JP2004281676A - Heat radiator and its producing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process for producing a heat radiator in which machining can be carried out by a constant operation in a correction process performing plastic deformation machining while confining variation in the shape of the heat radiator within a specified range in the production stage, and a deformation capable of stabilizing the shape after deformation can be secured surely. <P>SOLUTION: As a heat radiator 10, a clad plate where the opposite sides of a substrate layer 22 is clad with plate layers is employed and the thickness of the plate layer on the bonding surface side of the insulating substrate is set smaller than that on the other side. The process for producing the heat radiator 10 comprises a rolling step (S10) for forming a clad plate 20 by hot pressing metal plates of an identical material having a different thickness laminated on the upper and lower surfaces of a core metal plate, a step (S11) for rolling and cutting the clad plate 20 after it is cooled down to room temperature and then shaping it as desired, and a correction step (S12) performing plastic deformation machining at room temperature such that it is curved to project to the bonding surface side of the insulating substrate and to the other side. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a heat sink for a semiconductor device and a method for manufacturing the same.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in a semiconductor device such as a power module mounted with an insulating substrate on which an electronic component that generates heat during operation is mounted, measures have been taken to dissipate heat so as to maintain the electronic component within a use temperature. For example, a structure is employed in which a large metal having a high thermal conductivity is bonded as a heat radiating plate to the back side of an insulating substrate on which a semiconductor element is mounted, and the heat generated on the insulating substrate is diffused and radiated.
In such a structure, the plurality of insulating substrates on which the semiconductor elements are mounted are fixed at appropriate positions on one side surface of the heat sink by soldering or the like, and one side surface of the heat sink is covered with a housing. The other side of the heat sink is fixed in contact with the cooling body.
Therefore, in order to securely adhere the semiconductor element to the heat sink and secure an effective contact area of the heat sink with the cooling body, it is desirable that the heat sink be flat in a completed state.
However, when the insulating substrate on which the semiconductor element is mounted is soldered to one side surface of the heat radiating plate, the heat radiating plate is heated to a temperature at which the solder melts, and thermally expands according to the heating temperature. When the heat radiating plate is cooled after the solder bonding, the contraction of the thermally expanded heat radiating plate bonding side of the insulating substrate after the solidification of the solder is limited, but the opposite side can be freely contracted. Since the solidification temperature of the solder is much higher than the room temperature, the amount of shrinkage between the side surface of the heat sink returned to room temperature and the opposite side surface of the heat sink is greatly different from that of the heat sink, and as shown in FIG. Is curved so as to be convex on the side where the insulating substrate 11 is bonded.
For this reason, it is difficult to effectively secure the contact area of the heat sink with the cooling body, and there is a problem that the cooling efficiency is reduced.
[0003]
On the other hand, as the characteristics of the heat sink, it is required to have a low coefficient of linear expansion together with high thermal conductivity (heat dissipation).
Among them, the linear expansion coefficient is desirably as close as possible to the linear expansion coefficient of the insulating substrate which is smaller than the linear expansion coefficient of the heat sink in order to improve the reliability of bonding with the insulating substrate on which the semiconductor element is mounted. Therefore, copper (Cu; linear expansion coefficient: 16.5 × 10 ⁻⁶ m / K) having excellent thermal conductivity is used. For the purpose of suppressing the linear expansion coefficient, molybdenum (Mo; linear expansion coefficient: 5. A material using a copper-molybdenum composite (Cu-Mo composite), which is a composite of 1 × 10 ⁻⁶ m / K), has been proposed as a heat sink material. For example, this is a technique described in Patent Document 1.
[0004]
The technique described in Patent Document 1 proposes a Cu-Mo composite material in which a composite of molybdenum and copper impregnated with molten copper in a gap between powders of a molybdenum green compact is rolled, and a method for producing the same. I have. Further, in this technique, a heat dissipating substrate material for mounting a copper clad type semiconductor, comprising a Cu / Cu-Mo composite material / Cu clad plate in which a copper plate is further pressed on both surfaces of a Cu-Mo composite material, has been proposed, which is expensive. In consideration of the balance between the performance of Mo, which is one of the metal materials, and the adoption cost, the linear expansion coefficient is maintained at a low value while suppressing the content of Mo.
[0005]
By the way, according to the technology described in Patent Document 2, the present inventor uses, as an insulating substrate on which a semiconductor element is mounted, a material in which a thermal stress generated on a bonding surface side with a heat sink is larger than a thermal stress generated on the other surface side. Adopting a three-layer clad plate that adopts the method of bonding the heat sink to the heat sink, using the fact that the bonding surface side of the insulating substrate with the heat sink becomes convex, There has been proposed a structure for removing bubbles existing in a bonding layer with a heat sink.
[0006]
[Patent Document 1]
JP 2001-358266 A [Patent Document 2]
JP-A-10-270612
[Problems to be solved by the invention]
When manufacturing a copper-clad type heat sink made of the above-mentioned Cu / Mo / Cu clad plate or Cu / Cu-Mo composite material / Cu clad plate, the thickness of the Cu layer clad on both surfaces is uniform. However, it is difficult to achieve complete uniformity, and individual products tend to vary. Due to the difference in the thickness of the Cu layer, the radiator plate in the manufacturing stage is curved to one side, and the amount of warpage (flatness) varies. Therefore, the heat sink in the manufacturing stage, which is curved to one side, is plastically deformed so that the heat sink is modified so as to be substantially flat.
However, when the amount of deformation during plastic deformation processing is small, stress release or the like occurs due to heat history, and the shape may return to the original state. In addition to this, there is variation in which one side of the heat sink in the manufacturing stage is curved. For these reasons, it is difficult to construct a repair process by plastic deformation of the heat sink in a stable curved state.
[0008]
Further, since there is a limit to the amount of change in the shape of the heat sink caused by thermal stress generated in the Cu layer clad on both sides of the copper clad heat sink, if the amount of warpage of the heat sink at a low temperature is large, heat Due to the amount of shape change of the heat sink caused by the stress, it is difficult to deform to the extent that the adhesion to the cooling part can be ensured at high temperature, and the adhesion to the cooling part cannot be ensured, resulting in a decrease in cooling efficiency. Invite.
[0009]
For these reasons, it is necessary to keep the warpage (shape) of the heatsink in the bonded state of the insulating substrate or alone in a certain range.
Therefore, in the present invention, by utilizing the thermal stress generated due to the Cu layer clad on both surfaces of the copper-clad type heat sink, variation in the shape of the heat sink at the manufacturing stage is suppressed. A method for manufacturing a radiator plate capable of performing a reliable and stable correction process on a radiator plate in a curved state within a range is proposed.
[0010]
[Means for Solving the Problems]
The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.
[0011]
That is, in claim 1, an insulating substrate on which an element is mounted is joined to one side surface, and the other side surface is a radiator plate fixed to a cooling body. A metal layer clad on the other side due to thermal stress generated between the metal layer clad on the insulating substrate bonding surface side and the substrate layer, composed of a clad plate consisting of at least three layers clad with a metal layer The thermal stress generated between the substrate and the substrate layer is increased.
[0012]
In claim 2, the thickness of the metal layer clad on one side of the substrate layer is different from the thickness of the metal layer clad on the other side.
[0013]
According to a third aspect, the metal layer clad on one side of the substrate layer and the metal layer clad on the other side have different linear expansion coefficients.
[0014]
Claim 4 is a method for manufacturing a heat sink in which an insulating substrate on which an element is mounted is bonded to one side surface and the other side surface is fixedly contacted with a cooling body. Rolling process of hot-press bonding by laminating metal plates made of different materials and having different thicknesses, forming process of cooling to room temperature and forming into a desired shape, and correcting warpage by plastic deformation at room temperature And a correction step.
[0015]
Claim 5 is a method for manufacturing a heat sink in which an insulating substrate on which elements are mounted is joined to one side surface and the other side surface is fixedly contacted with a cooling body. Rolling process of laminating metal plates made of materials with different coefficients of expansion and hot pressing, cooling process to room temperature, forming process to desired shape, and correcting deformation by plastic deformation at room temperature And a correction step.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the invention will be described.
FIG. 1 is a flowchart showing a heat sink manufacturing process according to the present invention, FIG. 2 is a side sectional view showing a state of superposed heat sink constituent materials, FIG. 3 is a side view showing a state of rolling to form a clad plate, FIG. 4 is a side view showing the clad plate after cooling, and FIG. 5 is a side view showing the heat sink after plastic deformation processing.
6A is a side view showing a state in which an insulating substrate is joined to a heat sink, FIG. 6B is a side sectional view showing a heat sink in which the insulating substrate is joined at room temperature, and FIG. FIG.
FIG. 7A is a side view showing a radiator plate fixed to a cooling body at room temperature, and FIG. 7B is a side view showing a radiator plate fixed to the cooling unit when the element generates heat.
8A is a side view showing a state in which an insulating substrate on which a semiconductor element is mounted is soldered to a heat sink, and FIG. 8B is a side view showing a heat sink in which the insulating substrate on which the semiconductor element is mounted is connected via a solder layer. It is.
[0017]
First, the radiator plate 10 according to the present invention will be described.
As shown in FIG. 5, the heat dissipation plate 10 is a clad plate having at least three layers, and both surfaces of a substrate layer 22 which is made of a material having a relatively small coefficient of linear expansion and serves as a core material have relatively high thermal conductivity. This is clad with plate layers 21 and 23 made of a high material. Due to the structure of the heat radiating plate 10, the thermal stress generated between the substrate layer 22 and the plate layer 21 and the thermal stress generated between the substrate layer 22 and the plate layer 23 are different from each other. And
[0018]
An insulating substrate 11 on which the semiconductor element 18 is mounted is soldered to one side surface (hereinafter, referred to as “upper surface”) of the heat radiating plate 10, and the other side surface (hereinafter, referred to as “lower surface”) of the heat radiating plate 10 When the plate 10 is fixed to the cooling body 16 by a fastening member such as a bolt, the plate 10 contacts the cooling body 16 via the grease layer.
Then, when the temperature is raised / heated or cooled in the same state, the upper surface of the radiator plate 10 is clad between the plate layer 21 (hereinafter referred to as “upper plate layer 21”) and the substrate layer 22. Due to the generated thermal stress, the thermal stress generated between the substrate layer 23 (hereinafter, referred to as “lower substrate layer 23”) clad on the lower surface side of the heat sink 10 and the substrate layer 22 is relatively large. It is set so as to apply a force to the heat radiating plate 10 to bend to the lower surface side when expanded, and to apply a force to the heat radiating plate 10 to bend to the upper surface side when contracted. .
[0019]
In the present embodiment, the thermal stress generated between the substrate layer 22 and the upper plate layer 21 is different from the thermal stress generated between the substrate layer 22 and the lower plate layer 23. For this purpose, the same material is used for both the plate layers 21 and 23, and the lower plate layer 23 is formed so as to have a large thickness.
Thereby, the thermal stress generated between the lower coated layer 23 and the substrate layer 22 becomes larger than the thermal stress generated between the upper coated layer 21 and the substrate layer 22, and the radiating plate at the time of expansion is increased. A bending load is applied to the heat radiating plate 10 when it is contracted, and a bending load is applied to the heat radiating plate 10 when it contracts.
In this case, the thicknesses of the plate layers 21 and 23 need to be determined so that the heat radiating plate 10 (cladding plate 20) is always curved to one side due to a difference in generated thermal stress.
[0020]
However, the form of the heat radiating plate 10 is not limited to the present embodiment. In order to generate thermal stress in the heat radiating plate 10, materials having different linear expansion coefficients between the upper plate layer 21 and the lower plate layer 23 are used. Can be selected so that the lower plate layer 23 has a larger linear expansion coefficient than the upper plate layer 21. As described above, the thermal stress generated between the upper cover layer 21 and the substrate layer 22 differs from the thermal stress generated between the lower cover layer 23 and the substrate layer 22 due to the difference in the coefficient of linear expansion for each material. be able to.
In this case, it is necessary to select the material of the plate layers 21 and 23 so that the heat radiating plate 10 (cladding plate 20) is necessarily curved to one side due to a difference in generated thermal stress.
[0021]
Next, a method for manufacturing the above-described heat radiating plate 10 will be described with reference to the flowchart of FIG.
The manufacturing process generally includes a rolling process (S10), a forming process (S11), and a correcting process (S12).
[0022]
First, the rolling step (S10) will be described.
As shown in FIG. 2, a metal plate 22 ′ serving as a core material of the radiator plate 10 and constituting a substrate layer 22 made of a material having a relatively low coefficient of thermal expansion, and an upper clad on the upper surface side of the substrate layer 22. A metal plate 21 'for forming the plate layer 21 and a metal plate 23' for forming the lower plate layer 23 clad on the lower surface side of the substrate layer 22 are laminated, and rivets 24 and the like are stacked. It is fixed by penetrating (S10a).
The three metal plates 21 ′, 22 ′, and 23 ′ fixed in this manner are held in an electric furnace in a hydrogen atmosphere heated to a pressing temperature, and the respective metal plates 21 ′, 22 ′ and 23 ′ are fixed. Heat until 23 ′ reaches the pressure bonding temperature (S10b).
Then, as shown in FIG. 3, the heated three metal plates 21 ', 22', 23 'are passed through a rolling mill and hot-pressed (S10c), and the metal plate 21' and the metal plate 22 'are pressure-bonded. At the same time, the metal plate 23 'and the metal plate 22' are pressure-bonded to form the three-layer clad plate 20.
[0023]
Next, the molding step (S11) will be described.
The clad plate 20 formed as described above is naturally cooled (S11a). At this time, the coefficient of linear expansion of the substrate layer 22 is smaller than that of the plate layers 21 and 23 clad on the upper and lower surfaces of the clad plate 20, so that the distance between the upper plate layer 21 and the substrate layer 22 and the lower plate Thermal stress is generated between the layer 23 and the substrate layer 22. However, since the layer thicknesses of the plate layers 21 and 23 are different from each other, a difference occurs in the thermal stress acting on the upper surface and the lower surface of the substrate layer 22. As a result, the heat sink 10 may be bent to the upper surface side. Force acts. Accordingly, as shown in FIG. 4, the clad plate 20 cooled to room temperature is curved so as to project toward the upper cover layer 21 side, and forms a cylindrical curved surface.
[0024]
The amount of warpage of the clad plate 20 at this time is D _0, and the value of the amount of warp D ₀ is positive when the clad plate 20 is convex on the upper surface side (joining surface side of the insulating substrate 11), and the value of the clad plate 20 is on the lower surface side. When it is convex (on the side facing the cooling body 16), it is regarded as negative.
In the clad plate 20 of the present embodiment, since the upper plate layer 21 and the lower plate layer 23 have different layer thicknesses, they always curve to one side, and the lower plate layer 23 has a larger layer thickness. The clad plate 20 always has a shape that is convexly warped to the upper surface side. That is, it is possible to eliminate the variation in the warping direction (curving direction) of the clad plate 20.
[0025]
Further, the difference between the thermal stress generated between the clad plate 20 and the upper plate layer 21 during expansion or contraction and the thermal stress generated between the clad plate 20 and the lower plate layer 23 is determined by It is possible to control to some extent by the layer thicknesses of 21 and 23. Thus, during inflation or during contraction, it is possible to some extent control the bending load acting on the cladding plate 20, it becomes possible to control within a certain range warpage D ₀ of the clad plate 20.
Warpage D ₀ is the time of plastic deformation at room temperature to be described later, without returning to the original state by heat history, and, the amount of deformation that can be stably maintained in the form of the deformed ( "guaranteed amount of deformation ) Is controlled so as to fall within the range in which the value can be added.
That is, warpage _{D 0,} a positive value, it is preferably controlled to be within a certain range _{(α max ≧ D 0 ≧ α} min> 0). Note that the values of α _max and α _min differ depending on the material, thickness, and the like of the substrate layer 22 and the plate layers 21 and 23, and thus are set according to the material used.
[0026]
Subsequently, after performing surface treatment to remove oxides and the like on the surface of the clad plate 20, rolling is repeated (S11b) to obtain the clad plate 20 having a predetermined thickness. Then, the clad plate 20 is cut (S11c) and formed into a predetermined size of the heat sink 10.
[0027]
Next, the correcting step (S12) will be described.
In the correction step (S12), the clad plate 20 formed into the size of the heat sink 10 in the forming step (S11) is subjected to plastic deformation at room temperature to correct the amount of warpage (flatness) of the clad plate 20, The heat sink 10 is used (S12a).
In the plastic deformation processing, the clad plate 20 which is convex on the upper surface side is deformed so as to be substantially flat or convex on the lower surface side. Therefore, as shown in FIG. 5, the manufactured radiator plate 10 is in a state in which the radiator plate 10 is warped in a substantially flat surface or a lower surface side.
At this time, the amount of warpage of the heat sink is D, and when it is convex on the upper surface side (joining side of the insulating substrate 11), it is positive, and when it is convex on the lower surface side, it is negative. That is, the cladding plate 20 of warpage D ₀ is the heat sink 10 of warpage D via the plastic deformation, warpage D at this time is formed so as to be zero or negative value.
[0028]
In this plastic deformation processing, since the warping direction of the clad plate 20 is constant, the applied deformation directions are unified. That is, the warp amount D ₀ of the clad plate 20 is always set to a positive value, and the warp amount D is zero or a negative value by applying a load pressing the clad plate 20 from the upper surface side. The heat sink 10 is used.
Further, the amount of warp D of the heat sink 10 is such that when the shape of the heat sink changes due to thermal stress at the time of heat generation of the element, the heat sink has such a shape that the adhesion to the cooling body can be secured. value and is defined, therefore, in the plastic deformation process, the shape variation of the warp amount D from warpage D ₀ is substantially constant.
Further, as described above, warpage D ₀ of the clad plate 20, because it is a value within a range capable of providing a guaranteed amount of deformation, clad plate 20 after being deformed by plastic deformation (i.e. radiator plate The shape of 10) becomes stable.
[0029]
In this way, the plastic deformation processing can be made substantially constant processing through the product, and furthermore, it is possible to reliably secure the amount of deformation that can stabilize the shape after the deformation. A simple repairing step (S12) can be constructed, and through this repairing step (S12), the heat sink 10 can be formed stably at room temperature and in a substantially flat shape or a state in which it is warped to the lower surface side. it can.
[0030]
The insulating substrate 11 on which the semiconductor element 18 is mounted is joined to the upper surface of the heat sink 10 manufactured by the above manufacturing process.
As shown in FIG. 6A, the insulating substrate 11 on which the semiconductor element 18 is mounted is placed on the upper surface of the heat sink 10 via the solder foil 12 '. Then, the heat sink 10 and the insulating substrate 11 are soldered in a known soldering process.
[0031]
In the bonding step between the heat radiating plate 10 and the insulating substrate 11, the heat radiating plate 10 expands while the insulating substrate 11 and the heat radiating plate 10 are being heated.
At this time, the heat radiating plate 10 whose warpage D was zero or a negative value before the heat radiating substrate 11 was joined is acted on by a force acting to bend in a downwardly convex direction. As shown in ()), it is in a state of being convexly warped to the lower surface side, and the amount of warp D has a negative value.
[0032]
Then, when the step of joining the heat sink 10 and the insulating substrate 11 is completed, the heat sink 10 is cooled to room temperature.
In the cooling process of the heat radiating plate 10, the solder joint on the upper surface of the heat radiating plate 10 that has thermally expanded is restricted from shrinking after the solidification of the solder 12, but the lower surface can be freely contracted. Since the solidification temperature of the solder 12 is much higher than the normal temperature, the amount of shrinkage between the upper surface and the lower surface of the heat radiating plate 10 that has returned to the normal temperature is greatly different. It curves to be convex. Therefore, as shown in FIG. 6C, the normal-temperature radiator plate 10 to which the substrate 11 is joined is in a state of being convexly warped to the upper surface side, and the warp amount D is a positive value.
[0033]
If the heat radiating plate 10 has a convex shape on the lower surface side at room temperature before the bonding of the insulating substrate 11 (the amount of warpage D is a negative value), the heat radiating plate 10 has a planar shape (the amount of warping D is zero). ), It is possible to suppress the amount of warpage in which the normal-temperature radiator plate 10 to which the insulating substrate 11 is bonded is convex on the upper surface side.
[0034]
As shown in FIG. 7A, the radiator plate 10 at room temperature to which the substrate 11 is joined as described above is fixed to the cooling body 16 with a fastening member such as a bolt. A heat radiation grease 15 is interposed between the heat radiation plate 10 and the cooling body 16. At this time, the amount of warp D is a positive value in a state where the heat radiating plate 10 warps convexly to the upper surface side, and the lower surface of the heat radiating plate 10 faces the cooling body 16.
When the semiconductor element 18 operates to generate heat and is at a high temperature, a force is generated by the thermal stress so as to bend the heat radiation plate 10 so as to be convex toward the lower surface side. As shown in the figure, the heat radiating plate 10 is in a state of being slightly convexly warped downward, and the amount of warping D is a negative value.
[0035]
As described above, when the semiconductor element 18 operates and generates heat, the heat radiating plate 10 is warped to the cooling body 16 side, and the gap between the cooling body 16 and the heat radiating plate 10 is narrow. Therefore, the layer of the heat radiation grease 15 in this portion is thin, and the thermal resistance is small. Further, only by pressing the heat radiating plate 10 against the cooling body 16, the layer of the heat radiating grease 15 between the heat radiating plate 10 and the cooling body 16 can be thinned, and the air in the heat radiating grease 15 can be easily removed. Since it can be extruded, bubbles in the heat radiation grease 15 are prevented from remaining, and an increase in thermal resistance due to the heat radiation grease 15 and the bubbles can be prevented. As described above, improvement of the cooling performance of the semiconductor element 18 by the cooling body 16 is expected.
[0036]
Next, examples of materials suitable for applying the method for manufacturing a heat sink of the present invention will be described.
[0037]
As the clad plate 20 constituting the heat sink 10, a Cu / Mo / Cu clad plate or Cu / Cu in which both surfaces of molybdenum (Mo) or a copper-molybdenum composite (Cu-Mo composite) are clad with copper (Cu). -Mo composite / Cu clad plate is adopted. In this case, the metal plate 22 'serving as the substrate layer 22 of the clad plate 20 is Mo or a Cu-Mo composite material, and the metal plates 21' and 23 'serving as the plate layers 21 and 23 are Cu.
When the clad plate 20 is a Cu / Cu-Mo composite / Cu clad plate, the pressing temperature in the rolling step (S10) is about 800 ° C., and the clad plate 20 is a Cu / Mo / Cu clad plate. , The pressing temperature in the rolling step (S10) is 850 ° C. or higher.
Cu has a high thermal conductivity and is suitable as a material for a heat sink. In addition, the Mo or Cu-Mo composite material has a smaller linear expansion coefficient than Cu due to the presence of Mo, and in addition to this, the Cu-Mo composite material is higher than Mo alone by using a composite material with Cu. Has thermal conductivity.
For these reasons, by using a Cu / Mo / Cu clad plate or a Cu / Cu-Mo composite / Cu clad plate as the clad plate 20, a good heat sink 10 can be formed.
[0039]
The Cu-Mo composite material is formed by pressing and shaping molybdenum powder having an average particle size of 2 to 5 × 10 ⁻⁶ m at a pressure of 100 to 200 MPa to form a molybdenum green compact, and between the powders of the molybdenum green compact. And obtained by impregnating molten copper at 1200 ° C. to 1300 ° C. in a non-oxidizing atmosphere. Further, the Cu-Mo composite is subjected to primary rolling to form a plate, which is used as a core metal plate 22 ′ for manufacturing the heat sink 10. In the composition of the Cu—Mo composite material, the proportion of Mo is 70 to 60% by weight, and the rest is Cu.
[0040]
【The invention's effect】
The present invention is configured as described above, and has the following effects.
[0041]
That is, as set forth in claim 1, an insulating substrate on which the element is mounted is joined to one side surface, and the other side surface is a radiator plate fixed to a cooling body. Is composed of a clad plate consisting of at least three layers clad with a metal layer, and a metal clad on the other surface side due to thermal stress generated between the metal layer clad on the insulating substrate bonding surface side and the substrate layer. Since the thermal stress generated between the layer and the substrate layer is increased, it becomes possible to control the direction of the bending load acting on the heat sink when the heat sink expands or contracts.
[0042]
As shown in claim 2, the thickness of the metal layer clad on one side of the substrate layer and the thickness of the metal layer clad on the other side are made different, so that the heat radiating plate expands or contracts when the heat radiating plate expands or contracts. It is possible to control the direction of the bending load that acts.
[0043]
As described in claim 3, since the metal layer clad on one side of the substrate layer and the metal layer clad on the other side have different coefficients of linear expansion, heat is radiated when the heat sink expands or contracts. It is possible to control the direction of the bending load acting on the plate.
[0044]
As described in claim 4, a method of manufacturing a heat sink in which an insulating substrate on which elements are mounted is joined to one side surface and the other side surface is fixedly contacted with a cooling body. Rolling steps of laminating metal plates made of the same material and having mutually different thicknesses, a rolling step of performing hot pressing, a cooling step of cooling to room temperature, and forming into a desired shape, and a warping amount by plastic deformation processing at room temperature. Since the heat radiating plate before the forming step is always warped in one direction, the heat radiating plate before the forming step can be reliably and stably subjected to plastic deformation processing.
[0045]
As described in claim 5, a method of manufacturing a heat sink in which an insulating substrate on which elements are mounted is joined to one side surface and the other side surface is fixedly contacted with a cooling body. A metal sheet made of a material having a different expansion coefficient is laminated, and a rolling step of performing hot pressing, a cooling step of cooling to room temperature, and a forming step of forming into a desired shape, and a warping amount by plastic deformation processing at room temperature. Since the heat radiating plate before the forming step is always warped in one direction, the heat radiating plate before the forming step can be reliably and stably subjected to plastic deformation processing.
[Brief description of the drawings]
FIG. 1 is a flowchart showing a heat sink manufacturing process according to the present invention.
FIG. 2 is a side cross-sectional view showing a state of a heat sink constituent material that is superimposed.
FIG. 3 is a side view showing a state in which a clad plate is formed by rolling.
FIG. 4 is a side view showing the clad plate after cooling.
FIG. 5 is a side view showing the heat sink after plastic deformation processing.
6A is a side view showing a state in which an insulating substrate is joined to a heat sink, FIG. 6B is a side sectional view showing a heat sink in which the insulating substrate is joined at room temperature, and FIG. The side view which shows a board.
7A is a side view showing a radiator plate fixed to a cooling body at a normal temperature, and FIG. 7B is a side view showing a radiator plate fixed to the cooling unit when the element generates heat.
8A is a side view showing a state in which an insulating substrate on which a semiconductor element is mounted is joined to a heat sink by soldering; FIG. 8B is a side view showing a heat sink in which the insulating substrate on which the semiconductor element is mounted is joined via a solder layer; FIG.
[Explanation of symbols]
S10 Rolling process S11 Forming process S12 Modification process 10 Heat sink 11 Insulating substrate 20 Clad plate 21 Covered layer 21 'Metal plate 22 Substrate layer 22' Metal plate 23 Covered layer 23 'Metal plate

Claims (5)

An insulating board on which the element is mounted is joined to one side, and the other side is a heat sink that is fixedly contacted with a cooling body,
The heatsink is constituted by a clad plate composed of at least three layers in which both surfaces of a substrate layer serving as a core material are clad with a metal layer, and is generated between the metal layer clad on the insulating substrate bonding surface side and the substrate layer. A heat radiating plate wherein thermal stress generated between a metal layer clad on the other surface side and a substrate layer is larger than thermal stress. The heat sink according to claim 1, wherein a thickness of the metal layer clad on one side of the substrate layer is different from a thickness of the metal layer clad on the other side of the substrate layer. 2. The heat sink according to claim 1, wherein the metal layer clad on one side of the substrate layer and the metal layer clad on the other side have different coefficients of linear expansion. A method for manufacturing a radiator plate in which an insulating substrate on which elements are mounted is joined to one side and the other side is fixedly contacted with a cooling body,
Rolling step of laminating metal plates made of the same material and having different thicknesses on the upper and lower surfaces of the metal plate serving as the core material and performing hot pressing,
After cooling to room temperature, a molding step of molding into a desired shape,
A process of correcting the amount of warpage by plastic deformation at room temperature. A method for manufacturing a radiator plate in which an insulating substrate on which elements are mounted is joined to one side and the other side is fixedly contacted with a cooling body,
Rolling step of laminating metal plates made of materials having different expansion coefficients from each other on the upper and lower surfaces of the metal plate serving as the core material and performing hot pressing,
After cooling to room temperature, a molding step of molding into a desired shape,
A process of correcting the amount of warpage by plastic deformation at room temperature.

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