JP4791865B2 - Multilayer probe pins and probe cards - Google Patents

Description

  The present invention relates to a multilayer probe pin and a probe card. More specifically, the present invention relates to a multilayer probe pin that can be soldered easily, quickly, and reliably even with lead-free solder, and a probe card using the same.

  2. Description of the Related Art Conventionally, a probe card (probe pin holder) in which a plurality of probe pins are arranged is used when inspecting electrical characteristics of a semiconductor integrated circuit or a liquid crystal display device formed on a substrate. . This inspection is usually performed by bringing a probe pin into contact with each of a plurality of terminals such as a semiconductor integrated circuit element and a liquid crystal display device which are inspection objects formed on a substrate.

  In order to obtain a highly reliable test result, such a probe pin is required to stably obtain a similar test result for a long period of time even when used repeatedly. Furthermore, in order to cope with the narrowing of the pitch of terminals due to high integration of semiconductor devices and the like in recent years, it is required to narrow the probe pins and to narrow the installation interval (pin pitch) of each probe pin.

Probe pins require good electrical conductivity at the end to be in contact with the object to be inspected, while electrical insulation is required between the probe card and other adjacent probe pins. A central member made of metal is exposed at a contact portion with an object, and a multilayer probe pin having an insulating coating formed at other portions is widely used. In such a multilayer probe pin, in order to fix the probe pin and the probe card by soldering, a conductive metal layer is formed on the outer peripheral surface of the insulating layer. For example, JP2003-80364A (Patent Document 1).
JP 2003-80364 A

  Recently, due to environmental problems, solder that supports lead-free soldering has been used for the soldering that fixes the probe pin and probe card. Compared to conventional eutectic solder, such lead-free solder is used. Since the solder wettability is not good, the bonding strength is not sufficient, and a preliminary soldering process or the like may be required, so that the soldering operation cannot be performed efficiently. Further improvement of solder joint strength and efficiency of soldering work are becoming more and more important in order to cope with finer probe pins and narrower pin pitches.

  The present invention provides a multi-layer type probe pin corresponding to lead-free, which improves solder wettability and solder joint strength in a multi-layer type probe pin, and can shorten the lead time in a preliminary soldering process and a soldering process. It is.

  Therefore, the multilayer probe pin according to the present invention is a probe pin in which a central member, an insulating layer covering the central member, and a conductive metal layer formed on the outer peripheral surface of the insulating layer are combined. The surface roughness of the conductive metal layer is Ra 30 μm or less, and a conductive thin film layer is formed on at least a part of the surface of the conductive metal layer.

  Such a multilayer probe pin according to the present invention includes, as a preferred embodiment, one in which the conductive thin film layer is formed at a joint portion when the multilayer probe pin is joined to a probe card. .

  In such a multilayer probe pin according to the present invention, as a preferred embodiment, the central member is mainly composed of at least one of W, Mo, Re, Ta, Nb, Au, Ag, Pt, Ni, Co, and Cu. And those made of metal materials.

  In such a multilayer probe pin according to the present invention, as a preferred embodiment, the conductive thin film layer is made of a metal material whose main component is at least one of Sn, Au, Ag, Pt, Ni, and Cu. Is included. The conductive thin film layer is preferably a plating film.

  Such a multilayer probe pin according to the present invention includes, as a preferred embodiment, one in which the insulating layer and the conductive metal layer are joined by caulking, epoxy welding, fraying or brazing. To do.

  Such a multilayer probe pin according to the present invention includes, as a preferred embodiment, one in which the thickness of the conductive thin film layer is 0.1 μm or more and 50 μm or less.

  The probe card according to the present invention is one in which any one of the multilayer probe pins is joined by lead-free solder.

  A multilayer probe pin according to the present invention is a probe pin formed by combining a central member, an insulating layer covering the central member, and a conductive metal layer formed on the outer peripheral surface of the insulating layer, Since the surface roughness of the conductive metal layer is Ra 30 μm or less and the conductive thin film layer is formed on at least a part of the surface of the conductive metal layer, the wettability of lead-free solder is improved. It is.

  Therefore, according to the present invention, even when lead-free solder is used for joining the probe pin to the probe card, sufficient solder joint strength can be obtained and soldering work can be performed efficiently and reliably. Can do.

<Multilayer probe pin>
A multilayer probe pin according to the present invention is a probe pin formed by combining a central member, an insulating layer covering the central member, and a conductive metal layer formed on the outer peripheral surface of the insulating layer, The surface roughness of the conductive metal layer is Ra 30 μm or less, and a conductive thin film layer is formed on at least a part of the surface of the conductive metal layer.

  FIG. 1 is a sectional view showing an outline of a preferred embodiment of a multilayer probe pin according to the present invention.

  A multilayer probe pin 1 according to the present invention shown in FIG. 1 includes a central member 2, an insulating layer 3 covering the central member 2, and a conductive metal layer 4 formed on the outer peripheral surface of the insulating layer 3. A probe pin that is combined, wherein the surface roughness of the conductive metal layer 3 is Ra 30 μm or less, and the conductive thin film layer 5 is formed on at least a part of the surface of the conductive metal layer 3. It is what.

  Since the tip 2a of the central member 2 is a part that comes into contact with the inspection object when the inspection object is electrically inspected, the insulating layer 3 is at least part of the central member 2 that comes into contact with the inspection object. The central member 2 needs to be exposed without being covered.

  The center member 2 is preferably made of a metal material containing at least one of W, Mo, Re, Ta, Nb, Au, Ag, Pt, Ni, Co, and Cu as a main component. In particular, a high melting point metal such as a metal material containing at least one of W, Mo, Re, Ta, and Nb as a component, and preferably 50% by weight or more is preferable. Here, the “main component” means a component having the highest abundance ratio (weight ratio) among the metal materials constituting the central member 2. The central member 2 may contain components other than those described above, for example, Si, C, O, and the like.

  The thickness, length, cross-sectional shape of the central member 2, the shape of the tip 2a, the length of the exposed portion of the tip 2a, the exposed area, etc. are, for example, the form, size, inspection object, and specific use of the probe pin It can be appropriately determined according to conditions, manufacturing conditions, other conditions, and the like. The center member 2 of the preferred multilayer probe pin according to the present invention is as follows if its thickness, length, etc. are shown.

Thickness = Φ0.4 mm or less and length = 50 mm or less. In addition, the thickness of the tip 2a of the central portion 2 used as a detector is a guideline of φ0.2 mm or less and a length of 20 mm or less.

  An insulating layer 3 is coated on a portion of the central member 2 where electrical contact is not required at the time of inspection, for example, the surface of the central member 2 other than the tip 2a. Note that the insulating layer 3 may be formed only in a portion where insulation is required, for example, a joint portion with the probe card substrate 6. The insulating layer 3 of the present invention is preferably formed using a highly insulating resin such as an epoxy resin, a fluorine resin such as Teflon, or a silicone resin. Among these, Teflon tetrafluoride resin is particularly preferable.

  The thickness and formation position of the insulating layer 3 are arbitrary. For example, depending on the form and size of the probe pin, the shape and size of the probe card to which the probe pin is joined, the assembly method, the purpose of use, the use conditions, etc. Can be determined as appropriate. In particular, the thickness of the insulating layer 3 is suitably from 1 μm to 30 μm. If it is less than 1 μm, the coating layer may be damaged due to bending of the probe pin or contact with another probe pin, and insulation may not be maintained. On the other hand, if it exceeds 30 μm, the probe pin device with a narrow pitch There is a concern that the contact accuracy with the object to be inspected may decrease due to a decrease in flexibility and an increase in weight of the probe pin.

  Usually, the tip 2a of the probe pin may be gradually worn, altered, or contaminated by repeated use for inspection. However, the tip 2a is polished to adjust the tip shape and surface properties, or to remove the altered or contaminated part. When processing is performed, the covering portions of the central member 2 and the insulating layer 3 can be determined in consideration of the processing.

  A conductive metal layer 4 is formed on the outer peripheral surface of the insulating layer 3 of the multilayer probe pin 1 according to the present invention. The purpose of forming the conductive metal layer 4 is mainly to enable the multilayer probe pin 1 and the probe card substrate 6 to be fixed by soldering. Therefore, the conductive metal layer 4 is at least soldered. The part needs to be formed.

  The conductive metal layer 4 is preferably made of a metal material containing at least one of Cu, Ni, Cr, Co, Au, Ag, Pt, and Pd as a main component. In particular, those made of a metal material mainly containing at least one kind of Cu are preferable. Here, the “main component” means a component having the highest abundance ratio (weight ratio) among the metal materials constituting the conductive metal layer 4.

  The layer thickness of the conductive metal layer 4 is preferably 10 μm or more and 100 μm or less. The joining method of the insulating layer 3 and the conductive metal layer 4 is arbitrary, and those conventionally used in multilayer probe pins can be employed in the present invention. The insulating layer 3 and the conductive metal layer 4 can be preferably joined together by caulking, epoxy welding, fraying, or brazing.

  In the multilayer probe pin 1 according to the present invention, the conductive thin film layer 5 is formed on at least a part of the surface of the conductive metal layer 4. The conductive thin film layer 5 needs to be formed at least in a part to be joined by lead-free solder when the multilayer probe pin 1 according to the present invention and the probe card substrate 6 are joined. is there. Note that the conductive thin film layer 5 may or may not be formed in a portion that is not bonded to the probe card substrate 6 or a portion that is bonded by a method other than lead-free soldering. Here, it is important that the surface of the conductive metal layer 4 has a surface roughness Ra of 30 μm or less for at least a portion where the conductive thin film layer 5 is formed. The surface roughness Ra here is defined by JIS-B-0601. Ra is preferably 0.1 μm or more and 30 μm or less, and particularly preferably 0.5 μm or more and 3 μm or less.

  As a method for bringing the surface roughness Ra of the conductive metal layer 4 within the above range, a polishing method using Emily paper is particularly preferable. Polishing can also be employed.

  The conductive thin film layer 5 is preferably made of a metal material containing at least one of Sn, Au, Ag, Pt, Ni, and Cu as a main component. Here, the “main component” means a component having the highest abundance ratio among the metal materials constituting the conductive thin film layer 5. The conductive thin film layer 5 may contain components other than those described above, for example, Si, C, O, and the like.

  The layer thickness of the conductive thin film layer 5 is preferably 0.1 μm or more and 500 μm or less, and particularly preferably 1 μm or more and 20 μm or less. When the thickness of the conductive thin film layer is less than 0.1 μm, the adhesion at the interface is weak, whereas when it exceeds 500 μm, it is difficult to assemble, which is not preferable.

  As a method for forming the conductive thin film layer 5, any method can be used as long as the layer made of the above metal can be efficiently formed with the above thickness. Preferable methods include plating method, sol-gel, mechanical fitting method and the like.

  The multilayer probe pin 1 according to the present invention may be linear or may be bent or curved at one or a plurality of locations of the probe pin. In the present invention, it is particularly preferable to be bent and bent or curved as shown in FIG. By such processing, the multi-layer type probe pin can be made springy.

  By providing springiness in this way, when assembled into a probe card and used for inspection, wear at the tip of the probe pin is reduced and impact at the time of probe pin contact is reduced, and durability is improved. The contact state between the probe pin and the inspection object can be stabilized. The bending angle or degree of bending of the probe pin is, for example, the length and thickness of the probe pin, the shape of the tip, the contact angle with the inspection object, the position of the probe pin, and the size of the inspection object. It can be determined according to the shape, the terminal position, the pitch, and the like. Such a bent or curved probe pin is deflected upon contact with the object to be inspected, and particularly in the case of a narrow pitch probe card, the probe pin and other probe pins in the vicinity interfere with each other. Sometimes. In the multilayer probe pin according to the present invention in which the insulating layer is formed, the electrical insulation between the probe pins is well maintained even when the probe pins interfere and come into contact with each other.

  The multilayer probe pin according to the present invention is a probe pin formed by combining a central member, an insulating layer covering the central member, and a conductive metal layer formed on the outer peripheral surface of the insulating layer. Since the surface roughness of the conductive metal layer is Ra 30 μm or less, and the conductive thin film layer is formed on at least a part of the surface of the conductive metal layer, wetting with respect to lead-free solder Therefore, the multi-layer probe pin can be joined efficiently and with sufficient strength using lead-free solder.

  Specific examples of the lead-free solder in which the effects of the present invention are particularly noticeable are exemplified by lead-free solders such as Sn-Cu, Sn-Ag, and Sn-Ag-Bi. it can.

<Probe card>
The probe card according to the present invention is formed by joining the multilayer probe pins with lead-free solder.

  2 and 3 show an outline of a preferred embodiment of the probe card according to the present invention.

  FIG. 2 shows a probe card 7 having a plurality of multilayer probe pins 1 according to the present invention. In this probe card 7, each multilayer probe pin 1 has a tip portion processed into an acute angle and an insulating layer 3 on its body portion, and the body portion is bent by bending. These are bonded to the substrate 6 of the probe card by lead-free solder. The length, bending angle (bending magnitude), and bending direction (bending direction) of each multilayer probe pin may be the same or different, and the terminal 13 of the inspection object 12 with which it contacts. (Corresponding relationship between the inspection object 8 and the terminal 9 is indicated by an arrow in FIG. 2) or the like. For example, in the case of a probe card in which multilayer probe pins are arranged in parallel and multilayer probe pins are arranged at a narrow pitch (that is, the distance between the probe pins is short), interference (contact) between the probe pins is caused. It is preferable to make the bending direction the same so as to be avoided.

  The contact between the multilayer probe pin 1 and the terminal 9 according to the present invention normally maintains the parallel state between the probe card 7 on which the multilayer probe pin 1 is installed and the inspection object 8 having the terminal 9. Keep approaching as you go. By contact between the tip of each multilayer probe pin 1 and each terminal 9, the tip of the multilayer probe pin 1 and the terminal 9 are electrically connected, and the multilayer probe pin 1 bends and probe pin. The tip of the probe pin 1 is pressed against the terminal 9 by the spring characteristic of 1.

  FIG. 3 is a perspective view showing an outline of one specific example of the probe card 11 suitable for the inspection of the inspection object 10 formed on the wafer. In the probe card 11 according to the present invention of FIG. 3, the multilayer probe pin 1 is arranged in parallel to the edge of the through hole 12.

  The probe card 11 shown in FIG. 3 simultaneously inspects one row of integrated circuits among many integrated circuits formed on a wafer. Specifically, the probe card 11 is first inspected at the same time by contacting probe pins with respective terminals of a plurality of integrated circuits in a row on the wafer, and then placed the probe card 11 sideways. By shifting and repeating the process consisting of inspecting the adjacent row of integrated circuits that have been inspected first, all the integrated circuits on the wafer are inspected efficiently.

  Hereinafter, specific examples of the present invention will be described.

<Example 1>
A multilayer probe pin for solving the improvement in wettability against lead-free was prepared as follows.

First, 3% Re-W was used for a central member made of a refractory metal. The wire diameter is 0.15 mm and the length is 50.8 mm. Next, an insulating coating layer made of Teflon tetrafluoride resin was formed on the central member by covering the central member with a Teflon pipe shape having a diameter of 0.2 mm. The thickness of this insulating layer was 0.2 mm in the diameter direction. Here, when the insulation resistance of the insulating layer was measured, it was 1 × 10 ¹² Ω.

  Then, a conductive metal layer having a thickness of 0.4 mm was provided on the outer periphery of the insulating layer using brass, and the central member, the insulating coating layer, and the conductive metal layer were joined by epoxy welding. Thereafter, the brass surface was polished with emery paper # 800. The surface roughness of the conductive metal layer was Ra = 10 μm.

  Next, Sn electrolytic plating was performed on this surface. The film thickness is 3 μm in the diameter direction.

  As described above, a multilayer probe pin according to the present invention was prepared, and the wettability with a Sn-Cu-based lead-free solder and the solder joint strength were evaluated by the following methods.

  Solder wettability: “A” indicates that the solder spreading speed is fast, “A” indicates normal, and “X” indicates slow. A high solder wetting and spreading speed facilitates the formation of a uniform solder film, and as a result, a strong bond can be formed.

Solder joint strength: measured by the Scotch tape method. Specifically, a tape is applied to the solder surface, and the ratio of the solder layer remaining when the tape is peeled off (the area of the remaining solder layer / the area of the solder layer before the tape is peeled) × 100 (%) is measured. The residual ratio was indicated as ◎ for 90% or more, ○ for 70% or more and less than 90%, and × for less than 70%.
The results are as shown in Table 1.

<Examples 2 to 5 and Comparative Examples 1 to 4>
A multilayer probe pin was manufactured in the same manner as in Example 1 except that the central member, the insulating coating layer, the conductive metal layer, and the conductive thin film layer were changed as shown in Table 1.

The results are as shown in Table 1.

  As shown in Table 1, it was found that those provided with a conductive thin film layer (plating layer) of Ra 30 μm or less had good solder wettability and bonding strength. In particular, it was found that when Ra is 3 μm or less, not only solder wettability but also bonding strength is high.

Sectional drawing which shows one preferable specific example of the multilayer type probe pin by this invention Top view of the probe card of the present invention The perspective view of the probe card of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multilayer type probe pin 2 Center member 3 Insulating layer 4 Conductive metal layer 5 Conductive thin film layer 6 Probe card board

Claims (7)

A probe pin in which a central member, an insulating layer covering the central member, and a conductive metal layer made of a metal material mainly composed of Cu formed on the outer peripheral surface of the insulating layer are combined.
The thickness of the conductive metal layer is 0.4 mm or more and 0.8 mm or less, the surface roughness of the conductive metal layer is Ra 30 μm or less, and at least part of the surface of the conductive metal layer is Sn. A multi-layered probe pin, wherein a conductive thin film layer made of a metal material containing as a main component is formed.   The multilayer probe pin according to claim 1, wherein the conductive thin film layer is formed at a joint portion when the multilayer probe pin is joined to a probe card.   The center member is made of a metal material containing at least one of W, Mo, Re, Ta, Nb, Au, Ag, Pt, Ni, Co, and Cu as a main component. The multilayer probe pin described. Said insulating layer and said conductive metal layer, caulking, epoxy welding, shrink fit, are joined by either brazing, multi probe pin according to any one of claims 1-3. The multilayer probe pin according to any one of claims 1 to 4 , wherein a layer thickness of the conductive thin film layer is 0.1 µm or more and 50 µm or less. The conductive thin film layer is a plating film, multilayer probe pin according to any one of claims 1-5.   A probe card in which the multilayer probe pin according to any one of claims 1 to 6 is joined by lead-free solder.

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