JP5884291B2 - Power module board unit with heat sink - Google Patents

Description

The present invention relates to a high current, the heat sink with the power module board units constituting the power module for controlling the high voltage.

  2. Description of the Related Art Conventionally, as a semiconductor device that controls a large current and a high voltage, a power module having a configuration in which an electronic component such as a semiconductor chip is mounted on a power module substrate is known. The power module substrate is formed by laminating a metal layer for a circuit layer on which electronic components are mounted on one surface of a ceramic substrate and a metal layer for a heat dissipation layer on the other surface. A heat sink that releases heat generated from the electronic component is attached to the heat dissipation layer by brazing or soldering.

  In the power module described in Patent Document 1, a recess is provided in the heat sink to be joined to the power module substrate, and a structure in which the power module substrate having the heat radiation layer is fitted into the recess of the heat sink is employed. The heat sink positioning and bonding strength are improved.

  In the power module described in Patent Document 2, a concavo-convex shape that engages with the heat dissipation layer and the heat sink of the power module substrate is provided on the joint surface to improve the positioning accuracy between the power module substrate and the heat sink.

JP 2010-62203 A JP 2009-188327 A

  However, in the structure in which the power module substrate is fitted into the recess of the heat sink as described in Patent Document 1, an oxide film on the surface of the brazing material remains between the heat sink and the power module substrate during brazing. May not be discharged, resulting in poor bonding. In addition, in the case of a structure that engages the concavo-convex shape provided on the joint surface as described in Patent Document 2, the distance between the substrate and the heat sink is not stable, and the brazing foil is partially insufficient during brazing. There is a possibility that bonding failure may occur due to protrusion.

  Moreover, when the recessed part which inserts the board | substrate for power modules in a heat sink as described in patent document 1 is formed, the clad | crud material by which the brazing material was laminated | stacked on the surface of the aluminum material cannot be used, and joining work It is difficult to improve the performance.

  The present invention has been made in view of such circumstances, and provides a power module substrate with a heat sink that can improve positioning and bonding properties and is excellent in workability when bonding a power module substrate and a heat sink. The purpose is to do.

  The present invention provides a power module substrate in which a metal plate-like heat dissipation layer in which a plurality of recesses having outer edges protruding from the surface are formed and a ceramic substrate are bonded, and a height higher than the depth of the recesses. A heat sink comprising a metal plate-like top plate having a plurality of protrusions that engage with the recesses at a low level, and the power module substrate and the heat sink are engaged with the recesses and the protrusions. A power module substrate unit with a heat sink, which is laminated in a state where a gap is left between the heat dissipation layer and the top plate by bringing an outer edge portion into contact with the surface of the top plate.

  According to this power module substrate unit with a heat sink, the power module substrate and the top plate are laminated in a state where the concave portion of the heat dissipation layer and the convex portion of the heat sink are engaged with each other. The module substrate and the heat sink can be bonded at a desired relative position. Moreover, since the relative position between the power module substrate and the heat sink is stabilized even in the joining operation between the heat dissipation layer and the top plate due to the engagement of the uneven shape, the joining workability is also good. In addition, a hole, a groove | channel, etc. are employable as a shape of a recessed part.

  Furthermore, a gap is formed between the heat dissipation layer and the top plate according to the height of the outer edge by the outer edge protruding from the surface of the heat dissipation layer contacting the top plate. A joining material such as a brazing material is supplied uniformly, enabling reliable joining.

  In this power module substrate unit with a heat sink, it is preferable that the height of the outer edge portion of the recess is not less than 50 μm and not more than 150 μm from the surface of the heat dissipation layer. By setting the height of the outer edge portion in this manner, the size of the gap between the heat radiation layer and the top plate becomes appropriate, so that the power module substrate and the heat sink are stably bonded.

  In the power module substrate unit with a heat sink, it is preferable that a bonding material is interposed between the heat dissipation layer of the power module substrate and the top plate of the heat sink. For example, when this bonding material is a brazing foil, it can be heated in a state of being maintained in a predetermined positional relationship by the concavo-convex shape, so that the heat radiation layer and the top plate can be brazed at an accurate position. .

  Furthermore, in this power module substrate unit with a heat sink, the thickness of the bonding material is preferably 100 μm or more and 200 μm or less. In this case, it is possible to obtain a power module substrate with a heat sink in which the heat dissipation layer and the top plate are reliably bonded with a sufficient bonding material.

  Further, in this power module substrate unit with a heat sink, the convex portion of the top plate has a substantially hemispherical concave portion formed on the top plate in a shape corresponding to the concave portion of the heat dissipation layer, and the top plate Provided by a ball arranged to engage with the recess, or the protrusion of the top plate is a substantially band-like recess formed in the top plate in a shape corresponding to the recess of the heat dissipation layer And a wire disposed so as to engage with the concave portion of the top plate. In these cases, instead of forming a convex shape on the top plate, the convex portion can be easily formed by forming a concave portion and arranging a ball or a wire.

  The present invention also provides a power module substrate in which a metal plate-like heat dissipation layer in which a plurality of recesses having outer edges protruding from the surface are formed and a ceramic substrate are bonded, and a height higher than the depth of the recesses. A heat sink comprising a metal plate-like top plate having a plurality of projections that are low and engage with the recesses, and a bonding layer provided between the heat radiation layer of the power module substrate and the top plate of the heat sink The power module substrate and the heat sink are engaged with the concave portion and the convex portion, and the outer edge portion is in contact with the surface of the top plate. It is a power module substrate with a heat sink in which the heat dissipation layer and the top plate of the heat sink are joined.

  In this case, since a predetermined gap is formed between the heat dissipation layer and the top plate according to the height of the outer edge, a power module substrate with a heat sink in which the heat dissipation layer and the top plate are joined without inclination is obtained. be able to.

  According to the present invention, since the relative position of the heat dissipation layer and the top plate is stabilized by the engagement of the concavo-convex shape, for example, when the power module substrate and the heat sink are temporarily joined and moved, the displacement is prevented. A unit with good workability and positioning is realized. In addition, since a uniform gap is formed between the heat dissipation layer and the top plate, it is possible to prevent the bonding material such as the brazing material from being partially insufficient or protruding, and the heat sink is bonded reliably and accurately. A power module substrate with a heat sink can be realized. Further, in the case of brazing or soldering using a flux such as Nocolok brazing, the flux is quickly discharged from the gap at the time of joining, and joining defects such as voids can be prevented.

It is principal part sectional drawing which shows one Embodiment of the board | substrate unit for power modules with a heat sink which concerns on this invention. It is sectional drawing which shows the manufacturing method of the thermal radiation layer which comprises the board | substrate unit for power modules with a heat sink shown in FIG. It is principal part sectional drawing which shows the joining material of the heat sink and the board | substrate for power modules in the board unit for power modules with a heat sink shown in FIG. It is sectional drawing which shows the board | substrate for power modules with a heat sink which concerns on this invention. It is sectional drawing which shows the other example of the engagement structure of a heat sink and a thermal radiation layer. It is sectional drawing which shows another example of the engagement structure of a heat sink and a thermal radiation layer. It is sectional drawing which shows the structural example of the joining material of the heat sink and heat dissipation layer in this invention.

Hereinafter, embodiments of a power module substrate unit with a heat sink and a power module substrate with a heat sink according to the present invention will be described.
As shown in FIG. 1, the power module substrate unit 10 with a heat sink includes a power module substrate 20 in which a metal plate-like heat radiation layer 21 and a ceramic substrate 22 are joined, and a metal plate-like top plate 31. A heat sink 30 provided is laminated with a gap 11 between the heat dissipation layer 21 and the top plate 31.

More specifically, the power module substrate 20 has a metal plate-like heat radiation layer 21 and a circuit layer 23 bonded to both surfaces of a ceramic substrate 22. An electronic component (not shown) is bonded to the surface of the circuit layer 23. The ceramic substrate 22 is made of, for example, nitride ceramics such as AlN (aluminum nitride), Si ₃ N ₄ (silicon nitride), or oxide ceramics such as Al ₂ O ₃ (alumina).

  As the metal plates constituting the heat radiation layer 21 and the circuit layer 23, aluminum having a purity of 99.90% by mass or more is used. According to JIS standards, 1N90 (purity 99.90% by mass or more: so-called 3N aluminum) or 1N99 (Purity 99.99 mass% or more: so-called 4N aluminum) can be used. In the power module substrate 20, the ceramic substrate 22, the heat dissipation layer 21, and the circuit layer 23 are made of brazing material such as Al—Si, Al—Ge, Al—Cu, Al—Mg, or Al—Mn. Joined by brazing or diffusion bonding.

  In the case of brazing, the heat-dissipating layer 21 and the circuit layer 23 are laminated on both surfaces of the ceramic substrate 22 via a brazing material foil, and this laminate is pressurized in the laminating direction in an inert gas atmosphere, a reducing gas atmosphere or a vacuum atmosphere. The heat dissipation layer 21 and the circuit layer 23 are each bonded to the ceramic substrate 22 by heating in the state and melting the brazing material foil.

  In the case of diffusion bonding (Transient Liquid Phase Bonding), for example, a fixing layer containing Ag is formed on the heat dissipation layer 21 and the circuit layer 23 by sputtering, and then the fixing layer is stacked in contact with the ceramic substrate 22. By pressurizing and heating the laminate, Ag diffuses into the heat dissipation layer 21 and the circuit layer 23 to lower the melting point in the vicinity of the fixing layer of the heat dissipation layer 21 and the circuit layer 23, and the ceramic substrate 22 and the heat dissipation layer 21. In addition, a molten metal layer is formed at each interface with the circuit layer 23. Further, as the diffusion proceeds, the Ag concentration of the molten metal layer decreases and the melting point increases to solidify, and the ceramic substrate 22, the heat dissipation layer 21, and the circuit layer 23 are joined.

  As shown in FIG. 1, the heat radiation layer 21 is formed with a plurality of recesses 21 b having an outer edge portion 21 a raised from the surface. The recess 21b is formed in a desired shape on the heat dissipation layer 21 before being bonded to the ceramic substrate 22 by coining using a die 40 and a punch 41, for example, as shown in FIG. The height of the outer edge 21 a of the recess 21 b is preferably 50 μm or more and 150 μm or less from the surface of the heat dissipation layer 21. The recess 21a is formed in a dot shape having a diameter of about 0.4 mm, a strip shape having a width of about 0.4 mm, or the like.

  The shape of the heat sink 30 laminated on the power module substrate 20 is not particularly limited. For example, the heat sink 30 is formed by extruding aluminum (such as A6063 in JIS standard) having a relatively high strength as a structural material. In the heat sink 30, a flow path (not shown) for circulating cooling water along the length direction is formed on the back surface of the top plate 31 formed in a plate shape.

  In the heat sink 30, the top plate 31 is formed with a plurality of protrusions 31 a that are lower than the depth of the recesses 21 b provided in the heat dissipation layer 21 of the power module substrate 20 and engage with the recesses 21 b. Yes. The convex portion 31a can be formed, for example, by configuring the top plate 31 with a plate-like member and subjecting this plate-like member to sheet metal processing.

  A bonding material B is interposed in the gap 11 between the heat radiation layer 21 of the power module substrate 20 and the top plate 31 of the heat sink 30. The bonding material B is, for example, a brazing material applied to the surface of the heat dissipation layer 21, a solder foil or a brazing foil interposed in the gap 11, as shown in FIG. 3, and the thickness is larger than the height of the outer edge portion 21a. It is provided to be 100 μm or more and 200 μm or less. By laminating the power module substrate 20 provided with the bonding material B so that the convex portions 31a and the concave portions 21b are engaged with each other, the outer edge portion 21a abuts on the surface of the heat radiating plate 31 and has a predetermined size. A power module substrate unit 10 with a heat sink having a gap 11 is formed. Therefore, the gap 11 is filled with the bonding material B (see FIG. 1).

  As described above, the power module substrate unit 10 with the heat sink of the present embodiment includes the metal plate-like heat radiation layer 21 and the ceramic substrate 22 in which the plurality of recesses 21b having the outer edge portions 21a raised from the surface are formed. A power module substrate 20 and a heat sink 30 including a metal plate-like top plate 31 having a plurality of convex portions 31a that are lower than the depth of the concave portions 21b and engage with the concave portions 21b. ing.

  The power module substrate 20 and the heat sink 30 engage a plurality of sets of concave portions 21b and convex portions 31a and bring the outer edge portion 21a into contact with the surface of the top plate 31. Laminated with a gap 11 between them. Further, a bonding material B is interposed between the heat radiation layer 21 of the power module substrate 20 and the top plate 31 of the heat sink 30.

  While the height of the outer edge portion 21 a is 50 μm or more and 150 μm or less from the surface of the heat dissipation layer 21, the thickness of the bonding material B is 100 μm or more and 200 μm or less, so that the gap 11 between the power module substrate 20 and the heat sink 30 is formed. Is in a state where a sufficient amount of the bonding material B is filled.

  The power module substrate unit 10 with the heat sink configured as described above is transported in a state where the heat radiation layer 21 of the power module substrate 20 and the top plate 31 of the heat sink 30 are temporarily joined with a solvent or the like. There is a case. In such a case, since the bonding force between the power module substrate 20 and the heat sink 30 is weak, the bonding position may be shifted due to vibration during transportation or the like. However, the power module substrate unit 10 with the heat sink of the present invention has a recess 21b. And the protrusion 31a are engaged with each other, so that the shift is unlikely to occur.

  The power module substrate unit 10 with the heat sink configured as described above is formed by bonding the power module substrate 20 and the heat sink 30 using the bonding material B, as shown in FIG. 50. In the power module substrate 50 with a heat sink, a plurality of outer edge portions 21 a protruding from the surface of the heat radiation layer 21 of the power module substrate 20 are in contact with the surface of the top plate 31. The distance from the top plate 31 is uniform. For this reason, shortage of the partial bonding material B or the like is unlikely to occur, and the heat sink 30 and the power module substrate 20 are securely bonded to each other at an accurate position.

  In addition, as a brazing method used for joining the heat radiation layer 21 and the top plate 31, a vacuum brazing method performed in a vacuum without using a flux, or a nocolok brazing method using a flux without requiring a vacuum atmosphere. It has been known. The Nocolok brazing method is a brazing method in which fluoride flux is applied to the brazing material surface to remove the oxide on the brazing material surface and heated in a non-oxidizing atmosphere for joining. Unnecessary and relatively easy and stable brazing is possible. In this case, since the flux is quickly discharged to the outside through a gap formed between the heat radiation layer 21 and the top plate 31 of the heat sink 30 at the time of joining, generation of voids and the like can be prevented.

  As described above, according to the present invention, the relative position between the heat dissipation layer and the top plate is stabilized by the engagement of the concavo-convex shape. For example, when the power module substrate and the heat sink are temporarily joined and moved, etc. Misalignment is prevented, and a unit with good workability and positioning is realized. In addition, since a uniform gap is formed between the heat dissipation layer and the top plate, it is possible to prevent the bonding material such as the brazing material from being partially insufficient or protruding, and the heat sink is bonded reliably and accurately. A power module substrate with a heat sink can be realized.

  In addition, this invention is not limited to the thing of the structure of the said embodiment, In a detailed structure, it is possible to add a various change in the range which does not deviate from the meaning of this invention.

  The shape of the convex part 31a provided in the top plate 31 of the heat sink 30 is not limited to the said embodiment, A various structure is employable. For example, when the heat dissipation layer 21 and the heat sink 30 are joined by soldering, as shown in FIG. 5, a spot-like recess 21c having a diameter of about 0.4 mm is formed in the heat dissipation layer 21, and the recess 21c corresponds to the recess 21c. A point-like recess 31b having a diameter of about 0.4 mm is also formed on the top plate 31, and a Ni or Cu ball 42 having a diameter of about 0.4 mm is disposed so as to engage with the recesses 21c and 31b. Good.

  Alternatively, when the heat dissipation layer 21 and the heat sink 30 are joined by brazing, as shown in FIG. 6, a band-shaped recess 21d is formed in the heat dissipation layer 21, and the band-shaped recess 31c corresponding to the recess 21d is formed on the ceiling. A configuration in which the aluminum wire 43 is engaged with the recesses 21d and 31c can also be adopted by forming the plate 31.

  In the above embodiment, the heat dissipation layer 21 and the top plate of the heat sink 30 are bonded with the brazing material as the bonding material B. However, the bonding material B may be other than the brazing foil, the solder foil, and the like. For example, as shown in FIG. 7, a clad material of a brazing material 32 and an aluminum material 33 is used for the top plate 34 of the heat sink 30, and the brazing material 32 of the clad material is used as a joining material, thereby arranging the joining material. The process to perform can be omitted and workability can be improved. Also in this case, the convex part 34a engaged with the concave part 21b of the heat radiation layer 21 can be formed on the clad material (top plate 34) by sheet metal processing or the like.

DESCRIPTION OF SYMBOLS 10 Power module substrate unit with heat sink 11 Crevice 20 Power module substrate 21 Heat radiation layer 21a Outer edge portion 21b, 21c, 21d Concavity 22 Ceramic substrate 23 Circuit layer 30 Heat sink 31, 34 Top plate 31a, 34a Convex portion 31b, 31c Concavity 32 Brazing material 33 Aluminum material 40 Die 41 Punch 42 Ball 50 Power module substrate B with heat sink Bonding material

Claims (7)

A power module substrate in which a metal plate-like heat dissipation layer in which a plurality of recesses having outer edge portions protruding from the surface are formed and a ceramic substrate are joined;
A heat sink comprising a metal plate-like top plate having a plurality of convex portions engaging with the concave portion and having a height lower than the depth of the concave portion;
With
The power module substrate and the heat sink are engaged between the concave portion and the convex portion to bring the outer edge portion into contact with the surface of the top plate. A substrate unit for a power module with a heat sink, wherein the substrate unit is laminated with a gap therebetween.   The power module substrate unit with a heat sink according to claim 1, wherein a height of the outer edge portion of the concave portion is 50 µm or more and 150 µm or less from the surface of the heat dissipation layer.   The power module substrate unit with a heat sink according to claim 1 or 2, wherein a bonding material is interposed between the heat dissipation layer of the power module substrate and the top plate of the heat sink.   The power module substrate unit with a heat sink according to claim 3, wherein a thickness of the bonding material is 100 μm or more and 200 μm or less.   The convex portion of the top plate includes a substantially hemispherical concave portion formed on the top plate in a shape corresponding to the concave portion of the heat dissipation layer, and a ball arranged to engage with the concave portion of the top plate. 5. The power module substrate unit with a heat sink according to claim 1, wherein the power module substrate unit has a heat sink.   The convex portion of the top plate is formed by a substantially strip-shaped concave portion formed in the top plate in a shape corresponding to the concave portion of the heat dissipation layer, and a wire arranged to engage with the concave portion of the top plate. The power module substrate unit with a heat sink according to any one of claims 1 to 4, wherein the substrate unit is provided with a heat sink. A power module substrate in which a metal plate-like heat dissipation layer in which a plurality of recesses having outer edge portions protruding from the surface are formed and a ceramic substrate are joined;
A heat sink comprising a metal plate-like top plate having a plurality of convex portions engaging with the concave portion and having a height lower than the depth of the concave portion;
A bonding layer provided between the heat dissipation layer of the power module substrate and the top plate of the heat sink;
In the state where the power module substrate and the heat sink are engaged with the concave portion and the convex portion and the outer edge portion is in contact with the surface of the top plate, the heat dissipation layer of the power module substrate A power module substrate with a heat sink, wherein the top plate of the heat sink is joined.

Images