Copper material and insulating circuit board

Abstract

To provide a copper material having minimal presence of basic carbonate compounds on the surface and exhibiting excellent bonding strength with resin, and to provide an insulating circuit board comprising the copper material.SOLUTION: A copper material has a roughened surface with an Sdr (developed interfacial area ratio) of 35% or more. On the roughened surface, the difference between the maximum and minimum of the wavenumber differential of absorbance measured by FT-IR from 1300 cm-1 or more to 1900 cm-1 or less is 0.0004 or less. It is preferable that the roughened surface has an Sdr of 50% or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a copper material and an insulating circuit board. [Background Technology]

[0002] A power module, an LED module, and a thermoelectric module are provided with an insulating circuit board. The insulating circuit board has an insulating layer, and a circuit layer made of a conductive material is formed on one side of the insulating layer. As the material for the insulating layer, an insulating resin has been proposed, and as the conductive material for forming the circuit layer, a copper material has been proposed. When using the insulating circuit board, there is a risk of peeling between the insulating layer (resin) and the circuit layer (copper material), so there is a demand for a copper material that bonds with the resin with high strength.

[0003] As a method for increasing the bonding strength between resin and copper material, a method for treating the surface of a copper layer is known in which the surface of the copper layer is subjected to an etching-type chemical roughening treatment so as to generate unevenness with a valley-to-peak height of more than 5 μm, and the treated surface is then subjected to a blackening treatment (Patent Document 1). The surface of the copper layer roughened by this method is given micron-order unevenness by the etching-type chemical roughening treatment, and further given submicron-order fine unevenness by the blackening reduction treatment. As a result, the copper layer has a fine and complex surface property, and when the copper layer and resin are bonded, the anchoring effect is increased due to the fine and complex surface property of the copper layer.

Prior art documents

Patent documents

[0004]

Patent document 1

Summary of the invention

Problems to be solved by the invention

[0005] However, the surface of copper material contains Cu,Cu 2O, CuO and CuCO 3 ·Cu(OH) 2 etc. are known to exist, and in particular, CuCO 3 ·Cu(OH) 2 The basic carbonic acid compound represented by has been shown by theoretical calculations to reduce the bonding strength between the copper material and the resin. In Patent Document 1, the basic carbonic acid compound was not removed, and the bonding strength between the copper material and the resin was reduced.

[0006] The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a copper material having almost no basic carbonic acid compound on the surface and having excellent bonding strength with a resin, and an insulating circuit board including the copper material.

Means for Solving the Problems

[0007] In order to solve the above problems, the copper material of Aspect 1 of the present invention has a roughened surface with an Sdr (developed interface area ratio) of 35% or more. In the roughened surface, 1300 cm measured by FT-IR -1 or more and 1900 cm -1 The difference between the maximum value and the minimum value of the wavenumber derivative value of the absorbance below is 0.0004 or less.

[0008] According to the copper material of Aspect 1 of the present invention, it has a roughened surface with an Sdr (developed interface area ratio) of 35% or more. The anchoring effect on this roughened surface is increased, and the bonding strength is increased by using the roughened surface as the bonding surface. And, in the roughened surface, 1300 cm measured by FT-IR -1 or more and 1900 cm -1 The difference between the maximum value and the minimum value of the wavenumber derivative value of the absorbance below is 0.0004 or less, and almost no basic carbonic acid compound exists on the roughened surface. Thereby, it is possible to prevent the basic carbonic acid compound from reducing the bonding strength between the copper material and the resin.

[0009] The copper material of Aspect 2 of the present invention is characterized in that, in the copper material of Aspect 1, the Sdr on the roughened surface is 50% or less. According to the copper material of Embodiment 2 of the present invention, since Sdr on the roughened surface is 50% or less, it is not necessary to perform roughening treatment more than necessary, and the copper material can be efficiently manufactured. Further, even when Sdr on the roughened surface is 50% or less, sufficient bonding strength between the copper material and the resin can be ensured.

[0010] The copper material of Embodiment 3 of the present invention is characterized in that, in the copper material of Embodiment 1 or Embodiment 2, when washing treatment is performed with hydrochloric acid for 60 seconds, the change rate of Sdr before and after the washing treatment is 15% or less. According to the copper material of Embodiment 3 of the present invention, when the copper material is washed with hydrochloric acid for 60 seconds and the change rate of Sdr is 15% or less, a high Sdr can be maintained even after washing the copper material, and the bonding strength of the copper material can be kept high. Note that the change rate of Sdr is Sdr after washing (%) - Sdr before washing (%).

[0011] The copper material of Embodiment 4 of the present invention is characterized in that, in any one of the copper materials of Embodiments 1 to 3, convex portions are formed on the roughened surface, and the convex portions are provided with widened portions whose widths gradually increase toward the tip side in the protruding direction. According to the copper material of Embodiment 4 of the present invention, since the roughened surface is provided with widened portions whose widths gradually increase toward the tip side in the protruding direction, resin or the like to be joined to the copper material is surely engaged with the convex portions, and the bonding strength between the copper material and resin or the like can be increased.

[0012] The copper material of Embodiment 5 of the present invention is characterized in that, in any one of the copper materials of Embodiments 1 to 4, it has a plate shape, and both of its surfaces are the roughened surfaces. According to the copper material of Embodiment 5 of the present invention, since it has a plate shape and both of its surfaces are the roughened surfaces, it is possible to improve the bonding strength with resin on both surfaces of the copper material.

[0013] The insulating circuit board according to Aspect 6 of the present invention is an insulating circuit board including an insulating resin layer and a circuit layer formed on one surface of the insulating resin layer, wherein the circuit layer is formed by joining any one of the copper materials according to Aspect 1 to Aspect 5 to one surface of the insulating resin layer, and the roughened surface of the copper material constituting the circuit layer is the joint surface with the insulating resin layer. According to the insulating circuit board of Aspect 6 of the present invention, the circuit layer formed on one surface of the insulating resin layer is made of any one of the copper materials according to Aspect 1 to Aspect 5, and the roughened surface of the copper material constituting the circuit layer is the joint surface with the insulating resin layer. Therefore, the bonding strength between the circuit layer and the insulating resin layer is high, and it can be used stably.

[0014] The insulating circuit board according to Aspect 7 of the present invention is an insulating circuit board including an insulating resin layer, a circuit layer formed on one surface of the insulating resin layer, and a heat dissipation layer formed on the other surface of the insulating resin layer, wherein at least one of the circuit layer and the heat dissipation layer is formed by joining any one of the copper materials according to Aspect 1 to Aspect 5 to the insulating resin layer, and the roughened surface of the copper material constituting at least one of the circuit layer and the heat dissipation layer is the joint surface with the insulating resin layer. According to the insulating circuit board of Aspect 7 of the present invention, at least one of the circuit layer and the heat dissipation layer is formed by joining any one of the copper materials according to Aspect 1 to Aspect 5 to the insulating resin layer, and the roughened surface of the copper material constituting at least one of the circuit layer and the heat dissipation layer is the joint surface with the insulating resin layer. Therefore, the bonding strength between at least one of the circuit layer and the heat dissipation layer and the insulating resin layer is high, and it can be used stably.

Effects of the Invention

[0015] According to the present invention, it is possible to provide a copper material having almost no basic carbonate compound on the surface and excellent bonding strength with a resin, and an insulating circuit board including this copper material.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0017] Hereinafter, a copper material and an insulating circuit board which are embodiments of the present invention will be described with reference to the attached drawings. The insulating circuit board 1 is used, for example, for a power module, an LED module, and a thermoelectric module, and is formed by joining a copper material 11 and a resin layer 21. FIG. 1 shows a copper material 11 which is an embodiment of the present invention and an insulating circuit board 1 using this copper material 11.

[0018] The insulating circuit board 1 shown in FIG. 1 includes a copper material 11 and a resin layer 21 formed on one surface (the upper surface in FIG. 1) of this copper material 11. The copper material 11 also includes a joint surface 12 with the resin layer 21.

[0019] The copper material 11 is used as a circuit layer or a heat dissipation layer. In the present embodiment, this copper material 11 has an Sdr (developed interface area ratio) of 35% or more, and the difference between the maximum value and the minimum value of the wavenumber differential value of the absorbance at 1300 cm -1 or more and 1900 cm -1 measured by FT-IR is 0.0004 or less.

[0020] Sdr (expansion interface area ratio) is an index indicating the increase ratio of the surface area due to unevenness. When Sdr is large, it means that the convex portions are formed uniformly and densely. In addition, since the joint strength increases, the Sdr of the copper material is preferably 40% or more, and more preferably 45% or more. On the other hand, when the Sdr of the copper material is sufficiently large, even if a basic carbonate compound is present on the surface, the joint strength becomes sufficiently large due to the roughened structure. Therefore, the removal effect of the basic carbonate compound is greatly exerted in the case of a roughened state with a small Sdr. Therefore, from the viewpoint of the removal effect of the basic carbonate compound, the Sdr of the copper material is desirably 50% or less.

[0021] In this embodiment, the reason for defining the measurement result of FT-IR of the copper material 11 as described above will be described with reference to FIG. 2. FIG. 2 shows the structures of copper and copper-containing compounds found to be present on the surface of the copper material by surface analysis. Among these copper and compounds, CuCO 3 ·Cu(OH) 2 (basic carbonate compound) intervenes at the joint surface 12 between the resin layer 21 of the copper material 11, it has been clarified by theoretical calculation that the joint strength decreases.

[0022] When measuring the FT-IR of the copper material in which this CuCO 3 ·Cu(OH) 2 is present on the surface, bands are observed in the wavenumber region of 1300 cm -1 or more and 1900 cm -1 or less. That is, the copper material 11 in which the difference between the maximum value and the minimum value of the wavenumber derivative value of the absorbance at 1300 cm -1 or more and 1900 cm -1 or less measured by FT-IR is 0.0004 or less means that there is almost no CuCO 3 ·Cu(OH) 2 on the surface. The copper material 11 that satisfies the regulation of this FT-IR measurement result has a high joint strength with the resin layer 21 because it cannot reduce the joint strength with the resin layer 21 due to CuCO 3 ·Cu(OH) 2 .

[0023] When the resin layer 21 uses the insulating circuit board 1 as an insulating circuit board, it prevents the electrical connection between the copper material 11 and a metal substrate (not shown). In the present embodiment, it is composed of a thermosetting resin having insulating properties. In the present embodiment, in order to ensure the strength of the resin layer 21 and ensure the thermal conductivity, a thermosetting resin containing a filler is used. Here, as the filler, for example, alumina, boron nitride, aluminum nitride, silica, magnesium oxide, etc. can be used. Also, as the thermosetting resin, an epoxy resin, a polyimide resin, etc. can be used. In the present embodiment, the resin layer 21 is composed of an epoxy resin containing boron nitride as a filler.

[0024] Also, when the copper material 11 is washed with hydrochloric acid for 60 seconds, it is preferable that the change rate of Sdr before and after the washing treatment is 15% or less. When Sdr decreases due to the washing treatment, the bonding strength with the resin layer 21 decreases. Therefore, the change rate of Sdr before and after the washing treatment is preferably 10% or less, more preferably 5% or less, and particularly preferably 3% or less. Since it is desirable that there is no change, the lower limit of the change rate of Sdr before and after the washing treatment is 0% or more.

[0025] Here, the bonding surface 12 between the copper material 11 and the resin layer 21 in the present embodiment will be described with reference to FIG. 3. The bonding surface 12 is formed on the surface of the copper material 11 in the present embodiment on the side (the upper side in FIG. 1) that bonds to the resin layer 21, and convex portions 13 are formed on the bonding surface 12. As shown in FIG. 3, it is preferable that the convex portion 13 has a widened portion 13a whose width gradually increases toward the tip side in the protruding direction. When the widened portion 13a is provided, the resin layer 21 can be surely engaged with the convex portion 13, and the bonding strength between the copper material 11 and the resin layer 21 can be improved.

[0026] According to the copper material 11 according to the present embodiment configured as described above, the Sdr (developed interface area ratio) is 35% or more, and the wavenumber differential value of the absorbance at 1300 cm -1 or more and 1900 cm -1 The difference between the maximum value and the minimum value of the wavenumber differential value of the absorbance below is 0.0004 or less. Therefore, the convex portions are formed uniformly and densely, and there is almost no basic carbonate compound on the surface of the copper material 11, so the bonding strength with the resin layer 21 is increased.

[0027] In the present embodiment, when the copper material 11 is washed with hydrochloric acid for 60 seconds and the change rate of Sdr before and after the washing treatment is 15% or less, the Sdr can be kept high, so the bonding strength with the resin layer 21 can be increased.

[0028] Further, in the present embodiment, when the convex portion 13 of the bonding surface 12 of the copper material 11 with the resin layer 21 includes the widened portion 13a, the resin layer 21 will surely engage with the convex portion 13, and the adhesion between the copper material 11 and the resin layer 21 can be improved.

[0029] As described above, the present embodiment has been described, but the present invention is not limited thereto, and can be appropriately changed without departing from the technical idea of the invention.

Example

[0030] Hereinafter, the results of the confirmation experiment conducted to confirm the effects of the present invention will be described.

[0031] (Example 1 of the present invention) A copper material (80 mm × 20 mm × thickness 5.0 mm) with an Sdr of 38.5% was washed with hydrochloric acid for 60 seconds. The Sdr after the washing treatment was 37.1%. In addition, the roughened surface of the copper material was observed using a laser microscope OLS5000 with an objective lens magnification of 100 times in a measurement range of 129 μm × 129 μm, and processing was performed to remove the inclination and noise of the sample, and the developed interface area ratio Sdr on the roughened surface was calculated. The calculation method used the calculation formula of JIS B 0681-2:2018. When the FT-IR of the copper material after this washing was measured, 1300 cm -1 above 1900 cm -1 The difference between the maximum value and the minimum value of the wavenumber derivative value of the absorbance below was 0.000299.

[0032] In addition, the FT-IR measurement of the copper material was carried out by the high-sensitivity reflection (RAS) method. The high-sensitivity reflection (RAS) method, different from ordinary total reflection (ATR), can sensitively detect the presence of organic deposits on the metal substrate. As the FT-IR device, a bench-top infrared microscope Nicolet iS5 manufactured by Thermo Fisher Scientific was used. Also, as the RAS attachment, a high-sensitivity reflection measurement device Refractor2 manufactured by Harrick Scientific Products Inc. was used.

[0033] This copper material was joined to an epoxy resin as shown in Fig. 4. The heating temperature was 200 °C, and the holding time at the heating temperature was 60 minutes. The copper material was laminated on the epoxy resin and joined by its own weight and heating. Then, a lap shear test was performed to evaluate the bonding strength between the copper material and the epoxy resin. In addition, the lap shear test was carried out using the test piece shown in Fig. 4 in accordance with the "Test Method for Tensile Shear Adhesion Strength of Adhesives - Rigid Adherends" of JIS K 6850:1999. It was carried out using a universal material testing machine 68TM-50 manufactured by Instron under the condition of a tensile speed of 1.0 mm / min. Also, 4,4'-methylenebis(N,N-diglycidylaniline) was used as the epoxy resin, and imidazole was used as the curing agent for the epoxy resin.

[0034] (Example 2 of the present invention, Comparative Examples 1 to 5) In Example 2 of the present invention and Comparative Examples 1 to 5, the Sdr at the time before the cleaning treatment, the liquid used for the cleaning treatment, and the time of the cleaning treatment were set to conditions different from those in Example 1 of the present invention, and the measurement of Sdr, the measurement of FT-IR, and the lap shear test were performed after the cleaning treatment. The results are shown in Table 1. In the column of FT-IR, the difference between the maximum value and the minimum value of the wavenumber derivative value of the absorbance at 1300 cm -1 or more and 1900 cm -1 or less is described. In the column of the evaluation result, "○" is described when the epoxy resin did not peel off from the copper material up to 23 MPa or more in the lap shear test, and "×" is described when it peeled off at less than 23 MPa. Note that in Comparative Example 2, the cleaning treatment was not performed. Also, in Comparative Examples 4 and 5, since the value of Sdr was low, the measurement of FT-IR was not performed.

[0035]

Table 1

[0036] In Examples 1 and 2 of the present invention, the Sdr after the cleaning treatment was 35% or more, and the difference between the maximum value and the minimum value of the wavenumber derivative value of the absorbance at 1300 cm -1 or more and 1900 cm -1 or less was 0.0004 or less, that is, CuCO 3 ·Cu(OH) 2 was removed from the surface of the copper material. As a result of the lap shear test, the copper material and the epoxy resin did not peel off up to 23 MPa or more, and the copper material had a sufficiently high bonding strength with the resin.

[0037] In Comparative Example 1, since the Sdr was less than 35% before the cleaning treatment, it was also less than 35% after the cleaning treatment. As a result of the lap shear test, the copper material and the epoxy resin peeled off at less than 23 MPa, indicating that the bonding strength with the resin was lower than that of the copper materials in Examples 1 and 2 of the present invention.

[0038] In Comparative Example 2, no cleaning treatment was performed. In Comparative Example 3, the cleaning treatment was performed for only 10 seconds. In Comparative Examples 2 and 3, the difference between the maximum value and the minimum value of the wavenumber derivative of the absorbance at 1300 cm -1 or higher and 1900 cm -1 or lower was 0.0004 or higher, indicating that CuCO 3 ·Cu(OH) 2 was not completely removed from the surface of the copper material. The result of the lap shear test was less than 23 MPa, indicating that the copper material and the epoxy resin were peeled off, and the bonding strength with the resin was lower than that of the copper materials of Examples 1 and 2 of the present invention.

[0039] In Comparative Example 4, nitric acid was used instead of hydrochloric acid for the cleaning treatment. In Comparative Example 5, persulfuric acid was used for the cleaning treatment. In Comparative Examples 4 and 5, the Sdr after the cleaning treatment was less than 35%, indicating that the Sdr would decrease too much without using hydrochloric acid. The result of the lap shear test was less than 23 MPa, indicating that the copper material and the epoxy resin were peeled off, and the bonding strength with the resin was lower than that of the copper materials of Examples 1 and 2 of the present invention.

[0040] As a result of the above confirmation experiments, according to the present invention, it was confirmed that it is possible to provide a copper material having almost no basic carbonate compound on the surface and having excellent bonding strength with a resin, and an insulating circuit board provided with this copper material.

Explanation of Reference Numerals

[0041] 1 laminate 11 copper material 12 bonding surface 13 convex portion 13a width portion 21 resin layer

Claims

1. The developed interface has a roughened surface having an Sdr (developed interface area ratio) of 35% or more, and the roughened surface has a surface roughness of 1300 cm measured by FT-IR. －１ More than 1900cm －１ A copper material characterized in that the difference between the maximum and minimum wavenumber derivative values ​​of absorbance is 0.0004 or less.

2. 2. The copper material according to claim 1, wherein Sdr on the roughened surface is 50% or less.

3. 2. The copper material according to claim 1, wherein when the copper material is washed with hydrochloric acid for 60 seconds, the rate of change in Sdr before and after the washing treatment is 15% or less.

4. 2. The copper material according to claim 1, wherein a convex portion is formed on the roughened surface, and the convex portion has a widening portion whose width gradually increases toward a tip side in a protruding direction.

5. 2. The copper material according to claim 1, which is in the form of a plate, both sides of which are roughened.

6. An insulating circuit board comprising an insulating resin layer and a circuit layer formed on one surface of the insulating resin layer, 6. An insulating circuit board, comprising: a circuit layer formed by bonding the copper material according to claim 1 to one surface of the insulating resin layer; and a roughened surface of the copper material constituting the circuit layer being a bonding surface with the insulating resin layer.

7. An insulating circuit board comprising an insulating resin layer, a circuit layer formed on one surface of the insulating resin layer, and a heat dissipation layer formed on the other surface of the insulating resin layer, At least one of the circuit layer and the heat dissipation layer is formed by bonding the copper material according to any one of claims 1 to 5 to the insulating resin layer, 13. An insulating circuit board, comprising: a copper material constituting at least one of said circuit layer and said heat dissipation layer, said roughened surface being a bonding surface with said insulating resin layer.

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