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WO2020179893A1 - Circuit board production method - Google Patents

Circuit board production method Download PDF

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Publication number
WO2020179893A1
WO2020179893A1 PCT/JP2020/009546 JP2020009546W WO2020179893A1 WO 2020179893 A1 WO2020179893 A1 WO 2020179893A1 JP 2020009546 W JP2020009546 W JP 2020009546W WO 2020179893 A1 WO2020179893 A1 WO 2020179893A1
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WO
WIPO (PCT)
Prior art keywords
substrate
circuit board
layer
metal plate
metal layer
Prior art date
Application number
PCT/JP2020/009546
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French (fr)
Japanese (ja)
Inventor
栄樹 津島
Original Assignee
株式会社Ｆｊコンポジット
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Publication date
Application filed by 株式会社Ｆｊコンポジット filed Critical 株式会社Ｆｊコンポジット
Publication of WO2020179893A1 publication Critical patent/WO2020179893A1/en

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    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B37/00—Joining burned ceramic articles with other burned ceramic articles or other articles by heating
    • C04B37/02—Joining burned ceramic articles with other burned ceramic articles or other articles by heating with metallic articles
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/09—Use of materials for the conductive, e.g. metallic pattern
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/38—Improvement of the adhesion between the insulating substrate and the metal

Definitions

  • the present invention relates to a method for manufacturing a circuit board in which a metal plate containing copper as a main component is bonded to an insulating substrate.
  • Power semiconductor elements that operate with a large current are mounted on a circuit board and used.
  • a metal plate that serves as a wiring pattern is bonded onto an insulating substrate that is insulating and has high mechanical strength. Consists of The metal plate is also used for heat dissipation during operation of the mounted power semiconductor element.
  • ceramic materials such as alumina, aluminum nitride, and silicon nitride, which have high insulation and mechanical strength, are used as the material for the insulating substrate.
  • a material constituting the metal plate copper or an alloy thereof having high conductivity and thermal conductivity is used.
  • the thermal expansion coefficient of the material forming the insulating substrate and the material forming the metal plate are greatly different from each other, during the cooling/heating cycle, the circuit board is deformed or warped due to the difference in thermal expansion. Therefore, the metal plate may be peeled off from the insulating substrate. Therefore, it is required that the bonding strength between the metal plate and the insulating substrate in the circuit board is high.
  • a brazing material is used to bond such different substances with high bonding strength.
  • a brazing material paste in which a binder (organic material) and metal particles constituting the brazing material are mixed is applied onto the substrate, the brazing material is melted, and then solidified between the metal plate and the insulating substrate. The joining is performed by.
  • the type of brazing material metal material constituting the brazing material
  • a metal made of copper is not particularly provided with a layer for joining a brazing material or the like for joining between the metal plate and the insulating substrate as described above.
  • a direct bonding method direct bonding copper: DBC
  • DBC direct bonding copper
  • a metal plate made of copper and a ceramic substrate are brought into close contact with each other to a predetermined high temperature, so that the copper constituting the metal plate and oxygen slightly contained in the metal plate are co-crystal liquid phases. And the liquid phase acts like a braze for bonding.
  • the thickness of the bonding layer is substantially negligible, and the insulating substrate and the metal plate are substantially directly bonded.
  • This joining method is particularly effective when the ceramic substrate is an oxide such as alumina.
  • an insulating substrate ceramic substrate
  • a nitride-based (aluminum nitride, silicon nitride, etc.) ceramic material having a higher thermal conductivity has been widely used. There is. In such a nitride-based ceramic substrate, the wettability of the eutectic liquid phase on the surface is low, and thus it is difficult to obtain uniform high bonding strength with DBC.
  • Patent Document 2 describes a technique for joining a metal plate and a ceramic substrate using an active metal brazing material containing Ti, which is an active metal.
  • TiN formed from Ti contributes to the bonding.
  • the active metal brazing material contains Ag and Cu, and the bonding layer after melting and solidification is mainly composed of an Ag—Cu alloy.
  • DBC there is substantially no bonding layer, whereas in this case, such a bonding layer is formed between the metal plate and the ceramic substrate.
  • Ti is preferentially diffused to the side of the ceramic substrate to form TiN, and then the above-mentioned joining layer is formed, so that uniform bonding is achieved. A bond is obtained. Therefore, unlike DBC, when such an active metal brazing material is used, strong bonding can be performed even on a nitride-based ceramic substrate.
  • the thermal conductivity of the bonded layer (alloy layer) formed in this way is generally lower than that of a metal plate or the like. Therefore, in order to obtain sufficient heat dissipation characteristics as a circuit board, it is necessary to make the bonding layer sufficiently thin. On the other hand, when the above-mentioned active metal brazing material (brazing material) is used, it is difficult to make the bonding layer sufficiently thin, so that it is difficult to increase the heat dissipation efficiency.
  • the mechanical strength of the bonding layer itself may not always be sufficient, and the bonding layer itself may break during the thermal cycle. For this reason, the durability of the circuit board using the active metal brazing material against the cooling and heating cycle was not sufficient.
  • the metal plate may be made sufficiently thick.
  • DBC Density Polyethylene
  • the present invention has been made in view of such problems, and an object of the present invention is to provide an invention that solves the above problems.
  • the present invention has the following configurations in order to solve the above problems.
  • the method for manufacturing a circuit board of the present invention is a method for manufacturing a circuit board having a structure in which a metal plate made of copper (Cu) or a copper alloy is bonded to the surface of an insulating substrate.
  • the substrate and the metal plate are laminated in a form between the metal plate and the substrate and the metal plate in a non-oxidizing atmosphere at a temperature at which a reaction occurs between the reaction metal layer and the metal plate and the substrate. It is characterized by comprising a hot pressing step of applying pressure between metal plates.
  • the reactive metal layer contains titanium (Ti).
  • Ti titanium
  • the method of manufacturing a circuit board according to the present invention is characterized in that the thickness of the reaction metal layer is set in the range of 0.01 to 1 ⁇ m.
  • the circuit board manufacturing method of the present invention is characterized in that the substrate is made of a material containing any one of alumina, silicon nitride, aluminum nitride, and beryllium as a main component.
  • the method for manufacturing a circuit board of the present invention is characterized in that the hot pressing step is performed at a temperature of 600° C. or higher and a pressure of 1 MPa or higher.
  • the method for producing a circuit board of the present invention is characterized in that, in the reaction metal layer forming step, an antioxidant layer made of a material different from the reaction metal layer is formed on the reaction metal layer. ..
  • the antioxidant layer contains any one of gold (Au), silver (Ag), copper (Cu), tin (Sn), platinum (Pt), and aluminum (Al). Is characterized by.
  • the circuit board manufacturing method of the present invention is characterized in that the reactive metal layer film forming step is performed by a sputtering method.
  • the method for manufacturing a circuit board of the present invention is characterized in that, in the hot pressing step, the metal plate is pressurized via a spacer, and the spacer is composed of any of a carbon plate, a heat-resistant glass plate, and a ceramic plate.
  • the present invention is configured as described above, it is possible to obtain a high bonding strength between the metal plate and the substrate while thinning the bonding layer formed between the metal plate and the substrate in the circuit board. it can.
  • FIG. 1A to 1F are process cross-sectional views showing an outline of this manufacturing method.
  • the circuit board manufactured here is configured by bonding the metal plate 20 to the surface (the upper surface in FIG. 1A etc.) of the insulating board 10.
  • the substrate 10 shown in FIG. 1A is formed by oxidizing nitride-based ceramics such as silicon nitride (SiN) and aluminum nitride (AlN), and oxidation of alumina (aluminum oxide: Al 2 O 3 ), beryllium oxide (beryllium oxide: BeO), and the like. It is composed of an insulating ceramic material whose main component is physical ceramics.
  • a power semiconductor element that operates at high power can be mounted on the material and used preferably.
  • nitride-based ceramics such as silicon nitride has a higher thermal conductivity than oxide-based ceramics, the heat dissipation efficiency of the circuit board using the same can be increased.
  • a metal plate 20 used as a wiring for a power semiconductor element and a heat sink is bonded onto the substrate 10.
  • the metal plate 20 is made of copper (Cu) or a copper alloy.
  • FIGS. 1A to 1F a process until the metal plate 20 is joined to the substrate 10 is shown.
  • the thickness of the substrate 10 is, for example, several hundred ⁇ m or more, and the size (length and width) is about 100 mm, and a ceramic substrate made of the above materials can be used as the substrate 10.
  • the reaction metal layer 11 is composed of a material that forms the substrate 10 and a material that forms the metal plate 20 (Cu) at a high temperature, and a metal that forms a reaction layer or an alloy.
  • a material that forms the substrate 10 for example, titanium (Ti) is used. Is used. Ti forms an alloy with Cu in the substrate 20, and forms TiN as a compound when the substrate 10 is a nitride-based material, and TiO as a compound when the substrate 10 is an oxide-based material. It can be used particularly preferably.
  • the reaction metal layer 11 is formed by, for example, a sputtering method, and its thickness is formed to be significantly thinner than that of the substrate 10, the metal plate 20, and the brazing material (active metal brazing material) applied and used.
  • the thickness is, for example, in the range of 0.01 ⁇ m to 10 ⁇ m.
  • the reactive metal layer 11 is used only for reacting with the substrate 10 and the metal plate 20 to form a bonding layer, and is preferably thin in order to thin the bonding layer.
  • a vacuum deposition method may be used as another method capable of forming a thin film without oxidizing the reactive metal layer 11 as in the sputtering method.
  • the reactive metal is formed.
  • An antioxidant layer 12 is continuously deposited on the layer 11.
  • the antioxidant layer 12 is made of a metal that is less likely to oxidize in the atmosphere than the reactive metal layer 11 and that allows the copper forming the substrate 20 to react with the reactive metal layer 11 through the antioxidant layer 12 at high temperatures.
  • gold Au
  • silver Au
  • copper Cu
  • tin Sn
  • platinum Pt
  • aluminum Al
  • the antioxidant layer 12 is provided to suppress the oxidation of the reactive metal layer 11 in the atmosphere and the bonding is mainly formed by the reactive metal layer 11, the antioxidant layer 12 is formed by the reactive metal layer 11 and the metal plate. It is preferably thin enough to allow reaction with the 20 side (alloy reaction).
  • the antioxidant layer 12 can be formed by a sputtering method in the same manner as the reactive metal layer 11, the substrate 10 in which the reactive metal layer 11 is formed on the surface (FIG. 1B) is not taken out into the atmosphere. After the film formation of the reactive metal layer 11 (FIG. 1B), the antioxidant layer 12 can be formed by a sputtering method in a vacuum (in a reduced pressure atmosphere).
  • a metal plate 20 separate from the substrate 10 is prepared (FIG. 1D), and this is brought into close contact with the side of the substrate 10 on which the reactive metal layer 11 and the like are formed, and as shown in FIG. 1E, in the thickness direction.
  • Hot pressing is performed by applying pressure and heating (hot pressing step).
  • the substrate 10 and the metal plate 20 are sandwiched by the hot press base 100 on the lower side and the spacer 110 on the upper side, and are pressurized at a predetermined pressure.
  • the atmosphere at this time is preferably a non-oxidizing atmosphere (for example, in vacuum or in argon), the temperature is preferably in the range of 600° C. to 1080° C., and the pressure is preferably in the range of 1 MPa to 100 MPa. If the temperature and pressure are too low, joining is difficult, and if the temperature and pressure are too high, the shape and thickness of the metal plate 20 greatly change due to plastic deformation. If the temperature exceeds 1080° C., melting of Cu occurs.
  • a bonding layer 15 formed by reacting the reactive metal layer 11 with the surrounding material is formed, whereby the metal plate 20 is bonded to the substrate 10.
  • the bonding layer 15 is emphasized in FIG. 1F, as will be described later, the thickness of the bonding layer 15 is actually compared with the thickness of the bonding layer formed when a brazing material is used. Can be ignored.
  • the metal plate 20 When the metal plate 20 is used as wiring, the metal plate 20 is appropriately etched and patterned after the metal plate 20 is bonded to the substrate 10 as shown in FIG. 1F. This step can be performed in the same manner as when DBC or an active metal brazing material is used. The same applies to the step of mounting a power semiconductor element or the like thereafter.
  • the metal plate 20 is bonded to the upper surface side of the substrate 10, but another metal plate 20 can be bonded to the lower surface side as well.
  • the reactive metal layer 11 and the antioxidant layer 12 of FIGS. 1B and 1C are similarly formed on the lower surface side (reactive metal layer forming step), and the metal plate 20 is provided on the lower surface side as well.
  • Pressing may be performed (hot pressing process).
  • the above patterning can be performed individually on the upper surface side and the lower surface side, as in the case of using DBC or an active metal brazing material.
  • the reactive metal layer 11 and the antioxidant layer 12 are sequentially formed on the substrate 10, and then the metal plate 20 is joined, but conversely, it faces the substrate 10 on the metal plate 20.
  • the reactive metal layer 11 and the antioxidant layer 12 may be sequentially formed on the side surface (the lower surface in FIGS. 1A to 1F).
  • the metal plate 20 and the substrate 10 can be joined by performing the same hot pressing step as described above.
  • the reactive metal layer 11 and the antioxidant layer 12 may be formed on both the substrate 10 and the metal plate 20, respectively.
  • the reactive metal layer 11 and the antioxidant layer 12 are formed on only one of the substrate 10 and the metal plate 20.
  • the metal plate 20 may be plastically deformed in the hot press process. Such plastic deformation affects the deformation and warpage of the circuit board after the circuit board is manufactured or when a subsequent thermal cycle is applied.
  • plastic deformation occurs during cooling to room temperature after the hot press process, the stress of the metal plate 20 and the bonding layer 15 at room temperature is reduced, and the warpage of this circuit board at room temperature can be reduced. Therefore, the temperature and pressure in the hot press process can be set not only according to the bonding condition but also according to the warping condition of the circuit board. That is, warping (deformation) of the circuit board at room temperature can be reduced by causing plastic deformation of the metal plate 20 during cooling from the hot pressing step.
  • the pressure of the hot pressing step is such that the bonding layer 15 is formed as described above by the hot pressing step. You can also set the temperature. In this case, the antioxidant layer 12 is unnecessary. The same applies when the oxide layer can be removed by various treatments before the hot press step.
  • the sputtering method it is easy to continuously form the antioxidant layer 12 and the reactive metal layer 11, thereby ensuring the oxidation of the reactive metal layer 11 before the hot pressing step. Since it can be suppressed, it is particularly preferable to sequentially form the reactive metal layer 11 and the antioxidant layer 12 by a sputtering method.
  • the antioxidant layer 12 when the reactive metal layer 11 is Ti, it is preferable to form the antioxidant layer 12 because Ti is oxidized in the air. However, since this oxidation progresses gradually, this situation also depends on the time interval from the reaction metal layer forming step to the hot pressing step. For example, the antioxidant layer 12 is particularly effective when the time interval is several days or more, but when the time interval is negligibly short, the antioxidant layer 12 may not be formed.
  • the eutectic liquid phase of Cu and oxygen (O) constituting the metal plate contributes to the bonding, and there are two types of O, one contained in the metal plate and the other contained in the substrate.
  • O is contained only in a trace amount at the impurity level. Therefore, the bonding strength by DBC is affected by the composition of the metal plate and the substrate, and as described above, when the substrate is made of nitride ceramics, for example, it is difficult to obtain high bonding strength. ..
  • Ti used here as the reactive metal layer 11 is Cu, which is the main component constituting the metal plate 20, and N (in the case of nitride) and O (oxidation) in the ceramic material constituting the substrate 10. (In the case of a product) and the like to form an alloy layer (bonding layer 15). Therefore, regardless of whether the material constituting the substrate 10 is a nitride-based material or an oxide-based material, the bonding layer 15 is stably formed.
  • the reactive metal layer 11 is made of Ti (pure Ti), but as long as the bonding layer 15 is formed in the same manner as described above, the reactive metal layer 11 is made of a material other than Ti. It may be contained. Similarly, as long as it can react with O, N, etc. on the substrate 10 side and Cu on the metal plate 20 side, and as described above, a thin film can be formed on the substrate 10 side or the metal plate 20 side. Other metals may be used as the main component of the reaction metal layer 11.
  • FIG. 2A a metal plate made of copper (oxygen-free copper) is joined to a ceramic substrate made of silicon nitride (Si 3 N 4 ) using an active metal brazing material in which Ag and Ti are added to Cu.
  • FIG. 2B is a cross-sectional SEM photograph of a circuit board formed by joining the metal plate (metal plate 10) to the ceramic substrate (board 10) by the manufacturing method according to the embodiment of the present invention. Is.
  • Ti having a thickness of 0.05 ⁇ m was used as the reactive metal layer 11
  • Ag having a thickness of 0.1 ⁇ m was used as the antioxidant layer 12.
  • a bonding layer having a thickness of about 10 ⁇ m can be clearly confirmed at the boundary between the substrate and the metal plate, but in the case of FIG. 2B as an example, the bonding layer is I can't confirm. Further, the unevenness of the metal plate / substrate interface in FIG. 2B directly reflects the unevenness of the substrate surface. That is, the bonding layer 15 in FIG. 1F is actually very thin, and is significantly thinner than 1 ⁇ m. Alternatively, a bonding layer having a thickness that can be clearly confirmed by at least SEM is not formed. Therefore, the heat dissipation efficiency of the circuit board can be increased regardless of the thermal conductivity of the bonding layer.
  • the thermal conductivity of Ti constituting the reactive metal layer 11 is significantly lower than that of Cu constituting the metal plate 20. Therefore, if Ti remains thick as the reactive metal layer 11 in the bonding layer 15, the substantial thermal conductivity of the bonding layer 15 decreases. On the other hand, since it is only the portion of the reactive metal layer 11 that is alloyed by the reaction of Ti, the Cu of the metal plate 20, the metal element in the substrate 10, and the like, the portion that is alloyed in this way is formed. As long as it is performed, it is preferable that the reaction metal layer 11 is thin, and it is preferable that after the hot pressing step, there are few portions where Ti in the reaction metal layer 11 remains as it is. Therefore, the thickness of the reactive metal layer 11 in FIG.
  • 1C is preferably 1 ⁇ m or less. When this thickness exceeds 1 ⁇ m, the thermal conductivity of the circuit board becomes low. Further, in order to improve the throughput during manufacturing, it is preferable that the reactive metal layer 11 and the antioxidant layer 12 formed by the sputtering method are thin. On the other hand, even when the thickness of the reactive metal layer 11 is set to the lower limit (for example, about 0.01 ⁇ m) of the thickness that can be controlled by film formation by the sputtering method, a strong bond can be obtained. Further, when the thickness of the reactive metal layer 11 is less than 0.01 ⁇ m, it is difficult to control the film thickness, so that an effective film thickness cannot be uniformly obtained, and sufficient bonding strength is obtained. Can be difficult.
  • the thickness of the reactive metal layer 11 is preferably in the range of 0.01 to 1 ⁇ m.
  • the difference in thermal expansion between the metal plate 20 made of Cu and the substrate 10 made of ceramic material becomes large, so that a large shear strain is generated between the metal plate 20 and the substrate 10. Occurs. It is difficult for the bonding interface (bonding layer 15) to take charge of this shear strain only when the bonding layer 15 is thin, and it is difficult to obtain high bonding strength by the bonding layer 15.
  • the pressure and temperature in the hot press process By adjusting the pressure and temperature in the hot press process, the shrinkage and expansion of the metal plate 20 can be restrained, so that this shear strain can be reduced. That is, in the above manufacturing method, the setting of pressure and temperature in the hot pressing process is particularly important. At this time, by bringing the thermal expansion coefficient of the spacer 110 used in FIG.
  • this shear strain can be particularly reduced.
  • a material for such a spacer 110 it is particularly preferable to use a CIP (Cold Isostatic Press) material carbon plate, a heat-resistant plate, and a ceramic plate similar to the substrate 10.
  • CIP Cold Isostatic Press
  • the size of the substrate 10 was 190 mm ⁇ 138 mm ⁇ 0.32 mm
  • the size of the metal plate 20 was 190 mm ⁇ 138 mm.
  • Ti was used as the reaction metal layer 11, the thickness was changed, and the hot pressing conditions were kept constant to measure the bonding strength.
  • the Ti film was formed by DC sputtering, the power was set to 400 W, and only a film forming time was changed to set a plurality of kinds of film thicknesses.
  • the antioxidant layer 12 was made of Ag having a thickness of 0.1 ⁇ m, and the reactive metal layer 11 and the antioxidant layer 12 were formed on the substrate 10 side as shown in FIG. 1C.
  • the hot press conditions were 800° C. and 10 MPa.
  • the metal plate 20 was a 0.3 mm copper (oxygen-free copper) plate, the substrate 10 was SiN, and the spacer 110 was a CIP carbon plate.
  • the film thickness of Ti was calculated from the weight before and after the film formation.
  • the metal plate 20 in the structure (circuit board) after bonding is etched to a size of 2 mm square, a copper wire is soldered to the surface, and the load of pulling the copper wire in the vertical direction to peel it off is measured. Then, it was calculated by dividing by the area (4 mm 2 ). The results are shown in Table 1.
  • the joint strength was measured by changing the hot press conditions (temperature, pressure).
  • the film thickness of the reactive metal layer (Ti) is 0.05 ⁇ m
  • the antioxidant layer 12 is Ag with a film thickness of 0.1 ⁇ m
  • the reactive metal layer 11 and the antioxidant layer 12 are on the substrate 10 side as shown in FIG. 1C.
  • the metal plate 20 was a 0.3 mm thick copper plate
  • the substrate 10 was SiN
  • the spacer 110 was a CIP carbon plate. The results are shown in Table 2.
  • BeO beryllium
  • Hot pressing was performed at 850 ° C. and 10 MPa using 0.05 ⁇ m Ti as the reactive metal layer 11 and 0.05 ⁇ m Ag as the antioxidant layer 12. It was difficult to measure the bonding strength similar to the above because the material of the substrate 10 was different, but FIG. 3 shows a photograph of the interface after peeling as described above.
  • BeO itself constituting the substrate 10 is destroyed, it can be confirmed that at least the bonding strength exceeds the fracture strength of the substrate 10. Therefore, the above manufacturing method is effective even when a BeO substrate is used.
  • Al 2 O 3 , AlN, or the like can be used in addition to SiN and BeO. All of these materials have high insulation properties and are preferably used as materials for circuit boards. In addition, O and N that react with the reactive metal layer 11 are included as constituent elements.
  • Zr can be used as the material constituting the reactive metal layer 11 in addition to the above Ti. Like Ti, Zr can be easily formed with a film thickness in the above range by a sputtering method.
  • metal plate 20 a metal plate 20 made of pure copper (oxygen-free copper) was used in the above example, but it is clear that the above manufacturing method is similarly effective as long as it contains at least copper as a main component. Is. Therefore, a copper alloy can be used as the metal plate 20.

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  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
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  • Parts Printed On Printed Circuit Boards (AREA)

Abstract

A circuit board production method whereby a bonding layer formed between a metal sheet and a substrate in a circuit board can be kept thin and high bonding strength can be obtained between the metal sheet and the substrate.　A reactive metal layer (11) and an antioxidation layer (12) are formed, in order, upon this substrate (10), as indicated in diagram 1C (reactive metal layer formation step). The reactive metal layer (11) comprises a metal that, under high temperature, forms a reactive layer or alloy with the material constituting the substrate (10) and the material (Cu) constituting the metal sheet (20). Titanium (Ti), for example, can be used as this material. Then a metal sheet (20) separate from the substrate (10) is prepared. This is adhered to the side of the substrate (10) that has the reactive metal layer (11), etc., formed thereupon and hot pressing is performed whereby pressure is applied in the thickness direction and heating is applied (hot press step).

Description

回路基板の製造方法Circuit board manufacturing method
　本発明は、絶縁性の基板に、銅を主成分とする金属板が接合された回路基板の製造方法に関する。 The present invention relates to a method for manufacturing a circuit board in which a metal plate containing copper as a main component is bonded to an insulating substrate.
　大電流で動作するパワー半導体素子等は回路基板上に搭載されて用いられ、この回路基板は、絶縁性で高い機械的強度をもつ絶縁性基板の上に、配線パターンとなる金属板が接合されて構成される。金属板は、搭載するパワー半導体素子の動作時における放熱のためにも用いられる。 Power semiconductor elements that operate with a large current are mounted on a circuit board and used. In this circuit board, a metal plate that serves as a wiring pattern is bonded onto an insulating substrate that is insulating and has high mechanical strength. Consists of The metal plate is also used for heat dissipation during operation of the mounted power semiconductor element.
　一般的に、絶縁性基板を構成する材料としては、アルミナ、窒化アルミニウム、窒化珪素等の、絶縁性、機械的強度が高いセラミックス材料が用いられる。金属板を構成する材料としては、導電率、熱伝導率が高い銅あるいはその合金が用いられる。パワー半導体素子を搭載したこのような回路基板が用いられた機器においては、パワー半導体素子の動作時にはその発熱により温度が上昇し、停止時には温度が室温に近づくという動作が繰り返されるため、この回路基板には多数回の冷熱サイクルが印加される。前記のような絶縁性基板を構成する材料と金属板を構成する材料の熱膨張係数は大きく異なるため、この冷熱サイクルに際しては、熱膨張の差に起因して回路基板の変形、反りが発生し、このために金属板が絶縁性基板から剥離するおそれがある。このため、回路基板における金属板と絶縁性基板との間の接合強度が高いことが要求される。 Generally, ceramic materials such as alumina, aluminum nitride, and silicon nitride, which have high insulation and mechanical strength, are used as the material for the insulating substrate. As a material constituting the metal plate, copper or an alloy thereof having high conductivity and thermal conductivity is used. In a device using such a circuit board equipped with a power semiconductor element, the temperature rises due to the heat generated when the power semiconductor element is operated, and the temperature approaches room temperature when the power semiconductor element is stopped. Therefore, this circuit board is repeatedly used. Is applied with a large number of cooling and heating cycles. Since the thermal expansion coefficient of the material forming the insulating substrate and the material forming the metal plate are greatly different from each other, during the cooling/heating cycle, the circuit board is deformed or warped due to the difference in thermal expansion. Therefore, the metal plate may be peeled off from the insulating substrate. Therefore, it is required that the bonding strength between the metal plate and the insulating substrate in the circuit board is high.
　一般的には、このような異なる物質同士を高い接合強度で接合するためには、ろう材が用いられている。この場合、バインダ（有機材料）とろう材を構成する金属粒子とが混合されたろう材ペーストが基板上に塗布され、ろう材を溶融させた後で金属板と絶縁性基板の間で固化させることによって、接合が行われる。ろう材（ろう材を構成する金属材料）の種類は、金属板や絶縁性基板よりも融点が十分に低く、かつろう材が溶融した後で固化して形成された接合層によって、金属板と絶縁性基板との間の接合強度が安定して十分に高くなるように選定される。 Generally, a brazing material is used to bond such different substances with high bonding strength. In this case, a brazing material paste in which a binder (organic material) and metal particles constituting the brazing material are mixed is applied onto the substrate, the brazing material is melted, and then solidified between the metal plate and the insulating substrate. The joining is performed by. The type of brazing material (metal material constituting the brazing material) has a melting point sufficiently lower than that of a metal plate or an insulating substrate, and is formed by solidifying the brazing material after it has melted. It is selected so that the bonding strength with the insulating substrate is stable and sufficiently high.
　これに対し、例えば特許文献１には、上記のような金属板と絶縁性基板との間の接合のためにろう材等の接合のための層を特に設けずに、銅で構成された金属板とセラミックス基板とを接合する直接接合法（ダイレクトボンディングカッパー：ＤＢＣ）が記載されている。ＤＢＣにおいては、銅で構成された金属板とセラミックス基板を密着させて所定の高温とすることにより、金属板を構成する銅と、金属板中に僅かに含有される酸素との共晶液相を発生させ、この液相がろう材と同様に接合のために機能する。ただし、上記のように塗布による厚いろう材を用いる場合とは異なり、実質的には接合層の厚さは無視できる程度となり、実質的には絶縁性基板と金属板が直接接合される。この接合法は、セラミックス基板がアルミナ等の酸化物である場合には特に有効である。しかしながら、近年は、放熱特性の向上のために、より高い熱伝導率をもつ窒化物系（窒化アルミニウム、窒化珪素等）のセラミックス材料で構成された絶縁性基板（セラミックス基板）が広く用いられている。このような窒化物系のセラミックス基板においては、表面における共晶液相の濡れ性が低くなるために、ＤＢＣで一様な高い接合強度を得ることが困難であった。 On the other hand, for example, in Patent Document 1, a metal made of copper is not particularly provided with a layer for joining a brazing material or the like for joining between the metal plate and the insulating substrate as described above. A direct bonding method (direct bonding copper: DBC) for bonding a plate and a ceramic substrate is described. In DBC, a metal plate made of copper and a ceramic substrate are brought into close contact with each other to a predetermined high temperature, so that the copper constituting the metal plate and oxygen slightly contained in the metal plate are co-crystal liquid phases. And the liquid phase acts like a braze for bonding. However, unlike the case where a thick brazing material by coating is used as described above, the thickness of the bonding layer is substantially negligible, and the insulating substrate and the metal plate are substantially directly bonded. This joining method is particularly effective when the ceramic substrate is an oxide such as alumina. However, in recent years, in order to improve heat dissipation characteristics, an insulating substrate (ceramic substrate) made of a nitride-based (aluminum nitride, silicon nitride, etc.) ceramic material having a higher thermal conductivity has been widely used. There is. In such a nitride-based ceramic substrate, the wettability of the eutectic liquid phase on the surface is low, and thus it is difficult to obtain uniform high bonding strength with DBC.
　一方、例えば特許文献２には、活性金属であるＴｉを含有した活性金属ろう材を用いて金属板とセラミックス基板とを接合する技術が記載されている。この技術においては、Ｔｉから形成されるＴｉＮが接合に寄与する。また、活性金属ろう材にはＡｇ、Ｃｕが含まれ、溶融、固化後の接合層は主に主にＡｇ－Ｃｕ合金で構成される。ＤＢＣの場合には実質的には接合層は存在しないのに対し、この場合には、このような接合層が金属板とセラミックス基板の間に形成される。窒化物で構成されたセラミックス基板との接合の際には、まずＴｉが優先的にセラミックス基板側に拡散してＴｉＮが形成された上で上記の接合層が形成されることによって、一様な接合が得られる。このため、ＤＢＣとは異なり、このような活性金属ろう材を用いた場合には、窒化物系のセラミックス基板に対しても強固な接合を行うことができる。 On the other hand, for example, Patent Document 2 describes a technique for joining a metal plate and a ceramic substrate using an active metal brazing material containing Ti, which is an active metal. In this technique, TiN formed from Ti contributes to the bonding. Further, the active metal brazing material contains Ag and Cu, and the bonding layer after melting and solidification is mainly composed of an Ag—Cu alloy. In the case of DBC, there is substantially no bonding layer, whereas in this case, such a bonding layer is formed between the metal plate and the ceramic substrate. At the time of joining with a ceramic substrate made of a nitride, first, Ti is preferentially diffused to the side of the ceramic substrate to form TiN, and then the above-mentioned joining layer is formed, so that uniform bonding is achieved. A bond is obtained. Therefore, unlike DBC, when such an active metal brazing material is used, strong bonding can be performed even on a nitride-based ceramic substrate.
特開平５－２４３７２５号公報JP-A-5-243725 特開２０１５－１７４０９７号公報JP, 2005-174097, A
　このように形成される接合層（合金層）の熱伝導率は、一般的には金属板等と比べて低い。このため、回路基板としての十分な放熱特性を得るためには、この接合層を十分に薄くすることが必要であった。これに対し、上記のような活性金属ろう材（ろう材）を用いた場合には、接合層を十分に薄くすることは困難であるため、放熱効率を高くすることが困難であった。 The thermal conductivity of the bonded layer (alloy layer) formed in this way is generally lower than that of a metal plate or the like. Therefore, in order to obtain sufficient heat dissipation characteristics as a circuit board, it is necessary to make the bonding layer sufficiently thin. On the other hand, when the above-mentioned active metal brazing material (brazing material) is used, it is difficult to make the bonding layer sufficiently thin, so that it is difficult to increase the heat dissipation efficiency.
　また、この接合層自身の機械的強度は必ずしも十分ではない場合もあり、接合層自身が冷熱サイクルに際して破壊することがあった。このため、活性金属ろう材を用いた回路基板の冷熱サイクルに対する耐久性は十分ではなかった。 In addition, the mechanical strength of the bonding layer itself may not always be sufficient, and the bonding layer itself may break during the thermal cycle. For this reason, the durability of the circuit board using the active metal brazing material against the cooling and heating cycle was not sufficient.
　また、回路基板の放熱効率を高めるためには、金属板を十分に厚くする場合もある。ＤＢＣを用いた場合において、例えば０．３ｍｍ以上の厚さの金属板を強固に接合することは実際には困難であった。このため、ＤＢＣを用いた場合においても、厚い金属板を用いた場合には冷熱サイクルに対する耐久性は必ずしも十分ではなかった。 In addition, in order to improve the heat dissipation efficiency of the circuit board, the metal plate may be made sufficiently thick. When DBC is used, it is actually difficult to firmly join a metal plate having a thickness of, for example, 0.3 mm or more. Therefore, even when the DBC is used, the durability against the thermal cycle is not always sufficient when the thick metal plate is used.
　このため、金属板と基板との間に形成される接合層を薄くしつつ、金属板と基板との間の高い接合強度を得ることのできる技術が望まれた。 Therefore, a technology that can obtain a high bonding strength between the metal plate and the substrate while thinning the bonding layer formed between the metal plate and the substrate has been desired.
　本発明は、かかる問題点に鑑みてなされたものであり、上記問題点を解決する発明を提供することを目的とする。 The present invention has been made in view of such problems, and an object of the present invention is to provide an invention that solves the above problems.
　本発明は、上記課題を解決すべく、以下に掲げる構成とした。
　本発明の回路基板の製造方法は、絶縁性の基板の表面に銅（Ｃｕ）又は銅合金で構成された金属板が接合された構成を具備する回路基板の製造方法であって、前記基板、前記金属板のうちの少なくともいずれかの表面に、前記基板及び前記金属板と反応をする金属を含む反応金属層を成膜する反応金属層成膜工程と、前記反応金属層が前記基板と前記金属板との間にある形態で前記基板と前記金属板とを積層し、非酸化雰囲気中で、前記反応金属層と前記金属板及び前記基板との間で反応が生じる温度で前記基板と前記金属板の間に圧力を印加するホットプレス工程と、を具備することを特徴とする。
　本発明の回路基板の製造方法において、前記反応金属層はチタン（Ｔｉ）を含むことを特徴とする。
　本発明の回路基板の製造方法は、前記反応金属層の厚さを０．０１～１μｍの範囲とすることを特徴とする。
　本発明の回路基板の製造方法において、前記基板はアルミナ、窒化珪素、窒化アルミニウム、ベリリアのうちのいずれかを主成分とする材料で構成されたことを特徴とする。
　本発明の回路基板の製造方法は、前記ホットプレス工程を、温度６００℃以上の範囲、圧力１ＭＰａ以上の範囲で行うことを特徴とする。
　本発明の回路基板の製造方法は、前記反応金属層成膜工程において、前記反応金属層の上に、前記反応金属層とは異なる材料で構成された酸化防止層を形成することを特徴とする。
　本発明の回路基板の製造方法において、前記酸化防止層は金（Ａｕ）、銀（Ａｇ）、銅（Ｃｕ）、錫（Ｓｎ）、白金（Ｐｔ）、アルミニウム（Ａｌ）のいずれかを含むことを特徴とする。
　本発明の回路基板の製造方法において、前記反応金属層成膜工程はスパッタリング法により行われることを特徴とする。
　本発明の回路基板の製造方法は、前記ホットプレス工程において、前記金属板はスペーサを介して加圧され、前記スペーサはカーボン板、耐熱ガラス板、セラミックス板のいずれかで構成されたことを特徴とする。 The present invention has the following configurations in order to solve the above problems.
The method for manufacturing a circuit board of the present invention is a method for manufacturing a circuit board having a structure in which a metal plate made of copper (Cu) or a copper alloy is bonded to the surface of an insulating substrate. A reaction metal layer forming step of forming a reaction metal layer containing a metal that reacts with the substrate and the metal plate on at least one surface of the metal plate; The substrate and the metal plate are laminated in a form between the metal plate and the substrate and the metal plate in a non-oxidizing atmosphere at a temperature at which a reaction occurs between the reaction metal layer and the metal plate and the substrate. It is characterized by comprising a hot pressing step of applying pressure between metal plates.
In the method for manufacturing a circuit board according to the present invention, the reactive metal layer contains titanium (Ti).
The method of manufacturing a circuit board according to the present invention is characterized in that the thickness of the reaction metal layer is set in the range of 0.01 to 1 μm.
The circuit board manufacturing method of the present invention is characterized in that the substrate is made of a material containing any one of alumina, silicon nitride, aluminum nitride, and beryllium as a main component.
The method for manufacturing a circuit board of the present invention is characterized in that the hot pressing step is performed at a temperature of 600° C. or higher and a pressure of 1 MPa or higher.
The method for producing a circuit board of the present invention is characterized in that, in the reaction metal layer forming step, an antioxidant layer made of a material different from the reaction metal layer is formed on the reaction metal layer. ..
In the method for producing a circuit board of the present invention, the antioxidant layer contains any one of gold (Au), silver (Ag), copper (Cu), tin (Sn), platinum (Pt), and aluminum (Al). Is characterized by.
The circuit board manufacturing method of the present invention is characterized in that the reactive metal layer film forming step is performed by a sputtering method.
The method for manufacturing a circuit board of the present invention is characterized in that, in the hot pressing step, the metal plate is pressurized via a spacer, and the spacer is composed of any of a carbon plate, a heat-resistant glass plate, and a ceramic plate. And
　本発明は以上のように構成されているので、回路基板において、金属板と基板との間に形成される接合層を薄くしつつ、金属板と基板との間の高い接合強度を得ることができる。 Since the present invention is configured as described above, it is possible to obtain a high bonding strength between the metal plate and the substrate while thinning the bonding layer formed between the metal plate and the substrate in the circuit board. it can.
本発明の実施の形態に係る回路基板の製造方法を示す工程断面図（その１）である。It is a process sectional view (the 1) which shows the manufacturing method of the circuit board which concerns on embodiment of this invention. 本発明の実施の形態に係る回路基板の製造方法を示す工程断面図（その２）である。It is a process sectional view (the 2) which shows the manufacturing method of the circuit board which concerns on embodiment of this invention. 本発明の実施の形態に係る回路基板の製造方法を示す工程断面図（その３）である。It is a process sectional view (No. 3) which shows the manufacturing method of the circuit board which concerns on embodiment of this invention. 本発明の実施の形態に係る回路基板の製造方法を示す工程断面図（その４）である。It is a process sectional view (the 4) which shows the manufacturing method of the circuit board which concerns on embodiment of this invention. 本発明の実施の形態に係る回路基板の製造方法を示す工程断面図（その５）である。It is a process sectional view (No. 5) which shows the manufacturing method of the circuit board which concerns on embodiment of this invention. 本発明の実施の形態に係る回路基板の製造方法を示す工程断面図（その６）である。It is a process sectional view (No. 6) which shows the manufacturing method of the circuit board which concerns on embodiment of this invention. 活性ろう材を接合に用いた場合の回路基板の断面ＳＥＭ写真である。It is a cross-sectional SEM photograph of a circuit board when an active brazing material is used for bonding. 実施例の製造方法により接合を行った場合の回路基板の断面ＳＥＭ写真である。It is a cross-sectional SEM photograph of a circuit board when joining is performed by the manufacturing method of an Example. 実施例の製造方法によりＢｅＯ基板に対して接合を行った後で金属板を剥離した後の顕微鏡写真である。It is a micrograph after peeling off a metal plate after bonding to a BeO substrate by the manufacturing method of the example.
　本発明の実施の形態に係る回路基板の製造方法について説明する。図１Ａ～図１Ｆは、この製造方法の概要を示す工程断面図である。ここで製造される回路基板は、絶縁性の基板１０の表面（図１Ａ等における上面）に金属板２０が接合されて構成される。図１Ａに示された基板１０は、窒化珪素（ＳｉＮ）、窒化アルミニウム（ＡｌＮ）等の窒化物系セラミックスや、アルミナ（酸化アルミニウム：Ａｌ２Ｏ３）、ベリリア（酸化ベリリウム：ＢｅＯ）等の酸化物系セラミックスを主成分とする絶縁性のセラミックス材料で構成される。これらの材料は、いずれも、高い絶縁性、機械的強度を有するため、この上に例えば大電力で動作するパワー半導体素子（パワーＭＯＳＦＥＴ等）を搭載して好ましく用いることができる。特に、窒化珪素等の窒化物系セラミックスは、酸化物系セラミックスと比べて高い熱伝導率をもつため、これを用いた回路基板の放熱効率を高くすることができる。 A method of manufacturing a circuit board according to an embodiment of the present invention will be described. 1A to 1F are process cross-sectional views showing an outline of this manufacturing method. The circuit board manufactured here is configured by bonding the metal plate 20 to the surface (the upper surface in FIG. 1A etc.) of the insulating board 10. The substrate 10 shown in FIG. 1A is formed by oxidizing nitride-based ceramics such as silicon nitride (SiN) and aluminum nitride (AlN), and oxidation of alumina (aluminum oxide: Al 2 O 3 ), beryllium oxide (beryllium oxide: BeO), and the like. It is composed of an insulating ceramic material whose main component is physical ceramics. Since all of these materials have high insulation and mechanical strength, a power semiconductor element (power MOSFET or the like) that operates at high power can be mounted on the material and used preferably. In particular, since nitride-based ceramics such as silicon nitride has a higher thermal conductivity than oxide-based ceramics, the heat dissipation efficiency of the circuit board using the same can be increased.
　この基板１０の上に、パワー半導体素子の配線や放熱板として用いられる金属板２０が接合される。金属板２０は銅（Ｃｕ）や銅合金で構成される。図１Ａ～図１Ｆにおいては、この金属板２０が基板１０に接合されるまでの工程が示されている。基板１０の厚さは例えば数１００μｍ以上、大きさ（縦横）は１００ｍｍ程度であり、上記の材料で構成されたセラミックス基板を基板１０として用いることができる。 A metal plate 20 used as a wiring for a power semiconductor element and a heat sink is bonded onto the substrate 10. The metal plate 20 is made of copper (Cu) or a copper alloy. In FIGS. 1A to 1F, a process until the metal plate 20 is joined to the substrate 10 is shown. The thickness of the substrate 10 is, for example, several hundred μm or more, and the size (length and width) is about 100 mm, and a ceramic substrate made of the above materials can be used as the substrate 10.
　次に、図１Ｂ、図１Ｃに示されるように、この基板１０の上に、反応金属層１１、酸化防止層１２が順次成膜される（反応金属層成膜工程）。反応金属層１１は、高温下で基板１０を構成する材料、金属板２０を構成する材料（Ｃｕ）と反応層や合金を形成するような金属で構成され、この材料としては例えばチタン（Ｔｉ）が用いられる。Ｔｉは、基板２０におけるＣｕと合金を形成すると共に、基板１０が窒化物系の材料である場合には化合物としてＴｉＮを、酸化物系の材料である場合には化合物としてＴｉＯを形成するため、特に好ましく用いることができる。 Next, as shown in FIGS. 1B and 1C, the reactive metal layer 11 and the antioxidant layer 12 are sequentially formed on the substrate 10 (reactive metal layer forming step). The reaction metal layer 11 is composed of a material that forms the substrate 10 and a material that forms the metal plate 20 (Cu) at a high temperature, and a metal that forms a reaction layer or an alloy. As this material, for example, titanium (Ti) is used. Is used. Ti forms an alloy with Cu in the substrate 20, and forms TiN as a compound when the substrate 10 is a nitride-based material, and TiO as a compound when the substrate 10 is an oxide-based material. It can be used particularly preferably.
　反応金属層１１の成膜は、例えばスパッタリング法によって行われ、その厚さは基板１０や金属板２０や、塗布されて使用されるろう材（活性金属ろう材）よりも大幅に薄く形成され、その厚さは例えば０．０１μｍ～１０μｍの範囲とされる。反応金属層１１は、後述するように、これが基板１０や金属板２０と反応して接合層を形成するためのみに用いられ、接合層を薄くするためには、薄いことが好ましい。 The reaction metal layer 11 is formed by, for example, a sputtering method, and its thickness is formed to be significantly thinner than that of the substrate 10, the metal plate 20, and the brazing material (active metal brazing material) applied and used. The thickness is, for example, in the range of 0.01 μm to 10 μm. As will be described later, the reactive metal layer 11 is used only for reacting with the substrate 10 and the metal plate 20 to form a bonding layer, and is preferably thin in order to thin the bonding layer.
　Ｔｉは大気中では容易に酸化するが、上記のスパッタリング法は真空中（減圧雰囲気中）で行われ、反応金属層成膜工程の間に反応金属層１１が酸化することは抑制される。反応金属層成膜工程においては、スパッタリング法と同様に反応金属層１１を酸化させずに薄く成膜することのできる他の方法として、真空蒸着法を用いてもよい。 Ti is easily oxidized in the atmosphere, but the above sputtering method is performed in a vacuum (in a reduced pressure atmosphere), and the oxidation of the reactive metal layer 11 during the reaction metal layer film forming step is suppressed. In the reactive metal layer forming step, a vacuum deposition method may be used as another method capable of forming a thin film without oxidizing the reactive metal layer 11 as in the sputtering method.
　また、後述するホットプレス工程が行われる前において、反応金属層１１が形成された後で大気中に取り出された際に酸化することを防止するために、図１Ｃに示されるように、反応金属層１１の上に酸化防止層１２が連続して成膜される。酸化防止層１２は、反応金属層１１よりも大気中で酸化しにくく、かつ高温下では酸化防止層１２を通して基板２０を構成する銅と反応金属層１１とが反応することが可能な金属で構成され、具体的には、金（Ａｕ）、銀（Ａｇ）、銅（Ｃｕ）、錫（Ｓｎ）、白金（Ｐｔ）、アルミニウム（Ａｌ）のいずれかを用いることができる。酸化防止層１２は反応金属層１１の大気中での酸化を抑制するために設けられ、接合は主に反応金属層１１によって形成されるため、酸化防止層１２は、反応金属層１１と金属板２０側との反応（合金反応）が可能となる程度に薄いことが好ましい。 Further, as shown in FIG. 1C, in order to prevent oxidation when the reactive metal layer 11 is taken out into the atmosphere after being formed before the hot pressing step described later is performed, the reactive metal is formed. An antioxidant layer 12 is continuously deposited on the layer 11. The antioxidant layer 12 is made of a metal that is less likely to oxidize in the atmosphere than the reactive metal layer 11 and that allows the copper forming the substrate 20 to react with the reactive metal layer 11 through the antioxidant layer 12 at high temperatures. Specifically, any one of gold (Au), silver (Ag), copper (Cu), tin (Sn), platinum (Pt), and aluminum (Al) can be used. Since the antioxidant layer 12 is provided to suppress the oxidation of the reactive metal layer 11 in the atmosphere and the bonding is mainly formed by the reactive metal layer 11, the antioxidant layer 12 is formed by the reactive metal layer 11 and the metal plate. It is preferably thin enough to allow reaction with the 20 side (alloy reaction).
　酸化防止層１２は、反応金属層１１と同様にスパッタリング法で成膜することができるため、反応金属層１１が表面に成膜された状態（図１Ｂ）の基板１０を大気中に取り出すことなく、反応金属層１１の成膜（図１Ｂ）に引き続いて真空中（減圧雰囲気中）で酸化防止層１２をスパッタリング法で成膜することができる。 Since the antioxidant layer 12 can be formed by a sputtering method in the same manner as the reactive metal layer 11, the substrate 10 in which the reactive metal layer 11 is formed on the surface (FIG. 1B) is not taken out into the atmosphere. After the film formation of the reactive metal layer 11 (FIG. 1B), the antioxidant layer 12 can be formed by a sputtering method in a vacuum (in a reduced pressure atmosphere).
　その後、基板１０と別体の金属板２０を準備し（図１Ｄ）、これを基板１０における反応金属層１１等が形成された側と密着させ、図１Ｅに示されるように、厚さ方向に圧力を印加すると共に加熱するホットプレスを行う（ホットプレス工程）。ここで、基板１０、金属板２０は、下側でホットプレス基台１００、上側でスペーサ１１０によって挟持されて所定の圧力で加圧される。この際の雰囲気は非酸化雰囲気（例えば真空中、アルゴン中）とし、温度は６００℃～１０８０℃の範囲、圧力は１ＭＰａ～１００ＭＰａの範囲が好ましい。温度、圧力が低すぎる場合には接合が困難であり、温度、圧力が高すぎる場合には塑性変形により金属板２０の形状や厚さが大きく変動する。温度が１０８０℃を超える場合には、Ｃｕの溶融が発生する。 After that, a metal plate 20 separate from the substrate 10 is prepared (FIG. 1D), and this is brought into close contact with the side of the substrate 10 on which the reactive metal layer 11 and the like are formed, and as shown in FIG. 1E, in the thickness direction. Hot pressing is performed by applying pressure and heating (hot pressing step). Here, the substrate 10 and the metal plate 20 are sandwiched by the hot press base 100 on the lower side and the spacer 110 on the upper side, and are pressurized at a predetermined pressure. The atmosphere at this time is preferably a non-oxidizing atmosphere (for example, in vacuum or in argon), the temperature is preferably in the range of 600° C. to 1080° C., and the pressure is preferably in the range of 1 MPa to 100 MPa. If the temperature and pressure are too low, joining is difficult, and if the temperature and pressure are too high, the shape and thickness of the metal plate 20 greatly change due to plastic deformation. If the temperature exceeds 1080° C., melting of Cu occurs.
　これにより、図１Ｆに示されるように、反応金属層１１が周囲の材料と反応して形成された接合層１５が形成され、これによって金属板２０が基板１０と接合される。なお、図１Ｆでは接合層１５は強調して示されているが、後述するように、実際にはこの接合層１５の厚さはろう材を用いた場合に形成される接合層の厚さと比べて無視できる程度となる。 As a result, as shown in FIG. 1F, a bonding layer 15 formed by reacting the reactive metal layer 11 with the surrounding material is formed, whereby the metal plate 20 is bonded to the substrate 10. Although the bonding layer 15 is emphasized in FIG. 1F, as will be described later, the thickness of the bonding layer 15 is actually compared with the thickness of the bonding layer formed when a brazing material is used. Can be ignored.
　金属板２０を配線として用いる場合には、図１Ｆに示されるように金属板２０が基板１０に接合された後で、金属板２０は適宜エッチングされてパターニングされる。この工程は、ＤＢＣや活性金属ろう材を用いた場合と同様に行うことができる。その後に、パワー半導体素子等を搭載する工程についても同様である。 When the metal plate 20 is used as wiring, the metal plate 20 is appropriately etched and patterned after the metal plate 20 is bonded to the substrate 10 as shown in FIG. 1F. This step can be performed in the same manner as when DBC or an active metal brazing material is used. The same applies to the step of mounting a power semiconductor element or the like thereafter.
　また、図１Ａ～図１Ｆの例では基板１０の上面側に金属板２０が接合されたが、下面側にも同様に他の金属板２０を接合することもできる。この場合には、図１Ｂ、図１Ｃの反応金属層１１、酸化防止層１２を下面側にも同様に形成し（反応金属層形成工程）、下面側にも金属板２０を設けた状態でホットプレスを行えばよい（ホットプレス工程）。この場合、上記のパターニングは、ＤＢＣや活性金属ろう材を用いた場合と同様に、上面側と下面側で個別に行うことができる。 Further, in the examples of FIGS. 1A to 1F, the metal plate 20 is bonded to the upper surface side of the substrate 10, but another metal plate 20 can be bonded to the lower surface side as well. In this case, the reactive metal layer 11 and the antioxidant layer 12 of FIGS. 1B and 1C are similarly formed on the lower surface side (reactive metal layer forming step), and the metal plate 20 is provided on the lower surface side as well. Pressing may be performed (hot pressing process). In this case, the above patterning can be performed individually on the upper surface side and the lower surface side, as in the case of using DBC or an active metal brazing material.
　また、上記の例では、基板１０の上に反応金属層１１、酸化防止層１２が順次形成された上で、金属板２０が接合されたが、逆に、金属板２０における基板１０と相対する側の面（図１Ａ～図１Ｆにおいては下側の面）に反応金属層１１、酸化防止層１２を順次形成してもよい。この場合においても、上記と同様のホットプレス工程を行うことにより、金属板２０と基板１０を接合することができる。あるいは、基板１０、金属板２０の両者にそれぞれ反応金属層１１、酸化防止層１２を形成してもよい。ただし、製造工程を簡略化し、かつ形成される接合層を薄くするためには、反応金属層１１、酸化防止層１２は、基板１０、金属板２０のうちの一方にのみ形成することが好ましい。 Further, in the above example, the reactive metal layer 11 and the antioxidant layer 12 are sequentially formed on the substrate 10, and then the metal plate 20 is joined, but conversely, it faces the substrate 10 on the metal plate 20. The reactive metal layer 11 and the antioxidant layer 12 may be sequentially formed on the side surface (the lower surface in FIGS. 1A to 1F). Also in this case, the metal plate 20 and the substrate 10 can be joined by performing the same hot pressing step as described above. Alternatively, the reactive metal layer 11 and the antioxidant layer 12 may be formed on both the substrate 10 and the metal plate 20, respectively. However, in order to simplify the manufacturing process and thin the formed bonding layer, it is preferable that the reactive metal layer 11 and the antioxidant layer 12 are formed on only one of the substrate 10 and the metal plate 20.
　また、前記の通り、ホットプレス工程においては、金属板２０が塑性変形することがある。このような塑性変形は、回路基板の製造後、あるいはその後の熱サイクルが印加された際の回路基板の変形、反りの状態に影響を及ぼす。ホットプレス工程後の室温までの冷却時に塑性変形が生じた場合には、室温時における金属板２０や接合層１５の応力が低減され、この回路基板の室温時における反りを小さくすることができる。このため、ホットプレス工程の温度、圧力は、接合の状況だけでなく、このような回路基板の反りの状況に応じても設定することができる。すなわち、ホットプレス工程からの冷却時において金属板２０に塑性変形を発生させることにより、回路基板の室温時における反り（変形）を小さくすることができる。 Further, as described above, the metal plate 20 may be plastically deformed in the hot press process. Such plastic deformation affects the deformation and warpage of the circuit board after the circuit board is manufactured or when a subsequent thermal cycle is applied. When plastic deformation occurs during cooling to room temperature after the hot press process, the stress of the metal plate 20 and the bonding layer 15 at room temperature is reduced, and the warpage of this circuit board at room temperature can be reduced. Therefore, the temperature and pressure in the hot press process can be set not only according to the bonding condition but also according to the warping condition of the circuit board. That is, warping (deformation) of the circuit board at room temperature can be reduced by causing plastic deformation of the metal plate 20 during cooling from the hot pressing step.
　また、室温時において反応金属層１１（Ｔｉ）の最表面に薄い酸化層が形成された場合でも、ホットプレス工程によって前記のように接合層１５が形成されるように、ホットプレス工程の圧力、温度を設定することもできる。この場合においては、上記の酸化防止層１２は不要である。また、ホットプレス工程の前に酸化層が各種の処理により除去可能な場合においても同様である。ただし、前記のように、スパッタリング法によれば酸化防止層１２と反応金属層１１を連続的に形成することは容易であり、これによってホットプレス工程の前における反応金属層１１の酸化を確実に抑制することができるため、スパッタリング法によって反応金属層１１、酸化防止層１２を順次形成することが特に好ましい。例えば反応金属層１１をＴｉとした場合には、Ｔｉは空気中で酸化するために、酸化防止層１２を形成することが好ましい。ただし、この酸化は徐々に進行するため、この状況は反応金属層成膜工程からホットプレス工程までの時間間隔にも依存する。例えば、この時間間隔が数日以上である場合には、酸化防止層１２は特に有効であるが、この時間間隔が無視できる程度に短い場合には、酸化防止層１２を形成しなくともよい。 Further, even when a thin oxide layer is formed on the outermost surface of the reactive metal layer 11 (Ti) at room temperature, the pressure of the hot pressing step is such that the bonding layer 15 is formed as described above by the hot pressing step. You can also set the temperature. In this case, the antioxidant layer 12 is unnecessary. The same applies when the oxide layer can be removed by various treatments before the hot press step. However, as described above, according to the sputtering method, it is easy to continuously form the antioxidant layer 12 and the reactive metal layer 11, thereby ensuring the oxidation of the reactive metal layer 11 before the hot pressing step. Since it can be suppressed, it is particularly preferable to sequentially form the reactive metal layer 11 and the antioxidant layer 12 by a sputtering method. For example, when the reactive metal layer 11 is Ti, it is preferable to form the antioxidant layer 12 because Ti is oxidized in the air. However, since this oxidation progresses gradually, this situation also depends on the time interval from the reaction metal layer forming step to the hot pressing step. For example, the antioxidant layer 12 is particularly effective when the time interval is several days or more, but when the time interval is negligibly short, the antioxidant layer 12 may not be formed.
　例えば、ＤＢＣにおいては、金属板を構成するＣｕと酸素（Ｏ）の共晶液相が接合に寄与し、このＯとしては、金属板中に含まれるものと、基板に含まれるものがあり、金属板中において、Ｏは不純物レベルで微量にのみ含まれる。このため、ＤＢＣによる接合強度は、金属板や基板の組成に影響を受け、前記のように、例えば基板が窒化物セラミックスで構成される場合には、高い接合強度を得ることが困難であった。 For example, in DBC, the eutectic liquid phase of Cu and oxygen (O) constituting the metal plate contributes to the bonding, and there are two types of O, one contained in the metal plate and the other contained in the substrate. In the metal plate, O is contained only in a trace amount at the impurity level. Therefore, the bonding strength by DBC is affected by the composition of the metal plate and the substrate, and as described above, when the substrate is made of nitride ceramics, for example, it is difficult to obtain high bonding strength. ..
　これに対して、ここで反応金属層１１として用いられるＴｉは、金属板２０を構成する主成分であるＣｕや、基板１０を構成するセラミックス材料中のＮ（窒化物の場合）やＯ（酸化物の場合）等と反応して合金層（接合層１５）を形成する。このため、基板１０を構成する材料が窒化物系、酸化物系のどちらであっても、安定して接合層１５が形成される。 On the other hand, Ti used here as the reactive metal layer 11 is Cu, which is the main component constituting the metal plate 20, and N (in the case of nitride) and O (oxidation) in the ceramic material constituting the substrate 10. (In the case of a product) and the like to form an alloy layer (bonding layer 15). Therefore, regardless of whether the material constituting the substrate 10 is a nitride-based material or an oxide-based material, the bonding layer 15 is stably formed.
　活性金属ろう材を用いた場合でも、同様に界面にＴｉが存在する。しかしながら、Ｔｉの含有量は１％程度と少ないため、状況は全く異なり、上記のような薄く強固な接合層１５のみによる接合は得られない。 Even when an active metal brazing material is used, Ti is also present at the interface. However, since the Ti content is as low as about 1%, the situation is completely different, and the above-mentioned thin and strong bonding layer 15 alone cannot be used for bonding.
　なお、上記の例では、反応金属層１１がＴｉ（純Ｔｉ）で構成されるものとしたが、上記と同様に接合層１５が形成される限りにおいて、反応金属層１１がＴｉ以外の材料を含有していてもよい。また、同様に基板１０側のＯ、Ｎ等や金属板２０側のＣｕと反応をすることができ、かつ上記の通りに基板１０側又は金属板２０側に薄く成膜が可能である限りにおいて、他の金属を反応金属層１１の主成分としてもよい。 In the above example, the reactive metal layer 11 is made of Ti (pure Ti), but as long as the bonding layer 15 is formed in the same manner as described above, the reactive metal layer 11 is made of a material other than Ti. It may be contained. Similarly, as long as it can react with O, N, etc. on the substrate 10 side and Cu on the metal plate 20 side, and as described above, a thin film can be formed on the substrate 10 side or the metal plate 20 side. Other metals may be used as the main component of the reaction metal layer 11.
　図２Ａは、窒化珪素（Ｓｉ３Ｎ４）で構成されたセラミックス基板上にＡｇ、ＣｕにＴｉが添加された活性金属ろう材を用いて銅（無酸素銅）で構成された金属板を接合して形成された回路基板の断面ＳＥＭ写真である。これに対して、図２Ｂは、本発明の実施例となる製造方法によって上記のセラミックス基板（基板１０）に上記の金属板（金属板１０）を接合して形成された回路基板の断面ＳＥＭ写真である。ここでは、反応金属層１１としては厚さ０．０５μｍのＴｉ、酸化防止層１２としては厚さ０．１μｍのＡｇが用いられた。 In FIG. 2A, a metal plate made of copper (oxygen-free copper) is joined to a ceramic substrate made of silicon nitride (Si 3 N 4 ) using an active metal brazing material in which Ag and Ti are added to Cu. It is a cross-sectional SEM photograph of the circuit board formed in the above. On the other hand, FIG. 2B is a cross-sectional SEM photograph of a circuit board formed by joining the metal plate (metal plate 10) to the ceramic substrate (board 10) by the manufacturing method according to the embodiment of the present invention. Is. Here, Ti having a thickness of 0.05 μm was used as the reactive metal layer 11, and Ag having a thickness of 0.1 μm was used as the antioxidant layer 12.
　活性金属ろう材を用いた図２Ａの場合には、厚さが１０μｍ程度の接合層が基板と金属板の境界で明確に確認できるが、実施例となる図２Ｂの場合には、接合層が確認できない。また、図２Ｂにおける金属板／基板界面の凹凸は、基板表面の凹凸をそのまま反映している。すなわち、図１Ｆにおける接合層１５は実際には非常に薄くなり、１μｍよりも大幅に薄くなる。あるいは、少なくともＳＥＭで明確に確認できる程度の厚さの接合層が形成されていることはない。このため、接合層の熱伝導率によらず、回路基板の放熱効率を高くすることができる。 In the case of FIG. 2A using the active metal brazing material, a bonding layer having a thickness of about 10 μm can be clearly confirmed at the boundary between the substrate and the metal plate, but in the case of FIG. 2B as an example, the bonding layer is I can't confirm. Further, the unevenness of the metal plate / substrate interface in FIG. 2B directly reflects the unevenness of the substrate surface. That is, the bonding layer 15 in FIG. 1F is actually very thin, and is significantly thinner than 1 μm. Alternatively, a bonding layer having a thickness that can be clearly confirmed by at least SEM is not formed. Therefore, the heat dissipation efficiency of the circuit board can be increased regardless of the thermal conductivity of the bonding layer.
　また、反応金属層１１を構成するＴｉの熱伝導率は金属板２０を構成するＣｕと比べて大幅に低い。このため、接合層１５中においてＴｉが反応金属層１１のまま厚く残存していると、接合層１５の実質的な熱伝導率が低下する。一方、接合に寄与するのは反応金属層１１におけるＴｉと金属板２０のＣｕ、基板１０中の金属元素等が反応して合金化した部分だけであるため、このように合金化した部分が形成される限りにおいて、反応金属層１１は薄いことが好ましく、ホットプレス工程後において反応金属層１１中のＴｉがそのままの状態で残存した部分が少ないことが好ましい。このため、図１Ｃにおける反応金属層１１の厚さは、１μｍ以下とすることが好ましい。この厚さが１μｍを超える場合には、回路基板の熱伝導率が低くなる。また、製造の際のスループットを向上させるためにも、スパッタリング法によって成膜される反応金属層１１、酸化防止層１２は薄いことが好ましい。一方、反応金属層１１の厚さをスパッタリング法による成膜で制御可能な厚さの下限（例えば０．０１μｍ程度）と設定した場合においても、強固な接合を得ることができる。また、反応金属層１１の厚さが０．０１μｍ未満である場合には、膜厚の制御が困難であるために、有効な膜厚が均一に得られないために十分な接合強度を得ることが困難となる場合がある。ただし、ろう材を塗布によって形成する場合と比べて、上記のように反応金属層１１等をスパッタリング法によって成膜する場合には、これらを十分に薄くすることができる。このため、反応金属層１１の厚さは０．０１～１μｍの範囲とすることが好ましい。 Further, the thermal conductivity of Ti constituting the reactive metal layer 11 is significantly lower than that of Cu constituting the metal plate 20. Therefore, if Ti remains thick as the reactive metal layer 11 in the bonding layer 15, the substantial thermal conductivity of the bonding layer 15 decreases. On the other hand, since it is only the portion of the reactive metal layer 11 that is alloyed by the reaction of Ti, the Cu of the metal plate 20, the metal element in the substrate 10, and the like, the portion that is alloyed in this way is formed. As long as it is performed, it is preferable that the reaction metal layer 11 is thin, and it is preferable that after the hot pressing step, there are few portions where Ti in the reaction metal layer 11 remains as it is. Therefore, the thickness of the reactive metal layer 11 in FIG. 1C is preferably 1 μm or less. When this thickness exceeds 1 μm, the thermal conductivity of the circuit board becomes low. Further, in order to improve the throughput during manufacturing, it is preferable that the reactive metal layer 11 and the antioxidant layer 12 formed by the sputtering method are thin. On the other hand, even when the thickness of the reactive metal layer 11 is set to the lower limit (for example, about 0.01 μm) of the thickness that can be controlled by film formation by the sputtering method, a strong bond can be obtained. Further, when the thickness of the reactive metal layer 11 is less than 0.01 μm, it is difficult to control the film thickness, so that an effective film thickness cannot be uniformly obtained, and sufficient bonding strength is obtained. Can be difficult. However, compared with the case where the brazing material is formed by coating, when the reactive metal layer 11 and the like are formed by the sputtering method as described above, these can be made sufficiently thin. Therefore, the thickness of the reactive metal layer 11 is preferably in the range of 0.01 to 1 μm.
　また、ホットプレス工程を行う際には、Ｃｕで構成された金属板２０とセラミックス材料で構成された基板１０の熱膨張差が大きくなるため、金属板２０と基板１０の間には大きな剪断歪みが発生する。この剪断歪を接合界面（接合層１５）のみが受け持つことは、接合層１５が薄い場合には困難であり、接合層１５による高い接合強度を得ることが困難である。ホットプレス工程における圧力や温度を調整することにより、金属板２０の収縮、膨張を拘束することができるため、この剪断歪を低減することができる。すなわち、上記の製造方法においては、ホットプレス工程における圧力、温度の設定が特に重要である。この際、図１Ｅで用いられるスペーサ１１０の熱膨張係数を、基板１０の熱膨張係数と近づけることで、特にこの剪断歪を低減することができる。このようなスペーサ１１０の材料としてＣＩＰ（Ｃｏｌｄ　Ｉｓｏｓｔａｔｉｃ　Ｐｒｅｓｓ）材カーボン板、耐熱板、基板１０と同様のセラミック板を用いることが特に好ましい。 Further, when the hot press process is performed, the difference in thermal expansion between the metal plate 20 made of Cu and the substrate 10 made of ceramic material becomes large, so that a large shear strain is generated between the metal plate 20 and the substrate 10. Occurs. It is difficult for the bonding interface (bonding layer 15) to take charge of this shear strain only when the bonding layer 15 is thin, and it is difficult to obtain high bonding strength by the bonding layer 15. By adjusting the pressure and temperature in the hot press process, the shrinkage and expansion of the metal plate 20 can be restrained, so that this shear strain can be reduced. That is, in the above manufacturing method, the setting of pressure and temperature in the hot pressing process is particularly important. At this time, by bringing the thermal expansion coefficient of the spacer 110 used in FIG. 1E close to the thermal expansion coefficient of the substrate 10, this shear strain can be particularly reduced. As a material for such a spacer 110, it is particularly preferable to use a CIP (Cold Isostatic Press) material carbon plate, a heat-resistant plate, and a ceramic plate similar to the substrate 10.
　以下に、上記の製造方法によって実際に回路基板を製造し、金属板の接合強度を測定した結果について説明する。ここで、基板１０の大きさは１９０ｍｍ×１３８ｍｍ×０．３２ｍｍとされ、金属板２０の大きさは１９０ｍｍ×１３８ｍｍとされた。 The results of actually manufacturing the circuit board by the above manufacturing method and measuring the bonding strength of the metal plate will be described below. Here, the size of the substrate 10 was 190 mm×138 mm×0.32 mm, and the size of the metal plate 20 was 190 mm×138 mm.
　初めに、反応金属層１１としてＴｉを用い、その膜厚を変えてホットプレス条件は一定として接合強度を測定した。Ｔｉの成膜はＤＣスパッタリングにより行い、そのパワーは４００Ｗとし、成膜時間のみを変えて複数種類の膜厚を設定した。酸化防止層１２は膜厚０．１μｍのＡｇとされ、反応金属層１１、酸化防止層１２は図１Ｃのとおり、基板１０側に形成された。ホットプレス条件は８００℃、１０ＭＰａとされた。金属板２０は０．３ｍｍの銅（無酸素銅）板、基板１０はＳｉＮとされ、スペーサ１１０はＣＩＰ材カーボン板とされた。Ｔｉの膜厚は、成膜前後の重量から算出された。接合強度は、接合後の構造（回路基板）における金属板２０を２ｍｍ角のサイズにエッチング加工し、その表面に銅のワイヤをハンダ付けし、銅ワイヤを鉛直方向に引っ張って剥離する荷重を測定し、面積（４ｍｍ２)で割ることで、算出した。結果を表１に示す。 First, Ti was used as the reaction metal layer 11, the thickness was changed, and the hot pressing conditions were kept constant to measure the bonding strength. The Ti film was formed by DC sputtering, the power was set to 400 W, and only a film forming time was changed to set a plurality of kinds of film thicknesses. The antioxidant layer 12 was made of Ag having a thickness of 0.1 μm, and the reactive metal layer 11 and the antioxidant layer 12 were formed on the substrate 10 side as shown in FIG. 1C. The hot press conditions were 800° C. and 10 MPa. The metal plate 20 was a 0.3 mm copper (oxygen-free copper) plate, the substrate 10 was SiN, and the spacer 110 was a CIP carbon plate. The film thickness of Ti was calculated from the weight before and after the film formation. For the bonding strength, the metal plate 20 in the structure (circuit board) after bonding is etched to a size of 2 mm square, a copper wire is soldered to the surface, and the load of pulling the copper wire in the vertical direction to peel it off is measured. Then, it was calculated by dividing by the area (4 mm 2 ). The results are shown in Table 1.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　この結果より、反応金属層１１がない（膜厚０μｍ）場合と比べて、反応金属層１１を形成することにより、一様に２０Ｎ／ｍｍ２以上の高い接合強度が得られることが確認できる。 From this result, it can be confirmed that a higher bonding strength of 20 N / mm 2 or more can be uniformly obtained by forming the reactive metal layer 11 as compared with the case where the reactive metal layer 11 is not present (thickness 0 μm).
　次に、ホットプレスの条件（温度、圧力）を変えて、接合強度を測定した。ここで、反応金属層（Ｔｉ）の膜厚は０．０５μｍ、酸化防止層１２は膜厚０．１μｍのＡｇとされ、反応金属層１１、酸化防止層１２は図１Ｃのとおり、基板１０側に形成された。金属板２０は０．３ｍｍ厚の銅板、基板１０はＳｉＮとされ、スペーサ１１０はＣＩＰ材カーボン板とされた。結果を表２に示す。 Next, the joint strength was measured by changing the hot press conditions (temperature, pressure). Here, the film thickness of the reactive metal layer (Ti) is 0.05 μm, the antioxidant layer 12 is Ag with a film thickness of 0.1 μm, and the reactive metal layer 11 and the antioxidant layer 12 are on the substrate 10 side as shown in FIG. 1C. Formed in. The metal plate 20 was a 0.3 mm thick copper plate, the substrate 10 was SiN, and the spacer 110 was a CIP carbon plate. The results are shown in Table 2.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　この結果より、ホットプレス工程を温度６００℃以上、圧力１ＭＰａ～１００ＭＰａで行うことにより、一様に２０Ｎ／ｍｍ２以上の高い接合強度が得られることが確認できる。 From this result, it can be confirmed that by performing the hot pressing step at a temperature of 600° C. or higher and a pressure of 1 MPa to 100 MPa, a high bonding strength of 20 N/mm 2 or more can be uniformly obtained.
　また、基板１０として、ベリリア（ＢｅＯ）を用いて同様に回路基板を形成した。反応金属層１１として０．０５μｍのＴｉ、酸化防止層１２として０．０５μｍのＡｇを用い、ホットプレスを８５０℃、１０ＭＰａで行った。基板１０の材料が異なるために、上記と同様の接合強度の測定は困難であったが、上記のような剥離後の界面の写真を図３に示す。ここでは、基板１０を構成するＢｅＯ自身が破壊されているため、少なくとも接合強度が基板１０の破壊強度を超えていることが確認できる。このため、上記の製造方法は、ＢｅＯ基板を用いた場合においても有効である。 Further, as the substrate 10, beryllium (BeO) was used to form a circuit board in the same manner. Hot pressing was performed at 850 ° C. and 10 MPa using 0.05 μm Ti as the reactive metal layer 11 and 0.05 μm Ag as the antioxidant layer 12. It was difficult to measure the bonding strength similar to the above because the material of the substrate 10 was different, but FIG. 3 shows a photograph of the interface after peeling as described above. Here, since BeO itself constituting the substrate 10 is destroyed, it can be confirmed that at least the bonding strength exceeds the fracture strength of the substrate 10. Therefore, the above manufacturing method is effective even when a BeO substrate is used.
　上記の製造方法における基板１０としては、ＳｉＮ，ＢｅＯの他に、Ａｌ２Ｏ３、ＡｌＮ等を用いることができる。これらの材料は、いずれも高い絶縁性をもち、回路基板の材料として好ましく用いられる。また、構成元素として、反応金属層１１と反応をするＯ、Ｎが含まれる。 As the substrate 10 in the above manufacturing method, Al 2 O 3 , AlN, or the like can be used in addition to SiN and BeO. All of these materials have high insulation properties and are preferably used as materials for circuit boards. In addition, O and N that react with the reactive metal layer 11 are included as constituent elements.
　これに対応して、反応金属層１１を構成する材料としては、上記のＴｉの他に、Ｚｒを用いることもできる。Ｚｒも、Ｔｉと同様にスパッタリング法によって上記の範囲の膜厚で容易に製膜することができる。 Correspondingly, Zr can be used as the material constituting the reactive metal layer 11 in addition to the above Ti. Like Ti, Zr can be easily formed with a film thickness in the above range by a sputtering method.
　また、金属板２０として、上記の例では純銅（無酸素銅）製のものが用いられたが、少なくとも銅を主成分とするものであれば上記の製造方法が同様に有効であることは明らかである。このため、銅合金を上記の金属板２０として用いることができる。 Further, as the metal plate 20, a metal plate 20 made of pure copper (oxygen-free copper) was used in the above example, but it is clear that the above manufacturing method is similarly effective as long as it contains at least copper as a main component. Is. Therefore, a copper alloy can be used as the metal plate 20.
１０　基板
１１　反応金属層
１２　酸化防止層
１５　接合層
２０　金属板
１００　ホットプレス基台
１１０　スペーサ 10 Substrate 11 Reactive Metal Layer 12 Antioxidation Layer 15 Bonding Layer 20 Metal Plate 100 Hot Press Base 110 Spacer

Claims (9)

  1. 　絶縁性の基板の表面に銅（Ｃｕ）又は銅合金で構成された金属板が接合された構成を具備する回路基板の製造方法であって、
    　前記基板、前記金属板のうちの少なくともいずれかの表面に、前記基板及び前記金属板と反応をする金属を含む反応金属層を成膜する反応金属層成膜工程と、
    　前記反応金属層が前記基板と前記金属板との間にある形態で前記基板と前記金属板とを積層し、非酸化雰囲気中で、前記反応金属層と前記金属板及び前記基板との間で反応が生じる温度で前記基板と前記金属板の間に圧力を印加するホットプレス工程と、
    　を具備することを特徴とする回路基板の製造方法。     A method for manufacturing a circuit board, comprising a structure in which a metal plate made of copper (Cu) or a copper alloy is joined to the surface of an insulating substrate,
    A reaction metal layer forming step of forming a reaction metal layer containing a metal that reacts with the substrate and the metal plate on at least one surface of the substrate and the metal plate;
    The substrate and the metal plate are laminated in a form in which the reactive metal layer is between the substrate and the metal plate, and in a non-oxidizing atmosphere, between the reactive metal layer and the metal plate and the substrate. A hot pressing step of applying pressure between the substrate and the metal plate at a temperature at which a reaction occurs,
    A method for manufacturing a circuit board, which comprises the above.
  2. 　前記反応金属層はチタン（Ｔｉ）を含むことを特徴とする請求項１に記載の回路基板の製造方法。 The method for manufacturing a circuit board according to claim 1, wherein the reactive metal layer contains titanium (Ti).
  3. 　前記反応金属層の厚さを０．０１～１μｍの範囲とすることを特徴とする請求項２に記載の回路基板の製造方法。 The method for manufacturing a circuit board according to claim 2, wherein the thickness of the reactive metal layer is in the range of 0.01 to 1 μm.
  4. 　前記基板はアルミナ、窒化珪素、窒化アルミニウム、ベリリアのうちのいずれかを主成分とする材料で構成されたことを特徴とする請求項１から請求項３までのいずれか１項に記載の回路基板の製造方法。 The circuit board according to any one of claims 1 to 3, wherein the substrate is made of a material containing any one of alumina, silicon nitride, aluminum nitride, and beryllia as a main component. Manufacturing method.
  5. 　前記ホットプレス工程を、温度６００℃以上の範囲、圧力１ＭＰａ以上の範囲で行うことを特徴とする請求項１から請求項４までのいずれか１項に記載の回路基板の製造方法。 The method for manufacturing a circuit board according to any one of claims 1 to 4, wherein the hot pressing step is performed in a temperature range of 600 ° C. or higher and a pressure range of 1 MPa or higher.
  6. 　前記反応金属層成膜工程において、前記反応金属層の上に、前記反応金属層とは異なる材料で構成された酸化防止層を形成することを特徴とする請求項１から請求項５までのいずれか１項に記載の回路基板の製造方法。 Any of claims 1 to 5, wherein in the reaction metal layer film forming step, an antioxidant layer made of a material different from that of the reaction metal layer is formed on the reaction metal layer. 2. A method for manufacturing a circuit board according to item 1.
  7. 　前記酸化防止層は金（Ａｕ）、銀（Ａｇ）、銅（Ｃｕ）、錫（Ｓｎ）、白金（Ｐｔ）、アルミニウム（Ａｌ）のいずれかを含むことを特徴とする請求項６に記載の回路基板の製造方法。 The sixth aspect of claim 6, wherein the antioxidant layer contains any one of gold (Au), silver (Ag), copper (Cu), tin (Sn), platinum (Pt), and aluminum (Al). Circuit board manufacturing method.
  8. 　前記反応金属層成膜工程はスパッタリング法により行われることを特徴とする請求項１から請求項７までのいずれか１項に記載の回路基板の製造方法。 The method for manufacturing a circuit board according to any one of claims 1 to 7, wherein the step of forming the reactive metal layer is performed by a sputtering method.
  9. 　前記ホットプレス工程において、前記金属板はスペーサを介して加圧され、前記スペーサはカーボン板、耐熱ガラス板、セラミックス板のいずれかで構成されたことを特徴とする請求項１から請求項８までのいずれか１項に記載の回路基板の製造方法。 Claims 1 to 8 are characterized in that, in the hot pressing step, the metal plate is pressed through a spacer, and the spacer is composed of any one of a carbon plate, a heat-resistant glass plate, and a ceramic plate. The method for manufacturing a circuit board according to any one of 1.
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Publication number Priority date Publication date Assignee Title
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60177635A (en) * 1984-02-24 1985-09-11 Toshiba Corp Manufacture of good heat conductive substrate
JPH02177463A (en) * 1988-12-28 1990-07-10 Mitsubishi Electric Corp Manufacture of ceramic-metal composite board
JP2007227867A (en) * 2006-01-27 2007-09-06 Kyocera Corp Heat dissipation substrate and semiconductor device using the same
JP2012200730A (en) * 2011-03-23 2012-10-22 Hitachi Metals Ltd Joining method, joining fixture, and circuit board
JP2018140929A (en) * 2017-02-28 2018-09-13 三菱マテリアル株式会社 Copper-ceramic bonded body, insulating circuit board, method for manufacturing copper-ceramic bonded body, and method for manufacturing insulating circuit board

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63252975A (en) * 1987-04-09 1988-10-20 古河電気工業株式会社 Method of joining ceramic material to metal member
JPS649878A (en) * 1987-07-02 1989-01-13 Agency Ind Science Techn Bonding between silicon nitride ceramics and metal

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60177635A (en) * 1984-02-24 1985-09-11 Toshiba Corp Manufacture of good heat conductive substrate
JPH02177463A (en) * 1988-12-28 1990-07-10 Mitsubishi Electric Corp Manufacture of ceramic-metal composite board
JP2007227867A (en) * 2006-01-27 2007-09-06 Kyocera Corp Heat dissipation substrate and semiconductor device using the same
JP2012200730A (en) * 2011-03-23 2012-10-22 Hitachi Metals Ltd Joining method, joining fixture, and circuit board
JP2018140929A (en) * 2017-02-28 2018-09-13 三菱マテリアル株式会社 Copper-ceramic bonded body, insulating circuit board, method for manufacturing copper-ceramic bonded body, and method for manufacturing insulating circuit board

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