Wiring board, electronic device and method for manufacturing wiring board

Abstract

To provide a wiring board which is improved in heat dissipation efficiency, an electronic device and a method for manufacturing a wiring board.SOLUTION: A wiring board 100 includes: a metal plate 110; a first through-hole 113; an insulating layer 120; a second through-hole 121; a wiring layer 130; and a through-wiring 135. The first through-hole 113 is formed in the metal plate 110. The insulating layer 120 covers both surfaces of the metal plate 110 and an inner wall surface of the first through-hole 113. The second through-hole 121 is formed inside the insulating layer 120 in the first through-hole 113. The wiring layer 130 is laminated on the insulating layer 120 on both surface sides of the metal plate 110. The through-wiring 135 is formed in the second through-hole 121 and connects the wiring layers 130 on both surface sides of the metal plate 110. The metal plate 110 has a curved portion 111 which is curved in a bottomed box shape and forms a space S on one surface side of the metal plate 110.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a wiring board, an electronic device, and a method for manufacturing a wiring board. [Background technology]

[0002] In recent years, in order to realize high-density component mounting, attention has been focused on component-embedded wiring boards in which electronic components such as semiconductor chips are embedded inside the board. Such wiring boards are manufactured by forming a cavity in a board in which layers made of insulating insulating layers and conductive wiring layers are laminated, and filling the cavity in which the electronic components are placed with insulating resin that covers the electronic components. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-96292 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in wiring boards incorporating electronic components, there is a problem that it is difficult to sufficiently dissipate the heat generated by the electronic components. That is, since the periphery of the incorporated electronic components is covered with an insulating resin with low thermal conductivity, the heat generated by the electronic components is dissipated to the outside from the metal terminals with high thermal conductivity through the wiring layer of the board. However, the area occupied by the terminals in the surface area of ​​the electronic components is small, and the efficiency of heat dissipation is not very high. Therefore, it is difficult to sufficiently dissipate heat from the terminals of these electronic components, especially when the amount of heat generated by the electronic components is relatively large.

[0005] The disclosed technology has been made in view of the above, and has an object to provide a wiring board, an electronic device, and a method for manufacturing a wiring board that can improve heat dissipation efficiency. [Means for solving the problem]

[0006] In one embodiment, the wiring board disclosed in the present application has a metal plate, a first through hole, an insulating layer, a second through hole, a wiring layer, and a through wire. The first through hole is formed in the metal plate. The insulating layer covers both sides of the metal plate and the inner wall surface of the first through hole. The second through hole is formed inside the insulating layer in the first through hole. The wiring layer is laminated on the insulating layer on both sides of the metal plate. The through wire is formed in the second through hole and connects the wiring layers on both sides of the metal plate. The metal plate has a curved portion that is curved into a bottomed box shape to form a space on one side of the metal plate. Effect of the Invention

[0007] According to one aspect of the wiring board disclosed in the present application, it is possible to improve the heat dissipation efficiency. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing the configuration of a wiring board according to a first embodiment. [Diagram 2] FIG. 2 is a diagram showing the configuration of the wiring layer on the upper surface side of the metal plate. [Diagram 3] FIG. 3 is a flowchart showing the method for manufacturing the wiring board according to the first embodiment. [Figure 4] FIG. 4 is a diagram showing the structure of the metal plate. [Diagram 5] FIG. 5 is a diagram showing a specific example of the through-hole forming step. [Figure 6] FIG. 6 is a diagram showing a specific example of the insulating layer forming step. [Figure 7] FIG. 7 is a diagram showing a specific example of the through-hole forming step. [Figure 8] FIG. 8 is a diagram showing a specific example of a DFR patterning process. [Figure 9] FIG. 9 is a diagram showing a specific example of an electrolytic copper plating process. [Figure 10] FIG. 10 is a diagram showing a specific example of the DFR peeling step. [Figure 11]FIG. 11 is a diagram showing a specific example of the solder resist layer forming step. [Figure 12] FIG. 12 is a flowchart showing a method for manufacturing the electronic device according to the first embodiment. [Figure 13] FIG. 13 is a diagram showing the structure of a mounting board. [Figure 14] FIG. 14 is a diagram showing a specific example of an IC chip fixing step. [Figure 15] FIG. 15 is a diagram showing a specific example of a wiring board mounting process. [Figure 16] FIG. 16 is a diagram showing a configuration of an electronic device. [Figure 17] FIG. 17 is a diagram showing the configuration of a component mounting board. [Figure 18] FIG. 18 is a diagram showing the configuration of a wiring board according to the second embodiment. [Figure 19] FIG. 19 is a flowchart showing a method for manufacturing a wiring board according to the second embodiment. [Figure 20] FIG. 20 is a diagram showing a specific example of the solder resist layer forming step. [Figure 21] FIG. 21 is a diagram showing a specific example of the build-up process. [Figure 22] FIG. 22 is a diagram showing a specific example of the solder resist layer forming step. [Diagram 23] FIG. 23 is a top view showing the configuration of the wiring board according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of a wiring board, an electronic device, and a method for manufacturing a wiring board disclosed in the present application will be described in detail with reference to the drawings. Note that the disclosed technology is not limited to the embodiments.

[0010] (First embodiment) Fig. 1 is a diagram showing a configuration of a wiring board 100 according to a first embodiment. Fig. 1 shows a schematic cross section of the wiring board 100. The wiring board 100 shown in Fig. 1 can be used, for example, as an intermediate board that electrically connects an electronic component such as a semiconductor chip to another electronic component in an electronic device having the electronic component mounted thereon.

[0011] The wiring board 100 has a metal plate 110, an insulating layer 120, a wiring layer 130, and solder resist layers 140 and 150. In the following description, one surface of the metal plate 110 on which the solder resist layer 140 is formed is referred to as a lower surface 110a, and the other surface of the metal plate 110 on which the solder resist layer 150 is formed is referred to as an upper surface 110b. However, the wiring board 100 may be used, for example, upside down, or in any position.

[0012] The metal plate 110 is a plate-like member made of metal, and is the base material of the wiring board 100. For example, a plate-like member made of copper, aluminum, or the like can be used as the metal plate 110. The surface of the metal plate 110 may be covered with a protective film such as an oxidation prevention film. The thickness of the metal plate 110 may be, for example, about 150 to 300 μm.

[0013] Through holes 113 (an example of a first through hole) are formed in metal plate 110, penetrating metal plate 110 in the thickness direction. Through holes 113 are cylindrical through holes with an opening diameter of, for example, about 90 to 170 μm.

[0014] The insulating layer 120 is a layer that covers the lower surface 110a and the upper surface 110b of the metal plate 110 and the inner wall surface of the through hole 113. The insulating layer 120 is formed using an insulating resin such as an epoxy resin or a polyimide resin. A through hole 121 (an example of a second through hole) is formed inside the insulating layer 120 in the through hole 113, and a through wiring 135 is formed inside the through hole 121.

[0015] The wiring layer 130 is laminated on the insulating layer 120 on both sides (lower surface 110a and upper surface 110b) of the metal plate 110. The wiring layer 130 is formed using a metal such as copper or a copper alloy. The wiring layers 130 on both sides (lower surface 110a and upper surface 110b) of the metal plate 110 are connected by through-wires 135 as necessary.

[0016] The solder resist layer 140 is a layer that covers the wiring layer 130 on the lower surface 110a side of the metal plate 110 and protects the wiring. The solder resist layer 140 is a layer made of an insulating photosensitive resin such as an acrylic resin or a polyimide resin, and is one of the insulating layers. The solder resist layer 140 may be formed using an insulating non-photosensitive resin such as an epoxy resin.

[0017] The solder resist layer 140 side of the wiring board 100 is the surface to be connected to electronic components or a mounting board. At positions to be electrically connected to the electronic components or the mounting board, openings are formed in the solder resist layer 140, and the wiring layer 130 is exposed from the openings.

[0018] The solder resist layer 150 is a layer that covers the wiring layer 130 on the upper surface 110b side of the metal plate 110 and protects the wiring. The solder resist layer 150 is a layer made of an insulating photosensitive resin such as an acrylic resin or a polyimide resin, and is one of the insulating layers. The solder resist layer 150 may be formed using an insulating non-photosensitive resin such as an epoxy resin.

[0019] The solder resist layer 150 side of the wiring board 100 is a surface on which other electronic components different from the electronic components connected to the solder resist layer 140 side are mounted. At the positions where the other electronic components are mounted, openings are formed in the solder resist layer 150, and the wiring layer 130 is exposed from these openings. Also, openings are formed in the solder resist layer 150 at positions different from the positions where the other electronic components are mounted, and the wiring layer 130 is exposed from these openings.

[0020] Next, a detailed description will be given of the metal plate 110. The metal plate 110 has a curved portion 111 and a flange portion 112.

[0021] The curved portion 111 is formed by bending a metal plate-shaped member into a box shape with a bottom. The curved portion 111 forms a space S capable of accommodating electronic components on the lower surface 110a side of the metal plate 110. That is, the space S is formed in an area surrounded by the bottom and side walls of the curved portion 111.

[0022] In this embodiment, by forming the curved portion 111 in the metal plate 110, the bottom and side walls of the curved portion 111 face the top and side surfaces of the electronic components over a relatively large area via the solder resist layer 140 and the insulating layer 120. Therefore, heat generated in the electronic components accommodated in the space S is efficiently conducted to the metal plate 110 via the solder resist layer 140 and the insulating layer 120, and dissipated from the metal plate 110. As a result, the heat dissipation efficiency of the wiring board 100 can be improved.

[0023] Flange portion 112 is formed by the lower end of the outer periphery of the side wall of curved portion 111 protruding in a direction away from space S. Flange portion 112 forms a surface to be connected to the mounting board on the lower surface 110a side of metal plate 110. In other words, the lower surface of solder resist layer 140 corresponding to flange portion 112 is connected to the mounting board.

[0024] In this embodiment, by forming the flange portion 112 on the metal plate 110, the heat dissipation area of ​​the metal plate 110 is increased by the amount of the flange portion 112, and a connection surface with the mounting board can be formed on the lower surface of the solder resist layer 140. Therefore, heat conducted from the electronic components accommodated in the space S to the metal plate 110 is efficiently dissipated from the metal plate 110 to the mounting board via the insulating layer 120 and the solder resist layer 140. As a result, the heat dissipation efficiency of the wiring board 100 can be further improved.

[0025] 2 is a diagram showing a configuration of the wiring layer 130 on the upper surface 110b side of the metal plate 110. As shown in FIGS. 1 and 2, through holes 113 are formed in the curved portion 111 and the flange portion 112 of the metal plate 110. In correspondence with the position of the through hole 113 in the curved portion 111, a pad 131 (an example of a first pad) electrically connected to another electronic component is formed in the wiring layer 130 on the upper surface 110b side of the metal plate 110. In addition, in correspondence with the position of the through hole 113 in the flange portion 112, a pad 132 (an example of a second pad) used for power supply and signal transmission from a mounting board to another electronic component is formed in the wiring layer 130 on the upper surface 110b side of the metal plate 110.

[0026] The pads 131 are connected to each other by wiring 133. This makes it possible to realize signal transmission between the pads 131 in the range that overlaps with the curved portion 111 in a top view.

[0027] Meanwhile, pad 131 and pad 132 are connected by wiring 134. This makes it possible to supply power and transmit signals from the mounting board to other electronic components in the area overlapping curved portion 111 and flange portion 112 in top view.

[0028] Next, a method for manufacturing the wiring board 100 configured as above will be described by way of a specific example with reference to Fig. 3. Fig. 3 is a flowchart showing the method for manufacturing the wiring board 100 according to the first embodiment.

[0029] First, a metal plate 110 that serves as a base material for the wiring board 100 is prepared (step S101). That is, a metal plate-shaped member is subjected to, for example, press working to form the metal plate 110 having a curved portion 111 and a flange portion 112, for example, as shown in FIG. 4. FIG. 4 is a diagram showing the structure of the metal plate 110. The curved portion 111 is curved into a bottomed box shape to form a space S capable of accommodating electronic components on the lower surface 110a side of the metal plate 110. At the lower end of the outer periphery of the side wall of the curved portion 111, the flange portion 112 is formed to jut out in a direction away from the space S.

[0030] Then, through holes 113 are formed penetrating the metal plate 110 in the thickness direction (step S102). The through holes 113 are formed in both the curved portion 111 and the flange portion 112 of the metal plate 110, for example, as shown in Fig. 5, and have a cylindrical shape with an opening diameter of about 90 to 170 µm. Fig. 5 is a diagram showing a specific example of the through hole forming step. The through holes 113 are formed by, for example, punching or etching.

[0031] After the through-hole 113 is formed in the metal plate 110, an insulating layer is formed on the lower surface 110a and the upper surface 110b of the metal plate 110 (step S103). That is, an insulating layer 120 made of a heat-resistant, non-photosensitive and thermosetting resin such as epoxy resin or polyimide resin is laminated on the lower surface 110a and the upper surface 110b of the metal plate 110. A part of the insulating layer 120 laminated on the lower surface 110a and the upper surface 110b of the metal plate 110 fills the through-hole 113, for example, as shown in FIG. 6. FIG. 6 is a diagram showing a specific example of the insulating layer forming step. The insulating layers 120 on the lower surface 110a and the upper surface 110b of the metal plate 110 are integrated at the through-hole 113 to form one insulating layer 120 that covers the lower surface 110a and the upper surface 110b of the metal plate 110 and partially fills the through-hole 113.

[0032] Then, a through hole 121 is formed through the insulating layer 120 in a portion of the insulating layer 120 where the through hole 113 is filled (step S104). The through hole 121 is formed so that the insulating layer 120 remains inside the through hole 113, as shown in Fig. 7 for example. Fig. 7 is a diagram showing a specific example of the through hole forming step. The through hole 121 is formed by, for example, laser processing or drilling.

[0033] When the through holes 121 are formed in the insulating layer 120, the wiring layer 130 is formed on both sides (the lower surface 110a and the upper surface 110b) of the metal plate 110 on the insulating layer 120. Specifically, a seed layer is first formed by, for example, electroless copper plating on the surface of the insulating layer 120 including the inner wall surfaces of the through holes 121, and a dry film resist (DFR) is attached on the seed layer. Then, openings are formed at the wiring pattern formation positions of the wiring layer 130 by patterning the DFR (step S105).

[0034] That is, for example, as shown in Fig. 8, on both sides (lower surface 110a and upper surface 110b) of metal plate 110, DFR 160 is attached onto a seed layer (not shown) on the surface of insulating layer 120, and openings 161 are formed at positions for forming wiring patterns on wiring layer 130. Fig. 8 is a diagram showing a specific example of the DFR patterning step.

[0035] After the patterning of the DFR 160 is performed, electrolytic copper plating is performed (step S106) to deposit copper in the openings 161, thereby forming the wiring layer 130 having a desired wiring pattern. For example, a wiring pattern including pads 131, 132 and wiring 133 is formed on the wiring layer 130 on the upper surface 110b side of the metal plate 110.

[0036] At this time, as shown in Fig. 9, for example, the through holes 121 of the insulating layer 120 are filled with electrolytic copper plating to form through wiring 135, and the wiring layers 130 on both sides (lower surface 110a and upper surface 110b) of the metal plate 110 are electrically connected. Fig. 9 is a diagram showing a specific example of the electrolytic copper plating process.

[0037] After the wiring layer 130 is formed, the DFR 160 is peeled off (step S107), as shown in FIG. 10, and then the seed layer other than the portion where the wiring pattern is formed is removed by flash etching. FIG. 10 is a diagram showing a specific example of the DFR peeling step. For example, an alkaline stripping solution such as caustic soda or an amine is used to peel off the DFR 160. In this way, the wiring layer 130 is formed on the insulating layer 120 on both sides (the lower surface 110a and the upper surface 110b) of the metal plate 110.

[0038] After the wiring layer 130 is formed on the insulating layer 120 on both sides (the lower surface 110a and the upper surface 110b) of the metal plate 110, the wiring layer 130 is covered with the solder resist layers 140 and 150 (step S108). That is, for example, as shown in FIG. 11, the wiring layer 130 on the lower surface 110a side of the metal plate 110 is covered with the solder resist layer 140. An opening is formed in the solder resist layer 140, and the pads 136 and 137 formed on the wiring layer 130 on the lower surface 110a side of the metal plate 110 are exposed from the opening. The pad 136 can be electrically connected to an electronic component accommodated in the space S, and the pad 137 can be electrically connected to a mounting board on which the wiring board 100 is mounted. On the other hand, the wiring layer 130 on the upper surface 110b side of the metal plate 110 is covered with the solder resist layer 150. An opening is formed in the solder resist layer 150, and the pads 131, 132 formed on the wiring layer 130 on the upper surface 110b side of the metal plate 110 are exposed from this opening. The pad 131 can be electrically connected to an electronic component different from the electronic component accommodated in the space S. Fig. 11 is a diagram showing a specific example of the solder resist layer formation step. By forming the solder resist layers 140, 150, the wiring board 100 is completed.

[0039] This wiring board 100 can be used as an intermediate board for electrically connecting an electronic component such as a semiconductor chip to another electronic component in an electronic device. A method for manufacturing an electronic device having the wiring board 100 as an intermediate board will be described below with reference to Fig. 12, taking a specific example. Fig. 12 is a flow chart showing the method for manufacturing the electronic device according to the first embodiment.

[0040] First, a mounting board 210 (an example of a first wiring board) that serves as a base material of an electronic device is prepared (step S111). On the upper surface of the mounting board 210, pads 211 are formed, for example, as shown in FIG. 13. FIG. 13 is a diagram showing the structure of the mounting board 210. The pads 211 are formed of a conductor such as copper, and serve as connection terminals when the mounting board 210 is joined to the wiring board 100 (an example of a second wiring board). In addition, solder 212 for joining the mounting board 210 and the wiring board 100 is applied onto the pads 211. The application of the solder 212 is performed, for example, by printing a solder paste.

[0041] Next, an IC chip 220 (an example of an electronic component) is fixed to the upper surface of the mounting substrate 210 (step S112). That is, for example, as shown in FIG. 14, the IC chip 220 is fixed to the upper surface of the mounting substrate 210 via an adhesive layer 230. FIG. 14 is a diagram showing a specific example of the IC chip fixing step. Furthermore, solder 222 for joining the IC chip 220 and the wiring substrate 100 is applied onto the electrodes 221 of the IC chip 220. The application of the solder 222 is performed, for example, by printing a solder paste.

[0042] When the IC chip 220 is fixed on the upper surface of the mounting substrate 210, the wiring substrate 100 is mounted on the IC chip 220 and the mounting substrate 210 (step S113). That is, for example, as shown in Fig. 15, the IC chip 220 on the mounting substrate 210 is accommodated in the space S of the wiring substrate 100, and the pad 136 of the wiring substrate 100 is connected to the electrode 221 of the IC chip 220 via the solder 222. Also, the pad 137 of the wiring substrate 100 is connected to the pad 211 of the mounting substrate 210 via the solder 212. The connection by the solders 212 and 222 is performed by, for example, a reflow process. Fig. 15 is a diagram showing a specific example of the wiring substrate mounting process.

[0043] With the IC chip 220 accommodated in the space S, the top and side surfaces of the IC chip 220 face the bottom and side walls of the curved portion 111 of the metal plate 110. Therefore, heat generated in the IC chip 220 accommodated in the space S is efficiently conducted to the metal plate 110 via the solder resist layer 140 and the insulating layer 120, and dissipated from the metal plate 110. As a result, the heat dissipation efficiency of the wiring board 100 can be improved.

[0044] Furthermore, the flange 112 of the metal plate 110 can form a connection surface with the mounting board 210 on the lower surface of the solder resist layer 140. Therefore, heat conducted from the IC chip 220 accommodated in the space S to the metal plate 110 is efficiently dissipated from the metal plate 110 to the mounting board 210 via the insulating layer 120 and the solder resist layer 140. As a result, the heat dissipation efficiency of the wiring board 100 can be further improved compared to a case in which the flange 112 is not formed on the metal plate 110.

[0045] When the wiring board 100 is mounted on the IC chip 220 and the mounting board 210, a passive component such as an inductor is mounted on the wiring board 100 (step S114). That is, for example, as shown in FIG. 16, a passive component 240 (an example of another electronic component) is mounted on the upper surface of the wiring board 100. For example, an electrode 241 of the passive component 240 is connected to a pad 131 of the wiring board 100 via a solder 242. As a result, an electronic device is obtained in which the IC chip 220 and the passive component 240 are mounted and the IC chip 220 and the passive component 240 are electrically connected by the wiring board 100. FIG. 16 is a diagram showing the configuration of the electronic device. Instead of the passive component 240, an active component such as an IC chip may be mounted on the pad 131. In addition to the passive component 240, an active component such as an IC chip may be mounted on the pad 131. In addition, the passive component 240 may be, for example, a capacitor and a resistor, in addition to an inductor.

[0046] In the above first embodiment, the wiring board 100 is used as a relay board in an electronic device, but a component-mounted board on which electronic components are mounted can also be formed from the wiring board 100. Specifically, as shown in FIG. 17, an IC chip 220 is mounted on the lower surface of the wiring board 100 to obtain a component-mounted board on which the IC chip 220 is mounted. FIG. 17 is a diagram showing the configuration of a component-mounted board. For example, the IC chip 220 is accommodated in the space S of the wiring board 100, and the pad 136 of the wiring board 100 is connected to the electrode 221 of the IC chip 220 via the solder 222. That is, the component-mounted board shown in FIG. 17 is the electronic device shown in FIG. 16 with the mounting board 210 and the passive components 240 omitted.

[0047] Second embodiment In the above first embodiment, the wiring layer 130 on the upper surface 110b side of the metal plate 110 is covered with the solder resist layer 150, but an insulating layer and a wiring layer may be laminated on the wiring layer 130 on the upper surface 110b side of the metal plate 110. Therefore, in the second embodiment, a wiring board 100 in which an insulating layer and a wiring layer are laminated on the wiring layer 130 on the upper surface 110b side of the metal plate 110 will be described.

[0048] Fig. 18 is a diagram showing the configuration of a wiring board 100 according to a second embodiment. Fig. 18 shows a schematic cross section of the wiring board 100. In Fig. 18, the same parts as in Fig. 1 are denoted by the same reference numerals.

[0049] The wiring board 100 shown in FIG. 18 has an insulating layer 170 (an example of another insulating layer), a wiring layer 180 (an example of another wiring layer), and a solder resist layer 190 instead of the solder resist layer 150 shown in FIG.

[0050] The insulating layer 170 is a layer that covers the wiring layer 130 on the upper surface 110b side of the metal plate 110. Like the insulating layer 120, the insulating layer 170 is formed using an insulating resin such as an epoxy resin or a polyimide resin.

[0051] The wiring layer 180 is laminated on the insulating layer 170. The adjacent wiring layers 130 and 180 with the insulating layer 170 interposed therebetween are connected by via wiring 185 provided in the insulating layer 170 as necessary.

[0052] The solder resist layer 190 is a layer that covers the wiring layer 180 and protects the wiring. The solder resist layer 190 is a layer made of an insulating photosensitive resin such as an acrylic resin or a polyimide resin, and is one of the insulating layers. The solder resist layer 190 may be formed using an insulating non-photosensitive resin such as an epoxy resin.

[0053] The solder resist layer 190 side of the wiring board 100 is a surface on which other electronic components different from the electronic components connected to the solder resist layer 140 side are mounted. At the positions where the other electronic components are mounted, openings are formed in the solder resist layer 190, and the wiring layer 180 is exposed from these openings. Also, openings are formed in the solder resist layer 190 at positions different from the positions where the other electronic components are mounted, and the wiring layer 180 is exposed from these openings.

[0054] Next, a method for manufacturing the wiring board 100 configured as above will be described by way of a specific example with reference to Fig. 19. Fig. 19 is a flowchart showing a method for manufacturing the wiring board 100 according to the second embodiment. In Fig. 19, the same parts as in Fig. 3 are denoted by the same reference numerals.

[0055] After the wiring layer 130 is formed on the insulating layer 120 by the processes of steps S105 to S107, the wiring layer 130 on the lower surface 110a side of the metal plate 110 is covered with a solder resist layer 140 (step S201), for example, as shown in FIG. 20. FIG. 20 is a diagram showing a specific example of the solder resist layer formation step. An opening is formed in the solder resist layer 140, and the pads 136 and 137 formed on the wiring layer 130 on the lower surface 110a side of the metal plate 110 are exposed from this opening. The pad 136 can be electrically connected to an electronic component accommodated in the space S, and the pad 137 can be electrically connected to a mounting board on which the wiring board 100 is mounted.

[0056] Next, the insulating layer 170 and the wiring layer 180 are built up in this order on the wiring layer 130 on the upper surface 110b side of the metal plate 110 (step S202). Specifically, for example, as shown in FIG. 21, the insulating layer 170 is laminated on the upper surface of the wiring layer 130, and the wiring layer 180 is formed on the upper surface of the insulating layer 170. FIG. 21 is a diagram showing a specific example of the build-up process. The insulating layer 170 is formed using an insulating resin such as an epoxy resin or a polyimide resin. The wiring layer 180 is formed by plating a metal such as copper. The wiring layer 180 and the wiring layer 130 are electrically connected by a via wiring 185 provided in the insulating layer 170 as necessary. The insulating layer 170 and the wiring layer 130 may be laminated in a plurality of layers on the upper surface of the wiring layer 130.

[0057] Then, the wiring layer 180 is covered with a solder resist layer 190 (step S203), for example, as shown in FIG. 22. FIG. 22 is a diagram showing a specific example of the solder resist layer forming step. An opening is formed in the solder resist layer 190, and the pads 181, 182 formed on the wiring layer 180 are exposed from this opening. The pad 181 can be electrically connected to another electronic component different from the electronic component accommodated in the space S. By forming the solder resist layer 190, the wiring board 100 is completed.

[0058] In this embodiment, an insulating layer 170 and a wiring layer 180 are laminated on the wiring layer 130 on the upper surface 110b side of the metal plate 110, and the wiring layer 180 and the wiring layer 130 are connected by via wiring 185. This can improve the flexibility of the wiring layout of the wiring board 100.

[0059] Third embodiment Fig. 23 is a top view showing the configuration of a wiring board 100 according to a third embodiment. In Fig. 23, the same components as in Fig. 2 are denoted by the same reference numerals. In the wiring board 100 shown in Fig. 23, a flange portion 112 of a metal plate 110 is divided via a slit 112a.

[0060] In this embodiment, by providing slits 112a in flange portion 112, outside air can be introduced from slits 112a into space S in which electronic components are housed, improving the efficiency of cooling the electronic components in space S of curved portion 111. Furthermore, when wiring board 100 is connected to a mounting board, a space for arranging components on the mounting board can be secured at the position of slits 112a. This improves the flexibility of component layout on the mounting board side.

[0061] As described above, the wiring board (for example, the wiring board 100) according to the embodiment has a metal plate (for example, the metal plate 110), a first through hole (for example, the through hole 113), an insulating layer (for example, the insulating layer 120), a second through hole (for example, the through hole 121), a wiring layer (for example, the wiring layer 130), and a through wiring (for example, the through wiring 135). The first through hole is formed in the metal plate. The insulating layer covers both sides of the metal plate (for example, the lower surface 110a and the upper surface 110b) and the inner wall surface of the first through hole. The wiring layer is laminated on the insulating layer on both sides of the metal plate. The through wiring is formed in the second through hole and connects the wiring layers on both sides of the metal plate. The metal plate has a curved portion (for example, curved portion 111) that is curved into a bottomed box shape and forms a space (for example, space S) on one surface (for example, bottom surface 110a) of the metal plate, thereby improving the heat dissipation efficiency of the wiring board.

[0062] The metal plate may have a flange (for example, flange 112) formed on the outer periphery of the curved portion and protruding in a direction away from the space, thereby making it possible to further improve the heat dissipation efficiency of the wiring board.

[0063] The first through hole may be formed in the curved portion and the flange. The wiring layer on the other surface (top surface 110b, for example) of the metal plate may have a first pad (pad 131, for example), a second pad (pad 132, for example), and a wire (wire 134, for example). The first pad may be formed corresponding to the position of the first through hole in the curved portion. The second pad may be formed corresponding to the position of the first through hole in the flange. The wire may connect the first pad and the second pad. This makes it possible to supply power and transmit signals from the mounting board to other electronic components in the area that overlaps with the curved portion and the flange in a top view.

[0064] The flange may be divided via a slit (for example, slit 112a), which can improve the cooling efficiency of the electronic components in the space of the curved portion.

[0065] Moreover, the wiring board according to the embodiment may further include another insulating layer (for example, insulating layer 170) provided on the wiring layer on the other surface side of the metal plate, another wiring layer (for example, wiring layer 180) provided on the other insulating layer, and via wiring (for example, via wiring 185) provided in the other insulating layer. The other wiring layer may be connected to the wiring layer through the via wiring. This can improve the flexibility of the wiring layout of the wiring board.

[0066] The wiring board according to the embodiment may further include an electronic component (for example, an IC chip 220) that is accommodated in the space and electrically connected to the wiring layer on one side of the metal plate, thereby improving the efficiency of heat dissipation from the electronic component to the wiring board. [Explanation of symbols]

[0067] 100 Wiring board 110 Metal plate 110a Bottom side 110b Top side 111 Curved section 112 Flange 112a Slit 113 Through hole 120 Insulating layer 121 Through hole 130 wiring layer 131 Pad 132 Pad 134 Wiring 135 Through Wiring 170 Insulating layer 180 wiring layer 185 Via Wiring 210 Mounting Board 220 IC chip 240 Passive Components S space

Claims

1. A metal plate; A first through hole formed in the metal plate; an insulating layer covering both surfaces of the metal plate and an inner wall surface of the first through hole; a second through hole formed inside the insulating layer within the first through hole; wiring layers laminated on the insulating layers on both sides of the metal plate; a through-hole formed in the second through-hole and connecting the wiring layers on both surface sides of the metal plate; having The metal plate is The metal plate has a curved portion that is curved into a bottomed box shape to form a space on one side of the metal plate. A wiring board comprising:

2. The metal plate is A flange portion formed on the outer periphery of the curved portion and projecting in a direction away from the space.

2. The wiring board according to claim 1, further comprising:

3. The first through hole is The curved portion and the flange portion are formed, The wiring layer on the other surface side of the metal plate is a first pad formed in the curved portion in correspondence with a position of the first through hole; a second pad formed in the flange portion in a position corresponding to the first through hole; a wiring that connects the first pad and the second pad; 3. The wiring board according to claim 2, further comprising:

4. The flange portion is Divided through a slit 3. The wiring board according to claim 2.

5. Another insulating layer provided on the wiring layer on the other surface side of the metal plate; Another wiring layer provided on the other insulating layer; a via wiring provided in the other insulating layer; and The other wiring layer is The via wiring is connected to the wiring layer.

2. The wiring board according to claim 1.

6. An electronic component that is accommodated in the space and is electrically connected to the wiring layer on one surface side of the metal plate.

2. The wiring board according to claim 1, further comprising:

7. A first wiring board; an electronic component fixed on the first wiring board; a second wiring board mounted on the electronic component and the first wiring board; Other electronic components mounted on the second wiring board; having The second wiring board is A metal plate; A first through hole formed in the metal plate; an insulating layer covering both surfaces of the metal plate and an inner wall surface of the first through hole; a second through hole formed inside the insulating layer within the first through hole; wiring layers laminated on the insulating layers on both sides of the metal plate; a through-hole formed in the second through-hole and connecting the wiring layers on both surface sides of the metal plate; having The metal plate is a curved portion that is curved into a bottomed box shape and forms a space capable of accommodating the electronic component on one surface side of the metal plate, The electronic component includes: the wiring layer is electrically connected to the one surface of the metal plate; The other electronic components include: electrically connected to the wiring layer on the other surface side of the metal plate; 1. An electronic device comprising:

8. Providing a metal plate; forming a first through hole in the metal plate; forming an insulating layer on both sides of the metal plate, the insulating layer partially filling the first through hole; forming a second through hole in a portion of the insulating layer that fills the first through hole; forming wiring layers on the insulating layers on both surface sides of the metal plate, and forming through-holes connecting the wiring layers on both surface sides of the metal plate to the second through holes; having The step of preparing a metal plate includes: The metal plate is formed to have a curved portion that is curved into a bottomed box shape to form a space capable of accommodating electronic components on one side of the metal plate.

4. A method for manufacturing a wiring board comprising the steps of:

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