wettability to a low melting point metal higher than that of the first conductive metal.

Description

  The present invention relates to a contact probe, and more particularly to an improvement of a contact probe fixed to a wiring board using a bonding material made of a low melting point metal such as solder.

  The manufacturing process of a semiconductor device includes an inspection process for inspecting the electrical characteristics of an electronic circuit formed on an inspection object such as a semiconductor wafer. This electrical property inspection is performed using a tester device that inputs a test signal to an electronic circuit to be inspected and detects the response. For connection between the tester device and the electronic circuit, a probe card including a large number of contact probes that are brought into contact with minute terminal electrodes on the electronic circuit is used.

  Generally, in a probe card, a large number of contact probes and a large number of external terminals are formed on a wiring board, and the corresponding contact probes and the external terminals are made conductive through a wiring pattern on the wiring board. The contact probe is a probe for contacting the terminal electrode of the electronic circuit, and the external terminal is an input / output terminal for connecting a tester device.

  Each contact probe includes, for example, a contact portion that is brought into contact with an inspection object, a beam portion that elastically supports the contact portion, and a base portion that is fixed to an electrode formed on the wiring board. The base portion is fixed to the electrode on the wiring board using a bonding material made of solder. The solder is previously formed on the base portion or the electrode of the wiring board, and is heated and melted, and then cooled and solidified.

  In the conventional contact probe, since solder exists between the electrode on the wiring board and the base portion of the contact probe, the contact of the contact probe depends on the molten state of the solder until the solder melts and solidifies. There was a problem that the height of the part was not constant.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a contact probe that suppresses variations in height from a wiring board. In particular, it is an object of the present invention to provide a contact probe that can suppress variation in the height of a contact probe fixed to a wiring board using a bonding material made of a low melting point metal.

  A contact probe according to a first aspect of the present invention is a contact probe made of a first conductive metal and having a contact area to be in contact with an electrode of a wiring board, wherein the low melting point metal is exposed with the contact area exposed. And a second conductive metal formed between at least the abutment region and the bonding material holding region and having higher wettability with respect to the low melting point metal than the first conductive metal. And a bonding material pull-in region in which a metal film made of is formed.

  In this contact probe, a pull-in region of a bonding material made of a low melting point metal is formed at least between the contact region and the bonding material holding region, and the wettability with respect to the low melting point metal is higher than the conductive metal constituting the contact probe. A metal film made of a conductive metal is formed in the bonding material drawing region. According to such a configuration, when the bonding material on the bonding material holding region is melted and the contact probe is fixed to the electrode on the wiring board, the molten bonding material moves on the metal film having good wettability. Accordingly, the bonding material can be guided to a position closer to the contact area, and the contact probe can be bonded to the electrode without interposing the bonding material between the contact area and the electrode on the wiring board. Accordingly, since the contact area does not have to be covered with the bonding material, sinking due to melting of the bonding material can be suppressed, and variation in the height of the contact probe from the wiring board can be suppressed. .

  In addition to the above configuration, the contact probe according to the second aspect of the present invention is configured such that the bonding material drawing region partially overlaps the bonding material holding region. According to such a configuration, since the bonding material is held by being overlapped with the metal film having good wettability, the molten bonding material can be easily guided to a position closer to the contact area.

  According to the contact probe of the present invention, when the molten bonding material moves on the metal film having good wettability, the bonding material can be guided to a position closer to the contact area, and the contact area and the wiring board The contact probe can be bonded to the electrode without interposing a bonding material with the upper electrode. Accordingly, since the contact area does not have to be covered with the bonding material, sinking due to melting of the bonding material can be suppressed, and variation in the height of the contact probe from the wiring board can be suppressed. .

It is the top view which showed an example of schematic structure of the probe card 100 by embodiment of this invention. FIG. 2 is a perspective view illustrating a configuration example of a main part of the probe card 100 of FIG. 1, in which a contact probe 10 fixed to a terminal electrode 12 on a probe substrate 11 is illustrated. FIG. 3 is a cross-sectional view showing a configuration example of the contact probe 10 of FIG. 2 in comparison with a conventional one, and shows the contact probe 10 on which a bonding material 15 is formed. FIG. 2 is a diagram illustrating a configuration example of a main part of the probe card 100 of FIG. 1, in which a contact probe 10 is shown that is bonded to a terminal electrode 12 by melting a bonding material 15. It is explanatory drawing which showed typically an example of the manufacturing method of the probe card 100 of FIG. 1, and the process of forming the 1st metal layer 53 on the base is shown. FIG. 2 is an explanatory view schematically showing an example of a method for manufacturing the probe card 100 of FIG. 1, in which a process of forming the contact portion 1 on the metal layer 53 and the sacrificial layer 54 is shown. It is explanatory drawing which showed typically an example of the manufacturing method of the probe card 100 of FIG. 1, and the process of forming the 2nd and 3rd metal layers 57 and 58 is shown. FIG. 2 is an explanatory view schematically showing an example of a method for manufacturing the probe card 100 of FIG. 1, and shows a step of forming a solder plating layer 62 after forming the metal film 60. FIG. 9 is a diagram showing another configuration example of the contact probe 10 in FIG. 2, in which a metal film 9 is formed only between the bonding material holding region 5 and the contact region 7.

<Probe card>
FIGS. 1A and 1B are plan views showing an example of a schematic configuration of a probe card 100 according to an embodiment of the present invention. FIG. 1A shows a state of the probe card 100 viewed from the lower side, and FIG. 1B shows a state of the probe card 100 viewed from the horizontal direction. The probe card 100 includes a plurality of contact probes 10, a probe substrate 11, an ST substrate 20, and a main substrate 30.

  The main board 30 is a circular PCB (printed circuit board) that is detachably attached to a probe device (not shown), and a large number of external terminals 31 are provided at the periphery. The external terminal 31 is a terminal electrode for inputting / outputting a signal to / from a tester device (not shown).

  Each contact probe 10 is a probe that is brought into contact with an inspection object, and is aligned and arranged in association with the arrangement of minute electrodes of an electronic circuit to be inspected. The probe substrate 11 is a wiring substrate in which each contact probe 10 is disposed on one main surface, and is fixed to the ST substrate 20 with the other main surface facing the ST substrate 20.

  The ST substrate 20 is a wiring substrate for increasing the wiring pitch between the probe substrate 11 and the main substrate 30 or adjusting the height of the contact probe 10 from the main substrate 30. The ST substrate 20 is fixed to the main substrate 30 with the main surface opposite to the side on which the probe substrate 11 is fixed facing the main substrate 30. Further, the ST substrate 20 has a rectangular shape smaller than the main substrate 30 and is disposed at the center of the main substrate 30.

  The probe card 100 is held horizontally by the probe device with the contact probe 10 side down, and the tester device is connected. In this state, when the inspection substrate is brought closer from below and the contact probe 10 is brought into contact with the terminal electrode of the electronic circuit, the test signal can be input / output between the tester device and the electronic circuit via the contact probe 10.

<Contact probe>
FIG. 2 is a perspective view illustrating a configuration example of a main part of the probe card 100 of FIG. 1, in which the contact probe 10 fixed to the terminal electrode 12 on the probe substrate 11 is illustrated. The contact probe 10 is a cantilever (cantilever) type probe including a contact portion 1, a beam portion 2 and a base portion 3.

  The contact portion 1 is an abutting portion that abuts on the inspection object, and is formed at one end of the beam portion 2. The beam portion 2 is an elastically deformable portion that elastically supports the contact portion 1 and can be elastically deformed by a stress at the time of contact between the contact portion 1 and the inspection object. The base portion 3 is a fixing portion that is fixed to the terminal electrode 12 on the probe substrate 11 using a bonding material made of a low melting point metal such as solder, and is connected to the beam portion 2.

  The terminal electrode 12 is a flat electrode pad extending along the probe substrate 11 and is made of a conductive metal such as gold. The terminal electrode 12 is formed for each contact probe 10 and is wire-bonded to, for example, a terminal electrode formed on the ST substrate 20.

  The base portion 3 includes a thin flat plate-like bonding material holding portion 3 a and a protruding portion 3 b which is formed so as to protrude from the end surface of the bonding material holding portion 3 a and is brought into contact with the terminal electrode 12. The bonding material holding unit 3a holds a bonding material that can be easily melted by heating. The bonding material holding portion 3 a is disposed with the end surface opposite to the beam portion 2 side facing the probe substrate 11 so that the thickness direction is parallel to the probe substrate 11.

  A bonding material accommodation hole 4 for accommodating the bonding material is formed in the bonding material holding portion 3a. The bonding material accommodation hole 4 is a through hole that penetrates the bonding material holding portion 3a in the thickness direction. In this example, four protrusions 3b having the same height from the end surface of the bonding material holding portion 3a are formed. Each protrusion 3b is a columnar body having a rectangular cross-sectional shape, and is arranged in the longitudinal direction of the bonding material holding portion 3a. Further, two bonding material accommodation holes 4 are formed in the bonding material holding portion 3a, and each bonding material accommodation hole 4 has a cross-sectional shape that is long in the longitudinal direction of the bonding material holding portion 3a, that is, in the arrangement direction of the protruding portions 3b. Consists of.

  The beam portion 2 and the base portion 3 are made of a predetermined conductive metal, for example, an alloy of nickel (Ni) and cobalt (Co). On the other hand, the contact portion 1 is made of a conductive metal harder than the conductive metals constituting the beam portion 2 and the base portion 3, for example, an alloy of palladium (Pd) and cobalt.

  The bonding material used to fix the base portion 3 to the terminal electrode 12 is at least a conductive metal having a melting point lower than that of the base portion 3 or the terminal electrode 12, for example, an alloy of tin (Sn) and silver (Ag) or It consists of an alloy of tin and lead (Pb). On the base part 3, a bonding material holding region 5 for holding such a bonding material is formed.

  Since the alloy of nickel and cobalt constituting the base portion 3 does not have good wettability with respect to the solder, when the base portion 3 is fixed to the terminal electrode 12, the molten solder becomes a ball and crawls up the base portion 3. Can be considered. Therefore, a metal film having good wettability with respect to solder is formed on the base portion 3. Here, the wettability with respect to the solder is a physical quantity indicating the ease with which the molten solder becomes familiar, and when the molten solder is in contact with the metal solid, the contact angle between the molten solder (liquid) and the surface of the metal solid. Represented by the size of.

<Comparison with conventional example>
FIGS. 3A and 3B are cross-sectional views showing a configuration example of the contact probe 10 of FIG. 2 in comparison with the conventional one, and the contact probe 10 on which the bonding material 15 is formed is shown. . FIG. 3 (a) shows a contact probe 10 according to the present invention, and FIG. 3 (b) shows a conventional contact probe as a comparative example.

  In the case of a conventional contact probe, a bonding material 15 made of a sufficient amount of solder is formed on the base 3 so as to cover the abutting surface 7a of the projection 3b abutted against the terminal electrode 12 on the probe substrate 11. . The bonding material 15 is made of solder having a melting point lower than that of the metal constituting the base portion 3 and the terminal electrode 12, and is melted when the base portion 3 is fixed to the terminal electrode 12.

  In this example, the contact probe has a laminated structure of metal layers 41 to 43, and the protruding portion 3b is formed by protruding a part of the metal layer 42 from the cut surface 8a of the metal layers 41 to 43. The protrusion 3b has an abutting surface 7a that is abutted against the terminal electrode 12 and a side surface 7b that is adjacent to the abutting surface 7a. When the base portion 3 is fixed, almost the entire abutting surface 7a is a terminal. It contacts the electrode 12. On the other hand, the bonding material holding portion 3a has a cut surface 8a of the metal layers 41 to 43 as an end surface, and has a side surface 8b adjacent to the end surface. The bonding material 15 is formed so as to cover the entire abutting surface 7a, side surface 7b, and cut surface 8a, and a part of the side surface 8b.

  Therefore, when the base portion 3 of the contact probe is fixed to the terminal electrode 12, the bonding material 15 is melted in a state where the bonding material 15 remains between the abutting surface 7a of the protrusion 3b and the terminal electrode 12. As a result, the base portion 3 was submerged.

  On the other hand, in the contact probe 10 according to the present invention, the bonding material holding region 5 for holding the bonding material 15 in a state where the contact region 7 to be in contact with the terminal electrode 12 is exposed, and the metal having good wettability with respect to solder. A bonding material drawing region 6 on which the film 9 is formed is formed on the base portion 3. In this example, the abutting surface 7 a is the contact area 7.

  The bonding material holding area 5 is an area on the base portion 3 for holding the bonding material 15 in a state where the contact area 7 is exposed from the bonding material 15. In this example, the bonding material holding region 5 is formed so as to overlap a part of the side surface 7b of the protrusion 3b, a part of the cut surface 8a of the bonding material holding part 3a, and a part of the side surface 8b. .

  The metal film 9 is made of a conductive metal, such as gold (Au), that has higher wettability with respect to solder than an alloy of nickel and cobalt constituting the base portion 3. The bonding material 15 is made of solder having a melting point lower than that of the metal constituting the base portion 3 and the metal film 9. The metal film 9 is formed from the abutting surface 7a to the side surface 8b via the side surface 7b and the cut surface 8a. Specifically, the abutting surface 7a, the side surface 7b, the entire cut surface 8a, and a part of the side surface 8b are covered with the metal film 9. The metal film 9 is formed so that a part thereof overlaps the bonding material holding region 5.

  The bonding material drawing area 6 is formed on at least the base portion 3 formed between the bonding material holding area 5 and the contact area 7 in order to draw the molten bonding material 15 and guide it to a position closer to the contact area 7. The metal film 9 is formed. A part of the bonding material drawing area 6 overlaps with the bonding material holding area 5.

  When the base portion 3 is fixed to the terminal electrode 12, first, the contact region 7 is brought into contact with the terminal electrode 12 by contacting the contact surface 7 a of the projection 3 b. Then, the bonding material 15 is melted by heating in a state where the bonding material 15 does not exist between the contact region 7 and the terminal electrode 12. At this time, the molten bonding material 15 is guided to a position closer to the contact area 7 by moving on the metal film 9 having good wettability, so that the contact area 7 is not covered with the bonding material 15. In addition, it is possible to prevent poor adhesion due to scooping. For this reason, since the base part 3 can be joined to the terminal electrode 12 without interposing the joining material 15 between the contact region 7 and the terminal electrode 12, the sinking of the base part 3 due to melting of the joining material is prevented. Does not occur.

  FIG. 4 is a diagram illustrating a configuration example of a main part of the probe card 100 of FIG. 1, in which the contact probe 10 in which the bonding material 15 is melted and fixed to the terminal electrode 12 is illustrated. When the base portion 3 is fixed to the terminal electrode 12, heating is performed in a state where the contact region 7 of each protrusion 3 b is in contact with the terminal electrode 12.

  For example, by irradiating a part of the base part 3 with laser light, the vicinity of the irradiation point is locally heated and the bonding material 15 is melted. At this time, since the familiar metal film 9 is formed on the base portion 3, the molten bonding material 15 moves on the metal film 9 and is guided to a position closer to the contact region 7 of the protrusion 3b. Is done. Therefore, the molten bonding material 15 does not scoop up the base portion 3 as a ball, and a good solder fillet is formed.

<Manufacturing process>
FIGS. 5 to 8 are explanatory views schematically showing an example of a method for manufacturing the probe card 100 of FIG. 1, showing a process of forming a contact probe 10 by laminating a conductive metal layer on a pedestal. Has been.

  5A to 5C show a process of forming the first metal layer 53 on a pedestal on which a conductive film 51 is previously formed on the substrate 50. FIG. The conductive film 51 is a base film for forming the conductive layer 53 by electroplating, and is made of, for example, copper (Cu).

  In FIG. 5A, a photoresist is applied on the conductive film 51 to form a resist layer 52, and the resist layer 52 is patterned in order to form a metal layer 53 constituting the beam part 2 and the base part 3. The process to do is shown.

  FIG. 5B shows a process of forming a metal layer 53 on the substrate 50 after patterning the resist layer 52 by electroplating. The metal layer 53 is formed on the conductive film 51 as a nickel-cobalt plating layer. FIG. 5C shows a process of removing the resist layer 52 from the substrate 50 after the metal layer 53 is formed.

  6A to 6C show a process of forming the metal layer 56 constituting the contact portion 1 on the metal layer 53 and the sacrificial layer 54. FIG. 6A shows a step of forming a sacrificial layer 54 for forming the metal layer 56 and the protruding portion 3b on the substrate 50 after the resist layer 52 is removed. The sacrificial layer 54 is formed on the conductive film 51 by applying and patterning a photoresist and electroplating copper.

  In FIG. 6B, a photoresist is applied to the substrate 50 after the sacrificial layer 54 is formed to form a resist layer 55, and the resist layer 55 is patterned to form a metal layer 56 by electroplating. The process is shown. The metal layer 56 is formed as a palladium-cobalt plating layer. FIG. 6C shows a process of removing the resist layer 55 from the substrate 50 after the metal layer 56 is formed.

  7A to 7C show a process of forming the second and third metal layers 57 and 58 on the substrate 50 after the resist layer 55 is removed. FIG. 7A shows a step of forming the metal layer 57, and FIG. 7B shows a step of forming the metal layer 58.

  The metal layer 57 is formed on the metal layer 53 and the sacrificial layer 54 as a nickel-cobalt plating layer. The metal layer 58 is formed on the metal layer 57 as a nickel-cobalt plating layer. FIG. 7C shows a process of removing a part of the sacrificial layer 54 and the conductive film 51 from the substrate 50 after the metal layers 57 and 58 are formed.

  8A to 8C show a process of forming a solder plating layer 62 after the metal film 60 is formed. In FIG. 8A, a photoresist is applied to the substrate 50 after the sacrificial layer 54 and the conductive film 51 are partially removed to form a resist layer 59, and the resist layer 59 is patterned to form a metal film. The process of forming 60 is shown.

  The metal film 60 is formed on the exposed surfaces of the metal layers 53, 57, and 58 by gold electroplating. FIG. 8B shows a process of forming a resist layer 61 by applying a photoresist to the substrate 50 after the metal film 60 is formed, and patterning the resist layer 61 to form a plating layer 62. Has been.

  The plated layer 62 is formed by bonding the exposed surfaces of the metal layers 53, 57, and 58 and the metal film 60 to the bonding material holding region 5 by electroplating an alloy of tin and silver or an alloy of tin and lead. It is formed on the material holding area 5. FIG. 8C shows a process of removing the resist layer 61 and the conductive film 51 from the substrate 50 after the plating layer 62 is formed.

  If the resist layer 61 and the conductive film 51 are removed after the plating layer 62 is formed, the contact probe 10 is completed. Of the inner wall surface of the bonding material accommodation hole 4 formed in the bonding material holding portion 3a, only the wall surface on the protruding portion 3b side is covered with a metal film 9 made of a gold plating layer. Further, the inside of the bonding material accommodation hole 4 is filled with a bonding material 15 made of a solder plating layer 62.

  According to the present embodiment, the bonding material 15 is formed between the contact area 7 and the bonding material holding area 5 by forming the bonding material drawing area 6 in which the metal film 9 having good wettability with respect to the solder is formed. When the base part 3 is fixed to the terminal electrode 12 on the probe substrate 11 by melting the base material 3, the melted bonding material 15 can be guided to a position closer to the contact region 7. Therefore, it is not necessary to cover the contact region 7 with the bonding material 15 in order to prevent the molten bonding material 15 from creeping up, and the base portion 3 can be provided without the bonding material 15 being interposed between the contact region 7 and the terminal electrode 12. Can be bonded to the terminal electrode 12, so that the sinking of the base portion 3 due to melting of the bonding material 15 can be suppressed, and variations in the height of the contact probe 10 can be suppressed.

  In addition, since a part of the bonding material drawing area 6 overlaps with the bonding material holding area 5 and the metal film 9 is formed on the bonding material drawing area 6, the bonding material holding area 5 and the bonding material drawing area 6 are formed. Compared to the case where the two are separated from each other, the molten bonding material 15 can be easily guided to a position closer to the contact region 7.

  In the present embodiment, an example in which a part of the bonding material drawing area 6 overlaps the bonding material holding area 5 has been described, but the present invention is not limited to this. For example, the present invention includes a case where the bonding material drawing region 6 does not overlap the bonding material holding region 5 as long as the bonding material holding region 5 is formed on the contact region 7 side. The metal film 9 only needs to be formed on at least such a bonding material drawing region 6. In particular, in order to reduce the influence of the thickness variation of the metal film 9 on the height variation of the contact portion 1 from the probe substrate 11, it is desirable that the metal film 9 is not formed on the contact region 7.

  FIG. 9 is a diagram showing another configuration example of the contact probe 10 of FIG. 2, and the metal film 9 is only in the exposed region 72 between the bonding material holding region 5 and the contact region 7 on the base portion 3. The case of forming is shown. In the contact probe 10, the bonding material holding region 5, the bonding material drawing region 6, and the contact region 7 are formed on the base portion 3 having the abutting surface 71.

  The bonding material holding region 5 is formed at a position separated from the contact region 7 on the base portion 3. In this example, almost the entire abutting surface 71 is the contact area 7. The bonding material drawing area 6 is formed in an exposed area 72 between the bonding material holding area 5 and the contact area 7. The metal film 9 is formed only on the bonding material drawing region 6 and is not formed on the contact region 7. That is, the entire contact area 7 of the base portion 3 is exposed from the bonding material 15 and the metal film 9. With such a configuration, it is possible to prevent variations in the thickness of the metal film 9 and variations in the height of the contact portion 1 due to nonuniformity without controlling the thickness of the metal film 9 with high accuracy. it can.

DESCRIPTION OF SYMBOLS 1 Contact part 2 Beam part 3 Base part 3a Bonding material holding | maintenance part 3b Protrusion part 4 Bonding material accommodation hole 5 Bonding material holding | maintenance area | region 6 Bonding material drawing-in area | region 7 Contact area 7a DESCRIPTION OF SYMBOLS 10 Contact probe 11 Probe board 12 Terminal electrode 15 Bonding material 20 ST board 30 Main board 31 External terminals 41-43 Metal layer 71 Abutting surface 72 Exposed area 100 Probe card

Claims (2)

In the contact probe made of the first conductive metal and having a contact region that contacts the electrode of the wiring board,
A bonding material holding region for holding a bonding material made of a low melting point metal in a state where the contact region is exposed;
A bonding material drawing region formed between at least the contact region and the bonding material holding region, wherein a metal film made of a second conductive metal having higher wettability with respect to the low melting point metal than the first conductive metal is formed; A contact probe comprising:   The contact probe according to claim 1, wherein a part of the bonding material drawing area overlaps with the bonding material holding area.

Images