JP2014011423A - Substrate for power module and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a less expensive substrate for power modules capable of accurately positioning a semiconductor element when the semiconductor element is bonded on a circuit copper plate with a bonding material and preventing the semiconductor element from being positionally deviated by the bonding material flow, and a method for manufacturing the substrate.SOLUTION: A substrate 10 for power modules includes: a circuit copper plate 12 for mounting a semiconductor element 20 on a principal surface of a ceramic substrate 11 and 11a to form an electrical conductive state; and a heat dissipation copper plate 13 for dissipating heat generated from a semiconductor element 20 to the other principal surface. An upper surface of the circuit copper plate 12 having the semiconductor element 20 bonded through a bonding material 24a has a recessed pattern 14 having a width part having a size of 0.05 mm or more and a depth of more than 0 mm and 80% or less of the thickness of the circuit copper plate and covered with the semiconductor element 20 which straddles at least a part of the width part.

Description

  The present invention provides a power module substrate in which a circuit copper plate is bonded to one main surface of both surfaces of a ceramic substrate, and a heat dissipation copper plate is bonded to the other main surface, and an electronic component is mounted on the circuit copper plate via a bonding material, and It relates to the manufacturing method.

  Conventionally, a semiconductor element that generates high heat, such as a power transistor with higher power, higher speed, and higher integration, can be mounted, and heat generated from the semiconductor element can be quickly dissipated to maintain the reliability of the semiconductor element. Therefore, the power module substrate is used for consumer equipment and in-vehicle use such as automobiles and electric cars. For such a power module substrate, one ceramic substrate or a large ceramic substrate in which a plurality of ceramic substrates can be arranged in a matrix is usually used. To this ceramic substrate, a direct bonding method in which a copper plate that is approximately the same as or slightly smaller than the size of the ceramic substrate is directly heat-bonded using the melting point of copper, or heat bonding is performed using an active metal brazing. Joined by active metal brazing method. Then, the ceramic substrate with the copper plate affixed to almost the entire surface is generated from the semiconductor element and the patterned circuit copper plate for mounting a semiconductor element on each main surface and forming an electrically conductive state by etching. A heat-dissipating copper plate is formed for heat transfer and heat dissipation. In addition, a power module substrate assembly in which a plurality of power module substrates each having a pair of a circuit copper plate and a heat dissipation copper plate are arranged in a matrix on a large ceramic substrate is formed with a dividing groove for dividing into individual pieces. There is a case.

  In the individual power module substrate, a semiconductor element is bonded with a bonding material onto a predetermined portion of the copper plate on the circuit copper plate side. Further, the power module substrate is configured such that the external connection terminals are bonded with a bonding material on a copper plate different from the copper plate with the semiconductor element bonded with the bonding material. Then, the power module substrate forms an electrical conduction circuit by connecting the semiconductor element and another portion of the copper plate with a bonding wire, and a high voltage and high current is supplied to the semiconductor element via the external connection terminal. To be able to flow. In addition, this power module substrate has a thermal conductivity in order to quickly dissipate heat from the semiconductor element generated by the flow of high voltage and high current from the circuit copper plate side using copper having good thermal conductivity. Heat is transferred to the heat radiating copper plate side using good copper, and is usually radiated from a heat sink plate joined to the heat radiating copper plate with a bonding material or the like.

  However, in the power module substrate, since the semiconductor element is bonded to the predetermined portion of the copper plate on the circuit copper plate side with a bonding material, an extra bonding material is attached to the outside of the semiconductor element when the bonding material is attached, There has been a problem of flowing out on the ceramic substrate.

  Therefore, a conventional power module substrate and a manufacturing method thereof include a power module substrate for providing a bank around a bonding portion of a copper plate to which a semiconductor element is bonded by a bonding material, and for preventing the bonding material from flowing. Has been proposed (see, for example, Patent Document 1 and Patent Document 2).

  Further, a conventional power module substrate is formed by bonding a metal circuit board to the upper surface of the ceramic substrate based on the name of the invention of a ceramic circuit substrate, and a semiconductor element via a bonding material on the upper surface of the metal circuit plate. In a ceramic circuit board on which is mounted, a metal circuit board is proposed in which a frame-like groove is formed on the upper surface of which an outer peripheral edge of a semiconductor element is located between an inner periphery and an outer periphery (for example, And Patent Document 3).

JP-A-10-242330 JP-A-10-242331 JP 2004-119568 A

However, the conventional power module substrate and the manufacturing method thereof as described above have the following problems.
(1) Although the power module substrate as disclosed in Japanese Patent Laid-Open No. 10-242330 and Japanese Patent Laid-Open No. 10-242331 can mount the semiconductor element on the semiconductor element mounting portion with good positioning, the semiconductor element The position where the semiconductor element is joined is shifted by the solder that flows out as the flux in the solder paste, which is a joining material at the time of joining, liquefies and spreads wet. In addition, this power module substrate prevents the solder from flowing out of the bank because the flux in the solder paste, which is the bonding material when joining the semiconductor elements, is liquefied and spreads out wet, and the solder that flows out is blocked by the bank. However, the solder that has flowed out may overflow into the bank frame and reach the upper surface of the semiconductor element, causing a defect in the semiconductor element.
(2) Although the power module substrate as disclosed in Japanese Patent Application Laid-Open No. 2004-119568 can mount the semiconductor element on the semiconductor element mounting portion with good positioning, the outer periphery of the semiconductor element has a frame-shaped groove. Since it is located between the inner periphery and the outer periphery, the bonding material that has flowed into the groove may reach the upper surface of the semiconductor element, causing a defect in the semiconductor element.
(3) A method for manufacturing a power module substrate as disclosed in JP-A-10-242330, JP-A-10-242331, and JP-A-2004-119568 includes a circuit copper plate, a bank, Since the grooves are formed by etching, cutting, or the like, the production is complicated and difficult, and the production takes time, which increases the cost of the power module substrate.

  The present invention has been made in view of such circumstances, and can accurately position a semiconductor element on a circuit copper plate when bonding the bonding material, and can prevent a mounting position shift of the semiconductor element due to the bonding material flow. An object of the present invention is to provide a power module substrate and a manufacturing method thereof.

  A power module substrate according to the present invention that meets the above-described object is generated from a circuit copper plate for forming an electrically conductive state by mounting a semiconductor element on one main surface of a ceramic substrate and a semiconductor element on the other main surface. In a power module substrate having a heat dissipating copper plate for dissipating heat, a circuit element on which a semiconductor element is bonded via a bonding material has a width part size of 0.05 mm or more and a depth exceeding 0 circuit. It has a concave pattern that is 80% or less of the thickness of the copper plate and is covered so that the semiconductor element straddles at least a part of the width portion.

  The method for manufacturing a power module substrate according to the present invention that meets the above-described object includes mounting a semiconductor element on one main surface by mounting the copper plate on each of the two main surfaces of the ceramic substrate and heat-bonding, and then etching the copper plate. In the method of manufacturing a power module substrate, a circuit copper plate for forming an electrically conductive state and a heat dissipating copper plate for dissipating heat generated from the semiconductor element on the other main surface are provided. The copper plate heat-bonded to each of the copper plate for forming the circuit copper plate has a desired concave pattern pattern as an opening, the first etching resist mask made of the desired circuit copper plate pattern, and the copper plate for forming the heat dissipation copper plate A step of forming a second etching resist mask comprising a desired heat dissipation copper plate pattern, and from the first and second etching resist masks The process of forming the 3rd etching resist mask which blocks the bottomed hole part of the copper plate exposed from the opening of the concave pattern pattern of the 1st etching resist mask, after etching the copper plate to take out to the middle of the thickness of a copper plate And removing the first, second, and third etching resist masks after etching the copper plate exposed from the first, second, and third etching resist masks until the ceramic substrate is exposed to the outside. Have.

  In the above method for manufacturing a power module substrate, the ceramic substrate is made of aluminum oxide, aluminum nitride, or aluminum oxide containing zirconia, and the copper plate is directly bonded to each of both main surfaces of the ceramic substrate, or by active metal brazing material bonding. It is preferable to heat-join.

  In the above power module substrate, the width of the width portion is 0.05 mm or more and the depth is more than 0 on the upper surface of the circuit copper plate to which the semiconductor element is bonded via the bonding material, and 80% or less with respect to the thickness of the circuit copper plate. And having a concave pattern that covers at least a portion of the width portion so that the semiconductor element straddles, so that the semiconductor element can be accurately positioned and mounted by this concave pattern, and a bonding material paste at the time of semiconductor element bonding The lower surface of the semiconductor element can be firmly bonded to the circuit copper plate with the bonding material that has flowed out when the flux inside is liquefied and spreads wet, and the excess flux that liquefies and spreads when the flux in the bonding material paste liquefies below the semiconductor element The semiconductor element is desired by allowing the bonding material to flow into the concave pattern and restricting the wetting and spreading of the excess bonding material to the periphery of the semiconductor element. Exactly location, it is possible to provide a power module substrate can be and firmly bonded. In this power module substrate, the concave pattern has a width portion of 0.05 mm or more and a depth of more than 0 and less than 80% of the thickness of the circuit copper plate. It is possible to provide a power module substrate provided with a free-form concave pattern such as a linear shape, a polygonal shape, or a circular shape.

  In the power module substrate manufacturing method described above, a desired pattern for a copper circuit board is formed by opening a desired concave pattern pattern on a copper sheet for forming a circuit copper sheet of a copper sheet heat-bonded to both main surfaces of the ceramic substrate. A first etching resist mask comprising: a step of forming a second etching resist mask comprising a desired heat dissipation copper plate pattern on the copper plate for forming the heat dissipation copper plate; and exposure from the first and second etching resist masks. Forming a third etching resist mask for closing the bottomed hole portion of the copper plate exposed from the opening of the concave pattern pattern of the first etching resist mask after etching the copper plate to the middle of the thickness of the copper plate; The ceramic substrate is exposed to the outside of the copper plate exposed from the first, second, and third etching resist masks. And then removing the first, second and third etching resist masks, so that each of the main surfaces of the ceramic substrate is provided with a concave pattern having a desired size and shape. It is possible to provide a manufacturing method capable of easily forming an inexpensive power module substrate on which a circuit copper plate and a solid heat radiating copper plate are provided simultaneously.

  In particular, in this method for manufacturing a power module substrate, the ceramic substrate is made of aluminum oxide, aluminum nitride, or aluminum oxide containing zirconia, and a copper plate is directly bonded to each of the two main surfaces of the ceramic substrate or by active metal brazing material bonding. Since it is heat-bonded, the copper plate bonded to the ceramic substrate can be easily etched, and an inexpensive power module substrate provided with a circuit copper plate having a concave pattern having a desired size and shape and a heat-dissipating copper plate at the same time. A manufacturing method that can be easily formed can be provided.

(A), (B) is explanatory drawing of the board | substrate for power modules which concerns on one embodiment of this invention, respectively. It is explanatory drawing when mounting a semiconductor element on the board | substrate for power modules. (A)-(E) is explanatory drawing of the manufacturing method of the board | substrate for power modules which concerns on one embodiment of this invention, respectively.

Next, embodiments of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention.
A power module substrate according to an embodiment of the present invention will be described with reference to FIGS. 1 (A) to 1 (C) and FIG. FIG. 1A is a perspective view of a power module substrate assembly in which a plurality of power module substrates are assembled. FIG. 1B is a vertical cross-sectional view taken along line AA ′ in FIG. FIG. 1C is a perspective view of the power module substrate. FIG. 2 is an explanatory view in a cross-sectional view when a semiconductor element is mounted on a power module substrate.

  One of the above power module substrates 10 may be fabricated on a fired ceramic substrate 11 having a predetermined size. Usually, as shown in FIGS. 1A and 1B, firing is performed. A power module substrate assembly 30 is formed in which a plurality of power module substrates 10 are arranged and assembled on a finished large ceramic substrate 11a. 1C, finally, the power module substrate 10 is divided by the large ceramic substrate 11a portion of the power module substrate assembly 30 to have a predetermined size. The power module substrate 10 is used.

  The power module substrate 10 includes a circuit copper plate 12 on the upper surface side, which is one main surface of the ceramic substrate 11, and a heat dissipation copper plate 13 having a solid pattern on the lower surface side, which is the other main surface of the ceramic substrate 11. Have. As shown in FIG. 2, the power module substrate 10 is mounted with a semiconductor element 20 that generates high heat, such as a power transistor, on the circuit copper plate 12 at a predetermined position, or external connection terminals on the circuit copper plate 12 at other predetermined positions. 21 is joined, and furthermore, the semiconductor element 20 and another circuit copper plate 12 on which the semiconductor element 20 is not mounted are connected by a bonding wire 22 so that an electrically conductive state can be formed. The power module substrate 10 further dissipates heat by joining a heat-dissipating copper plate 13 for promptly transferring and dissipating heat generated from the semiconductor element 20 joined to the upper surface of the circuit copper plate 12 to a heat sink plate 23 or the like. It can be further promoted.

  The power module substrate 10 has a concave pattern 14 that is covered on the upper surface of the circuit copper plate 12 to which the semiconductor element 20 is bonded via the bonding material 24 so that the semiconductor element 20 straddles at least a part of the width of the pattern. have. The concave pattern 14 is not particularly limited in shape, for example, a quadrilateral that can be covered so that the semiconductor element 20 straddles part or all of the pattern, a polygon, It may be a pattern having a ring-shaped groove width portion such as a circular shape or a free shape. The concave pattern 14 is, for example, a straight line that can be covered so that the semiconductor element 20 straddles part or all of the pattern, a linear groove width portion such as a curve, a cross shape, It may be a pattern having crossed linear groove widths such as radial lines. Alternatively, the recessed pattern 14 may be, for example, a pattern including one or a plurality of crater-shaped holes wide enough to be covered so that the semiconductor element 20 straddles part or all of the pattern. .

  The concave pattern 14 provided on the upper surface of the circuit copper plate 12 can be used for positioning when the semiconductor element 20 is placed on the circuit copper plate 12, and the semiconductor element 20 can be accurately positioned on the circuit copper plate 12. it can. Further, the concave pattern 14 provided on the upper surface of the circuit copper plate 12 allows the flux in the cream solder provided on the circuit copper plate 12 to be bonded when the semiconductor element 20 is bonded to the circuit copper plate 12 via a bonding material 24, for example, solder. The liquefaction and wetting and spreading can be suppressed by flowing into the concave pattern 14, and the solder that is the bonding material 24 can be prevented from flowing out. The semiconductor element 20 is provided with an appropriate concave pattern 14 on the circuit copper plate 12, so that the region where the bonding material 24 spreads is limited, the regulating force of the position to be bonded works, and the required position is accurate. It can be firmly joined. Further, the bonding material 24, for example, solder flux does not exist on the circuit copper plate 12 outside the concave pattern 14, so that the region where the bonding material 24 spreads out is collected on the lower surface of the semiconductor element 20. Thus, it is possible to prevent creeping of the bonding material 24 to the upper surface side of the semiconductor element 20.

  The concave pattern 14 in the power module substrate 10 has a width portion having a width of 0.05 mm or more, a depth exceeding 0, and 80% or less with respect to the thickness of the circuit copper plate 12. It has become. The size of the width portion in the case of the pattern constituted by the grooves may vary depending on the location, but the size can be covered so that the semiconductor element 20 straddles at least a part of the width portion of the pattern. is necessary. Moreover, the width part dimension in the case of the pattern comprised by a crater-like hole needs that the semiconductor element 20 does not fall into a crater-like hole at least. When the width of the dent pattern 14 is less than 0.05 mm, the flux in the solder paste, for example, cream solder as in the case of solder tends to liquefy and spread. Therefore, since the flux gets wet and spreads over the concave pattern 14, the bonding material 24 flows out, and the creeping of the bonding material 24 to the upper surface side of the semiconductor element 20 cannot be prevented. Further, when the depth of the concave pattern 14 exceeds 80% with respect to the thickness of the circuit copper plate 12, the flow of the bonding material 24 into the concave pattern 14 increases, and the semiconductor element 20 is secured. Since the bonding material 24 is insufficient, the semiconductor element 20 cannot be firmly bonded to the upper surface of the circuit copper plate 12.

Next, a method for manufacturing the power module substrate 10 according to an embodiment of the present invention will be described with reference to FIGS.
The power module substrate 10 is produced by the method of forming the power module substrate 10 on the ceramic substrate 11 that has been prepared in advance, and a plurality of pieces on the large ceramic substrate 11a. In some cases, the power module substrate assembly 30 is formed as a power module substrate assembly 30. In this case, the power module substrate 10 is formed as the power module substrate assembly 30. I will explain it. 3A to 3E are cross-sectional views when the power module substrate 10 is manufactured as a power module substrate assembly 30 in which a plurality of power module substrates 10 are arranged and assembled on a large ceramic substrate 11a. .

  In this method for manufacturing the power module substrate 10, the thermal conductivity of the main surface of the fired large ceramic substrate 11a is approximately the same as the large ceramic substrate 11a and has a predetermined thickness on the upper surface side. A single copper plate 15, which is a high metal plate, and the same single copper plate 15 a as the above-described copper plate 15 having a predetermined thickness are placed on the lower surface side and are heat-bonded. Then, after the heat bonding, the power module substrate 10 is manufactured by etching the copper plates 15 and 15a with a predetermined etching solution and mounting the semiconductor element 20 on the upper surface side which is one main surface. The circuit copper plate 12 for forming the conductive state and the heat dissipating copper plate 13 for dissipating the heat generated from the semiconductor element 20 on the lower surface side which is the other main surface are provided so as to substantially correspond to the circuit copper plate 12. ing.

  As shown in FIG. 3 (A), in the method for manufacturing the power module substrate 10 according to the embodiment of the present invention, of the copper plates 15 and 15a that are heat-bonded to both main surfaces of the large-sized ceramic substrate 11a. A step of forming a first etching resist mask 16 in which a plurality of desired patterns for the circuit copper plate 12 are arranged with the desired pattern for the concave pattern 14 being formed in the copper plate 15 for forming the circuit copper plate 12 as an opening. ing. In addition, in this method of manufacturing the power module substrate 10, the copper plate 15 a for forming the heat-dissipating copper plate 13 among the copper plates 15 and 15 a thermally bonded to both main surfaces of the large ceramic substrate 11 a is desired. A step of forming a second etching resist mask 17 in which a plurality of patterns for the heat dissipation copper plate 13 are arranged. The etching resist masks 16 and 17 are formed by removing the oxide films on the upper surfaces of the copper plates 15 and 15a that are heat-bonded to both main surfaces of the large ceramic substrate 11a by acid cleaning, and then screening the copper resist plates 15 and 15a on the screens. A pattern is formed by printing or a photoresist method.

  Next, as shown in FIG. 3B, in the method for manufacturing the power module substrate 10, the copper plate 15 exposed from the first etching resist mask 16 and the copper plate 15a exposed from the second etching resist mask 17 are formed. Etching, so-called half-etching, is performed halfway through the thickness of each of the copper plates 15 and 15a. For this etching, an etching solution made of an aqueous solution containing 30 to 40% by weight of ferric chloride is usually used, and a predetermined time until the depth of the recessed pattern 14 reaches a desired depth is set to the first and first times. Etching is carried out by spraying an etching solution onto the copper plates 15 and 15a exposed from the second etching resist masks 16 and 17. As shown in FIG. 3C, in the method for manufacturing the power module substrate 10, after this half etching is performed, the copper plate exposed from the opening of the pattern for the concave pattern 14 of the first etching resist mask 16 is exposed. The third etching resist mask 18 for closing the 15 bottomed holes is formed on the first etching resist mask 16 by screen printing or a photoresist method in the same manner as described above.

  Next, as shown in FIG. 3D, in the method for manufacturing the power module substrate 10, the copper plates 15, 15a exposed from the first, second, and third etching resist masks 16, 17, 18 are made large. Etching is performed by spraying an etching solution in the same manner as described above for a predetermined time until the ceramic substrate 11a is exposed to the outside. Then, as shown in FIG. 3E, in the method for manufacturing the power module substrate 10, the first, second, and third etching resist masks 16, 17, and 18 are removed after the etching. It has a process. In the method for manufacturing the power module substrate 10, the first, second and third etching resist masks 16, 17 and 18 are removed, and then washed and dried to form the power module substrate assembly 30. Yes.

  In addition, when the power module substrate 10 is manufactured as a single substrate on the ceramic substrate 11, the semiconductor element 20 is mounted on a predetermined pattern of the circuit copper plate 12 to form electrical continuity. On the other hand, when a plurality of power module substrates 10 are arranged as the power module substrate assembly 30, the pressure formed by pressing the ceramic green sheet before firing with a cutting blade or the like. After dividing by the dividing groove 19 provided in at least one of both main surfaces of the large-sized ceramic substrate 11a as a groove | channel or the continuous dotted | punctate groove | channel formed by laser processing etc. after baking, the board | substrate for power modules of a single piece body 10 is mounted with a semiconductor element 20 to form electrical continuity. Alternatively, in the case of the power module substrate assembly 30, the ceramic green sheet before being fired in advance after the semiconductor element 20 is first mounted on each power module substrate 10 to form electrical continuity in each. It is made to divide | segment by the division groove | channel 19 provided in at least one of both the main surfaces of the large sized ceramic substrate 11a as a press groove | channel formed in this, or a continuous dotted groove | channel formed by laser processing etc. after baking. .

In the method for manufacturing the power module substrate 10 described above, the ceramic substrates 11 and 11a may be made of aluminum oxide (Al ₂ O ₃ ), aluminum nitride (AlN), or aluminum oxide containing zirconia. Since these ceramic substrates 11, 11a are excellent in insulation, heat resistance, thermal conductivity, substrate strength, etc., sufficient heat resistance against high voltage applied to the semiconductor element 20 and high heat from the semiconductor element 20, It can be used without problems with high thermal conductivity. Here, in order to produce the ceramic substrate 11, 11 a made of Al ₂ O ₃ which is an example of the ceramic substrate 11, 11 a, the powder is obtained by adding an appropriate amount of a sintering aid such as magnesia, silica, calcia to alumina powder. Then, a plasticizer such as dioctyl phthalate, a binder such as an acrylic resin, and a solvent such as toluene, xylene, and alcohols are added and kneaded sufficiently, and then defoamed to prepare a slurry having a viscosity of 2000 to 40000 cps. Yes. Then, this slurry is formed into a roll-like sheet having a thickness of about 0.64 mm by a doctor blade method or the like, cut into an appropriate size to produce a ceramic green sheet, and about 1550 ° C. in the atmosphere. The ceramic substrates 11 and 11a are produced by firing.

  Moreover, in order to produce ceramic substrates 11 and 11a made of AlN, which is an example of ceramic substrates 11 and 11a, a sintering aid is added to aluminum nitride powder, and a plasticizer, a binder, and a solvent are added to form a sheet. It is formed as a ceramic green sheet, cut into an appropriate size, and fired at a high temperature of about 1700 ° C. in a nitrogen atmosphere.

Furthermore, in order to produce the ceramic substrates 11 and 11a made of zirconia-containing aluminum oxide, which is an example of the ceramic substrates 11 and 11a, the main component aluminum oxide is in the range of 70 to 97 wt%, and zirconia (ZrO ₂ ) is added thereto. Is added in the range of 2 to 29.9 wt%, and one or more sintering aids of yttria, calcia, magnesia, and ceria are added in the range of 0.1 to 2 wt%, and the plasticizer, binder, and For example, a sheet-like ceramic green sheet having a thickness of 0.25 mm is formed by adding a solvent. The ceramic green sheet is cut into an appropriate size and fired at about 1550 ° C. in the atmosphere to produce the ceramic substrates 11 and 11a. The ceramic substrates 11 and 11a made of a fired body in which Al ₂ O ₃ is the main component and ZrO ₂ in the above ratio is added to the Al ₂ O ₃ single substrate while maintaining the same thermal conductivity as the Al ₂ O ₃ single substrate. substrate strength can be enhanced greatly, especially bending strength (in _Al 2 _{O 3} alone, 3.1 MPa ^{· m 0.5,} the zirconia alumina ceramic, 4.4MPa ^{· m 0.5).} In addition, by adding at least one of yttria, calcia, magnesia, and ceria, the toughness of the ZrO ₂ crystal grains can be improved while suppressing the firing temperature of the substrate to the same level as that of the substrate of Al ₂ O ₃ alone. Can do. As a result, although the ceramic substrates 11 and 11a have lower thermal conductivity than the AlN substrate, the thickness can be reduced to compensate for the lower thermal conductivity, which is superior to the Al ₂ O ₃ single substrate. It can have excellent heat dissipation comparable to an AlN substrate.

In the method for manufacturing the power module substrate 10 described above, the copper plates 15 and 15a may be directly bonded to each of the main surfaces of the ceramic substrates 11 and 11a or heat bonded by active metal brazing material bonding. In this direct bonding method, the copper plates 15 and 15a whose surfaces are oxidized in advance are brought into contact with the surfaces of the ceramic substrates 11 and 11a and fired in a nitrogen atmosphere until the melting point of copper oxide (1083 ° C.) is reached. In this method, the Cu—O eutectic liquid phase generated by the reaction between copper and a small amount of oxygen is heated and bonded directly to the ceramic substrates 11 and 11a as a binder. When the ceramic substrates 11 and 11a are made of AlN, it is necessary to form an oxide film on the surfaces of the ceramic substrates 11 and 11a, that is, to make the AlN surface Al ₂ O ₃ .

  The active metal brazing material joining method uses an active metal brazing material in which a so-called active metal having extremely high reactivity such as titanium, zirconium, beryllium or the like is added to an Ag-Cu brazing filler metal or the like. In this method, the ceramic substrates 11 and 11a and the copper plates 15 and 15a are joined. In this method of joining, first, a paste made of an active metal brazing material is applied to the respective surfaces of the ceramic substrates 11 and 11a, and the copper plates 15 and 15a whose surfaces have been previously oxidized are brought into contact with each other, and about 750 are contacted. This is a method of directly bonding to the ceramic substrates 11 and 11a by heating at about 850 ° C. and utilizing the strength of affinity with oxygen such as titanium. When the ceramic substrates 11 and 11a are made of zirconia-based alumina ceramic, the active metal brazing material contains, for example, one or more of zirconium, titanium, hydrogen fluoride, and niobium in Ag-Cu-based brazing. Can be used, and by increasing the affinity for the ceramic substrates 11 and 11a, the bonding reaction strength can be increased and strong bonding can be achieved.

  The power module substrate and the manufacturing method thereof according to the present invention are mounted with a semiconductor element that generates a large amount of heat through a high voltage flow. For example, the power module substrate for use in an inverter or an automobile component, and the like It can be used for manufacturing methods.

  10: Power module substrate, 11, 11a: Ceramic substrate, 12: Circuit copper plate, 13: Heat dissipation copper plate, 14: Recessed pattern, 15, 15a: Copper plate, 16: First etching resist mask, 17: Second Etching resist mask, 18: third etching resist mask, 19: dividing groove, 20: semiconductor element, 21: external connection terminal, 22: bonding wire, 23: heat sink plate, 24: bonding material, 30: power module substrate Aggregation

Claims (3)

A power module having a circuit copper plate for mounting a semiconductor element on one main surface of a ceramic substrate to form an electrically conductive state, and a heat dissipation copper plate for dissipating heat generated from the semiconductor element on the other main surface In the substrate for
The upper surface of the circuit copper plate to which the semiconductor element is bonded via a bonding material has a width portion size of 0.05 mm or more and a depth of more than 0 and 80% or less with respect to the thickness of the circuit copper plate, at least A power module substrate having a concave pattern that covers the semiconductor element so as to straddle a part of the width portion. A copper plate is placed on each of the two main surfaces of the ceramic substrate and heated and joined, and then the copper plate is etched to mount a semiconductor element on one main surface to form an electrically conductive state, and the other In the method for manufacturing a power module substrate, a heat dissipating copper plate for dissipating heat generated from the semiconductor element on the main surface of
The first etching comprising the desired pattern for the circuit copper plate, wherein the desired copper pattern for forming the circuit copper plate has an opening as a desired pattern for the concave pattern of the copper plate heat-bonded to both main surfaces of the ceramic substrate. Forming a resist mask and a second etching resist mask made of the desired heat dissipation copper plate pattern on the copper plate for forming the heat dissipation copper plate;
The copper plate exposed from the first and second etching resist masks is etched to the middle of the thickness of the copper plate, and then exposed from the opening of the concave pattern pattern of the first etching resist mask. Forming a third etching resist mask for closing the bottomed hole portion of the copper plate;
After etching the copper plate exposed from the first, second, and third etching resist masks until the ceramic substrate is exposed to the outside, the first, second, and third etching resist masks are removed. And a process for producing a power module substrate.   3. The method for manufacturing a power module substrate according to claim 2, wherein the ceramic substrate is made of aluminum oxide, aluminum nitride, or aluminum oxide containing zirconia, and the copper plate is directly bonded to each of both main surfaces of the ceramic substrate, or activated. A method for manufacturing a power module substrate, characterized by being heat-bonded by metal brazing material bonding.

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