JP2015130425A - Wiring board and electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring board in which the characteristics and reliability of an electronic component mounted thereon are improved, and to provide an electronic device.SOLUTION: A wiring board 1 of the invention includes: a mounting metal layer 3 which has an insulation base material 2 having a recessed part 2a and an outer wall surface 2b and is provided on a bottom surface of the recessed part 2a, the mounting metal layer 3 on which an electronic component 11 is mounted; a connection layer 4 which is connected with the mounting metal layer 3 and extends to an inner wall surface of the recessed part; and a via which is connected with the connection layer 4, the via where a width increases from the inner wall surface of the recessed part 2a toward the outer wall surface 2b facing the inner wall surface on a longitudinal section.

Description

  The present invention relates to, for example, a wiring board on which electronic components are mounted and an electronic device using the wiring board.

  For example, as a wiring board for mounting electronic components such as a sensor element such as an acceleration sensor element, a semiconductor element, an imaging element, a light emitting element, a capacitor element, a coil, a resistor, and a vibrator, a ceramic ceramic such as an aluminum oxide sintered body is used. A rectangular plate-like (cuboid) insulating base formed by laminating a plurality of insulating layers made of a bonded body, a wiring conductor provided from the main surface of the insulating base to the other main surface facing the other, and other insulating bases A wiring board provided with an external electrode provided on the main surface and electrically connected to the wiring conductor is widely used.

  About this wiring board, after mounting an electronic component on the bottom surface of the concave portion of the insulating base, the electrode of the electronic component is electrically connected to the wiring conductor of the insulating base via a bonding wire, etc. In this way, an electronic device that is mounted as a component on an external electric circuit constituting an electronic device such as a computer or a mobile phone is formed. In this electronic device, if the external electrode is connected to face an external electric circuit (an electric circuit formed on a mounting board such as a printed circuit board), the electrode of the electronic component and the external electric circuit are connected via the wiring conductor. Electrically connected.

  In recent years, in order to effectively use the functions of electronic components mounted on a wiring board, so-called vertical wiring is used in which electronic components are mounted on the bottom surface of a recess and the outer wall surface of an insulating substrate is bonded to a mounting board. There is a substrate.

JP-A-5-206324

  For example, if the electronic component is an acceleration sensor element, the vertical wiring board as described above is mounted in order to effectively detect acceleration in the horizontal direction (lateral direction). In such a case, a conductor portion such as a thermal via is provided so as to penetrate the insulating substrate from the bottom surface of the recess where the electronic component is mounted to the back surface of the insulating substrate, and heat generated from the electronic component is transferred to the conductor portion. To dissipate outside.

  However, in order to transfer the heat generated from the electronic component from the conductor part to the mounting board, etc., it is necessary to provide a metal layer, etc. from the exposed part of the conductor part to the mounting board side. The heat generated from the components is not easily transmitted to the mounting board or the like. That is, if the heat generated from the electronic component is not sufficiently transmitted to the outside or the like, the electronic component is difficult to operate normally, and the characteristics and reliability are reduced. Further, since the metal layer is provided on the back surface of the insulating base, there is a possibility of causing a short circuit or the like during handling.

A wiring board according to one aspect of the present invention includes an insulating base having a recess and an outer wall surface, and is mounted on the bottom surface of the recess and mounted with an electronic component, and connected to the mounting metal layer. A connection layer extending to the inner wall surface of the recess, and connected to the connection layer, and in a longitudinal section, the width increases from the inner wall surface of the recess to the outer wall surface facing the inner wall surface. Have vias.

  According to another aspect of the present invention, an electronic device includes the wiring board having the above-described configuration and an electronic component mounted on the wiring board.

  In the wiring substrate according to one aspect of the present invention, a mounting metal layer provided on the bottom surface of the recess and on which an electronic component is mounted, a connection layer connected to the mounting metal layer and extending to the inner wall surface of the recess, and a connection A mounting metal on which an electronic component is mounted by having a via that is connected to the layer and has a width that increases from the inner wall surface of the recess toward the outer wall surface facing the inner wall surface in the longitudinal section. The heat conduction from the layer to the mounting board becomes linear and the heat conduction path becomes short, so that heat generated from the electronic component is easily transferred to the mounting board and the like. In addition, in the longitudinal section, since the via has a width that increases from the inner wall surface of the recess to the outer wall surface facing the inner wall surface, the heat generated from the electronic component is diffused in the lateral direction while being recessed. Since heat is transmitted from the inside to the outside, heat generated from the electronic component is easily transmitted to a mounting substrate or the like over a wide range.

  According to another aspect of the present invention, the electronic device includes the wiring board having the above-described configuration, whereby the characteristics and reliability of the electronic component can be improved.

(A) is a plane perspective view which shows the electronic device in embodiment of this invention, (b) is a longitudinal cross-sectional view in the AA line of the electronic device shown by (a). It is a longitudinal cross-sectional view which shows the other example of the electronic device in embodiment of this invention.

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

An electronic device according to an embodiment of the present invention will be described with reference to FIGS.
The electronic device according to this embodiment includes a wiring board 1 and an electronic component 11 mounted on the wiring board 1. The wiring substrate 1 has an insulating base 2, a mounting metal layer 3, a connection layer 4, and a via 5. 1 and 2, the electronic device is provided in a virtual XYZ space. Hereinafter, for convenience, the “upward direction” refers to the positive direction of the virtual Z axis.

  The insulating base 2 has a recess 2a and an outer wall surface 2b.

  The insulating base 2 is a mounting metal on which electronic parts 11 such as a sensor element such as an acceleration sensor element, a semiconductor element, an imaging element, a light emitting element, a capacitor element, a coil, a resistor, and a vibrator are mounted on the bottom surface of the recess 2a. For example, a ceramic such as an aluminum oxide sintered body, a mullite sintered body, a silicon carbide sintered body, an aluminum nitride sintered body, a silicon nitride sintered body, or a glass ceramic sintered body. It is formed of a sintered body. The insulating base 2 may be formed by laminating a plurality of insulating layers (not shown) made of such a ceramic sintered body, or by using a mold that can be molded into a predetermined shape. You may shape | mold by pressurizing a green sheet.

If the insulating base 2 is formed by laminating a plurality of insulating layers made of an aluminum oxide sintered body, for example, it can be manufactured by the following method. First, a sintering aid such as silicon oxide, magnesium oxide and calcium oxide is added to the aluminum oxide powder, and an appropriate organic binder and solvent are added and mixed to form a slurry. A ceramic green sheet is obtained by molding into a sheet shape by the calendering method or calender roll method, etc., and appropriate punching is performed on the ceramic green sheet, and if necessary, multiple sheets are laminated and fired at a high temperature (about 1600 ° C) It is manufactured by doing. Alternatively, the ceramic green sheet may be molded by pressurization using a mold that can be molded into a predetermined shape, and fired at a high temperature as described above.

  The mounting metal layer 3 is provided on the bottom surface of the recess 2a, and the electronic component 11 is mounted thereon.

  The connection layer 4 is connected to the mounting metal layer 3 and extends to the inner wall surface of the recess 2a.

  In this insulating substrate 2, an external electrode is provided on the outer wall surface 2b, and includes a through-hole conductor such as a via-hole conductor or a through-hole conductor from the bottom surface of the recess 2a in which the electronic component 11 is mounted to the outer electrode of the outer wall surface 2b. A wiring conductor is deposited. The external electrode is electrically connected to an electrode pad of an external electric circuit formed on the mounting substrate via a brazing material such as solder.

  When the insulating base 2 is made of ceramic, the mounting metal layer 3, the connection layer 4, the external electrode, and the wiring conductor are tungsten (W), molybdenum (Mo), manganese (Mn), silver (Ag), copper (Cu ) And the like, and the mounting metal layer 3, the connection layer 4, the external electrodes and the conductor paste for the wiring conductor are printed in a predetermined shape on the ceramic green sheet for the insulating substrate 2 by a screen printing method or the like, By firing at the same time as the ceramic green sheet, the insulating base 2 is formed at a predetermined position. Of the internal conductors, the through conductors penetrating the ceramic green sheet may be filled with through holes formed in the ceramic green sheet by printing a conductor paste. Such a conductor paste can be appropriately obtained by adding an appropriate solvent and a binder to a metal powder such as tungsten (W), molybdenum (Mo), manganese (Mn), silver (Ag), copper (Cu), and kneading them. It is produced by adjusting to a proper viscosity. In order to increase the bonding strength with the insulating substrate 2, glass or ceramics may be included.

  The via 5 is connected to the connection layer 4 and is provided in the longitudinal section from the inner wall surface of the recess 2a toward the outer wall surface 2b facing the inner wall surface. With such a configuration, heat conduction from the mounting metal layer 3 on which the electronic component 11 is mounted to the mounting substrate becomes linear, and the heat conduction path is short, so that the heat is generated from the electronic component 11. Heat is easily transferred to the mounting substrate and the like. Further, in the longitudinal section, since the via 5 has a width increasing from the inner wall surface of the recess 2a toward the outer wall surface 2b facing the inner wall surface, heat generated from the electronic component 11 is laterally generated. Therefore, the heat generated from the electronic component 11 is easily transmitted over a wide range to the mounting substrate or the like. The via 5 has a diameter that increases from the inner wall surface of the recess 2a toward the outer wall surface 2b facing the inner wall surface, for example. The outer wall surface 2b is provided with a pad 5a connected to the via 5.

  As shown in FIG. 1, when a plurality of vias 5 (three in FIG. 1) are arranged from the inner wall surface of the recess 2a to the outer wall surface 2b facing the inner wall surface, the heat generated from the electronic component 11 is mounted. It becomes easier to be transmitted to the substrate and the like, which is preferable.

  The via 5 and the pad 5a are formed at predetermined positions on the insulating base 2 by the same method as the mounting metal layer 3, the connection layer 4, the external electrode, and the wiring conductor.

In the longitudinal section, the via 5 gradually increases in width from the inner wall surface of the recess 2a toward the outer wall surface 2b. With such a configuration, the heat generated from the electronic component 11 is transferred to the recess 2.
This is preferable because it conducts radially and linearly from the inner side to the outer side of a and easily propagates to a mounting substrate or the like over a wide area.

  The via 5 has a stepwise increase in width from the inner wall surface of the recess 2a toward the outer wall surface 2b in the longitudinal section. With such a configuration, heat generated from the electronic component 11 is easily transmitted in a wide range to the mounting substrate and the like, and the width gradually increases from the inner wall surface of the recess 2a toward the outer wall surface 2b. Even if stress is generated in the lateral direction due to the difference in thermal expansion between the via 5 and the insulating base 2, the insulating layer of the insulating base 2 is not inclined, so that the via 5 comes out of the insulating base 2. It is preferable that stress is difficult to work on.

  The pad 5a is connected to an electrode pad of an external electric circuit formed on the mounting substrate via a brazing material such as solder.

  The electronic component 11 is mounted on the mounting metal layer 3 provided on the bottom surface of the recess 2 a of the wiring board 1. The electronic component 11 is mounted by wire bonding or flip chip connection.

  In addition, it is preferable that the pad 5a is provided on the outer wall surface 2b as a whole in the longitudinal section because heat generated from the electronic component 11 can be more effectively transferred to the mounting substrate and the like.

  Next, the manufacturing method of the wiring board 1 of this embodiment is demonstrated.

The insulating base 2 is made of, for example, an aluminum oxide (Al ₂ O ₃ ) -based sintered body, and has a recess 2 a in which the electronic component 11 is mounted on the mounting metal layer 3 provided on the bottom surface. When the insulating base 2 is made of an aluminum oxide sintered body whose main component is aluminum oxide (Al ₂ O ₃ ), silica (SiO ₂ ), magnesia (MgO) is used as a sintering aid for Al ₂ O ₃ powder. ), Calcia (CaO), etc. are added, and an appropriate binder, solvent and plasticizer are added, and then the mixture is kneaded to form a slurry. Thereafter, a ceramic green sheet for obtaining a large number of pieces is obtained by a conventionally known molding method such as a doctor blade method.

  Using this ceramic green sheet, the wiring substrate 1 is manufactured by the following steps (1) to (5).

  (1) A punching process using a punching die at a portion to be the recess 2a and a sloped and stepped formation process of the via 5 for pressing an inclined body, an elastic body such as a mold having a staircase or rubber, or rubber.

  (2) The mounting metal layer 3 on the bottom surface of the recess 2a, the connection layer 4 on the inner wall surface of the recess 2a, the external electrode, the via 5, the pad 5a on the outer wall surface 2b of the insulating base 2, and the outside of the outer wall surface 2b from the bottom surface of the recess 2a. A process of applying and applying a conductor paste for forming wiring conductors including through-hole conductors such as via-hole conductors and through-hole conductors over the electrodes.

  (3) The process of producing a ceramic green sheet laminate by laminating ceramic green sheets to be the respective insulating layers, or pressurizing the ceramic green sheet using a mold that can be formed into a shape to form the recess 2a and the outer wall surface 2b. The process of creating a molded body.

  (4) A step of cutting and separating the ceramic green sheet laminated body or molded body into a laminated body or molded body to be an individual insulating substrate 2 and firing them to obtain a sintered body having external electrodes and pads 5a.

(5) A step of depositing a metal plating layer on the surface of the external electrode and pad 5a for protecting the external electrode and pad 5a to prevent oxidation and facilitating brazing.

  Since this wiring board 1 can be produced in a lump by collecting many of them, it can be manufactured at a lower cost than a semiconductor package of a type in which a metal frame is provided on a ceramic substrate, and has high versatility. . In this case, a dividing groove is formed along a portion serving as the outer edge of the multi-cavity wiring board 1 obtained by firing, a method of breaking along the dividing groove and dividing, a slicing method, or the like Thus, it is possible to use a method of cutting along a portion that becomes the outer edge of the wiring board 1. In addition, although a division | segmentation groove | channel can be formed by cutting smaller than the thickness of the wiring board 1 formed by multi-slicing with a slicing apparatus after baking, the ceramic green sheet laminated body for wiring boards 1 formed by multi-slicing Alternatively, it may be formed by pressing a cutter blade against the molded body or by cutting with a slicing device smaller than the thickness of the laminated body or molded body.

  In addition, by firing individual laminates or molded bodies cut out from ceramic green sheet laminates or molded bodies, or ceramic green sheet laminates or molded bodies having a large number of wiring boards 1, each external electrode, pad 5a is fired and deposited. That is, the external electrode and the pad 5a are formed with a thickness of 5 to 30 μm, and the wiring conductor of the input / output terminal to which the electronic component 11 is electrically connected is formed with a thickness of 5 to 25 μm.

Further, the mounting metal layer 3, the connection layer 4, the pad 5 a, the external electrodes, and the portions exposed on the surface of the insulating base 2 of the wiring conductor are protected and oxidized, and the electrode pads of the electronic component 11 and the mounting substrate are used. In order to increase the bonding strength with the metal layer 3, the mounting metal layer 3, the connection layer 4, the pad 5a, the surface of the external electrode, and the portion exposed on the surface of the insulating base 2 of the wiring conductor, Ni having a thickness of 0.5 to 10 μm
A plating layer is applied, or this Ni plating layer and gold (Au) having a thickness of 0.5 to 3 μm
It is preferable to deposit the plating layers sequentially.

  The electronic component 11 is mounted on the wiring board 1 formed in this way. The electronic device having the electronic component 11 mounted on the mounting metal layer 3 provided on the bottom surface of the recess 2a is mounted on the mounting metal layer 3 of the recess 2a by joining the mounting substrate with a soldering material such as solder. The electronic component 11 is electrically connected to the electrode pad of the mounting board via the wiring conductor and the external electrode. The electronic component 11 is, for example, a sensor element such as an acceleration sensor element, a semiconductor element, an imaging element, a light emitting element, a capacitive element, a coil, a resistor, a vibrator, and the like. The electronic component 11 is wire-bonded or flip-chip connected to the wiring conductor of the wiring board 1, and each electrode of the electronic component 11 is electrically connected by a gold bump, solder, or the like or a bonding wire. Furthermore, as a so-called underfill, for example, a resin as a bonding material such as an epoxy resin is provided between the outer wall surface 2b of the wiring board 1 and the mounting board and bonded. Note that, instead of using the gold bumps or solder described above, a connection member made of a conductive resin (anisotropic conductive resin or the like) may be used for electrical connection between each electrode of the electronic component 11 and the plurality of wiring conductors. Good.

  In addition, the electronic device may connect the external electrode and the electrode pad of the mounting substrate using a bonding member made of a conductive resin instead of using the brazing material such as solder described above. In addition, the bonding member such as an anisotropic conductive resin is placed on the mounting substrate and then subjected to pressure bonding so that the external electrode of the wiring substrate 1 and the electrode pad of the mounting substrate are electrically connected, and the anisotropic conductive resin. A bonding member such as the above may be provided between the outer wall surface 2b of the wiring board 1 and the mounting board. In this case, the manufacturing process can be simplified, a bonding member for connecting the external electrode of the wiring board 1 and the electrode pad of the mounting board, and a bonding member provided between the outer wall surface 2b of the wiring board 1 and the mounting board. Are made of the same material, and the bonding strength at the entire bonding portion between the wiring board 1 and the mounting board can be made uniform, so even if an external force is applied to the electronic device, the external force is not easily concentrated locally. , Because stress is easily dispersed.

  The wiring board 1 of the present embodiment includes an insulating base 2 having a recess 2a and an outer wall surface 2b. The mounting metal layer 3 is provided on the bottom surface of the recess 2a and on which an electronic component 11 is mounted, and the mounting metal layer. 3 and connected to the connection layer 4 extending to the inner wall surface of the recess, and in the longitudinal section, the width from the inner wall surface of the recess 2a toward the outer wall surface 2b facing the inner wall surface Is getting bigger. With such a configuration, the length of the mounting metal layer 3 and the connection layer 4 is short, and in the longitudinal section, the width increases from the inner wall surface of the recess 2a toward the outer wall surface 2b facing the inner wall surface. Since the via 5 is provided, the heat generated from the electronic component 11 is more easily transmitted to the mounting substrate or the like. In addition, since the mounting metal layer 3 and the connection layer 4 are provided in the recess 2a of the wiring board 1, it is possible to suppress the possibility of causing a short circuit or the like during handling.

  The electronic device according to the present embodiment includes the wiring board having the above-described configuration, so that the characteristics and reliability of the electronic component can be improved.

DESCRIPTION OF SYMBOLS 1 ... Wiring board 2 ... Insulation base | substrate 2a ...... Recessed part 2b ... Outer wall surface 3 ... Mounting metal layer 4 ... Connection layer 5 ... ... Via 5a ... Pad
11 ・ ・ ・ ・ ・ Electronic parts

Claims (4)

An insulating base having a recess and an outer wall surface,
A mounting metal layer provided on the bottom surface of the recess and on which an electronic component is mounted;
A connection layer connected to the mounting metal layer and extending to the inner wall surface of the recess;
A wiring board having a via which is connected to the connection layer and has a width increasing from an inner wall surface of the recess to the outer wall surface facing the inner wall surface in a longitudinal section. .   The wiring board according to claim 1, wherein a width of the via gradually increases from an inner wall surface of the concave portion toward the outer wall surface in a longitudinal section.   2. The wiring board according to claim 1, wherein the via has a stepwise increase in width from an inner wall surface of the recess to the outer wall surface in a longitudinal section. A wiring board according to claim 1;
An electronic device comprising: an electronic component mounted on the wiring board.

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