KR101758379B1

KR101758379B1 - Method for producing substrate for power module, substrate for power module, substrate for power module with heat sink, and power module

Info

Publication number: KR101758379B1
Application number: KR1020110010197A
Authority: KR
Inventors: 히로시 도노무라; 요시유키 나가토모; 요시로우 구로미츠
Original assignee: 미쓰비시 마테리알 가부시키가이샤
Priority date: 2011-02-01
Filing date: 2011-02-01
Publication date: 2017-07-14
Also published as: KR20120089069A

Abstract

Disclosed is a method for manufacturing a substrate for a power module, which can obtain a substrate for a power module with high reliability in cooling cycle and reliability, in which a metal plate and a ceramics substrate are reliably and easily bonded at low cost.
(S1) an Si bonding step (S1) of bonding Si to at least one of a bonding surface of a ceramic substrate and a bonding surface of a metal sheet to form a Si layer containing 0.002 mg / cm2 or more and 1.2 mg / (S2) for laminating a ceramic substrate and a metal plate via a Si layer, a heating step (S3) for forming a molten metal region at an interface between the ceramics substrate and the metal plate, and solidifying the molten metal region, And a solidifying step (S4) for joining the Si layer and the metal plate to each other to diffuse Si of the Si layer toward the metal plate in the heating step (S3), thereby forming a molten metal region at the interface between the ceramic substrate and the metal plate.

Description

TECHNICAL FIELD [0001] The present invention relates to a substrate for a power module, a substrate for a power module, a substrate for a power module with a heat sink, and a power module. BACKGROUND OF THE INVENTION 1. Field of the Invention }

The present invention relates to a method for manufacturing a substrate for a power module used in a semiconductor device for controlling a large current and a high voltage, a substrate for a power module manufactured by the method for manufacturing a substrate for the power module, To a power module having a substrate for a power module.

Among the semiconductor devices, the power module for power supply has a relatively high heating value. Therefore, as a substrate on which the power module is mounted, for example, as shown in Patent Document 1, on a ceramic substrate made of AlN (aluminum nitride) And a substrate for a power module joined with the solder material is used.

The metal plate is formed as a circuit layer, and a semiconductor chip of a power element is mounted on the metal plate with a solder material interposed therebetween.

It has also been proposed that a metal plate such as Al is joined to a lower surface of a ceramic substrate to dissipate heat to form a metal layer, and the entire power module substrate is bonded onto the heat dissipating plate through the metal layer.

As a means for forming a circuit layer, there is a method in which a circuit pattern is formed on a metal plate after the metal plate is bonded to a ceramic substrate. In addition, for example, as disclosed in Patent Document 2, A method of joining to a ceramic substrate has been proposed.

(Patent Document 1) Japanese Laid-Open Patent Publication No. 2003-086744

(Patent Document 2) Japanese Laid-Open Patent Publication No. 2008-311294

However, when brazing the ceramics substrate and the metal plate, a brazing filler metal of an Al-Si-based alloy containing Si in an amount of 7.5% by mass or more is often used in order to set a low melting point. As described above, an Al-Si based alloy containing a relatively large amount of Si is insufficient in ductility, making it difficult to produce a laminated sheet by rolling or the like.

In addition, in the case of using solder tin, the oxide film was present on three surfaces of the metal plate surface and both surfaces of the solder tin, and the total thickness of the oxide film existing in the interface portion between the metal plate and the ceramic substrate tended to become thick.

In addition, a brazing material is placed between the ceramics substrate and the metal plate and heated by pressing them in the lamination direction. It is necessary to laminate the brazing material, the ceramics substrate and the metal plate so that the position of the brazing material is not shifted when the pressing is performed .

Particularly, as described in Patent Document 2, in the case of joining metal pieces formed in a circuit pattern shape in advance via solder paste, since the shape of the joint surface is complicated, the positional accuracy of the solder paste, ceramic substrate, There was a need to improve.

Further, when the position of the solder paste is shifted, a molten metal layer can not be sufficiently formed between the ceramic substrate and the metal plate, and there is a possibility that the bonding strength between the ceramic substrate and the metal plate is lowered.

In recent years, the miniaturization and thinning of the power module have progressed, and the use environment has become stricter. As a result, the amount of heat generated from electronic components such as mounted semiconductor devices tends to increase. As described above, As shown in Fig. In this case, since the substrate for the power module is restrained by the heat sink, a large shearing force acts on the bonding interface between the metal plate and the ceramics substrate at the time of a cooling / heating cycle load, and therefore the bonding strength between the ceramics substrate and the metal plate Improvement is required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances and provides a method of manufacturing a substrate for a power module, which can obtain a substrate for a power module with high reliability of a cooling cycle and a reliability in which a metal plate and a ceramics substrate are reliably joined at low cost easily, An object of the present invention is to provide a power module substrate manufactured by the method for manufacturing a substrate for a power module, a substrate for a power module with a heat sink, and a power module including the substrate for the power module.

In order to achieve the above object, a manufacturing method of a substrate for a power module according to the present invention is a manufacturing method of a substrate for a power module in which a metal plate made of aluminum is laminated and bonded on the surface of a ceramics substrate, An Si bonding step of bonding Si to at least one of a bonding surface of the substrate and a bonding surface of the metal sheet to form a Si layer containing 0.002 mg / cm 2 to 1.2 mg / cm 2 of Si; A heating step of pressing and heating the laminated ceramic substrate and the metal plate in a lamination direction to form a molten metal region at an interface between the ceramics substrate and the metal plate, And a solidifying step of bonding the ceramic substrate and the metal plate by solidifying the molten metal region, In the thermal process it is characterized by forming the interface between the molten metal zone formed of Al-Si process to step on the ceramic substrate and the metal plate by spreading the Si in the Si layer toward the metal plate.

In the method for manufacturing a substrate for a power module having this structure, Si is fixed to at least one of a bonding surface of the ceramics substrate and a bonding surface of the metal plate to form a Si layer containing 0.002 mg / cm 2 to 1.2 mg / And the molten metal region comprising the Al-Si process system is formed at the interface between the ceramics substrate and the metal plate by diffusing Si of the Si layer toward the metal plate in the heating step It is not necessary to use an Al-Si-based solder paste which is difficult to manufacture, and a substrate for a power module in which a metal plate and a ceramics substrate are reliably bonded at a low cost can be manufactured.

Further, since the Si layer is directly formed on at least one of the bonding surface of the ceramics substrate and the bonding surface of the metal plate without using the brazing material, it is not necessary to perform the positioning work of the brazing filler metal. Thus, for example, even when a metal piece previously formed in a circuit pattern shape is bonded to a ceramic substrate, troubles due to positional deviation can be prevented in advance.

In addition, when the Si layer is formed directly on the metal plate and the ceramic substrate, the oxide film is formed only on the surface of the metal plate, so that the total thickness of the oxide film existing at the interface between the metal plate and the ceramic substrate becomes thinner, .

In addition, a Si layer is formed on at least one of the bonding surface of the ceramics substrate and the bonding surface of the metal plate. However, from the viewpoint of productivity, it is preferable to form the Si layer on the bonding surface of the metal plate. When forming the Si layer on the bonding surface of the ceramic substrate, the Si layer must be formed on each ceramic substrate. On the other hand, when the Si layer is formed on the bonding surface of the metal plate, the Si layer can be continuously formed from one end to the other end with respect to a long metal roll wound in a roll shape,

In addition, since the amount of Si to be bonded is 0.002 mg / cm 2 or more, a molten metal region formed by the Al-Si process system can be reliably formed at the interface between the ceramic substrate and the metal plate, .

Further, since the amount of Si to be fixed is 1.2 mg / cm < 2 > or less, it is possible to prevent cracks from occurring in the Si layer itself and to securely form a molten metal region made of an Al-Si process system at the interface between the ceramic substrate and the metal plate can do. In addition, it is possible to prevent the strength of the metal plate in the vicinity of the interface from excessively increasing due to diffusion of Si excessively toward the metal plate side. Therefore, thermal stress can be absorbed by the metal plate when a cooling / heating cycle is loaded on the substrate for a power module, and cracking of the ceramic substrate can be prevented.

Here, in the Si fixing step, it is preferable that Al is fixed together with Si.

In this case, since Al is fixed together with Si, the Si layer to be formed contains Al and Si, so that generation of cracks in the Si layer can be suppressed. Further, the Si layer is preferentially melted, and the molten metal region can be surely formed, so that the ceramics substrate and the metal plate can be firmly bonded. In order to fix Al together with Si, Si and Al may be deposited at the same time, or may be sputtered using an alloy of Si and Al as a target. Further, Si and Al may be laminated.

Preferably, Si is fixed to at least one of the bonding surface of the ceramics substrate and the bonding surface of the metal plate by vapor deposition, CVD or sputtering.

In this case, Si is surely adhered to at least one of the bonding surface of the ceramics substrate and the bonding surface of the metal plate by vapor deposition, CVD or sputtering, so that the Si layer can be reliably formed at the bonding interface between the ceramic substrate and the metal plate . In addition, it is possible to adjust the bonding amount of Si with good precision, to securely form the molten metal region, and firmly bond the ceramics substrate and the metal plate.

Further, the substrate for a power module of the present invention is a substrate for a power module produced by the above-described method for manufacturing a substrate for a power module, wherein Si is solid-dissolved in the metal plate, And the Si concentration in the vicinity of the interface is set within a range of 0.05 mass% or more and 0.5 mass% or less.

In the substrate for power module having this structure, since Si is solid in the metal plate and the Si concentration at the bonding interface side portion is set to 0.05 mass% or more, Si is sufficiently diffused toward the metal plate in the heating step described above, And the ceramic plate are firmly bonded to each other. Further, the bonded interface side portion of the metal plate is solidified by Si. As a result, it is possible to prevent the occurrence of cracks in the metal plate portion and to improve the bonding reliability of the substrate for the power module.

In addition, since the Si concentration in the bonding interface side portion is set to 0.5 mass% or less, it is possible to prevent the strength of the metal plate in the vicinity of the interface from excessively increasing, and when the cooling module is loaded on the substrate for power module, It is possible to prevent the ceramic substrate from cracking or the like.

The substrate for a power module of the present invention is a substrate for a power module produced by a method for manufacturing a substrate for a power module, wherein the ceramic substrate is made of AlN, Al ₂ O _3, or Si ₃ N ₄ .

In the substrate for a power module having this structure, since the ceramics substrate is composed of any of AlN, Al ₂ O ₃ and Si ₃ N ₄ excellent in insulation property and strength, it is possible to provide a high-quality substrate for a power module.

The board for a power module to which the heat sink of the present invention is attached is characterized by including the board for the power module and the heat sink for cooling the board for the power module.

According to the substrate for a power module having the heat sink of this configuration, since the heat sink for cooling the substrate for the power module is provided, the heat generated in the substrate for the power module can be efficiently cooled by the heat sink.

The power module of the present invention is characterized by including the substrate for the power module and the electronic component mounted on the power module substrate.

According to the power module of this configuration, even when the bonding strength between the ceramic substrate and the metal plate is high and the use environment is strict, the reliability can be dramatically improved.

According to the present invention, there is provided a method of manufacturing a substrate for a power module, which can obtain a substrate for a power module with high reliability of a cooling cycle and reliability, in which a metal plate and a ceramics substrate are reliably and easily bonded at low cost, It is possible to provide a power module including a substrate for a power module manufactured by the above method, a substrate for a power module with a heat sink, and a substrate for the power module.

1 is a schematic explanatory diagram of a power module using a substrate for a power module which is an embodiment of the present invention.
Fig. 2 is an explanatory view showing a Si concentration distribution of a circuit layer and a metal layer of a substrate for power module which is an embodiment of the present invention. Fig.
3 is a flowchart showing a method of manufacturing a substrate for a power module which is an embodiment of the present invention.
4 is an explanatory view showing a manufacturing method of a substrate for a power module which is an embodiment of the present invention.
Fig. 5 is an explanatory diagram showing the vicinity of the bonded interface between the metal plate and the ceramics substrate in Fig. 4;

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Fig. 1 shows a substrate for a power module, a substrate for a power module with a heat sink, and a power module according to an embodiment of the present invention.

The power module 1 includes a power module substrate 10 on which a circuit layer 12 is formed, a semiconductor chip 3 bonded to the surface of the circuit layer 12 via a solder layer 2, And a sink 4 are provided. Here, the solder layer 2 is, for example, a Sn-Ag based, Sn-In based, or Sn-Ag-Cu based solder material. In the present embodiment, a Ni plating layer (not shown) is formed between the circuit layer 12 and the solder layer 2.

The substrate 10 for a power module includes a ceramic substrate 11, a circuit layer 12 formed on one surface (upper surface in Fig. 1) of the ceramic substrate 11, And a metal layer 13 disposed on the surface (lower surface in Fig. 1).

The ceramic substrate 11 prevents electric connection between the circuit layer 12 and the metal layer 13, and is made of AlN (aluminum nitride) having high insulating properties. The thickness of the ceramic substrate 11 is set within a range of 0.2 to 1.5 mm, and is set to 0.635 mm in the present embodiment. 1, the width of the ceramic substrate 11 is set wider than the width of the circuit layer 12 and the metal layer 13. In this embodiment,

The circuit layer 12 is formed by bonding a metal plate 22 having conductivity to one surface of a ceramic substrate 11. In this embodiment, the circuit layer 12 is formed by bonding a metal plate 22 made of aluminum (so-called 4N aluminum) having a purity of 99.99% or more to a ceramic substrate 11.

The metal layer 13 is formed by bonding a metal plate 23 to the other surface of the ceramic substrate 11. In the present embodiment, the metal layer 13 is formed by bonding a metal plate 23 made of a rolled plate of aluminum (so-called 4N aluminum) having a purity of 99.99% or more to the ceramics substrate 11 in the same manner as the circuit layer 12 .

The heat sink 4 is for cooling the substrate 10 for a power module described above and includes a top plate 5 bonded to the substrate 10 for power module and a top plate 5 And a flow path 6 are provided. The heat sink 4 (top plate portion 5) is preferably made of a material having good thermal conductivity, and in the present embodiment, it is made of A6063 (aluminum alloy).

In this embodiment, a buffer layer 15 made of a composite material (for example, AlSiC or the like) containing aluminum, aluminum alloy or aluminum is formed between the top plate 5 of the heat sink 4 and the metal layer 13 .

2, at the central portion in the width direction of the bonding interface 30 between the ceramic substrate 11, the circuit layer 12 (the metal plate 22) and the metal layer 13 (the metal plate 23) Si is solidified in the layer 12 (the metal plate 22) and the metal layer 13 (the metal plate 23), and the Si concentration gradually decreases as the Si layer is separated from the bonding interface 30 in the stacking direction (Not shown). Here, the concentration of Si on the bonding interface 30 side of the concentration gradient layer 33 is set within the range of 0.05 mass% or more and 0.5 mass% or less.

The Si concentration on the bonding interface 30 side of the concentration gradient layer 33 is an average value measured five points at a position of 50 占 퐉 from the bonding interface 30 by EPMA analysis (spot diameter 30 占 퐉). 2 is a graph showing the results of line analysis in the lamination direction at the center portions of the circuit layer 12 (metal plate 22) and the metal layer 13 (metal plate 23) Concentration.

Hereinafter, a method of manufacturing the power module substrate 10 having the above-described structure will be described with reference to Figs. 3 to 5. Fig.

(Si bonding step (S1))

First, as shown in Figs. 4 and 5, Si is adhered to the bonding surfaces of the metal plates 22 and 23 by sputtering to form Si layers 24 and 25, respectively. Here, the amount of Si fixation in the Si layers 24, 25 is adjusted to 0.002 mg / cm2 or more and 1.2 mg / cm2 or less. In the present embodiment, the amount of Si fixation in the Si layers 24 and 25 is set to 0.466 mg / cm 2.

(Laminating step (S2))

Next, as shown in Fig. 4, the metal plate 22 is laminated on one surface side of the ceramic substrate 11, and the metal plate 23 is laminated on the other surface side of the ceramics substrate 11. At this time, as shown in Fig. 4 and Fig. 5, the metal plates 22 and 23 are laminated so that the surfaces on which the Si layers 24 and 25 are formed face the ceramics substrate 11. That is, the Si layers 24 and 25 are interposed between the metal plates 22 and 23 and the ceramics substrate 11, respectively. Thus, the layered product 20 is formed.

(Heating step (S3))

Next, the stacked body 20 formed in the stacking step S2 is charged into the vacuum heating furnace under the pressure (pressure 1 to 35 kgf / cm2) in the stacking direction and heated. As shown in Fig. 5, Molten metal regions 26 and 27 are formed at the interface between the metal plates 22 and 23 and the ceramic substrate 11, respectively. As shown in Fig. 5, the Si layers 24 and 25 of the molten metal regions 26 and 27 are diffused toward the metal plates 22 and 23, whereby the Si layers 24 and 25 of the metal plates 22 and 23, 25) is increased and the melting point is lowered. In addition, when the pressure is less than 1 kgf / cm 2, there is a possibility that the ceramic substrate 11 and the metal plates 22 and 23 can not be satisfactorily bonded. In addition, when the above-described pressure exceeds 35 kgf / cm 2, the metal plates 22 and 23 may be deformed. Therefore, it is preferable that the pressure when the laminate 20 is pressed is in the range of 1 to 35 kgf / cm < 2 >.

Here, in the present embodiment, the pressure in the vacuum furnace is set to 10 ^-6 to 10 ^-3 Pa and the heating temperature is set in the range of 630 ° C to 655 ° C.

(Solidification step (S4))

Next, the temperature is kept constant while the molten metal regions 26 and 27 are formed. Then, the Si in the molten metal regions 26 and 27 is further diffused toward the metal plates 22 and 23. As a result, the Si concentration in the portion where the molten metal regions 26 and 27 are gradually lowered and the melting point is increased, so that the solidification progresses while maintaining the temperature constant. In other words, the ceramics substrate 11 and the metal plates 22 and 23 are bonded by so-called Transient Liquid Phase Diffusion Bonding. After the solidification proceeds in this way, cooling is carried out to room temperature.

In this manner, the circuit board 12 and the metal plates 22 and 23 to be the metal layer 13 and the ceramics substrate 11 are joined together to produce the power module substrate 10 of the present embodiment.

The ceramic substrate 11, the circuit layer 12 (the metal plate 22), and the metal layer 13 (the metal plate (not shown)) are formed in the power module substrate 10 and the power module 1, 23) form molten metal regions 26, 27 by diffusing Si of the Si layers 24, 25 formed on the bonding surfaces of the metal plates 22, 23 toward the metal plates 22, 23, The Si of the regions 26 and 27 is diffused by the metal plates 22 and 23 and solidified to bond the ceramics substrate 11 and the circuit layer 12 (metal plate 22) and the metal layer 13 (metal plate 23) can be bonded.

At the central portion in the width direction of the bonding interface 30 between the ceramic substrate 11 and the circuit layer 12 (metal plate 22) and the metal layer 13 (metal plate 23), the circuit layer 12 The concentration gradient layer 33 is formed in which Si is dissolved in the metal layer 13 (metal plate 23) and the metal layer 13 (metal plate 23) and the concentration of Si gradually decreases from the bonding interface 30 in the stacking direction And the concentration of Si on the bonding interface 30 side of the concentration gradient layer 33 is set within a range of 0.05 mass% or more and 0.5 mass% or less. Therefore, the circuit layer 12 (the metal plate 22) (Metal plate 23) on the bonding interface 30 side is strengthened to prevent breakage of the circuit layer 12 (metal plate 22) and the metal layer 13 (metal plate 23) .

Further, in the heating step (S3), Si is sufficiently diffused toward the metal plates (22, 23), and the metal plates (22, 23) and the ceramic span (11) are firmly bonded.

The Si fixing step (S1) of securing Si to the bonding surface of the metal sheet to form Si layers (24, 25) containing Si at not less than 0.002 mg / cm2 and not more than 1.2 mg / Si molten metal regions 26, 27 (Al-Si process system) are formed on the interface between the ceramic substrate 11 and the metal plates 22, 23 by diffusing Si of the Si layers 24, 25 toward the metal plates 22, It is not necessary to use an Al-Si type solder paste which is difficult to manufacture and the substrate 10 for a power module in which the metal plates 22 and 23 and the ceramics substrate 11 are reliably bonded at a low cost ) Can be produced.

The molten metal regions 26, 26 made of an Al-Si process system are formed on the interface between the ceramics substrate 11 and the metal plates 22, 23 because the amount of Si fixation in the Si layers 24, 25 is 0.002 mg / 27 can be surely formed, and the metal plates 22, 23 and the ceramics substrate 11 can be firmly bonded.

In addition, since the Si fixing amount in the Si layers 24 and 25 is 1.2 mg / cm 2 or less, cracks can be prevented from occurring in the Si layers 24 and 25 themselves.

Further, since the Si layers 24 and 25 are formed directly on the bonding surfaces of the metal plates 22 and 23 without using solder paste, it is not necessary to carry out the positioning work of the solder paste. Therefore, the substrate 10 for power module can be manufactured efficiently.

Since the Si layers 24 and 25 are formed, the oxide film interposed between the metal plates 22 and 23 and the ceramic substrate 11 is present only on the surfaces of the metal plates 22 and 23. Therefore, Can be improved.

In this embodiment, since the Si layers 24 and 25 are formed on the bonding surfaces of the metal plates 22 and 23, the Si bonding step S1 can be performed efficiently.

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

For example, the description has been made on the assumption that the metal plate constituting the circuit layer and the metal layer is a pure aluminum rolled plate having a purity of 99.99%. However, the present invention is not limited to this, and aluminum (2N aluminum) having a purity of 99% may be used.

Further, the buffer layer made of a composite material containing aluminum, aluminum alloy or aluminum (for example, AlSiC or the like) is formed between the top plate portion of the heat sink and the metal layer, but this buffer layer may be omitted.

Although the heat sink is described as being made of aluminum, it may be made of an aluminum alloy, a composite material containing aluminum, or the like. Further, although the heat sink is described as having a channel for the cooling medium, the structure of the heat sink is not particularly limited, and various types of heat sinks can be used.

In addition, the ceramic substrate is made of AlN, but the present invention is not limited to this, and it may be made of other ceramics such as Si ₃ N ₄ and Al ₂ O ₃ .

In addition, although the description has been made on the assumption that the Si fixing process is performed such that Si is fixed to the bonding surface of the metal plate, the present invention is not limited thereto. Si may be adhered to the bonding surface of the ceramic substrate.

Further, in the above description, the Si layer is formed by the sputtering in the Si bonding process, but the present invention is not limited thereto, and the Si layer may be formed by fixing Si by vapor deposition or CVD. In the Si bonding process, for example, Si and Al may be deposited at the same time, or a Si layer containing Al and Si may be formed by sputtering using an alloy of Si and Al as a target. Alternatively, Al and Si may be laminated.

In the above description, the ceramics substrate and the metal plate are bonded using a vacuum heating furnace. However, the present invention is not limited to this, and the ceramics substrate and the metal plate may be joined in an N ₂ atmosphere, an Ar atmosphere or a He atmosphere .

Example

A confirmation experiment conducted to confirm the effectiveness of the present invention will be described.

Two sheets of metal plates made of 4N aluminum having a thickness of 0.6 mm were prepared, and Si was fixed to one surface of these metal plates by vacuum deposition. The two sheets of metal plates were placed on both surfaces of a ceramic substrate made of AlN having a width of 40 mm and a thickness of 0.635 mm (Vacuum degree: 10 ^-3 to 10 ^-5 Pa) at a temperature of 630 to 650 ° C under a pressure of 1 to 5 kgf / cm 2 in the stacking direction , A substrate for a power module having a ceramic substrate, a circuit layer and a metal layer was produced.

Here, the thickness (Si fixing amount) of the Si layer formed by vacuum evaporation was 0.008 탆 (0.0019 ㎎ / cm 2), 0.6 탆 (0.1398 ㎎ / cm 2), 0.8 탆 (0.1864 ㎎ / Cm2), 1.2 占 퐉 (0.2796 mg / cm2), 1.5 占 퐉 (0.3495 mg / cm2), 2.4 占 퐉 (0.5592 mg / cm2), 3.6 占 퐉 (0.8388 mg / cm2), 4.8 占 퐉 (1.1184 mg / Mu] m (1.3980 mg / cm < 2 >).

An aluminum plate A6063 of 50 mm x 60 mm and a thickness of 5 mm corresponding to the top plate of the heat sink was bonded to the metal layer side of the substrate for power module thus formed with a buffer layer of 0.9 mm in thickness made of 4N aluminum interposed therebetween .

These test specimens were subjected to a cooling cycle of -45 ° C to 105 ° C to compare their bonding ratios. The evaluation results are shown in Table 1.

The bonding ratio was calculated by the following formula. Here, the initial bonding area is an area to be bonded before bonding.

Bonding ratio = (initial bonding area - peeling area) / initial bonding area

In Comparative Example 1 in which the thickness of the Si layer was 0.008 占 퐉 (0.0019 mg / cm2) and the thickness of the Si layer was 6.0 占 퐉 (1.3980 mg / cm2) Or less, and it was confirmed that the bonding strength between the ceramic substrate and the metal plate was insufficient.

On the other hand, in Examples 1 to 8 in which the thickness of the Si layer was set in the range of 0.6 to 4.8 占 퐉 (0.1398 to 1.1184 mg / cm2), the bonding ratio in 1000 cycles of the thermal and thermal cycles was 95% 70% or more, and it was confirmed that the ceramics substrate and the metal plate were firmly bonded.

Particularly, in Examples 3 to 6, in which the thickness of the Si layer was in the range of 1.0 to 2.4 占 퐉 (0.2330 to 0.5592 mg / cm2), the bonding ratio at 1000 times in the cooling / heating cycle was 99.5% 85% or more, and it was confirmed that the bonding strength between the ceramic substrate and the metal plate was further improved.

Next, two metal plates made of 4N aluminum having a thickness of 0.6 mm were prepared, and Si was fixed to one surface of these metal plates by vacuum evaporation. These two metal plates were made of ceramics made of AlN having a width of 40 mm and a thickness of 0.635 mm (Vacuum degree: 10 ^-3 to 10 ^-5 Pa) at a pressure of 5 to 35 kgf / cm 2 in a lamination direction, and the laminate was laminated at 630 to 650 C to prepare a substrate for a power module having a ceramic substrate, a circuit layer and a metal layer.

Here, the thickness (Si fixing amount) of the Si layer formed by vacuum evaporation was 0.008 탆 (0.0019 ㎎ / cm 2), 0.1 탆 (0.0233 ㎎ / cm 2), 0.4 탆 (0.0932 ㎎ / Cm2), 1.5 占 퐉 (0.3495 mg / cm2), 2.4 占 퐉 (0.5592 mg / cm2) and 3.6 占 퐉 (0.1864 mg / cm2) A substrate for a power module was fabricated in which 12 levels were formed, each having a thickness of 1 占 퐉 (0.8388 mg / cm2), 4.8 占 퐉 (1.1184 mg / cm2) and 6.0 占 퐉 (1.3980 mg /

These test specimens were subjected to a cooling cycle of -45 ° C to 105 ° C to compare their bonding ratios. The evaluation results are shown in Table 2.

The bonding rate was calculated by the following formula. Here, the initial bonding area is an area to be bonded before bonding.

Bonding ratio = (initial bonding area - peeling area) / initial bonding area

With respect to these test pieces, the Si concentration in the vicinity of the joint interface (50 mu m from the joint interface) of the ceramic substrate in the metal plate was measured by EPMA analysis (spot diameter 30 mu m). The measurement results are shown together in Table 2.

In Comparative Example 3 in which the thickness of the Si layer was 0.008 占 퐉 (0.0019 mg / cm2), even when the pressing pressure at the time of bonding was increased to 5 to 35 kgf / cm2, the bonding ratio at the time of 1000 heat / And it was confirmed that the bonding strength between the ceramic substrate and the metal plate was insufficient. Further, in Comparative Example 4 in which the Si layer had a thickness of 6.0 占 퐉 (1.3980 mg / cm2), it was confirmed that the bonding ratio at 4,000 times of the cooling / heating cycle was lowered to 60.3%.

On the other hand, in Examples 9 to 18 in which the thickness of the Si layer was in the range of 0.1 to 4.8 占 퐉 (0.0233 to 1.1184 mg / cm2), the bonding ratio in the 1000 cycles of the heat and cooling cycles was 89% 70% or more, and it was confirmed that the ceramics substrate and the metal plate were firmly bonded.

When the thickness of the Si layer is 0.1 to 4.8 탆 (0.0233 to 1.1184 mg / cm 2), the Si concentration in the vicinity of the bonding interface of the ceramic substrate (50 탆 from the bonding interface) is 0.1% It was confirmed that the value became within the following range.

1: Power module
3: Semiconductor chip (electronic parts)
10: PCB for power module
11: ceramic substrate
12: Circuit layer
13: metal layer
22, 23: metal plate
24, 25: Si layer
26, 27: molten metal region
30: bonding interface

Claims

A manufacturing method of a substrate for a power module in which a metal plate made of aluminum is laminated and bonded to the surface of a ceramics substrate,
An Si bonding step of bonding Si to at least one of a bonding surface of the ceramics substrate and a bonding surface of the metal sheet to form a Si layer containing 0.002 mg / cm 2 to 1.2 mg / cm 2 of Si;
A lamination step of laminating the ceramics substrate and the metal plate via the Si layer,
A heating step of pressing and heating the laminated ceramic substrate and the metal plate in a lamination direction to form a molten metal region at an interface between the ceramics substrate and the metal plate,
And a solidifying step of solidifying the molten metal region to bond the ceramic substrate and the metal plate,
Wherein the molten metal region comprising the Al-Si process system is formed at the interface between the ceramic substrate and the metal plate by diffusing Si of the Si layer toward the metal plate in the heating step.

The method according to claim 1,
Wherein the Si bonding step comprises bonding Al together with Si.

The method according to claim 1,
The Si fixing step may be performed by fixing Si to at least one of a bonding surface of the ceramics substrate and a bonding surface of the metal plate by applying plating, vapor deposition, CVD, sputtering, cold spray, or paste or ink in which the powder is dispersed Wherein the step of forming the substrate comprises the steps of:

A power module substrate produced by the method for manufacturing a substrate for a power module according to any one of claims 1 to 3,
Wherein Si is solid-dissolved in the metal plate, and a Si concentration of 50 탆 is set within a range of 0.05 mass% or more and 0.5 mass% or less from a bonding interface of the metal plate with the ceramics substrate.

5. The method of claim 4,
Wherein the ceramic substrate is made of any of AlN, Al ₂ O ₃ and Si ₃ N ₄ .

A substrate for a power module, comprising: the substrate for a power module according to claim 4; and a heat sink for cooling the substrate for the power module.

A power module comprising: the substrate for a power module according to claim 4; and an electronic component mounted on the substrate for the power module.