WO2013008651A1

WO2013008651A1 - Circuit board and electronic device

Info

Publication number: WO2013008651A1
Application number: PCT/JP2012/066753
Authority: WO
Inventors: 石峯　裕作; 森山　正幸; 健司小松原
Original assignee: 京セラ株式会社
Priority date: 2011-07-14
Filing date: 2012-06-29
Publication date: 2013-01-17
Also published as: JP5665988B2; JPWO2013008651A1

Abstract

[Problem] To provide a circuit board capable of minimizing insulation breakdown between circuit members, having superior heat dissipation characteristics, and in which the circuit members are firmly bonded to a support substrate, and an electronic device having an electronic component mounted on the circuit member on the circuit board. [Solution] A circuit board (10) has multiple circuit members (2) bonded and arranged via a first bonding layer (3) on a first principal surface of a support substrate (1) comprised of a ceramic sintered compact. A projection (1a) is provided in an area for arranging the circuit member and an area between the circuit members on the first principal surface. The average height of the projection (1a₁) provided in the area between the circuit members is lower than the average height of the projection (1a₂) provided in the area for arranging the circuit member.

Description

Circuit board and electronic device

The present invention relates to a circuit board in which a plurality of circuit members are bonded to a main surface of a support substrate made of a ceramic sintered body and an electronic device in which electronic components are mounted on the circuit members in the circuit board. is there.

In recent years, as components of semiconductor devices, insulated gate bipolar transistor (IGBT) elements, intelligent power module (IPM) elements, metal oxide field effect transistor (MOSFET) elements, light emitting diode (LED) elements, free Various electronic components such as a wheeling diode (FWD) element, a giant transistor (GTR) element, a semiconductor element such as a Peltier element, a sublimation thermal printer head element, and a thermal ink jet printer head element are mounted on a circuit member of a circuit board. Electronic devices are used.

The circuit member on which this electronic component is mounted is made of a metal having a high thermal conductivity and is bonded to the main surface of a support substrate made of insulating ceramics. The circuit board provided with the circuit member has a high bonding strength that prevents the circuit member from being peeled off from the support substrate by a thermal cycle by repeatedly operating and stopping the electronic component mounted on the circuit member, and during operation of the electronic component. There is a need for excellent heat dissipation characteristics that can quickly release the generated heat.

As such a circuit board, for example, in Patent Document 1, in a silicon nitride sintered body substrate substantially composed of silicon nitride particles and a grain boundary phase, the silicon nitride particles and the grain boundary phase on the surface of the sintered body substrate are When the total area ratio is 100%, the area ratio of the silicon nitride particles is 70 to 100%, the peak of the maximum height of the silicon nitride particles exposed on the surface, and the minimum of the silicon nitride particles or the grain boundary phase A circuit board made of Al or Cu is mounted on a silicon nitride substrate for circuit mounting having a surface property of a height difference (L) of 1.5 to 15 μm and a center line average roughness (Ra) of 0.2 to 5 μm. A circuit board formed by bonding has been proposed.

Japanese Patent No. 3539634

The silicon nitride substrate for circuit mounting that constitutes the circuit substrate proposed in Patent Document 1 has its surface properties adjusted in order to improve the bonding strength with the circuit member. It is described that the grain boundary phase is mechanically removed by machining such as blasting, grid blasting or hydroblasting. When the grain boundary phase is mechanically removed, the surface of the silicon nitride substrate for circuit mounting is described. The existing silicon nitride particles are also subjected to mechanical impact. As a result, the silicon nitride particles on the surface of the silicon nitride substrate for circuit mounting are easy to degranulate, and the silicon nitride particles may be degranulated and the bonding strength may decrease due to the thermal cycle caused by repeated operation and stoppage of electronic components. there were.

In addition, if the grain boundary phase is to be removed by machining, the abrasive grains used in these machining processes may pierce the grain boundary phase, and the abrasive grains that have pierced the grain boundary layer can be easily removed by washing. Therefore, when a circuit member is bonded to such a surface, a sufficient anchor effect cannot be obtained due to voids generated around the pierced abrasive grains, and the bonding strength may not be increased.

As described above, when the surface properties are adjusted by the above-described machining, there is a factor that the bonding strength is lowered. In recent years, a circuit that can respond to the mounting of electronic components that generate higher heat than before when operating. Since it needs to be a substrate, higher bonding strength and superior heat dissipation characteristics are required. Further, since the interval between circuit members is becoming narrower due to high integration, there is a need for a circuit board that is less likely to cause dielectric breakdown between circuit members.

The present invention has been devised to satisfy the above-described requirements, and it is difficult to cause dielectric breakdown between circuit members, has excellent heat dissipation characteristics, and a circuit board in which the circuit member is firmly bonded to a support substrate and An electronic device in which an electronic component is mounted on a circuit member in the circuit board is provided.

In the circuit board of the present invention, a plurality of circuit members are bonded to a first main surface of a support substrate made of a ceramic sintered body via a first bonding layer, and the circuit on the first main surface is arranged. Projections are present in the member arrangement region and the inter-circuit member region, and the average height of the projections existing in the inter-circuit member region is lower than the average height of the projections existing in the circuit member arrangement region It is.

The electronic device of the present invention is characterized in that an electronic component is mounted on the circuit member of the circuit board of the present invention having the above-described configuration.

According to the circuit board of the present invention, the average height of the protrusions existing in the circuit member arrangement area is lower than the average height of the protrusions existing in the circuit member arrangement area. It is possible to make the dielectric breakdown between the circuit members less likely to occur due to adhesion of metal powder, moisture, or the like to the protrusions existing in the region between the circuit members than when the height is higher or the same. Further, since the protrusions are present in the inter-circuit member region, the heat dissipation characteristics can be improved as compared with the case where the protrusions are not present. Further, in the relationship between the average height of the protrusions existing in the circuit member arrangement area and the average height of the protrusions existing in the area between the circuit members, the average height of the protrusions existing in the circuit member arrangement area is Since it is higher than the average height of the existing protrusions, when the support substrate and the circuit member are bonded by the first bonding layer, the support substrate and the circuit member can be firmly bonded by a high anchor effect.

In addition, according to the electronic device of the present invention, the circuit board of the present invention on which electronic components are mounted is less likely to cause dielectric breakdown between circuit members, has excellent heat dissipation characteristics, and the circuit member is firmly bonded to the support substrate. Therefore, a highly reliable electronic device can be obtained.

An example of the circuit board of the present embodiment is shown, (a) is a plan view, and (b) is a cross-sectional view taken along line A-A 'in (a). FIG. 1 schematically shows an example of protrusions present on the first main surface of a support substrate constituting the circuit board of the example shown in FIG. 1, (a) is a plan view, and (b) is a BB line in (a). It is sectional drawing in line ', (c), (d) is the elements on larger scale of the C section and D section in (b). The other example of the circuit board of this embodiment is shown. (A) is a top view and (b) is a sectional view in the G-G 'line in (a). Another example of the circuit board of the present embodiment is shown, (a) is a plan view, (b) is a cross-sectional view taken along line HH ′ in (a), and (c) is a bottom view. is there. FIG. 4 schematically shows an example of protrusions present on each main surface of a support substrate constituting the circuit board of the example shown in FIG. 4, (a) is a plan view, and (b) is a line JJ ′ in (a). It is sectional drawing in a line, (c), (d) is the elements on larger scale of the K section and the L section in (b). Another example of the circuit board of the present embodiment is shown, (a) is a plan view, (b) is a cross-sectional view taken along the line PP ′ in (a), and (c) is a bottom view. is there. An example of the electronic device of the present embodiment is shown, in which (a) is a plan view, (b) is a cross-sectional view taken along line Q-Q 'in (a), and (c) is a bottom view.

Hereinafter, an example of the circuit board and the electronic device of the present embodiment will be described. 1A and 1B show an example of a circuit board according to the present embodiment, in which FIG. 1A is a plan view and FIG. 1B is a cross-sectional view taken along line A-A ′ in FIG. A circuit board 10 of the example shown in FIG. 1 is arranged with circuit members 2 (2a, 2b) bonded to a first main surface of a support substrate 1 made of a ceramic sintered body via a first bonding layer 3. The circuit board 10 is.

The support substrate 1 constituting the circuit board 10 of the example shown in FIG. 1 is made of a flat ceramic sintered body, and has a length (X direction shown in FIG. 1) of, for example, 20 mm or more and 200 mm or less. The width (Y direction shown in FIG. 1) is 10 mm or more and 120 mm or less. In addition, although thickness changes with uses, it is suitable for it to be 0.2 mm or more and 1.0 mm or less in order to make durability and withstand voltage high and to suppress thermal resistance.

Further, the

circuit members

2a and 2b constituting the circuit board 10 of the example shown in FIG. 1 are mainly composed of copper, for example, and the length (X direction shown in FIG. 1) is 8 mm or more. It is 85 mm or less, and the width (Y direction shown in FIG. 1) is 8 mm or more and 100 mm or less. The thickness of the

circuit members

2a and 2b is determined by the magnitude of current flowing through the

circuit members

2a and 2b, the amount of heat generated by electronic components (not shown) mounted on the

circuit members

2a and 2b, and the thickness is 0.5 mm or more, for example. 5 mm or less.

Further, when the

circuit members

2a and 2b have the same size as in the example shown in FIG. 1, it is possible to reduce the stress bias generated in the support substrate 1 when the

circuit members

2a and 2b are joined. Needless to say, although the warpage of the support substrate 1 generated in the process can be suppressed, the

circuit members

2a and 2b may have different sizes. Further, the first bonding layer 3 is formed by heating a brazing material as a bonding material.

2 schematically shows an example of protrusions present on the first main surface of the support substrate constituting the circuit board of the example shown in FIG. 1, (a) is a plan view, and (b) is (a). FIG. 3B is a cross-sectional view taken along line BB ′ in FIG. 2, and FIGS. 3C and 3D are enlarged views of portions C and D in FIG. As shown in FIG. 2, the circuit board 10 of the present embodiment has protrusions 1 a in the circuit member arrangement area and the inter-circuit member area on the first main surface of the support board 1 constituting the circuit board 10, the average height of the protrusions 1a ₁ existing in the region, is characterized by lower than the average height of the protrusions 1a ₂ present in the circuit member arrangement area. In addition, the circuit member arrangement | positioning area | region in this embodiment refers to the part shown with a broken line in Fig.2 (a), for example, and the area | region between circuit members is between the parts shown with a broken line in Fig.2 (a). Refers to that. Further, the average height of the projections 1a _1, and that the average value of the height E of the projections 1a _1, the average height of the protrusions 1a _2, is that the average value of the height F of the projection 1a _2.

Here, the protrusions 1a ₁ and 1a ₂ shown in FIGS. 2C and 2D show a case where the main component is made of silicon nitride, and the main component of the protrusions 1a ₁ and 1a ₂ is made of silicon nitride. Sometimes, the protrusions 1a ₁ and 1a ₂ include needle-like crystals 1c and columnar crystals 1d extending from the raised portions 1b, and when the main component of the other material, for example, the protrusions 1a ₁ and 1a ₂ is made of aluminum oxide or aluminum nitride, The protrusions 1a ₁ and 1a ₂ are composed only of the raised portions 1b. The main component and protrusions 1a _1, 1a _2, and those containing more than 70 wt% of the components constituting the projection 1a _1, 1a _2, for the identification of components, a thin film X-ray diffraction method or a transmission electron microscopy For example, the content of silicon (Si) or aluminum (Al) is obtained by transmission electron microscopy, and this content is determined according to the identified component, and silicon nitride (Si ₃ N ₄ ), and can be calculated by converting into aluminum oxide (Al ₂ O ₃ ) or aluminum nitride (AlN).

The height F of the projection _1a 1, the height E and the projections 1a of the projections 1a ₁ regardless components 1a ₂ ₂ from non-raised portion, the raised portion 1b, needles 1c, one of the columnar crystals 1d The height up to the highest point. The heights E and F of the protrusions 1a ₁ and 1a ₂ can be obtained using an optical microscope with a magnification of 100 to 1000 times.

Specifically, after the portions including the protrusions 1a ₁ and 1a ₂ are cut out from the support substrate 1 and embedded in the resin, the fractured surface is polished by the cross-section polisher method and polished surfaces including the protrusions 1a ₁ and 1a ₂ respectively. Is made. Next, the heights E and F of the protrusions 1a ₁ and 1a _{2 on} the polished surface are measured using an optical microscope with a magnification of 100 to 1000 times. Then, each of the projections _1a 1, 1a 10 or more 20 or less measured per _2, the average value of the measured values and the average height of each projection _1a 1, 1a _2.

The circuit board 10 of the present embodiment is present in the circuit member arrangement region because the average height of the protrusions 1a ₁ existing in the inter-circuit member region is lower than the average height of the protrusions 1a ₂ existing in the circuit member arrangement region. It is less likely to cause dielectric breakdown between the circuit members 2 due to adhesion of metal powder, moisture, etc. to the projections 1a ₁ existing in the inter-circuit member region than when the average height of the projections 1a ₂ is higher or the same. be able to. Further, the presence of the protrusion 1a _{1 in the} inter-circuit member region can improve the heat dissipation characteristics as compared with the case where the protrusion 1a ₁ does not exist.

Further, in the relationship between the average heights of the projections 1a ₁ existing in the inter-circuit member region and the projections 1a ₂ existing in the circuit member arrangement region, the average height of the projections 1a ₂ existing in the circuit member arrangement region is Since it is higher than the average height of the protrusions 1a ₁ existing in the inter-member region, when the brazing material is used as the first bonding layer 3, the support substrate 1 and the circuit member 2 are firmly bonded by a high anchor effect. can do. Further, when the main component of the protrusion 1a ₂ is made of silicon nitride and a plurality of needle-like crystals 1c and columnar crystals 1d extend from the raised portion 1b, a higher anchor effect can be obtained, and the needle-like crystals 1c and columnar crystals are obtained. A higher anchor effect can be obtained when the direction in which 1d extends is not aligned.

The difference between the average heights of the protrusions 1a ₁ and 1a ₂ is preferably 4 μm or more. When the difference is within this range, the dielectric breakdown between the circuit members 2 hardly occurs in the circuit member arrangement region, and the heat dissipation characteristics The bonding strength can be further increased while improving the above. Upon firmly bond the supporting substrate 1 and the circuit member 2, it is preferred that the average height of the protrusions 1a ₂ is 16μm or more. The dimensions of the protrusion 1a ₂ are, for example, a width of 10 μm to 48 μm and a height of 16 μm to 52 μm. Note that the width is a measured value from an unraised portion to an unraised portion on both sides of the raised portion.

Also, the protrusions 1a ₂ in the circuit member arrangement region of the first main surface is preferably density of 48 / cm ² or more 502 pieces / cm ² or less. Here, the density represents the number of protrusions 1a ₂ in a predetermined area. When the density of the projections 1a ₂ in the circuit member arrangement region is within this range, the projections 1a ₂ are arranged at appropriate intervals without the projections 1a ₂ being scattered or aggregated. When the support substrate 1 and the circuit member 2 are joined together, a higher anchor effect is produced, and the circuit member 2 can be joined more firmly. In particular, the density is more preferably 102 / cm ² or more and 448 / cm ² or less. In this density calculation method, an optical microscope is used to observe the circuit member arrangement region on the first main surface at a magnification of 100 to 1000 times, for example, in a range of 170 μm × 170 μm, and the protrusion 1a in the range. ₂ is counted, and the number of projections 1a ₂ per 1 cm ² is calculated. Then, this operation is performed at a total of five locations while changing the observation region, and the average value of these may be used as the density.

3A and 3B show another example of the circuit board of the present embodiment. FIG. 3A is a plan view, and FIG. 3B is a cross-sectional view taken along line G-G ′ in FIG. In the circuit board 10 shown in FIG. 3, the first metal layer 4 is disposed between the first bonding layer 3 and the circuit member 2 constituting the circuit board 10 shown in FIG. In such a configuration, when the circuit member 2 has copper as a main component and the first metal layer 4 has copper as a main component, a low temperature is caused by the diffusion action of copper, which is the main component of the first metal layer 4. For example, since the support substrate 1 and the circuit member 2 can be bonded at a temperature of 300 ° C. or higher and 500 ° C. or lower, warpage generated in the support substrate 1 at the time of bonding can be suppressed. Therefore, the thick circuit member 2 can be joined, and the heat dissipation characteristics can be improved as compared with the circuit board 10 of the example shown in FIG.

In the circuit board 10 of the present embodiment, the kurtosis (R _ku ) of the first main surface of the support substrate 1 is preferably 2 or more, and the skewness (R _sk ) is preferably 1 or less. When the kurtosis (R _ku ) and the skewness (R _sk ) of the first main surface of the support substrate 1 are in this range, the anchor effect on the first bonding layer 3 becomes higher. Also in this configuration, the bonding strength between the support substrate 1 and the circuit member 2 can be further increased.

4A and 4B show still another example of the circuit board of the present embodiment. FIG. 4A is a plan view, FIG. 4B is a cross-sectional view taken along the line HH ′ in FIG. Is a bottom view. FIG. 5 schematically shows an example of protrusions present on each main surface of the support substrate constituting the circuit board of the example shown in FIG. 4, (a) is a plan view, and (b) is (a). ) Is a cross-sectional view taken along the line JJ 'in FIGS. 4A and 4B, and FIGS.

In addition to the configuration of the circuit board 10 shown in FIG. 1, the circuit board 10 of the example shown in FIG. 4 has a second main surface opposite to the first main surface of the support substrate 1 via a second bonding layer 6. And the heat radiating member 5 (5a, 5b) is joined.

The

heat dissipating members

5a and 5b constituting the circuit board 10 have a function of releasing heat generated by the operation of an electronic component (not shown), and the dimensions are, for example, length (X direction shown in FIG. 4). It is 8 mm or more and 96 mm or less, the width (Y direction shown in FIG. 4) is 8 mm or more and 100 mm or less, and the thickness is 0.5 mm or more and 5 mm or less. The second bonding layer 6 can be formed by heating a brazing material.

And in the support substrate 1 of the example shown in FIG. 5, the protrusion 1e exists in the heat radiating member arrangement | positioning area | region and the area between heat radiating members in the 2nd main surface of the support substrate 1, and the average of protrusion 1e ₁ which exists in the area | region between heat radiating members The height is preferably lower than the average height of the protrusions 1e ₂ existing in the heat dissipating member arrangement region. In addition, the heat radiating member arrangement | positioning area | region in this embodiment refers to the part shown with a broken line in Fig.5 (a), for example, and the area | region between heat radiating members is between the parts shown with a broken line in Fig.5 (a). Refers to that. Further, the average height of the projections 1e _1, is that the average value of the height M of the projection 1e _1, the average height of the projections 1e _2, is that the average value of the height N of the projections 1e _2. Further, the method of calculating the average height and average measurement method and the average value of the height of the projections 1e ₂ projections 1e ₁ is the same as the description in the height E and the height F of the projection 1a ₂ projections 1a ₁ described above is there.

Thus, the protrusions 1e are present in the heat dissipating member arrangement region and the heat dissipating member region on the second main surface of the support substrate 1, and the average height of the protrusions 1e ₁ existing in the heat dissipating member region is the heat dissipating member disposition region. when less than the average height of the projections 1e ₂ present is the average than when higher or equal than the height of the projections 1e ₂ existing in the heat radiating member arrangement region, a metal powder and water to the projection 1e ₁ present in the heat radiating member between the regions It is possible to make it difficult for dielectric breakdown to occur between the heat dissipating members 5 due to the adhesion of etc. Furthermore, by the projections 1e ₁ to the heat radiating member between the regions are present, further it is possible to improve the heat dissipation properties than when the projection 1e ₁ is not present, a projection 1e ₁ present in the heat radiating member between the regions , in the average height of the relation between the projections 1e ₂ existing in the heat radiating member arranged regions, the average height of the protrusions 1e ₂ existing in the heat radiating member arranged area, than the average height of the projections 1e ₁ present in the heat radiating member between the regions Therefore, when the brazing material is used as the second bonding layer 6, the support substrate 1 and the heat dissipation member 5 can be firmly bonded due to a high anchor effect.

In particular, the difference in average height between the protrusions 1e ₁ and 1e ₂ is preferably 4 μm or more. When the difference is within this range, it is difficult to cause dielectric breakdown between the circuit members 2 in the heat dissipating member arrangement region. In addition, the bonding strength can be further increased while improving the heat dissipation characteristics. Then, upon firmly bonding the supporting substrate 1 and the heat radiating member 3, it is preferable that the average height of the projections 1e ₂ is 16μm or more.

Also, when the FIG. 5 (c), the main component of the projection _1e 1, 1e ₂ shown in (d) of a silicon nitride, as illustrated in FIG. 5, the projections _1e 1, 1e ₂ extends from the raised portion 1f needle When the main crystals of the protrusions 1e ₁ and 1e ₂ are made of aluminum oxide or aluminum nitride, the protrusions 1e ₁ and 1e ₂ include only the raised portions 1f.

Moreover, it is preferable that the protrusions 1e ₂ in the heat dissipating member arrangement region of the second main surface have a density of 48 pieces / cm ² or more and 502 pieces / cm ² or less, thereby joining the heat dissipating member 5 more firmly. Can do. In addition, the calculation method of the density of the protrusion 1e ₂ is the same as the calculation method of the density of the protrusion 1a ₂ described above.

6A and 6B show still another example of the circuit board according to the present embodiment. FIG. 6A is a plan view, FIG. 6B is a cross-sectional view taken along the line PP ′ in FIG. Is a bottom view. The circuit board 10 of the example shown in FIG. 6 has a second bonding layer 6 and a second metal layer 7 on the second main surface which is the opposite surface of the first main surface of the support substrate 1 in addition to the configuration of FIG. Is a circuit board 10 to which the heat dissipating member 5 (5a, 5b) is joined. In such a configuration, when the heat radiating member 3 has copper as a main component and the second metal layer 7 has copper as a main component, the diffusion of copper, which is the main component of the second metal layer 7, causes a low temperature. For example, since the support substrate 1 and the heat radiating member 5 can be bonded at a temperature of 300 ° C. or higher and 500 ° C. or lower, warpage generated in the support substrate 1 at the time of bonding can be suppressed. Therefore, the thick heat dissipation member 5 can be joined, and the heat dissipation characteristics can be improved as compared with the circuit board 10 of the example shown in FIG.

In the circuit board 10 of the present embodiment, the kurtosis (R _ku ) of the second main surface of the support substrate 1 is preferably 2 or more, and the skewness (R _sk ) is preferably 1 or less. When the kurtosis (R _ku ) and the skewness (R _sk ) of the second main surface of the support substrate 1 are in this range, the anchor effect on the second bonding layer 6 becomes higher, so Also in this configuration, the bonding strength between the support substrate 1 and the heat dissipation member 5 can be further increased.

And when the circuit member 2 and the heat radiating member 5 consist of what has copper as a main component, since it is suitable that it is excellent in thermal conductivity, the oxygen-free copper which contains 90 mass% or more of copper It is preferable that it is made of any one of tough pitch copper and phosphorous deoxidized copper. Particularly, among oxygen-free copper, linear crystal oxygen-free copper containing 99.995% by mass or more of copper, single-crystal high-purity oxygen-free copper, and vacuum It is preferable to consist of any one of dissolved copper. As described above, in the circuit member 2 and the heat radiating member 5, when the copper content is large, the electric resistance is low and the thermal conductivity is high, respectively, so that the heat radiating characteristics are improved. Characteristics (characteristics for suppressing heat generation and reducing power loss of electronic components mounted on the circuit member 2) can also be improved.

In addition, when the copper content is high, the yield stress is low, and plastic deformation easily occurs when heated. Therefore, the first metal layer 4 and the second metal layer 7 are also made of copper having a content of 90% by mass or more. Is preferred. Further, the first metal layer 4 and the second metal layer 7 are preferably made of any one of oxygen-free copper, tough pitch copper and phosphorous deoxidized copper having a high copper content. Among them, it is preferable that the copper content is 99.995% by mass or more of linear crystalline oxygen-free copper, single-crystal high-purity oxygen-free copper, and vacuum-dissolved copper, and the thickness thereof is, for example, 0.1 mm. It is 0.6 mm or less.

In particular, it is more preferable that the first metal layer 4 has a higher copper content than the circuit member 2 and the second metal layer 7 has a higher copper content than the heat radiating member 5. The adhesion of each of the first metal layer 4 and the circuit member 2, the second metal layer 7 and the heat radiating member 5 is increased, and the reliability can be further increased.

The first bonding layer 3 and the second bonding layer 6 contain silver and copper as main components and contain at least one active metal selected from titanium, zirconium, hafnium, and niobium, and the thickness thereof is supported. It is set to a thickness that can cover protrusions (not indicated when referring to protrusions that are not limited to regions) on the first main surface and the second main surface of the substrate 1. Furthermore, it is more preferable that the first bonding layer 3 and the second metal layer 6 contain one or more selected from molybdenum, tantalum, osmium, rhenium, and tungsten.

In addition, about content of each component of the 1st joining layer 3, the 1st metal layer 4, the 2nd joining layer 6, the 2nd metal layer 7, the

circuit members

2a and 2b, and the

heat radiating members

5a and 5b, It can be determined by fluorescent X-ray analysis or ICP (Inductively Coupled Plasma) emission spectroscopy.

Next, the ceramic sintered body that is the support substrate 1 can use, for example, a nitride whose main component is silicon nitride, aluminum nitride, or the like, or an oxide that is made of aluminum oxide, zirconium oxide, or the like. In particular, the main component of the ceramic sintered body is preferably silicon nitride, aluminum nitride, or aluminum oxide. When the main component is any of these components, these components have high thermal conductivity and excellent mechanical properties, so that heat dissipation properties and reliability can be improved. In addition, the ceramic sintered body may contain a rare earth element oxide, magnesium oxide, calcium oxide, or the like as a sintering aid mainly in order to promote sintering in the firing step.

Further, the mechanical properties of the ceramic sintered body described above are that the three-point bending strength is 750 MPa or more, the dynamic elastic modulus is 300 GPa or more, the Vickers hardness (Hv) is 13 GPa or more, and the fracture toughness (K _1C ) Is preferably 5 MPam ^1/2 or more. Since these mechanical characteristics are in the above range, the circuit board 10 can improve the creep resistance and durability against heat cycle, so that high reliability can be obtained and it can be used for a long time. it can. From such a viewpoint, the ceramic sintered body is preferably composed mainly of silicon nitride.

The three-point bending strength may be measured according to JIS R 1601-2008 (ISO 17565: 2003 (MOD)). However, if the thickness of the ceramic sintered body is thin and the thickness of the test piece cut out from the ceramic sintered body cannot be 3 mm, the thickness of the ceramic sintered body shall be evaluated as it is as the thickness of the test piece. The result preferably satisfies the above numerical value.

Moreover, in order to evaluate the rigidity of the ceramic sintered body, it is sufficient to evaluate using the dynamic elastic modulus. This dynamic elastic modulus conforms to the ultrasonic pulse method defined in JIS R 1602-1995. To measure. However, when the thickness of the ceramic sintered body is thin and the thickness of the test piece cut out from the ceramic sintered body cannot be 10 mm, the evaluation is made using the cantilever resonance method, and the result is the above It is preferable to satisfy the numerical value.

Vickers hardness (Hv) and fracture toughness (K _1C ) conform to the indenter press-in method (IF method) defined in JIS R 1610-2003 (ISO 14705: 2000 (MOD)) and JIS R 1607-1995, respectively. To measure. The thickness of the ceramic sintered body is thin, and the thickness of the test piece cut out from the ceramic sintered body is determined by the indenter press-in method (IF) of JIS R 1610-2003 (ISO 14705: 2000 (MOD)) and JIS R 1607-1995, respectively. When the thickness of the ceramic sintered body cannot be set to 0.5 mm and 3 mm specified in (Method), it is preferable that the thickness of the ceramic sintered body is evaluated as it is as the thickness of the test piece and the result satisfies the above numerical value. However, when the thickness of the ceramic sintered body is so thin that the above-mentioned numerical value cannot be satisfied by evaluating the thickness as it is, for example, when the thickness is 0.2 mm or more and less than 0.5 mm, the test force and indentation load applied to the ceramic sintered body The Vickers hardness (Hv) and the fracture toughness (K _1C ) may be measured by setting the test force and the indentation load time to 15 seconds for both.

Further, the electrical characteristics of the ceramic sintered body as described above, the volume resistivity, a is at normal temperature 10 ¹⁴ Ω · cm or more and 300 ° C. at 10 ¹² Ω · cm or more. The volume resistivity may be measured according to JIS C 2141-1992. However, if the ceramic sintered body is small and the ceramic sintered body cannot be sized in accordance with JIS C 2141-1992, it shall be evaluated using the two-terminal method, and the result satisfies the above numerical values. It is preferable to do.

The three-point bending strength, dynamic elastic modulus, Vickers hardness (H _v ) and fracture toughness (K _1C ) of the support substrate 1 constituting the circuit board 10 are changed from the circuit board 10 to the first bonding layer 3, The two bonding layers 6, the first metal layer 4, the second metal layer 7, and the like may be obtained by the above-described method after being removed by etching.

Further, it is preferable that the ceramic sintered body is composed mainly of silicon nitride, and the protrusions present on the first main surface and the second main surface contain an oxide of aluminum. Since the aluminum oxide can promote liquid phase sintering in the sintering step, the protrusions can be firmly fixed to the support substrate 1 and integrated. In particular, when the aluminum oxide is magnesium aluminate, the corrosion resistance of the protrusions can be increased. Note that the oxide of aluminum contained in the protrusions can be identified using thin film X-ray diffraction or transmission electron microscopy.

Further, in the support substrate 1 made of a ceramic sintered body mainly composed of silicon nitride, it is preferable that the content of the oxide of aluminum is smaller in the support substrate 1 than in the protrusions. When the content of the oxide of aluminum is smaller in the support substrate 1 than in the protrusion, the support is more than in the case where the content of the protrusion and the support substrate 1 is equal or the content of the support substrate 1 is higher. Since the propagation of phonons between the grain boundary phase existing between the crystals forming the substrate 1 and the crystals easily proceeds, the heat conduction between both main surfaces of the support substrate 1 is promoted. Furthermore, if there are few glass (amorphous) components which comprise the grain boundary phase which exists between the crystals which form the support substrate 1, the dielectric breakdown voltage of the support substrate 1 will become high, and the reliability with respect to insulation performance will be made high. Can do.

In particular, the content of the oxide of aluminum in the support substrate 1 is more preferably 0.1% by mass or less. The aluminum oxide content can be determined by ICP emission spectroscopic analysis. Specifically, first, an aluminum oxide was identified using thin film X-ray diffraction or transmission electron microscopy, and the content of aluminum, which is a metal element determined by ICP emission spectroscopy, was identified. It can obtain | require by converting into content of the oxide of aluminum according to a composition formula.

7A and 7B show an example of the electronic device of the present embodiment, in which FIG. 7A is a plan view, FIG. 7B is a cross-sectional view taken along the line QQ ′ of FIG. 7A, and FIG. It is. The electronic device S of the example shown in FIG. 7 is one in which electronic components 8 and 9 such as one or more semiconductor elements are mounted on the circuit member 2 of the circuit board 10 of the present embodiment. , 9 are electrically connected to each other by a conductor (not shown). According to the electronic device S of the present embodiment, since the electronic components 8 and 9 are mounted on the circuit member 2 in the circuit board 10 of the present embodiment, dielectric breakdown is unlikely to occur between the circuit members 2 and between the heat dissipation members 5. In addition to being excellent in heat dissipation characteristics when the electronic components 8 and 9 are activated, the circuit member 2 and the heat dissipation member 5 are firmly bonded to the support substrate 1, so that the highly reliable electronic device S is provided. Can do.

The circuit member 2 and the heat radiating member 5 are preferably arranged in a plurality of rows and a plurality of columns, respectively, in plan view, as in the example shown in FIG. As described above, when the circuit member 2 and the heat radiating member 5 are arranged in a plurality of rows and columns in a plan view, the stress generated in the support substrate 1 when the circuit member 2 and the heat radiating member 5 are joined to the support substrate 1. Since it becomes easy to disperse | distribute, the curvature of the support substrate 1 can be suppressed.

Next, a case where the main component of the ceramic sintered body forming the support substrate is silicon nitride will be described as an example of the circuit board manufacturing method of the present embodiment. First, a silicon nitride powder having a β conversion rate of 20% or less, a powder of at least one of magnesium oxide (MgO) and calcium oxide (CaO) as a sintering aid, and a rare earth element oxide powder are placed. After quantitative weighing, wet mixing using a barrel mill, rotary mill, vibration mill, bead mill, sand mill, agitator mill, etc., and pulverizing the organic binder such as paraffin wax, polyvinyl alcohol (PVA), polyethylene glycol (PEG), etc. In addition, a slurry is obtained.

Here, the additive amount of the sintering aid powder is a powder of magnesium oxide (MgO) as a sintering aid out of a total of 100 mass% of the silicon nitride powder and the total of these sintering aid powders. In addition, the total of the powders of calcium oxide (CaO) may be 2% by mass to 7% by mass, and the rare earth element oxide powder may be 7% by mass to 14% by mass.

A ball used for pulverizing silicon nitride and a sintering aid is preferably a ball made of a material in which impurities are hardly mixed or a silicon nitride sintered body having the same material composition. Silicon nitride and sintering aid are pulverized until the particle size (D ₉₀ ) is ₉₀ μm or less when the total volume of the particle distribution curve is 100%. Is preferable from the viewpoint of improving the sinterability and columnar or acicular formation of the crystal structure. The particle size distribution obtained by grinding can be adjusted by the outer diameter of the ball, the amount of the ball, the viscosity of the slurry, the grinding time, and the like. In order to reduce the viscosity of the slurry, it is preferable to add a dispersant, and in order to pulverize in a short time, it is preferable to use a powder having a particle size (D ₅₀ ) of 1 μm or less with a cumulative volume of 50% in advance.

Next, the obtained slurry is passed through a sieve having a particle size number smaller than 200 mesh described in ASTM E 11-61, and then dried to produce granules containing silicon nitride as a main component (hereinafter referred to as silicon nitride material). Called granules). Drying may be performed by a spray dryer, and there is no problem even if other methods are used. And, by using a powder rolling method using a pair of rolls arranged with a predetermined gap and rotating in opposite directions, granules containing silicon nitride as a main component are formed into a sheet to form a ceramic green sheet, The ceramic green sheet is cut into a predetermined length to obtain a molded body mainly composed of silicon nitride.

Next, a granular material such as granules or bedding powder is placed on the main surface of the molded body mainly composed of silicon nitride. The method of mounting may be sprinkled using a sieve or the like, or added to a slurry by adding a solvent or the like to the powder and applied using a brush or a roller. The powder constituting the granular material is, for example, at least one of silicon powder, silicon nitride powder, silicon oxide powder, and sialon powder, and includes magnesium oxide (MgO) and calcium oxide (CaO). Further, it may contain an oxide of a rare earth element. The granule is, for example, the above powder mixed and pulverized into a slurry and dried with a spray dryer, and the bed powder is a pulverized sintered body baked using the above powder. is there. In addition, in order to set the density of the protrusions 1a ₂ to be placed in the circuit member arrangement region to 48 pieces / cm ² or more and 502 pieces / cm ² or less, the density of the powder particles is 31 pieces / cm ² or more and 321 pieces / cm ^2. What is necessary is as follows.

In order to make the average height of the protrusions 1a ₁ existing in the inter-circuit member region lower than the average height of the protrusions 1a ₂ existing in the circuit member disposition region, the inter-circuit member region and the circuit member disposition region What is necessary is just to vary the magnitude | size of the granular material to mount.

Next, a plurality of compacts mainly composed of silicon nitride having powder particles placed on the first main surface are stacked and placed in a firing furnace in this state and fired. In order to suppress volatilization of the components contained in the silicon nitride-based molded body, a co-material containing components such as magnesium oxide and rare earth element oxide may be disposed in the firing furnace. Regarding the temperature, the temperature was raised from room temperature to 300 to 1000 ° C in a vacuum atmosphere, and then nitrogen gas was introduced to maintain the nitrogen partial pressure at 15 to 300 kPa, and the temperature in the firing furnace was further increased. By holding at a temperature of 1700 ° C. or higher and lower than 1800 ° C. for 4 hours or longer and 10 hours or shorter, it is possible to obtain the support substrate 1 constituting the circuit board 10 of the present embodiment whose main component is silicon nitride. According to the above-described method, the protrusion 1a existing on the first main surface is integrated, and a needle is formed from a part of the raised portion 1b of the protrusion 1a by the growth of crystal grains mainly composed of silicon nitride. A plurality of columnar crystals 1c or columnar crystals 1d extend.

Further, by stacking a plurality of compacts mainly composed of silicon nitride on which powder particles are placed on the second main surface and firing in the same manner as described above, the second main surface is the same as the first main surface. In addition, a large number of raised portions 1f containing silicon are integrated, and a plurality of needle-like crystals 1h or columnar crystals 1g are extended from a part of the raised portions 1f by growth of crystal grains mainly composed of silicon nitride. The support substrate 1 which comprises the circuit board 10 of this embodiment which has silicon as a main component can be obtained. In addition, in order to set the density of the protrusions 1e ₂ placed in the heat dissipating member arrangement region to 48 pieces / cm ² or more and 502 pieces / cm ² or less, the density of the powder particles is 31 pieces / cm ² or more and 321 pieces / cm ^2. What is necessary is as follows.

Next, the case where the main component of the ceramic sintered body forming the support substrate is aluminum nitride will be described as another example of the circuit board manufacturing method of the present embodiment. First, after weighing a predetermined amount of aluminum nitride powder and rare earth element oxide powder as a sintering aid, wet mixing using a barrel mill, a rotating mill, a vibration mill, a bead mill, a sand mill, an agitator mill, etc., An organic binder such as polyvinyl butyral (PVB) is added to obtain a slurry. It should be noted that the amount of the sintering aid powder added here is 1% by mass or more and 3% by mass or less in the total of 100% by mass of the aluminum nitride powder and the sintering aid powder. Good.

Next, after passing the obtained slurry through a sieve having a particle size number smaller than 200 mesh described in ASTM E 11-61, the slurry is formed into a sheet using a doctor blade method, and then ceramic. A green sheet is obtained, and the ceramic green sheet is cut into a predetermined length to obtain a molded body mainly composed of aluminum nitride.

Next, a large number of powder particles such as granules containing aluminum or bed powder are placed on the main surface of the molded body mainly composed of aluminum nitride. The method of mounting may be sprinkled using a sieve or the like, or added to a slurry by adding a solvent or the like to the powder and applied using a brush or a roller. The powder constituting the granular material is, for example, at least one of an aluminum powder, an aluminum nitride powder, and an aluminum oxide powder, and may contain a rare earth element oxide.

Next, a plurality of compacts mainly composed of aluminum nitride on which powder particles are placed on the first main surface are stacked, and placed in a firing furnace in this state and fired. Regarding the temperature, first, after degreasing in a nitrogen or argon atmosphere at a temperature of 600 ° C. to 850 ° C., the temperature is raised and held at a temperature of 1300 ° C. to 1500 ° C. for 2 hours to 5 hours. Then, the temperature is further raised and maintained at a temperature of 1780 ° C. or more and 1820 ° C. or less for 2 hours or more and 5 hours or less, thereby obtaining the support substrate 1 constituting the circuit board 10 of the present embodiment mainly composed of aluminum nitride. be able to. In addition, what is necessary is just to make the pressure in the baking in a baking furnace into 100 kPa or more and 10 MPa or less, for example.

In order to obtain the support substrate 1 in which the kurtosis (R _ku ) of the first main surface of the support substrate 1 is 2 or more and the skewness (R _sk ) is 1 or less, the first main surface side used in the powder rolling method is used. A roll having a kurtosis (R _ku ) of 2.5 or more and a skewness (R _sk ) of 1.5 or less may be used. The same applies to the second main surface.

Then, in order to obtain the circuit board 10 of the present embodiment of the example shown in FIG. 4, for example, titanium, zirconium, etc. on the first main surface and the second main surface of the support substrate 1 constituting the circuit board 10 of the present embodiment. A silver (Ag) -copper (Cu) alloy paste-like brazing material containing at least one active metal selected from hafnium and niobium, any one of a screen printing method, a roll coater method, a brush coating method, etc. Apply with. The pasty brazing material may contain one or more selected from molybdenum, tantalum, osmium, rhenium and tungsten.

Next, the circuit member 2 containing copper as a main component is disposed on the brazing material to be the first bonding layer 3, and the heat dissipating member 5 having copper as the main component is disposed on the brazing material to be the second bonding layer 6. . Thereafter, the brazing material applied to the first main surface and the second main surface of the support substrate 1 by heating at a temperature of 800 ° C. or higher and 900 ° C. or lower becomes the first bonding layer 3 and the second bonding layer 6, respectively. Thus, the circuit member 2 and the heat dissipation member 5 are bonded to the support substrate 1 via the first bonding layer 3 and the second bonding layer 6, respectively. And thereby, the circuit board 10 of this embodiment of the example shown in FIG. 4 can be obtained.

In addition, when using the substrate-like sintered body produced by placing the same size powder particles on the main surface of the molded body in the placement of the powder particles, the following method is also used between the circuit members. The average height of the protrusions 1a ₁ existing in the region can be made lower than the average height of the protrusions 1a ₂ existing in the circuit member arrangement region. Using this substrate-like sintered body, the circuit member 2 is bonded to the first main surface via the first bonding layer 3 and the second main surface via the second bonding layer 6 by the method described above. After the heat radiating member 5 is bonded to the surface, a resist having acid resistance is applied to each main surface of the circuit member 2 and the heat radiating member 5 opposite to the bonding surface by using a screen printing method or a roll coater method, and dried. After the resist is dried, both the first main surface side and the second main surface side of the support substrate 1 are etched using a mixed solution of sulfuric acid and hydrogen peroxide solution, a cupric chloride solution or a ferric chloride solution. To do. Then, after etching, the resist may be peeled off using a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution or a mixed solution thereof heated to 40 ° C. or higher and 90 ° C. or lower.

In order to obtain the circuit board 10 of the embodiment of the example shown in FIG. 6, first, on both main surfaces of the support substrate 1 constituting the circuit board 10 of the embodiment, titanium, zirconium, hafnium and niobium are used. A silver (Ag) -copper (Cu) alloy paste brazing material containing at least one selected active metal is applied by any one of a screen printing method, a roll coater method and a brush coating method. Next, a thin intermediate material mainly composed of copper, which becomes the first metal layer 4 and the second metal layer 7, is disposed on the brazing material applied to each main surface. Then, the brazing material applied to the first main surface and the second main surface of the support substrate 1 becomes the first bonding layer 3 and the second bonding layer 6 by heating at 800 ° C. or more and 900 ° C. or less, respectively. .

Next, a thin intermediate material to be the first metal layer 4 on the first bonding layer 3 and a thin intermediate material to be the second metal layer 7 on the second bonding layer 6 are respectively connected to the circuit. The surface facing the member 2 and the heat radiating member 5 is polished. And the circuit member 2 which has copper as a main component on the 1st main surface side, and the thermal radiation member 5 which has copper as a main component on the 2nd main surface side are arrange | positioned, and it selects from hydrogen, nitrogen, neon, or argon In the atmosphere, heating is performed at 300 ° C. or more and 500 ° C. or less, and a pressure of 30 MPa or more is applied to the first main surface of the support substrate 1 through the first bonding layer 3 and the first metal layer 4 in order. The member 2 can be bonded, and the heat radiating member 5 can be bonded to the second main surface of the support substrate 1 through the second bonding layer 6 and the second metal layer 7 in order, The circuit board 10 of this embodiment of the example shown in FIG. 6 can be obtained.

And by mounting the electronic components 8 and 9 on the circuit member 2 in the circuit board 10 of this embodiment, the electronic device S of this embodiment can be obtained.

Hereinafter, examples of the present invention will be described in detail, but the present invention is not limited to these examples.

First, silicon nitride powder having a β conversion rate of 10% (that is, an α conversion rate of 90%), magnesium oxide (MgO) powder, and erbium oxide (Er ₂ O ₃ ) powder as a sintering aid These were mixed and pulverized wet using a rotary mill until the particle size (D ₉₀ ) was 1 μm or less, and an organic binder was added to form a slurry. Here, out of 100% by mass of the total sum of the silicon nitride powder and these sintering aids, the magnesium oxide (MgO) powder and the erbium oxide (Er ₂ O ₃ ) powder were 5% by mass, 10% by mass.

Next, the obtained slurry was passed through a mesh sieve having a particle size number of 250 described in ASTM E 11-61 and then dried using a spray dryer to obtain silicon nitride granules. And the silicon nitride granule was shape | molded in the sheet form using the powder rolling method, and it was set as the ceramic green sheet, and the silicon nitride type molded object which cut | disconnected this ceramic green sheet to predetermined length was obtained.

Next, a granule, which is a powder body containing silicon nitride as a main component and magnesium oxide (MgO) and erbium oxide (Er ₂ O ₃ ) as a sintering aid, was obtained by the same method as described above. In the production of this granule, the amount of magnesium oxide (MgO) powder and erbium oxide (Er ₂ O ₃ ) powder added was 100% by mass of the total sum of the silicon nitride powder and these sintering aids. , 5% by mass and 10% by mass, respectively.

The average height of the protrusions 1a ₂ in the supporting substrate with a granular material, which becomes the value shown in Table 1, was placed a granular material on the first major surface of the silicon nitride molded body.

Next, a plurality of silicon nitride molded bodies on which powder particles were placed on the first main surface were stacked for each sample, and placed in a firing furnace in this state and fired. In the firing furnace, a co-material containing magnesium oxide (MgO) and erbium oxide (Er ₂ O ₃ ) was disposed in order to suppress volatilization of the components contained in the silicon nitride-based molded body. About temperature, it heated up in the vacuum atmosphere from room temperature to 500 degreeC, Then, nitrogen gas was introduce | transduced and nitrogen partial pressure was maintained at 30 kPa. Then, the temperature in the firing furnace is further increased, and the temperature is set to 1750 ° C. and held for the time shown in Table 1 to obtain a silicon nitride substrate having a length of 60 mm, a width of 30 mm, and a thickness of 0.32 mm. It was.

Next, using the obtained silicon nitride substrate, as shown in FIG. 2, a paste-like brazing material is applied by screen printing to the portion where the

circuit members

2a and 2b on the first main surface are arranged. And dried at 135 ° C.

Here, the brazing material to be applied is a brazing material containing silver and copper as main components and titanium, molybdenum and tin as additive components, and each content of silver, copper, titanium, molybdenum and tin is 48.2% by mass. 37.1 mass%, 2.3 mass%, 10.0 mass%, and 2.4 mass%.

Then, the

circuit members

2a and 2b made of oxygen-free copper are arranged as shown in FIG. 2 so as to be in contact with the brazing material, and are pressure bonded at a pressure of 30 MPa or more in a state maintained at 840 ° C. in a vacuum atmosphere. . Then, after the pressure bonding, the

circuit members

2 a and 2 b were bonded via the first bonding layer 3 by cooling to 50 ° C., which is a temperature at which copper is not oxidized in a pressurized state, and taking out.

Then, a resist having acid resistance was applied to each main surface of the

circuit members

2a and 2b on the side opposite to the bonding surface by a screen printing method and dried. Next, etching was performed using a cupric chloride solution. Then, after etching, the resist is peeled off using a sodium hydroxide aqueous solution heated to 70 ° C. 1-3 were obtained. The specific gravity and temperature of the ferric chloride solution were 1.45 and 45 ° C., respectively, and the etching time was as shown in Table 1.

Sample No. An intermediate material made of oxygen-free copper and serving as the first metal layer 4 is in contact with this brazing material by using 1 to 3 and a brazing material applied in the same process until drying. And heated at 840 ° C. in a vacuum atmosphere. Next, after polishing the surface facing the

circuit members

2a and 2b of the intermediate material to be the first metal layer 4, the

circuit members

2a and 2b are arranged and kept at 400 ° C. in a hydrogen atmosphere. And pressure bonding at a pressure of 30 MPa or more. Then, after the pressure bonding, the

circuit members

2a and 2b were bonded through the first bonding layer 3 and the first metal layer 4 in order by cooling to 50 ° C. in the pressurized state and taking out.

Etching is performed by the same method as described above, and the sample No. which is the circuit board 10 is checked. 4-6 were obtained.

In addition, as a comparative example, sample No. 1 was used except that no etching was performed using a granular material in which the average height of the protrusions 1a _{2 on} the support substrate was a value shown in Table 1. Using the same method as that used to obtain 1-3, sample no. 7, 8 were obtained.

Here, sample no. The

circuit members

2a and 2b constituting 1 to 8 each have a square shape with a side of 24 mm, a thickness of 2 mm, and the distance between the circuit member 2a and the circuit member 2b is 2 mm. Further, the

first bonding layers

3a and 3b have shapes matched to the

circuit members

2a and 2b, respectively, and have a thickness of 0.025 mm. Sample No. The first metal layer 4 constituting 4 to 6 was shaped to match the

circuit members

2a and 2b, and the thickness was 0.35 mm.

Then, an AC voltage is applied between the

circuit members

2a and 2b, a voltage when the insulation breaks between the

circuit members

2a and 2b (hereinafter referred to as a dielectric breakdown voltage) is measured by a withstand voltage tester, and the measured insulation is measured. The breakdown voltage values are shown in Table 1.

Further, the bonding strength between the circuit member 2a and the support substrate 1 was evaluated by measuring the peel strength (kN / m) of the circuit member 2a in accordance with JIS C 6481-1996. The evaluation of the bonding strength was performed by measuring the peeling strength of the circuit member 2a, and the values are shown in Table 1. The sample for measuring the peel strength was measured by removing both sides in the X direction of the square circuit member 2a having a side of 24 mm by etching to 10 mm × 24 mm.

And each sample was hold | maintained for 5 minutes at the temperature of 260 degreeC in nitrogen gas atmosphere. Next, using a stylus surface roughness meter in conformity with JIS B 0601-2001 (ISO 4287-1997), the maximum height R _Z of the longitudinal direction of the supporting substrate is measured, the warpage this measurement Value. The measurement length, cut-off value, stylus tip radius, and stylus scanning speed were 55 mm, R + W, 2 μm, and 1 mm / second, respectively, and the measured warpage values are shown in Table 1.

After the calculation of the average height of the protrusions 1a _1, 1a ₂ in the support substrate 1 of each sample, first, embedded in a resin from the supporting substrate 1 respectively by cutting the portion including the projections 1a _1, 1a _2, The fracture surface was polished by a cross section polisher to produce polished surfaces including protrusions 1a ₁ and 1a ₂ respectively. Specifically, using a scanning electron microscope sample preparation device (cross-section polisher, SM-09010 manufactured by JEOL Ltd.), the acceleration voltage of the irradiated argon ions is 6 kV, and the maximum current of the detected argon ions is maximum. The argon gas flow rate was adjusted to 70 to 80% of the value, and the polishing time was 8 hours. Next, using an optical microscope, the magnification E was set to 800 times, and the heights E and F of the ten protrusions 1a ₁ and 1a _{2 on} the polished surface were measured, and the calculated average heights are shown in Table 1. .

As shown in Table 1, Sample No. 1 to 6 are configured such that the average height of the protrusions 1a ₁ existing in the inter-circuit member region is lower than the average height of the protrusions 1a ₂ existing in the circuit member disposition region. It has been found that the support substrate 1 and the circuit member 2 can be firmly joined.

Further, in order to confirm the heat dissipation characteristics due to the presence of the protrusions 1a _{1 in the} area between the circuit members, a support substrate having no protrusions was prepared. A circuit board was produced using the brazing material and circuit members used in the production of 1-3. And sample no. After mounting the semiconductor elements on the

circuit members

2a and 2b of the sample having no protrusions 1 and the region between the circuit members, a current of 30 A was passed. Five minutes after the current was passed, the temperature at the surface of each semiconductor element was measured by thermography, and the average value of the temperatures was compared. As a result, the sample having no protrusions in the region between the circuit members was 76 ° C. In contrast, sample no. 1 was 72 ° C., and it was found that the heat dissipation characteristics can be improved by the presence of the protrusion 1a _{1 in the} region between the circuit members.

Sample No. In Nos. 4 to 6, since the first metal layer 4 containing copper as a main component is disposed between the first bonding layer 3 and the circuit member 2, the diffusion of copper causes a lower temperature. Since the support substrate 1 and the circuit member 2 are joined, the curvature which arises in the support substrate 1 at the time of joining is suppressed. From this result, it was found that the thicker circuit member 2 can be used and the heat dissipation characteristics can be improved.

Sample No. In the same manufacturing method as that of No. 1, a sample using the support substrate 1 having a kurtosis (R _ku ) of the first main surface of 2 or more and a skewness (R _sk ) of 1 or less was obtained. It was found that the bonding strength was improved by about 5%.

Sample No. 1 prepared in Example 1 was used. In addition to the configurations 1 to 8, a sample in which the heat dissipating member 5 was arranged on the second main surface was produced. Therefore, the description on the first main surface side is omitted. First, a silicon nitride-based molded body was produced by the same method as in Example 1. The average height of the projections 1e ₂ in the support substrate 1 by using the powdery grains of the values shown in Table 2, placing the powder or granular material to the second major surface of the silicon nitride molded body.

And the silicon nitride board | substrate was obtained by baking by the method similar to Example 1. FIG. Next, sample No. For Samples 9 to 11, the sample Nos. Of Example 1 were prepared so as to have the configuration shown in FIG. The heat radiating member 2 was joined by the same method as the joining method of the circuit member 2 in 1 to 3, and then etched. Sample No. Samples Nos. 12 to 14 in Example 1 were prepared so as to have the configuration shown in FIG. The heat dissipating member 2 was joined by the same method as the joining method of the circuit member 2 in 4 to 6, followed by etching.

As a comparative example, sample No. For sample No. 15, sample no. The heat radiating member 2 was joined by the same method as the circuit member 2 joining method in FIG. Sample No. For sample 16, sample no. The heat radiating member 2 was joined by the same method as the circuit member 2 joining method in FIG.

Here, sample no. The

heat dissipating members

5a and 5b constituting 9 to 16 each have a square shape with a side of 26 mm, a thickness of 2 mm, and the distance between the heat dissipating member 5a and the heat dissipating member 5b was 2 mm. Further, the second bonding layers 6a and 6b have shapes matched to the

heat dissipation members

5a and 5b, respectively, and have a thickness of 0.025 mm. Sample No. The second metal layer 7 constituting 12 to 14 was shaped to match the

heat dissipating members

5a and 5b, and the thickness was 0.35 mm.

And the dielectric breakdown voltage between the

thermal radiation members

5a and 5b was measured by the method similar to Example 1. FIG. Further, the peel strength (kN / m) was measured. The sample for measuring the peel strength was measured as 10 mm × 26 mm by removing both sides in the X direction of the square heat radiation member 5a having a side of 26 mm by etching. Further, in the same manner as in Example 1, the maximum height R _Z of the longitudinal direction of the supporting substrate 1 was measured and the measured value to the value of warpage. It was also calculated by measuring the respective average height of the projections 1e _1, 1e ₂ in the heat dissipation member 5 of each sample in the same manner as in Example 1. The results are shown in Table 2.

As shown in Table 2, Sample No. Nos. 9 to 14 have a structure in which the average height of the protrusions 1e ₁ existing in the region between the heat dissipating members is lower than the average height of the protrusions 1e ₂ existing in the heat dissipating member disposition region. It was found that the support substrate 1 and the heat dissipating member 5 can be firmly joined.

Sample No. In Nos. 12 to 14, since the second metal layer 7 containing copper as a main component is disposed between the second bonding layer 6 and the heat radiating member 5, the diffusion of copper causes a lower temperature. Since the support substrate 1 and the heat radiating member 5 are joined, the curvature produced in the support substrate 1 at the time of joining is suppressed. From this result, it was found that a thicker heat radiating member 5 can be used and the heat radiating characteristics can be improved.

Next, the thermal conductivity and the three-point bending strength due to the difference in the main components of the support substrate 1 were confirmed. A support substrate 1 made of ceramics mainly composed of aluminum oxide, silicon nitride, aluminum nitride, and zirconium oxide is manufactured, and conforms to JIS R 1611-1997 and JIS R 1601-2008 (ISO 17565: 2003 (MOD)). The thermal conductivity and three-point bending strength of each sample were measured. These measured values are shown in Table 3.

As shown in Table 3, sample No. In Nos. 17 to 19, since the support substrate 1 is made of ceramics mainly composed of aluminum oxide, silicon nitride, and aluminum nitride, the thermal conductivity is 34 W / (m · K) or more, and the three-point bending strength is 310 MPa or more. It was found that the thermal and mechanical characteristics required for the support substrate 1 of the circuit board 10 were satisfied.

From the above results, the circuit board 10 of the present embodiment is less likely to cause dielectric breakdown between the circuit members 2 and has excellent heat dissipation characteristics, and the circuit member 2 and the support substrate 1 are firmly bonded. Thus, it was found that an electronic device in which an electronic component is mounted on the circuit member 2 in the circuit board 10 can be an excellent electronic device with high reliability.

1: support substrate 1a, 1e:

protrusion

1b, 1f: raised portion 1c, 1g: acicular crystal 1d, 1h: columnar crystal 2: circuit member 3: first bonding layer 4: first metal layer 5: heat dissipation member 6: Second bonding layer 7: Second metal layer 8, 9: Electronic component
10: Circuit board S: Electronic device

Claims

A plurality of circuit members are joined and arranged on a first main surface of a support substrate made of a ceramic sintered body via a first joining layer, and between the circuit member arrangement region and the circuit members on the first main surface. A circuit board, wherein protrusions are present in the region, and an average height of the protrusions existing in the inter-circuit member region is lower than an average height of the protrusions existing in the circuit member arrangement region.
The circuit member is mainly composed of copper, and a first metal layer mainly composed of copper is disposed between the first bonding layer and the circuit member. Circuit board as described.
3. The circuit board according to claim 1, wherein a kurtosis (R ku ) of the first main surface of the support substrate is 2 or more and a skewness (R sk ) is 1 or less.
A plurality of heat dissipating members are disposed on a second main surface that is opposite to the first main surface of the support substrate via a second bonding layer, and the heat dissipating members are disposed on the second main surface. 2. A protrusion is present in the region and the region between the heat radiating members, and an average height of the protrusion existing in the region between the heat radiating members is lower than an average height of the protrusion existing in the heat radiating member arrangement region. The circuit board according to claim 3.
The heat dissipation member is composed mainly of copper, and a second metal layer composed mainly of copper is disposed between the second bonding layer and the heat dissipation member. Circuit board as described.
6. The circuit board according to claim 4, wherein kurtosis (R ku ) of the second main surface of the support substrate is 2 or more and skewness (R sk ) is 1 or less. 6.
7. The circuit board according to claim 1, wherein the ceramic sintered body is mainly composed of aluminum oxide, silicon nitride, or aluminum nitride.
An electronic device comprising an electronic component mounted on the circuit member in the circuit board according to any one of claims 1 to 7.