WO2021200809A1

WO2021200809A1 - Ceramic circuit board, electronic device, and metal member

Info

Publication number: WO2021200809A1
Application number: PCT/JP2021/013260
Authority: WO
Inventors: 良太青野; 穣牛島; 田中　淳一; 辰雄猿渡
Original assignee: デンカ株式会社
Priority date: 2020-03-30
Filing date: 2021-03-29
Publication date: 2021-10-07
Also published as: JPWO2021200809A1

Abstract

Provided is a ceramic circuit board (100) formed by joining a plate-shaped metal member (30) to at least one surface of a ceramic board (10) by means of a brazing material (20), wherein: the metal member (30) has a first surface (31) which faces the ceramic board (10), a second surface (32) which is the opposite surface from the first surface (31), and an edge face (33) which is present in the space between the outer peripheral edges of the first and second surfaces; the edge face (33) has a protruding portion (36) which is positioned further outward from the metal member than the boundary between the first surface (31) and the edge face (33) or the boundary (34) between the second surface (32) and the edge face; and the metal member (30) has a polygonal shape and satisfies formula (1), where θA is the angle formed between the first surface (31) and the lower end of the edge face (33) in any cross-section in the thickness direction along a diagonal of the polygon.　Formula (1): 0°<θA<90°

Description

Ceramic circuit boards, electronic devices, and metal parts

The present invention relates to ceramic circuit boards, electronic devices, and metal members.

Ceramic circuit boards in which a metal member is bonded to a ceramic substrate are widely used for electronic parts, mechanical parts, and the like. For example, in power devices such as those for electric railways, vehicles, and industrial machines that require high-voltage and large-current operations, electronic devices in which semiconductor elements are mounted on a ceramic circuit substrate are used.
As one of the methods for joining the ceramic substrate and the metal member, there is a method of joining the ceramic substrate and the metal member using a brazing material. In this case, in general, a brazing material containing silver / copper and an active metal is applied to a ceramic substrate, a metal member is placed on the brazing material, and heat treatment is performed at an appropriate temperature to form a ceramic substrate and a metal plate. To join.

For example, in Patent Document 1, in a ceramic circuit substrate in which a metal plate is integrally bonded to the surface of a ceramic substrate via a brazing material layer, the area of the bonding surface between the metal plate and the brazing material layer is the non-bonding surface of the metal plate. A ceramic circuit substrate is disclosed, which is smaller than the surface area on the side and the area of the joint surface between the brazing material layer and the ceramics substrate is larger than the area of the joint surface between the metal plate and the brazing material layer.

Japanese Unexamined Patent Publication No. 2001-332854

As a result of examination by the inventors, in the ceramic circuit board having the shape disclosed in Patent Document 1, the brazing material rises to the surface of the metal member in the step of joining the metal member to the ceramic substrate, and the brazing material gets wet with solder. It has become clear that the sex may be reduced.

According to the present invention, in a ceramic circuit board formed by joining a plate-shaped metal member to at least one surface of a ceramic substrate via a brazing material.
The metal member has a first surface facing the ceramic substrate, a second surface opposite to the first surface, and end faces existing between the outer peripheral ends of both sides thereof.
The end face has a convex portion located outside the metal member from the boundary between the end face and the first surface or the boundary between the end face and the second surface.
The metal member is polygonal and at any of the cut surfaces in the thickness direction along its diagonal.
When the angle formed by the lower end of the end surface and the first surface is θ _A , a ceramic circuit board satisfying the following equation (1) is provided.
Equation (1) 0 ° <θ _A <90 °

Further, according to the present invention, it is a plate-shaped metal member bonded to one surface of a ceramic substrate with a brazing material.
The metal member has a first surface facing the ceramic substrate, a second surface opposite to the first surface, and end faces existing between the outer peripheral ends of both sides thereof.
The end face has a recess located inside the metal member with respect to the boundary between the end face and the second face.
As the end face, a ceramic circuit board having a convex portion located outside the boundary between the end face and the first surface or the boundary between the end face and the second surface is provided. ..

Further, according to the present invention, an electronic device including the ceramic circuit board is provided.

In a ceramic circuit board in which a plate-shaped metal member is bonded to at least one surface of a ceramic substrate via a brazing material.
The metal member has a first surface facing the ceramic substrate, a second surface opposite to the first surface, and end faces existing between the outer peripheral ends of both sides thereof.
The end face has a convex portion located outside the metal member from the boundary between the end face and the first surface or the boundary between the end face and the second surface.
The metal member is polygonal and at any of the cut surfaces in the thickness direction along its diagonal.
When the angle formed by the lower end of the end surface and the first surface is θ _A ,
A metal member satisfying the following formula (1) is provided.
Equation (1) 0 ° <θ _A <90 °

According to the present invention, a ceramic circuit board that prevents the brazing material from rising to the surface of the metal member when joining a plate-shaped metal member to the ceramic substrate via a brazing material, and an electronic device including the ceramics circuit board. Also, it is possible to provide a metal member to be bonded to a ceramic substrate.

It is sectional drawing which shows typically the structure of the ceramics circuit board which concerns on embodiment. It is a top view which shows typically the structure of the ceramics circuit board which concerns on embodiment. It is sectional drawing which shows typically the structure of the metal member in the ceramics circuit board which concerns on 1st Embodiment. It is sectional drawing which shows typically the structure of the ceramic circuit board which concerns on 2nd Embodiment. It is sectional drawing which shows typically the structure of the ceramic circuit board which concerns on 3rd Embodiment. It is a figure which shows the example of the cross-sectional photograph of the metal member which concerns on 3rd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all drawings, similar components are designated by the same reference numerals, and description thereof will be omitted as appropriate. Moreover, the figure is a schematic view and does not match the actual dimensional ratio.

<Ceramics circuit board>
First, the outline of the ceramic circuit board according to the present embodiment will be described with reference to FIGS. 1 and 2.
FIG. 1 is a cross-sectional view schematically showing the overall configuration of the ceramic circuit board 100 according to the present embodiment. The ceramic circuit board 100 according to the present embodiment includes a ceramic substrate 10, a brazing material 20, and a plate-shaped metal member 30. A plate-shaped metal member 30 is bonded to at least one surface of the ceramic substrate 10 via a brazing material 20, and the ceramic substrate 10, the brazing material 20, and the metal member 30 are fixed to each other by joining.

The ceramic substrate 10 has a first surface 11 and a second surface 12. A plate-shaped metal member 30 is joined to the ceramic substrate 10 on the second surface 12 via a brazing material 20. The structure of the ceramic circuit board 100 according to the present embodiment is not limited to the above structure. For example, the ceramic circuit board 100 has a first surface 11 or a second surface 12 as shown in FIG. 1 (a). A plate-shaped metal member 30 may be joined to either of them, or as shown in FIG. 1 (b), the metal member 30 is joined to both sides of the first surface 11 and the second surface 12. You may. Further, FIG. 2 shows a top view schematically showing the ceramic circuit board 100 according to the present embodiment. In the ceramic circuit board 100, one metal member 30 may be bonded to the first surface 11 and the second surface 12, respectively, or one metal member 30 may be bonded to the first surface 11 and the second surface 11 is bonded to the second surface 11. Two or more metal members 30 may be joined to the surface 12, or two or more metal members 30 are joined to the first surface 11, and one metal member 30 is joined to the second surface 12. Alternatively, two or more metal members 30 may be joined to the first surface 11 and the second surface 12, respectively. The metal member 30 is polygonal in a plan view, and is preferably rectangular.

Hereinafter, each configuration of the ceramic circuit board according to this embodiment will be described in detail.

<Metal member>
(First Embodiment)
The first embodiment will be described in detail with reference to FIG. FIG. 3 is a cross-sectional view schematically showing the configuration of the ceramic circuit board 100 of the first embodiment.

In the first embodiment, the metal member 30 exists between the first surface 31 facing the ceramic substrate, the second surface 32 opposite to the first surface 31, and the outer peripheral ends of both sides thereof. It has an end face 33 to be formed. The end face 33 has a convex portion 36 that is convex outward of the metal member 30. Further, the convex portion 36 is located outside the metal member 30 than either the boundary 34 between the end surface 33 and the first surface 31 or the boundary 35 between the end surface 33 and the second surface 32. It is preferable that the convex portion 36 is provided so as to orbit the entire circumference of the end surface 33. For example, in FIG. 2B, two rectangular metal members 30 are provided in a top view, but a convex portion 36 is provided so as to orbit all four sides of the rectangle of the end face 33 of each metal member 30. May be done.

In the first embodiment, the metal member 30 has an angle formed by the lower end of the end surface 33 and the first surface 31 at any of the cut surfaces in the thickness direction along the diagonal line, as shown here in the region α. Is θ _A , the following equation (1) is satisfied.
Equation (1) 0 ° <θ _A <90 °
The lower limit of θ _A is preferably 35 ° or more, and particularly preferably 40 ° or more. The upper limit of θ _A is preferably 87 ° or less, particularly preferably 82 ° or less.
Here, any of the cut surfaces of the metal member 30 in the thickness direction along the diagonal line refers to, for example, a cross section when cut along the straight lines a to d in FIG. When the metal member 30 is rectangular, it is preferable that the two diagonal cut surfaces satisfy the _{above range of θ A.}

Hereinafter, with reference to FIG. 3 will be described in detail a method for measuring theta _A. The angle formed by the straight line connecting the lower end (boundary 34) of one end face 33 and the lower end (not shown) of the other end face (not shown) and the inclination A at the lower end (boundary 34) of the end face 33. Let θ _A. The above θ _A can generally be approximated to the angle formed by the first surface 31 and the inclination A at the lower end (boundary 34) of the end surface 33.

The ceramic circuit board according to the first embodiment is a ceramic circuit board capable of more reliably suppressing the rising of the brazing material by forming the end face 33 of the metal member 30 into the above shape. That is, conventionally, in the brazing step of joining the ceramic substrate 10 and the metal member 30 via the brazing material 20, the brazing material 20 travels along the end surface 33 of the metal member 30 at the joint end portion and is the upper surface of the metal member 30. It may rise to the (second surface 32), and when a semiconductor chip or the like is mounted on the upper surface (second surface 32) of the metal member 30 in a subsequent process, the solder wettability is reduced by the raised brazing material. As a result, poor soldering and poor appearance occurred, which contributed to the decrease in yield.

According to the first embodiment, the end surface 33 of the metal member 30 is more than the boundary 34 between the end surface 33 and the first surface 31 or the boundary 35 between the end surface 33 and the second surface 32. By forming the shape having the convex portion 36 located on the outside of the metal member 30 and making the angle formed by the lower end of the end surface 33 and the first surface 31 an acute angle, the brazing material is the second metal member 30. Since the path to reach the surface 32 of the surface 32 has a plurality of inversions, becomes more complicated, and becomes longer, it is possible to reliably suppress the rise of the brazing material.

Further, in order to suppress the rising of the brazing material, for example, when a convex portion is provided at the end of the metal member, the amount of protrusion of the convex portion must be increased, and the metal member having the convex portion at the end must be used. , There is a risk that a discharge will occur between the metal member having a convex portion at another adjacent end and the withstand voltage will decrease.
_{According to the first embodiment, by setting the angle θ A} formed by the lower end of the end surface 33 and the first surface 31 to be an acute angle, it is possible to surely suppress the rising of the brazing material and to make it convex. Since the amount of protrusion of the portion 36 can be suppressed, the risk of discharge can be reduced, and restrictions on circuit design such as the distance between patterns must be set to a certain level or more in consideration of the amount of protrusion can be relaxed. Can be done.

In the first embodiment, the convex portion 36 is outside the metal member 30 of either the boundary 34 between the end surface 33 and the first surface 31 or the boundary 35 between the end surface 33 and the second surface 32. It is preferably located at.
With the above shape, the path for the brazing material to reach the second surface 32 of the metal member 30 has three or more inversions, is more complicated, and becomes longer, so that the brazing material is more reliable. It is possible to suppress the rise of metal.

Further, in the first embodiment, the metal member 30 preferably satisfies the following formula (2) when the angle formed by the upper end of the end surface 33 and the second surface 32 is θ _B.
Equation (2) 0 ° <θ _B <90 °
The lower limit of θ _B is preferably 40 ° or more, and particularly preferably 45 ° or more. The upper limit of θ _B is preferably 88 ° or less, and particularly preferably 83 ° or less.
By _{setting θ B} to an acute angle, the brazing material is inverted again in the latter half of the path until it reaches the second surface 32 of the metal member 30, and the brazing material can be more reliably suppressed from rising. can.

The _{method for measuring θ B is the same as} _{the method for measuring θ A} described above, and will be described with reference to FIG. As shown in the region β, at the straight line connecting the upper end (boundary 35) of one end face 33 and the upper end (not shown) of the other end face (not shown) and at the upper end (boundary 35) of the end face 33. _{Let θ B} be the angle formed by the inclination B. The above θ _B can generally be approximated to the angle formed by the second surface 32 and the inclination B at the upper end (boundary 35) of the end surface 33.

By appropriately setting the horizontal distance between the boundary 34 between the end surface 33 and the first surface 31 and the apex of the convex portion 36, the risk of withstand voltage reduction can be suppressed and the brazing material can be reliably inserted. The rise can be suppressed.

In addition to the shape of the metal member 30, the amount of the brazing material applied also affects the liftability of the brazing material. The coating amount of the brazing material is the dry film thickness of the brazing material paste before the joining step, and can be, for example, 2 μm or more and 40 μm or less.

(Second embodiment)
Hereinafter, the second embodiment will be described in detail with reference to FIG. FIG. 4 is a cross-sectional view schematically showing the configuration of the ceramic circuit board 101 of the second embodiment.
In the second embodiment, the metal member 30 exists between the first surface 31 facing the ceramic substrate, the second surface 32 opposite to the first surface 31, and the outer peripheral ends of both sides thereof. It has an end face 33. The end surface 33 has a recess 37 located inside the metal member 30 with respect to the boundary 35 between the end surface 33 and the second surface 32, and the end surface 33 is the boundary 34 between the end surface 33 and the first surface 31. Alternatively, it has a convex portion 36 located outside the metal member 30 with respect to the boundary 35 between the end surface 33 and the second surface 32.

In the second embodiment, the metal member 30 has a recess 37 located inside the metal member 30 with respect to the boundary 35 between the end surface 33 and the second surface 32, and the end surface 33 and the first surface 32. By having the boundary 34 with the surface 31 or the convex portion 36 located outside the metal member 30 with respect to the boundary 35 between the end surface 33 and the second surface 32, the brazing material is the third of the metal member 30. Since the path to reach the second surface 32 has a plurality of inversions, becomes more complicated, and becomes longer, it is possible to more reliably suppress the rise of the brazing material. Further, according to the ceramic circuit board according to the present embodiment, the end face 33 has the concave portion 37 and the convex portion 36, so that the protrusion amount of the convex portion 36 can be suppressed and the brazing material can be reliably lifted. Since it can be suppressed, it is possible to suppress the decrease in the withstand voltage and surely suppress the rise of the brazing material.

In the second embodiment, in the metal member 30, the end surface 33 is located on the first curved surface 38, which is concave inside the metal member 30, and on the second surface 32 side of the first curved surface 38, and the metal member 30. It is preferable to have a concave second curved surface 39 and a ridge line 40 sandwiched between the first curved surface 38 and the second curved surface 39 on the inner side. In the metal member 30 according to the second embodiment, since the end surface 33 has two recesses 37 and a ridge line 40, the route for the brazing material to reach the second surface 32 of the metal member 30 is three times. Since it has the above inversion, is more complicated, and becomes longer, it is possible to more reliably suppress the rising of the brazing material.

In the second embodiment, in the metal member 30, the convex portion 36 is more than one of the boundary 34 between the end surface 33 and the first surface 31 and the boundary 35 between the end surface 33 and the second surface 32. It is preferably located on the outside of the metal member 30.
Further, in the second embodiment, it is preferable that the ridge line 40 of the metal member 30 is located at the outer edge of the metal member rather than the outer peripheral ends of the first surface 31 and the second surface 32.
With the above shape, the path for the brazing material to reach the second surface 32 of the metal member 30 is more complicated and longer, so that the brazing material can be more reliably suppressed from rising. ..

In addition to the shape of the metal member 30, the liftability of the brazing material is also affected by the amount of the brazing material applied, the pressure applied to the laminate of the ceramic substrate 10 and the metal member 30 at the time of joining, and the like. When the amount of the material applied is large, or when the pressure applied to the laminate is large, the horizontal distance between the boundary 34 between the end surface 33 and the first surface 31 and the apex of the convex portion 36 is increased, and so on. It is preferable to adjust the shape of the metal member 30 in consideration of the balance between the factors that promote the rise and the factors that suppress the rise.

(Third embodiment)
Hereinafter, the third embodiment will be described in detail with reference to FIGS. 5 and 6. FIG. 5 is a cross-sectional view schematically showing the configuration of the ceramic circuit board 102 of the third embodiment. FIG. 6 shows an example of a cross-sectional photograph when a copper plate is used as the metal member 30 of the third embodiment. Hereinafter, the shape of the end face 33 of the metal member 30, which is different from the first and second embodiments, will be described.

In the metal member 30 of the third embodiment, the end surface 33 is located on the first curved surface 38 recessed inside the metal member 30 and on the second surface 32 side of the first curved surface 38, and is inside the metal member 30. It has a concave second curved surface 39, and a convex portion 36 having a curved convex shape 45 on the outer side sandwiched between the first curved surface 38 and the second curved surface 39.

The first curved surface 38 and the convex portion 36 are continuous at the inflection point 43. The second curved surface 39 and the convex portion 36 are continuous at the inflection point 44.

In such a configuration, the metal member 30 according to the third embodiment has a metal brazing material because the end face 33 has two concave portions 37 (first curved surface 38 and second curved surface 39) and a convex portion 36. Since the path to reach the second surface 32 of the member 30 has three or more inversions, is more complicated, and becomes longer, it is possible to more reliably suppress the rise of the brazing material.

As a method for producing the metal member 30 having a specific end shape according to the first to third embodiments as described above, a plate-shaped metal material having a predetermined masking is individually separated by etching. The method for etching is as shown below.
First, the surface of the metal material is masked by a known method. Here, in masking, it is preferable that the same pattern is applied to both sides of the metal material by aligning both sides by a known method.
Next, the masked metal material is separated by etching. A known etching solution can be used as the etching solution. For example, when the metal material is a copper plate, specific examples thereof include ferric chloride, cupric chloride, sulfuric acid, and hydrogen peroxide solution. By etching a plate-shaped metal material having the same masking on both sides, the masking patterns are etched from both sides, and the metal member 30 having a specific end shape according to the present embodiment can be obtained.
The shape of the metal member 30 can be adjusted by etching conditions and the like. For example, by adjusting the concentration of the etching solution and the etching time, it is possible to adjust the amount of protrusion _{of θ A} , θ _{B, and the convex portion 36 of the metal member 30.}
Subsequently, by removing the masking, the metal member 30 is obtained.

Examples of the metal used for the metal member 30 according to the present embodiment include copper, aluminum, iron, nickel, chromium, silver, molybdenum, cobalt alone or an alloy thereof. As will be described later, copper is preferable from the viewpoint of joining the metal member 30 to the ceramic substrate 10 with a brazing material containing an active metal, and from the viewpoint of conductivity and heat dissipation.

When using a copper plate, its purity is preferably 90% or more. By setting the purity to 90% or more, a ceramic circuit board having sufficient conductivity and heat dissipation can be obtained, and when the ceramic substrate and the copper plate are joined, the reaction between the copper plate and the brazing material proceeds sufficiently, and the reliability is high. A ceramic circuit board can be obtained.

The thickness of the metal member 30 according to the present embodiment is not particularly limited, but is generally 0.1 mm or more and 1.5 mm or less. The thickness of the metal member 30 is particularly preferably 0.2 mm or more from the viewpoint of heat dissipation, and preferably 0.5 mm or less from the viewpoint of heat resistance cycle characteristics.

<Ceramics substrate>
The ceramic substrate 10 used in the ceramic circuit substrate according to the present embodiment is not particularly limited, and is not particularly limited. Examples thereof include carbide-based ceramics such as silicon carbide and boron-based ceramics such as lanthanum boring. As will be described later, non-oxide ceramics such as aluminum nitride and silicon nitride are preferable from the viewpoint of joining the metal member 30 to the ceramic substrate 10 with a silver-copper brazing material containing an active metal. From the viewpoint of excellent thermal conductivity, an aluminum nitride substrate is preferable.

The thickness of the ceramic substrate 10 according to the present embodiment is not particularly limited, but is preferably 0.2 mm or more and 1.5 mm or less. By setting the value within the above numerical range, sufficient strength and durability can be maintained and thermal resistance can be suppressed.

<Blazed material>
In the ceramics circuit substrate according to the present embodiment, the brazing material 20 is a silver-copper system containing at least one active metal selected from titanium, zirconium, hafnium, niobium, tantalum, vanadium, aluminum, and tin in the brazing material. It is preferably composed of brazing material. The Ag / Cu ratio in the brazing filler metal is increased from 72% by mass: 28% by mass, which is the eutectic composition of Ag and Cu, to prevent coarsening of the Cu-rich phase and to be Ag-rich. It is possible to form a brazing layer structure in which the phases are continuous.
Further, if the amount of Ag powder compounded is large and the amount of Cu powder compounded is small, the Ag powder may not be completely dissolved at the time of bonding and may remain as a bonding void. Therefore, the blending ratio of Ag powder and Cu powder, Sn powder or In powder is Ag powder: 85.0 parts by mass or more and 95.0 parts by mass or less, Cu powder: 5.0 parts by mass or more and 13.0 parts by mass or less. , Sn powder or In powder: preferably composed of 0.4 parts by mass or more and 3.5 parts by mass or less. By keeping the value within the above numerical range, it is possible to prevent the melting temperature of the brazing material from rising excessively, to enable joining at an appropriate temperature, and to reduce the thermal stress caused by the difference in the coefficient of thermal expansion during joining. It is possible to improve the heat resistance cycle property.

The amount of the active metal such as titanium added is preferably 1.5 parts by mass or more and 5.0 parts by mass or less with respect to 100 parts by mass in total of Ag powder, Cu powder, Sn powder or In powder. By appropriately adjusting the amount of the active metal added, the wettability to the ceramic plate can be further enhanced, and the occurrence of bonding defects can be further suppressed. In addition, the residual unreacted active metal can be suppressed, and discontinuity of the Ag-rich phase can be suppressed.

<Manufacturing method of ceramic circuit board>
The method for manufacturing the ceramic circuit board according to the present embodiment will be described below.
First, the ceramic substrate 10 and the metal member 30 are prepared. The aspects of the ceramic substrate 10 and the metal member 30 are as described above.
Next, a brazing paste is prepared. The composition of the metal component of the brazing filler metal is as described above. Ag powder: 85.0 parts by mass or more and 95.0 parts by mass or less, Cu powder: 5.0 parts by mass or more and 13.0 parts by mass or less, Sn powder or In Powder: A powder consisting of 0.4 parts by mass or more and 3.5 parts by mass or less is preferable. The amount of the active metal such as titanium added is preferably 1.5 parts by mass or more and 5.0 parts by mass or less with respect to 100 parts by mass in total of Ag powder, Cu powder, Sn powder or In powder.
A brazing paste can be obtained by mixing these metal powders with a resin, a solvent, and if necessary, a dispersant or the like by a known method.
Subsequently, the brazing material paste is applied to one side or both sides of the ceramic substrate 10. The coating method is not particularly limited, and coating can be performed by, for example, screen printing. The dry film thickness of the applied brazing paste is preferably, for example, 1 μm or more and 50 μm or less.

Next, the metal member 30 is stacked so as to be in contact with the brazing paste applied to the ceramic substrate 10 and heated in a heating furnace to join the ceramic substrate 10 and the metal member 30.
In the present embodiment, the joining temperature for joining the ceramic substrate 10 and the metal member 30 is preferably 780 ° C. or higher and 850 ° C. or lower, and more preferably lower than 800 ° C. The degree of vacuum at the time of joining ^{is preferably 1 × 10 -3} Pa or less. Further, it is desirable that the holding time at the joining temperature is 10 minutes or more and 60 minutes or less.
By setting the joining temperature, the degree of vacuum, and the joining time within the above ranges, a compound containing an active metal is sufficiently generated, and the ceramic substrate 10 and the metal member 30 can be joined over the entire surface. In addition, if the bonding temperature is high or the holding time is too long, the thickness unevenness of the brazing material layer after bonding may increase, and cracks may occur due to ultrasonic bonding. By setting the degree of vacuum and the bonding time within the above ranges, it is possible to reduce uneven thickness of the brazing material after bonding.
As described above, the ceramic circuit board according to the present embodiment can be obtained.

The ceramic circuit board according to this embodiment can be used for an electronic device, and can also undergo a circuit pattern forming step by etching. When forming a circuit pattern on the ceramic circuit board according to the present embodiment, the metal member 30 can be etched by applying an etching resist. There are no particular restrictions on the etching resist, and known ultraviolet curable types and thermosetting types can be used. Further, the method for applying the etching resist is not particularly limited, and a known application method such as a screen printing method can be adopted.
The etching solution is not particularly limited, and a known etching solution can be used. When the metal member 30 is a copper plate, a ferric chloride solution, a cupric chloride solution, sulfuric acid, a hydrogen peroxide solution, or the like is used. A ferric chloride solution or a cupric chloride solution is preferable.

A brazing material, its alloy layer, a nitride layer, etc. may remain on the ceramic circuit board from which unnecessary metal parts have been removed by etching. In that case, an aqueous solution of ammonium halide, an inorganic acid such as sulfuric acid or nitric acid, It is common to remove them with a solution containing aqueous hydrogen peroxide. After forming the circuit, the etching resist can be peeled off by a known method. The peeling method is not particularly limited, and examples thereof include a method of immersing in an alkaline aqueous solution.

The

ceramic circuit boards

100, 101, and 102 according to the present embodiment can be made into an electronic device, for example, by mounting a semiconductor chip or the like on the second surface 32 of the metal member 30.
The

ceramic circuit boards

100, 101 and 102 according to the present embodiment can be particularly preferably applied to power devices that require high voltage and large current operation, such as those for electric railways, vehicles, and industrial machines.
The present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the range in which the object of the present invention can be achieved are included in the present invention.

Hereinafter, examples of the embodiments of the present invention will be added together. These forms are included in the present invention.
1. 1. In a ceramic circuit board in which a plate-shaped metal member is bonded to at least one surface of a ceramic substrate via a brazing material.
The metal member has a first surface facing the ceramic substrate, a second surface opposite to the first surface, and end faces existing between the outer peripheral ends of both sides thereof.
The end face has a convex portion located outside the metal member from the boundary between the end face and the first surface or the boundary between the end face and the second surface.
The metal member is polygonal and at any of the cut surfaces in the thickness direction along its diagonal.
When the angle formed by the lower end of the end surface and the first surface is θ _A ,
A ceramic circuit board that satisfies the following formula (1).
Equation (1) 0 ° <θ _A <90 °
2. 1. The metal member is rectangular. The ceramic circuit board described in.
3. 3. When the angle formed by the upper end of the end face and the second face is θ _B ,
1. Satisfy the following equation (2). Or 2. The ceramic circuit board described in.
Equation (2) 0 ° <θ _B <90 °
4. The convex portion is provided so as to orbit the entire circumference of the end face. Or 2. The ceramic circuit board described in.
5. In a ceramic circuit board in which a plate-shaped metal member is bonded to at least one surface of a ceramic substrate via a brazing material.
The metal member has a first surface facing the ceramic substrate, a second surface opposite to the first surface, and end faces existing between the outer peripheral ends of both sides thereof.
The end face has a recess located inside the metal member with respect to the boundary between the end face and the second face.
The end face is a ceramic circuit board having a convex portion located outside the metal member from the boundary between the end face and the first surface or the boundary between the end face and the second surface.
6. The end face
First curved surface concave inside the metal member,
The second curved surface, which is located on the second surface side of the first curved surface and is concave inside the metal member, and
It has a ridgeline sandwiched between the first curved surface and the second curved surface. The ceramic circuit board described in.
7. The end face has a convex portion located outside the metal member from the boundary between the end face and the first surface and the boundary between the end face and the second surface. ~ 6. The ceramic circuit board according to any one of the above.
8. 6. The ridgeline is located at the outer edge of the metal member rather than the outer peripheral ends of the first surface and the second surface. The ceramic circuit board described in.
9. 1. The metal member is a copper plate. ~ 8. The ceramic circuit board according to any one of the above.
10. 1. The brazing material comprises at least one metal selected from titanium, zirconium, hafnium, niobium, tantalum, vanadium, aluminum, and tin. ~ 9. The ceramic circuit board according to any one of the above.
11. 1. The ceramic substrate is at least one selected from silicon nitride and aluminum nitride. ~ 10. The ceramic circuit board according to any one of the above.
12. 1. 1. ~ 11. The ceramic circuit board according to any one of the above, wherein a plate-shaped metal member is bonded to both sides of the ceramic substrate via a brazing material.
13. 1. 1. ~ 12. An electronic device including the ceramic circuit board according to any one of the above.
14. 13. An electronic device according to the above, which is a power device.
15. A plate-shaped metal member that is joined to one surface of a ceramic substrate with a brazing material.
The metal member has a first surface facing the ceramic substrate, a second surface opposite to the first surface, and end faces existing between the outer peripheral ends of both sides thereof.
The end face has a convex portion located outside the metal member from the boundary between the end face and the first surface or the boundary between the end face and the second surface.
The metal member is polygonal and at any of the cut surfaces in the thickness direction along its diagonal.
When the angle formed by the lower end of the end surface and the first surface is θ _A ,
A metal member satisfying the following formula (1).
Equation (1) 0 ° <θ _A <90 °
16. The convex portion is provided so as to orbit the entire circumference of the end face. The metal member described in.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the description of these Examples. Table 1 shows the evaluation results of Examples 1 to 3 and Comparative Examples 1 and 2. In the evaluation in the table, "◎" indicates "no rise", "○" indicates "slight rise", and "x" indicates "clear rise". Further, the presence / absence of the item "convex portion" in the table is more metal than the boundary 34 between the end surface 33 and the first surface 31 or the boundary 35 between the end surface 33 and the second surface 32 on the end surface 33. The case where the convex portion 36 located outside the member 30 is provided is described as "yes", and the case where the convex portion 36 does not protrude outward from the

boundaries

34 and 35 is described as "absent".

[Example 1]
A silicon nitride substrate (50 mm × 50 mm, thickness 0.32 mm) and a copper plate 1 (50 mm × 50 mm, thickness 0.8 mm) were prepared.
The copper plate 1 was subjected to the same masking pattern on both sides and immersed in an aqueous ferric chloride solution to etch from both sides of the copper plate and to be individualized. The copper plate 1 was cut along the diagonal line with a contour machine to expose the cross section, and the cross section was observed with a metallurgical microscope. _{When the angle θ A} formed by the lower end of the end surface 33 and the first surface 31 of the copper plate 1 was measured _{from the cross-sectional photograph, θ A} was as shown in Table 1. _{Further, when the angle θ B} formed by the upper end of the end surface 33 of the copper plate 1 and the second surface 32 was measured, it was as shown in Table 1.

A brazing paste (Ag-Cu-Ti brazing material) was prepared.
(Blazed material)
The above brazing paste was printed on a silicon nitride substrate by screen printing and dried. The brazing paste was applied so that the thickness after drying was 20 μm.
Then, the copper plate 1 was superposed on the brazing material, and the copper plate and the silicon nitride substrate were joined in a vacuum atmosphere to manufacture a ceramic circuit board.

When the appearance of the obtained ceramic circuit board was observed, it was not confirmed that the brazing material had risen on the second surface 32 of the copper plate 1.

[Examples 2 to 3, Comparative Examples 1 to 2]
The same procedure as in Example 1 was carried out except that etching was performed from both sides of the copper plate 1 to lengthen the immersion time in the ferric chloride aqueous solution to increase the angle, or to shorten the immersion time to reduce the angle. bottom. As in Example 1, there was no rise in Example 2, the degree of rise in Example 3 was small, and the rise was clearly confirmed in Comparative Examples 1 and 2.

This application claims priority based on Japanese Application Japanese Patent Application No. 2020-059763 filed on March 30, 2020, and incorporates all of its disclosures herein.

10 Ceramic substrate 11 First surface 12 Second surface 20 Brazing material 30 Metal member 31 First surface 32 Second surface 33 End surface 34 Boundary 35 Boundary 36 Convex 37 Concave 38 First curved surface 39 Second curved surface 40

Ridge line

43, 44

Inflection points

100, 101, 102 Ceramic circuit board

Claims

In a ceramic circuit board in which a plate-shaped metal member is bonded to at least one surface of a ceramic substrate via a brazing material.
The metal member has a first surface facing the ceramic substrate, a second surface opposite to the first surface, and end faces existing between the outer peripheral ends of both sides thereof.
The end face has a convex portion located outside the metal member from the boundary between the end face and the first surface or the boundary between the end face and the second surface.
The metal member is polygonal and at any of the cut surfaces in the thickness direction along its diagonal.
When the angle formed by the lower end of the end surface and the first surface is θ A ,
A ceramic circuit board that satisfies the following formula (1).
Equation (1) 0 ° <θ A <90 °
When the angle formed by the upper end of the end face and the second face is θ B ,
The ceramic circuit board according to claim 1, which satisfies the following formula (2).
Equation (2) 0 ° <θ B <90 °
In a ceramic circuit board in which a plate-shaped metal member is bonded to at least one surface of a ceramic substrate via a brazing material.
The metal member has a first surface facing the ceramic substrate, a second surface opposite to the first surface, and end faces existing between the outer peripheral ends of both sides thereof.
The end face has a recess located inside the metal member with respect to the boundary between the end face and the second face.
The end face is a ceramic circuit board having a convex portion located outside the metal member from the boundary between the end face and the first surface or the boundary between the end face and the second surface.
The ceramic circuit board according to any one of claims 1 to 3, wherein the convex portion is provided so as to orbit the entire circumference of the end face.
An electronic device including the ceramic circuit board according to any one of claims 1 to 4.
A plate-shaped metal member that is joined to one surface of a ceramic substrate with a brazing material.
The metal member has a first surface facing the ceramic substrate, a second surface opposite to the first surface, and end faces existing between the outer peripheral ends of both sides thereof.
The end face has a convex portion located outside the metal member from the boundary between the end face and the first surface or the boundary between the end face and the second surface.
The metal member is polygonal and at any of the cut surfaces in the thickness direction along its diagonal.
When the angle formed by the lower end of the end surface and the first surface is θ A ,
A metal member satisfying the following formula (1).
Equation (1) 0 ° <θ A <90 °
The metal member according to claim 6, wherein the convex portion is provided so as to orbit the entire circumference of the end face.