JP2014107390A - Wiring board and multilayer wiring board using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring board having high connection reliability and a multilayer wiring board using the same.SOLUTION: A wiring board 1 of the present invention includes a laminate 2, through conductors 3, and thin-film conductor layers 4. The laminate 2 is formed by laminating a plurality of resin insulating layers 2a. The through conductors 3 are provided in the resin insulating layers 2a. The thin-film conductor layers 4 are provided on surfaces of the resin insulating layers 2a and are connected to the through conductors 3. Each of the through conductors 3 includes a through conductor body 3a and a projecting end 3b. The projecting end 3b abuts on each of the thin-film conductor layers 4 and projects from the through conductor body 3a in a layer direction of the resin insulating layers 2a.

Description

  The present invention relates to a wiring board and a multilayer wiring board using the wiring board.

  Conventionally, multilayer wiring boards have been used as wiring boards used for mounting electronic components. Such a wiring board is made of, for example, a polyimide resin or the like on the upper surface of a circuit board made of a ceramic substrate or the like, and is formed by applying a resin precursor by a curtain coat method or a spin coat method and then heat-curing the resin substrate. Resin insulation layer and thin film conductor layer and wiring conductor layer made of metal such as copper or aluminum and formed by adopting thin film formation technology such as plating method or vapor deposition method and photolithography technology alternately The circuit conductor of the circuit board is electrically connected to the end surface of the through conductor exposed on one main surface side of the resin insulation layer, and the other main surface side of the resin insulation layer. An electrode of an electronic component such as a semiconductor integrated circuit element or a probe for performing an electrical inspection of the electronic component is connected to the exposed end face of the through conductor. And an electronic component is electrically connected with the circuit conductor of a circuit board through a penetration conductor, and transmission / reception of a signal, an electrical test | inspection with respect to an electronic component, etc. are performed.

Japanese Patent Laid-Open No. 11-160356

  For example, a multilayer wiring board used for a probe card is caused by stress applied to the resin insulation layer and the thin film conductor layer when an external force is applied at the connection between the through conductor and the thin film conductor layer during use such as electrical inspection. In some cases, electrical connection between the through conductor and the thin film conductor layer cannot be maintained, or the through conductor and the thin film conductor layer are disconnected.

  A wiring board according to an aspect of the present invention includes a laminate, a through conductor, and a thin film conductor layer. The laminate is formed by laminating a plurality of resin insulating layers. The through conductor is provided in the resin insulating layer. The thin film conductor layer is provided on the surface of the resin insulating layer and connected to the through conductor. The through conductor includes a through conductor main body and a protruding end. The protruding end is in contact with the thin film conductor layer and protrudes from the through conductor body in the layer direction of the resin insulating layer.

  According to another aspect of the present invention, a multilayer wiring board includes a ceramic substrate and the wiring substrate having the above-described configuration stacked on the upper surface of the ceramic substrate.

  In the wiring board according to one aspect of the present invention, the protruding end is in contact with the thin film conductor layer, and protrudes in the layer direction of the resin insulating layer from the through conductor main body, whereby the through conductor and the thin film conductor layer are formed. When the contact area is increased and the through conductor and thin film conductor layer are firmly joined, and an external force is applied during use such as electrical inspection, stress is applied to the resin insulation layer and thin film conductor layer. However, it is possible to prevent the through conductor and the thin film conductor layer from being disconnected, and the connection reliability between the through conductor and the thin film conductor layer can be improved.

According to another aspect of the present invention, the multilayer wiring board includes a ceramic substrate and the wiring substrate having the above-described configuration laminated on the upper surface of the ceramic substrate, thereby improving connection reliability.

(A) is sectional drawing which shows the wiring board and multilayer wiring board in embodiment of this invention, (b) is sectional drawing which expands and shows the A section of the wiring board shown by Fig.1 (a). . FIG. 2 is a plan perspective view showing the wiring board shown in FIG.

  Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings.

  A wiring board according to an embodiment of the present invention will be described with reference to FIGS. The wiring board 1 in this embodiment includes a multilayer body 2, a through conductor 3, and a thin film conductor layer 4. 1 and 2, the wiring board and the multilayer wiring board are provided in a virtual XYZ space, and hereinafter, the “upward direction” means the positive direction of the virtual Z axis for convenience.

  The laminate 2 is formed by laminating a plurality of resin insulating layers 2a. The resin insulating layer 2a is made of an insulating resin such as polyimide resin, polyphenylene sulfide resin, wholly aromatic polyester resin, BCB (benzocyclobutene) resin, epoxy resin, bismaleimide triazine resin, polyphenylene ether resin, polyquinoline resin, or fluororesin. It consists of

For example, when the resin insulating layer 2a is made of a polyimide resin, a varnish-like polyimide precursor is applied to the upper surface of the ceramic substrate 11 described later by a coating method such as a spin coating method, a die coating method, a curtain coating method, or a printing method. Thereafter, it is cured with heat of about 400 ° C. to be polyimideized to form a thickness of about 10 μm to 50 μm. Alternatively, a resin adhesive such as a siloxane-modified polyamideimide resin, a siloxane-modified polyimide resin, a polyimide resin, a bismaleimide triazine resin, or an epoxy resin is dried on the lower surface of a sheet of about 10 μm to 50 μm made of the above resin with a dry thickness of about 5 μm to 20 μm. An adhesive layer is formed by applying and drying on a coating method such as a doctor blade method, and the adhesive layer is formed on the ceramic substrate 11 by heating and pressing. In any method, the plurality of resin insulation layers 2a are formed by forming the through conductors 3 and the thin film conductor layers 4 in the resin insulation layer 2a and repeating the above steps as many times as the required number of resin insulation layers 2a. In the method using a resin for a film, a plurality of films can be pressed at once, and it is not necessary to apply and cure for each layer, so that the manufacturing process can be shortened.

In the laminated body 2, the through conductor 3 is provided in the resin insulating layer 2a. For example, a through hole having a diameter of 20 μm to 100 μm is formed in the resin insulating layer 2a. The through hole is formed by first forming a resist film having an opening in the resin insulating layer 2a and etching the resin insulating layer 2a located in the opening of the resist film or directly using a laser. It is formed by removing a part of. As the laser at this time, an excimer laser, a CO ₂ laser, or the like can be used. However, the shape of the inner wall of the through hole can be adjusted almost vertically, and the inner wall surface of the through hole can be formed with an ultraviolet laser that can be processed smoothly. Is desirable. Alternatively, in the case of a method of applying a varnish-like resin, a photosensitive resin is used, for example, a portion other than a portion where a through-hole is formed by exposure is cured, and a resin in a portion where the through-hole is formed is obtained. The through hole may be formed by removing by etching.

In the laminated body 2, the thin film conductor layer 4 is provided between the resin insulating layers 2 a or the outermost layer, and is connected to the through conductor 3. The thin film conductor layer 4 is formed on the entire main surface of the resin insulating layer 2a by a thin film forming method such as a vapor deposition method, a sputtering method, or an ion plating method.
A base conductor layer made of, for example, a chromium (Cr) -Cu alloy layer or a titanium (Ti) -Cu alloy layer having a thickness of about 3 μm to 3 μm is formed. Next, a resist film having a pattern-shaped opening of the thin film conductor layer 4 is formed on the underlying conductor layer, and the resist film is used as a mask to form a metal having a low electrical resistance such as copper or gold by plating or the like. A main conductor layer having a thickness of about 10 μm is formed. Then, the resist film is peeled and removed, and the exposed portion of the underlying conductor layer is removed by etching, whereby the thin film conductor layer 4 is formed. On the surface of the thin film conductor layer 4 provided on the upper surface of the multilayer body 2, a nickel plating layer with a thickness of about 1 to 10 μm and a gold with a thickness of about 0.1 to 3 μm are used for corrosion prevention or connectivity with a probe. The plating layer may be formed sequentially.

  Moreover, in the laminated body 2, it has a location which becomes concave by carrying out mechanical polishing or etching with respect to the thin film conductor layer 4 formed in the resin insulating layer 2a.

  Before forming the thin film conductor layer 4, the through conductor body 3 a is formed by filling the through hole of the resin insulating layer 2 a with, for example, a conductor paste mainly composed of metal powder such as copper and a resin or melted solder. As a result, a through hole filled with a conductor is formed as in the example shown in FIG. In addition, it is preferable that the through hole is shaped so that the lower surface side of the insulating resin layer 2 is larger so that the conductor can be satisfactorily filled into the through hole. The through hole having such a shape is controlled by etching conditions when the through hole is formed by etching, by adjusting the output of the laser when the through hole is formed by a laser, or by exposure condition or etching when a photosensitive resin is used. It can be formed depending on conditions.

  In the wiring substrate 1 of the present embodiment, a laminate 2 in which a plurality of resin insulation layers 2a are laminated, a through conductor 3 provided on the resin insulation layer 2a, and a surface provided on the surface of the resin insulation layer 2a. A thin-film conductor layer 4 connected to the conductor 3, the through-conductor 3 includes a through-conductor body 3a and a protruding end 3b, and the protruding end 3b is in contact with the thin-film conductor layer 4, It protrudes from the through conductor body 3a in the layer direction of the resin insulating layer 2a.

  Thus, the through conductor 3 includes the through conductor main body 3a and the protruding end portion 3b, the protruding end portion 3b is in contact with the thin film conductor layer 4, and protrudes from the through conductor main body 3a in the layer direction of the resin insulating layer 2a. As a result, the contact area between the penetrating conductor 3 and the thin film conductor layer 4 is increased, and the penetrating conductor 3 and the thin film conductor layer 4 are firmly joined. Can be prevented even if stress is applied to the resin insulating layer 2a and the thin film conductor layer 4, the through conductor 3 and the thin film conductor layer 4 can be prevented from being disconnected. The connection reliability with the layer 4 can be improved. The “layer direction” refers to a direction parallel to the X axis and the Y axis in FIGS.

The through conductor 3 has a concave portion formed by mechanical polishing or etching in the thin film conductor layer 4 formed in the resin insulation layer 2a, and the resin insulation layer 2a in which the through conductor body 3a is formed; By laminating the resin insulating layer 2a on which the thin film conductor layer 4 is formed so that the through conductor body 3a and the thin film conductor layer 4 are connected to each other, the conductor paste filled in the through conductor body 3a or melted. A protruding conductor 3b is formed by filling a concave portion of the thin film conductor layer 4 with a conductor such as solder. The through conductor 3 formed in this way has a connection surface connected to the thin film conductor layer 4, and the connection surface is convex, that is, convex in a longitudinal sectional view. When an external force is applied during use such as inspecting, even if stress is applied to the resin insulating layer 2a and the thin-film conductor layer 4, the connection surface between the through conductor 3 and the thin-film conductor layer 4 that is liable to peel off is curved. When viewed in a longitudinal cross section, the shape is curved, the contact area between the through conductor 3 and the thin film conductor layer 4 is increased, and the through conductor 3 and the thin film conductor layer 4 are firmly joined. It is possible to prevent the conductor layer from being disconnected. In addition, in the thin film conductor layer 4 formed in the outermost layer, after preparing a plate-like support body with a smooth surface in advance and forming the thin film conductor layer 4 on the support body, the thin film formed on the support body A concave portion is formed in the conductor layer 4 by mechanical polishing or etching, and the resin insulating layer 2a on which the through conductor body 3a is formed and the support on which the thin film conductor layer 4 is formed are connected to the through conductor. By laminating the main body 3a and the thin film conductor layer 4 so as to be connected, the conductor paste filled in the through conductor main body 3a or a conductor such as molten solder is filled in the concave portion of the thin film conductor layer 4 Thus, the protruding end 3b is formed.

  As shown in FIGS. 1 and 2, the thin film conductor layer 4 is formed so as to cover the protruding end 3b. With such a configuration, when an external force is applied during use such as electrical inspection, the resin insulating layer 2a and the thin film conductor layer 4 can be easily concentrated even if stress is applied to the resin insulating layer 2a and the thin film conductor layer 4. Thus, the connection surface between the through conductor 3 and the thin film conductor layer 4 is disposed at a different location, and the through conductor and the thin film conductor layer can be prevented from being disconnected.

The ceramic substrate 11 on which the wiring substrate 1 is laminated on the upper surface includes a ceramic insulating layer 11a. The ceramic insulating layer 11a includes an aluminum oxide (alumina: Al ₂ O ₃ ) sintered body, an aluminum nitride (AlN) sintered body, a silicon carbide (SiC) sintered body, a mullite sintered body, a glass ceramic, and the like. It is made of ceramics. When used for a probe card, an aluminum oxide (Al ₂ O ₃ ) sintered material or glass ceramics having a thermal expansion coefficient close to that of silicon (Si) forming a wafer is preferable. When the ceramic insulating layer 8 is made of such ceramics, when the probe is bonded onto the wiring substrate 1, the heat of the wiring substrate 1 and the wafer bonded together with the probe, which is added to the probe or the bonded portion of the probe. This is preferable because the thermal stress due to the expansion difference is relatively small. Further, when used as a probe card, it is possible to effectively prevent thermal deformation with respect to a thermal load during measurement of electrical characteristics of a semiconductor element, and furthermore, heat is not retained inside due to high heat transferability.

  The internal wiring 12 and the external wiring 13 of the ceramic substrate 11 are formed by simultaneous firing with the ceramic insulating layer 11a, tungsten (W), molybdenum (Mo), molybdenum-manganese (Mo-Mn) alloy, silver (Ag), It is made of metallization mainly composed of metal such as copper (Cu), gold (Au), silver-palladium (Pd) alloy.

  Such a ceramic substrate 11 is manufactured by the following method. For example, when the ceramic insulating layer 11a is formed of an aluminum oxide sintered body, first, an appropriate organic binder and solvent are added to and mixed with raw material powders of aluminum oxide, silicon oxide, magnesium oxide and calcium oxide, and the slurry is mixed. This is formed into a sheet shape by a doctor blade method or the like to produce a plurality of ceramic green sheets to be the ceramic insulating layer 11a.

  Next, a through hole is formed by a suitable punching process at a predetermined position where the internal through conductor of the ceramic green sheet is formed, and the through hole is filled with a conductive paste. Further, a conductor paste layer serving as an internal wiring layer is formed to a thickness of 10 to 20 μm at a predetermined position of the ceramic green sheet by a screen printing method or the like. The conductive paste is produced by kneading a metal powder having a high melting point such as tungsten (W), molybdenum (Mo), molybdenum-manganese (Mo-Mn) alloy, an appropriate resin binder, and a solvent.

Finally, these ceramic green sheets are superposed and pressure-bonded to produce a laminate, and this laminate is fired at a high temperature of about 1500 ° C. to 1600 ° C. to produce the ceramic substrate 11. When a nickel plating layer having a thickness of about 1 to 10 μm and a gold plating layer having a thickness of about 0.1 to 3 μm are sequentially formed on the surface of the external wiring 13 of the ceramic substrate 11 in order to prevent corrosion or to connect to an external circuit. Good. A similar plating layer may be formed on a portion of the internal wiring 12 (internal through conductor) exposed on the surface of the ceramic substrate 11.

The multilayer wiring board includes a ceramic substrate 11 and the wiring substrate 1 having the above-described structure, which is laminated on the upper surface of the ceramic substrate 11. Further, the probe card includes the multilayer wiring board configured as described above and a probe connected to the thin film conductor layer 4 on the upper surface of the wiring board 1.

  For example, the probe is connected to the wiring board 1 of the present embodiment as follows. First, a female die of a plurality of probes is formed on one surface of a silicon wafer by etching. Next, a metal made of nickel is applied to the surface on which the female mold is formed by plating, and the female mold is embedded with nickel, and nickel on the wafer other than the embedded portion is removed by processing such as etching. Then, a silicon wafer having a nickel probe embedded therein is produced. The nickel probe embedded in the silicon wafer is bonded to the thin film conductor layer 4 on the upper surface of the wiring substrate 1 with a bonding material such as solder. Then, by removing the silicon wafer with an aqueous potassium hydroxide solution, a probe card in which the probe is connected to the thin film conductor layer 4 on the upper surface of the wiring substrate 1 laminated on the upper surface of the ceramic substrate 11 is obtained.

  In the wiring board 1 of the present embodiment, the through conductor 3 includes a through conductor main body 3a and a protruding end 3b, the protruding end 3b is in contact with the thin film conductor layer 4, and the resin insulating layer 2a from the through conductor main body 3a. Projecting in the layer direction, the contact area between the through conductor 3 and the thin film conductor layer 4 is increased, and the through conductor 3 and the thin film conductor layer 4 are firmly bonded to each other for electrical inspection. When an external force is applied during use, it is possible to prevent the through conductor 3 and the thin film conductor layer 4 from being disconnected even if stress is applied to the resin insulating layer 2a and the thin film conductor layer 4. The connection reliability between the conductor 3 and the thin film conductor layer 4 can be improved.

  The multilayer wiring board of the present embodiment is improved in connection reliability by including the ceramic substrate 11 and the wiring substrate 1 having the above-described configuration laminated on the upper surface of the ceramic substrate 11.

DESCRIPTION OF SYMBOLS 1 ... Wiring board 2 ... Laminated body 2a ... Resin insulation layer 3 ... Penetration conductor 3a ... Penetration conductor main body 3b ... Projection end part 4. .... Thin film conductor layers
11 ... Ceramic substrate

Claims (4)

A laminate in which a plurality of resin insulation layers are laminated;
A through conductor provided in the resin insulation layer;
A thin film conductor layer provided on the surface of the resin insulation layer and connected to the through conductor;
The through conductor includes a through conductor body and a protruding end,
The protruding end portion is in contact with the thin film conductor layer and protrudes from the through conductor body in the layer direction of the resin insulating layer. The through conductor has a connection surface connected to the thin film conductor layer,
The wiring board according to claim 1, wherein the connection surface is convex in a longitudinal sectional view.   The wiring board according to claim 1, wherein the thin film conductor layer is formed so as to cover the protruding end portion. A ceramic substrate;
A multilayer wiring board comprising: the wiring board according to claim 1, wherein the multilayer wiring board is laminated on an upper surface of the ceramic substrate.

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