JP7564024B2 - Wiring Board - Google Patents

Description

The present invention relates to a wiring board.

Conventionally, wiring boards with high heat dissipation properties have been used as wiring boards on which elements that generate a lot of heat, such as LEDs (light emitting diodes) and power semiconductors, are mounted. A technology has been proposed for high heat dissipation wiring boards in which an aluminum substrate is coated with an anodized aluminum film to be used as an electronic substrate (hereinafter also referred to as an anodized substrate). An anodized substrate is insulating while maintaining the thermal conductivity and thermal diffusivity of the aluminum substrate, allowing for high heat dissipation.

By the way, wiring boards may be manufactured in the form of a so-called multi-cavity wiring board, in which multiple wiring board regions on which electronic components are mounted are formed. In the case of a multi-cavity wiring board, a single multi-cavity wiring board is diced to obtain multiple pieces. Since anodized coatings are prone to cracking, when anodized boards are manufactured in a multi-cavity form, the impact of cutting makes it easy for cracks to form in the anodized coating. In response to this issue, for example, Patent Document 1 proposes a technology that suppresses the occurrence of cracks that occur during dicing by forming the boundaries between adjacent wiring board regions (pieces) by punching before forming the anodized coating, and reducing the area in which the tie bars connecting the adjacent wiring board regions are formed.

Patent No. 6008204

However, in the technology described in Patent Document 1, the surface of the tie bar is coated with an anodized aluminum film, so even with the technology described in Patent Document 1, there is still a risk of cracks occurring during dicing.

The present invention has been made to solve the above-mentioned problems, and aims to provide another technology for suppressing the occurrence of cracks in an oxide film layer in a wiring board having a substrate made of a metal material mainly composed of aluminum and an oxide film layer formed on the substrate surface.

The present invention has been made to solve the above-mentioned problems, and can be realized in the following forms:

(1) According to one aspect of the present invention, there is provided a wiring board comprising: a base material made of a metal material mainly composed of aluminum (Al), and an oxide coating layer which is an anodized coating of the metal material formed on a surface of the base material and has a conductive wiring portion formed on an upper surface thereof, the oxide coating layers being spaced apart from each other in a plan view, and the surface of the base material being exposed between adjacent oxide coating layers.

This type of wiring board is a so-called multi-piece wiring board, and each area where one oxide layer is formed corresponds to one piece. With this configuration, multiple oxide layers are formed at a distance from each other, and the substrate surface is exposed between adjacent oxide layers. Therefore, when cutting the multi-piece wiring board into individual pieces, the substrate made of a metal material is cut, but the oxide layer is not cut, so that the occurrence of cracks in the oxide layer can be suppressed.

(2) In the wiring board of the above embodiment, the combined area of the multiple oxide film layers on the surface of the substrate on which the multiple oxide film layers are formed may be greater than the combined area of the exposed portion where the substrate is exposed. In this way, the number of individual pieces can be increased.

(3) In the wiring board of the above embodiment, three or more of the oxide coating layers may be formed and arranged vertically and horizontally, which makes it easy to dice the wiring board into individual pieces.

(4) In the wiring board of the above embodiment, the outer periphery of the oxide coating layer may be such that the surface of the substrate is exposed over the entire circumference in a plan view. If the oxide coating layer is formed on a protruding portion such as a corner of the substrate, it is highly likely that the oxide coating layer will become a starting point of cracks due to heating or impact. According to this embodiment, since the oxide coating layer is not formed on the peripheral portion of the wiring board, cracks in the oxide coating layer can be further suppressed. Furthermore, even when the wiring board is diced into individual pieces, since the oxide coating layer is not formed on the edges or corners of the substrate, the occurrence of cracks in the individual pieces can also be suppressed.

The present invention can be realized in various forms, such as a product including a wiring board, a method for manufacturing a wiring board, and a method for manufacturing a product including a wiring board.

FIG. 2 is an explanatory diagram illustrating a planar configuration of the wiring board according to the first embodiment; FIG. 2 is an explanatory diagram illustrating a schematic cross-sectional configuration of the wiring board according to the first embodiment. 3A and 3B are explanatory diagrams of individual pieces cut out from the wiring board of the first embodiment. FIG. 13 is an explanatory diagram illustrating a schematic planar configuration of a wiring board according to a second embodiment. FIG. 13 is an explanatory diagram illustrating a schematic configuration of a wiring board according to a third embodiment. FIG. 13 is an explanatory diagram illustrating a schematic configuration of a wiring board according to a fourth embodiment.

First Embodiment
FIG. 1 is an explanatory diagram that shows a schematic planar configuration of a wiring board 100 according to a first embodiment of the present invention, and FIG. 2 is an explanatory diagram that shows a schematic cross-sectional configuration of the wiring board 100. FIG. 2 shows a cross section A-A in FIG. 1. The wiring board 100 has a flat substrate 10 having a substantially rectangular planar shape, an oxide coating layer 20 formed on the surface of the substrate 10, and a first oxide coating layer 21. A wiring portion 30 is formed on the oxide coating layer 20. On the other hand, the wiring portion 30 is not formed on the first oxide coating layer 21, and the first oxide coating layer 21 has a power supply portion 23 that exposes the surface of the substrate 10. The wiring board 100 of this embodiment is a so-called multi-cavity wiring board in which a plurality of oxide coating layers 20 are formed as wiring board regions on which electronic components are mounted.

The substrate 10 is made of a metal material whose main component is aluminum (Al). Since the substrate 10 is made of a metal material whose main component is aluminum, it has high thermal conductivity and thermal diffusivity. In this embodiment, the main component is the component with the highest mass percentage.

As shown in FIG. 2, the substrate 10 is flat and includes a first main surface 11, a second main surface 12 that is the reverse side of the first main surface 11, and a side surface 13 that connects the first main surface 11 and the second main surface 12. In this embodiment, an oxide coating layer 20 and a first oxide coating layer 21 are formed on the first main surface 11 of the substrate 10, and the oxide coating layer 20 and the first oxide coating layer 21 are not formed on the second main surface 12 and the side surface 13.

The oxide coating layer 20 and the first oxide coating layer 21 are anodized coatings (anodized aluminum) formed by anodizing a flat plate (hereinafter also referred to as the "original plate") made of a metal material mainly composed of aluminum to alter its surface. That is, in this embodiment, the anodized coating portion formed by anodizing the original plate is the oxide coating layer 20 and the first oxide coating layer 21, and the unaltered base portion is the substrate 10. The oxide coating layer 20 and the first oxide coating layer 21 are insulating.

As shown in FIG. 1, the oxide layer 20 has a planar shape of a rounded square, in other words, a square with rounded corners. The wiring section 30 is formed on the oxide layer 20, and the oxide layer 20 is the area where electronic components are mounted (hereinafter also referred to as the product area).

The wiring section 30 is constructed by laminating three types of metal thin films whose main components are different from each other. Specifically, a metal thin film whose main component is titanium (Ti), a metal thin film whose main component is platinum (Pt), and a metal thin film whose main component is gold (Au) are laminated in this order from the oxide film layer 20 side. Titanium has good adhesion to the oxide film layer 20, platinum has better adhesion to gold than titanium, and gold has high conductivity, corrosion resistance, and good bonding properties. Therefore, according to this configuration, peeling of the wiring section 30 is suppressed, and a wiring layer that is highly conductive, corrosion resistant, and has good bonding properties can be realized. Note that in FIG. 2, each thin film is not shown separately. The wiring section 30 can be formed by a known method such as vapor deposition or sputtering.

As shown in FIG. 1, the first oxide layer 21 has a rectangular planar shape. The wiring portion 30 is not formed on the first oxide layer 21, and the first oxide layer 21 is not an area on which electronic components are mounted. As described above, the first oxide layer 21 has the power supply portion 23 where the first main surface 11 of the substrate 10 is exposed. The power supply portion 23 is a contact point with the current-carrying jig when performing the above-mentioned anodizing process, and the surface of the substrate 10 is exposed even after the anodizing process is performed. The power supply portion 23 is a through hole (FIG. 2) with a planar shape of a perfect circle (FIG. 1). The planar shape of the power supply portion 23 does not have to be a perfect circle, and may be various shapes such as an approximately elliptical shape or an approximately polygonal shape. The power supply portion is also called an electrode mark, a current-carrying mark, or a jig mark for carrying electricity. In the wiring board 100, two first oxide layers 21 are formed on the ends of the first main surface 11 of the substrate 10.

As shown in FIG. 1, the wiring board 100 has a plurality of oxide coating layers 20 (16 in this embodiment), and the 16 oxide coating layers 20 are arranged vertically and horizontally (specifically, 4 rows and 4 columns). In other words, the 16 oxide coating layers 20 are formed in a checkerboard pattern. As shown in FIGS. 1 and 2, the plurality of oxide coating layers 20 are formed spaced apart from each other in a plan view, and the first main surface 11 of the substrate 10 is exposed between adjacent oxide coating layers 20. That is, the plurality of oxide coating layers 20 are not connected to each other. In addition, the oxide coating layer 20 and the first oxide coating layer 21 are also formed spaced apart from each other, and the first main surface 11 of the substrate 10 is exposed between the oxide coating layer 20 and the first oxide coating layer 21. The portion where the first main surface 11 of the substrate 10 is exposed is hereinafter also referred to as the "exposed portion 15". In FIG. 1, the exposed portion 15 is shown with diagonal hatching.

Figure 3 is an explanatory diagram of individual pieces 110 cut out from the wiring board 100. Figure 3(A) shows the cutting line L when dividing the wiring board 100 into individual pieces 110, and Figure 3(B) shows an example of an individual piece 110. Figure 3(B) illustrates the individual piece at the upper left of the page in Figure 3(A). When the wiring board 100 is divided along the cutting line L (Figure 3(A)), 16 individual pieces 110 (Figure 3(B)) are obtained, each having one oxide layer 20 formed on the surface of the base material 10. The size and arrangement of the exposed portion 15 in each of the 16 individual pieces 110 may be different.

As shown in the figure, the cutting line L is located on the exposed portion 15. In other words, the oxide layer 20 is not formed on the cutting line L. Therefore, when cutting the wiring board 100 into individual pieces 110, the metal plate, which is the base material 10, is cut, and the oxide layer 20 is not cut. This makes it possible to prevent the oxide layer 20 from being damaged and cracked during dicing. As a result, the occurrence of cracks in each individual piece 110 can be suppressed.

Also, as shown in the figure, the oxide coating layer 20 is not formed on the periphery of the wiring board 100. That is, the oxide coating layer 20 is formed away from the end (edge, corner) of the substrate 10, which is likely to become the starting point of cracks due to heating or impact, and the substrate 10 is exposed at the periphery of the wiring board 100. Therefore, cracks in the oxide coating layer 20 can be suppressed. In addition, the first main surface 11 of the substrate 10 is exposed all around the periphery of each oxide coating layer 20, and even in the state of the individual pieces 110 in which the wiring board 100 is diced, the oxide coating layer 20 is formed away from the end (edge, corner) of the substrate 10 (FIG. 3(B)), so the occurrence of cracks in the individual pieces 110 can also be suppressed.

As described above, the first oxide coating layer 21 has the power supply portion 23, and therefore cracks are likely to occur starting from the power supply portion 23. In this embodiment, as described above, the oxide coating layer 20 and the first oxide coating layer 21 are provided at a distance from each other, and the first main surface 11 of the substrate 10 is exposed between the oxide coating layer 20 and the first oxide coating layer 21. Therefore, even if a crack occurs in the first oxide coating layer 21 and progresses, the progress of the crack is stopped at the exposed portion 15, and the crack does not progress to the oxide coating layer 20. Therefore, the wiring portion 30 is formed, and cracks in the oxide coating layer 20, which is the product area, can be suppressed.

In the wiring board 100, the combined area of the multiple oxide coating layers 20 is greater than the combined area of the exposed portions 15. Therefore, many individual pieces can be obtained from one wiring board 100.

In the wiring board 100, a plurality of oxide coating layers 20 are formed at a distance from each other, and the oxide coating layers 20 and the first oxide coating layer 21 are formed at a distance from each other. In this way, as a method for partially forming an oxide coating on the surface of the substrate 10, for example, a method (first method) can be used in which anodizing is formed on the entire surface of the original plate, and then unnecessary parts (parts that expose the surface of the substrate 10) are removed by wet chemical processing, laser processing, or the like. In addition, for example, a method (second method) can be used in which unnecessary parts of the surface of the original plate (parts that expose the surface of the substrate 10) are masked by photolithography and then anodizing is formed.

When the oxide layer 20 and the first oxide layer 21 are formed by the first method, the thickness of the substrate 10 is approximately uniform and is thinner than the thickness of the original plate. On the other hand, when the oxide layer 20 and the first oxide layer 21 are formed by the second method, the thickness of the substrate 10 at the exposed portion 15 (shown with diagonal hatching in FIG. 1) where the first main surface 11 of the substrate 10 is exposed is approximately the same as the thickness of the original plate, and the portion where the oxide layer 20 and the first oxide layer 21 are formed is thinner than the exposed portion 15. In other words, when the oxide layer 20 and the first oxide layer 21 are formed by the second method, the thickness of the substrate 10 differs in parts.

As described above, according to the wiring board 100 of this embodiment, the oxide film layers 20 are formed spaced apart from each other in a plan view, and between adjacent oxide film layers 20, there is an exposed portion 15 where the first main surface 11 of the base material 10 is exposed. Therefore, by cutting the wiring board 100 at the exposed portion 15 when dividing it into pieces 110, the oxide film layer 20 is not cut, so that the occurrence of cracks in the oxide film layer 20 can be suppressed. In other words, the occurrence of cracks in the pieces 110 can be suppressed. In addition, according to the wiring board 100 of this embodiment, since the oxide film layer 20 is not cut when dividing into pieces, roughness of the end surface of the oxide film layer 20 can be suppressed compared to the case where the oxide film is cut when dividing into pieces.

In addition, in the wiring board 100, the oxide coating layer 20 is formed apart from the first oxide coating layer 21, and between the oxide coating layer 20 and the first oxide coating layer 21 is an exposed portion 15 where the first main surface 11 of the substrate 10 is exposed. In other words, since the first oxide coating layer 21, which is prone to cracks starting from the power supply portion 23, is separated from the oxide coating layer 20, even if a crack occurs in the first oxide coating layer 21 and progresses, the progress of the crack is stopped at the exposed portion 15 and does not progress to the oxide coating layer 20. Therefore, the occurrence of cracks in the oxide coating layer 20 can be suppressed.

As described above, when the oxide coating layer 20 is formed on the ends (edges, corners) of the substrate 10, cracks are likely to occur. This is because the oxide coating layer 20 formed on the ends of the substrate 10 has an uneven thickness, and stress is likely to concentrate at the ends of the substrate 10. In contrast, according to the wiring board 100 of this embodiment, the oxide coating layer 20 is not formed on the peripheral portion of the first main surface 11 of the substrate 10 (in other words, the oxide coating layer 20 is formed away from the edges of the substrate 10), so the occurrence of cracks in the oxide coating layer 20 can be suppressed.

Furthermore, the planar shape of the oxide coating layer 20 is a rectangle with rounded corners, and since there are no corners where stress is concentrated, the occurrence of cracks can be suppressed.

The wiring board 100 of this embodiment can suppress the occurrence of cracks in the oxide film layer 20 during dicing, so that each piece can obtain high heat dissipation properties from the base material 10, which is mainly composed of aluminum, which has high thermal conductivity, while ensuring insulation from the oxide film layer 20. Therefore, the individual pieces can be used, for example, as wiring boards on which high-brightness LEDs, which generate a large amount of heat, are mounted in a high density. In addition, the wiring board can also be applied to semiconductors such as CPUs (Central Processing Units), power devices, and solar cells, liquid crystals, etc.

Second Embodiment
4 is an explanatory diagram showing a schematic planar configuration of a wiring board 100A of the second embodiment. The wiring board 100A of the present embodiment differs from the wiring board 100 of the first embodiment in the planar shape and arrangement of the first oxide film layer 21A, the number of oxide film layers 20, and the planar shape of the base material 10A. In the embodiments described below, the same components as those of the wiring board 100 of the first embodiment are denoted by the same reference numerals, and the preceding description is to be referred to.

As shown in the figure, the first oxide layer 21A of this embodiment has a planar shape of a rounded square, which is approximately the same as the oxide layer 20. The wiring board 100A has 14 oxide layers 20 and two first oxide layers 21. In this embodiment, 16 layers, including the 14 oxide layers 20 and the two first oxide layers 21, are arranged in 4 rows and 4 columns. In the example shown in FIG. 4, the first first oxide layer 21 is arranged in the third column of the second row, and the second first oxide layer 21 is arranged in the first column of the third row. The substrate 10A has a smaller area of the first main surface 11 than the substrate 10 of the first embodiment, and has an approximately square planar shape.

This also helps prevent cracks from occurring in the oxide layer 20 when the wiring board 100A is divided into individual pieces.

Third Embodiment
5 is an explanatory diagram that shows a schematic configuration of a wiring board 100B of the third embodiment. Fig. 5(B) shows the first main surface 11 of the base material 10, and Fig. 5(A) shows a side surface 13L on the left side of the plane of the paper in the plan view shown in Fig. 5(B), and Fig. 5(C) shows a side surface 13R on the right side of the plane of the paper. In Figs. 5(A) and (C), the oxide coating layer 20 and the wiring portion 30 are omitted. The wiring board 100B of this embodiment differs from the wiring board 100 of the first embodiment in the planar shape and arrangement of the first oxide coating layer 21B and the planar shape of the base material 10B.

The planar shape of the first oxide coating layer 21B is rectangular as shown in Figures 5(A) and (C), and the first oxide coating layer 21B is disposed on the side surface 13 of the substrate 10. The area of the first main surface 11 of the substrate 10B is smaller than that of the substrate 10 of the first embodiment, and the planar shape is approximately square.

This also helps prevent cracks from occurring in the oxide layer 20 when the wiring board 100B is divided into individual pieces.

Furthermore, according to the wiring board 100B of this embodiment, the first oxide coating layer 21B is formed on the side surface 13, which is formed on a surface different from the first main surface 11 on which the oxide coating layer 20 is formed, so that the area of the base material 10B can be made smaller than that of the base material 10 of the first embodiment. In other words, the wasted area can be made smaller.

Fourth Embodiment
Fig. 6 is an explanatory diagram illustrating a schematic configuration of a wiring board 100C according to a fourth embodiment. Fig. 6 also illustrates a cutting line L along which the wiring board 100C is divided into individual pieces. The wiring board 100C of this embodiment differs from the wiring board 100 of the first embodiment in the planar shape and arrangement of the oxide coating layer 20C and the planar shape of the base material 10C.

The planar shape of the oxide coating layer 20C in this embodiment is a square. Of the 16 oxide coating layers 20C arranged in four rows and four columns in a plan view, the four oxide coating layers 20C arranged in the first row are formed along the upper edge (side) of the substrate 10C. In other words, in a plan view, the four oxide coating layers 20C arranged in the first row have their own upper sides (sides on the upper side of the paper) aligned with the upper side (sides on the upper side of the paper) of the substrate 10C. Similarly, in a plan view, the four oxide coating layers 20C arranged in the fourth row have their own lower sides (sides on the lower side of the paper) aligned with the lower side (sides on the lower side of the paper) of the substrate 10C.

The planar shape of the substrate 10C of this embodiment is a rectangle whose short sides are shorter than those of the substrate 10 of the first embodiment. In other words, the area of the first main surface 11 of the substrate 10C is smaller than that of the substrate 10 of the first embodiment.

When the wiring board 100C is cut along the cutting line L and divided into individual pieces, two types of pieces are obtained. In one type, the first main surface 11 of the base material 10C is exposed around the entire circumference of the oxide coating layer 20C in a plan view, and in the other type, the first main surface 11 of the base material 10C is exposed only at a portion of the circumference of the oxide coating layer 20C in a plan view.

This also helps prevent cracks from occurring in the oxide layer 20C when the wiring board 100C is divided into individual pieces.

<Modifications of this embodiment>
The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit and scope of the invention. For example, the following modifications are also possible.

- The number of oxide coating layers 20 is not limited to the above embodiment and may be two or more.

- In the above embodiment, an example is shown in which multiple oxide coating layers 20 are arranged vertically and horizontally, but this is not limited thereto, and multiple oxide coating layers 20 may be arranged in a disorderly manner.

- In the above embodiment, an example is shown in which multiple oxide coating layers 20 having the same planar shape are formed, but the planar shapes of the multiple oxide coating layers may be different from each other.

- In the above embodiment, an example is shown in which the combined area of the multiple oxide coating layers 20 is larger than the combined area of the exposed portion 15, but the combined area of the multiple oxide coating layers 20 may be smaller than or equal to the combined area of the exposed portion 15.

- The main components and configuration of the wiring section 30 are not limited to those in the above embodiment. For example, it can be formed of a single layer or a laminated structure of metals such as Al, Au, Pt, Ti, Cu, Pd, Rh, Ni, W, Mo, Cr, Ag, etc., or alloys thereof. In addition, a conductive material such as ITO (Indium Tin Oxide) may be used.

- In the above embodiment, an example was shown in which the oxide coating layer 20 was not formed on the second main surface 12 of the substrate 10, but the oxide coating layer 20 may also be formed on the second main surface 12. In this way, electronic components can also be mounted on the second main surface 12 side of the substrate 10.

- In the above embodiment, an example was shown in which the first oxide film layer 21 has one power supply part 23, but the first oxide film layer 21 does not have to have a power supply part 23, or it may have two or more power supply parts 23.

- The planar shape and arrangement of the first oxide coating layer 21 are not limited to the above embodiment. The oxide coating layer 20 may be formed on the first main surface 11 of the substrate 10, and the first oxide coating layer 21 may be formed on the second main surface 12. Also, the oxide coating layer 20 may be formed on the first main surface 11 of the substrate 10, and the first oxide coating layer 21 may be formed on the second main surface 12 and the side surface 13. Furthermore, the first oxide coating layer 21 may not be formed.

- The planar shape of the oxide coating layer 20 is not limited to the above embodiment. For example, the planar shape of the oxide coating layer 20 may be a polygonal shape such as a triangle, pentagon, or hexagon, or a shape other than a polygon, such as a circle or ellipse. In the case of a polygonal shape, the corners may or may not be chamfered.

The present invention has been described above based on the embodiments and modifications, but the above-mentioned embodiments of the invention are intended to facilitate understanding of the present invention and do not limit the present invention. The present invention may be modified or improved without departing from the spirit and scope of the claims, and the present invention includes equivalents. Furthermore, if a technical feature is not described as essential in this specification, it may be deleted as appropriate.

10, 10A, 10B, 10C... Base material 11... First main surface 12... Second main surface 13, 13L, 13R... Side surface 15... Exposed part 20, 20C... Oxide film layer 21, 21A, 21B... First oxide film Layer 23... Power feeding part 30... Wiring part 100, 100A, 100B, 100C... Wiring board 110... Individual piece L... Cutting line

Claims (4)

A wiring board,
A substrate made of a metal material mainly composed of aluminum (Al),
an oxide film layer which is an anodized film of the metal material formed on the surface of the base material and has a conductive wiring portion formed on an upper surface thereof;
Equipped with
The oxide coating layers are formed to be spaced apart from each other in a plan view, and the surface of the base material is exposed between adjacent oxide coating layers;
The oxide coating layer is characterized in that, in the plan view, the oxide coating layer has a square or rectangular shape with rounded corners .
Wiring board. 2. The wiring board according to claim 1,
a total area of the oxide coating layers formed on the surface of the substrate is greater than a total area of an exposed portion of the substrate where the oxide coating layers are formed.
Wiring board. 3. The wiring board according to claim 1,
The oxide coating layer is formed in three or more layers and arranged vertically and horizontally.
Wiring board. 4. The wiring board according to claim 1,
In a plan view, the outer periphery of the oxide coating layer is such that the surface of the base material is exposed over the entire periphery.
Wiring board.

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