JP6719316B2 - Copper alloy plate material for heat dissipation member and manufacturing method thereof - Google Patents

Description

The present invention relates to a copper alloy plate and a method for manufacturing the same, and more particularly to a copper alloy plate suitable for a semiconductor and a heat dissipation member of an LED and a method for manufacturing the same.

Generally, a semiconductor or LED (hereinafter, semiconductor chip) and a copper alloy plate material for heat dissipation member are joined by soldering the semiconductor chip and the copper alloy plate material for heat dissipation member at a high temperature of 250° C. or higher. At this time, since the semiconductor chip, the solder, and the copper alloy plate material for the heat dissipation member have different thermal expansion coefficients, a large strain occurs in the entire module due to the difference in the thermal expansion coefficient when cooled to room temperature. Thermal expansion here means that the dimensions of a substance change with increasing temperature. The dimensional change is proportional to the coefficient of thermal expansion of each material. In semiconductor chips, for example, Si and copper alloy plate materials, the coefficient of thermal expansion of Cu is 16.6, whereas the coefficient of thermal expansion of Si is 2.6. During cooling, compressive stress is applied to the semiconductor chip and tensile stress is applied to the copper alloy plate material. At this time, since the solder having the highest thermal expansion coefficient is as thin as 1/10 or less of the thickness of the copper plate, the amount of shrinkage of the semiconductor chip and the copper alloy plate material during cooling cannot be absorbed, and a large load is applied to the entire module. .. When a high strain is applied to the semiconductor module, not only the dimensional change due to the deformation but also the semiconductor characteristic (change in band structure) is affected by the dimensional change. Therefore, there is a demand for a semiconductor module that does not easily change.

Therefore, it is expected that the load stress due to the dimensional change at the time of thermal expansion and contraction will be reduced by lowering the longitudinal elastic modulus of the copper alloy plate material for the heat dissipation member. When a material having a high longitudinal elastic modulus and a material having a low longitudinal elastic modulus are prepared and the same dimensional change is applied in the elastic deformation region, the material having a lower elastic modulus has a lower load stress.

According to the prior art, by controlling the (122) plane and the (133) plane in the metallographic structure, the bending deflection coefficient is enhanced and the spring characteristics are enhanced. However, the difference in the coefficient of thermal expansion during joining with a semiconductor chip and during cooling. The load stress has not been solved by.

For example, in Patent Document 1, by controlling the integrated diffraction intensity of the (111) plane and the integrated diffraction intensity of the (220) plane, the bending deflection coefficient in the vertical direction of rolling is increased, and the heat shrinkage rate of the heat dissipation plate material falls within an appropriate range. However, the load stress due to the difference in the coefficient of thermal expansion during bonding with the semiconductor chip and during cooling has not been solved. Further, since it is only one direction of the vertical direction of rolling, it cannot cope with isotropic thermal expansion and contraction of the semiconductor chip. Further, the deflection coefficient in the vertical direction of rolling is increased to 115 GPa or more, and when converted to Young's modulus, it is controlled to about 130 GPa or more.

Further, in Patent Document 2, the deflection coefficient is increased at an area ratio of 10° or less with TD (122) and a crystal orientation area ratio of 10% or more with an angle of 10° or less with TD (133). We have not solved the load stress due to the difference in the coefficient of thermal expansion during bonding with the semiconductor chip and during cooling. Further, since it is only one direction of the vertical direction of rolling, it cannot cope with isotropic thermal expansion and contraction of the semiconductor chip.

Patent No. 5453565 JP, 2005-990, A

In the present invention, in order to reduce the load stress of the entire semiconductor module caused by the difference in thermal expansion coefficient between the copper alloy plate material for heat dissipation member and the semiconductor chip, the longitudinal elastic modulus is continuously low from the rolling parallel direction to the vertical direction, It is another object of the present invention to provide a copper alloy sheet material for a heat dissipation member, which is excellent in strength and conductivity, and a method for producing the same.

The copper alloy plate material for heat dissipation members of the present invention contains 0 to 0.5 wt% of Sn, consists of the balance copper and unavoidable impurities, and has a crystal grain orientation distribution function (ODF: Crystal) when EBSD of the plate material surface is performed. Orientation Distribution Function), the azimuth density in the range of φ2=0°, φ=0°, φ1=0 to 90° is 3.0 or more and less than 40.0 on average.

INDUSTRIAL APPLICABILITY The present invention can provide a copper alloy sheet material for a heat dissipation member, which has a continuously low longitudinal elastic modulus from the rolling parallel direction to the vertical direction and is excellent in strength conductivity, and a manufacturing method thereof.

It is a typical crystal orientation distribution diagram of the copper alloy plate material which was measured by EBSD and obtained from ODF (orientation distribution function) analysis.

Hereinafter, embodiments of the copper alloy sheet material for heat dissipation members of the present invention will be described in detail.
One embodiment of the present invention is a copper alloy plate material for electric and electronic equipment, which contains Sn in an amount of 0 to 0.5 mass% and has a balance of Cu and inevitable impurities, and has a rolling texture. The rolling texture is obtained from the texture analysis by the EBSD method, and the Euler angle of a crystal grain orientation distribution function (ODF: crystal orientation distribution function), φ2=0°, φ=0 to 10°, φ1=0 to The copper alloy plate material for heat dissipation members has an average orientation density in the range of 90° of 3.0 or more and less than 40.

Here, the copper alloy plate material means a plate-shaped copper alloy material having a predetermined alloy composition before being processed. In particular, the plate material refers to a material having a specific thickness, stable in shape, and spreading in the surface direction, and broadly includes a strip material. In the present invention, the thickness of the plate material is not particularly limited, but is preferably 0.05 to 2.0 mm, more preferably 0.1 to 1.5 mm. The copper alloy sheet material of the present invention defines its characteristics by the atomic plane accumulation rate in a predetermined direction of the rolled sheet, but it is sufficient that the copper alloy sheet material has such characteristics. Therefore, the shape of the copper alloy plate is not limited to the plate or the strip. In the present invention, a pipe material is also interpreted and treated as a plate material.

The composition of the copper alloy sheet of the present invention and its action will be described. The copper alloy sheet material of the present invention may optionally contain Sn. When Sn is contained, it is contained at 0.05 to 0.5 mass %. By adding Sn, an ideal texture can be obtained depending on the state of solid solution and precipitation of Sn in the parent phase. If the Sn content is less than 0.05%, the formation of a texture is not promoted so much, and if it exceeds 0.5 mass%, the electrical conductivity decreases.

The copper alloy sheet material of the present invention may contain 0.3% in total of Ni, P, and O as optional additional elements in addition to the above Sn. By incorporating Ni and/or P together with Sn, it is possible to exert a synergistic effect in improving the stress relaxation resistance. However, if the total amount of Ni and P exceeds 0.3%, the conductivity is lowered, so the content is made 0.3% or less.

The copper alloy sheet material of the embodiment of the present invention has a rolling texture, and this rolling texture is an Euler of a crystal grain orientation distribution function (ODF: crystal orientation distribution function) obtained from a texture analysis by an EBSD method. The azimuth density in the range of angle, φ2=0°, Φ=0 to 10°, φ1=0 to 90° is 3.0 or more and less than 40 on average.

The EBSD method is an abbreviation for Electron BackScatter Diffraction, and is a crystal orientation analysis technique using backscattered electron Kikuchi line diffraction that occurs when a sample is irradiated with an electron beam in a scanning electron microscope (SEM). In the EBSD measurement in the present invention, a sample area of 800 μm×1600 μm containing 200 or more crystal grains was scanned and measured in 0.1 μm steps. The measurement area and the scan step may be determined according to the size of the crystal grain of the sample. For the analysis of the crystal grains after the measurement, an analysis Cevite OIM Analysis (trade name) manufactured by TSL was used. The information obtained in the analysis of crystal grains by EBSD includes information up to a depth of several tens nm where the electron beam penetrates the sample. Further, it is preferable that the measurement position in the plate thickness direction is near a position ⅛ to ½ times the plate thickness t from the sample surface.

The crystal orientation density is also represented by a crystal grain orientation distribution function (ODF: crystal orientation distribution function), which indicates a random crystal orientation distribution state of 1 and shows how many times the accumulation is performed. It is used when quantitatively analyzing the existing ratio of crystal orientations and the dispersed state of the texture. The azimuth density is a crystal orientation distribution analysis method by a series expansion method based on three or more kinds of positive electrode figure measurement data such as (100), (110), (112) positive point diagram from EBSD and X-ray diffraction measurement results. Is calculated by

FIG. 1 is a typical crystal orientation distribution diagram of a copper alloy sheet, which is measured by EBSD and obtained from ODF (orientation distribution function) analysis. In FIG. 1, it is shown by Euler angles in three directions of a direction RD parallel to the rolling direction and a plate width direction TD, which are directions orthogonal to the two axes in the rolling surface, and a normal direction ND of the rolling surface. That is, azimuth rotation of the RD axis is shown as Φ, azimuth rotation of the ND axis is shown as φ1, and azimuth rotation of the TD axis is shown as φ2. Each sectional view of FIG. 1 is a diagram in which the azimuth rotation φ2 of the TD axis of the ODF is divided at intervals of 5°, and the thick line frame indicates that in the sectional view of φ2=0°, φ=0 to 10°, φ1=0. The crystal orientation distribution is shown in the range from 90° to 90°.

At φ2=0°, the azimuth density in the range of φ=0 to 10° and φ1=0 to 90° is controlled to be 3.0 or more and less than 40 on average, so that 100 planes are continuously oriented in the vertical direction, and the longitudinal elastic modulus is lower than that of a randomly oriented material. As a result, the load stress generated due to the difference in the coefficient of thermal expansion during cooling of the heat dissipation board and the semiconductor after soldering can be reduced, and the characteristics of the semiconductor can be stabilized. When the azimuth density is less than 3.0, the longitudinal elastic modulus cannot be controlled to be low, and when a copper alloy plate material is used as a heat dissipation plate material, it is difficult to suppress the load due to the difference in coefficient of thermal expansion from the semiconductor chip. Becomes Further, when the orientation density is 40 or more, the strength of the plate material is lowered, and deformation is likely to occur when it is used as a heat dissipation substrate.

The copper alloy plate material for heat dissipation members of another embodiment of the present invention contains 0 to 0.5 mass% of Sn, and when EBSD of the plate material surface is performed, a crystal grain orientation distribution function (ODF: crystal orientation distribution function). The azimuth density in the range of φ2=0°, Φ=0 to 10°, φ1=0 to 90° is 5.0 or more and less than 40 on average, and the longitudinal elastic modulus of the rolling direction from 0° to 90° is It is a copper alloy plate material for heat dissipation members having an average value of 130 GPa or less. Here, the copper alloy plate material for heat dissipation members is controlled by controlling the longitudinal elastic modulus in the direction rotated at every 10° from the rolling parallel direction (RD) to the rolling vertical direction (TD) to 130 GPa or less. The load stress due to the difference in the coefficient of thermal expansion in the direction is reduced.

When the orientation density is less than 5.0, it tends to be somewhat difficult to control the longitudinal elastic modulus to be low. By controlling the orientation density to be less than 5.0 to 40, it becomes easy to control the average value of the longitudinal elastic modulus from 0° to 90° in the rolling direction to 130 GPa or less. The longitudinal elastic modulus of the copper alloy sheet according to the embodiment of the present invention may be 120 GPa or less, or 115 GPa or less. If the longitudinal elastic modulus exceeds 130 GPa, the non-stress tends to increase due to dimensional changes during thermal expansion and contraction.

The longitudinal elastic modulus was measured by rotating each test material in a direction RD parallel to the rolling direction, a plate width direction TD (a direction orthogonal to the rolling direction RD), and every 10° from RD to TD. In the same direction, test pieces of JIS Z2201-13B are processed, and measurement is performed according to JIS Z2241. For the tensile test, an autograph universal testing machine AG-10KTD manufactured by Shimadzu Corporation was used. Stress can be applied in the length direction of the test piece by a tensile tester to determine the proportional constant of strain and stress. The strain amount of 80% of the strain amount at yield is taken as the maximum displacement amount, the displacement amount is given by dividing the displacement amount into ten, and the proportional constant of strain and stress is obtained as the longitudinal elastic modulus from the measured values at the ten points. be able to.

The average crystal grain size of the copper alloy sheet according to the embodiment of the present invention may be 1 μm to 100 μm. If the average crystal grain size is less than 1 μm, the crystal orientation cannot be controlled and an elastic modulus of 130 GPa or less cannot be obtained. When the crystal grain size exceeds 100 μm, the tensile strength decreases.

It is a copper alloy plate material for heat dissipation members in which the tensile strength of the copper alloy plate material of one embodiment of the present invention is 300 MPa or more. When the tensile strength is less than 300 MPa, the member may be deformed when a load stress is applied due to a difference in coefficient of thermal expansion when used as a heat dissipation member. The tensile strength is controlled by adjusting the processing rate during rolling and the annealing temperature condition under the copper alloy substrate manufacturing conditions described below.

The copper alloy sheet material of the embodiment of the present invention is a copper alloy having the above alloy composition, is subjected to homogenizing heat treatment for performing homogenizing heat treatment on a material to be rolled obtained by rolling, and after the homogenizing heat treatment. Hot rolling the rolled material, cooling after the hot rolling, chamfering both sides of the rolled material after the cooling, and a total working rate of 75 after the chamfering. %, cold-rolling is performed so that the temperature rise rate is 10 to 100° C./second, the ultimate temperature is 100 to 400° C., the holding time is 1 to 900 seconds, and the cooling rate is 10 to 100° C./second. 1, annealing after the first annealing, cold rolling, heat treatment at a temperature rising rate of 10 to 200° C./second, an ultimate temperature of 300 to 800° C., a holding time of 10 to 3600 seconds, and cooling. It can be manufactured by performing a second annealing that cools at a rate of 10 to 200° C./second, and then performing finish rolling, low temperature annealing, pickling, and polishing.

Here, the total processing rate means the total of the rolling processing rates by multiple rollings, and the rolling processing rate is the value obtained by subtracting the sectional area after rolling from the sectional area before rolling by the sectional area before rolling. And multiplied by 100 and expressed as a percentage. That is, it is represented by the following formula.
[Rolling rate]={([cross-sectional area before rolling]-[cross-sectional area after rolling])/[cross-sectional area before rolling]}×100(%)

Moreover, you may hold|maintain homogenization heat processing at 800-1100 degreeC for 10 minutes-20 hours. The hot rolling may be performed at a total working rate of 10 to 90%, and after the hot rolling is finished, it may be rapidly cooled at a cooling rate of 10° C./sec or more. The oxide film on the surface of the hot rolled material is Alternatively, the surface may be removed by about 1.0 mm on one side. The cold rolling after chamfering may be performed by a plurality of rolling passes so that the total working rate becomes 75% or more. The first annealing is heat treatment in a continuous annealing furnace at a temperature rising rate of 10 to 100° C./second, an ultimate temperature of 100 to 400° C., a holding time of 1 second to 900 seconds, and then a cooling rate of 10 to 100° C./second. May be. The cold rolling after the first annealing may be performed so that the total working rate is 5 to 60%. In the second annealing, heat treatment may be performed at a temperature rising rate of 10 to 200° C./second, an ultimate temperature of 300 to 800° C., a holding time of 10 seconds to 3600 seconds, and cooling at a cooling rate of 10 to 200° C./second. The finish rolling may be performed by rolling so that the total working rate becomes 10 to 60%, and low-temperature annealing so that the ultimate temperature becomes 200 to 500°C. Furthermore, pickling and polishing are performed for the purpose of removing and cleaning the oxide film on the surface of the plate material.

Under the above manufacturing conditions, it is important to control the cold rolling and the first and second annealing steps after the surface cutting. That is, the rolling texture is sufficiently developed by setting the total working ratio of cold rolling to 75% or more, and the Euler angle of the crystal grain orientation distribution function (ODF) is increased by the first and second annealings. , Φ2=0°, Φ=0 to 10°, and φ1=0 to 90°, the azimuth density can be appropriately controlled. If the total processing rate is less than 75%, the orientation is randomized by the texture control by the first and second annealing, and the average orientation density tends to be less than 3.0. Further, when any one or more of the temperature rising rate, the reached temperature, the holding time and the cooling rate in the first and second annealing is out of the specified range, the orientation is randomized in the texture control, and the orientation The average density tends to be less than 3.0.

As described above, by appropriately controlling the conditions of each step in the above manufacturing method, the crystal grain orientation distribution function (ODF) obtained from the texture analysis of the rolled texture of the copper alloy sheet by the EBSD method. It is possible to control the Euler angle of the distribution function, the azimuth density in the range of φ2=0°, φ=0 to 10°, φ1=0 to 90°, to 3.0 or more and less than 40 on average. Further, this can reduce the longitudinal elastic modulus.

The present invention will be described in detail based on examples. The invention is not limited to these examples.
(Examples 1 to 10 and Comparative Examples 1 to 9)
A copper alloy material consisting of the balance copper and unavoidable impurities to which Sn is added so as to have the composition shown in Table 1 is melted in a high-frequency melting furnace, and this is cast and the ingot is rolled to form a copper alloy sheet material. Obtained. A homogenizing heat treatment step of performing a homogenizing heat treatment on the material to be rolled, a hot rolling step of performing a hot rolling on the material to be rolled after the homogenizing heat treatment step, and a cooling after the hot rolling step. A cooling step to be performed, a chamfering step of chamfering both surfaces of the material to be rolled after the cooling step, and a cold rolling at a working rate and a rolling pass number shown in Table 1 after the chamfering step, After the first annealing in which heat treatment is performed at the temperature increase rate, the ultimate temperature, the holding time, and the cooling rate shown, cold rolling is performed, and heat treatment is performed at the temperature increase rate, the ultimate temperature, the holding time, and the cooling rate shown in Table 1. After performing the second annealing, finish rolling, low temperature annealing, and pickling/polishing steps were performed to obtain test materials of Examples 1 to 10 and Comparative Examples 1 to 9.

With respect to the obtained test material, the average value of orientation density, average crystal grain size, average value of longitudinal elastic modulus, conductivity and tensile strength were measured by the following methods. The measured results are shown in Table 2.

(Crystal orientation density)
The abundance ratio of crystallographic orientations of the texture and the dispersion state are quantitatively analyzed by the crystal orientation density. From the EBSD and X-ray diffraction measurement results, it was calculated by the crystal orientation distribution analysis method by the series expansion method based on the measurement data of three or more types of positive electrode dot diagrams such as (100), (110), (112) positive electrode dot diagrams. ..

(Average grain size)
In the EBSD measurement on the rolled surface of each test material, the measurement was performed in the range of 800 μm×1600 μm under the condition of scan step 0.1 μm. In the analysis of the measurement results, the average crystal grain size was calculated from all the crystal grains in the measurement range. The analysis software OIM Analysis (trade name) manufactured by TSL was used for the analysis of the crystal grain size. The information obtained in the analysis of crystal grains by EBSD includes information up to a depth of several tens nm where the electron beam penetrates the sample. Further, it is preferable that the measurement position in the plate thickness direction is near a position ⅛ to ½ times the plate thickness t from the sample surface.

(Longitudinal elastic modulus)
From each test material, a direction RD parallel to the rolling direction, a plate width direction TD (direction orthogonal to the rolling direction RD), and a direction rotated at every 10° from RD to TD, respectively, JIS It is processed into a test piece of Z2201-13B and measured according to JIS Z2241. For the tensile test, an autograph universal testing machine AG-10KTD manufactured by Shimadzu Corporation was used. Stress was applied in the length direction of the test piece by a tensile tester, and the proportional constant of strain and stress was obtained. The strain amount of 80% of the strain amount at yield was taken as the maximum displacement amount, the displacement amount was divided into 10 parts, and the proportional constant of strain and stress was obtained as Young's modulus from the measured values at the 10 points. ..

(conductivity)
The electrical conductivity (EC) of each test material was calculated from the numerical value of the specific resistance measured in a constant temperature bath maintained at 20° C. (±0.5° C.) by the four-terminal method based on JIS H0505. The distance between the terminals was 100 mm. When the electrical conductivity of the plate material was 80% IACS or more, it was judged as good, and when it was less than 80% IACS, it was judged as poor.

(Tensile strength)
Three test pieces of JIS Z2201-13B cut out from the rolling parallel direction were measured according to JIS Z2241 and the average value was shown. For the tensile test, an autograph universal testing machine AG-10KTD manufactured by Shimadzu Corporation was used. When the tensile strength of the plate material was 300 MPa or more, it was judged as good, and when it was less than 300 GPa, it was judged as bad.

As shown in Tables 1 and 2, Examples 1 to 10 of the present invention each have an alloy composition range, a manufacturing condition, a crystal grain orientation distribution function (ODF) of φ2=0°, and Φ=0 to 0. Since the orientation density in the range of 10°, φ1=0 to 90°, and the average crystal grain size are all within the proper ranges, they were rotated every 10° from the rolling parallel direction (RD) to the rolling vertical direction (TD). The average longitudinal elastic modulus, conductivity, and tensile strength are excellent.

On the other hand, Comparative Examples 1 to 9 have alloy composition ranges, manufacturing conditions, and crystal grain orientation distribution functions (ODF) of φ2=0°, φ=0 to 10°, and φ1=0 to 90°. The average value of the longitudinal elastic modulus taken in the direction rotated at every 10° from the rolling parallel direction (RD) to the rolling vertical direction (TD) is high and out of the appropriate range, and either the conductivity or the tensile strength, or Both are outside the proper range.

Claims (5)

The content of Sn is 0 to 0.5 mass %, the balance is copper and unavoidable impurities, and the Eulerian angle of the crystal grain orientation distribution function (ODF: crystal orientation distribution function) is φ2=0 when the plate surface is subjected to EBSD. °, [Phi = 0 from 10 °, the orientation density in the range of .phi.1 = 0 of 90 ° is less than 40 der 3.0 or more on average is,
A copper alloy sheet material for heat dissipation member, having an average longitudinal elastic modulus of 130 GPa or less taken in a direction rotated at every 10° from a rolling parallel direction (RD) to a rolling vertical direction (TD) . The content of Sn is 0 to 0.5 mass %, the balance is copper and unavoidable impurities, and the Eulerian angle of the crystal grain orientation distribution function (ODF: crystal orientation distribution function) is φ2=0 when the plate surface is subjected to EBSD. °, [Phi = 0 from 10 °, towards position density in the range of .phi.1 = 0 of 90 ° is less than the average of 5.0 or more 40, 10 ° over a rolling vertically (TD) from the direction parallel to the rolling direction (RD) The copper alloy plate material for a heat dissipation member according to claim 1 , wherein the average value of the longitudinal elastic modulus taken in the direction of every rotation is 130 GPa or less. The copper alloy plate material according to claim 1 or 2, wherein the average crystal grain size is 1 µm to 100 µm. The copper alloy sheet material according to any one of claims 1 to 3, which has a tensile strength of 300 MPa or more. It is a manufacturing method of the copper alloy plate material for heat dissipation members according to any one of claims 1 to 4,
Casting a copper alloy having the alloy composition, performing a homogenizing heat treatment for the material to be rolled obtained by rolling,
After the homogenizing heat treatment, hot rolling the material to be rolled,
Cooling after the hot rolling,
After the cooling, chamfering both sides of the rolled material,
Cold rolling so that the total working rate becomes 75% or more after the surface cutting,
As the first annealing,
Heat treatment at a temperature rising rate of 10 to 100° C./sec, an ultimate temperature of 100 to 400° C., a holding time of 1 to 900 sec, and cooling at a cooling rate of 10 to 100° C./sec ;
Performing cold rolling after the first annealing,
As the second annealing,
Heat treatment at a temperature rising rate of 10 to 200° C./second, an ultimate temperature of 300 to 800° C., a holding time of 10 to 3600 seconds, and cooling at a cooling rate of 10 to 200° C./second ;
Then, finish rolling, low-temperature annealing, pickling, and polishing are performed, and a method for producing a copper alloy sheet for a heat dissipation member.

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