JP6367640B2 - Wiring board - Google Patents

Description

  The present invention relates to a wiring board for mounting an element such as a light emitting element having a relatively high heat generation property on a surface pad formed on the surface of a substrate body made of an insulating material.

  For example, it has a mounting portion exposed at the center portion of the surface of the insulating base made of flat ceramic, and a space between the mounting portion and the center portion of the back surface of the insulating base along the vertical direction of the insulating base. Generated from a light emitting element mounted above the mounting portion by providing a flat penetrating metal body penetrating and providing an inclined portion or a stepped portion on the side surface of the penetrating metal body in contact with the ceramic of the insulating base There has been proposed a light-emitting element wiring board excellent in heat dissipation and mounting reliability (see, for example, Patent Document 1).

However, since the area of the through metal body mounting portion (upper surface) exposed on the surface of the insulating base is relatively large in the light emitting element wiring substrate, the vicinity of the through metal body mounting portion and the insulating material adjacent thereto are adjacent to each other. The stress acting due to the difference in thermal expansion coefficient from the ceramic or resin constituting the substrate becomes large. As a result, when an element such as a light emitting element having a relatively large calorific value is mounted above the through metal body mounting portion, the through metal body mounting portion is surrounded by the stress caused by the difference in thermal expansion coefficient. There is a problem that cracks are likely to occur on the ceramic or resin surface side of the insulating substrate.
Furthermore, when the wiring board for light emitting elements is mounted on a surface of a mother board such as a printed board with an inclination in a vertical cross section, the penetrating metal body is also inclined, so that the light emitting element via the penetrating metal body, etc. There is also a problem that the heat dissipating property of the heat may be reduced due to the shift of the heat dissipating direction of the heat generated from the element.
Moreover, in the light emitting element wiring board that penetrates the through metal body through the central portion of the insulating base, when mounted on the surface of the mother board in an inclined posture as described above, the bottom surface of the through metal body and the mounting surface Since the distance between them varies from place to place, there is also a problem that the capacitance of the insulating base easily changes from place to place.

JP 2006-93565 A (pages 1-21 and FIGS. 1-4)

  The present invention solves the problems described in the background art, and even when an element such as a light emitting element having a relatively high exothermic property is mounted on a surface pad formed on the surface of a substrate body made of an insulating material, Providing a wiring board that is less likely to crack in the insulating material in contact with the surface pad, is less likely to deviate the direction of heat dissipation even when mounted on the surface of the mother board and is easy to keep the capacitance of the board body uniform, This is the issue.

Means for Solving the Problems and Effects of the Invention

In order to solve the above-described problem, the present invention provides a heat radiating portion in which one end is connected to the surface pad and the other end is embedded in the substrate body with respect to the area of the surface pad formed on the surface of the substrate body. The idea is to reduce the cross-sectional area of the first connecting portion to be connected and to make the back side of the substrate body in the heat radiating portion spherical.
That is, the wiring board of the present invention (Claim 1) is made of an insulating material, and has a substrate body having a front surface and a back surface parallel to each other, and a side surface located between the front surface and the back surface, and a surface of the substrate body. A wiring board comprising a surface pad formed thereon, a heat radiating part embedded in the substrate body, and a first connecting part for connecting the surface pad and the heat radiating part, wherein the heat radiating part Has a spherical surface at least facing the back surface of the substrate body , and a plurality of sets of grooves and ridges along the direction from the front surface side to the back surface side of the substrate body are formed. The area of the first connection part exposed on the surface of the substrate body is smaller than the area of the surface pad.

According to this, the heat radiating portion is connected to the surface pad formed on the surface of the substrate body via the first connection portion having an area smaller than the area of the surface pad in plan view. That is, in plan view, the area of the first connection portion exposed on the surface of the substrate body is smaller than the area of the surface pad. Therefore, when an element such as a light emitting element having a relatively large calorific value is mounted above the surface pad, heat generated from the element is transmitted to the heat radiating part via the first connection part, and After being sequentially diffused from the surface of the heat dissipating part into the insulating material constituting the substrate body, it is discharged to the outside. For this reason, the occurrence of cracks on the surface side of the insulating material due to the difference in thermal expansion coefficient between the surface pad and the insulating material of the substrate main body in contact therewith is eliminated or reliably suppressed. It becomes possible.
Furthermore, since at least the surface opposite to the back surface of the board body is a spherical surface (semispherical surface), the wiring board is mounted on the surface of a motherboard such as a printed board with an inclination with respect to a vertical line. Even if the heat dissipating part is inclined, the heat dissipating direction from the light emitting element or the like via the heat dissipating part is not easily shifted. Therefore, since the heat radiation path does not change greatly, the same heat radiation performance as in the horizontal posture can be obtained.
Moreover, even when mounted in an inclined position as described above, the distance between the spherical surface of the heat radiating portion and the mounting surface of the motherboard is almost the same as in the horizontal position. The electric capacity hardly changes.
In addition, a plurality of sets of concave grooves and ridges extending from the top side to the bottom side of the heat radiating part are formed on the spherical surface of the heat radiating part, the curved surface or the plurality of side surfaces forming the cone shape. Thus, the surface area of the heat dissipating part is enlarged . Therefore, the heat transmitted from the light emitting element or the like through the first connection portion can be efficiently dissipated into the insulating material of the substrate body, and the adhesion strength between the insulating material and the heat radiating portion can be increased, and the manufacturing can be performed. The filling operation of the conductive paste at the time can be performed smoothly .
Therefore, even if an element with a high calorific value is mounted above the surface pad, the insulating material on the surface layer side of the substrate body in contact with the surface pad is not easily cracked by the heat generated by the element, and the motherboard is inclined. Even if mounted on the wiring board, it is possible to provide a wiring board in which the heat radiation direction is not easily shifted and the electrostatic capacity is stable.

The insulating material constituting the substrate body is ceramic or resin. Examples of the ceramic include high-temperature fired ceramics such as alumina and low-temperature fired ceramics such as glass-alumina. A synthetic resin (for example, epoxy, polyester, silicon, polyimide resin, etc.) that is curable and heat resistant is included.
The surface of the substrate body also includes a bottom surface of a cavity that opens to the surface.
Further, the surface pad is formed to protrude by the thickness outside the surface of the substrate body. On the pad, a light emitting element such as a light emitting diode (LED) or an element having a relatively large amount of heat generation such as a semiconductor element used in a power module is mounted.

In addition, the heat radiating portion is mainly made of a metal having excellent thermal conductivity, and the metal includes W, Mo, Ag, Cu, or an alloy mainly containing any one of these metals. The metal powder for constituting is preferably 1 μm or less in average particle size in order to ensure fluidity during production. However, the heat dissipating part may contain a non-conductive component such as a binder resin included in the conductive paste used at the time of manufacture.
Furthermore, the first connection portion is made of the same metal as the heat dissipation portion, and may have an elliptical shape, an oval shape, a rectangular shape, or a polygonal shape of pentagon or more in addition to a circular cross section.
In addition, the substrate body may be configured such that a plurality of first connection portions and a single or a plurality of heat dissipation portions are electrically connected to one surface pad.

Further, according to the present invention, the heat radiating part has a spherical shape as a whole, or the surface side of the substrate body in the heat radiating part has a large cross-sectional area in plan view from the surface side of the substrate body to the back side. The wiring board (Claim 2) having a conical shape is also included.
Among the above, according to the heat radiating portion having a spherical shape as a whole, the heat radiating direction is difficult to shift, and the stability of the capacitance can be easily ensured. In addition, since the surface area is small with respect to the volume, it is easy to embed in a relatively thin substrate body.
On the other hand, the surface side of the substrate body has a conical shape in which a cross-sectional area in plan view increases from the surface side toward the back surface side, and the surface on the back surface side of the substrate body is in the form of the spherical surface (semispherical surface). According to the heat dissipating part, in addition to the heat dissipating direction and the stability of the electrostatic capacity, the heat transmitted from the first connecting part can be gradually and rapidly transmitted toward the spherical surface side.
In addition, the cone shape of the surface side in the said thermal radiation part is a cone shape or a polygonal pyramid shape.

Furthermore, in the present invention, one end of a second connection portion with the other end exposed at the back surface or side surface of the substrate body is connected to the spherical surface of the heat radiating portion facing the back surface of the substrate body. (Claim 3 ) is also included .

According to which this first connecting portion, the heat radiating portion, and via a second connecting portion, and electrically conductively between or between the surface and the side surface, the surface and the back surface of the substrate body . Therefore, for example, one electrode in a light emitting element or the like mounted above the front surface pad is electrically connected to a back surface pad or a side conductor formed on the back surface or side surface of the substrate body. It becomes possible. In addition, the electrode of the element and a surface pad such as a mother board on which the wiring board itself is mounted can be electrically connected through the heat radiating portion and the back surface pad or the side conductor. Furthermore, the heat generated by the element can be released to the outside of the substrate body through the back pad or the side conductor.

The second connecting portion is also made of the same metal as the first connecting portion and the heat radiating portion, and has the same form as the first connecting portion, and the first connection with respect to the back surface or side surface of the substrate body. It is arranged in the same way as the section.
Further, on the back surface or side surface of the substrate body where the other end of the second connection portion is exposed, a back surface pad or a side conductor connected individually to these is formed.
Further, the second connection portion may extend from the bottom surface side of the heat radiating portion having a cone shape to both the back surface and the side surface of the substrate body.

1 is a vertical sectional view showing a wiring board according to an embodiment of the present invention. (A) is a perspective view which shows the thermal radiation part vicinity used for the said wiring board, (B) is a perspective view which shows the thermal radiation part vicinity of a different form. (A), (B) is the schematic which shows the manufacturing process of the said wiring board, respectively. (A), (B) is the schematic which shows the manufacturing process following FIG. 3 (B). (A), (B) is the schematic which shows the manufacturing process following FIG. 4 (B). FIG. 3 is a vertical sectional view showing a usage state of the wiring board. (A), (B) is a perspective view which shows the thermal radiation part vicinity of a further different form, respectively. (A), (B) is a vertical sectional view which shows the wiring board of a different form, respectively. (A), (B) is a perspective view which shows the thermal radiation part vicinity of an application form, respectively.

Hereinafter, modes for carrying out the present invention will be described.
FIG. 1 is a vertical sectional view showing a wiring board 1a according to an embodiment of the present invention, and FIG. 2A is a perspective view showing the vicinity of a heat radiation part 8a embedded in the wiring board 1a.
As shown in FIG. 1, the wiring board 1 a is made of, for example, ceramic (insulating material) such as glass-ceramic, and is positioned between the front surface 3 and the back surface 4 parallel to each other and the periphery of the front surface 3 and the back surface 4. A substrate body 2 having four side surfaces 5, a surface pad 6 formed on the surface 3 of the substrate body 2, and a heat radiating portion 8 a embedded in the substrate body 2.
As shown in FIGS. 1 and 2 (A), the entire heat radiating portion 8a has a spherical shape 9, and the surface facing the back surface 4 side of the substrate body is also a spherical surface (semispherical surface) 9a. Above and below the heat radiating portion 8a, a first connecting portion 11 and a second connecting portion 12 having a circular cross section are coaxially connected to a vertical line (virtual) penetrating the central portion of the heat radiating portion 8a. Yes.

As shown in FIG. 1, the first connection portion 11 has an upper end exposed in the vicinity of the center portion of the surface 3 of the substrate body 2 and is connected to the bottom surface of the surface pad 6. The second connection portion 12 has a lower end exposed near the center of the back surface 4 of the substrate body 2 and is connected to the top surface of the back pad 7 formed on the back surface 4.
In FIG. 1, the central axes of the first connection portion 11 and the second connection portion 12 are orthogonal to the front surface 3 and the back surface 4 of the substrate body 2, respectively, but are not necessarily limited to this form. .
Further, an elongated columnar via conductor 20 penetrating between the front surface 3 and the back surface 4 is disposed at any one of the peripheral portions of the front surface 3 and the back surface 4 of the substrate body 2, and the upper end portion of the via conductor 20 is disposed. The surface electrode 21 formed on the front surface 3 is connected, and the lower surface of the via conductor 20 is connected to the back electrode 22 formed on the back surface 4.
As shown in FIG. 1, the surface electrode 21 is electrically connected to one electrode of a light emitting element 24 mounted on the surface pad 6 later via a bonding wire 23. On the other hand, the back pad 7 and the back electrode 22 can be electrically connected to an external terminal on the mother board (not shown) on which the wiring board 1a is mounted.

In addition, as shown in FIG. 2 (B), a surface facing the back surface 4 side of the substrate body 2 is provided between the first connecting portion 11 and the second connecting portion 12 instead of the heat radiating portion 8a. A surface that is a spherical surface (hemispherical surface) 9a and faces the surface 3 side of the substrate body 2 is a semi-elliptical sphere-shaped portion 10 that has an oval shape in a side view, and the heat radiating portion 8b that has an oval shape overall is You may arrange | position coaxially with the central axis of the 1st connection part 11 and the 2nd connection part 12. FIG. In this form, the 1st connection part 11 is standingly arranged from the top part 13 of the thermal radiation part 8b.
The front and back pads 6 and 7, the heat radiating portions 8 a and 8 b, the first and second connecting portions 11 and 12, the via conductor 20, and the front and back electrodes 21 and 22 are made of ceramic constituting the substrate body 2. In the case of a low-temperature fired ceramic such as glass-ceramic, it is mainly composed of Ag or Cu, and in the case where the ceramic is a high-temperature fired ceramic such as alumina, it is mainly composed of W or Mo.

Below, the manufacturing method of the said wiring board 1a is demonstrated.
As shown in the vertical cross-sectional view of FIG. 3A in advance, in order to form the heat radiating part 8a having the first connecting part 11 and the second connecting part 12 in the upper and lower sides, a model part 9p having a similar shape to these parts. , 11p, 12p, and a solid model 20m similar to the via conductor 20 were manufactured.
That is, by using a liquid raw material made of an acrylic resin powder and an adhesive having an average particle diameter of 1 to 50 μm in a three-dimensional printer (not shown), as shown in FIG. A three-dimensional model 8m including 11p and 12p and a model part 8p for the heat radiation part 8a sandwiched between them and having a spherical shape as a whole was formed.
Further, by using the raw material and the three-dimensional printer, a three-dimensional model 20m similar to the via conductor 20 was formed as shown on the right side of FIG.

Next, the three-dimensional models 8m and 20m are placed in a rectangular parallelepiped cavity disposed in a mold (not shown), with only the upper and lower end surfaces in contact with and constrained to the ceiling surface and floor surface of the cavity. The above-mentioned cavity was filled with a glass-ceramic (insulating material) slurry by a gel casting method.
As a result, as shown in FIG. 3B, the slurry is made of a dried (unfired) ceramic body, has a front surface 3, a back surface 4, and a side surface 5 located between these four sides, An unfired base substrate body 30 was obtained in which both end faces of the model portions 11p, 12p, and 20m of the model 8m were individually exposed on the front surface 3 and the back surface 4.
Next, the base substrate body 30 was heated to a predetermined temperature range, and the glass-ceramic constituting the base substrate body 30 was fired. In this heating process, the acrylic resin powder, adhesive, and the like constituting the three-dimensional models 8m and 20m were sequentially evaporated to the outside from the upper end side of each of the three-dimensional models 8m and 20m.

As a result, as shown in FIG. 4 (A), it is made of the glass-ceramic, has a front surface 3, a back surface 4, and a side surface 5 located between these four sides, and the three-dimensional models 8m and 20m are evaporated. The removed trace shows a substrate made of fired ceramic in which a three-dimensional cavity portion 8s and a cavity portion 20s each having a hollow portion 9s, 11s, and 12s similar to the three-dimensional model 8m and 20m are formed inside. A main body 31 was obtained.
Further, a conductive paste containing Ag powder or Cu powder (metal powder) was filled from the upper end portion (opening portion) on the surface 3 side in each of the hollow portions 8s and 20s.
As a result, as shown in FIG. 4B, a three-dimensional structure comprising uncured first and second connection portions 11u, 12u made of the conductive paste and uncured heat dissipation portion 9u in the cavity 8s. The substrate body 2 was obtained in which the conductor portion 8u was formed and the uncured via conductor 20u made of the conductive paste was formed in the hollow portion 20s.
In addition, since the conductive paste was filled into the hollow portion 9s similar to the spherical model portion 9p inside and around the heat radiating portion 9u, no gap was generated.

Next, by heating the substrate body 2 in which the uncured first and second connection portions 11u and 12u, the heat radiating portion 9u, and the via conductor 20u are provided to a predetermined temperature zone, the heat radiating portion 8u and the via conductor 20p were cured (cured). As a result, as shown in FIG. 5A, the substrate body in which the spherical heat dissipation portion 8a having the hardened first and second connection portions 11 and 12 on the upper and lower sides and the via conductor 20 are embedded therein. 2 was obtained.
After the front surface 3 and the back surface 4 of the substrate body 2 are polished, the vicinity of the end surfaces of the first and second connecting portions 11 and 12 exposed on the front surface 3 and the back surface 4 and the vicinity of both end surfaces of the via conductor 20 On the other hand, a Ti alloy is sputtered to form a base metal layer having a rectangular or circular shape in plan view, Cu is sputtered on the surface of each base metal layer, and a surface metal layer is laminated to form a pad body. Then, electrolytic Ni plating and electrolytic Au plating were sequentially applied to the surfaces, and a Ni plating film and an Au plating film (not shown) were coated in two layers.

As a result, as shown in FIG. 5B, the first and second connecting portions 11 and 12, the heat radiating portion 8a, and the via conductor 20 are embedded in the substrate body 2, and the first and second connecting portions are embedded. 2 The front and back pads 6 and 7 connected individually for each end face of the connecting portions 11 and 12 and the front and back electrodes 21 and 22 connected individually to both end faces of the via conductor 20 are connected to the front face 3 or the back face 4. The wiring board 1a formed in (1) was obtained.
In addition, the wiring board 1a which embed | buries the said heat radiating part 8b in the inside of the board | substrate body 2 similarly to the above can also be manufactured by changing the shape of the said model part 9p.
According to the manufacturing method as described above, it is possible to manufacture the wiring substrate 1a precisely and reliably with relatively few steps, whether it is a single piece or a multi-piece method.

  According to the wiring substrate 1a as described above, the heat radiating portions 8a and 8b, which have a spherical shape or an egg shape as a whole, are provided on the surface pad 6 formed on the surface 3 of the substrate body 2 in a plan view. The first connection part 8 having an area smaller than the area 6 is connected. That is, in plan view, the area of the first connection portion 8 exposed on the surface 3 of the substrate body 2 is smaller than the area of the surface pad 6. Therefore, when the light emitting element 24 having a relatively large calorific value is mounted above the surface pad 6 later, the heat generated from the element 24 is transmitted to the heat radiating parts 8a and 8b via the first connection part 11. Then, after being sequentially dissipated from the surface of the heat radiating portions 8a and 8b into the glass-ceramic constituting the substrate body 2, it is discharged to the outside. Therefore, there is a situation in which cracks are generated on the surface 3 side of the substrate body 2 due to the difference in thermal expansion coefficient between the surface pad 6 and the glass-ceramic constituting the surface 3 of the substrate body 2 in contact therewith. It can be eliminated or at least reliably suppressed.

  Furthermore, since at least the surface facing the back surface 4 of the substrate main body 2 is a spherical surface (semispherical surface) 9a, the heat radiation portions 8a and 8b are, for example, as shown in FIG. When the back electrode 22 is connected to the external terminal 27 formed on the surface of the printed board 26 via the solder 28, the wiring board 1a is mounted in an inclined state, and the heat radiating portions 8a and 8b are inclined. Even if it becomes, it becomes difficult to shift | deviate the heat radiation direction of the heat from the light emitting element 24 via this heat radiating part 8a, 8b. As a result, since the heat radiation path does not change greatly, the same heat radiation performance as in the horizontal posture can be obtained. In FIG. 6, the back electrode 22 on the left side is a dummy electrode that is not connected to the internal conductor.

Moreover, even when mounted in an inclined posture as described above, the distance between the spherical surface 9a of the heat radiating portions 8a and 8b and the mounting surface of the printed circuit board 26 is substantially the same as that in the horizontal posture. The capacitance at the site is hardly changed.
Therefore, even if a light emitting element 24 or the like that generates a large amount of heat is mounted on the surface pad 6 later, the ceramic on the surface 3 side of the substrate body 2 in contact with the surface pad 6 is cracked by the heat generated by the element 24. In addition, it is possible to provide the wiring board 1a in which the heat dissipation direction is not easily shifted and the capacitance is stable even when mounted on the surface of the motherboard in an inclined posture.

FIG. 7A is a perspective view showing the vicinity of the heat radiation part 8c having a different form from the above.
As shown in FIG. 7A, the heat dissipating part 8c has a spherical surface (semispherical surface) 9a that is the same as the heat dissipating part 8a, and the surface 3 of the substrate main body 2 is opposite to the back surface 4 of the substrate main body 2. The confronting surface is a conical surface (conical shape) 14 whose area in plan view increases from the front surface 3 side to the back surface 4 side, and the top 15 of the conical surface 14 has the first connecting portion 11. The lower end is connected in a coaxial shape.
FIG. 7B is a perspective view showing the vicinity of the heat radiating portion 8d of a further different form.
As shown in FIG. 7B, the heat dissipating part 8d has a spherical surface (semispherical surface) 9a which is the same as the heat dissipating part 8a, and the surface 3 of the substrate main body 2 is opposite to the back surface 4 of the substrate main body 2. Is a quadrangular pyramid surface (cone shape) 16 whose area in plan view increases from the front surface 3 side toward the back surface 4 side, and the first connection to the top portion 16a of the quadrangular pyramid surface 16 The lower end of the part 11 is connected in a coaxial shape. The quadrangular pyramid surface 16 is composed of four side surfaces 17. The quadrangular pyramid surface 16 may be a pentagonal pyramid surface, a hexagonal pyramid surface, or an octagonal pyramid surface.
The heat dissipating parts 8c and 8d as described above can be embedded in the substrate body 2 of the wiring board 1a in the same manner as described above, instead of the heat dissipating part 8a.

FIG. 8A is a vertical cross-sectional view showing an outline of a wiring board 1b having a different form.
As shown in FIG. 8A, the wiring substrate 1b includes the same substrate body 2, surface pad 6, first connection portion 11, and heat dissipation portion 8a as described above. The wiring board 1b does not have the second connection part 12 between the lowest part of the spherical surface 9a of the heat radiating part 8a and the back surface 4 of the board body 2, but a pair of via conductors in the peripheral part of the board body 2 20 is symmetrically penetrated, and the front surface electrode 21 and the back surface electrode 22 are individually connected to both ends thereof.
As shown in FIG. 8A, a semiconductor element 25 that generates a relatively large amount of heat is mounted on the surface pad 6, and a pair of external electrodes (not shown) in the element 25 and left and right The pair of surface electrodes 21 are electrically connected individually via bonding wires 23.

According to the wiring board 1b as described above, cracks are unlikely to occur in the ceramic on the surface 3 side similar to the wiring board 1a, and the heat generated from the semiconductor element 25 causes the surface pad 6 and the first connection portion 11 to be generated. Then, it is diffused to the heat radiating portion 8a, diffused to the ceramic constituting the substrate body 2, and then released to the outside. Moreover, the semiconductor element 25 includes a motherboard (not shown) such as a printed board on which the wiring board 1b is mounted via the bonding wires 23, a pair of via conductors 20 penetrating the board body 2, and the back electrode 22. ) Can be conducted, so that the required operation can be reliably performed. Furthermore, since only the pair of back surface electrodes 22 are formed on the back surface 4 of the substrate body 2, the positions where they should be arranged can be designed relatively freely.
The heat radiating portion 8a embedded in the substrate body 2 of the wiring board 1b may be replaced with any of the heat radiating portions 8b to 8d.

FIG. 8B is a vertical cross-sectional view showing a further different form of the wiring board 1c.
As shown in FIG. 8B, the wiring substrate 1c includes the same substrate body 2, surface pad 6, first connection portion 11, heat radiating portion 8a, via conductor 20, and front and back electrodes 21, 22 as described above. I have. The wiring board 1 c does not have the second connection part 12 and the back surface pad 7, but the other end of the spherical surface 9 a of the heat radiating part 8 a is exposed to the side surface 5 of the board body 2 and One end of the second connection portion 12a parallel to the surface 3 is connected. A side conductor 18 is formed on the side surface 5 of the substrate body 2 where the other end of the second connection portion 12a is exposed, and a lower end portion of the side conductor 18 is formed on the peripheral side of the back surface 4 of the substrate body 2. The back surface pad 19 is connected.
The wiring board 1c can also achieve the same effects as the wiring board 1a.
The heat dissipating part 8a embedded in the substrate body 2 of the wiring board 1c may be replaced with any of the heat dissipating parts 8b to 8d.
The second connection portion 12a may be inclined obliquely downward from the spherical surface 9a side to the side surface 5 side.
Further, in addition to the second connection portion 12a and the side conductor 18, the wiring board 1c may further include the second connection portion 12 and the back surface pad 7.

FIG. 9A is a perspective view showing the vicinity of the heat radiating portion 8a of the applied form.
As shown in FIG. 9A, the heat radiating portion 8a has a plurality of surfaces along the direction (vertical direction) from the surface 3 side to the back surface 4 side of the substrate body 2 on the surface of the sphere 9 including the spherical surface 9a. The set of concave grooves 32 and ridges 33 are continuously formed along a circumferential direction orthogonal to the above direction. The groove 32 and the ridge 33 are completely absent on the first connection portion 11 and the second connection portion 12 side, and the groove 32 is deepest at an intermediate position between the first connection portion 11 and the second connection portion 12. And the ridge 33 is the highest.
By further forming the plurality of sets of concave grooves 32, 33 on the entire spherical shape 9, the surface area of the heat radiating portion 8a is further increased, so that the contact area with the ceramic constituting the substrate body 2 is increased. It becomes possible to dissipate heat from the light emitting element 24 or the semiconductor element 25 more efficiently into the ceramic of the substrate body 2. In addition, the filling of the conductive paste into the hollow portion during production does not cause any trouble.
The plurality of sets of concave grooves 32 and 33 may be formed in the same manner as described above with respect to the spherical surface 9a and the semi-elliptical spherical shape portion 10 of the heat radiating portion 8b.

FIG. 9B is a perspective view showing the vicinity of the heat radiating portion 8c of the applied form.
As shown in FIG. 9B, the heat radiating portion 8 c includes a plurality of sets of concave grooves 34 and ridges 35 along the direction from the front surface 3 side to the rear surface 4 side of the substrate body 2 in the conical surface 14. It is formed continuously. The plurality of sets of concave grooves 34 and ridges 35 may be continuously formed on the side of the spherical surface 9 a facing the back surface 4 of the substrate body 2 along the same direction as described above.
By forming the plurality of sets of concave grooves 34 and 35 on the conical surface 14 and also on the spherical surface 9a, the surface area of the heat radiating portion 8c is further increased, and the contact area with the ceramic constituting the substrate body 2 is increased. And the heat from the light emitting element 24 and the like can be dissipated more efficiently into the ceramic of the substrate body 2. In addition, the filling of the conductive paste into the hollow portion during production does not cause any trouble.
The plurality of sets of concave grooves 34 and 35 may be formed in the same manner as described above with respect to the conical surface 14 of the heat radiating portion 8c and the quadrangular pyramid surface 16 of the heat radiating portion 8d.

The present invention is not limited to the embodiments described above.
For example, the insulating material constituting the substrate body 2 may be a low-temperature fired ceramic other than glass-ceramic or a high-temperature fired ceramic such as alumina. In the latter case, W or Mo is applied to the heat radiating portions 8a to 8d, the via conductor 20, and the like. Further, a thermosetting and heat resistant synthetic resin (for example, an epoxy resin) may be applied to the insulating material.
The substrate body has a cavity having an opening at the center of the surface thereof, one end portion of the first connection portion 11 is exposed on the bottom surface (surface) of the cavity, and the surface pad 6 is provided directly above the bottom surface. You may connect and form.

In addition, a plurality of the heat radiating portions may be embedded in a single substrate body, the first connecting portions may be connected to the plurality of heat radiating portions, and the second connecting portions may be further connected. .
Further, in the heat radiating portion, the conical shape of the portion excluding the spherical surface has, for example, a horizontal flat circular surface or a square top surface (top portion) on the first connection portion side, and a vertical cross section is a trapezoid. It is good also as a form which is a shape and the whole exhibits a cone shape or a square pyramid shape.
Moreover, in the case of the heat radiating part including a pyramid shape having a horizontal and flat circular surface or a square top surface, a plurality of first connection portions may be connected to the top surface.
In addition, a plurality of second connection portions inclined symmetrically to each other may be disposed between the spherical surface 9 a of the heat generating portions 8 a to 8 d and the back surface 4 of the substrate body 2.

  According to the present invention, even when an element such as a light emitting element having relatively high heat generation is mounted on a surface pad formed on the surface of a substrate body made of an insulating material such as ceramic, the element is adjacent to the periphery of the surface pad. Even when the insulating material is hardly cracked and mounted on the surface of the mother board at an inclination, it is possible to provide a wiring board in which the heat radiation direction is difficult to shift and the electrostatic capacity of the board main body is easily maintained.

1a to 1c ………………………… Wiring board 2 …………………………………… Board body 3 …………………………………… Surface 4… ………………………………… Back 5 …………………………………… Side 6 …………………………………… Front Pad 11 …… …………………………… 1st connection part 12,12a ……………………… 2nd connection part 8a ~ 8d ………………………… Heat dissipation part 9 ……… …………………………… Spherical shape 9a ………………………………… Spherical surface 10, 14, 16 ………………… Cone shape 32, 33 …………… …………… Projections 34, 35 …………………………

Claims (3)

A substrate body made of an insulating material, having a front surface and a back surface parallel to each other, and a side surface located between the front surface and the back surface;
A surface pad formed on the surface of the substrate body;
A heat dissipating part embedded in the substrate body;
A wiring board comprising a first connection part for connecting the surface pad and the heat dissipation part,
The heat dissipating part has a spherical surface at least facing the back surface of the substrate body , and a plurality of sets of concave grooves and ridges along the direction from the front surface side to the back surface side of the substrate body. ,
In plan view, the area of the first connection portion exposed on the surface of the substrate body is smaller than the area of the surface pad.
A wiring board characterized by that. The heat dissipating part has a spherical shape as a whole, or the surface side of the substrate main body in the heat dissipating part has a conical shape in which a cross-sectional area in plan view increases from the front surface side to the back surface side of the substrate main body.
The wiring board according to claim 1. One end of a second connection portion with the other end exposed at the back surface or side surface of the substrate body is connected to the spherical surface of the heat radiating portion facing the back surface of the substrate body.
The wiring board according to claim 1 or 2, wherein

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