JP2013191678A - Multilayer wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer wiring board which has high joining strength between a junction member and a wiring conductor.SOLUTION: A multilayer wiring board includes: multiple insulation layers 1 laminated with each other; wiring layers 2, each of which is provided between the multiple insulation layers 1; and via conductors 4, each of which is electrically connected with the wiring layer 2 by a junction member 3 made of a metal material. In a vertical cross section view, a width Wof the junction member 3 is smaller than a width Wof the via conductor 4. Each via conductor 4 is provided in a vertical direction in the insulation layer 1 that is provided on the wiring layer 2 among the multiple insulation layers 1.

Description

  The present invention relates to a multilayer wiring board having a plurality of insulating layers stacked on each other and a wiring layer provided between the plurality of insulating layers.

  Conventionally, a plurality of insulating layers, a wiring layer provided between the plurality of insulating layers, and an insulating layer provided on the wiring layer among the plurality of insulating layers are provided in the vertical direction. A wiring board having a via conductor electrically connected to a wiring layer by a joining member is known (see, for example, Patent Document 1). As such a wiring substrate, for example, a space transformer substrate is known in which a semiconductor element is connected to a terminal on the upper surface, and a connection pad on the lower surface electrically connected to the terminal is electrically connected to an external electric circuit. .

  As a space transformer substrate, for example, a multilayer wiring substrate in which a thin film wiring layer is laminated on an upper surface of a ceramic substrate is known. In such a space transformer substrate, a via conductor and a wiring layer are provided in the thin film wiring layer and the ceramic substrate, respectively. The via conductor of the thin film wiring layer and the wiring layer of the thin film wiring layer, or the via conductor of the thin film wiring layer and the wiring layer of the ceramic substrate are joined by a joining member.

JP 2003-218531 A

  However, in the above-described conventional multilayer wiring board, the adhesion strength between the bonding member and the wiring layer is low due to insufficient pressure when the lamination pressure is applied, and the bonding strength between the bonding member and the wiring layer may be low. . When the bonding strength between the bonding member and the wiring layer is low, delamination may occur at the boundary surface between the bonding member and the wiring layer, which may hinder the electrical connection between the wiring layer and the via conductor. .

  A multilayer wiring board according to one aspect of the present invention is electrically connected to a wiring layer by a plurality of insulating layers stacked on each other, a wiring layer provided between the plurality of insulating layers, and a bonding member made of a metal material. The width of the joining member is smaller than the width of the via conductor in a longitudinal sectional view. The via conductor is provided in the vertical direction in the insulating layer provided on the wiring layer among the plurality of insulating layers.

  According to the multilayer wiring board according to one aspect of the present invention, the width of the joining member is smaller than the width of the via conductor in the longitudinal sectional view, and therefore has a width smaller than that of the via conductor when the lamination pressure is applied. The force concentrates on the lower end portion of the joining member, and the adhesion strength between the joining member and the wiring layer is improved. Therefore, the bonding strength between the via conductor and the wiring layer is improved.

It is sectional drawing which shows the multilayer wiring board in the 1st Embodiment of this invention. (A) is a principal part expanded sectional view which expands and shows the A section of FIG. 1, (b) is a principal part expanded sectional view which expands and shows the B section of FIG. (A) And (b) is a principal part expanded sectional view which expands and shows the principal part of the multilayer wiring board in the 2nd Embodiment of this invention.

  Several exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

(First embodiment)
The multilayer wiring board according to the first embodiment of the present invention is provided between a plurality of insulating layers 1 and a plurality of insulating layers 1 stacked together as in the example shown in FIGS. 1 and 2. The wiring layer 2 has a via conductor 4 electrically connected to the wiring layer 2 by a bonding member 3 made of a metal material. The insulating layer 1 includes a ceramic substrate 11 and a thin film wiring layer 12. The insulating layer 1 has a thin film wiring layer 12 bonded to a ceramic substrate 11 by a bonding layer 5. The wiring layer 2 includes a wiring conductor 21 provided on the ceramic substrate 11 and a thin film conductor layer 22 provided on the thin film wiring layer 12.

  The ceramic substrate 11 has a function of ensuring the rigidity of the entire multilayer wiring board. Multilayer wiring that can be used for probe cards, etc., in which fine wiring that can correspond to the electrodes of semiconductor elements is provided on a highly rigid substrate by providing the thin film wiring layer 12 on the ceramic substrate 11 A substrate can be formed. When used as a probe card, the multilayer wiring board is pressed against the semiconductor element with a predetermined pressure in order to ensure electrical connection to the semiconductor element.

  The ceramic substrate 11 is, for example, an aluminum oxide sintered body or an aluminum nitride sintered body, a mullite sintered body, a glass ceramic sintered body, crystallized glass or mica or titanium in which crystal components are precipitated in a glass base material. A microcrystalline sintered body such as aluminum oxide can be used as a material. Such a ceramic material is a so-called machinable ceramic that can be machined substantially as accurately as a metal material.

  If the ceramic substrate 11 is made of, for example, an aluminum oxide sintered body, it can be manufactured as follows. First, a ceramic green sheet is formed by forming a slurry prepared by adding and mixing an appropriate organic binder and organic solvent to raw material powders such as aluminum oxide and silicon oxide into a sheet shape by a sheet forming technique such as a doctor blade method or a lip coater method. Is made. Thereafter, the ceramic green sheet can be made into a suitable shape and size by cutting or punching, and can be manufactured by firing at a temperature of about 1300 to 1500 ° C.

  A wiring conductor 21 is provided on the upper surface of the ceramic substrate 11. The wiring conductor 21 is electrically connected to the thin film wiring layer 12 through the bonding member 3. Further, the wiring conductor 21 is electrically connected to the connection pad 6 provided on the lower surface of the ceramic substrate 11 through an internal conductor such as a through conductor provided in the ceramic substrate 11.

  The wiring conductor 21, the inner conductor, and the connection pad 6 are made of a metal material such as tungsten, molybdenum, manganese, copper, silver, palladium, gold, or platinum. Note that a plurality of these metal materials may be used together in the form of an alloy or the like. These metal materials are attached to predetermined portions of the ceramic substrate 11 by a method such as a metallization method or a plating method.

If the wiring conductor 21, the inner conductor and the connection pad 6 are made of tungsten, for example, a paste of tungsten is applied to the surface of the ceramic green sheet to be the ceramic substrate 11 or the inside of a previously formed through hole. It can be applied by filling and cofiring with the ceramic green sheet.

A via conductor 4 is provided inside the ceramic substrate 11. The via conductor 4 can be made of the same material as the wiring conductor 21 described above. The via conductor 4 of the ceramic substrate 11 has a through-hole (not indicated) penetrating in the thickness direction in a part of the ceramic substrate 11 by laser processing using a CO ₂ laser or YAG laser, punching processing using a punching die, or the like. It can be formed by filling the through hole with a conductive material to be the via conductor 4 by a method such as sputtering, vapor deposition, plating, or filling of a conductive paste.

  The via conductor 4 of the ceramic substrate 11 is filled with, for example, a metal paste prepared by kneading the metal material powder for the via conductor 4 with an organic solvent and a binder in the through hole of the ceramic substrate 11, and then heated. It can be formed by removing the organic component. In this case, a metal film forming technique such as plating or sputtering may be used in combination.

The thin film wiring layer 12 has a structure in which a thin film conductor layer 22 is attached to the surface of the resin insulating layer 121 and the via conductor 4 is provided inside the resin insulating layer 121. The thin film conductor layer 22 and the via conductor 4 are made of, for example, a metal material such as copper, silver, palladium, gold, platinum, aluminum, chromium, nickel, cobalt, titanium, or an alloy material of these metal materials.

The thin film wiring layer 12 has a structure in which thin film conductor layers 22 and resin insulating layers 121 are alternately stacked. The thin film conductor layers 22 on the surface of the resin insulation layer 121 are electrically connected to each other through via conductors 4 provided in the vertical direction in the resin insulation layer 121. The via conductor 4 and the thin film conductor layer 22 provided in different resin insulating layers 121 are joined by the joining member 3. The plurality of resin insulating layers 121 are bonded to each other by the bonding layer 5. The details of the bonding member 3 and the bonding layer 5 will be described later.

The thin film conductor layer 22 is formed by depositing the above metal material on the main surface of the resin insulating layer 121 by a method such as sputtering, vapor deposition, or plating, and performing trimming processing such as masking or etching as necessary. Further, it can be formed on the surface of the resin insulating layer 121 in a predetermined pattern.

The resin insulating layer 121 functions as a base material for forming the thin film conductor layer 22. The resin insulating layer 121 functions as an insulating material for ensuring electrical insulation between the thin film conductor layers 22.

The resin insulation layer 121 is, for example, a rectangular shape such as a rectangular shape or a square shape, or a circular shape.
It is provided in a layered form with a thickness of about 25 μm. Such a resin insulating layer 121 can be made of, for example, a resin such as an epoxy resin, a polyimide resin, a polyamideimide resin, a polyetherimide resin, or a liquid crystal polymer.

The resin insulating layer 121 can be produced, for example, by forming an uncured product of the resin material into a layer and curing it. In molding an uncured resin material, a resin film such as a polyethylene resin may be used as a molding substrate. If the base material is removed after the resin material is cured, the resin insulating layer 121 formed into a layer can be obtained.

The via conductor 4 of the resin insulating layer 121 is formed in the thickness direction by, for example, drilling such as laser processing using a CO ₂ laser or YAG laser, RIE (reactive ion etching) or etching using a solvent on a part of the resin insulating layer 121 Forming through-holes (without reference numerals) that pass through, and filling the through-holes with a conductive material to be via conductors 4 by a method such as sputtering, vapor deposition, plating, or filling with a conductive paste. Can do.

The via conductor 4 of the resin insulating layer 121 is filled with, for example, a metal paste prepared by kneading the metal material powder for the via conductor 4 with an organic solvent and a binder in the through hole of the resin insulating layer 121, and then heated. Then, it can be formed by removing the organic component. In this case, a metal film forming technique such as plating or sputtering may be used in combination.

The thin film wiring layer 12 is produced as follows. First, a plurality of resin insulation layers 121 provided with the thin film conductor layer 22 and the via conductor 4 are prepared. The joining member 3 is disposed at the lower end portion of the via conductor 4. Next, a plurality of resin insulating layers 121 are stacked on each other so that the lower end portion of the bonding member 3 and the thin film conductor layer 22 are in contact with each other. Thereafter, the plurality of laminated resin insulating layers 121 are heated and pressurized,
A thin film wiring layer 12 is produced. Note that the resin insulating layer 121 positioned at the bottom when the layers are stacked may be provided on a molding substrate made of a resin film such as a polyethylene resin, and the substrate after the resin insulating layer 121 is stacked. Can be removed.

  The thin film conductor layer 22 provided on the uppermost surface of the thin film wiring layer 12 is for electrical connection with, for example, an electrode of a semiconductor element via a probe 7. A via conductor 4 provided so as to be exposed at the lowermost surface of the thin film wiring layer 12 is directly connected to the upper end portion of the bonding member 3.

  In the multilayer wiring board of the present embodiment, the lower end portion of the joining member 3 is joined to and electrically connected to the wiring conductor 21 of the ceramic substrate 11, so that the semiconductor element electrically connected to the thin film conductor layer 22 These electrodes are electrically connected to the connection pads 6 on the lower surface of the ceramic substrate 11. If this connection pad 6 is electrically connected to an electrical circuit for inspection, an electrical inspection of the semiconductor element (whether or not normal operation or storage or the like is performed) can be performed. Examples of the semiconductor element include a semiconductor integrated circuit element such as an IC or LSI, a micromachine (so-called MEMS element) in which a minute electromechanical mechanism is provided on the surface of a semiconductor substrate, and the like.

As in the example shown in FIGS. 1 and 2, the joining member 3 has the upper end portion and the via conductor 4 joined in a longitudinal sectional view, and the lower end portion and the thin film wiring layer 12 or the wiring conductor 21 are joined. Has been. The width W ₁ of the joining member 3 is smaller than the width W ₂ of the via conductor 4 in a longitudinal sectional view. Such a joining member 3 has an area smaller than that of the via conductor 4 in a plan view, for example. Further, the entire joining member 3 overlaps with the via conductor 4 in a plan view. A bonding layer 5 is provided around the periphery of the bonding member 3 excluding the upper end and the lower end.

Thus, in the longitudinal sectional view, since the width W ₁ of the bonding member 3 is smaller than the width W ₂ of the via conductor 4, a force is applied to the lower end portion of the bonding member 3 when a lamination pressure is applied to the multilayer wiring board. Since it concentrates, the multilayer wiring board by which the adhesive strength of the joining member 3 and the wiring conductor 21 (wiring layer 2) was improved is obtained.

  The material of the joining member 3 is, for example, gold (Au), silver (Ag), zinc (Zn), tin (Sn), copper (Cu), and a metal mainly composed of these alloys.

  When such a joining member 3 is provided between the via conductor 4 and the wiring conductor 21, for example, the plate-like or paste-like metal material is disposed in a through-hole provided in the joining layer 5. To be provided. Further, when the bonding member 3 is provided between the via conductor 4 and the thin film conductor layer 22, for example, the bonding member 3 is formed by plating at a portion where the via conductor 4 is exposed from the thin film wiring layer 12.

The width W ₁ of the bonding member 3 is smaller than the width W ₂ of the via conductor 4 in the thin film wiring layer 12 in a longitudinal sectional view. Therefore, the bonding member 3 at the lower end of the via conductor 4 can increase the bonding strength with the thin film conductor layer 22 having a small area provided in the thin film wiring layer 12.

In the multilayer wiring board of this embodiment, the thermal expansion coefficient of the thin film wiring layer 12 is larger than the thermal expansion coefficient of the ceramic substrate 11. In such a multilayer wiring board of this embodiment, the width W ₁ of the bonding member 3 between the ceramic substrate 11 and the thin film wiring layer 12 in the longitudinal sectional view is the width W of the via conductor 4 of the thin film wiring layer 12. ₂ and the wiring conductor 21 are preferably smaller. Even if the joining location between the joining member 3 and the via conductor 4 is shifted in plan view due to the difference in thermal expansion between the ceramic substrate 11 and the thin film wiring layer 12, the entire lower end portion of the joining member 3 can be pressurized. The bonding strength between the member 3 and the wiring conductor 21 can be increased.

  The bonding layer 5 between the ceramic substrate 11 and the thin film wiring layer 12 preferably has a structure in which materials having different elastic moduli are laminated. That is, the elastic modulus of the adhesive layer on the ceramic substrate 11 side is preferably larger than the elastic modulus of the adhesive layer on the thin film wiring layer 12 side. In such a case, since the bonding layer 5 is more easily deformed on the ceramic substrate 11 side than on the thin film wiring layer 12 side, the lower end portion is surrounded by the lower end portion than the upper end portion of the bonding member 3 when pressurizing the multilayer wiring substrate. Since the pressure is applied from the bonding layer 5, it is possible to suppress the deformation so that the width of the lower end portion of the bonding member 3 is widened. Therefore, it is more effective to concentrate the force on the lower end portion of the joining member 3 and improve the adhesion strength between the joining member 3 and the wiring conductor 21.

The bonding layer 5 is for bonding the thin film wiring layer 12 on the ceramic substrate 11 or bonding the resin insulating layer 121 to each other. The bonding layer 5 is provided so as to surround the periphery of the bonding member 3 except for the upper end portion and the lower end portion thereof. The multilayer wiring board in which the thin-film wiring layer 12 is bonded to the ceramic substrate 11 via the bonding layer 5 is excellent in productivity or practicality (so-called multi-product correspondence). That is, since a multilayer wiring board is manufactured by bonding the separately prepared ceramic substrate 11 and the thin film wiring layer 12 via the bonding layer 5, the thin film wiring layer 12 is directly laminated on the upper surface of the ceramic substrate 11. Compared to the above, a multilayer wiring board can be easily manufactured. In addition, since the thin film wiring layers 12 of various patterns can be prepared together, so-called multi-product correspondence is easy. Note that the thickness of the bonding layer 5 is, for example, about 5 to 20 μm.

  The bonding layer 5 can be made of a thermosetting resin such as a polyimide resin, a polyquinoline resin, a polyamideimide resin, an epoxy resin, or a fluorine resin.

  The example of the formation method of the joining layer 5 is described below. First, the bonding layer 5 is disposed so as to adhere to the lower surface of the thin film wiring layer 12 in an uncured state. Next, the thin film wiring layer 12 having the lower surface bonded to the bonding layer 5 is set on the upper surface of the ceramic substrate 11. Thereafter, if each thermosetting resin material of the bonding layer 5 is heated and cured, the thin film wiring layer 12 can be laminated on the ceramic substrate 11 via the bonding layer 5 and bonded. In addition, the adhesiveness between the ceramic substrate 11 and the thin film wiring layer 12 and the bonding layer 5 is enhanced by applying pressure downward from the upper surface side of the thin film wiring layer 12 during the bonding.

  Here, the bonding process between the ceramic substrate 11 and the thin film wiring layer 12 through the bonding layer 5 will be described more specifically.

  First, the ceramic substrate 11 and the thin film wiring layer 12 are produced. The ceramic substrate 11 and the thin film wiring layer 12 can be produced, for example, by the method described above.

  Next, the bonding layer 5 is produced. The bonding layer 5 forms a through hole after the bonding layer 5 is formed on a resin film such as a polyethylene film. The through hole also penetrates the resin film. If the resin film is removed after the through holes are formed, the bonding layer 5 can be produced. In this step, the bonding layer 5 is in a semi-cured state.

  The through-hole penetrating the bonding layer 5 and the resin film can be formed by, for example, the same method (laser processing or etching) as that for forming the via conductor 4 in the thin film wiring layer 12 described above.

  The produced bonding layer 5 is aligned and bonded onto the thin film wiring layer 12 so that the end of the bonding member 3 and the via conductor 4 of the thin film wiring layer 12 face each other.

  Moreover, the joining member 3 is formed by arranging the plate-like solder material made of the above-described metal material on the wiring conductor 21 so as to be located in the through hole.

  Thereafter, the bonding layer 5 bonded to the thin film wiring layer 12 is turned upside down and laminated on the upper surface of the ceramic substrate 11, and the bonding layer 5 and the bonding member 3 are heated and cured to thereby form the thin film wiring layer 12. And the ceramic substrate 11 are joined. In this case, alignment is performed so that the end portion of the joining member 3 and a predetermined portion of the wiring conductor 21 face each other.

  Further, as described above, during this bonding, pressure is applied downward from the upper surface side of the thin film wiring layer 12 using a press machine or the like. By this pressurization, the adhesion between the ceramic substrate 11 and the thin film wiring layer 12 and the bonding layer 5 can be improved.

Here, since the width W ₁ of the joining member 3 is smaller than the width W ₂ of the via conductor 4 in a longitudinal sectional view, the force applied from the via conductor 4 to the joining member 3 by the pressurization is the lower end portion of the joining member 3. Therefore, the adhesion strength between the joining member 3 and the wiring conductor 21 is improved.

  The multilayer wiring board described above is used as a probe card for electrical inspection of semiconductor elements, for example, as described above. The thin film conductor layer 22 provided on the uppermost surface of the thin film wiring layer 12 is electrically connected to the electrodes of the semiconductor element via the probe 7, and the connection pads 6 provided on the lower surface of the ceramic substrate 11 are external for electrical inspection. Electrically connected to the circuit. In order to ensure these electrical connections, pressure is applied in the direction in which the multilayer wiring board is pressed against the semiconductor element. Then, the semiconductor element and the external circuit are electrically connected via the multilayer wiring board, and it is inspected whether or not the semiconductor element can operate normally.

  In this case, the thin-film conductor layer 22 connected to the electrode of the semiconductor element is provided with a fine pattern and a small adjacent interval compared to the connection pad 6 connected to the external circuit. Further, in the thin film wiring layer 12, the closer to the uppermost surface, the thinner the thin film conductor layer 22 is provided at a finer and narrower pitch. As a result, the electrical connection between the electrodes of the fine semiconductor element and the external circuit which is larger than this and which has a wide adjacent interval can be easily performed.

The multilayer wiring board of this embodiment is electrically connected to the wiring layer 2 by a plurality of insulating layers 1 stacked on each other, a wiring layer 2 provided between the plurality of insulating layers 1, and a bonding member 3 made of a metal material. And the width W ₁ of the bonding member 3 is smaller than the width W _{2 of the} via conductor 4 in a longitudinal sectional view. The via conductor 4 is provided in the vertical direction in the insulating layer 2 provided on the wiring layer 2 among the plurality of insulating layers 1. Since the width W ₁ of the bonding member 3 is smaller than the width W ₂ of the via conductor 4 in a longitudinal sectional view, the bonding member 3 having a width smaller than that of the via conductor 4 when a lamination pressure is applied to the multilayer wiring board. Since the force concentrates on the lower end portion of the metal, the adhesion strength between the bonding member 3 and the wiring layer 2 is improved, and the bonding strength between the via conductor and the wiring layer is improved.

(Second Embodiment)
Next, a multilayer wiring board according to a second embodiment of the present invention will be described with reference to FIG.

  The multilayer wiring board according to the second embodiment of the present invention differs from the multilayer wiring board according to the first embodiment described above in that the lower end portion of the bonding member 3 is connected to the wiring layer 2 as in the example shown in FIG. It is a point that is buried in. Since the lower end portion of the joining member 3 and the side surface on the lower end portion side of the joining member 3 and the wiring conductor 21 are joined, when a force is applied from the side direction of the multilayer wiring board, the joining member 3 and the wiring conductor 21 The occurrence of delamination during the period can be reduced.

  A multilayer wiring board in which the lower end portion of the bonding member 3 is embedded in the wiring layer 2 is manufactured as follows. That is, after the joining member 3 is provided by placing a plating method or a plate-like metal member on the lower end portion of the via conductor 4, the thin film wiring layer 12 or the thin film wiring layer 12 and the ceramic substrate 11 are pressurized, What is necessary is just to pressurize the joining member 3. FIG. Since the joining member 3 is in a relatively high density state, the lower end portion of the joining member 3 can be embedded in the wiring layer 2.

  Note that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. For example, in the longitudinal sectional view, the width of the bonding member 3 may gradually decrease from the upper end portion in contact with the via conductor 4 toward the lower end portion in contact with the wiring conductor 21. The force applied to the joining member 3 can be more effectively concentrated at the lower end.

1 ... Insulating layer
11 ... Ceramic substrate
12 ... Thin wiring layer
121 ... resin insulation layer 2 ... wiring layer
21 ... Wiring conductor
22 ... Thin film conductor layer 3 ... Joining member 4 ... Via conductor 5 ... Joining layer
6 ... Connection pad 7 ... Probe

Claims (2)

A plurality of insulating layers stacked on each other;
A wiring layer provided between the plurality of insulating layers;
A via conductor that is provided vertically in an insulating layer provided on the wiring layer among the plurality of insulating layers, and is electrically connected to the wiring layer by a joining member made of a metal material; And
A multilayer wiring board, wherein a width of the joining member is smaller than a width of the via conductor in a longitudinal sectional view.   The multilayer wiring board according to claim 1, wherein a lower end portion of the joining member is embedded in the wiring layer.

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