KR102343189B1 - Insulation substrate and method for manufacturing the same - Google Patents

Abstract

The present invention relates to an insulating substrate in which a ceramic substrate, a first copper plate formed on one surface of the ceramic substrate, and a second copper plate formed on the other surface of the ceramic substrate are bonded. Each copper plate has a composition in which the total content of metal components selected from Al, Be, Cd, Mg, Pb, Ni, P, Sn and Cr is 0.1 to 2.0 ppm, and the copper content is 99.96 mass% or more, and the surface of each copper plate When the crystal orientation distribution function obtained through the texture analysis by the EBSD of The average value of the orientation density in is 0.1 or more and less than 15.0, and the average value of the orientation density in the range of φ1 = 20 ° to 40 °, Φ = 55 ° to 75 °, and φ2 = 20 ° is 0.1 or more and less than 15.0, and The average crystal grain diameter of each copper plate material is 50 micrometers - 400 micrometers.

Description

Insulation substrate and method for manufacturing the same

The present invention relates to an insulating substrate, particularly an insulating substrate for a power supply device, and a method for manufacturing the same.

In general, since a power supply device uses a high voltage and a large current, it is necessary to solve the deterioration of material properties due to the heat generated by the semiconductor element. Therefore, in recent years, measures for insulation and heat dissipation using an insulating substrate obtained by bonding a ceramic substrate excellent in insulation and heat dissipation to a copper plate have been devised.

When bonding a ceramic substrate and a copper plate, a bonding method of bonding using a silver brazing material or the like, a bonding method of bonding using a copper eutectic reaction without using a brazing material, etc. are mainly used. Aluminum nitride, alumina, silicon nitride, etc. are used for a ceramic substrate, but these thermal expansion coefficients differ from the thermal expansion coefficient of the copper plate material which comprises a copper plate. For this reason, there is a tendency that a large deformation occurs in the entire insulating substrate due to a difference in the coefficient of thermal expansion during heat generation of the semiconductor device. In addition, in the ceramic substrate and the copper plate, since the copper plate has a higher coefficient of thermal expansion, when heat treatment is performed, tensile stress is applied to the ceramic substrate and compressive stress is applied to the copper plate. Due to this, a high strain is applied to the entire insulating substrate, and the insulating substrate is deformed by thermal expansion to change the dimensions, and the ceramic substrate and the copper plate are easily peeled off. Accordingly, there is a need for an insulating substrate that is not deformed as much as possible even when heated.

In addition, in high-purity copper used for a copper plate, crystal grains grow large at a high temperature of 700° C. or more during bonding, so that the structure is not homogeneous, and the elongation and tensile strength are also reduced. For this reason, there is a problem in that the bonding property is lowered, and when deformation occurs, it becomes a starting point of grain boundary fracture. Therefore, by using high-purity copper constituting the insulating substrate, the tensile strength and elongation of the copper plate are improved while the crystal grains are appropriately refined, thereby increasing the resistance to the load caused by deformation due to thermal expansion, preventing intergranular breakage, and bonding properties. improvement can be expected.

For example, in Patent Document 1, a pure copper plate used for a heat dissipation substrate is made of pure copper with a purity of 99.90 mass% or more, and a pure copper plate with a specific ratio of X-ray diffraction intensity is disclosed. Oxygen-free copper which comprises a pure copper plate WHEREIN: The etching property of a pure copper plate improves by prescribing|regulating the ratio of the crystal grain diameter of 100 micrometers or less, and X-ray-diffraction intensity.

In addition, Patent Document 2 discloses a copper alloy plate suitable for heat dissipation electronic components and large current electronic components, the copper alloy sheet having a tensile strength of 350 MPa or more and controlling the degree of integration of the crystal orientation at a predetermined position. By controlling the degree of integration of the crystal orientation of a predetermined position, the repetitive bending workability of a copper alloy plate, etc. improve.

Patent Document 1: Japanese Patent Application Laid-Open No. 2014-189817 Patent Document 2: Patent No. 5,475,914 Publication

However, since the pure copper plate disclosed in Patent Document 1 is difficult to generate irregularities on the surface by etching, it has excellent adhesion to other members, but bonding to other members at high temperature is not studied at all. In addition, although the copper alloy plate disclosed in patent document 2 is examining heat resistance, only the heat resistance by heat processing at 200 degreeC for 30 minute(s) was considered. Moreover, the copper alloy plate disclosed in patent document 2 has a tensile strength of 350 MPa or more, and does not correspond to the range of 150-330 MPa suitable as a copper plate material used for an insulated substrate. In addition, in both patent documents 1 and 2, no mention is made about the defect after bonding a copper plate to an insulated substrate. Therefore, when the semiconductor element heats up, deformation of the insulating substrate caused by the difference in thermal expansion coefficient between the copper plate material and the ceramic substrate, the problem of separation of the ceramic substrate and the copper plate, Problems of inhomogeneity and lowering of bonding properties are still unresolved.

In view of the above circumstances, it is an object of the present invention to provide an insulating substrate having a copper plate material having excellent heat resistance and fine crystal grains, and a method for manufacturing the same.

[1] An insulating substrate in which a ceramic substrate, a first copper plate formed on one surface of the ceramic substrate, and a second copper plate formed on the other surface of the ceramic substrate are bonded;

The first and second copper plate materials have a composition in which the total content of metal components selected from Al, Be, Cd, Mg, Pb, Ni, P, Sn and Cr is 0.1 to 2.0 ppm, and the copper content is 99.96 mass% or more. , In addition, when the crystal orientation distribution function obtained through the texture analysis by EBSD of the surfaces of the first and second copper plate materials is expressed as Euler angles (φ1, Φ, φ2), φ1 = 75° to 90°, Φ = The average value of the azimuth density in the range of 20° to 40°, φ2 = 35° is 0.1 or more and less than 15.0, and the orientation in the range of φ1 = 20° to 40°, Φ = 55° to 75°, and φ2 = 20° It has a rolled texture having an average density of 0.1 or more and less than 15.0, and

The insulated substrate of which the average grain size of the said 1st and 2nd copper plate material is 50 micrometers or more and 400 micrometers or less.

[2] The method of [1],

An average grain size of the first and second copper plates is greater than 100 µm and less than or equal to 400 µm, an insulating substrate.

[3] The method of [1] or [2],

The said ceramic substrate is an insulating substrate formed using the ceramic material containing at least 1 sort(s) of aluminum nitride, silicon nitride, alumina, and the compound of alumina and zirconia.

[4] The method according to any one of [1] to [3],

The first and second copper plate materials have a tensile strength of 210 MPa or more and 250 MPa or less, insulated substrate.

[5] The method according to any one of [1] to [4],

Elongation of the first and second copper plate materials is 25% or more and less than 50%, the insulating substrate.

[6] The method according to any one of [1] to [5],

The insulated substrate, wherein the conductivity of the first and second copper plate material is 95% IACS or more.

[7] In the method for manufacturing an insulating substrate according to any one of [1] to [6],

With respect to the 1st to-be-rolled material which is the material of the said 1st copper plate material, and the 2nd to-be-rolled material which is the material of the said 2nd copper plate material, the temperature increase rate of 10 degreeC/sec - 50 degreeC/sec, the attained temperature 250 degreeC - 600 degreeC, holding time An annealing process of performing annealing treatment under the conditions of 10 seconds to 3,600 seconds and a cooling rate of 10 ° C./sec to 50 ° C./sec;

After the annealing process, a cold rolling process of performing cold rolling in which the total working ratio of the first rolled material and the second to-be-rolled material is 10 to 65%;

After the cold rolling process, the first to-be-rolled material is bonded to one side of the ceramic substrate and the second to-be-rolled material is bonded to the other side of the ceramic substrate with a brazing material, respectively, and the first copper plate material and the second A bonding process of forming an insulating substrate to which copper plate materials are respectively bonded;

The bonding step includes a first heat treatment in which heat treatment is performed under the conditions of a temperature increase rate of 10° C./sec. to 100° C./sec., an attained temperature of 400° C. to 600° C., and a holding time of 10 seconds to 300 seconds, and a temperature increase rate of 10° C./sec. The manufacturing method of the insulated substrate comprised with the 2nd heat processing which heat-processes under the conditions of 100 degreeC/sec, 750 degreeC - 850 degreeC reached, and holding time 100 second - 7,200 second.

According to the present invention, in an insulating substrate in which a ceramic substrate, a first copper plate formed on one surface of the ceramic substrate, and a second copper plate formed on the other surface of the ceramic substrate are bonded, the first and second copper plates include Al, Be, Cd, Mg, Pb, Ni, P, Sn and Cr has a composition in which the total content of the metal components selected from 0.1 to 2.0 ppm and the copper content is 99.96 mass% or more, and the first and second copper When the crystal orientation distribution function obtained through the texture analysis by EBSD of the plate surface is expressed as Euler angles (φ1 , Φ, φ2), φ1 = 75°~ 90°, Φ = 20°~ 40°, φ2 = 35° A rolled set having an average value of azimuth density in the range of 0.1 or more and less than 15.0, φ1 = 20° to 40°, Φ = 55° to 75°, and φ2 = 20° average value of orientation density in the range of 0.1 or more and less than 15.0 It has a structure, and when the average crystal grain diameters of the said 1st and 2nd copper plate materials are 50 micrometers or more and 400 micrometers or less, the insulation board|substrate excellent in heat resistance characteristic can be obtained.

Further, according to the present invention, since the first and second copper plate materials exhibit excellent heat resistance characteristics, the load stress of the entire insulating substrate is reduced, and the resistance to the load due to thermal expansion is increased. Accordingly, it is possible to suppress the deformation of the insulating substrate caused by the difference in the coefficient of thermal expansion between the first and second copper plates and the ceramic substrate, and furthermore, it is possible to reduce the separation of the ceramic substrate and the first and second copper plates, that is, decrease the bonding property. can be suppressed

1 is a crystal orientation distribution diagram showing an example of the result of measuring the rolled texture of the surface of the copper plate material used for the insulating substrate of the present invention by EBSD and analysis by ODF. Fig. 1(A) is a crystal orientation distribution diagram of φ2 = 20°, and Fig. 1(B) is a crystal orientation distribution diagram of φ2 = 35°.

Hereinafter, details and embodiments of the insulating substrate of the present invention will be described. In addition, the numerical range expressed using “ ~ ” below means a range including the numerical values before and after “ ~ ” as the lower limit and upper limit.

<Insulation substrate>

In the insulating substrate of the present invention, a ceramic substrate, a first copper plate formed on one surface of the ceramic substrate, and a second copper plate formed on the other surface of the ceramic substrate are joined. That is, the insulating substrate has a laminate structure in which a ceramic substrate is disposed between a first copper plate and a second copper plate, and the first copper plate, the ceramic substrate, and the second copper plate are rolled and bonded in this order, respectively. The first copper plate material and the ceramic substrate, and the ceramic substrate and the second copper plate material may have a layer structure bonded to each other. The first copper plate and the ceramic substrate, and the ceramic substrate and the second copper plate may be joined by, for example, a brazing material, an adhesive, soldering, etc., and among them, joining via a brazing material is preferable. In addition, the thickness of the insulating substrate can be appropriately selected depending on the use situation, for example, it is preferably 0.3 mm to 10.0 mm, more preferably 0.8 mm to 5.0 mm. In addition, unless otherwise specified, for convenience, the first grade copper plate and the second copper plate may be simply referred to as 'copper plate' in the following.

[Ceramic Substrate]

The ceramic substrate used for the insulating substrate of this invention will not specifically limit, if it is formed from the ceramic material with high insulation. Such a ceramic substrate is preferably formed using, for example, aluminum nitride, silicon nitride, alumina, and a ceramic material mainly composed of at least one of an alumina and a zirconia compound. The thickness of the ceramic substrate is not particularly limited, but, for example, is preferably 0.05 mm to 2.0 mm, and more preferably 0.2 mm to 1.0 mm.

[Copper plate]

In general, a copper plate material refers to a material in which a copper material (before processing and having a predetermined composition) is processed into a predetermined shape (eg, plate, strip, foil, rod, wire, etc.). Among them, “plate material” refers to a material that has a specific thickness, is stable in shape, and is diffused in the plane direction, and includes a strip-shaped material in a broad sense. In the present invention, a 'copper plate' means a corresponding 'plate' formed of copper having a predetermined composition.

[Component composition of copper plate material]

For the insulating substrate of the present invention, a copper plate material having a copper content of 99.96 mass% or more, preferably a copper plate material of 99.99 mass% or more is used. When copper content is less than 99.96 mass %, thermal conductivity falls and desired heat dissipation cannot be acquired. In addition, in the copper plate material, the total content of a metal component selected from Al, Be, Cd, Mg, Pb, Ni, P, Sn and Cr is 0.1 ppm to 2.0 ppm. Although it does not specifically limit about the lower limit of the total content of these metal components, In consideration of unavoidable impurities, it was set to 0.1 ppm. On the other hand, when the total content of these metal components exceeds 2.0 ppm, the desired orientation density cannot be obtained. Therefore, the effect of increasing the resistance to the load due to thermal expansion applied to the insulating substrate cannot be obtained, so that the insulating substrate is deformed or the ceramic substrate and the copper plate are peeled off. In addition, in addition to copper and a metal component selected from Al, Be, Cd, Mg, Pb, Ni, P, Sn, and Cr, the copper plate material may contain unavoidable impurities as the remainder. The unavoidable impurity means an impurity at a content level that may be unavoidably included in the manufacturing process. The component composition of the first copper sheet and the component composition of the second copper sheet may be the same or different, but they are preferably the same from the viewpoint of manufacturing efficiency.

GDMS method can be used for quantitative analysis of the said metal component of a copper plate material. GDMS method is an abbreviation of Glow Discharge Mass Spectrometry. Using a solid sample as a cathode, sputtering the sample surface using glow discharge, and ionizing the emitted neutral particles by colliding with Ar or electrons inside the plasma. It is a technology to analyze the ratio of trace elements contained in metals by measuring

[Rolled aggregate organization]

The copper plate material used for the insulating substrate of the present invention represents a crystal orientation distribution function (ODF) obtained through texture analysis by EBSD of the surface of the copper plate material as Euler angles (φ1, Φ, φ2). When φ1 = 75° to 90°, φ = 20° to 40°, and φ2 = 35°, the average value of the azimuth density is 0.1 or more and less than 15.0, and φ1 = 20° to 40°, Φ = 55 The average values of the orientation densities in the range of ° to 75 ° and phi 2 = 20 ° have a rolling texture of 0.1 or more and less than 15.0. Euler angles (φ1, Φ, φ2) are the RD direction for the rolling direction, the direction perpendicular to the RD direction (plate width direction) as the TD direction, and the direction perpendicular to the rolling surface (RD surface) as the ND direction, RD The azimuth rotation with the direction as the axis is expressed as φ, the azimuth rotation with the ND direction as the axis is expressed as ϕ1, and the azimuth rotation with the TD direction as the axis is expressed as ϕ2. Orientation density is a parameter used to quantitatively analyze the abundance ratio and dispersion state of crystal orientations in a texture, and by performing EBSD and X-ray diffraction, three or more types of (100), (110), (112), etc. Based on the measurement data of positive pole viscosity, it is calculated by the crystal orientation distribution analysis method by the series expansion method. In the crystal orientation distribution diagram in which phi 2 obtained through texture analysis by EBSD is fixed at a predetermined angle, the orientation density distribution within the RD plane is displayed. Although the rolled texture which the 1st copper plate material has and the rolled texture which the 2nd copper plate material has may be same or different, it is good that they are the same from a viewpoint of manufacturing efficiency.

EBSD method is an abbreviation of Electron BackScatter Diffraction, and is a crystal orientation analysis technique using reflected electrons generated when a sample is irradiated with an electron beam in a scanning electron microscope (SEM). In the analysis by EBSD, the measurement area and the scanning step may be determined according to the size of the grains of the sample. For analysis of crystal grains after measurement, for example, TSL's analysis software OIM Analysis (trade name) can be used. The information obtained through the analysis of grains by EBSD includes information up to a depth of several tens of nanometers at which an electron beam penetrates the sample. The measurement point in the thickness direction is preferably set in the vicinity of a position from the sample surface to 1/8 times to 1/2 times the plate thickness.

BRIEF DESCRIPTION OF THE DRAWINGS It is a crystal orientation distribution diagram which shows an example of the result of measuring the rolling texture of the surface of the copper material used for the insulating substrate of this invention by EBSD, and analyzing it by ODF. Fig. 1(A) is a crystal orientation distribution diagram of φ2 = 20°, and Fig. 1(B) is a crystal orientation distribution diagram of φ2 = 35°. In the crystal orientation distribution map, when a state in which the crystal orientation distribution is arbitrary is assumed to be an orientation density of 1, the number of times the crystal orientation distribution is accumulated is indicated by contour lines. In FIG. 1 , a white portion indicates a high azimuth density, a black portion indicates a low azimuth density, and portions other than that indicate a higher azimuth density as it is closer to white. In the present invention, the average value of the azimuth density of the region enclosed by the dotted line in FIG. ) has a rolled texture having an average value of azimuthal density of less than 15 in the area enclosed by the dotted line (φ1 = 75° to 90°, Φ = 20° to 40°, φ2 = 35°). In Fig. 1(A), the average value of the former azimuth density is 8, and in Fig. 1(B) , the crystal orientation distribution diagram in which the average value of the latter azimuth density is 4 is shown.

The copper plate material used for the insulating substrate in the present invention has an orientation in the range of φ1 = 75° to 90°, Φ = 20° to 40°, and φ2 = 35° in the crystal orientation distribution function obtained through texture analysis by EBSD. The average value of the density is 0.1 or more and less than 15.0, and the average value of the orientation density in the range of φ1 = 20 ° to 40 °, Φ = 55 ° to 75 °, and φ2 = 20 ° is 0 0.1 or more and less than 15.0 Rolled texture have As such, by appropriately controlling the orientation density, the copper plate material exhibits excellent heat resistance properties by suppressing the growth of crystal grains during heat treatment at high temperatures (eg, 700° C. or higher). When the average value of the orientation density in the range of φ1 = 75° to 90°, Φ = 20° to 40°, and φ2 = 35° is 15.0 or more, the crystal orientation cannot be sufficiently controlled, so the ), the growth of crystal grains cannot be suppressed during heat treatment, resulting in poor heat resistance. Accordingly, resistance to a load due to thermal expansion applied to the insulating substrate increases, and thus the insulating substrate may be deformed or the ceramic substrate and the copper plate may be peeled off. In addition, even when the average value of the orientation density in the ranges of φ1 = 20° to 40°, Φ = 55° to 75°, and φ2 = 20° is 15.0 or more, similarly, the crystal orientation cannot be sufficiently controlled, so that the heat resistance property is deteriorated. do. Accordingly, resistance to a load due to thermal expansion applied to the insulating substrate increases, and thus the insulating substrate may be deformed or the ceramic substrate and the copper plate may be peeled off. Incidentally, average value of azimuth density in the range of φ1 = 75° to 90°, Φ = 20° to 40°, φ2 = 35°, φ1 = 20° to 40°, Φ = 55° to 75°, φ2 = 20° The lower limit of each of the average values of the azimuth density in the range of 0.1 was defined as the minimum value of the azimuth density that could be analyzed by the texture analysis by EBSD.

[Average grain size]

The average crystal grain size of the copper plate material used for the insulating substrate of this invention is 50 micrometers or more and 400 micrometers or less, and it is larger than 100 micrometers, and it is preferable that they are 400 micrometers or less. If the average grain size is less than 50 µm, the crystal orientation cannot be sufficiently controlled, and the heat resistance properties are deteriorated. On the other hand, when the average grain size exceeds 400 μm, sufficient tensile strength and elongation cannot be obtained, and the resistance to the load due to thermal expansion applied to the insulating substrate increases, and the insulating substrate is deformed or the ceramic substrate and the copper plate are peeled off. occurs Moreover, in the interface between a copper plate material and a ceramic substrate, a defect (void) is easy to generate|occur|produce in the part where the crystal grain boundary of a copper plate material contact|connects the interface. When the average grain size is 100 μm or less, the grain boundary of the copper plate material in contact with the ceramic substrate increases remarkably, and there is a possibility that the bonding strength may be lowered. Therefore, it is preferable that the average grain size is larger than 100 nm. In addition, the average grain size can be measured through EBSD analysis on the RD surface of the copper plate material. For example, the average grain size of the entire grain size in the measurement range can be defined as the average grain size. In addition, although the average grain size of a 1st copper plate material and the average grain diameter of a 2nd copper plate material may be same or different, it is good that they are the same from a viewpoint of manufacturing efficiency.

[thickness of plate]

The thickness (thickness of the plate) of the first copper plate material and the second copper plate material is not particularly limited, but is preferably 0.05 mm to 7.0 mm, more preferably 0.1 mm to 4.0 mm. The thickness of the first copper plate and the thickness of the second copper plate may be the same or different, but if the volumes of each copper plate are significantly different in the bonding heat treatment and heat cycle test, the plate may be warped due to the difference in the amount of thermal expansion. Therefore, according to the circuit design of the insulated substrate, it is desirable to properly match the thickness of each plate.

[characteristic]

(The tensile strength)

It is preferable that the tensile strength of a copper plate material is 210 Mpa or more and 250 Mpa or less. If the tensile strength is less than 210 MPa, the strength currently required is not sufficient. On the other hand, when the tensile strength exceeds 250 MPa, the elongation and workability tend to decrease.

(elongation)

It is preferable that the elongation of a copper plate material is 25 % or more and less than 50 %. When the elongation is less than 25%, there is a fear that the insulating substrate may be deformed or the ceramic substrate and the copper plate may be peeled off with respect to the load stress due to thermal expansion applied to the insulating substrate. On the other hand, when the elongation exceeds 50%, the strength tends to be insufficient.

It is preferable that the electrical conductivity of a copper plate material is 95% IACS or more. When the conductivity is less than 95%, the thermal conductivity becomes low, and there is a tendency that excellent heat dissipation properties cannot be obtained.

Next, an example of the manufacturing method of the insulated substrate which concerns on this invention is demonstrated.

[Method for manufacturing insulated substrate]

The manufacturing method of the insulated substrate which concerns on this invention includes an annealing process [process A], a cold rolling process [process B], and a bonding process [process C]. When the treatment in these steps is performed in this order, the insulating substrate according to the present invention in which the first copper plate material, the ceramic substrate, and the second copper plate material are joined can be obtained.

First, in the annealing step [Step A], the rolled material manufactured from the copper material having the above component composition, that is, the first rolled material that is the material of the first copper plate, and the second rolled material that is the material of the second copper plate, Annealing is performed under the conditions of a temperature increase rate of 10°C/sec to 50°C/sec, a reached temperature of 250°C to 600°C, a holding time of 10 seconds to 3,600 seconds, and a cooling rate of 10°C/sec to 50°C/sec. In the annealing step [Step A], if the annealing conditions are outside the above specified range, the average crystal grain size of the obtained copper sheet material is coarse and coarse, and the crystal orientation cannot be sufficiently controlled, and the heat resistance characteristics of the insulating substrate tend to be inferior. For example, if the reached temperature is too high or the temperature rise rate is too slow, the crystal orientation may not be sufficiently controlled, and the orientation density in the range of φ1 = 75° to 90°, Φ = 20° to 40°, and φ2 = 35°. tends to increase significantly. Moreover, since the distortion in an annealing process is not relieve|moderated when the reached temperature is too low, the distortion before joining heat processing following cold rolling also becomes large. For this reason, recrystallization is accelerated|stimulated even if a rolled texture is within a prescribed range, and there exists a possibility that a crystal grain may become coarse and coarse.

In the cold rolling process [Process B], after the annealing process ([Process A]), the total working ratio of the first to-be-rolled material, which is the material of the first copper plate, and the second to-be-rolled, which is the material of the second copper plate, is 10 to 65%. phosphorus cold rolling is carried out. In the cold rolling process [Process B], if the cold rolling conditions are outside the above specified range, the average grain size of the copper sheet material obtained is coarse and coarse, and the crystal orientation cannot be sufficiently controlled, and the heat resistance properties of the insulating substrate tend to be inferior. . For example, when the total machining rate is remarkably high, the crystal orientation cannot be sufficiently controlled, so that the average value of the orientation density in the ranges of φ1 = 20° to 40°, Φ = 55° to 75°, and φ2 = 20° tends to increase significantly. On the other hand, when the total processing rate is too low, the growth of crystal grains cannot be suppressed, and there is a risk that the crystal grains become coarse and coarse.

In the bonding step [Step C], after the cold rolling step ([Step B]), a first to-be-rolled material, which is a material of a first copper plate, is applied to one side of the ceramic substrate, and a material of a second copper sheet is applied to the other side of the ceramic substrate. The phosphorus second to-be-rolled material is respectively joined via a brazing material such as Ag-Cu-Ti-based material to form an insulating substrate to which the first copper plate material and the second copper plate material are respectively joined. The bonding step [Step C] includes a first heat treatment in which heat treatment is performed under the conditions of a temperature increase rate of 10°C/sec to 100°C/sec, an attainable temperature of 400°C to 600°C, and a holding time of 10 seconds to 300 seconds, and a temperature increase rate of 10°C It consists of the 2nd heat processing which heat-processes under the conditions of /sec - 100 degreeC/sec, reached temperature 750 degreeC - 850 degreeC, and holding time of 100 second - 7,200 second. In the bonding process [Step C], if the bonding conditions are outside the range of the above regulations, the average grain size of the obtained copper sheet material becomes coarse, coarse, or excessively fine, the crystal orientation cannot be sufficiently controlled, and the heat resistance properties of the insulating substrate are deteriorated tends to For example, if the temperature increase rate of the first heat treatment and the second heat treatment is too fast, the crystal orientation cannot be sufficiently controlled, and φ1 = 75° to 90°, φ = 20° to 40°, and φ2 = 35°. The average value of the azimuth density in . On the other hand, when the attained temperature of 1st heat processing is too low, the distortion by cold rolling will not relieve|moderate the rolling texture even if it exists in a prescribed range. For this reason, in the second heat treatment, recrystallization is promoted by distortion, and there is a possibility that the grains become coarse and coarse. Moreover, when the attained temperature of 2nd heat processing is too high, there exists a possibility that the growth of a crystal grain cannot be suppressed and a crystal grain may become coarse and coarse. On the other hand, when the reached temperature of the second heat treatment is too low, the interface between the copper plate material and the ceramic substrate is not activated and it is difficult to bond them well.

[Manufacturing method of rolled material]

In the method for manufacturing an insulating substrate according to the present invention, the first and second materials to be rolled used in the annealing process [Step A] are not particularly limited as long as they are made of a copper material having the above component composition. Such a to-be-rolled material can be manufactured through the following process, for example. An example of a method of manufacturing a material to be rolled that can be used in the annealing process [process A] of the insulating substrate according to the present invention will be described below.

The copper plate material before bonding to the ceramic substrate constituting the insulating substrate of the present invention, that is, the first rolled material serving as the first copper plate material and the second rolled material serving as the second copper plate material (hereinafter, the first rolled material and the second to be pressed material) As a manufacturing method of a soft material (sometimes simply referred to as a 'rolled material'), for example, a melting and casting process [process 1], a homogenization heat treatment process [process 2], a hot rolling process [process 3], a cooling process [process 4 ], chamfering process [process 5], first cold rolling process [process 6], first annealing process [process 7], second cold rolling process [process 8], second annealing process [process 9], finish rolling process The treatment consisting of [Step 10], the final annealing step [Step 11], and the surface oxide film removal step [Step 12] are sequentially performed.

First, in the melting and casting step [Step 1], a copper material is melted and cast to obtain an ingot. The copper material has a composition in which the total content of metal components selected from Al, Be, Cd, Mg, Pb, Ni, P, Sn and Cr is 0.1 to 2.0 ppm, and the copper content is 99.96 mass% or more. In the homogenization heat treatment step [Step 2], the obtained ingot is subjected to a homogenization heat treatment at a holding temperature of 700 to 1,000° C. and a holding time of 10 minutes to 20 hours. In a hot rolling process [process 3], it hot-rolls so that a total working rate may become 10-90%. In the cooling step [Step 4], it is rapidly cooled at a cooling rate of 10°C/sec or more. In the chamfering process [process 5], the both sides of the cooled material are chamfered by about 1.0 mm each. Through this, the oxide film on the surface of the obtained plate is removed.

In the first cold rolling step [Step 6], cold rolling is performed several times so that the total working ratio is 75% or more.

In the first annealing step [Step 7], heat treatment is performed under the conditions of a temperature increase rate of 1 to 100°C/sec, an attainable temperature of 100 to 500°C, a holding time of 1 to 900 seconds, and a cooling rate of 1 to 50°C/sec.

In a 2nd cold rolling process [process 8], it cold-rolls so that a total working rate may be set to 60 to 95%.

In the second annealing step [Step 9], heat treatment is performed under the conditions of a temperature increase rate of 10 to 100°C/sec, an attained temperature of 200 to 550°C, a holding time of 10 seconds to 3,600 seconds, and a cooling rate of 10 to 100°C/sec. .

In the finish rolling step [Step 10], cold rolling is performed so that the total working ratio is 10 to 60%. In the final annealing step [Step 11], heat treatment is performed under the condition that the reached temperature is 125 to 400°C. In the surface oxide film removal step [Step 12], pickling and polishing are performed for the purpose of removing the oxide film on the surface of the obtained plate and cleaning the surface. In addition, the working ratio R (%) in the rolling process is defined by the following formula. In this way, the to-be-rolled material used as the raw material of a copper plate material can be manufactured.

R = (t ₀ -t)/t ₀ ×100

In the formula, t0 is the plate thickness before rolling, and t is the plate thickness after rolling.

Example

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.

(Examples 1 to 11 and Comparative Examples 1 to 17)

First, as shown in Table 1, two to-be-rolled materials (test materials) having a thickness of 1.0 mm having a predetermined component composition were prepared, and each was set as a first rolled material and a second to-be-rolled material. In addition, as a ceramic material, the 0.5 mm-thick ceramic substrate formed using silicon nitride was used.

Next, each to-be-rolled material produced from the top used as a copper plate material was annealed under the conditions shown in Table 2 [process A]. Cold rolling was performed for each to-be-rolled material obtained after the annealing treatment at the total working ratios shown in Table 2 (that is, the working ratio of all 1st to-be-rolled material and 2nd to-be-rolled material) [Step B]. For each material to be rolled obtained after cold rolling, a first rolled material corresponding to a first copper plate is applied to one side of the ceramic substrate, and a second to-be-rolled material corresponding to a second copper plate is applied to the other surface of the ceramic substrate, Ag-Cu-Ti. Each of the brazing materials was used and joined to prepare an insulating substrate in which the first copper plate material and the second copper plate material were respectively joined [Step C]. In [Step C], heat treatment was performed under the first heat treatment and second heat treatment conditions shown in Table 2. The insulating substrate used as a sample was produced through the above process.

<Measuring method and evaluation method>

[Quantitative analysis of copper plate material]

GDMS method was used for quantitative analysis of each produced copper plate material. In each Example and each comparative example, analysis was performed using VG-9000 manufactured by V.G.Scientific. Table 1 shows the content (ppm) and Cu content (mass%) of Al, Be, Cd, Mg, Pb, Ni, P, Sn, and Cr contained in each copper plate material. In addition, each copper plate may contain unavoidable impurities. A blank in Table 1 means that the corresponding metal component was 0 ppm. In addition, when the measured value by GDMS method was less than 0.1 ppm, content of a metal component was made into 0 ppm.

<Orientation Density of Copper Plate>

The EBSD method was used for the orientation density analysis of the rolled texture of each copper plate material from each insulating board|substrate which is a sample. At the time of EBSD measurement of each Example and each comparative example, the measurement sample plane containing 200 or more crystal grains was measured. The measurement area and scan step of the measurement sample surface were determined according to the grain size of the specimen. After measurement, analysis software OIM Analysis (trade name) of TSL was used to analyze the grains. The information obtained through the analysis of grains by EBSD includes information up to a depth of several tens of nanometers where the electron beam penetrates the specimen. In addition, the measurement location of the plate|board thickness direction was set to the position vicinity of 1/8 times - 1/2 times of plate|board thickness (t) from the test material surface.

[Average grain size of copper plate]

The average crystal grain size of each copper plate material from each insulated substrate which is a sample measured the measurement sample surface containing 200 or more crystal grains in the EBSD measurement of a rolling surface. When analyzing the measurement results, the average grain size was calculated from all grains within the measurement range. The analysis software OIM Analysis (trade name) of TSL was used for the analysis of the crystal grain size. The information obtained through the analysis of grains by EBSD includes information up to a depth of several tens of nanometers where the electron beam penetrates the specimen. In addition, the measurement location of the plate|board thickness direction was set to the position vicinity of 1/8 times - 1/2 times of plate|board thickness (t) from the test material surface. When the average crystal grain size was in the range of 50 µm or more and 400 µm or less, it was evaluated that the crystal grains were finely refined.

[Conductivity (EC) of copper plate material]

The conductivity of each copper plate peeled off from each insulating substrate serving as a sample was measured using a sigma tester (IACS% measurement using overcurrent). A case in which the conductivity of each copper plate was 95% IACS or higher was evaluated as 'good', and a case below 95% IACS was evaluated as 'poor'.

[Tensile strength of copper plate]

The copper plate material was peeled from each insulated board|substrate which is a sample, and the cut out test piece was measured according to JIS Z2241, and the average value was shown. The case where the tensile strength of the copper plate material was 210 MPa or more was evaluated as 'good', and the case where the tensile strength of the copper plate material was less than 210 MPa was evaluated as 'poor'.

[Elongation of copper plate]

When measuring tensile strength, it was measured according to JIS Z2241, and the average value was shown. The case where the elongation of the copper plate material was 25% or more was evaluated as 'good', and the case where the elongation was less than 25% was evaluated as 'poor'.

[Heat resistance properties of insulated substrates]

The heat cycle test in which the sample of each insulated substrate is processed for 1200 cycles under the conditions of -40 degreeC - 250 degreeC (1 cycle -40 degreeC: 30-minute hold|maintenance/250 degreeC: 30-minute hold|maintenance) was implemented. After the heat cycle test, it was visually observed whether cracks occurred in the ceramic substrate. The case where cracks did not occur was evaluated as '○', and the case where cracks occurred was evaluated as 'x'.

In Table 3, the result of the orientation density of a copper plate material, an average grain size, electrical conductivity, tensile strength, elongation, and the heat resistance characteristic of an insulated substrate is shown.

As shown in Tables 1 to 3, in Examples 1 to 11, the manufacturing conditions of the insulating substrate, the component composition of the copper plate constituting the insulating substrate, the orientation density, and the average grain size were all within the appropriate range, so that the heat resistance characteristics were excellent. An insulated substrate was obtained. In particular, in Examples 1-5 and 7-11, all of the electrical conductivity, tensile strength, and elongation rate of the copper plate material with which an insulated substrate were equipped were favorable. Incidentally, although not shown in Table 2, in Example 5, the average grain size was smaller than 100 µm, and a tendency was observed in which the bonding strength was lower than in the other examples.

On the other hand, in Comparative Examples 1 to 17, one or both of the manufacturing conditions of the insulating substrate and the component composition of the copper plate material constituting the insulating substrate are outside the appropriate range, so that all or one of the orientation density and the average grain size are outside the appropriate range. , and further cracks occurred in the heat cycle test of the insulated substrate.

As such, the insulating substrate of the present invention formed using a copper plate material whose component composition, orientation density, and average grain size are strictly controlled exhibits excellent heat resistance properties, so that the load stress of the entire insulating substrate is reduced, resistance is increased. Through this, deformation of the insulating substrate caused by the difference in the coefficient of thermal expansion between the copper plate material and the ceramic substrate is suppressed, and further, it is possible to suppress the separation of the ceramic substrate and the copper plate material, that is, deterioration in bonding properties.

Claims (7)

An insulating substrate in which a ceramic substrate, a first copper plate formed on one surface of the ceramic substrate, and a second copper plate formed on the other surface of the ceramic substrate are joined together,
The first and second copper plate materials have a composition in which the total content of metal components selected from Al, Be, Cd, Mg, Pb, Ni, P, Sn and Cr is 0.1 to 2.0 ppm, and the copper content is 99.96 mass% or more. , In addition, when the crystal orientation distribution function obtained through the texture analysis by EBSD of the surfaces of the first and second copper plate materials is expressed as Euler angles (φ1, Φ, φ2), φ1 = 75° to 90°, Φ = The average value of the azimuth density in the range of 20° to 40°, φ2 = 35° is 0.1 or more and less than 15.0, and the orientation in the range of φ1 = 20° to 40°, Φ = 55° to 75°, and φ2 = 20° It has a rolled texture having an average density of 0.1 or more and less than 15.0, and
An average grain size of the first and second copper plate materials is 50 µm or more and 400 µm or less, Insulated substrate. The method according to claim 1,
An average grain size of the first and second copper plate materials is greater than 100 µm and less than or equal to 400 µm, the insulating substrate. 3. The method according to claim 1 or 2,
The said ceramic substrate is an insulating substrate formed using the ceramic material containing at least 1 sort(s) of aluminum nitride, silicon nitride, alumina, and the compound of alumina and zirconia. 3. The method according to claim 1 or 2,
The first and second copper plate members have tensile strengths of 210 MPa or more and 250 MPa or less, insulated substrate. 3. The method according to claim 1 or 2,
Elongation of the first and second copper plate materials is 25% or more and less than 50%, the insulating substrate. 3. The method according to claim 1 or 2,
The insulated substrate, wherein the conductivity of the first and second copper plate material is 95% IACS or more. In the manufacturing method of the insulated substrate of Claim 1 or 2,
With respect to the 1st to-be-rolled material which is the material of the said 1st copper plate material, and the 2nd to-be-rolled material which is the material of the said 2nd copper plate material, the temperature increase rate 10 degreeC/sec - 50 degreeC/sec, the reached temperature 250 degreeC - 600 degreeC, holding time An annealing step of performing annealing treatment under the conditions of 10 seconds to 3,600 seconds, a cooling rate of 10 ° C./sec to 50 ° C./sec;
After the annealing process, a cold rolling process of performing cold rolling in which the total working ratio of the first rolled material and the second to-be-rolled material is 10 to 65%;
After the cold rolling process, the first to-be-rolled material is bonded to one side of the ceramic substrate and the second to-be-rolled material is bonded to the other side of the ceramic substrate with a brazing material, respectively, and the first copper plate material and a bonding process of forming an insulating substrate to which the second copper plate materials are respectively bonded,
The bonding step includes a first heat treatment in which heat treatment is performed under the conditions of a temperature increase rate of 10° C./sec to 100° C./sec, an ultimate temperature of 400° C. to 600° C., and a holding time of 10 seconds to 300 seconds, and a temperature increase rate of 10° C./sec to The manufacturing method of the insulated substrate comprised with the 2nd heat processing which heat-processes under the conditions of 100 degreeC/sec, attaining temperature 750 degreeC - 850 degreeC, and holding time 100 second - 7,200 second.

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