JP6166194B2 - Wiring board, electronic device and electronic module - Google Patents

Description

  The present invention relates to a wiring board, an electronic device, and an electronic module.

  2. Description of the Related Art Conventionally, a wiring conductor is provided inside or on the surface of an insulating substrate, and a cutout portion is provided from the side surface to the lower surface of the insulating substrate and an inner surface electrode connected to the wiring conductor is provided on the inner surface thereof. When an electronic device including a wiring board is bonded to, for example, an external circuit board using a bonding material such as solder, the inner surface electrode is bonded to the external circuit board via a bonding material such as solder.

JP 2002-158509 A

  In recent years, with the miniaturization of the wiring board, the wiring conductor and the inner surface electrode have been made finer and thinner, and the inner electrode may be formed thin at the connection portion with the wiring conductor. In such a wiring board, if a large current is applied from the external circuit board to the inner surface electrode, the current path from the outer circuit board to the wiring board is reduced during operation of the electronic device, and the connection portion between the inner surface electrode and the wiring conductor Since the cross-sectional area of the current path is the smallest in the vicinity, current concentration occurs, and there is a concern that the connection portion between the inner surface electrode and the wiring conductor may be disconnected or have high resistance. If the electronic component is a light emitting element, there is a concern that it may not emit light normally.

  According to one aspect of the present invention, the wiring board includes an insulating base having a notch opening in the main surface and the side surface, an inner surface electrode provided on the inner surface of the notch, A wiring conductor provided inside the insulating base and connected to the inner surface electrode at an end opposite to the main surface of the inner surface electrode, and the inner surface electrode is connected to the wiring conductor. The connecting portion has a large thickness.

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

  According to the wiring board according to one aspect of the present invention, an insulating base having a notch opening in the main surface and the side, an inner surface electrode provided on the inner side of the notch, and an insulating base A wiring conductor connected to the inner surface electrode at an end of the inner surface electrode opposite to the main surface of the insulating base, and the inner surface electrode has a thickness at the connection portion with the wiring conductor. Even if a large current is applied from the external circuit board to the wiring board, the cross-sectional area of the current path from the external circuit board to the wiring board becomes large in the vicinity of the connection portion between the inner surface electrode and the wiring conductor. Suppresses current concentration in the vicinity of the connection between the electrode and the wiring conductor, suppresses disconnection or high resistance at the connection between the inner electrode and the wiring conductor, and improves the reliability of electrical connection between the inner electrode and the wiring conductor. Good and Rukoto can. When the electronic component is a light-emitting element, a wiring board that can emit light satisfactorily can be obtained.

An electronic device according to another aspect of the present invention is improved in terms of electrical reliability and electrical characteristics by including the wiring board having the above configuration. When the electronic component is a light-emitting element, a light-emitting device that can emit light well over a long period of time can be obtained.

(A) is a top view which shows the electronic device in the 1st Embodiment of this invention, (b) is a bottom view of (a). (A) is sectional drawing in the AA of the electronic device shown by Fig.1 (a). (A) is a principal part expanded bottom view in the A section of the electronic device shown by FIG.1 (b), (b) is sectional drawing in the AA of (a). It is a principal part expanded sectional view in the other example of the electronic device in the 1st Embodiment of this invention. (A)-(d) is sectional drawing which shows the 1st manufacturing method of the inner surface electrode, wiring conductor, and extension electrode of the wiring board in the 1st Embodiment of this invention. (A) is sectional drawing which shows the electronic module which mounted the electronic device in FIG. 1 on the board | substrate for modules, (b) is a principal part expanded sectional view in the A section of (a). (A) is a top view which shows the electronic device in the 2nd Embodiment of this invention, (b) is a bottom view of (a). (A) is sectional drawing in the AA of the electronic device shown by Fig.7 (a). FIG. 7A is an enlarged bottom view of a main part of the electronic device A shown in FIG. 7B, and FIG. 7B is a cross-sectional view taken along line AA of FIG. It is a principal part expanded sectional view which shows the other example of the electronic device in the 2nd Embodiment of this invention. (A)-(d) is sectional drawing which shows the 2nd manufacturing method of the inner surface electrode, wiring conductor, and extension electrode of the wiring board in the 2nd Embodiment of this invention. (A)-(d) is sectional drawing which shows the 3rd manufacturing method of the inner surface electrode, wiring conductor, and extension electrode of the wiring board in the 2nd Embodiment of this invention. (A) is a top view which shows the other example of the electronic device in the 2nd Embodiment of this invention, (b) is a bottom view of (a). (A) is a top view which shows the other example of the electronic device in the 3rd Embodiment of this invention, (b) is sectional drawing in the AA of (a).

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

(First embodiment)
As shown in FIGS. 1, 2, and 6, the electronic device according to the first embodiment of the present invention includes a wiring board 1 and an electronic component 2 provided on the upper surface of the wiring board 1. Yes. As in the example shown in FIG. 6, the electronic device is connected to the external circuit substrate 5 (for example, the module substrate 5) that constitutes the electronic module, for example, using the bonding material 6.

  The wiring board 1 includes an insulating base 11 having a notch 12 that opens to the main surface and side surfaces, an inner surface electrode 13 provided on the inner side 12a of the notch 12, and an insulating base 11 inside. And a wiring conductor 14 connected to the inner surface electrode 13 at an end opposite to the main surface of the inner surface electrode 13. The inner surface electrode 13 is thicker at the connection portion with the wiring conductor 14. The inner surface electrode 13 is thicker at the corners of the notch 12 in the thickness direction of the insulating base 11. 1, 2, and 6, the electronic device is mounted on an xy plane in a virtual xyz space. 1, 2, and 6, the upward direction refers to the positive direction of the virtual z axis.

  The insulating base 11 is composed of a plurality of insulating layers 11a, has an upper surface including a mounting area for the electronic component 2, and has a rectangular plate shape in plan view. The insulating base 11 functions as a support for supporting the electronic component 2, and the electronic component 2 is bonded and fixed to the mounting area in the center of the upper surface via a bonding member such as a low melting point brazing material or a conductive resin. The

  As the insulating substrate 11, for example, ceramics such as an aluminum oxide sintered body (alumina ceramic), an aluminum nitride sintered body, a mullite sintered body, or a glass ceramic sintered body can be used.

  If the insulating substrate 11 is made of, for example, an aluminum oxide sintered body, a suitable organic binder and solvent are added to and mixed with raw material powders such as aluminum oxide, silicon oxide, magnesium oxide and calcium oxide to form a slurry. Then, this is formed into a sheet shape by the doctor blade method or the calender roll method to obtain a ceramic green sheet. After that, the ceramic green sheet is subjected to appropriate punching processing, and a plurality of these are laminated to obtain a high temperature (about 1600 Manufactured by baking at a temperature of ° C.

  The notch 12 is opened on the main surface and side surface of the insulating base 11. In the example shown in FIGS. 1 to 4, the insulating base 11 is formed so as to open on the lower surface and side surfaces. In the example shown in FIGS. 1 to 4, the notch 12 is formed in a rectangular shape with a corner having an arc shape in plan view, and is formed long along the outer side of the insulating base 11. Note that the cutout portion 12 may have a semicircular shape, a semi-elliptical shape, a semi-oval shape, or a shape in which a plurality of cutout portions 12 overlap each other in plan view. Such cutouts 12 are formed by forming through holes to be the cutouts 12 in some of the ceramic green sheets for the insulating substrate 11 by laser machining or punching with a mold. The

The inner surface electrode 13 is provided on the inner surface 12 a of the notch 12. The inner side surface 12 a is a surface extending from the main surface (lower surface) of the insulating base 11 in the thickness direction of the insulating base 11 among the inner surface of the cutout portion 12. The wiring conductor 14 is provided on the surface and inside of the insulating base 11. In the example shown in FIGS. 1 to 4, a main surface electrode 13 a connected to the inner surface electrode 13 is provided on the main surface where the notch 12 is open. In addition, it is an external electrode by the structure containing the inner surface electrode 13 and the main surface electrode 13a. The inner surface electrode 13 and the wiring conductor 14 are the end of the inner surface electrode 13 opposite to the main surface of the insulating base 11, in other words, the rear side of the notch 12, that is, the main surface of the insulating base 11 in the notch 12. It is connected at the part farthest from the opening. The inner surface electrode 13 may be extended to the inside of the insulating base 11 by about 0.05 to 0.1 mm so as to surround the notch portion 12 in a plan view at the connection portion with the wiring conductor 14. The external electrodes including the inner surface electrode 13 and the main surface electrode 13 a are for bonding to the external circuit board 5. The inner surface electrode 13, the main surface electrode 13a, and the wiring conductor 14 are for electrically connecting the electronic component 2 mounted on the wiring board 1 and the external circuit board 5. The wiring conductor 14 electrically connects the wiring conductors (surface wiring and internal wiring) provided on the surface or inside of the insulating base 11 and the wiring conductors positioned vertically through the insulating layer 11a constituting the insulating base 11. And a through conductor connected to the.

The inner surface electrode 13 is thicker at the connection portion with the wiring conductor 14. Here, the thick thickness means that the thickness t1 at the connection portion with the wiring conductor 14 is larger than the thickness t2 on the opening side of the cutout portion 12a (t1> t2) as in the example shown in FIG. Is shown. Thus, even if a large current is applied from the external circuit board 5 to the wiring board 1 by increasing the thickness of the inner surface electrode 13 at the connection portion with the wiring conductor 14, the external circuit board 5 to the wiring board 1. Since the cross-sectional area of the current path increases in the vicinity of the connection portion between the inner surface electrode 13 and the wiring conductor 14, current concentration in the vicinity of the connection portion between the inner surface electrode 13 and the wiring conductor 14 is suppressed, and the inner surface electrode 13 and the wiring conductor 14 It is possible to suppress disconnection or high resistance of the connection portion between the inner surface electrode 13 and the wiring conductor 14 and to improve the electrical connection reliability. When the electronic component 2 is a light emitting element,
It can be set as the wiring board which can light-emit favorably.

Here, the thickness t1 at the connection portion between the inner surface electrode 13 and the wiring conductor 14 is 1.1 × t2 ≦
When t1 ≦ 3 × t2, current concentration in the vicinity of the connection portion between the inner surface electrode 13 and the wiring conductor 14 is satisfactorily suppressed, and the connection portion between the inner surface electrode 13 and the wiring conductor 14 may be disconnected or have high resistance. The electrical connection reliability between the inner surface electrode 13 and the wiring conductor 14 can be improved.

  Further, in the thickness direction of the wiring board 1, the length l1 of the thick portion 12b of the inner surface electrode 13 is set larger on the main surface side of the insulating base 11 than the thickness t3 of the wiring conductor 13 connected to the inner surface electrode 13. (L1> t3), and the current concentration flowing from the inner surface electrode 13 on the main surface side of the insulating base 11 to the wiring conductor 14 in the vicinity of the connection portion between the inner surface electrode 13 and the wiring conductor 14 is further suppressed. It is possible to suppress disconnection or high resistance at the connection portion with the wiring conductor 14 and to improve the electrical connection reliability between the inner surface electrode 13 and the wiring conductor 14.

  For the inner surface electrode 13, the main surface electrode 13a, and the wiring conductor 14, a metal material such as tungsten (W), molybdenum (Mo), manganese (Mn), silver (Ag), or copper (Cu) can be used. For example, when the insulating substrate 11 is made of an aluminum oxide sintered body, a conductive paste obtained by adding and mixing a suitable organic binder and solvent to a refractory metal powder such as W, Mo or Mn is insulated. The ceramic green sheet to be the base 11 is preliminarily printed and applied in a predetermined pattern by a screen printing method, and is fired simultaneously with the ceramic green sheet to be the insulating base 11, thereby being deposited on a predetermined position of the insulating base 11. When the wiring conductor 14 is a through conductor, a through hole is formed in the green sheet by punching by a die or punching or laser processing, and a conductive paste for the wiring conductor 14 is filled into the through hole by a printing method. It is formed by placing. The inner surface electrode 13 is formed by printing and applying a conductive paste for the inner surface electrode 13 in a region which is an inner surface of the through hole that becomes the notch 12. The main surface electrode 13a is formed by printing and applying a conductor paste to be the main surface electrode 13a to the ceramic green sheet to be the insulating base 11.

  The wiring board 1 in the first embodiment of the present invention can be manufactured, for example, by the following manufacturing method.

In the first manufacturing method, as in the example shown in FIG. 5A, the through hole 112 for the wiring conductor 14 is formed in the ceramic green sheet 111 to be the insulating base 11. Further, after the conductor paste 114 for the wiring conductor 14 is printed and applied to the surface of the ceramic green sheet 211, the through hole 112 for the wiring conductor 14 and the through hole 212 for the cutout portion 12 are formed. Here, by forming a part of the conductor paste 114 for the wiring conductor 14 so as to overlap with a region where the through hole 212 for the notch 12 is provided, the through hole 212 for the notch 12 is formed. At this time, the conductor paste 114 for the wiring conductor 14 is formed along the opening edge of the notch 12. Then, as in the example shown in FIG. 5B, the conductor paste 113 for the inner surface electrode 13 is applied and printed on the inner surface of the through-hole 212 that becomes the notch 12 of the ceramic green sheet 211 by screen printing. . Here, the conductor paste 113 for the inner surface electrode 13 and the conductor paste 114 for the wiring conductor 14 are connected at the end of the conductor paste for the inner surface electrode 13 opposite to the main surface of the insulating substrate 11. In addition, here, the thickness of the conductor paste 113 for the inner surface electrode 13 on the side (the upper side in FIG. 4) of the through hole 212 for the notch 12 that becomes the connection portion between the inner surface electrode 13 and the wiring conductor 14 Printing is applied so as to be thicker than the other opening side of the through hole 212 for the notch 12. Here, the conductor paste 113 for the inner surface electrode 13 passes through the inner surface of the through-hole 212 for the notch portion 12 by printing and applying the conductor paste 113 for the inner surface electrode 13 multiple times. Of the hole 212, the thickness of the side serving as the connection portion between the inner surface electrode 13 and the wiring conductor 14 may be larger than the other opening side of the through hole 212 for the notch 12. Further, the conductor paste 113a for the main surface electrode 13a is applied and printed on the surface of the ceramic green sheet 211 by a screen printing method. Further, the conductor paste 114 for the wiring conductor 14 is applied and printed on the surface of the ceramic green sheet 111 and the through hole 112 for the wiring conductor 14 by a screen printing method. Then, by laminating and pressing the ceramic green sheet 111 and the ceramic green sheet 211, the conductor for the inner surface electrode 13 is connected at the connecting portion between the conductor paste 113 for the inner surface electrode 13 and the conductor paste 114 for the wiring conductor 14. By forming a ceramic raw laminate that becomes the insulating base 11 having a thick paste 113 and firing the ceramic raw laminate, as shown in FIG. 5C, at the corner of the notch 12a, An insulating substrate 11 having a recess 312 with a thick inner electrode 13 is formed. Further, as in the example shown in FIG. 5D, the recess 312 is divided to provide the inner surface 12 a of the notch 12, and at the connecting portion between the inner surface electrode 13 and the wiring conductor 14, the thickness is reduced. The wiring board 1 having the inner electrode 13 having a thicker thickness can be manufactured.

A plating layer is deposited on the exposed surfaces of the inner surface electrode 13, the main surface electrode 13a, and the wiring conductor 14 by an electrolytic plating method or an electroless plating method. The plating layer is made of a metal having excellent corrosion resistance such as nickel, copper, gold, or silver, and connectivity with a connection member.
A nickel plating layer of about 5 μm and a gold plating layer of about 0.1 to 3 μm, or a nickel plating layer of about 1 to 10 μm and a silver plating layer of about 0.1 to 1 μm are sequentially deposited. As a result, corrosion of the inner surface electrode 13, the main surface electrode 13a, and the wiring conductor 14 can be effectively suppressed, and the connection between the wiring conductor 14 and the electronic component 2 and the connection member 3 such as the wiring conductor 14 and bonding wire can be reduced. And the connection between the inner surface electrode 13 and the main surface electrode 13a and the connection pad 51 for connection formed on the external circuit substrate 5 (module substrate 5) can be strengthened. Also, on the wiring conductor 14 on which the electronic component 2 is to be mounted, a copper plating layer having a thickness of about 10 to 80 μm is interposed and deposited, so that the heat of the electronic component 2 can be easily radiated. Alternatively, the main surface electrode 13a may be deposited with a copper plating layer having a thickness of about 10 to 80 μm to facilitate heat dissipation from the wiring board 1 to the external circuit board 5. Good.

  An electronic device can be manufactured by mounting the electronic component 2 on the upper surface of the wiring board 1. The electronic component 2 mounted on the wiring board 1 is a semiconductor element such as an IC chip or an LSI chip, a light emitting element, a piezoelectric element such as a crystal vibrator or a piezoelectric vibrator, and various sensors. For example, when the electronic component 2 is a wire bonding type semiconductor element, the semiconductor element is fixed on the wiring conductor 14 by a bonding member such as a low melting point brazing material or a conductive resin, and then connected to a bonding wire or the like. The electrode of the semiconductor element and the wiring conductor 14 are electrically connected via the member 3 to be mounted on the wiring board 1. For example, when the electronic component 2 is a flip-chip type semiconductor element, the semiconductor element is connected via a connecting member 3 such as a solder bump, a gold bump, or a conductive resin (anisotropic conductive resin, etc.) The electrode of the semiconductor element and the wiring conductor 13 are mounted on the wiring board 1 by being electrically and mechanically connected. In addition, a plurality of electronic components 2 may be mounted on the wiring board 1, or small electronic components such as a resistance element and a capacitive element may be mounted as necessary. Further, the electronic component 2 is sealed with a sealing material 4 made of resin, glass, or the like, a lid made of resin, glass, ceramics, metal, or the like, as necessary.

  As in the example shown in FIG. 6, the electronic device of the present embodiment is connected to the connection pad 51 of the module substrate 5 via the bonding material 6 such as solder to form an electronic module. The bonding material 6 is bonded to the inner surface electrode 13 and the main surface electrode 13a in the notch 12 and is inclined so as to spread from the inner end of the notch 12 to the connection pad 51. By adopting such a configuration, even if stress is generated in the electronic device due to an external force or the like during handling, the stress is dispersed by the bonding material 6 inclined so as to spread, and the electronic device becomes a module substrate. Thus, an electronic module with improved connection reliability can be obtained.

According to the wiring substrate 1 of the present embodiment, the insulating base 11 having the cutout portion 12 opened on the main surface and the side surface, the inner surface electrode 13 provided on the inner surface of the cutout portion 12, and the insulation The inner surface electrode 13 has a wiring conductor 14 connected to the inner surface electrode 13 at the end of the inner surface electrode 13 opposite to the main surface of the insulating substrate 11, and the inner surface electrode 13 Since the connection portion with the conductor 11 is thick, even if a large current is applied from the external circuit board 5 to the wiring board 1, the cross-sectional area of the current path from the external circuit board 5 to the wiring board 1 is the inner surface electrode 13. Is increased in the vicinity of the connection portion between the inner surface electrode 13 and the wiring conductor 14, and current concentration in the vicinity of the connection portion between the inner surface electrode 13 and the wiring conductor 14 is suppressed, and the connection portion between the inner surface electrode 13 and the wiring conductor 14 is disconnected or has a high resistance. The electrical connection between the inner surface electrode 13 and the wiring conductor 14 is suppressed. It can be made good connection reliability. In the case where the electronic component 2 is a light emitting element, the wiring board 1 can emit light satisfactorily.

  Further, as in the example shown in FIGS. 1 and 3, the portion 13 b where the thickness of the inner surface electrode 13 is thick in plan view is provided along the inner surface 12 a of the notch portion 12. Even when a large current is applied from the external circuit board 5 to the wiring board 1, the portion 13 b where the thickness of the inner surface electrode 13 is thick is provided along the inner side surface 12 a of the notch 12. The applied current flows over a wide range to the portion 13b where the thickness of the inner surface electrode 13 is increased, and the cross-sectional area of the current path is effectively suppressed from decreasing rapidly. It is possible to effectively suppress the current concentration at the connection portion with 14 and to improve the electrical connection reliability between the inner surface electrode 13 and the wiring electrode 14.

  Further, as in the example shown in FIG. 4, the shape of the inner surface electrode 13 is such that the thickness at the connection portion with the wiring conductor 14 gradually increases toward the end opposite to the main surface of the insulating base 11. When the surface of the inner surface electrode 13 is a concave curved surface, the inner surface electrode 13 is thicker at the connection portion with the wiring conductor 14, even if an external force is applied to the inner surface electrode 13, The stress due to the external force is dispersed by the concave curved surface of the inner surface electrode 13, so that the inner surface electrode 13 can be prevented from being chipped.

Further, the inner surface electrode 13 may have a lower sheet resistivity on the surface side of the inner surface electrode 13 than the cutout portion 12 side of the inner surface electrode 13. With such a configuration, current concentration inside the connection portion between the inner surface electrode 13 and the wiring conductor 14 is suppressed, and disconnection or high resistance inside the connection portion between the inner surface electrode 13 and the wiring conductor 14 is suppressed. As a result, the electrical connection reliability between the inner surface electrode 13 and the wiring conductor 14 can be improved. In the case where the electronic component 2 is a light emitting element, the wiring board 1 can emit light satisfactorily. Such an inner surface electrode 13 is formed, for example, by printing and applying the conductor paste 113 for the inner surface electrode 13 having different sheet resistivity after firing several times.

  The wiring board 1 in the present embodiment can be suitably used in a small and high-power electronic device, and electrical connection in the wiring board 1 can be favorably achieved. For example, the electronic component 2 can be suitably used as a small wiring board for mounting a light emitting element on which a high light emitting element is mounted.

  According to the electronic device of the present embodiment, since the wiring board 1 having the above-described configuration and the electronic component 2 mounted on the wiring board 1 are provided, the electrical reliability and the electrical characteristics are improved. . When the electronic component 2 is a light emitting element, a light emitting device that can emit light satisfactorily over a long period of time can be obtained.

(Second Embodiment)
Next, an electronic device according to a second embodiment of the present invention will be described with reference to FIGS.

  The electronic device according to the second embodiment of the present invention differs from the electronic device according to the first embodiment described above in that, as in the example shown in FIGS. This is that the surface of the inner surface electrode 13 in the connecting portion is a convex curved surface.

  According to the wiring board 1 in the second embodiment, the inner surface electrode 13 has a convex curved surface at the connection portion between the inner surface electrode 13 and the wiring conductor 14. Since there are no protruding corners, cracks in the bonding material 6 starting from the corners of the inner surface electrode 13 are suppressed, and the connection reliability between the electronic device and the external circuit board 5 is improved. Can do. When the electronic component 2 is a light emitting element, it can be a wiring board that can emit light satisfactorily.

  Further, in the second embodiment, when the thick portion 13b of the inner surface electrode 13 is a convex curved surface along the entire circumference of the inner surface 12a of the notch portion 12 in plan view, the inner surface electrode 13 is better. Current concentration in the vicinity of the connection between the wiring conductor 14 and the wiring conductor 14 can be suppressed.

  In the second embodiment, the notch 12 is provided inside the notch having a width larger than that of the notch 12 in plan view, as in the example shown in FIG. The electrode 13 is provided on the inner side surface 12 a of the notch 12. Thus, when the notch 12 is provided inside the notch having a width larger than that of the notch 12 in plan view, the inner surface electrode 13 is formed when the notch 12 is formed. Therefore, it is possible to suppress the peeling of the inner surface electrode 13 from the insulating base 11 or the occurrence of a short circuit between the inner surface electrodes 13 arranged adjacent to each other. 1 can be mounted on the external circuit board 5 satisfactorily. The insulating base 11 has an upper surface including a cavity 15 as in the example shown in FIGS. Such cavities 15 are formed by forming through holes to be cavities 15 in a plurality of ceramic green sheets by laser processing or punching with a mold on the ceramic green sheets, and forming these through holes. It can be formed by laminating the ceramic green sheets. In addition, when the insulating substrate 11 is thin, it is preferable that the through hole for the cavity 15 be formed with high accuracy by laminating ceramic green sheets and then forming by laser processing or punching with a mold. Further, as in the example shown in FIGS. 7 to 11, the notch 12 is about 25% to 75% of the width of the side wall of the cavity.

  When the cavity 15 is a space for mounting a light emitting element, the angle θ formed by the inner surface of the cavity 15 and the bottom surface of the cavity 15 is an obtuse angle, and may be 110 ° to 145 °. When the angle θ is in such a range, it is easy to stably and efficiently form the inner surface of the through-hole serving as the cavity 15 by punching, and the light emitting device using the wiring board 1 can be easily downsized. In addition, the light emitted from the light emitting element can be emitted well toward the outside. The cavity 15 having such an inner surface of the angle θ is formed by punching a ceramic green sheet using a punching die in which the clearance between the punch diameter and the die hole diameter is set large. In other words, by setting the clearance of the die hole diameter larger than the punch diameter of the punching die, the green sheet is punched when the ceramic green sheet is punched from the main surface side to the other main surface side. Is formed so that the diameter of the through hole spreads from the main surface side to the other main surface side by shearing from the edge of the contact surface to the edge of the contact surface with the die hole. At this time, the angle of the inner surface of the through hole formed in the ceramic green sheet can be adjusted by setting the clearance between the diameter of the punch and the diameter of the die hole according to the thickness of the ceramic green sheet. Such a punching method is high in productivity because the angle θ formed by the inner surface of the cavity 15 and the bottom surface of the cavity 15 can be set to a desired angle only by punching.

In addition, after forming a through hole having an angle θ of about 90 degrees by processing with a punching die having a small clearance between the diameter of the punch and the diameter of the die, a truncated cone shape or a truncated pyramid shape is formed on the inner surface of the through hole. A through-hole having an angle θ extending from one main surface side to the other main surface side as described above may be formed by pressing the mold. In such a case, the angle θ formed by the inner surface of the cavity 15 and the bottom surface of the cavity 15 can be adjusted with higher accuracy.

  When the wiring substrate 1 has an insulating base 11 having an upper surface including the cavity 15 on which the light emitting element is mounted, for example, a reflection layer for reflecting light emitted from the light emitting element is provided on the inner wall surface of the cavity 15. It may be done. The reflective layer has, for example, a metal conductor layer provided on the inner wall surface of the cavity 15 and a plating layer deposited on the metal conductor layer. The metal conductor layer can be formed by the same material and method as the inner surface electrode 13, the main surface electrode 13 a, and the wiring conductor 14.

  For example, when a light emitting element is mounted on the wiring board 1, a silver plating layer is deposited on the outermost surface of the metal conductor layer, and gold plating is applied to the innermost electrode 13, the main surface electrode 13a, and the outermost surface of the wiring conductor 14. It is preferred to deposit the layer. The gold plating layer is superior in bondability to the electronic component 2, the connection member 3, and the bonding material 6 as compared with the silver plating layer, and the silver plating layer has a light reflectivity as compared with the gold plating layer. This is because it is expensive. Further, the outermost surface of the wiring conductor 14 and the metal conductor layer in the portion where the light emitting element is mounted may be an alloy plating layer of silver and gold, for example, an alloy plating layer that is a solid solution of silver and gold.

  The wiring board 1 in the second embodiment of the present invention can be manufactured, for example, by the following manufacturing method.

In the second manufacturing method, as in the example shown in FIG. 11A, the ceramic green sheets 111 and 211 to be the insulating base 11 are formed on the through hole 212 for the notch 12 and the through hole 115 for the cavity. And form. Further, the conductor paste 114 for the wiring conductor 14 is printed on the surface of the ceramic green sheet 211. At this time, printing is applied so that the end portion of the conductor paste 114 for the wiring conductor 14 is applied to the upper end portion of the inner surface of the through hole 212 that becomes the cutout portion 12. Then, as in the example shown in FIG. 11B, the conductor paste 113 for the inner surface electrode 13 is applied and printed on the inner surface of the through-hole 212 that becomes the cutout portion 12 of the ceramic green sheet 211 by screen printing. . Also,
A conductive paste 113a for the main surface electrode 13a is printed on the surface of the ceramic green sheet 211 by screen printing. Here, the conductor paste 113 for the inner surface electrode 13 is printed so as to cover the end portion of the wiring conductor 114 applied to the upper end portion of the inner surface of the through hole 212, and the conductor paste 113 for the inner surface electrode 13 and the wiring The conductor paste 114 for the conductor 14 is formed in connection with the convex curved surface. Then, the ceramic green sheet 111 and the ceramic green sheet 211 are laminated and pressed to form a ceramic green laminate that becomes the insulating base 11, and the ceramic green laminate is fired to obtain FIG. 11 (c). As shown in FIG. 5, the insulating base 11 having the recess 312 having the inner surface electrode 13 on the inner surface that becomes the notch 12 is formed. Here, when the ceramic green sheet 111 and the ceramic green sheet 211 are laminated and pressed, by pressing the overlapping portion of the conductor paste 113 for the inner surface electrode 13 and the conductor paste 14 for the wiring conductor 14, the inner surface The main surface of the inner surface electrode 13 at the connection portion between the electrode 13 and the wiring conductor 14 can be more preferably a convex curved surface. The end portion of the wiring conductor 14 extending to the inner side surface of the recess 312 is formed as the inner surface electrode 13, and the thickness of the inner surface electrode 13 is increased at the connecting portion between the inner surface electrode 13 and the wiring conductor 14. Further, as in the example shown in FIG. 11D, the recess 312 is divided so that it is provided on the inner surface 12a of the cutout portion 12, and at the connection portion between the inner surface electrode 13 and the wiring conductor 14, the projection A wiring board 1 having an inner surface electrode 13 having a large thickness on a curved surface can be manufactured.

Next, the third manufacturing method will be described. Similar to the second manufacturing method, the third manufacturing method is similar to the example shown in FIG. 12A, and the ceramic green sheet 111 that becomes the insulating base 11 is used.
211, the through hole 212 for the notch 12 and the through hole 115 for the cavity are formed. Also,
The conductor paste 113 for the inner surface electrode 13 is applied and printed on the inner surface of the through hole 212 that becomes the cutout portion 12 of the ceramic green sheet 211 by a screen printing method. Then, as in the example shown in FIG. 12B, the conductor paste 114 for the wiring conductor 14 is printed on the surface of the ceramic green sheet 211. At this time, the end portion of the conductor paste 114 for the wiring conductor 14 is printed and applied so as to cover the upper end portion of the inner surface electrode 13, and the conductor paste 113 for the inner surface electrode 13 and the conductor paste 114 for the wiring conductor 14 are connected. And a convex curved surface. Then, the ceramic green sheet 111 and the ceramic green sheet 211 are laminated and pressed to form a ceramic green laminate that becomes the insulating base 11, and the ceramic green laminate is fired to obtain FIG. 12 (c). As shown in FIG. 5, the insulating base 11 having the recess 312 having the inner surface electrode 13 on the inner surface that becomes the notch 12 is formed. Here, when the ceramic green sheet 111 and the ceramic green sheet 211 are laminated and pressed, by pressing the overlapping portion of the conductor paste 113 for the inner surface electrode 13 and the conductor paste 14 for the wiring conductor 14, the inner surface The main surface of the inner surface electrode 13 at the connection portion between the electrode 13 and the wiring conductor 14 can be more preferably a convex curved surface. The end portion of the wiring conductor 14 extending to the inner side surface of the recess 312 is formed as the inner surface electrode 13, and the thickness of the inner surface electrode 13 is increased at the connecting portion between the inner surface electrode 13 and the wiring conductor 14. Further, FIG. 11 (d)
As shown in the example shown in FIG. 4, the concave portion 312 is divided to provide the inner surface 12a of the cutout portion 12, and the convex curved surface is thick at the connection portion between the inner surface electrode 13 and the wiring conductor 14. The wiring board 1 having the inner surface electrode 13 can be manufactured.

Further, in the above manufacturing method, when the cutout portion 12 having a plurality of cutouts overlapped with each other, the conductor paste 113 for the inner surface electrode 13 is printed and applied to the through-hole that becomes a small cutout, and then the small cutout portion 12 is small. You may form the through-hole used as a notch and a large notch which partly cuts the conductor paste 113 for the inner surface electrodes 13 and the through-hole used as a notch.

  In addition, if the sheet resistance value of the wiring on the outside (side to be printed later) of the inner surface electrode 13 and the wiring conductor 14 on the outer side when they overlap each other in the connection portion is reduced, Current concentration inside the connection portion with the wiring conductor 14 is suppressed, and the connection portion between the inner surface electrode 13 and the wiring conductor 14 is prevented from being disconnected or having high resistance, and the electrical connection between the inner surface electrode 13 and the wiring conductor 14 is suppressed. Connection reliability can be improved.

Further, the wiring conductor 14 is thick at the connection portion with the inner surface electrode 13 as in the examples shown in FIGS. Here, being thicker at the connection portion with the inner surface electrode 13 means that, for example, the thickness of the wiring conductor 14 at the connection portion with the inner surface electrode 13 is larger than the wiring conductor 14 at the portion led to the bottom surface of the cavity 15. It shows that it is thick. As described above, when the thickness of the wiring conductor 14 at the connection portion with the inner surface electrode 13 is increased, even if a large current is applied from the external circuit board 5 to the wiring board 1, the current from the external circuit board 5 to the wiring board 1. Since the cross-sectional area of the path becomes large in the vicinity of the connection portion between the inner surface electrode 13 and the wiring conductor 14 in the wiring conductor 14, current concentration in the vicinity of the connection portion between the inner surface electrode 13 and the wiring conductor 14 is further suppressed. It is possible to better suppress the disconnection or high resistance at the connection portion between the inner electrode 13 and the wiring conductor 14, and to improve the electrical connection reliability between the inner surface electrode 13 and the wiring electrode 14. In addition, by reducing the thickness of the mounting part of the electronic component 2 and making it easier to suppress deformation such as warpage in the electronic component 2 mounting region due to the firing shrinkage difference between the insulating substrate 11 and the wiring conductor 14 during firing. The component 2 can be satisfactorily mounted on the wiring conductor 14 or the connecting member 3 can be satisfactorily connected to the wiring conductor 14. For example, when the conductor paste 113 for the inner surface electrode 13 is printed and applied, the wiring conductor 14 is formed from the inner surface of the through-hole 212 for the notch portion 12 through the ceramic green sheet 211 when the conductor paste 113 for the inner surface electrode 13 is printed. The conductor paste 113 for the inner surface electrode 13 and the conductor for the wiring conductor 14 are applied on the surface of the ceramic green sheet 211 at the opening edge of the through hole 212 for the notch 12. The paste 114 may be formed so as to overlap with the paste 114, and the conductor paste 113 for the inner surface electrode 13 led to the surface of the ceramic green sheet 211 becomes the wiring conductor 14 after firing. Further, as shown in FIGS. 8 to 10, if the wiring conductor 14 disposed at the upper end of the inner surface electrode 13 is embedded in the insulating base 11, a large current flows from the external circuit board 5 to the wiring board 1. Even if applied, the current flowing in the thickened portion 13b of the inner surface electrode 13 is likely to flow to the buried side, effectively suppressing the cross-sectional area of the current path from rapidly decreasing, The current concentration in the vicinity of the connection portion between the electrode 13 and the wiring conductor 14 is suppressed, and the connection portion between the inner surface electrode 13 and the wiring conductor 14 is suppressed from being broken or high resistance. Electrical connection reliability can be improved.

  Further, as in the example shown in FIG. 10, when the thickest portion of the thickened portion 13 b of the inner surface electrode 13 is located on the upper surface of the notch portion 12, when connecting to the external circuit board 5, solder or the like Since the joining material 6 is easily joined well even at the upper end portion of the inner surface electrode 13, and the current flowing through the thickened portion 13b of the inner surface electrode 13 is more likely to flow to the buried side, the inner surface electrode The electrical connection reliability between 13 and the wiring conductor 14 can be further improved.

  Similar to the first embodiment, the wiring board 1 of the second embodiment can be suitably used in a small and high-power electronic device, and electrical connection in the wiring board 1 can be favorably achieved. . For example, the electronic component 2 can be suitably used as a small wiring board for mounting a light emitting element on which a high light emitting element is mounted.

(Third embodiment)
Next, an electronic device according to a third embodiment of the present invention will be described with reference to FIG.

  The electronic device according to the third embodiment of the present invention is different from the electronic device according to the first embodiment described above in that the notch 12 is a mounting surface of the electronic component 2 as in the example shown in FIG. And the same main surface (hereinafter also referred to as the upper surface) and side surfaces.

  According to the wiring board of the third embodiment of the present invention, the inner surface electrode 13 is thicker at the connection portion with the wiring conductor 14 as in the case of the wiring board of the first embodiment. Even when a large current is applied from the circuit board 5 to the wiring board 1, the cross-sectional area of the current path from the external circuit board 5 including the bonding material 6 such as solder to the wiring board 1 is different between the inner surface electrode 13 and the wiring conductor 14. Since it becomes large in the vicinity of the connection portion, current concentration in the vicinity of the connection portion between the inner surface electrode 13 and the wiring conductor 14 is suppressed, and the connection portion between the inner surface electrode 13 and the wiring conductor 14 is suppressed from being disconnected or high resistance. The electrical connection reliability between the inner surface electrode 13 and the wiring conductor 14 can be improved. When the electronic component 2 is a light emitting element, it can be a wiring board that can emit light satisfactorily. In this case, for example, an opening is provided in the module substrate 5, and the electronic device is joined to the lower surface of the module substrate 5 so as to cover the opening, whereby an electronic module is obtained.

  In addition, since the wiring board 1 can be bonded to the external circuit board 5 by the bonding material 6 such as solder on the upper surface side of the wiring board 1, the thermal conductivity of the entire lower surface side of the wiring board 1 is higher than that of the insulating substrate 11. It is possible to improve the heat dissipation of the wiring board 1 by bonding a member having a high height. As a material having higher thermal conductivity than the insulating base 11, when the insulating base 11 is made of an aluminum oxide sintered body, a metal such as copper (Cu), copper-tungsten (Cu-W) or aluminum (Al) is used. Examples thereof include an insulator made of a material and an aluminum nitride sintered body.

  Similar to the first embodiment, the wiring board 1 of the third embodiment can be suitably used in a small and high-power electronic device, and electrical connection in the wiring board 1 can be favorably achieved. . For example, the electronic component 2 can be suitably used as a small wiring board for mounting a light emitting element on which a high light emitting element is mounted.

The present invention is not limited to the above-described embodiments, and various modifications can be made. In the above-described example, the notch portion 12 and the inner surface electrode 13 are respectively provided on the two opposing side surfaces of the insulating base 11, but the notch 12 and the inner surface electrode 13 are provided on the insulating base 11. The wiring board 1 provided on all four side surfaces or the wiring board 1 provided with a plurality of cutout portions 12 and the inner surface electrode 13 on each side may be used. In the example shown in FIGS. 1 to 14, the insulating base 11 is formed of two or three insulating layers 11a. However, the insulating substrate 11 may be formed of four or more insulating layers 11a.

  Further, as in the example shown in FIG. 13, the wiring board 1 may have conductors other than the wiring, such as the electronic component mounting layer 16 and the central terminal layer 17. For example, these conductors can be manufactured using the same materials and methods as those for the inner surface electrode 13 and the wiring conductor 14 described above, and a plating layer similar to the inner surface electrode 13 and the wiring conductor 14 is deposited on the exposed surface. Has been. The electronic component mounting layer 16 is used for mounting the electronic component 2, for example, and the central terminal layer 17 is used for bonding to the external circuit board 5, for example, similarly to the inner surface electrode 13 and the main surface electrode 13 a. Further, as in the example shown in FIG. 13, the central terminal layer 17 may also be connected to the inner surface electrode 13 provided on the inner surface 12a of the notch portion 12.

  In the above example, one electronic component 2 is mounted on the wiring board 1, but it may be a wiring board 1 on which a plurality of electronic components 2 are mounted.

  Further, the wiring board 1 may be manufactured in the form of a multi-piece wiring board.

1 ... Wiring board
11 ... Insulating substrate
11a ... Insulating layer
12 .... Notch
12a ... Inside surface
13 ... Inner electrode
13a ... Main surface electrode
13b Thick part (inner electrode)
14 ... Wiring conductor
15 ... Cavity
16 ... Electronic component mounting layer
17 ... Central terminal layer 2 ... Electronic component 3 ... Connection member 4 ... Sealing material 5 ... Module board (external circuit board)
51 ··· Connection pad 6 ··· Bonding material

Claims (5)

An insulating base having a notch opening in the main surface and side surfaces;
An inner surface electrode provided on the inner surface of the notch,
A wiring conductor provided in the insulating base and connected to the inner surface electrode at an end opposite to the main surface of the inner surface electrode;
The wiring board according to claim 1, wherein the inner surface electrode is thicker at a connection portion with the wiring conductor.   2. The wiring board according to claim 1, wherein, in a plan view, a portion where the thickness of the inner surface electrode is increased is provided along the inner surface.   The wiring board according to claim 1, wherein the wiring conductor is thick at a connection portion with the inner surface electrode. A wiring board according to claim 1;
An electronic device comprising: an electronic component mounted on the wiring board.   The electronic device according to claim 4 is connected to a connection pad of a module substrate via a bonding material, and the bonding material spreads from the inner end portion of the inner surface electrode to the connection pad. An electronic module characterized by being inclined as described above.

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