Insulating circuit board and method for manufacturing the same, and semiconductor module and method for manufacturing the same

Abstract

To improve the bonding strength between fine-line metal wires and circuit metal plates of insulating circuit boards.SOLUTION: In an insulating circuit board having an insulating board and a circuit metal plate bonded to at least one surface of the insulating board, the Spd value, which is the peak density of the three-dimensional surface texture parameters on the surface of the circuit metal plate, is between 100 mm-2 and 1000 mm-2, and the Sdr value, which is the ratio of the developed area of the interface to the three-dimensional surface texture parameter on the surface of the circuit metal plate, is between 0.05 and 0.2.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an insulating circuit board and a manufacturing method thereof, a semiconductor module and a manufacturing method thereof. [Background technology]

[0002] Semiconductor devices such as power modules are used to control large amounts of power in electric vehicles, trains, machine tools, etc. These power modules and other semiconductor devices generally use an insulated circuit board as a component for mounting semiconductor elements. Such an insulated circuit board has a metal circuit plate for mounting semiconductor elements bonded to the surface of an insulating substrate made of ceramics or insulating resin.

[0003] For example, Patent Document 1 describes a metal-ceramic bonded substrate (insulated circuit board) in which a copper plate or copper alloy plate is bonded to each surface of a ceramic substrate as a metal plate (circuit metal plate and heat dissipation metal plate). Patent Document 2, for example, describes a power module using an insulated circuit board that includes a power element (semiconductor element), a metal wiring plate (circuit metal plate) on the underside of the power element via a solder layer, and a heat dissipation metal plate provided on the underside of the metal wiring plate via a resin insulating layer (insulating substrate).

[0004] In mounting a power module, semiconductor elements are mounted on the surface of a circuit metal plate of an insulating circuit board and wired by wire bonding. Therefore, the surface of the circuit metal plate of an insulating circuit board for a power module is required to have excellent wire bonding properties.

[0005] As a method for obtaining a surface with excellent wire bonding properties, a method of reducing the surface roughness by chemical polishing treatment is known, as disclosed in Patent Documents 3 and 4, for example. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-51778 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-288054 [Patent Document 3] Japanese Patent Application Laid-Open No. 2007-081217 [Patent Document 4] Japanese Patent Application Publication No. 7-147465 Summary of the Invention [Problem to be solved by the invention]

[0007] In recent years, wide bandgap semiconductors such as SiC and GaN have begun to be adopted as power semiconductor elements, replacing the conventionally used Si power semiconductors. Wide bandgap semiconductor elements have a low on-resistance, making it possible to control the same amount of power as Si semiconductors with a smaller chip than conventional Si semiconductor elements.

[0008] Accordingly, metal wires used in semiconductor elements are becoming thinner from the conventionally commonly used 300 μm diameter to thinner wires, for example, 175 μm or less.

[0009] However, when the metal wire is thinned, as shown in Patent Documents 3 and 4, even if the roughness Ra (arithmetic mean roughness) of the circuit metal plate surface is set to 1.0 μm or less, or Rz (maximum height, Rmax in JIS B0601:1982) is set to 5.0 μm or less, there is a problem that the bonding strength between the metal wire and the surface of the metal plate is reduced.

[0010] Therefore, an object of the present invention is to provide a technique for improving the bonding strength between an insulating circuit board and a circuit metal plate even when a thin metal wire is used. [Means for solving the problem]

[0011] As a result of intensive research conducted by the present inventors to solve the above problems, it was confirmed that it is difficult to determine the surface properties of the metal circuit plate of an insulated circuit board that are suitable for thinned metal wires (hereinafter also referred to as thin wires) using conventional two-dimensionally evaluated line roughness (e.g., Ra, Rz, Rzjis, etc.). Conventionally, the surface roughness of the metal circuit plate of an insulated circuit board for a power module has been controlled by line roughness (e.g., Ra, Rz, etc.) measured using a stylus-type roughness tester. However, measurement using line roughness is merely a two-dimensional evaluation of one cross section of the measurement surface, and is insufficient for identifying surface properties suitable for thinned wires.

[0012] Therefore, the inventors used a laser microscope to evaluate the three-dimensional surface texture parameters of the surface of the circuit metal plate of various insulated circuit boards, and investigated the relationship between the three-dimensional surface texture parameters and the bond strength between the surface of the circuit metal plate and the thin wire in the insulated circuit board.As a result, they found that by setting the three-dimensional surface texture parameters of the surface of the circuit metal plate of the insulated circuit board within a predetermined range, good bond strength between the thin wire and the metal plate surface can be maintained.

[0013] We also discovered that a simple manufacturing method for obtaining a circuit metal plate surface with three-dimensional surface texture parameters within a specified range can be achieved by performing chemical polishing twice using a chemical polishing solution containing specified concentrations of sulfuric acid (H2SO4) and hydrogen peroxide (H2O2).

[0014] A first aspect of the present invention is An insulating circuit board comprising an insulating substrate and a circuit metal plate bonded to at least one surface of the insulating substrate, The peak density Spd value, which is a three-dimensional surface texture parameter on the surface of the circuit metal plate, is 100 mm -2 More than 1000mm -2 is as follows: The Sdr value, which is the developed area ratio of the interface of the three-dimensional surface texture parameter on the surface of the circuit metal plate, is 0.05 or more and 0.2 or less. Insulated circuit board.

[0015] A second aspect of the present invention is a method for producing a composition comprising the steps of: The arithmetic mean roughness Ra of the surface of the circuit metal plate is 0.15 μm or more and 1.5 μm or less.

[0016] A third aspect of the present invention is the first or second aspect, At a plurality of points on the surface of the circuit metal plate, the standard deviation of the Spd value is 100 mm -2 Hereinafter, the standard deviation of the Sdr value is 0.05 or less.

[0017] A fourth aspect of the present invention is any one of the first to third aspects, When Al wires with a diameter of 125 μm are bonded to the surface of the circuit metal plate, the average shear strength at a plurality of bonding points is 300 cN or more.

[0018] A fifth aspect of the present invention is any one of the first to fourth aspects, When Al wires with a diameter of 125 μm are bonded to the surface of the circuit metal plate, the first quartile of the shear strength at a plurality of bonding points is 250 cN or more.

[0019] A sixth aspect of the present invention is any one of the first to fifth aspects, When an Al wire with a diameter of 125 μm is bonded to the surface of the circuit metal plate, the interquartile range, which is the difference between the third quartile and the first quartile of the shear strength at multiple bonding locations, is 90 cN or less.

[0020] A seventh aspect of the present invention is a preparation step of preparing a bonded body including an insulating substrate and a circuit metal plate bonded to at least one surface of the insulating substrate; a first chemical polishing treatment step of treating the bonded structure with a first chemical polishing solution containing 1.0 mol / L or more and 1.6 mol / L or less of sulfuric acid and 0.7 mol / L or more and 1.2 mol / L or less of hydrogen peroxide; a second chemical polishing treatment step of treating the bonded body after the first chemical polishing treatment step with a second chemical polishing solution containing 0.04 mol / L or more and 0.4 mol / L or less of sulfuric acid and 1.0 mol / L or more and 3.0 mol / L or less of hydrogen peroxide; and a pickling step of pickling the bonded body after the second chemical polishing treatment, The peak density Spd value, which is a three-dimensional surface texture parameter on the surface of the metal plate, is 100 mm -2 More than 1000mm -2 is as follows: A method for manufacturing an insulating circuit board, wherein the Sdr value, which is the developed area ratio of three-dimensional surface texture parameters on the surface of the metal plate, is 0.05 or more and 0.2 or less.

[0021] An eighth aspect of the present invention is A semiconductor module comprising: the insulating circuit board according to any one of the first to sixth aspects; and a semiconductor element connected to the circuit metal plate by a metal wire having a diameter of 175 μm or less.

[0022] A ninth aspect of the present invention is a method for manufacturing a semiconductor device comprising: A method for manufacturing a semiconductor module, comprising connecting a semiconductor element to the circuit metal plate of the insulating circuit board of any one of the first to sixth aspects with a metal wire having a diameter of 175 μm or less. [Effects of the Invention]

[0023] According to the present invention, even if the wire is a thin wire, the bonding strength between the wire and the metal circuit plate in the insulating circuit board can be improved. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a flow diagram of a method for producing an insulating circuit board according to one embodiment of the present invention. [Figure 2] FIG. 2 is a graph showing the shear strength of Examples 1 to 3 and Reference Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0025] <One embodiment of the present invention> An embodiment of the present invention will be described below. Fig. 1 is a flow diagram of a method for producing an insulating circuit board according to one embodiment of the present invention. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits.

[0026] The insulating circuit board of the present invention includes an insulating substrate and a circuit metal plate bonded to at least one surface of the insulating substrate. In this embodiment, an insulating circuit board having a circuit metal plate on one main surface of the insulating substrate and a heat dissipation metal plate on the other main surface will be described as an example.

[0027] (insulating substrate) The insulating substrate is a plate-shaped member made of, for example, a ceramic material or a resin material. Ceramic materials used for the insulating substrate include oxide ceramics such as alumina, and non-oxide ceramics such as aluminum nitride, silicon nitride, silicon carbide, and boron nitride. Resin materials used for the insulating substrate include, for example, epoxy resin, polyurethane resin, polyimide resin, and insulating resins in which insulating ceramic filler particles such as alumina, aluminum nitride, silicon nitride, silicon carbide, and boron nitride are dispersed in a polymer resin material. The insulating substrate is preferably made of a ceramic material because it can achieve high levels of both insulation and heat dissipation performance. Among these, the insulating substrate is preferably made of a ceramic material such as alumina, aluminum nitride, or silicon nitride.

[0028] (circuit metal plate) The circuit metal plate is bonded to one main surface of the insulating substrate. The circuit metal plate is produced, for example, by bonding a raw metal plate to the insulating substrate and then forming a predetermined circuit pattern on the metal plate. As described below, the circuit metal plate is configured to have a predetermined surface shape by a predetermined chemical polishing process. As the metal plate forming the circuit metal plate, a plate-shaped member made of a pure metal or an alloy can be used. From the viewpoint of improving electrical conductivity and thermal conductivity, the metal plate is preferably made of copper or a copper alloy, or aluminum or an aluminum alloy. Note that the circuit metal plate may also be bonded to the other main surface of the insulating substrate.

[0029] (heat dissipation metal plate) The heat dissipating metal plate is bonded to the other main surface of the insulating substrate. The heat dissipating metal plate is produced, for example, by bonding a raw metal plate to the insulating substrate and then forming a predetermined heat dissipating metal pattern on the metal plate. Like the circuit metal plate, the heat dissipating metal plate may be subjected to a predetermined chemical polishing process and may be configured to have a predetermined surface shape. Note that the metal plate forming the heat dissipating metal plate may have the same composition as the metal plate forming the circuit metal plate, or may have a different composition. From the viewpoint of manufacturing efficiency, it is preferable that the respective metal plates have the same composition. Bonding the heat dissipating metal plate to the other main surface of the insulating substrate is preferable because it allows efficient heat dissipation of heat generated from semiconductor elements mounted on the insulating circuit board.

[0030] (3D surface texture parameters) In this embodiment, in order to improve the bonding strength with the metal wire, the circuit metal plate in the insulating circuit board has a predetermined value of three-dimensional surface texture parameter obtained by measuring its surface with a laser microscope. The three-dimensional surface texture parameter is a quantification of surface texture and roughness information of the circuit metal plate in a planar direction (two-dimensional surface) in a microscopic area. When the metal wire is thinned, the contact area between the surface of the circuit metal plate and the metal wire becomes smaller, and the contact state between them must be strictly controlled. The three-dimensional surface texture parameter serves as an index for ensuring the bonding strength of the metal wire. The three-dimensional surface texture parameter is measured based on ISO 25178-2:2012.

[0031] According to the investigations of the present inventors, among the three-dimensional surface texture parameters obtained when multiple locations on the surface of a circuit metal plate in an insulating circuit board are measured with a laser microscope, it has been found that the average peak density (Spd value) and the average developed area ratio (Sdr value) of the interface are parameters that have a particularly large effect on the bonding strength between the metal wire and the circuit metal plate. Here, the relationship between the surface shape of the circuit metal plate and the bonding strength will be explained.

[0032] In wire bonding to a circuit metal plate in an insulated circuit board, a metal wire is brought into contact with the circuit metal plate, pressed in with a predetermined load and pressing force, and then bonded to the circuit metal plate by, for example, applying ultrasonic waves. Since the metal wire and the circuit metal plate must be bonded in close contact, the surface roughness (uneven shape) of the circuit metal plate is important. If the surface of the circuit metal plate has many protrusions or the protrusions have a steep shape, the metal wire will ride over the protrusions, making it difficult to bond the metal wire to the metal plate. In particular, for thin wires with a diameter of 175 μm or less, the load and pressing force must be smaller than those for metal wires with a diameter of 250 μm to 500 μm in order to prevent deformation of the metal wire during bonding, making it more difficult to bond the metal wire to the circuit metal plate. Therefore, when using thin wires, the density and shape of the protrusions on the surface of the circuit metal plate become more important.

[0033] The Spd value (peak density) indicates the number of peaks (points on the surface that are higher than the surrounding adjacent points) per unit area. The smaller the Spd value, the fewer peaks (protrusions) there are on the surface of the circuit metal plate, and the larger the Spd value, the more peaks (protrusions) there are.

[0034] In this embodiment, in order to increase the bonding strength between the circuit metal plate and the metal wire, the Spd value of the circuit metal plate is set to 100 mm -2 More than 1000mm -2 The range is as follows: Spd value is 1000mm -2 If the thickness exceeds this value, the number of protrusions on the surface of the circuit metal plate will be excessively large. If the number of protrusions is excessively large, the metal wire may ride up on the protrusions, making it difficult to adhere the metal wire to the circuit metal plate, and high bonding strength cannot be achieved. In particular, when the metal wire is thinned and a metal wire (thin wire) having a diameter of, for example, 175 μm or less is bonded, the load and the amount of pressing may not be large compared to when a metal wire having a diameter of, for example, 250 μm to 500 μm is bonded. As a result, if there are many protrusions, the metal wire cannot crush the protrusions, and a sufficient bonding interface cannot be secured, which is thought to prevent high bonding strength from being obtained. On the other hand, the Spd value is 100 mm -2 If the thickness is less than 1 / 2 mm, the metal wire can be tightly attached to the circuit metal plate, but the contact area between the circuit metal plate and the metal wire becomes excessively large, which tends to excessively reduce the surface pressure during wire bonding.If the surface pressure is low, it becomes difficult to destroy the oxide film present at the bonding interface between the metal wire and the metal plate when pressing the metal wire into the circuit metal plate to perform wire bonding, and high bonding strength may not be achieved. In this respect, the Spd value is 100 mm -2 More than 1000mm -2 By keeping the value within the range below, it is possible to form a surface shape suitable for bonding fine wires on the circuit metal plate, and to increase the bonding strength. -2 Over 800mm -2 Preferably, it is less than 180 mm -2 Over 700mm-2 More preferably, the Spd value is 300 mm or less. -2 Over 400mm -2 Over 500mm -2 That's all.

[0035] The Sdr value (interface developed area ratio) indicates how much the developed area of ​​the measurement region (surface area of ​​the measured shape) has increased relative to the projected area of ​​the measurement region. The larger the Sdr value, the more protrusions there are or the shape of the protrusions is steeper, while the smaller the Sdr value, the closer the surface is to being flat, the fewer protrusions there are, and the more gentle the shape of the protrusions. A perfect surface without any protrusions will have an Sdr value of 0. The Sdr value is a value measured, for example, in accordance with ISO 25178-2:2012. Details will be described later in the Examples.

[0036] In this embodiment, from the viewpoint of increasing the bonding strength between the circuit metal plate and the metal wire, the Sdr value of the circuit metal plate is in the range of 0.05 or more and 0.2 or less. If the Sdr value exceeds 0.2, the number of protrusions on the surface of the metal circuit board will be excessive, or the shape of the protrusions will be steep. If the number of protrusions is excessively large and the shape is steep, the metal wire will climb up onto the protrusions, making it difficult to adhere the metal wire to the metal circuit board, and high bonding strength will not be achieved. On the other hand, if the Sdr value is less than 0.05, the surface of the circuit metal plate becomes nearly flat and the metal wire can be adhered to the circuit metal plate, but the contact area between the circuit metal plate and the metal wire becomes excessively large, reducing the surface pressure, making it difficult to destroy the oxide film present at the bonding interface, and it may not be possible to achieve high bonding strength. In this regard, when the Sdr value is in the range of 0.05 to 0.2, a surface shape suitable for bonding thin wires can be formed on the circuit metal plate, and bonding strength can be increased. The Sdr value is preferably 0.08 to 0.15, and more preferably 0.1 to 0.14.

[0037] (arithmetic mean roughness) The arithmetic mean roughness Ra of the circuit metal plate of the insulating circuit board is not particularly limited as long as the Spd and Sdr values ​​satisfy the above ranges, but is preferably 0.15 μm to 1.5 μm, more preferably 0.3 μm to 1.1 μm, even more preferably 0.4 μm to 1.0 μm, and even more preferably 0.5 μm to 0.8 μm. By ensuring that the arithmetic mean roughness Ra of the surface of the metal plate falls within the specified range, it is possible to increase the bonding strength during wire bonding.

[0038] (area distribution) On the surface of the circuit metal plate of the insulating circuit board, it is preferable that the in-plane variation of the Spd value and Sdr value on the surface of the circuit metal plate is small in order to suppress the in-plane variation of the bonding strength between the circuit metal plate and the metal wire. Specifically, when measuring the surface of the circuit metal plate at multiple points with a laser microscope, the standard deviation of the Spd value is 100 mm -2 It is preferable that the coefficient of variation of the Spd value is 12% or less, and the standard deviation of the Sdr value is preferably 0.05 or less. This makes it possible to reduce the variation in the bond strength when wire bonding is performed at multiple locations on the surface of the circuit metal plate, and to prevent the occurrence of locations where the bond strength is locally low. Furthermore, the coefficient of variation of the Spd value is preferably 12% or less, and more preferably 10% or less. Furthermore, the coefficient of variation of the Sdr value is preferably 23% or less, and more preferably 20% or less. The coefficient of variation of the Spd value is calculated using the following formula (1), and the coefficient of variation of the Sdr value is calculated using the following formula (2). Spd variation coefficient (%) = 100 × [Spd standard deviation σ] / [Spd mean value] (1) Sdr variation coefficient (%) = 100 × [standard deviation of Sdr σ] / [average value of Sdr] (2)

[0039] (2) Semiconductor module The semiconductor module is constructed by connecting semiconductor elements to the circuit metal plate of the insulating circuit board by metal wires.

[0040] Examples of metal wires that can be used include Al wires containing aluminum, Au wires containing gold, and Cu wires containing copper. Al wires are preferred from the viewpoint of achieving both cost and moisture resistance. The diameter of the metal wire is not particularly limited, but in this embodiment, the surface of the metal plate is formed so that the Spd and Sdr values ​​are within a predetermined range, so that high bonding strength can be achieved even when using thin wires with a diameter of 175 μm or less. The diameter of the thin wire is preferably 175 μm or less, and more preferably 100 μm or more and 175 μm or less.

[0041] Furthermore, in a semiconductor module using the insulating circuit board of the present invention, when a metal wire (e.g., an Al wire) having a diameter of 125 μm is bonded to the surface of the metal plate of the insulating circuit board, the shear strength at each of the bonding locations is high. Specifically, the average shear strength at the bonding locations is preferably 300 cN or more.

[0042] Furthermore, in a semiconductor module, the variation in Spd and Sdr values ​​on the surface of the metal plate is small, so when a metal wire (e.g., an Al wire) with a diameter of 125 mm is bonded to the surface of the metal plate, the variation in shear strength at multiple bonding locations is small. Specifically, it is preferable that the first quartile of the shear strength at multiple bonding locations is 250 cN or greater. It is also preferable that the interquartile range, which is the difference between the third and first quartiles of the shear strength at multiple bonding locations, is 90 cN or less.

[0043] (3) Manufacturing method for insulating circuit boards Next, a method for manufacturing the above-mentioned insulating circuit board will be described. Here, as an example, a metal-ceramic circuit board will be described, in which a circuit metal plate is bonded to one main surface of a ceramic substrate, which is an insulating substrate, and a heat dissipation metal plate is bonded to the other main surface.

[0044] (preparation process) First, a bonded assembly is prepared in which a circuit metal plate and a heat dissipation metal plate are bonded to the main surface of a ceramic substrate. The bonded assembly can be produced, for example, as follows.

[0045] Specifically, first, metal plates are bonded to both main surfaces of a ceramic substrate. Known bonding methods, such as direct bonding, brazing, and adhesive bonding, can be used. Brazing is particularly suitable because it produces fewer voids at the interface between the ceramic substrate and the metal plate and provides a bonding layer (brazing material bonding layer) formed between the ceramic substrate and the metal plate with excellent thermal cycling resistance. When brazing is used as the bonding method, a laminate is prepared in which a brazing material is disposed between the ceramic substrate and the metal plate, and the laminate is heated to a predetermined temperature, for example, a temperature at which a liquid phase is generated from the brazing material, and then cooled.

[0046] Next, a predetermined pattern is formed on each of the metal plates bonded to both main surfaces of the ceramic substrate. For example, an etching resist film having a predetermined circuit pattern is formed on the surface of the metal plate bonded to one main surface of the insulating substrate, and an etching resist film having a predetermined heat dissipation metal pattern is formed on the surface of the metal plate bonded to the other main surface. These resist films may be formed by forming a resist using a known method such as screen printing, laminating, or photomasking, and then curing it.

[0047] Next, the areas of the metal plate not covered with the resist film are removed using a known etching solution, such as cupric chloride, iron chloride, hydrofluoric acid, or a chelating agent, and then the resist film is removed. Furthermore, if the bonded body is produced by a brazing method, the unnecessary brazing material bonding layer between the patterns is removed. This results in a bonded body in which a circuit metal plate having a predetermined circuit pattern and a heat dissipation metal plate having a predetermined heat dissipation metal pattern are bonded to both main surfaces of the ceramic substrate.

[0048] (First chemical polishing process) Next, the bonded body is subjected to a chemical polishing treatment using a chemical polishing solution containing sulfuric acid and hydrogen peroxide. In this embodiment, first and second chemical polishing treatments are performed using two types of first and second chemical polishing solutions with different concentrations of sulfuric acid and hydrogen peroxide. Note that in this embodiment, the first and second chemical polishing treatments are performed on the circuit metal plate and heat dissipation metal plate of the bonded body, but it is sufficient to perform the first and second chemical polishing treatments at least on the circuit metal plate to be wire-bonded.

[0049] The first chemical polishing step is performed to remove oxide layers, hydroxide layers, and scratches caused during handling that have formed on the surfaces of the circuit metal plate and the heat dissipation metal plate prior to the first chemical polishing step, and to uniformly form a surface shape suitable for the second chemical polishing step described below. In the first chemical polishing step, a first chemical polishing solution is brought into contact with the surfaces of the circuit metal plate and the heat dissipation metal plate of the assembly. The first chemical polishing solution forms a metal oxide layer on the surfaces of the circuit metal plate and the heat dissipation metal plate through the oxidizing action of hydrogen peroxide, and the metal oxide layer can be dissolved by sulfuric acid. As a result, portions of the surfaces of the circuit metal plate and the heat dissipation metal plate are dissolved in the thickness direction, removing the oxide layers, hydroxide layers, and scratches that have formed on the surfaces of the circuit metal plate and the heat dissipation metal plate.

[0050] The first chemical polishing solution contains 1.0 mol / L to 1.6 mol / L of sulfuric acid and 0.7 mol / L to 1.2 mol / L of hydrogen peroxide. The first chemical polishing solution preferably contains 1.2 mol / L to 1.5 mol / L of sulfuric acid. The first chemical polishing solution also preferably contains 0.8 mol / L to 1.1 mol / L of hydrogen peroxide. Compared to the second chemical polishing solution described below, the first chemical polishing solution contains a higher concentration of sulfuric acid and a lower concentration of hydrogen peroxide. Because the first chemical polishing solution has a high dissolution and removal rate due to sulfuric acid, it preferentially dissolves and removes easily soluble portions (e.g., grain boundaries) and easily soluble crystal orientations of the metal plate. As a result, the surfaces of the circuit metal plate and the heat dissipation metal plate can be roughly polished.

[0051] The first chemical polishing solution may contain a stabilizer for hydrogen peroxide in addition to sulfuric acid and hydrogen peroxide. The stabilizer can suppress decomposition of hydrogen peroxide, maintain the oxidizing power of hydrogen peroxide, and extend the life of the first chemical polishing solution. Examples of stabilizers that can be used include linear polyhydric alcohols such as ethylene glycol and glycerin, phenols, acetamides, and benzamides. Among these, ethylene glycol and glycerin are preferred because they are highly soluble in water, have low toxicity, and are easy to handle. The concentration of the stabilizer is not particularly limited, but is preferably 0.1 mol / L to 0.5 mol / L.

[0052] The method for bringing the first chemical polishing liquid into contact with the metal plate of the joined body can be a conventionally known method, such as an immersion treatment method in which the joined body is immersed in the first chemical polishing liquid, or a spray treatment method in which the first chemical polishing liquid is sprayed in the form of a spray or shower.

[0053] As a processing condition for the first chemical polishing, the temperature of the first chemical polishing solution is preferably 30°C to 60°C, more preferably 40°C to 60°C. Since the lower the sulfuric acid concentration in the first chemical polishing solution, the slower its reactivity tends to be. Therefore, it is recommended to increase the temperature according to the concentration to enhance reactivity. In this regard, by setting the temperature of the first chemical polishing solution within the above range, oxide layers, hydroxide layers, and scratches on the metal plate can be stably dissolved and removed. Furthermore, the contact time with the first chemical polishing solution (e.g., immersion time) is not particularly limited as long as it can dissolve and remove the oxide layers, hydroxide layers, and scratches formed on the surface of the metal plate. It can be suitably adjusted depending on the thickness of the oxide layers, hydroxide layers, and the depth of scratches. The thickness of the oxide layers, hydroxide layers, and the depth of scratches are, for example, 10 μm to 50 μm. Therefore, to dissolve and remove such oxide layers, hydroxide layers, and scratches, the contact time is preferably 270 seconds to 390 seconds. When the thickness of the oxide layers, hydroxide layers, and the depth of scratches exceed 50 μm, it is recommended to extend the contact time.

[0054] After the first chemical polishing treatment, the bonded body is preferably washed with water. This washes away the first chemical polishing solution adhering to the metal plate and stops any further reaction. The water washing method can be, for example, an immersion treatment method or a spray treatment method. The temperature of the water used for washing is preferably in the range of, for example, 4°C to 30°C, from the viewpoint of suppressing deterioration of the metal plate.

[0055] (Second chemical polishing process) Next, the metal plates of the bonded body that have been subjected to the first chemical polishing treatment are brought into contact with a second chemical polishing solution to chemically polish the surfaces of the metal plates. The second chemical polishing treatment allows the surface of the metal plate that has been roughly chemically polished by the first chemical polishing treatment to be precisely dissolved and removed. This allows the surface of the metal plate to be formed into a shape suitable for bonding thin wires, with Spd and Sdr values ​​within predetermined ranges.

[0056] The second chemical polishing liquid has a lower sulfuric acid concentration and a higher hydrogen peroxide concentration than the first chemical polishing liquid. Specifically, the second chemical polishing liquid contains 0.04 mol / L to 0.4 mol / L of sulfuric acid and 1.0 mol / L to 3.0 mol / L of hydrogen peroxide. The second chemical polishing liquid preferably contains 0.05 mol / L to 0.1 mol / L of sulfuric acid. The second chemical polishing liquid preferably contains 1.5 mol / L to 2.7 mol / L of hydrogen peroxide, more preferably 1.9 mol / L to 2.4 mol / L of hydrogen peroxide. The second chemical polishing liquid has a gentler dissolution and removal action than the first chemical polishing liquid because the formation of a metal oxide layer occurs more preferentially due to the oxidizing action of hydrogen peroxide. With such a second chemical polishing liquid, the diffusion rate of ions contributing to dissolution is rate-determining, and it is presumed that dissolution of three-dimensional protrusions present on the metal plate occurs preferentially over dissolution of the surface of the metal plate. In other words, the second chemical polishing solution can preferentially dissolve the protrusions on the metal plate, making it possible to process the metal plate into a flatter surface.

[0057] Like the first chemical polishing solution, the second chemical polishing solution may contain a stabilizer for hydrogen peroxide in addition to sulfuric acid and hydrogen peroxide. The stabilizer may be the same as that used in the first chemical polishing solution, and preferably at least one of ethylene glycol and glycerin. The concentration of the stabilizer is not particularly limited, but is preferably 0.1 mol / L to 0.5 mol / L.

[0058] As in the first chemical polishing treatment, the method for bringing the second chemical polishing solution into contact with the metal plate of the bonded body can be a conventionally known method such as an immersion treatment method or a spray treatment method. When a spray treatment method is used, it is preferable to reduce the spray rate because the metal oxide layer produced during the reaction in the second chemical polishing treatment may fall off due to the impact of the spray.

[0059] As a processing condition for the second chemical polishing, the temperature of the second chemical polishing solution is preferably 30°C to 60°C, and more preferably 40°C to 60°C. Since the lower the concentration of sulfuric acid in the second chemical polishing solution, the slower its reactivity tends to be, it is advisable to increase the temperature according to the concentration to enhance reactivity. In this regard, by setting the temperature of the second chemical polishing solution within the above range, protrusions on the metal plate can be stably dissolved and removed, achieving the desired surface condition. Furthermore, the contact time with the second chemical polishing solution (e.g., immersion time) can be appropriately adjusted so that the Spd and Sdr values ​​on the surface of the metal plate fall within a predetermined range. The contact time is preferably 330 to 450 seconds.

[0060] (pickling process) Next, the bonded body after the second chemical polishing treatment is brought into contact with a pickling solution and pickled. A metal oxide layer may remain on the surface of the metal plate after the second chemical polishing treatment. For example, if the metal plate is copper, hydrogen peroxide may oxidize the copper during the second chemical polishing treatment, leaving a thin, sparse oxide layer mainly composed of copper (II) oxide. If the bonded body is washed with water without pickling, the metal oxide layer may fall off, resulting in a rough surface of the metal plate. In this regard, pickling can dissolve and remove the remaining metal oxide layer, for example, an oxide layer mainly composed of copper (II) oxide.

[0061] The pickling solution used for pickling is not particularly limited as long as it dissolves and removes the metal oxide layer without excessively dissolving the substrates of the circuit metal plate and the heat dissipation metal plate, but it is preferable to use dilute sulfuric acid or dilute hydrochloric acid. When dilute sulfuric acid is used as the pickling solution, it is preferable to set the sulfuric acid concentration to 0.5 mol / L to 2.0 mol / L.

[0062] As in the first chemical polishing treatment, the contact method with the pickling solution can be a conventionally known method such as an immersion treatment method or a spray treatment method. When a spray treatment method is used, it is preferable to reduce the spray rate in order to prevent the metal oxide layer from falling off due to the impact of the spray.

[0063] As a condition for pickling, the temperature of the pickling solution is preferably 4°C to 30°C from the viewpoint of suppressing deterioration of the surfaces of the surface-prepared circuit metal plate and heat dissipation metal plate underlying the metal oxide layer. The pickling treatment time is not particularly limited as long as it can dissolve and remove the remaining metal oxide layer. In the case of an immersion treatment method, the immersion time is preferably 10 to 20 seconds.

[0064] (Cleaning process) Next, the bonded body after the second chemical polishing treatment is washed to remove impurities present on the surfaces of the circuit metal plate and the heat dissipation metal plate of the bonded body.

[0065] The cleaning method is preferably water washing or pure water washing, and conventionally known methods such as immersion treatment or spray treatment can be used, as in the first chemical polishing treatment step, etc. The liquid temperature for water washing or pure water washing is preferably in the range of 4°C to 30°C.

[0066] In this manner, a metal ceramic circuit substrate is obtained as the insulating circuit substrate of this embodiment.

[0067] A semiconductor module is fabricated using the above-described insulating circuit board. Specifically, first, a semiconductor element is placed on the insulating circuit board. Next, one end of a prepared metal wire is brought into close contact with an electrode of the semiconductor element, and they are wire-bonded by, for example, applying ultrasonic waves. Next, the other end of the metal wire is brought into close contact with a circuit metal plate of the insulating circuit board, and they are wire-bonded by, for example, applying ultrasonic waves. In this manner, a semiconductor module can be manufactured.

[0068] <Other Embodiments of the Present Invention> Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments and can be modified in various ways without departing from the spirit of the present invention.

[0069] In the above-described embodiment, the first and second chemical polishing processes are performed on the prepared assembly. However, other processes may be performed as needed. For example, if oil or grease adheres to the surface of the metal plate of the prepared assembly, a known degreasing process may be performed before the first chemical polishing process. Furthermore, if metal oxide scale or the like is present on the surfaces of the circuit metal plate and heat dissipation metal plate of the prepared assembly, a known pickling process may be performed before the first chemical polishing process. Furthermore, for example, after the above-described pickling process, additional surface treatments may be performed to further impart functionality to the surfaces of the circuit metal plate and heat dissipation metal plate of the insulating circuit board, as long as the three-dimensional surface properties of the metal plate are not impaired. Specifically, an anti-rust film or various plating films may be formed on the surfaces of the circuit metal plate and heat dissipation metal plate.

[0070] In the above-described embodiment, an etching method is used to form the circuit metal plate and the heat dissipation metal plate of the insulated circuit board, but the present invention is not limited to this. For example, a metal plate may be punched in advance into a predetermined circuit pattern shape or a heat dissipation metal pattern shape, and then bonded to an insulating layer (made of insulating ceramics or insulating resin material) by a known method (such as direct bonding or brazing if the insulating layer is made of insulating ceramics, or a method of hot pressing via a thermosetting resin layer or a thermoplastic resin layer if the insulating layer is made of insulating resin material, or an adhesive bonding method using various adhesives) to form the circuit metal plate and the heat dissipation metal plate of the insulated circuit board.

[0071] In the above embodiment, the chemical polishing step is performed consecutively after the metal pattern formation step by etching, but the chemical polishing step can be performed at any timing as long as it does not impair the obtained three-dimensional surface texture. For example, when pattern formation is performed by the mounting method, the chemical polishing step may be performed on the punched circuit metal plate and heat dissipation metal plate before they are bonded to the insulating layer.

[0072] In the above-described embodiment, an insulating circuit board is described in which metal plates are formed on both main surfaces of a single insulating layer, but the insulating layer may be multiple layers.Furthermore, the insulating circuit board may have only a circuit metal plate and no heat dissipation metal plate.

[0073] In the above-described embodiment, the chemical polishing process of the present invention was applied to the entire surfaces of both the circuit metal plate and the heat dissipation metal plate of the insulated circuit board, but when the insulated circuit board is mounted as a power module, the chemical polishing process does not need to be applied to areas where wire bonding is not performed (non-wire bonding areas). For example, by protecting the non-wire bonding areas with a resist film or the like before the chemical polishing process, an insulated circuit board can be obtained in which the wire bonding areas have the three-dimensional surface texture of the present invention, but the other surfaces of the circuit metal plates have surface texture suitable for other mounting processes. [Example]

[0074] The present invention will be explained in more detail below with reference to Examples and Reference Examples, but the present invention is not limited to these examples in any way.

[0075] (1) Preparation of an insulated circuit board First, an insulated circuit board was fabricated. Specifically, an aluminum nitride (AlN) substrate measuring 58 mm long, 50 mm wide, and 1 mm thick was prepared. Copper plates measuring 58 mm long, 50 mm wide, and 0.3 mm thick were brazed to both sides of each AlN substrate using Ag-Cu-Ti brazing filler (Ag:Cu:Ti = 88:10:2). Next, etching resists with predetermined patterns were formed on each of the copper plates bonded to the AlN substrate by screen printing. Unnecessary copper plate portions were then etched away using an etching solution containing copper chloride, and the etching resist was peeled off and removed using a sodium hydroxide solution. The unnecessary brazing material bonding layer was then etched away using an etching solution containing EDTA, and copper circuit metal plates and copper heat dissipation metal plates were formed on both sides of the AlN substrate to produce a bonded assembly.

[0076] Twenty-four bonded bodies obtained in this way before the chemical polishing treatment step were prepared, and these were randomly divided into four equal parts, to obtain four sets of bonded bodies, each consisting of six pieces.

[0077] In this example, each of the produced bonded bodies was subjected to chemical polishing treatment under the following conditions to produce an insulating circuit board.

[0078] Example 1 In Example 1, first, a chemical bath containing 1.4 mol / L of sulfuric acid, 0.9 mol / L of hydrogen peroxide, and 0.4 mol / L of ethylene glycol as a stabilizer was prepared as a first chemical polishing solution, with a liquid temperature of 45°C. A chemical bath containing 0.06 mol / L of sulfuric acid, 2.15 mol / L of hydrogen peroxide, and 0.2 mol / L of ethylene glycol as a stabilizer was prepared as a second chemical polishing solution, with a liquid temperature of 50°C. A chemical bath containing 1.0 mol / L of sulfuric acid and room temperature was prepared as a pickling solution. 4 L of each chemical solution was prepared. The compositions of each chemical solution are summarized in Table 1 below.

[0079] Next, one bonded body was immersed in a first chemical polishing solution for 300 seconds, rinsed with water, immersed in a second chemical polishing solution for 400 seconds, then immersed in a pickling solution for 15 seconds, and finally rinsed with water and pure water to produce an insulating circuit board of Example 1. The water rinsing and pure water rinsing were also performed by immersion treatment.

[0080] [Table 1]

[0081] Example 2 In Example 2, as shown in Table 1, a chemical bath containing sulfuric acid at a concentration of 0.055 mol / L, hydrogen peroxide at a concentration of 2.1 mol / L, and ethylene glycol at a concentration of 0.2 mol / L was used as the second chemical polishing solution, and the solution temperature was 50°C. The insulating circuit board of Example 2 was produced by carrying out the same process as in Example 1.

[0082] Example 3 In Example 3, as shown in Table 1, a chemical bath containing sulfuric acid at a concentration of 0.065 mol / L, hydrogen peroxide at a concentration of 2.2 mol / L, and ethylene glycol at a concentration of 0.2 mol / L was used as the second chemical polishing solution, and the solution temperature was 50°C. The insulating circuit board of Example 3 was produced by carrying out the same process as in Example 1.

[0083] (Reference example 1) In Reference Example 1, as shown in Table 1, a chemical bath containing 0.75 mol / L of sulfuric acid, 0.94 mol / L of hydrogen peroxide, and 0.26 mol / L of ethylene glycol as the second chemical polishing solution was used, and the solution temperature was 35°C. The immersion time was 60 seconds. In Reference Example 1, the second chemical polishing solution had a higher sulfuric acid concentration and a lower hydrogen peroxide concentration than those in Examples 1 to 3. Therefore, if the solution was treated at 50°C, the same as in Examples 1 to 3, an excessive amount of material would be dissolved and removed. Therefore, to suppress the dissolving and removing effect, the solution temperature in Reference Example 1 was set to 35°C.

[0084] (2) Evaluation method The insulating circuit boards produced in Examples 1 to 3 and Reference Example 1 obtained above were used as samples to evaluate line roughness, three-dimensional surface texture parameters, wire bonding, and shear strength. Each evaluation method is explained below.

[0085] (Line roughness evaluation) For line roughness evaluation, surface roughness measurement was performed based on JIS B0601-2001. The measurement device used was a stylus-type roughness meter "SURFTEST SJ-210" manufactured by Mitutoyo Corporation. A stylus with a tip radius of 2 μm and a conical taper angle of 60° was used, and the measurement conditions were cutoff value λc: 0.8 mm, cutoff value λs: 2.5 μm, reference length: 0.8 mm, and evaluation length (= measurement length): 4 mm. Two types of roughness parameters were evaluated: Ra (arithmetic mean roughness) and Rz (maximum height). Measurements were performed at four randomly selected locations on the surface of the circuit metal plate per substrate. Since there were six samples in each Example and Reference Example, measurements were performed at a total of 24 locations (6 sheets x 4 locations). Table 2 shows the average values ​​of Ra (arithmetic mean roughness) and Rz (maximum height) from the measurement results.

[0086] (3D surface texture parameter evaluation) Three-dimensional surface texture parameters were evaluated based on ISO 25178-2:2012. A laser microscope "VK-X1100" (Keyence Corporation) was used as the measurement device. Laser confocal images were captured using a 5x objective lens, and three-dimensional surface texture parameters were calculated using the analysis software "VK-X Series Multi-File Analysis Application." The captured image size was 2,784 μm × 2,088 μm (1024 × 768 pixels). The analysis software's measurement conditions were as follows: the entire measurement area of ​​the captured image, filter type: Gaussian, S-filter: 10 μm, F-operation: None, L-filter: 2 mm, and end effect correction: Enabled. Two three-dimensional surface texture parameters were measured: Spd value (peak density) and Sdr value (interface developed area ratio). Measurements were taken at four randomly selected locations on the circuit metal plate surface per sample. Since there were six samples in each Example and Reference Example, measurements were taken at 24 locations in total (6 samples x 4 locations). Table 2 shows the average values ​​of the measurement results.

[0087] (Wire bonding and shear strength evaluation) To evaluate the bonding strength of the metal wire, wire bonding was performed on each sample, and the bonding strength between the metal wire and the surface of the metal plate was evaluated by shear strength measurement. The metal wire used was a thin aluminum wire with a diameter of 125 μm, "TANW-Soft1 φ125 STD" (manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.), and the bond tester "Model 5600-C" (manufactured by F&K Delvotec) was used for wire bonding and shear strength measurement. Specifically, first, a "Model 5650" was used as the bonding head of the bond tester, and the wire bonding conditions were US Time: 50 ms, US Power: 45 digits, B-Force Start: 40 cN, B-Force End: 70 cN, TD Steps: 67 μm, and the wire loop conditions were Loop Mode: No Reverse, Loop Form: Triangular, Z-Presign: 35%, Loop H-Factor: 160%, XY Loop H-Factor: 25%, Z-Delay: 50%. Wire bonding was performed on the metal plate of the insulated circuit board so that the distance between the first bond and the second bond was 3 mm, and two Al wire loops were formed per insulated circuit board. Next, using the "SH-5000C" as the shear strength measurement head of the bond tester, the shear strength was measured on the 1st and 2nd bonds of the two Al wire loops, with a test speed of 300 μm / s and a shear height of 15 μm. Measurements were taken at four locations per sample. In this case, measurements were taken at a total of 24 locations per batch (6 samples x 4 locations). The average, maximum, third quartile, median, first quartile, and minimum values ​​obtained from the measurement results of the shear strength of each of the first and second bonds are shown in Table 3. Also, a graph of the shear strength of Examples 1 to 3 and the Reference Example is shown in Figure 2.

[0088] [Table 2]

[0089] [Table 3]

[0090] (3) Evaluation results As shown in Table 2, it was confirmed that the arithmetic mean roughness Ra was in the range of 0.1 μm to 1.0 μm and the maximum height Rz was in the range of 1.0 μm to 5.0 μm in Examples 1 to 3 and Reference Example 1. On the other hand, with regard to the three-dimensional surface texture parameters of the surface of the metal plate, in Examples 1 to 3, the average Spd value was 100 mm -2 More than 1000mm -2 On the other hand, in Reference Example 1, the average Spd value was 1723 mm -2 and 1000 mm -2 It was confirmed that the average Sdr value was greater than 0.2. Furthermore, in Examples 1 to 3, the average Sdr value was 0.05 to 0.2, while in Reference Example 1 it was 0.511, which was greater than 0.2. In other words, although Reference Example 1 had a line roughness similar to that of Example 1 and the like, the density of protrusions was higher and the shape of the protrusions was steeper than that of Example 1 and the like. From this, it was confirmed that even when the line roughness values ​​were similar, the density and shape of the protrusions were significantly different when the surface was measured three-dimensionally.

[0091] In Examples 1 to 3, chemical polishing was performed using a second chemical polishing solution with a relatively low sulfuric acid concentration of 0.06 [mol / L], 0.055 [mol / L], or 0.065 [mol / L]. This allowed the protrusions remaining during the first chemical polishing to be dissolved and removed, presumably resulting in the Spd and Sdr values ​​on the surface of the metal plate being adjusted to within the specified range. In contrast, in Reference Example 1, a second chemical polishing solution with a sulfuric acid concentration of 0.75 [mol / L], a higher concentration than in Example 1, was used. It was confirmed that the Spd and Sdr values ​​could not be adjusted to within the specified range. This is presumably because the high reactivity of sulfuric acid caused not only the protrusions but also the flat surfaces of the metal plate to be dissolved and removed.

[0092] Furthermore, as shown in Table 2, in Reference Example 1, the standard deviation of the Spd value was 236 mm -2 The standard deviation of the Sdr value was 0.140, and it was confirmed that the density and shape of the protrusions varied widely on the surface of the metal plate and were not uniform. In contrast, in Examples 1 to 3, the standard deviation of the Spd value was 100 mm. -2Hereinafter, it was confirmed that the standard deviation of the Sdr values ​​was 0.05 or less, and that there was little variation in the density and shape of the protrusions on the surface of the metal plate. Furthermore, the coefficient of variation of the Spd values ​​was 12% or less in Examples 1 to 3, while it was 13.7% in Reference Example 1, confirming that the variation in the Spd values ​​was small in Examples 1 to 3. Similarly, the coefficient of variation of the Sdr values ​​was 20% or less in Examples 1 to 3, while it was 27.3% in Reference Example 1, confirming that the variation in the Sdr values ​​was small in Examples 1 to 3.

[0093] Furthermore, as shown in Table 3, the shear strengths of Examples 1 to 3 and Reference Example 1 when wire-bonded to a metal plate were measured. In Reference Example 1, the average shear strength at 24 bonding locations was 249 cN, confirming a tendency for low wire bond strength. Furthermore, the minimum shear strength at multiple bonding locations was 200 cN, and the first quartile of shear strength was 214 cN, confirming the occurrence of many locations with low bond strength. Furthermore, the interquartile range, which is the difference between the first and third quartiles, was high at 97 cN, confirming that the shear strength at multiple bonding locations varied widely, i.e., the bond strength varied widely. Specifically, as shown in FIG. 2, Reference Example 1 exhibited a large variation in shear strength. Note that FIG. 2 is a graph showing the shear strengths of Examples 1 to 3 and Reference Example 1. Figure 2 shows a box plot of the share intensity for each example. The bottom of the whiskers indicates the minimum value of share intensity, the top of the whiskers indicates the maximum value, the bottom of the box indicates the first quartile, the top of the box indicates the third quartile, the line inside the box indicates the median (second quartile), and the × (marked ×) indicates the mean value.

[0094] In contrast, in Examples 1 to 3, the Spd and Sdr values ​​on the surface of the metal plate were within the specified range, so the average shear strength was 300 cN or higher, confirming a tendency for high wire bond strength. Furthermore, as shown in Figure 2, the minimum shear strength value at multiple bonding locations was 260 cN or higher, and the first quartile of shear strength was 260 cN or higher, confirming that there were few locations where bond strength was extremely low. Furthermore, the interquartile range was 90 cN or less, confirming that there was little variation in shear strength at multiple bonding locations, i.e., there was little variation in bond strength.

[0095] As described above, by chemically polishing a metal plate using two chemical polishing solutions with different concentrations of sulfuric acid and hydrogen peroxide, the Spd and Sdr values ​​of the metal plate of an insulating circuit board can be adjusted to fall within a predetermined range. As a result, the bonding strength between the metal plate and the insulating circuit board can be improved even for thin wires.

Claims

1. An insulating circuit board comprising an insulating substrate and a circuit metal plate bonded to at least one surface of the insulating substrate, The Spd value, which is the peak density of the three-dimensional surface texture parameter on the surface of the circuit metal plate, is 100 mm －２ More than 1000mm －２ is as follows: the Sdr value, which is the developed area ratio of the interface of the three-dimensional surface texture parameter on the surface of the circuit metal plate, is 0.05 or more and 0.2 or less; Insulated circuit board.

2. The arithmetic mean roughness Ra of the surface of the circuit metal plate is 0.15 μm or more and 1.5 μm or less. The insulating circuit board according to claim 1 .

3. At a plurality of points on the surface of the circuit metal plate, the standard deviation of the Spd value is 100 mm －２ The standard deviation of the Sdr value is 0.05 or less.

3. The insulating circuit board according to claim 1 or 2.

4. When an Al wire having a diameter of 125 μm is bonded to the surface of the circuit metal plate, the average shear strength at a plurality of bonding points is 300 cN or more.

3. The insulating circuit board according to claim 1 or 2.

5. When an Al wire having a diameter of 125 μm is bonded to the surface of the circuit metal plate, the first quartile of the shear strength at a plurality of bonding points is 250 cN or more.

3. The insulating circuit board according to claim 1 or 2.

6. When an Al wire having a diameter of 125 μm is bonded to the surface of the circuit metal plate, the interquartile range, which is the difference between the third quartile and the first quartile of the shear strength at a plurality of bonding points, is 90 cN or less.

3. The insulating circuit board according to claim 1 or 2.

7. a preparation step of preparing a bonded body including an insulating substrate and a circuit metal plate bonded to at least one surface of the insulating substrate; a first chemical polishing treatment step of treating the bonded structure with a first chemical polishing solution containing 1.0 mol / L or more and 1.6 mol / L or less of sulfuric acid and 0.7 mol / L or more and 1.2 mol / L or less of hydrogen peroxide; a second chemical polishing step of treating the bonded body after the first chemical polishing step with a second chemical polishing solution containing 0.04 mol / L or more and 0.4 mol / L or less of sulfuric acid and 1.0 mol / L or more and 3.0 mol / L or less of hydrogen peroxide; and a pickling step of pickling the bonded body after the second chemical polishing treatment, The Spd value, which is the peak density of the three-dimensional surface texture parameter on the surface of the metal plate, is 100 mm －２ More than 1000mm －２ is as follows: The method for manufacturing an insulating circuit board, wherein the Sdr value, which is a developed area ratio of three-dimensional surface texture parameters on the surface of the metal plate, is 0.05 or more and 0.2 or less.

8. 3. A semiconductor module comprising: the insulating circuit board according to claim 1; and a semiconductor element connected to the circuit metal plate by a metal wire having a diameter of 175 μm or less.

9. 3. A method for manufacturing a semiconductor module, comprising connecting a semiconductor element to the circuit metal plate of the insulating circuit board according to claim 1 or 2 with a metal wire having a diameter of 175 μm or less.

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