Wiring board

Abstract

To provide a wiring board capable of determining a direction of the wiring board with ease, and suppressing generation of defects after a semiconductor element is assembled and after an electronic component is mounted on a base substrate or the like after the semiconductor element assembly.SOLUTION: A wiring board comprises: a base substrate; and a metal fitting arranged on a first surface of the base substrate. The metal fitting has a plane-symmetrical shape with respect to a plane passing through the center of the first surface and orthogonal to the first surface. A recessed part that is at least partially recessed is formed on one outer lateral face.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a wiring board.

Background Art

[0002] A wiring board on which semiconductor elements are mounted is known (see, for example, Patent Document 1). In Patent Document 1, a vibration element as an electronic component is disposed in a cavity-shaped recess formed in a base board, and a sealed space in which the vibration element is disposed is formed by a lid body.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When processing a wiring board for mounting semiconductor elements, it is necessary to determine the direction. However, for design reasons or the like, the wiring board may have a shape that cannot determine the direction, such as a bilaterally symmetric shape. In such a case, it takes time and effort to process when mounting the semiconductor element, and there is a risk that the semiconductor element may be assembled to the wiring board in the wrong direction. In this regard, the technique described in Patent Document 1 does not consider at all how to determine the direction of the wiring board. Further, in order to determine the direction of the wiring board, a mark (a mark) may be made on the metal fitting of the wiring board using ink. However, considering the nature of the electronic component (the wiring board after assembling the semiconductor element) that is exposed to a high-temperature environment, the use of ink that gasifies at high temperature may cause problems in the electronic component, which is not preferable.

[0005] The present invention has been made to solve the above-described problems, and an object thereof is to provide a wiring board that can easily discriminate the direction of the wiring board and suppress the occurrence of defects after mounting electronic components after semiconductor element assembly and after mounting the electronic components after semiconductor element assembly on a base board or the like.

Means for Solving the Problems

[0006] The present invention has been made to solve the above-described problems and can be realized in the following forms. A wiring board comprising a base board and a fitting disposed on a first surface of the base board, the fitting having a shape that is symmetric with respect to a plane passing through the center of the first surface and perpendicular to the first surface, and having a recess formed at least partially in one outer surface, the surface roughness of the bottom surface of the recess being smaller than the surface roughness of the outer surface. A wiring board comprising a base board and a fitting disposed on a first surface of the base board, the fitting having a shape that is symmetric with respect to a plane passing through the center of the first surface and perpendicular to the first surface, and having a recess formed at least partially in one outer surface, the recess being formed at a position eccentric from the center on an axis parallel to each of the first surface and the plane in the outer surface. In addition, it can be realized in the following forms.

[0007] (1) According to one aspect of the present invention, a wiring board is provided. The wiring board includes a base board and a fitting disposed on a first surface of the base board. The fitting has a shape that is symmetric with respect to a plane passing through the center of the first surface and perpendicular to the first surface, and at least a part of one outer surface has a recessed portion that is recessed.

[0008] According to this configuration, since a recessed portion that is partially recessed is formed on the outer surface of the fitting, even if the fitting has a symmetric shape, the direction of the wiring board can be easily discriminated using the recessed portion as a mark. In this configuration, the recessed portion that functions as a mark is formed as a shape change of the outer surface of the fitting, rather than ink applied to the outer surface of the fitting. Therefore, compared with the case where a mark is formed using ink, even when the electronic component (wiring board after semiconductor element assembly) is exposed to a high-temperature environment, the recessed portion can be read normally without changing. Further, since the recessed portion does not gasify like ink, it is possible to suppress the occurrence of electrical defects and a decrease in sealing performance due to corrosion of the wiring of the base board by gas. That is, in the wiring board of this configuration, the occurrence of defects in the electronic component (wiring board after semiconductor element assembly) can be suppressed. Furthermore, since the recessed portion may be formed before the fitting is disposed on the base board, the process of applying ink after the wiring board is completed is unnecessary, and the risk of scratches and dirt occurring during ink application can be eliminated.

[0009] (2) In the wiring board of the above-described embodiment, the first surface is a rectangular surface, and the base board and the fitting have a shape that is symmetric with respect to a plane that is the plane and further parallel to one side forming the first surface, and the recess may be formed on either one of a pair of outer surfaces of the outer surface of the fitting that face each other with the plane interposed therebetween. According to this configuration, the base board and the fitting have a rectangular surface-symmetric shape. That is, even if it is difficult to distinguish the direction because both the base board and the fitting have a surface-symmetric shape, the direction of the entire wiring board can be determined by the recess functioning as a mark.

[0010] Note that the present invention can be realized in various modes, for example, in the form of a wiring board, a semiconductor device, an electronic component, and a system including these.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0012] <First Embodiment> FIG. 1 is a schematic perspective view of a wiring board 100 according to an embodiment of the present invention. The wiring board 100 of the present embodiment functions as an electronic component by mounting a semiconductor element on a base board 10. In the present embodiment, a recess 21 is formed on the outer surface of a ring fitting (fitting) 20 disposed on the base board 10, and the direction of the wiring board 100 can be determined by the recess 21 functioning as a mark.

[0013] As shown in FIG. 1, the wiring board 100 of the present embodiment includes a rectangular flat base board 10 and a ring fitting 20 disposed on the base board 10. The base board 10 includes a ceramic board 1 formed of aluminum nitride (AlN) or the like, and a metal heat sink 2 laminated on the ceramic board 1. Note that FIG. 1 shows an orthogonal coordinate system CS defined so as to be composed of an X-axis, a Y-axis, and a Z-axis that are orthogonal to each other. Each of the X-axis and the Y-axis is defined to be parallel to each side of the rectangular base board 10. The orthogonal coordinate system CS corresponds to the orthogonal coordinate system CS shown after FIG. 2.

[0014] The ring fitting 20 of the present embodiment is formed of copper (Cu), and its surface is plated with nickel (Ni) and gold (Au). The ring fitting 20 is disposed on the ceramic board 1 side of the laminated ceramic board 1 and heat sink 2 on the base board 10. The ring fitting 20 has a shape in which a rectangular cross section is formed from a rectangular parallelepiped and the central portion penetrates in the Z-axis direction. In other words, the ring fitting 20 is formed by combining two sets of flat plates parallel to the ZX plane and two sets of flat plates parallel to the YX plane to form a cavity-shaped space SP in the central portion. The Z-axis negative direction side of the ring fitting 20 is brazed to the Z-axis positive direction side surface of the ceramic board 1 of the base board 10.

[0015] The ring fitting 20 is located on the positive X-axis side and has an outer surface 20s parallel to the YZ plane. A recess 21 that is recessed toward the negative X-axis side is formed in the outer surface 20s. The recess 21 has a circular shape in the YZ plane of the outer surface 20s. The recess 21 is formed in the outer surface 20s by cutting (dent processing). A plane PL shown by a dashed line in FIG. 1 is a plane parallel to the YZ plane passing through the center of gravity of the ring fitting 20 in a state where the recess 21 is not formed. The ring fitting 20 in which the recess 21 is not formed has a shape that is symmetric with respect to the plane PL. Also, the recess 21 can be formed using press working when the ring fitting 20 is formed.

[0016] FIG. 2 is a schematic top view of the wiring board 100. FIG. 2 shows an outline of a first surface SF1 on the +Z-axis side of the base board 10 within a space SP formed by the ring fitting 20. By arranging semiconductor elements on the first surface SF1, the wiring board 100 functions as an electronic component.

[0017] As shown in FIG. 2, five rectangular through-holes HL penetrating in the thickness direction (Z-axis direction) are formed in the ceramic substrate 1 with respect to the flat plate shape. The heat sink 2 protrudes in a rectangular shape toward the +Z-axis side at positions corresponding to the five through-holes HL with respect to the flat plate shape. Note that the protruding amount of the heat sink 2 is formed such that the position of the heat sink 2 protruding toward the +Z-axis side coincides with the position of the ceramic substrate 1 toward the +Z-axis side as the base board 10.

[0018] In the present embodiment, the center of the ring fitting 20 and the center of the base board 10 are the center O. Note that the center O is a point on the first surface SF1 on a parallel Z-axis passing through the center of gravity of the ring fitting 20 and the center of gravity of the base board 10. As shown in FIG. 2, the first surface SF1 has a rectangular shape. The base board 10 and the ring fitting 20 in which the recess 21 is not formed have a plane-symmetric shape with respect to a plane PL including a central axis OL1 passing through the center O and parallel to the Y-axis and orthogonal to the first surface SF1. Therefore, it can be said that the recess 21 is formed in the outer surface 20s located on the +X-axis side among a pair of outer surfaces facing each other with the central axis OL1 serving as a plane-symmetric reference. As shown in FIG. 2, the recess 21 is formed on the +Y-axis side of the central axis OL2 in the outer surface 20s. Note that the base board 10 and the ring fitting 20 in which the recess 21 is not formed have a plane-symmetric shape with respect to a plane including a central axis OL2 passing through the center O and parallel to the X-axis and orthogonal to the first surface SF1.

[0019] FIG. 3 is an explanatory view of the concave portion 21. FIG. 3 shows a schematic cross-sectional view in which the A-A cross section in FIG. 1 is enlarged. As shown in FIG. 3, the concave portion 21 has a shape that is recessed along a central axis OL3 parallel to the X-axis with respect to the outer surface 20s. The bottom surface 21b on the negative X-axis side in the concave portion 21 is formed by dent processing. In the present embodiment, the surface roughness of the bottom surface 21b is processed to be smaller than the surface roughness of the outer surface 20s.

[0020] FIG. 4 is a flowchart of a method for manufacturing the wiring board 100 according to the present embodiment. In the manufacturing flow of the wiring board 100 shown in FIG. 4, first, the ring fitting 20 is formed into a predetermined shape (step S1). The concave portion 21 is formed by dent processing at a predetermined location of the formed ring fitting 20. The ring fitting 20 is brazed to the base board 10 in which the ceramic substrate 1 and the heat sink 2 are joined in advance (step S3). Ni plating is applied to the ring fitting 20 (step S4). Further, plating with gold (Au) is applied to the surface of the Ni plating applied to the ring fitting 20 (step S5), and the manufacturing flow of the wiring board 100 is completed. At this time, in steps S4 and S5, each metal plating may be applied to the terminals and the heat sink of the base board 10 simultaneously with the ring fitting 20. In the manufactured wiring board 100, a process of mounting a semiconductor element or the like is performed, and the mounted electronic component is used as a final product.

[0021] FIG. 5 is an explanatory view of the wiring board 100z of the comparative example. In the wiring board 100z of the comparative example, instead of the concave portion 21 in the wiring board 100 of the above embodiment, a circular ink mark MK coated with ink is formed at the position where the concave portion 21 is formed on the outer surface 20s. FIG. 5 shows the wiring board 100z of the comparative example at the same location as the wiring board 100 shown in FIG. 3. The manufacturing flow of the wiring board 100z of the comparative example does not include the process (step S2) of forming the concave portion 21 with respect to the manufacturing flow of the wiring board 100 shown in FIG. 4. Instead, the manufacturing flow of the comparative example includes a process of applying ink for forming the ink mark MK after the Au plating (step S5).

[0022] As described above, in the wiring board 100 of the present embodiment, the ring fitting 20 is brazed to the first surface SF1 of the base board 10. As shown in FIG. 2, the ring fitting 20 has a plane-symmetric shape with respect to a plane PL including a central axis OL1 that passes through the center O and is parallel to the Y axis and orthogonal to the first surface SF1. A recessed portion 21 is formed on the outer surface 20s of the ring fitting 20. Therefore, in the present embodiment, since the recessed portion 21 in which a part is recessed is formed on the outer surface 20s of the ring fitting 20, even if the ring fitting 20 has a plane-symmetric shape, the direction of the wiring board 100 can be easily determined using the recessed portion 21 as a mark. In the present embodiment, the recessed portion 21 that functions as a mark is formed as a shape change of the outer surface 20s of the ring fitting 20, rather than ink such as that applied to the outer surface 20s of the ring fitting 20 in the comparative example. Therefore, compared with the case where a mark is formed using ink as in the comparative example, even when the electronic component (the wiring board 100 after the semiconductor element is mounted) is exposed to a high-temperature environment, the recessed portion 21 can be normally read as a mark without changing. Further, since the recessed portion 21 does not gasify like ink, it is possible to suppress the occurrence of electrical defects and a decrease in sealing performance due to corrosion of the wiring of the base board 10 by gas. That is, in the wiring board 100 of the present embodiment, the occurrence of defects in the electronic component can be suppressed. Further, since the recessed portion 21 only needs to be formed before the ring fitting 20 is disposed on the base board 10, the process of applying ink after the completion of the wiring board 100 is unnecessary, and the risk of scratches and dirt occurring during the ink application can be eliminated.

[0023] Further, in the wiring board 100 of the present embodiment, as shown in FIG. 2, the first surface SF1 has a rectangular shape. The recessed portion 21 is formed on the outer surface 20s located on the positive X-axis side facing across the plane PL including the central axis OL1 that is the reference for plane symmetry. In the present embodiment, even if both the base board 10 and the ring fitting 20 have a plane-symmetric shape and it is difficult to determine the direction, the direction of the entire wiring board 100 can be determined by the recessed portion 21 functioning as a mark.

[0024] In addition, since the concave portion 21 of the present embodiment is formed by dent processing, the surface roughness of the bottom surface 21b is smaller than the surface roughness of the outer surface 20s. Therefore, in the wiring board 100 of the present embodiment, when light is incident on the outer surface 20s, the reflectance of the bottom surface 21b is different from the reflectance of the outer surface 20s, so the position of the concave portion 21 can be easily determined by the difference in appearance. For example, when the concave portion 21 is determined by image processing, the concave portion 21 on the outer surface 20s and other portions can be clearly determined by binarization. Further, when the outer surface 20s is rotated by θ (for example, 30°) around the Y axis, the concave portion 21 can be easily determined due to the difference in reflectance.

[0025] <Modification Example of the Present Embodiment> The present invention is not limited to the above-described embodiment, and can be implemented in various aspects without departing from the gist thereof. For example, the following modifications are possible.

[0026] The wiring board 100 of the above embodiment is an example, and the configuration and the like included in the wiring board 100 can be deformed within the range where the concave portion 21 is formed on the outer surface 20s of the ring fitting 20. For example, the base board 10 may be composed of only the ceramic substrate 1, or may include other configurations in addition to the ceramic substrate 1 and the heat sink 2. The base board 10 of the above embodiment is a substrate in which one ceramic substrate 1 and one heat sink 2 are laminated, but a plurality of ceramic substrates 1 may be laminated. The material of the ceramic substrate 1 may be other than AlN, and for example, oxide-based ceramics such as alumina, silica, titania, and zirconia, nitride-based ceramics such as silicon nitride and titanium nitride can be used. The materials of the heat sink 2 and the ring fitting 20 may be other than Cu, and may be Au, silver (Ag), platinum (Pt), and alloys thereof.

[0027] Regarding the position where the recess 21 is formed in the above embodiment, this is just an example, and it can be formed within the range of other outer surfaces including the outer surface 20s on the positive X-axis side. For example, the recess 21 may be formed on the outer surface parallel to the ZX plane on the negative Y-axis side of the ring fitting 20. The recess 21 may be formed at a position intersecting with the plane PL parallel to the YX plane including the central axis OL1 shown in FIG. 2, or the ZX plane passing through the central axis OL2. The recess 21 is preferably formed within the range of 90% in the central side excluding the upper 5% and the lower 5% on the base substrate 10 side in the height direction (Z-axis direction) of the outer surface. Regarding the shape of the recess 21, it may be other than circular and can be deformed within the range that functions as a mark for direction discrimination. The depth of the recess with respect to the outer surface 20s can also be deformed. Furthermore, the surface roughness of the bottom surface 21b may be larger than the surface roughness of the outer surface 20s.

[0028] In the manufacturing process of the wiring board 100 of the above embodiment, although it is stepwise from step S1 to step S2 in FIG. 4, step S1 and step S2 may be formed simultaneously using press working. Alternatively, after forming the recess 21 in step S2, Ni plating may be performed on the ring fitting 20 alone, and then step S3 may be carried out, and additionally Ni plating may be performed on the ring fitting 20 again.

[0029] As described above, the present aspect has been described based on the embodiment and the modification examples. However, the embodiments of the above-described aspects are for facilitating the understanding of the present aspect and do not limit the present aspect. The present aspect can be changed and improved without departing from its gist and the scope of the claims, and equivalents thereof are included in the present aspect. Also, if the technical features are not described as essential in this specification, they can be deleted as appropriate.

Explanation of Reference Numerals

[0030] 1...Ceramic substrate 2...Heat sink 10...Base substrate 20...Ring fitting (fitting) 20s...Outer surface 21…Concave portion 21b…Bottom surface 100…Wiring board 100z…Wiring board of the comparative example CS…Cartesian coordinate system HL…Through-hole MK…Ink mark O…Center OL1, OL2, OL3…Central axis PL…Plane SF1…First surface SP…Space

Claims

1. A wiring board, comprising a base board, and a fitting disposed on a first surface of the base board, wherein the fitting has a shape that is symmetric with respect to a plane passing through the center of the first surface and perpendicular to the first surface, and a recess that is at least partially recessed is formed on one outer surface, and a surface roughness of a bottom surface of the recess is smaller than a surface roughness of the outer surface, characterizing the wiring board.

2. The wiring board according to Claim 1, wherein the first surface is a rectangular surface, and the base board and the fitting have a shape that is symmetric with respect to a plane that is the plane and further parallel to one side forming the first surface, and the recess is formed on one of a pair of outer surfaces of the outer surface of the fitting that face each other with the plane interposed therebetween, characterizing the wiring board.

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