JP2011222945A - Multilayer wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer wiring board which helps to suppress mechanical breakdown in lead-through conductors, etc. even when a plurality of lead-through conductors are laid one on top of another in a plan view.SOLUTION: A multilayer wiring board 5 comprises a thin-film multilayer section 4 configured with alternately laminated resin insulating layers 1 and thin-film wiring layers 2, with upper and lower thin-film wiring layers 2 electrically connected to each other by a lead-through conductor 3. The lead-through conductor 3 includes those which are formed at positions overlapping one on top of another in a plan view across a plurality of vertically consecutive resin insulating layers 1, and some of plural lead-through conductors 3 (3a, 3b) laid one on top of another in a plan view are made of a metal material containing tin as main constituent while the other are made of a metal material containing copper as main constituent. A lead-through conductor 3a made of a metal material containing tin with low modulus elasticity relieves stresses arising for reasons that a plurality of lead-through conductors 3 are laid one on top of another, thereby helping to suppress occurrence of cracks or the like in the inside or other parts of the lead-through conductors 3.

Description

  The present invention provides a multilayer having thin film multilayer portions in which resin insulating layers and thin film wiring layers are alternately laminated, and upper and lower thin film wiring layers are electrically connected to each other by through conductors penetrating the resin insulating layer in the thickness direction. The present invention relates to a wiring board.

  Conventionally, as a multilayer wiring board for connecting a semiconductor element to a terminal on the upper surface and electrically connecting a connection pad on the lower surface electrically connected to the terminal to an external electric circuit, a plurality of thin film wiring layers and a plurality of wiring layers are provided. There is known a multilayer wiring board in which thin film multilayer portions in which resin insulating layers are alternately laminated are arranged on the upper surface of a substrate such as a ceramic substrate. Such a multilayer wiring board is used, for example, as a so-called probe card board for performing an electrical check of a semiconductor element.

  In such a multilayer wiring board, for example, a metalized wiring layer made of a metal material such as tungsten or a wiring conductor such as a through conductor is arranged on the upper and lower surfaces and inside of an insulating base made of an aluminum oxide sintered body or the like. It is a structured. The thin film wiring layer formed exposed on the upper surface of the thin film multilayer portion functions as a terminal connected to the semiconductor element, and the wiring conductor formed on the lower surface of the ceramic substrate functions as a connection pad for external connection.

  In the thin film multilayer portion, a thin film wiring layer is formed corresponding to a semiconductor element in which electrodes are arranged at a high density. In order to cope with the recent increase in the density of electrodes of a semiconductor element, a further thin film layer is formed. There is a demand for higher density wiring layers. In order to increase the density, it is necessary to further increase the density of the through conductors connecting the thin film wiring layers up and down. In order to increase the density of the through conductors, the through conductors of the respective resin insulation layers are formed so as to overlap each other in a plan view over a plurality of resin insulation layers that are continuous in the vertical direction (so-called stacked vias). ) Has been proposed.

JP 2003-218531 A JP 2006-173333 A

  However, when the through conductors are formed so as to overlap in a plan view across the plurality of resin insulation layers as described above, the coefficient of thermal expansion (the thermal expansion coefficient between a metal material such as copper and the resin insulation layer forming the through conductors ( Since the linear expansion coefficients are different, a large thermal stress is likely to occur between the resin insulating layer and the through conductor due to the difference in thermal expansion coefficient. And there existed a problem that mechanical destruction, such as a crack and a disconnection, was easy to produce in the interface of a penetration conductor and a penetration conductor and a resin insulating layer by this thermal stress. When such a mechanical breakdown occurs, for example, an increase in electrical resistance or reliability of electrical connection between the thin film wiring layer on the upper surface side and the thin film wiring layer on the lower surface side of the thin film multilayer portion. Cause problems such as lowering

The present invention has been completed in view of the above-described problems of the prior art, and its purpose is that the through conductors are formed at positions where they overlap each other in plan view across a plurality of resin insulating layers that are vertically continuous. However, it is possible to effectively suppress the mechanical breakdown at the through conductor or the interface between the through conductor and the resin insulation layer, and it is possible to reduce the size and the reliability of the multilayer wiring board. It is to provide.

  In the multilayer wiring board of the present invention, resin insulating layers and thin film wiring layers are alternately laminated, and the upper and lower thin film wiring layers are electrically connected to each other by through conductors that penetrate the resin insulating layer in the thickness direction. A multilayer wiring board having a thin film multilayer portion, wherein the through conductor includes a plurality of resin insulating layers formed vertically and overlapping with each other in a planar view, and includes a plurality of overlapping in a planar view. A part of the through conductor is made of a metal material mainly composed of tin, and the other is made of a metal material mainly composed of copper.

  In the multilayer wiring board of the present invention, in the above configuration, the through conductors are formed at positions overlapping with each other in plan view over three or more resin insulating layers that are continuous in the vertical direction. What is formed in the said resin insulation layer located in the center part of an up-down direction consists of a metal material which has tin as a main component, and another thing consists of a metal material which has copper as a main component, It is.

  Further, the multilayer wiring board of the present invention has the above-described resin insulating layers above and below the resin insulating layer where one end surface of the through conductors made of a metal material mainly composed of tin is located. Are mutually bonded via a resin adhesive layer having a through hole at a position corresponding to the through conductor, and the through conductors of the upper and lower resin insulation layers are in the through hole of the resin adhesive layer. They are electrically connected to each other by a metal material mainly composed of tin filled in.

  In the multilayer wiring board of the present invention, in the above structure, at least a part of the side surface of the metal material mainly composed of tin filled in the through hole of the resin adhesive layer is curved in a convex shape. It is characterized by this.

  In the multilayer wiring board of the present invention, in the above configuration, a plurality of the through holes filled with the metal material for electrically connecting the plurality of through conductors up and down are arranged in the resin adhesive layer. In addition, the side surface of the metal material has only an intersecting portion located on a side closer to the central portion among portions intersecting with a virtual straight line extending radially from the central portion of the resin adhesive layer toward the outer side in a plan view. It is characterized by being curved in a convex shape or being curved in a convex shape larger than other portions at the intersection.

  According to the multilayer wiring board of the present invention, in the thin film multilayer portion, the through conductors include those formed at positions overlapping each other in a plan view across a plurality of resin insulating layers continuous in the vertical direction. Since some of the through conductors are made of a metal material mainly composed of tin and the other is made of a metal material mainly composed of copper, even in the case of having a so-called stacked via in which the upper and lower through conductors are continuous. The thermal stress generated between the through conductor and the resin insulating layer can be relaxed by a metal material mainly composed of tin having a lower elastic modulus than copper. Therefore, it is possible to suppress the occurrence of mechanical breakdown such as cracks at the through conductor or the interface between the through conductor and the thin film wiring layer. Moreover, since only some of the plurality of through conductors are made of a metal material mainly composed of tin and the other is made of a metal material mainly composed of copper, Electrical resistance can be kept low. For this reason, an increase in electrical resistance as a multilayer wiring board is effectively suppressed.

In the multilayer wiring board of the present invention, in the above configuration, through conductors are formed at positions overlapping with each other in plan view over three or more continuous resin insulating layers in the vertical direction, and the vertical direction of these through conductors If the resin insulation layer located in the central part of the material is made of a metal material mainly composed of tin and the other is composed of a metal material mainly composed of copper, the thermal stress in the through conductor Can be made more effective.

  That is, in the thin film multi-layer part, when the through conductors are formed at positions overlapping with each other in plan view over three or more continuous resin insulating layers in the upper and lower directions, the resin located in the central portion in the vertical direction where stress is easily concentrated Since the elastic modulus can be kept low in the through conductor of the insulating layer, the thermal stress can be alleviated more effectively.

  Further, in the multilayer wiring board of the present invention, in the above configuration, the upper and lower resin insulation layers are arranged between the resin insulation layers where one end face of the through conductor is made of a metal material mainly composed of tin, Bonded to each other through a resin adhesive layer having a through hole at a position corresponding to the through conductor, and the through conductors of the upper and lower resin insulation layers are mainly composed of tin filled in the through hole of the resin adhesive layer. When the metal materials are electrically connected to each other, it is possible to provide a multilayer wiring board that is effective in alleviating thermal stress in the through conductor and also effective in improving productivity.

That is, in this case, a plurality of resin insulation layers having penetrating conductors are manufactured by dividing them into upper and lower parts with a portion where the penetrating conductors are formed of a metal material mainly composed of tin, and these are formed as resin adhesive layers. Thus, it is easy to improve the productivity of the thin-film multilayer part, and it is effective in improving the productivity as a multilayer wiring board. In this case, since the melting point of the metal material mainly composed of tin (melting point: about 232 ° C) is relatively low, the metal material is melted and filled in the through hole of the resin adhesive layer in order to connect the upper and lower through conductors. It is also easy to make it. Moreover, for example, tin-silver solder can be used as the metal material containing tin as a main component, and bonding to a through conductor made of a metal material containing copper as a main component is easy.

  Further, in the multilayer wiring board of the present invention, in the above configuration, when at least a part of the side surface of the metal material mainly composed of tin filled in the through hole of the resin adhesive layer is curved in a convex shape, The reliability of connection between the metal material and the thin film wiring layer can be further improved.

  That is, in this case, the thermal stress in the lateral direction (that is, the horizontal direction along the interface between the resin insulating layer and the resin adhesive layer) caused by the difference in coefficient of thermal expansion between the resin insulating layer and the resin adhesive layer. Acting as a shear stress on the metal material in the through hole can be suppressed. This is because, when the stress acts on the metal material, it is dispersed in the vertical and diagonal directions along the curved side surface, and the component acting as a shear stress in the lateral direction is reduced.

  Therefore, mechanical destruction such as cracks between the metal material and the through conductor (or the thin film wiring layer interposed between the metal material and the through conductor) due to stress is more reliably suppressed, and the metal material and The connection reliability with the through conductor and the thin film wiring layer can be further improved.

  In the multilayer wiring board of the present invention, in the above configuration, a plurality of through holes filled with a metal material for electrically connecting a plurality of through conductors up and down are arranged in the resin adhesive layer. Only the intersection located on the side closer to the center of the portion intersecting with the virtual straight line extending radially from the center of the resin adhesive layer toward the outer side in plan view is curved in a convex shape. Alternatively, when the intersection is curved in a convex shape larger than other portions, thermal stress acting as shear stress on each metal material of the resin adhesive layer arranged corresponding to the plurality of through conductors is applied. It can be mitigated more effectively.

That is, in this case, in the resin adhesive layer, a large thermal stress tends to act on the metal material in a direction along a virtual straight line extending radially from the center toward the outer side. Therefore, for these metal materials, a larger thermal stress (shear stress) tends to act at a portion where the imaginary straight line intersects. Disconnection between the metal material and the through conductor or the thin film wiring layer is likely to occur due to stress at the intersection located on the side close to.

  On the other hand, in the case where the above configuration is provided, in the metal material, the side surface on which the thermal stress tends to concentrate is greatly curved, so that the thermal stress is dispersed and the effect of relaxing the stress can be enhanced. . Therefore, in a configuration in which a plurality of metal materials are arranged, it is possible to effectively improve the connection reliability between the metal material and the through conductor or the thin-film wiring layer while suppressing the range of curvature of the side surface of the metal material to be small. .

  In other words, in the above configuration, only the intersecting portion located nearer to the central portion of the portion intersecting with the virtual straight line of the metal material is curved in a convex shape or larger in this portion than the other portions. If it is curved (protruding outward), the stress can be relieved while keeping the curved portion of the metal material side, ie, the area protruding outward, small, so the metal material (and penetration) This is advantageous in increasing the density of the conductor).

It is sectional drawing which shows an example of embodiment of the multilayer wiring board of this invention. FIG. 2 is an enlarged cross-sectional view of a main part showing an enlarged main part of the multilayer wiring board shown in FIG. 1. It is a principal part expanded sectional view which expands and shows the principal part in the other example of embodiment of the multilayer wiring board of this invention. (A)-(c) is the principal part expanded sectional view which expands and shows the principal part in the other example of embodiment of the multilayer wiring board of this invention, respectively. (A) is the top view (perspective view) which planarly viewed the part of the resin contact bonding layer in the other example of embodiment of the multilayer wiring board of this invention, (b) expanded the principal part of (a). FIG. (A) And (b) is a principal part expanded sectional view which expands and shows the principal part in the other example of embodiment of the multilayer wiring board of this invention, respectively.

  A multilayer wiring board according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing an example of an embodiment of a multilayer wiring board according to the present invention, and FIG. 2 is an enlarged cross-sectional view showing a main part of the multilayer wiring board shown in FIG. 1 and 2, 1 is a resin insulating layer, 2 is a thin film wiring layer, 3 is a through conductor, and 4 is a thin film multilayer portion. A thin film multilayer portion 4 is constituted by the resin insulating layer 1, the thin film wiring layer 2 and the through conductor 3, and the thin film multilayer portion 4 is laminated on the upper surface of the ceramic substrate 6 to constitute the multilayer wiring substrate 5.

  The resin insulating layer 1 is, for example, a rectangular shape such as a rectangular shape or a square shape, or a circular shape, and is formed in a layer shape having a thickness of about 25 μm. In the example shown in FIG. 1, the plurality of resin insulating layers 1 have the same outer dimensions and shapes in plan view, and are laminated so that the outer surface of the multilayer wiring board 5 is not uneven. The plurality of laminated resin insulation layers 1 serve as an insulating base portion (not indicated) in the thin film multilayer portion 4. For example, an electronic component (not shown) such as a semiconductor element is mounted on the top surface, and the bottom surface Is mounted on a highly rigid substrate such as the ceramic substrate 6.

  These resin insulation layers 1 are made of, for example, a resin material such as an epoxy resin, a polyimide resin, a polyamideimide resin, a polyetherimide resin, or a liquid crystal polymer.

The through conductor 3 and the thin film wiring layer 2 penetrating the resin insulating layer 1 in the thickness direction electrically connect electrodes such as semiconductor elements mounted on the multilayer wiring board 5 to an external electric circuit (not shown) such as a printed circuit board. This is a portion that becomes a conductive path for connection. For example, when a semiconductor element is mounted on the center of the upper surface of the thin film multilayer portion 4 and the electrode is electrically connected to the thin film wiring layer 2 exposed on the uppermost surface of the thin film multilayer portion 4 via solder, a probe, or the like. The electrodes of the semiconductor element are electrically connected to the lowermost thin film wiring layer 2 of the thin film multilayer portion 4 through the thin film wiring layer 2 and the through conductor 3. Then, if the thin-film wiring layer 2 on the lowermost surface of the thin-film multilayer part 4 is electrically connected to an external electric circuit through a wiring conductor 7 previously formed on the ceramic substrate 6, for example, the electrode of the semiconductor element And an external electric circuit are electrically connected.

  In the example shown in FIG. 1, the ceramic substrate 6 is also formed in the same shape and dimensions as the thin film multilayer portion 4 in plan view. In other words, the multilayer wiring board 5 has, for example, a square plate shape or a disk shape as a whole, and an upper surface is mounted with an electronic component such as a semiconductor element for mounting and electrical checking (the semiconductor element is electrically connected to the multilayer wiring board 5). It is also used as a part for mounting mechanically to form a semiconductor device, or for temporary placement for electrical checking of semiconductor elements. Examples of semiconductor elements include semiconductor integrated circuit elements such as ICs and LSIs, and micromachines (so-called MEMS elements) in which a minute electromechanical mechanism is formed on the surface of a semiconductor substrate.

  The thin film wiring layer 2 is 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 2 is formed by depositing the above metal material on the surface such as the upper surface of the resin insulating layer 1 by a sputtering method, a vapor deposition method, a plating method, or the like, and trimming processing such as masking or etching as necessary. Can be applied to the surface of the resin insulating layer 1 in a predetermined pattern.

The through conductor 3 is, for example, a through hole penetrating in a thickness direction in a part of the resin insulating layer 1 by drilling such as laser processing using a CO ₂ laser or YAG laser, RIE (reactive ion etching), or etching using a solvent. (No symbol) is formed, and a conductive material to be the through conductor 3 is filled in the through hole by a method such as sputtering, vapor deposition, plating, or filling of a conductive paste.

  Such a through conductor 3 may also be made of a metal material such as copper, silver, palladium, gold, platinum, aluminum, chromium, nickel, cobalt, titanium, tungsten, or an alloy material of these metal materials. However, with respect to the through conductors 3 that are formed at positions that overlap each other in a plan view across a plurality of resin insulating layers 1 that are continuous vertically, a part of the plurality of through conductors 3 that overlap in a plan view is tin. It is necessary to be made of a metal material having a main component and the other being made of a metal material having copper as a main component.

  That is, in the multilayer wiring board 5 of the present invention, the through conductor 3 of the thin film multilayer portion 4 includes a plurality of resin insulating layers 1 that are vertically continuous and are formed at positions overlapping each other in plan view. A part of the plurality of through conductors 3 overlapping in view is a through conductor 3a made of a metal material mainly composed of tin, and the other is a through conductor 3b made of a metal material mainly composed of copper.

In this way, the through conductors 3 are overlapped with each other in a plan view over the plurality of resin insulating layers 1 that are continuous in the vertical direction, that is, the plurality of through conductors 3 are arranged vertically (if necessary, the thin film wiring layer 2 is disposed). In the thin film multi-layer part 4 having a so-called stacked via that is continuous), the thermal stress generated between the through conductor 3 and the resin insulating layer 1 is a metal material mainly composed of tin having a lower elastic modulus than copper. The through conductor 3a can be effectively relaxed. Therefore, the through conductor 3 (particularly, the end portion of the inside of the through conductor 3 that is in contact with the thin film wiring layer 2 in particular)
In addition, the occurrence of mechanical breakdown such as cracks at the interface between the through conductor 3 and the thin film wiring layer 2 is suppressed. Further, the through conductor 3b made of a metal material whose main component is copper having a low electric resistance (the resistivity of tin is about 11.5 Ω · m, whereas the resistivity of copper is about 1.7 Ω · cm). Thus, the electrical resistance of the entire through conductor 3 can be kept low.

  Further, by having the through conductors 3a and 3b formed at such overlapping positions in plan view, the area of the thin film multilayer portion 4 and the multilayer wiring board 5 as a whole can be kept small.

In this case, the Young's modulus of copper is approximately 129.8 GPa, whereas the Young's modulus of tin is approximately 49.9 GPa.
The deformation amount is about 2.6 times larger for tin than for copper. for that reason,
The above stress can be effectively relaxed.

  In addition, it is preferable that the metal material which has copper as a main component contains about 20 mass% or more of copper, in order to suppress the electrical resistance in the through-conductor 3 effectively low. In the metal material mainly composed of copper, examples of the material added to copper include titanium, chromium, nickel, and cobalt.

Moreover, it is preferable that the metal material containing tin as a main component contains tin in an amount of about 90% or more in order to effectively relieve stress in the through conductor 3. In the metal material mainly composed of tin, silver, copper, bismuth, indium or the like can be used as the metal material added to tin. As tin added with such a metal material, for example, a material that becomes a low melting point brazing material (so-called lead-free solder or the like) can be used. For example, when about 5% by mass of silver is added to tin, effects such as prevention of whisker generation can be obtained as compared with the case where tin is 100% by mass.

  The through conductor 3 preferably has a larger cross-sectional area (cross-section in a direction perpendicular to the direction of current flow) in order to keep electric resistance low, and the cross-section is small in order to keep the outer dimensions of the multilayer wiring part 4 small. The more preferable. Further, among the through-hole conductors 3 which are formed at positions where they overlap each other in plan view over a plurality of resin insulating layers 1 which are continuous in the vertical direction, stress is relieved and cracks are suppressed as described above. For this purpose, a circular shape is preferable.

  The transverse cross section of such a through conductor 3 may be appropriately set in consideration of the above requirements. For example, the length of the through conductor 3 (the dimension in the thickness direction of the resin insulating layer 1) is about 15 to 30 μm. In this case, a circular shape with a diameter of about 30 to 50 μm, an elliptical shape with a major axis length of about 30 to 50 μm and a minor axis length of about 30 to 50 μm may be used.

  In addition, about the penetration conductors 3a and 3b formed in the position which mutually overlaps by planar view over the several resin insulation layer 1 continuous up and down, in FIG. 1, in the resin insulation layer 1 of three layers, each penetration conductor 3a, In the example, 3b is formed in a position overlapping with each other in plan view, but in each of the four or more resin insulating layers 1, the through conductors 3a and 3b are formed in positions overlapping each other in plan view. Also good. Even in such a case, all of the upper and lower through conductors 3 that overlap each other in plan view (at least one through conductor 3 of the resin insulating layer 1) are made of a metal material mainly composed of tin, as long as they are all. Compared to the case where the through conductor 3 is made of a metal material 3b mainly composed of copper, the stress can be relaxed and the occurrence of cracks in the through conductor 3 and the like can be reduced.

However, in the thin film multilayer portion 4, in the portion where the through conductor 3 is formed at a position overlapping in a plan view over a plurality of resin insulating layers 1 that are continuous in the vertical direction, the resin insulating layer 1 positioned in the central portion in the vertical direction is used. It is preferable to arrange the through conductor 3a made of a metal material mainly composed of tin. This is because when the upper and lower penetrating conductors 3 are formed so as to overlap with each other in plan view, thermal stress from both the upper and lower directions concentrates on the penetrating conductor 3 of the resin insulating layer 1 located at the center in the vertical direction. The stress acting on the through conductor 3 of the resin insulating layer 1 located in the center portion tends to increase, and the stress can be more effectively relieved in this portion. This is because it is effective in suppressing mechanical breakage such as cracks at the interface with the layer 2.

  That is, in the multilayer wiring board 5 of the present invention, the through conductors 3 (3a, 3b) are formed at positions where they overlap each other in a plan view over the three or more continuous resin insulating layers 1 in the vertical direction. When the one formed in the resin insulating layer 1 located in the central portion in the vertical direction is made of a metal material mainly containing tin, and the other is made of a metal material mainly containing copper The thermal stress in the through conductor 3 can be more effectively reduced.

  Then, when the respective through conductors 3 overlap each other in plan view over the three or more layers of resin insulating layers 1 that are continuous in the vertical direction, the main resin insulating layer 1 in which stress is likely to concentrate is mainly composed of tin. Since the elastic modulus can be kept low in the through conductor 3a made of a metallic material, the thermal stress due to the difference in thermal expansion coefficient between the through conductor 3 and the resin insulating layer 1 can be more effectively performed. it can.

  In this case, when the thickness of the resin insulating layer 1 is about 15 to 30 μm which can be easily formed by the resin material described above, the length of each through conductor 3 is also about 15 to 30 μm. In such a case, with respect to the resin insulating layer 1 that is vertically continuous, up to about five layers, even if the through conductors 3 are formed at positions overlapping each other in plan view, the center in the vertical direction If the through conductor 3a made of a metal material containing tin as a main component is formed in the single resin insulating layer 1 located in the portion, the thermal stress can be alleviated more effectively.

  The multilayer wiring board 5 having the thin film multilayer portion 4 as described above can be manufactured, for example, as follows.

  First, a substrate having relatively high rigidity such as a ceramic substrate 6 is prepared. This substrate is used for forming a multilayer wiring board 5 having high rigidity by depositing a thin film multilayer portion 4 having low rigidity on the upper surface thereof. The ceramic substrate 6 is made of, for example, an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body, a glass ceramic sintered body, crystallized glass in which crystal components are precipitated in a glass base material, mica, titanium, or the like. It is made of a ceramic material such as a ceramic material (so-called machinable ceramics), which is made of a microcrystalline sintered body such as aluminum oxide, and can be machined substantially as accurately as a metal material.

  If the ceramic substrate 6 is made of, for example, an aluminum oxide sintered body, it can be manufactured as follows. That is, 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. After that, the ceramic green sheet can be made into an appropriate shape and size by cutting or punching and fired at a temperature of about 1300 to 1500 ° C.

The ceramic substrate 6 is covered with a wiring conductor 7 by a metallizing method or a plating method using a metal material such as tungsten, molybdenum, manganese, copper, silver, palladium, gold, or platinum, if necessary. Let me wear it. If the wiring conductor 7 is made of tungsten, for example, a paste of tungsten is applied or filled on the surface of the ceramic green sheet to be the ceramic substrate 6 or the inside of a through-hole formed in advance, and the ceramic green sheet It can be deposited by co-firing.

Next, an uncured product of the above resin material (polyimide resin, polyamideimide resin, polyetherimide resin, liquid crystal polymer, etc.) is applied to the upper surface of the ceramic substrate 6 in a layered form and cured to deposit the resin insulation layer 1 And through-hole processing such as laser processing using a CO ₂ laser or YAG laser, RIE (reactive ion etching), or etching using a solvent so that a part of the resin insulating layer 1 is penetrated in the thickness direction. Form. Thereafter, the above metal material (copper, silver, palladium, gold, platinum, aluminum, chromium, nickel, cobalt, titanium, tungsten) is applied to the upper surface of the resin insulating layer 1 and the inside of the through hole by sputtering, vapor deposition or plating. The thin film wiring layer 2 and the through conductor 3 are formed by depositing or filling in a pattern by a method such as the above. At this time, among the through conductors 3 that are formed at positions that overlap each other in a plan view across a plurality of resin insulating layers 1 that are continuous in the vertical direction, a part of the through conductors 3 must be formed of a metal material mainly composed of tin. Others need to be formed of a metal material mainly composed of copper.

  The through conductor 3a made of a metal material mainly composed of tin can be heated by filling a through hole of the resin insulating layer 1 with, for example, a paste of a tin-silver low melting point brazing material (so-called lead-free solder). Can be formed.

  In addition, the through conductor 3b made of a metal material mainly composed of copper, for example, is formed by depositing a thin film metal layer such as titanium on the inner surface of the resin insulating layer 1 by a sputtering method, and plating on the thin film metal layer. It can be formed by depositing copper by the method and filling the through hole with a copper plating layer.

  And if this process of forming the resin insulation layer 1, the thin film wiring layer 2 and the through conductor 3 is repeated, the thin film multilayer portion 4 is disposed on the upper surface of the ceramic substrate 6, and in the thin film multilayer portion 4, a plurality of continuous vertical layers are provided. Manufacturing a multilayer wiring board 5 in which a through conductor 3a made of a metal material mainly composed of tin and a through conductor 3b mainly composed of copper are formed at positions overlapping with each other in a plan view over the resin insulating layer 1. Can do.

  In the multilayer wiring board 5 of the present invention, in any of the above-described configurations, for example, as shown in FIG. 3, the resin in which one end surface of the through conductor 3 made of a metal material mainly composed of tin is located. Between the insulating layers 1, the upper and lower resin insulating layers 1 are bonded to each other via a resin adhesive layer 8 having a through hole (not indicated) at a position corresponding to the through conductor 3 (3a, 3b). When the through conductors 3 (3a, 3b) of the upper and lower resin insulation layers 1 are electrically connected to each other by a metal material 9 whose main component is tin filled in the through holes of the resin adhesive layer 8 Is effective in improving the productivity of the multilayer wiring board 5.

  That is, a plurality of resin insulation layers 1 having penetrating conductors 3 (3a, 3b) are formed separately in the upper and lower portions at the portion where the penetrating conductor 3a is formed of a metal material mainly composed of tin, and these are formed as the resin adhesive layer 8. Since the multilayer wiring board 5 can be produced by bonding with the above, it is easy to increase the productivity as the multilayer wiring board 5. In other words, instead of sequentially laminating the resin insulation layer 1 and the like on the upper surface of the ceramic substrate 6 for example, the thin film multilayer portion 4 can be manufactured in parallel by dividing the resin insulation layer 1 and the like into a plurality of blocks. This can increase productivity.

Further, since the melting point of the metal material 9 mainly composed of tin (melting point: about 232 ° C.) is relatively low, the metal material 9 in the through hole of the resin adhesive layer 8 is connected to connect the upper and lower through conductors 3 (3a, 3b). It is also easy to melt and fill the metal material 9. In this case, for example, tin-silver solder can be used as the metal material 9 containing tin as a main component (hereinafter sometimes simply referred to as metal material 9), and the through conductor 3b made of a metal material containing copper as a main component. Bonding to is easy.

  As the resin adhesive layer 8, the same resin material as that of the resin insulating layer 1 can be used, but one having a lower curing temperature is preferably used. This is due to the suppression of deformation of the metal material 9 when the resin adhesive layer 8 is thermoset with the metal material 9 mainly composed of tin disposed in the resin adhesive layer 8, workability, and the like. . In this case, the coefficient of thermal expansion differs between the resin insulating layer 1 and the resin adhesive layer 8, and thermal stress may occur. Further, the through hole of the resin adhesive layer 8 can be formed by a method such as laser processing, RIE, etching with a solvent, and the like, as in the case of the resin insulating layer 1.

  The metal material 9 mainly composed of tin filled in the resin adhesive layer 8 may be the same as the through conductor 3a mainly composed of tin. In this case, for example, when filling the through hole of the resin insulating layer 1 with a metal material (a low melting point brazing paste or the like) containing tin as a main component and serving as the through conductor 3a, If the protruding metal material is filled into the through-holes of the resin adhesive layer 8 with the amount protruding from the upper end of the resin, the metal material can be easily filled into the through-holes of the resin adhesive layer 8. Therefore, the productivity of the multilayer wiring board 5 can be further increased.

  Further, in this case, for example, as shown in FIG. 3, the opening in the connecting portion of the upper and lower through holes (the through hole of the resin insulating layer 1 and the through hole of the resin adhesive layer 8) is made more than the other portions. It is preferable to make it wide in order to more easily fill the paste with a low melting point brazing material. In this case, it can be considered that a continuous through conductor (no symbol) made of a metal material mainly composed of tin is formed from the resin adhesive layer 8 to the resin insulating layer 1 in contact therewith. . The upper and lower through conductors 3b made of a metal material mainly composed of copper are electrically connected to each other through the continuous through conductor.

  It should be noted that the electrical connection between the metal material 9 mainly composed of tin of the resin adhesive layer 8 and the through conductor 3 is not necessarily performed by direct connection to each other, and the thin film wiring layer 2 is interposed therebetween. May be performed. For example, in the example shown in FIG. 3, the upper end surface of the metal material 9 is directly connected to the thin film wiring layer 2 and is electrically connected to the upper through conductor 3 (3b) via the thin film wiring layer 2. Yes.

  In the multilayer wiring board 5 of the present invention, the upper and lower resin insulation layers 1 are bonded to each other via a resin adhesive layer 8, and the through conductors 3 of the upper and lower resin insulation layers 1 are bonded to each other by a metal material 9. In the above electrically connected configuration, when at least a part of the side surface of the metal material 9 is curved in a convex shape, the connection reliability between the metal material 9 and the through conductor 3 and the thin film wiring layer 2 is improved. Can be improved. This will be described below as another embodiment. In order to bend the side surface of the metal material 9 as described above, the inner side surface of the through hole of the resin adhesive layer 8 filled with the metal material 9 needs to be similarly curved.

  Another example of the embodiment of the multilayer wiring board 5 of the present invention is shown in FIG. 4A to 4C are main part cross-sectional views showing main parts in other examples of the embodiment of the multilayer wiring board 5 of the present invention. 4, parts similar to those in FIGS. 1 and 3 are given the same reference numerals.

  As shown in FIG. 4A, when a part of the side surface of the metal material 9 mainly composed of tin filled in the resin adhesive layer 8 is curved in a convex shape, the resin adhesive layer 8 and It can suppress that the thermal stress which arises between the metal materials 9 acts as a shear stress with respect to the metal material 9 which has as a main component the tin with which the through-hole of the resin contact bonding layer 8 was filled. This is because when the stress acts on the metal material 9, it is dispersed in an oblique direction along the curved side surface, and the component acting as a shear stress is suppressed to be small.

  Therefore, cracks between the metal material 9 and the thin film wiring layer 2 due to stress can be more reliably suppressed, and the connection reliability between the metal material 9 and the thin film wiring layer 2 can be further improved.

  In addition, the example shown to Fig.4 (a) is an example in which the lower side was curving convexly among the side surfaces of the inclined metal material 9 as shown in FIG. In this example, the portion of the curved side surface that protrudes to the outermost side (the most protruding portion) is in the middle of the side surface of the metal material 9 in the vertical direction, and again extends toward the center of the metal material 9 from the most protruding portion to the lower end. bent. That is, a part of the side surface in the vertical direction protrudes outward to form a convex portion.

  In the case where the metal material 9 has the above-described shape, the components that are compressed in the vertical direction with respect to the metal material 9 out of the stress dispersed in the oblique direction cancel each other up and down the convex portion. The action in the direction of peeling the thin film wiring layer 2 is suppressed. Therefore, it is effective in further improving the connection reliability between the metal material 9 and the thin film wiring layer 2.

  As shown in FIG. 4B, when the entire side surface of the metal material 9 is curved in a convex shape, from the upper end to the lower end of the side surface of the metal material 9 (that is, in a wider range of the side surface). Stress can be dispersed. Therefore, also in this case, the connection reliability between the metal material 9 and the thin film wiring layer 2 can be further improved.

  In the example shown in FIG. 4B, the bending method of the curved side surface of the metal material 9 (the radius of curvature of the arc-shaped line corresponding to the side surface in the longitudinal section of the metal material 9) changes in the middle, and in the lower part It is curved more than the top (projects more outward). In such a case, in the structure in which the side surface of the metal material 9 is curved from the upper end to the lower end, the effect (dispersion) when only a part of the side surface is curved as in the example shown in FIG. It is also possible to obtain a certain degree of suppression of the stress acting on the metal material 9 and the thin film wiring layer 2 in the direction of peeling off.

  The example shown in FIG. 4C is an example in which the lower side of the side surface of the metal material 9 is curved in a convex shape, and the most protruding portion is located at the lower end. In other words, the opening diameter of the through hole filled with the metal material 9 of the resin adhesive layer 8 is the largest at the lower end.

  As shown in this example, the upper and lower through-holes (through holes in the resin insulation layer 1 and through-holes in the resin adhesive layer 8) are connected to each other with a wider opening than the other parts. It is preferable in order to more easily fill the through holes such as paste of the low melting point brazing material to be the material 9.

  In order to curve at least a part of the side surface of the metal material 9 in a convex shape, for example, the following may be performed.

  That is, first, through holes as shown in FIG. 3 are formed in the resin adhesive layer 8 which is uncured and can be plastically deformed to some extent, as in the case of the resin insulating layer 1 described above, laser processing, RIE, etching with a solvent. It is formed by drilling such as.

  Thereafter, for example, as described above, a metal material (low melting point brazing paste) that becomes the through conductor 3 (3a) is protruded from the upper end of the through hole of the resin insulating layer 1, and this protruding metal material is removed. It can be formed by filling the through-holes of the resin adhesive layer 8 and then curing the uncured resin adhesive layer 8. When the protruding metal material is filled into the through-holes of the resin adhesive layer 8, the resin adhesive layer 8 is plastically deformed (penetrated) by increasing the volume of the metal material 9 relative to the volume of the through-holes. The hole swells laterally), and the inner surface of the through hole is curved. In response to this, the side surface of the metal material 9 is curved.

In addition, as shown in FIG. 5, for example, the multilayer wiring board 5 of the present invention has a plurality of through holes filled with a metal material 9 electrically connecting the plurality of through conductors 3 in the vertical direction. When disposed, the side surface of the material 9 is an intersection located on the side closer to the center portion of the portion intersecting with a virtual straight line L extending radially from the center of the resin insulating layer 1 toward the outer side in a plan view. If only the portion is curved in a convex shape or is curved larger than the other portion at this intersection, each metal of the resin adhesive layer 8 disposed corresponding to the plurality of through conductors 3 Thermal stress acting as shear stress on the material 9 can be further relaxed. FIG. 5A is a plan view (perspective view) of a portion of the resin adhesive layer 8 in another example of the embodiment of the multilayer wiring board 5 according to the present invention, and FIG. It is a principal part enlarged plan view which expands and shows the principal part of Fig.5 (a). 5, parts similar to those in FIGS. 1 and 3 are denoted by the same reference numerals.

  An example of the principal part of the cross section in this structure is shown in FIG. FIGS. 6A and 6B are cross-sectional views showing main parts of other examples of the embodiment of the multilayer wiring board 5 of the present invention. In FIG. 6, the same parts as those in FIGS. 1 and 3 are denoted by the same reference numerals.

  In the example shown in FIG. 6A, the side surface of the metal material 9 is close to the central portion of a portion intersecting with a virtual straight line L extending radially from the center of the resin insulating layer 1 toward the outer side in a plan view. It is curved more greatly than the other part at the intersection located on the side. In this case, the thermal stress in the metal material 9 can be further relaxed in the multilayer wiring board 5 in which the plurality of metal materials 9 are arranged on the resin adhesive layer 8.

  That is, in the metal material 9, a part of the side surface where the thermal stress tends to act more greatly (intersection near the central portion intersecting with the virtual straight line L) is curved, so that the thermal stress increases and decreases. It is more effectively dispersed depending on the direction (oblique direction), and the relaxation effect can be enhanced. Therefore, in the above configuration, the connection reliability between the metal material 9 and the through conductor 3 or the thin film wiring layer 2 can be effectively improved.

  Further, as shown in FIG. 6B, the intersection located on the side closer to the central portion of the portion intersecting with the virtual straight line L extending radially from the center of the resin insulating layer 1 toward the outer side in a plan view. When only the portion is curved in a convex shape, the shear stress acting on the interface between the metal material 9 and the thin-film wiring layer 2 is more effectively suppressed while suppressing the range of the metal material 9 to be curved in a convex shape. Can be reduced.

  In other words, in the above configuration, only the intersecting portion located on the side closer to the center of the portion intersecting the virtual straight line L of the metal material 9 is curved in a convex shape, or in this portion than the other portions. Is larger, the stress can be relaxed while suppressing the curved portion of the side surface of the metal material 9, that is, the range protruding outward, so that the density of the metal material 9 (and the through conductor 3) can be increased. This is advantageous.

(Example 1)
On the top surface of the ceramic substrate made of an aluminum oxide sintered body, 10 layers of resin insulating layers made of epoxy resin having a thickness of about 20 μm and thin film wiring layers made of copper having a thickness of about 10 μm are alternately laminated. The effect of the multilayer wiring board of the present invention was confirmed using a multilayer wiring board in which a through conductor having a diameter of about 400 μm was formed in the resin insulating layer and the upper and lower thin film wiring layers were electrically connected to each other.

A through conductor is formed at a position overlapping with each other in a plan view over three resin insulating layers that are continuous from the top to the bottom of the third to fifth layers of the resin insulating layer, and the center in the vertical direction of the three layers of through conductors 1 (the fourth layer from the top) was formed of a metal material containing 95% by mass of tin as a main component and 5% by mass of silver. The other two through conductors were made of a metal material containing about 99% by mass of copper as a main component and containing titanium and nickel. The through conductors other than these three layers of through conductors were also formed of the same metal material mainly composed of copper as described above.

  In addition, as a comparative example, a multilayer wiring board according to the prior art manufactured in the same manner as the multilayer wiring board of the above example except that all through conductors are formed of the same metal material mainly composed of copper as described above. Got ready.

  In addition, the ceramic board | substrate which formed the wiring conductor by the metallized conductor which consists of tungsten on the surface and the inside of the 1st ceramic board which consists of an aluminum oxide sintered body and is 1 mm in thickness was used.

  For the multilayer wiring boards of these examples and comparative examples, after performing a temperature cycle test as an acceleration test for 500 cycles at + 125 ° C. to −55 ° C., the inside of the through conductor and the boundary between the through conductor and the thin film wiring layer The presence or absence of cracks and disconnections was examined by measuring resistance variation with a digital multimeter using a daisy chain sample in which a plurality of through conductors were connected in series. For samples in which an abnormality such as fluctuation (increase in resistance) was observed in the resistance value, the cross-section of the through conductor portion was observed to check for cracks and the like.

As a result, in the multilayer wiring board of the example, the resistance fluctuation exceeding 20% (increase in electric resistance) and the occurrence of disconnection were not observed, whereas in the multilayer wiring board of the comparative example, the disconnection occurred in 6 out of 20 Occurrence was observed, and resistance variation exceeding 20% was observed in 9 out of 20 pieces. As described above, in the multilayer wiring board of the present invention, even when the through conductors are formed so as to overlap in a plan view over a plurality of resin insulation layers, the machine is formed on the interface between the through conductors or the through conductors and the resin insulation layer. It has been confirmed that it is possible to effectively suppress the occurrence of mechanical destruction, and to provide a multilayer wiring board that can be easily downsized and highly reliable.

(Example 2)
In Example 1, a resin adhesive layer is interposed between the third and fourth layers from the top of the resin insulating layer, and contains 95% by mass of tin as a main component and 5% by mass of silver. The material is disposed so as to penetrate the resin adhesive layer, and the through conductor mainly composed of copper of the third layer and the through conductor mainly composed of tin of the fourth layer are electrically connected through the metal material. A part of the side surface of the metal material mainly composed of tin was curved in a convex shape. The shape of the curve was the same as in the example shown in FIG. A multilayer wiring board of Example 2 was prepared in the same manner as Example 1 except for this. The multilayer wiring board of the comparative example was prepared in the same manner as in Example 1.

For these multilayer wiring boards of Example 2 and Comparative Example, after performing a temperature cycle test as an accelerated test for 1000 cycles at + 125 ° C. to −55 ° C., the inside of the through conductor and the boundary between the through conductor and the thin film wiring layer The presence or absence of cracks and breaks in the wire was examined by measuring resistance variation with a digital multimeter using a daisy chain sample in which a plurality of through conductors were connected in series. For samples in which an abnormality such as fluctuation (increase in resistance) was observed in the resistance value, the cross-section of the through conductor portion was observed to check for cracks and the like.

As a result, in the multilayer wiring board of the example, the resistance fluctuation exceeding 20% (increase in electric resistance) and the occurrence of the disconnection were not seen, whereas in the multilayer wiring board of the comparative example, the disconnection occurred in 11 out of 20 Occurrence was observed, and resistance variation exceeding 20% was observed in 9 out of 20 pieces.

  In other words, in the multilayer wiring board of Example 2, in the configuration in which the resin adhesive layer is interposed between the resin insulating layers (that is, thermal stress is likely to occur), the number of temperature cycles (that is, the number of times the thermal stress is applied). ), The connection between the metal material and the through conductor could be secured.

  As described above, it was confirmed that the effect of improving the reliability can be obtained by curving at least part of the side surface of the metal material.

DESCRIPTION OF SYMBOLS 1 ... Resin insulation layer 2 ... Thin film wiring layer 3 ... Through-conductor 4 ... Thin film multilayer part 5 ... Multi-layer wiring board 6 ... Ceramic substrate 7 ... Wiring conductor 8 ... Resin adhesive layer 9... Metal material mainly composed of tin

Claims (5)

A multilayer wiring board having thin film multilayer portions in which resin insulating layers and thin film wiring layers are alternately laminated, and the upper and lower thin film wiring layers are electrically connected to each other by through conductors penetrating the resin insulating layer in the thickness direction. Because
The penetrating conductor includes a plurality of the resin insulating layers that are vertically continuous with each other so as to overlap each other in plan view, and a part of the plurality of penetrating conductors that overlap in plan view mainly includes tin. A multilayer wiring board comprising a metal material as a component and the other being a metal material mainly composed of copper. The through conductors are formed at positions where they overlap each other in plan view over three or more resin insulating layers that are continuous in the vertical direction, and are formed in the resin insulating layer located in the central portion in the vertical direction of these through conductors. 2. The multilayer wiring board according to claim 1, wherein the one made of a metal material mainly composed of tin and the other composed of a metal material mainly composed of copper. Among the through conductors, the upper and lower resin insulating layers have through holes at positions corresponding to the through conductors between the resin insulating layers where one end face of the metal material mainly composed of tin is located. The through conductors of the upper and lower resin insulation layers are bonded to each other through a metal material mainly composed of tin filled in the through holes of the resin adhesive layer. The multilayer wiring board according to claim 1, wherein the multilayer wiring board is electrically connected.   4. The multilayer wiring board according to claim 3, wherein at least a part of a side surface of the metal material mainly composed of tin filled in the through hole of the resin adhesive layer is curved in a convex shape. 5. .   A plurality of the through holes filled with the metal material for electrically connecting the plurality of through conductors up and down are disposed in the resin adhesive layer, and the side surface of the metal material is the resin in a plan view. Of the portions intersecting with a virtual straight line extending radially from the center of the adhesive layer toward the outer side, only the intersection located on the side closer to the center is curved in a convex shape, or otherwise at the intersection The multilayer wiring board according to claim 4, wherein the multilayer wiring board is curved in a convex shape larger than the portion.

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