JP2023063761A - Thick copper embedded circuit board structure - Google Patents

Abstract

To improve heat dissipation of circuit boards.SOLUTION: One embodiment of a circuit board has a conductive base, an insulating layer disposed on the conductive base, and a thick copper circuit part embedded in the insulating layer with a portion of the thick copper circuit part exposed, and the thick copper circuit part is embedded in the insulating layer with more than 50% of its surface area covered by the insulating layer.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to circuit boards.

In the field of power electronics, electronic components for power control such as power semiconductor devices are used. Electronic components of this type are sometimes mounted on a circuit board on which an integrated circuit is formed. For example, Patent Document 1 discloses a metal plate made of aluminum, an insulating layer made of resin formed on the metal plate, a circuit pattern formed on the insulating layer, and a circuit pattern mounted on the circuit pattern. A circuit board with power semiconductor components is described.

Moreover, the cited document 2 describes that a thick conductor wiring circuit is used as a circuit pattern for mounting the electronic component in order to supply a large current to the electronic component.

Japanese Patent Application Laid-Open No. 2003-23223 JP 2008-78595 A

2. Description of the Related Art In recent years, the amount of heat generated from electronic components such as semiconductor elements has increased as the output of industrial equipment has increased. In particular, when a thick conductor wiring circuit is used as in the circuit board described in D2 to supply a large current to electronic components, a large amount of heat is generated as the electronic components operate. Substrates are required to have high heat dissipation performance.

Accordingly, an object of the present disclosure is to improve the heat dissipation performance of a circuit board.

A circuit board according to one aspect includes a conductive base, an insulating layer disposed on the conductive base, and a thick copper circuit portion embedded in the insulating layer with a portion exposed, the thick copper circuit The part is embedded in the insulating layer with 50% or more of its surface area covered with the insulating layer.

In the circuit board of the aspect described above, since 50% or more of the surface area of the thick copper circuit portion is covered with the insulating layer, the heat of the thick copper circuit portion is transferred to the insulating layer with high efficiency. The heat transferred to the insulating layer is radiated from the conductive base to the outside of the circuit board. Therefore, with this circuit board, the heat of the circuit board can be effectively radiated.

In one embodiment, the insulating layer may have a thermal conductivity of 3 W/mK or greater. When the insulating layer has a thermal conductivity of 3 W/mK or more, the heat of the thick copper circuit portion can be efficiently transferred to the insulating layer. Therefore, in this embodiment, the heat of the circuit board can be more effectively dissipated.

In one embodiment, the thickness of the thick copper circuitry may be 500 μm or greater. By setting the thickness of the thick copper circuit portion to 500 μm or more, it is possible to increase the current capacity of the circuit board and to transmit heat generated from the electronic components mounted thereon to the insulating layer with high efficiency. .

In one embodiment, the thick copper circuitry includes a buried bottom surface facing the conductive base and an exposed top surface opposite the buried bottom surface and exposed from the insulating layer, the insulating layer contacting the conductive base. Including the bottom surface and the surface layer surface opposite to the bottom surface, the distance from the surface layer surface of the insulating layer to the embedded bottom surface may be 50% or more and 130% or less of the thickness of the thick copper circuit portion. By setting the distance from the surface layer surface of the insulating layer to the buried lower surface to 50% or more and 130% or less of the thickness of the thick copper circuit portion, the contact area between the thick copper circuit portion and the insulating layer increases. The heat of the copper circuit portion is transferred to the insulating layer with high efficiency. As a result, the heat of the circuit board can be effectively radiated.

In one embodiment, the distance from the conductive base to the buried lower surface may be 50 μm or more and 300 μm or less. By setting the distance from the conductive base to the embedded lower surface to 50 μm or more and 300 μm or less, it becomes possible to electrically insulate the conductive base and the thick copper circuit portion.

In one embodiment, a thin copper circuit portion having a thickness thinner than the thick copper circuit portion may be further provided, and the thin copper circuit portion may be arranged on the surface layer of the insulating layer. In this embodiment, the thick copper circuit portion and the thin copper circuit portion can be mixed on the circuit board, and heat can be effectively dissipated from the thick copper circuit portion through which a large current flows.

In one embodiment, a thin copper circuit portion thinner than the thick copper circuit portion may be further provided, and the thin copper circuit portion may be partially exposed and embedded in the insulating layer. In this embodiment, the heat of the thin copper circuit portion can be transferred to the insulating layer with high efficiency, so the heat of the circuit board can be effectively dissipated.

In one embodiment, the insulating layer may contain a curable resin and an inorganic filler. By including a curable resin and an inorganic filler in the insulating layer, it is possible to impart high insulating properties and heat dissipation properties to the insulating layer.

In one embodiment, the content of the inorganic filler contained in the insulating layer may be 50% by volume or more. By containing 50% by volume or more of the inorganic filler, the thermal conductivity of the insulating layer can be further increased.

In one embodiment, the inorganic filler may have a thermal conductivity of 10 W/mK or higher. By setting the thermal conductivity of the inorganic filler to 10 W/m, the thermal conductivity of the insulating layer can be further increased.

The inorganic filler may have an average particle size of 1 μm or more and 100 μm or less. By setting the average particle size of the inorganic filler to 1 μm or more and 100 μm or less, the thermal conductivity of the insulating layer can be increased.

According to one aspect and various embodiments of the present invention, it is possible to improve the heat dissipation of the circuit board.

1 is a perspective view showing a circuit board according to one embodiment; FIG. FIG. 2 is a cross-sectional view of the circuit board shown in FIG. 1 taken along line II-II; FIG. 4 is a cross-sectional view showing a circuit board in which a thick-copper circuit portion and a thin-copper circuit portion are electrically connected by a wire; FIG. 4 is a cross-sectional view showing one step of a method for manufacturing a circuit board according to one embodiment; FIG. 4 is a cross-sectional view showing one step of a method for manufacturing a circuit board according to one embodiment; FIG. 4 is a cross-sectional view showing one step of a method for manufacturing a circuit board according to one embodiment; FIG. 4 is a cross-sectional view showing one step of a method for manufacturing a circuit board according to one embodiment; It is a cross-sectional view showing a circuit board according to another embodiment. It is a cross-sectional view showing a circuit board according to still another embodiment.

Embodiments of the present disclosure will be described below with reference to the drawings. In the following description, the same or corresponding elements are denoted by the same reference numerals, and redundant description will not be repeated. The dimensional proportions of the drawings do not necessarily match those of the description.

FIG. 1 is a perspective view showing a circuit board according to one embodiment. FIG. 2 is a cross-sectional view of the circuit board shown in FIG. 1 along line II-II. The circuit board 1 shown in FIGS. 1 and 2 is a metal-based circuit board on which electronic components are mounted to form an integrated circuit. It is suitably used for applications such as equipment. Examples of electronic components mounted on the circuit board 1 include power control semiconductor elements such as MOSFETs (Metal-Oxide-Semiconductor Field Effect Transistors) and IGBTs (Insulated Gate Bipolar Transistors).

As shown in FIGS. 1 and 2, the circuit board 1 includes a conductive base 10, an insulating layer 20 and a plurality of thick copper circuit portions 30. As shown in FIG. The conductive base portion 10, the insulating layer 20 and the thick copper circuit portion 30 are laminated in this order. In the following description, the lamination direction of the conductive base 10, the insulating layer 20 and the thick copper circuit portions 30 is referred to as the "thickness direction", and the arrangement direction of the plurality of thick copper circuit portions 30 is referred to as the "length direction". , the direction perpendicular to the thickness direction and the length direction may be referred to as the “width direction”.

The conductive base 10 is a conductive metal base substrate. The conductive base 10 is made of metal having higher thermal conductivity than the insulating layer 20, for example. Examples of materials for the conductive base 10 include aluminum, iron, copper, stainless steel, and alloys containing at least one of these metals. In addition, the conductive base 10 may contain a non-metallic material.

An insulating layer 20 is disposed on the conductive base 10 . The insulating layer 20 is interposed between the conductive base portion 10 and the thick copper circuit portion 30 so as to physically join the conductive base portion 10 and the thick copper circuit portion 30, and to connect the conductive base portion 10 and the thick copper circuit portion 30 together. It electrically insulates from the circuit section 30 . The insulating layer 20 also has a function of transferring heat generated by the operation of the semiconductor element mounted on the thick copper circuit portion 30 to the conductive base portion 10 . In order to realize these functions, the insulating layer 20 has high electrical insulation and thermal conductivity. For example, the insulating layer 20 may contain a curable resin and an inorganic filler and have a thermal conductivity of 3 W/mK or higher.

The curable resin contained in the insulating layer 20 is, for example, a thermosetting resin material and contains a resin and a curing agent. Examples of resins contained in the curable resin include epoxy resins, silicone resins, silicone rubbers, acrylic resins, phenolic resins, melamine resins, urea resins, unsaturated polyesters, fluorine resins, polyimides, polyamideimides, polyetherimides, poly Butylene terephthalate, polyethylene terephthalate, polyphenylene ether, polyphenylene sulfide, wholly aromatic polyester, polysulfone, liquid crystal polymer, polyether sulfone, polycarbonate, maleimide modified resin, ABS (acrylonitrile-butadiene-styrene) resin, AAS (acrylonitrile-acrylic rubber/styrene) ) resin, and AES (acrylonitrile-ethylene-propylene-diene rubber-styrene) resin.

The resin content may be 15% by volume or more, 20% by volume or more, or 30% by volume or more, and may be 70% by volume or less, 60% by volume or less, or 50% by volume, based on the total volume of the insulating layer 20. may be:

The curing agent contained in the curable resin is appropriately selected according to the type of resin. For example, when the resin is an epoxy resin, phenol novolak compounds, acid anhydrides, amino compounds, and imidazole compounds are used as curing agents. The content of the curing agent may be, for example, 0.5 parts by mass or more or 1.0 parts by mass or more, and may be 15 parts by mass or less or 10 parts by mass or less with respect to 100 parts by mass of the resin.

The inorganic filler fills the insulating layer 20 in order to increase the thermal conductivity of the insulating layer 20 . Moreover, the inorganic filler contained in the insulating layer 20 may have a thermal conductivity of, for example, 10 W/mK or more. Examples of inorganic fillers having such thermal conductivity include boron nitride, aluminum oxide, magnesium oxide, aluminum nitride, and silicon nitride. The inorganic filler may be dispersed in the insulating layer 20 in powder form. From the viewpoint of increasing the thermal conductivity of the insulating layer 20, the powdery inorganic filler may have an average particle size of, for example, 1 μm or more and 100 μm or less. In addition, the average particle size of the inorganic filler can be adjusted by adjusting the pulverization time of the massive inorganic filler.

The content of the inorganic filler contained in the insulating layer 20 is 50% by volume or more based on the total amount of the insulating layer 20 . This tends to further improve the thermal conductivity of the cured body. The content of the inorganic filler contained in the insulating layer 20 is 80% by volume or less, preferably 75% by volume or less, more preferably 70% by volume or less, based on the total amount of the insulating layer 20 . This further improves the coatability of the insulating resin composition, making it easier to obtain a cured product with excellent insulating properties.

As described above, the insulating layer 20 is formed to cover the top surface of the conductive base 10 . The insulating layer 20 includes a bottom surface 21 in contact with the top surface of the conductive base 10 and a surface layer surface 22 opposite to the bottom surface 21 . The distance between the bottom surface 21 and the surface layer surface 22, that is, the thickness T1 of the insulating layer 20 is set to, for example, 300 μm or more and 1600 μm or less.

A plurality of thick copper circuit portions 30 are arranged on the insulating layer 20 . The plurality of thick copper circuit portions 30 are arranged in the width direction of the circuit board 1 while being separated from each other. It should be noted that the circuit board 1 does not necessarily have to include a plurality of thick copper circuit portions 30 and may include at least one thick copper circuit portion 30 . The thick copper circuit portion 30 has a structure in which a desired circuit pattern is formed by processing, for example, etching. The thick copper circuit section 30 is made of copper or an alloy containing copper. The thick copper circuit section 30 is a thicker circuit conductor than general circuit conductors, and has a thickness T2 of 500 μm or more, for example. The thickness T2 of the thick copper circuit portion 30 may be, for example, 600 μm or more, 700 μm or more, 800 μm or more, or 2000 μm or less and 1000 μm or less.

Each of the plurality of thick copper circuit portions 30 is embedded in the insulating layer 20 with its part exposed. In the embodiment shown in FIG. 2, the thick copper circuit portion 30 has a generally rectangular cross-sectional shape and includes an embedded lower surface 31, an exposed upper surface 32 and four side surfaces 33. In the embodiment shown in FIG.

The embedded lower surface 31 is arranged between the bottom surface 21 and the surface layer surface 22 in the thickness direction of the circuit board 1 and is arranged to face the upper surface of the conductive base 10 . In order to ensure electrical insulation between the conductive base portion 10 and the thick copper circuit portion 30 , the embedded bottom surface 31 of the thick copper circuit portion 30 is spaced apart from the conductive base portion 10 . A distance D1 between the embedded lower surface 31 of the thick copper circuit portion 30 and the conductive base portion 10 may be set to, for example, 50 μm or more and 300 μm or less.

The exposed upper surface 32 is the surface opposite to the embedded lower surface 31 and is exposed from the insulating layer 20 . The exposed upper surface 32 provides a mounting surface on which heat generating elements such as electronic components are mounted. The exposed upper surface 32 may have a width W of 5 mm or more in the width direction of the circuit board 1 and a length of 5 mm or more in the length direction of the circuit board 1 .

The four side surfaces 33 extend in the thickness direction of the circuit board 1 and connect the embedded bottom surface 31 and the exposed top surface 32 . By embedding the thick copper circuit portion 30 in the insulating layer 20, 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more of the surface area of each side surface 33 is covered with the insulation layer 20. may The embedding depth of the thick copper circuit portion 30, that is, the distance D2 from the surface layer surface 22 of the insulating layer 20 to the embedding bottom surface 31 is 50% or more and 130% or less of the thickness T2 of the thick copper circuit portion 30. may

As described above, the thick copper circuit portion 30 is embedded in the insulating layer 20 so that the entire surface of the embedded lower surface 31 and at least a portion of the pair of side surfaces 33 of the thick copper circuit portion 30 are covered with the insulating layer 20. covered. More specifically, 50% or more of the surface area of the thick copper circuit portion 30 is covered with the insulating layer 20 . In one embodiment, 60% or more, 70% or more, 80% or more, or 90% or more of the surface area of the thick copper circuit portion 30 may be covered with the insulating layer 20 . Since the insulating layer 20 has a higher thermal conductivity than air, the heat of the thick copper circuit portion 30 is efficiently transferred to the insulating layer 20 via the embedded bottom surface 31 and the pair of side surfaces 33 . The heat transferred to the insulating layer 20 is radiated from the conductive base 10 to the outside of the circuit board 1 . That is, the circuit board 1 is formed with a heat conduction path for radiating heat generated by the electronic components to the outside of the circuit board 1 through the thick copper circuit portion 30 , the insulating layer 20 and the conductive base portion 10 .

In one embodiment, the circuit board 1 may further comprise a thin copper circuit portion 40 . In the embodiment shown in FIG. 2 , a plurality of thin copper circuit sections 40 are arranged on the surface layer surface 22 of the insulating layer 20 and arranged in the length direction of the circuit board 1 . The number of the thin copper circuit portions 40 is not limited, and the circuit board 1 may include one or more thin copper circuit portions 40 or may not include the thin copper circuit portions 40 . The thin copper circuit portion 40 is separated from the thick copper circuit portion 30 . A distance D3 between the thin copper circuit portion 40 and the thick copper circuit portion 30 may be set to, for example, 50 μm or more.

The thin copper circuit section 40 is made of, for example, copper or an alloy containing copper. The thin copper circuit portion 40 is a circuit conductor thinner than the thick copper circuit portion 30, and has a thickness T3 of, for example, 10 μm or more and less than 500 μm. The thin copper circuit section 40 has a structure in which a desired circuit pattern is formed by processing, for example, etching.

In the embodiment shown in FIG. 2, the thin copper circuit portion 40 has a generally rectangular cross-sectional shape and includes a lower surface 41, an upper surface 42 and four side surfaces 43. As shown in FIG. A lower surface 41 of the thin copper circuit portion 40 is in contact with the surface layer surface 22 of the insulating layer 20 . That is, the plurality of thin copper circuit portions 40 are arranged on the surface layer surface 22 of the insulating layer 20 . The upper surface 42 of the thin copper circuit portion 40 is located on the opposite side of the lower surface 41 and is arranged on the same plane as the exposed upper surface 32 of the thick copper circuit portion 30 . The four side surfaces 43 extend in the thickness direction of the circuit board 1 and connect the bottom surface 41 and the top surface 42 .

The upper surface 42 of the thin copper circuit portion 40 and the exposed upper surface 32 of the thick copper circuit portion 30 do not have to be arranged on the same plane. For example, the distance in the thickness direction of the circuit board 1 between the upper surface 42 of the thin copper circuit portion 40 and the exposed upper surface 32 of the thick copper circuit portion 30 may be set to be equal to or less than the thickness T3 of the thin copper circuit portion 40 . As shown in FIG. 3 , the exposed upper surface 32 of the thick copper circuit section 30 on which the electronic component 35 is mounted and the upper surface 42 of the thin copper circuit section 40 may be electrically connected by wires 45 . In this case, the length of the wire 45 can be shortened by reducing the separation distance in the thickness direction of the circuit board 1 between the upper surface 42 of the thin copper circuit portion 40 and the exposed upper surface 32 of the thick copper circuit portion 30 . It becomes possible. As a result, disconnection of the wire 45 can be prevented, and the electrical resistance of the wire 45 can be reduced.

Next, a method for manufacturing the circuit board 1 according to one embodiment will be described. In the following description, the term "resin composition" refers to a pre-cured resin material containing a curable resin and an inorganic filler, and the insulating layer 20 is formed by curing the resin composition.

In the method of manufacturing the circuit board 1 according to one embodiment, first, the conductive base 10 and the thick copper circuit portion 30 are prepared. A desired circuit pattern is formed on the thick copper circuit portion 30 by, for example, etching.

Next, as shown in FIG. 4 , a resin composition 51 in a semi-cured state (B stage) is formed on the embedded lower surface 31 of the thick copper circuit portion 30 , and the thick copper circuit portion 30 is formed through the resin composition 51 . It is crimped onto the top surface of the conductive base 10 . The semi-cured resin composition 51 is formed by, for example, applying a liquid resin composition 51 to a desired thickness on a release film, and then heating the resin composition 51 to semi-cure the resin composition 51. be done.

Next, as shown in FIG. 5, a liquid resin composition 52 is filled on the conductive base 10 so that 50% or more of the surface area of the thick copper circuit portion 30 is covered. For example, the resin composition 52 is supplied until 50% or more of the surface area of the pair of side surfaces 33 of the thick copper circuit portion 30 is immersed in the resin composition 52 . The amount of the liquid resin composition 52 supplied onto the conductive base 10 is adjusted according to the proportion of the surface area of the thick copper circuit portion 30 that is covered with the insulating layer 20 .

Next, the circuit board 1 is heated by, for example, a heating furnace until the resin composition 52 is in a semi-cured state. At this time, the circuit board 1 may be heated until the resin composition 52 is completely cured. Next, as shown in FIG. 6, a metal film 53 containing copper is laminated on the resin composition 52 . The metal film 53 laminated on the resin composition 52 may have a thickness smaller than the thickness T2 of the thick copper circuit portion 30 .

Next, the circuit board 1 on which the metal film 53 is laminated is heated using, for example, a heating furnace. As a result, the resin composition 51 and the resin composition 52 are cured to form the insulating layer 20 , and the surface layer 22 of the insulating layer 20 is pressure-bonded to the metal film 53 . After that, as shown in FIG. 7, the circuit pattern formed in the photoresist by, for example, lithography is transferred to the metal film 53 by etching to form the thin copper circuit portion 40. Next, as shown in FIG. Thus, the circuit board 1 having the conductive base portion 10, the insulating layer 20, the thick copper circuit portion 30 and the thin copper circuit portion 40 is formed.

In the circuit board 1 manufactured in this manner, 50% or more of the surface area of the thick copper circuit portion 30 is covered with the insulating layer 20 . Since the insulating layer 20 has a higher thermal conductivity than air, the heat of the thick copper circuit portion 30 is transferred to the insulating layer 20 with high efficiency through the contact portion between the insulating layer 20 and the thick copper circuit portion 30. can be transmitted. The heat transferred to the insulating layer 20 is radiated from the conductive base 10 to the outside of the circuit board 1 . Therefore, according to the circuit board 1, the heat of the thick copper circuit portion 30 can be effectively radiated.

Although circuit boards according to various embodiments have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without changing the gist of the invention.

For example, in the embodiment shown in FIG. 2, only a portion of the thick copper circuit portion 30 is embedded in the insulating layer 20 in the thickness direction of the circuit board 1, but the entire thick copper circuit portion 30 is embedded in the insulating layer 20. may be embedded in FIG. 8 is a cross-sectional view showing a circuit board 1A according to another embodiment. The thick copper circuit portion 30 of the circuit board 1A is entirely embedded in the insulating layer 20, and the exposed upper surface 32 of the thick copper circuit portion 30 is arranged on the same plane as the surface layer 22 of the insulating layer 20. The embedding depth of the thick copper circuit portion 30 is further increased so that the exposed upper surface 32 of the thick copper circuit portion 30 is arranged between the bottom surface 21 and the surface layer surface 22 in the thickness direction of the circuit board 1. good too.

The embedding depth of the thick copper circuit portion 30 can be adjusted by changing the supply amount of the resin composition 52 when forming the resin composition 52 on the conductive base portion 10 (Fig. 5 reference). For example, as shown in FIG. 8, when the exposed upper surface 32 of the thick copper circuit portion 30 and the surface layer surface 22 of the insulating layer 20 are arranged on the same plane, the exposed upper surface 32 of the thick copper circuit portion 30 is placed at the same height. The resin composition 52 is supplied up to. In addition, by attaching a release film on the exposed upper surface 32 of the thick copper circuit portion 30 and supplying the resin composition 52 to the same height as the release film, the exposed upper surface 32 of the thick copper circuit portion 30 becomes a circuit board. It can be arranged between the bottom surface 21 and the surface layer surface 22 in the thickness direction of 1 .

In the circuit board 1</b>A described above, the entire surfaces of the embedded lower surface 31 and the pair of side surfaces 33 of the thick copper circuit portion 30 are covered with the insulating layer 20 . Therefore, the heat of the thick copper circuit portion 30 can be transferred to the insulating layer 20 with higher efficiency, and the heat dissipation of the circuit board 1A can be further improved.

FIG. 9 is a cross-sectional view showing a circuit board 1B according to still another embodiment. In the circuit board 1</b>B, the thin copper circuit portion 40 is embedded in the insulating layer 20 in a partially exposed state, like the thick copper circuit portion 30 . In the circuit board 1B, the lower surface 41 of the thin copper circuit portion 40 is arranged between the bottom surface 21 and the surface layer surface 22 in the thickness direction of the circuit board 1 and arranged to face the upper surface of the conductive base 10. . A lower surface 41 of the thin copper circuit portion 40 is spaced apart from the conductive base portion 10 in order to ensure electrical insulation between the conductive base portion 10 and the thin copper circuit portion 40 . A separation distance D4 between the lower surface 41 of the thin copper circuit portion 40 and the conductive base portion 10 may be set larger than a separation distance D1 between the embedded lower surface 31 of the thick copper circuit portion 30 and the conductive base portion 10 .

In the circuit board 1B, 50% or more of the surface area of the thin copper circuit portion 40 is covered with the insulating layer 20 . In one embodiment, 60% or more, 70% or more, 80% or more, or 90% or more of the surface area of the thin copper circuit portion 40 may be covered with the insulating layer 20 . Since the surface of the thin copper circuit portion 40 is covered with the insulating layer 20, the heat of the thin copper circuit portion 40 is transmitted to the insulating layer 20 with high efficiency, and is transferred from the conductive base portion 10 to the outside of the circuit board 1. released. By embedding both the thick copper circuit portion 30 and the thin copper circuit portion 40 in the insulating layer 20 as described above, the heat of the circuit board 1B can be dissipated through the insulating layer 20 with high efficiency.

In the above-described embodiment, the thick copper circuit portion 30 and the thin copper circuit portion 40 have a substantially rectangular cross-sectional shape. but may have a partially curved shape, for example. The various embodiments described above can be combined without contradiction.

DESCRIPTION OF SYMBOLS 1, 1A, 1B... Circuit board 10... Conductive base part 20... Insulating layer 21... Bottom surface 22... Surface layer surface 30... Thick copper circuit part 31... Buried lower surface 32... Exposed upper surface 40... Thin copper circuit part.

Claims (11)

a conductive base;
an insulating layer disposed on the conductive base;
a thick copper circuit part embedded in the insulating layer in a partially exposed state,
The circuit board, wherein the thick copper circuit portion is embedded in the insulating layer with 50% or more of its surface area covered with the insulating layer. 2. The circuit board according to claim 1, wherein said insulating layer has a thermal conductivity of 3 W/mK or higher. 3. The circuit board according to claim 1, wherein said thick copper circuit portion has a thickness of 500 [mu]m or more. The thick copper circuit portion includes an embedded lower surface facing the conductive base and an exposed upper surface opposite the embedded lower surface and exposed from the insulating layer,
the insulating layer includes a bottom surface in contact with the conductive base and a surface surface opposite to the bottom surface;
4. The circuit according to any one of claims 1 to 3, wherein a distance from said surface layer surface of said insulating layer to said embedded lower surface is 50% or more and 130% or less of the thickness of said thick copper circuit portion. substrate. 5. The circuit board according to claim 4, wherein a distance from said conductive base to said embedded lower surface is 50 [mu]m or more and 300 [mu]m or less. Further comprising a thin copper circuit portion thinner than the thick copper circuit portion,
6. The circuit board according to claim 1, wherein said thin copper circuit portion is arranged on said insulating layer. 7. The circuit board according to claim 6, wherein said thin copper circuit portion is embedded in said insulating layer with a portion exposed. The circuit board according to any one of claims 1 to 7, wherein the insulating layer contains a curable resin and an inorganic filler. 9. The circuit board according to claim 8, wherein the content of said inorganic filler contained in said insulating layer is 50% by volume or more. 10. The circuit board according to claim 8, wherein the inorganic filler has a thermal conductivity of 10 W/mK or higher. The circuit board according to any one of claims 8 to 10, wherein the inorganic filler has an average particle size of 1 µm or more and 100 µm or less.

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