JP2008041756A - Manufacturing method of electronic apparatus, and the electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an electronic component from becoming high in temperature by efficiently transferring heat from the electronic component to a heat accumulating body. <P>SOLUTION: The apparatus is configured by assembling a metal substrate 4 mounted with an electronic component 5 of an electronic apparatus 1, an elastic bag 6 having a heat accumulating body 7 sealed therein, and a lower container 3 as a base, having a surface 3b for placing the bag 6 and a protrusion 3a protruding from the surface 3b and supporting the metal substrate 4 so as to oppose the surface 3b. In this case, the bag 6 is placed on the surface 3b of the lower container 3, the metal substrate 4 is placed on the protrusion 3a, the bag 6 is attached tightly on the metal substrate 4 over a region 4a of the metal substrate 4, where the electronic component 5 is mounted, while the bag 6 is made to press against the surface 3b with the metal substrate 4, and the protrusion 3a and the metal substrate 4 are fastened with screws 8 and fix them. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electronic device including electronic components such as a power transistor, a microprocessor, a choke coil, a laser diode, and an electric motor, and a method for manufacturing the electronic device, and particularly, when the electronic component operates and generates heat, the temperature becomes high. It is related to suppressing this.

  Some electronic devices include electronic components that generate heat and become high temperature when operated, such as a power transistor, a microprocessor, a choke coil, a laser diode, and an electric motor. When such an exothermic electronic component reaches a temperature higher than a predetermined temperature, the electronic component or the electronic device malfunctions, and further, damage such as destruction of the built-in circuit or peripheral circuit of the electronic device occurs. In order to prevent the occurrence of such harm, various measures have been proposed in the past for suppressing the temperature of electronic components from becoming high.

  For example, in Patent Document 1 below, cooling is performed by enclosing a metal having a melting point lower than the melting point or decomposition temperature of the hollow container and lower than the upper limit operating temperature of the electronic component inside the hollow container formed of a high thermal conductivity material. By attaching the element to the surface opposite to the circuit board of the electronic component mounted on the circuit board, the heat generated from the electronic component is absorbed and stored by self-melting of the metal, preventing the electronic component from becoming hot. is doing.

In Patent Document 2 below, Al ₂ O ₃ having a circuit pattern formed on the upper surface is used.
In a circuit board composed of an insulating plate made of a member and a substrate made of an aluminum member in close contact with the lower surface of the insulating plate, an electronic component is mounted on the upper surface of the insulating plate and sealed with respect to the entire surface of the substrate. By encapsulating a heat storage material made of a paraffin member in such a hollow portion, heat generated from the electronic component is absorbed by self-melting of the heat storage material to store the heat, and the electronic component is prevented from reaching a high temperature.

  Further, in Patent Document 3 below, a heat dissipation sheet formed by laminating a metal sheet such as aluminum or copper and an adhesive heat conductive member containing a heat softening material such as paraffin wax is used as an electronic component and a heat The metal sheet is connected to the electronic component, and the heat conductive member is connected to the heat dissipating member, and the heat generated from the electronic component is transferred from the solid to the liquid of the heat conductive member. The change absorbs heat and transmits it to the heat dissipating member to suppress the electronic component from becoming high temperature.

  Furthermore, in Patent Document 4 below, a slurry in which a phase-changing substance is encapsulated in a small amount is encapsulated in a flexible bag, and the bag is brought into contact with the electronic component. The change absorbs heat and stores heat, and the electronic component is prevented from becoming high temperature.

JP 2004-152905 A Japanese Patent No. 2798656 JP 2002-305271 A US Patent No. 5007478

  As described above, conventionally, by attaching a heat storage body such as metal, paraffin, or slurry directly to the electronic component or via the metal, the heat generated from the electronic component is released to the heat storage body, and the electronic component becomes hot. It was suppressed. However, if a gap containing air is formed between the electronic component and the heat storage body, the heat conductivity of the air is low, so the heat generated from the electronic component is efficiently released to the heat storage body, and the electronic component becomes hot. It becomes impossible to suppress becoming.

  The present invention solves the above-described problems, and the problem is to efficiently prevent the heat generated from the electronic component from escaping to the heat storage body and to prevent the electronic component from reaching a high temperature. .

  An electronic device manufacturing method according to the present invention includes a metal substrate on which an electronic component is mounted, a stretchable bag enclosing a heat storage body, a surface on which the bag is placed, a metal projecting from the one surface and facing the one surface. A method of manufacturing an electronic device including a base having a protrusion that supports a substrate, wherein a bag is placed on one surface of the base, a metal substrate is placed on the protrusion, and the metal substrate is pressed against the entire surface of the metal substrate. The bag is brought into close contact with the metal substrate over the region where the component is mounted, and the protrusion and the metal substrate are fixed. About the inside of a bag, it is preferable to fill with a heat storage body so that air may not enter, and to make it a vacuum state.

  If it does in this way, the bag which enclosed the thermal storage body can be pinched | interposed with a metal board | substrate and a base, and the space | gap containing air can be made to adhere to the metal board | substrate over the area | region which mounted the electronic component of a metal board | substrate. . That is, the adhesion between the electronic component and the heat storage body via the metal substrate and the bag can be increased. For this reason, when the electronic component operates and generates heat, it is possible to efficiently release the heat from the electronic component to the heat storage body through the metal substrate and the bag, and to suppress the electronic component from becoming high temperature. Become. In addition, since the bag has elasticity, even if the volume changes due to the phase change between the solid and liquid of the heat storage body, the bag expands and contracts following the change, rupture of the bag, The escape of the heat storage body and the generation of bubbles in the bag can be prevented. For this reason, it is possible to stably and efficiently release heat generated from the electronic component to the heat storage body, and to keep the electronic component from becoming high temperature.

  In one embodiment of the present invention, the protrusion of the base is composed of two parallel walls that support the region outside the region where the electronic component of the metal substrate is mounted, the bag is inserted between the protrusions, and the metal substrate is The bag is placed on the protrusion and pressed against the one surface of the base and the side surface of the protrusion with the metal substrate, and the bag is brought into close contact with the metal substrate over the region where the electronic component of the metal substrate is mounted, thereby fixing the protrusion and the metal substrate.

  In this way, the bag and the heat storage body expand in a direction perpendicular to the wall surface of the protrusion when the bag is pressed with the metal substrate, or when the electronic device is shaken or tilted, On the other hand, it is possible to reliably prevent the protrusion from shifting in a direction perpendicular to the protrusion. For this reason, it becomes possible to keep the bag firmly and stably adhered to the metal substrate over the mounting region of the electronic component on the metal substrate.

  In one embodiment of the present invention, the protrusion of the base is composed of four or more pillars that support a region outside the region where the electronic component of the metal substrate is mounted, and whose side surface is formed in a curved shape. Insert between the protrusions, place the metal substrate on the protrusions, and press the bag against one side of the base and the side of the protrusion with the metal substrate, and make the bag adhere to the metal substrate over the area where the electronic parts of the metal substrate are mounted Fix the protrusion and metal substrate.

  In this way, the bag and the heat storage body expand in a direction perpendicular to the side surface of the protrusion when the bag is pressed with the metal substrate, or when the electronic device is shaken or tilted, On the other hand, it is possible to reliably prevent the protrusion from shifting in a direction perpendicular to the protrusion. Moreover, since the side surface of the protrusion is formed in a curved surface shape, the bag can be prevented from being damaged due to contact with the protrusion. For this reason, it becomes possible to keep the bag firmly and stably adhered to the metal substrate over the mounting region of the electronic component on the metal substrate.

  Further, in one embodiment of the present invention, a convex portion is provided on one surface of the table or a portion that contacts the bag of the metal substrate, and the bag is mounted on one surface of the table so that the convex portion bites into the bag, and the metal substrate is mounted on the protrusion. .

  In this case, the bag and the heat accumulator that are in close contact with the metal substrate over the mounting region of the electronic component on the metal substrate can be reliably prevented from being displaced by the convex portion, and the close contact state between the metal substrate and the bag can be prevented. It becomes possible to maintain it stably. In addition, by providing a convex part on one surface of the table placed above the bag or in contact with the center of the metal substrate bag, even if air bubbles are generated in the bag, the convex part lowers the center of the bag. The air bubbles in the bag can be driven into a region outside the mounting region of the electronic component on the metal substrate. For this reason, the air gap between the metal substrate and the heat storage body is further reduced, and it is possible to efficiently release the heat generated from the electronic component to the heat storage body and suppress the electronic component from becoming high temperature. .

  In addition, an electronic device according to the present invention includes a metal substrate on which an electronic component is mounted, a stretchable bag enclosing a heat storage body, a surface on which the bag is placed, a metal substrate so as to protrude from the one surface and face the one surface. The metal substrate is fixed by supporting the region outside the region where the electronic component is mounted, supported by the projection of the table, and the bag is inserted between the projections by the metal substrate. While being pressed against one surface of the base and the side surface of the protrusion, the metal substrate is in close contact with the region where the electronic component of the metal substrate is mounted.

  In this way, the bag enclosing the heat accumulator is sandwiched between the metal substrate and the base, and is in close contact with the metal substrate so that there is less air gap between the metal substrate and the electronic component mounting region. Therefore, when the electronic component operates and generates heat, it is possible to efficiently release the heat generated from the electronic component to the heat storage body through the metal substrate and the bag, and to suppress the electronic component from becoming high temperature. . In addition, the bag and the heat storage body expand in a direction perpendicular to the protrusion when the bag is pressed with a metal substrate, or shift in a direction perpendicular to the protrusion when the electronic device is shaken. This can be prevented by the protrusion, and the bag can be kept securely and stably adhered to the metal substrate over the region where the electronic component of the metal substrate is mounted. Furthermore, even if the volume changes due to the phase change between the solid and liquid of the heat storage body, the bag expands and contracts following the change, so that the bag bursts, the heat storage body escapes from the bag, and The generation of bubbles can be prevented, and the heat generated from the electronic component can be released to the heat storage body stably and efficiently, and the electronic component can be kept from becoming high temperature.

  According to the present invention, the bag enclosing the heat storage body is sandwiched between the metal substrate and the base, and the metal substrate is closely attached to the metal substrate so that there is less gap in the air over the region where the electronic component is mounted. Therefore, when the electronic component operates and generates heat, it is possible to efficiently release the heat from the electronic component to the heat storage body through the metal substrate and the bag, and to suppress the electronic component from becoming high temperature. It becomes.

  1 and 2 are longitudinal sectional views of an electronic apparatus 1 according to an embodiment of the present invention. The upper container 2 and the lower container 3 of the electronic device 1 are formed of a metal material having thermal conductivity and heat dissipation such as aluminum. A metal substrate 4, an electronic component 5, a bag 6, and a heat storage body 7 are provided inside the containers 2 and 3. The metal substrate 4 is formed of a metal material having thermal conductivity such as aluminum. An electric circuit is formed on the surface of the metal substrate 4. An electronic component 5 is mounted on the center of the upper surface of the metal substrate 4 by surface mounting or the like. The electronic component 5 is composed of an electronic component having a heat generating property such as a power transistor, a microprocessor, a choke coil, a laser diode, or an electric motor, which generates heat and becomes high temperature when operated.

  The bag 6 is made of a stretchable and airtight material such as a laminate film. A heat storage body 7 is sealed in the bag 6. Polyvinyl chloride (PVC) can be used as the material for the bag 6. The heat storage body 7 is made of a material, such as paraffin wax, that absorbs heat and stores heat during phase change from solid to liquid (melting). The melting point of the heat accumulator 7 is lower than the melting point of each material of the containers 2 and 3 and the metal substrate 4 or the decomposition temperature of the containers 2 and 3 and below the upper limit operating temperature of the electronic component 5. As a specific example of the heat storage body 7, a synthetic wax FT115 manufactured by Nippon Seiwa Co., Ltd. can be used. The melting point of this synthetic wax is 114 ° C. About the inside of the bag 6, it is preferable to fill with the heat storage body 7 so that air may not enter, and to make it a vacuum state.

  Inside the lower container 3, there are provided a surface (inner bottom surface) 3 b on which the bag 6 is placed, and a protrusion 3 a that vertically protrudes upward from the surface 3 b and supports the metal substrate 4 so as to face the surface 3 b. Yes. The protrusion 3a is composed of, for example, two parallel walls as shown in FIG. The side surfaces at both ends of the protrusion 3a in FIG. 3 are formed in a curved shape. In addition to this, the protrusion 3a may be composed of, for example, four or more columns as shown in FIG. The side surface of the protrusion 3a in FIG. 4 is formed in a curved surface shape. 3 and 4 are cross-sectional views of the electronic apparatus 1, and illustration of portions other than the protrusions 3 a of the upper container 2 and the lower container 3 is omitted. The protrusion 3a supports a region outside the region (a portion indicated by cross-hatching in the metal substrate 4 in FIGS. 1 and 2) 4a on which the electronic component 5 of the metal substrate 4 is mounted from below. That is, the lower container 3 is a table on which the bag 6 and the metal substrate 4 are placed.

  To assemble each part 2, 3, 4, 6 of the electronic device 1, first, as shown in FIG. 1, the bag 6 enclosing the heat storage body 7 is inserted between the projections 3a on the inner side of the lower container 3. And place it on one side 3b. At this time, the heat storage body 7 may be in a completely solid state, or may be in a state of being heated and softened to some extent or in a liquid state. Until the electronic device 1 is used by the user, the heat storage body 7 is left in a completely solid state without being heated, thereby preventing deterioration of the heat storage body 7 and extending the life. . Moreover, by making the heat storage body 7 into a softened state or a liquid state, the bag 6 and the heat storage body 7 are given flexibility, and insertion between the protrusions 3a of the bag 6 and placement on the entire surface 3b are facilitated. It can be carried out.

  Next, as shown in FIG. 2, with the electronic component 5 facing away from the bag 6, the metal substrate 4 is placed on the upper surface of the protrusion 3a, and the bag 6 is pressed against the surface 3b and the side surface of the protrusion 3a with the metal substrate 4. Meanwhile, the bag 6 is brought into close contact with the metal substrate 4 over the mounting region 4a of the electronic component 5 of the metal substrate 4, and the protrusion 3a and the metal substrate 4 are fastened and fixed with the screws 8. Thus, when the projection 3a is formed of two parallel walls as shown in FIG. 3, the bag 6 and the heat storage body 7 in the bag 6 are not surrounded by the projection 3a (the projection 3a and the entire surface 3b). In a direction parallel to the metal substrate 4) and bite into the protrusion 3a. Further, when the protrusion 3a is composed of four or more cylinders as shown in FIG. 4, the bag 6 and the heat storage body 7 are not surrounded by the protrusion 3a in the lateral direction (the surface 3b between the protrusions 3a and the metal (In a direction parallel to the substrate 4) and bite into the protrusion 3a. At this time, the excessive spread of the bag 6 and the heat storage body 7 in the lateral direction is suppressed by the protrusion 3 a, and the bag 6 is securely attached to the metal substrate 4 over the mounting region 4 a of the electronic component 5 of the metal substrate 4.

  Then, as shown in FIG. 2, the edges of the upper container 2 are aligned with the edges of the lower container 3 and are connected by an adhesive or welding to assemble the containers 2 and 3. Thereafter, when the electronic component 5 operates and generates heat, the generated heat is transmitted to the heat storage body 7 through the metal substrate 4 and the bag 6, and the heat storage body 7 melts (phase change from solid to liquid). At this time, since the heat storage body 7 absorbs heat from the electronic component 5 and stores the heat, the electronic component 5 is prevented from becoming a high temperature that is equal to or higher than the operation upper limit temperature.

  If it carries out as mentioned above, the bag 6 which enclosed the thermal storage body 7 is inserted | pinched between the metal substrate 4 and the one surface 3b of the lower side container 3, and air | atmosphere is carried out to the metal substrate 4 over the mounting area | region 4a of the electronic component 5 of the metal substrate 4. It is possible to make close contact with less gaps. That is, the adhesion between the electronic component 5 and the heat storage body 7 through the metal substrate 4 and the bag 6 can be increased. For this reason, when the electronic component 5 operates and generates heat, the heat generated from the electronic component 5 is efficiently released to the heat storage body 7 through the metal substrate 4 and the bag 6, and the electronic component 5 exceeds the operation upper limit temperature. It becomes possible to suppress that it becomes high temperature.

  Further, by forming the protrusion 3a of the lower container 3 from two parallel walls as shown in FIG. 3, the bag 6 and the heat storage body 7 press the bag 6 against the entire surface 3b with the metal substrate 4. The projection 3a sometimes spreads in a direction perpendicular to the wall surface of the projection 3a, or shifts in a direction perpendicular to the wall surface of the projection 3a when the electronic device 1 is shaken or tilted. It can be surely prevented. Note that even if the bag 6 and the heat storage body 7 are sandwiched between the metal substrate 4 and the one surface 3b of the lower container 3 at a predetermined pressure, the bag 6 and the heat storage body 7 are arranged in the lateral direction parallel to the metal substrate 4 and the one surface 3b. Misalignment can be prevented to some extent. Also, as shown in FIG. 3, by making the side surfaces of both ends of the protrusion 3a curved, it is possible to prevent the bag 6 from coming into contact with both ends of the protrusion 3a and being damaged. Further, by forming the protrusion 3a from four or more columns as shown in FIG. 4, when the bag 6 and the heat storage body 7 press the bag 6 against the entire surface 3b with the metal substrate 4, the protrusion 3a The protrusion 3a reliably prevents the protrusion 3a from shifting in a direction perpendicular to the side surface or shifting in a direction perpendicular to the side surface of the protrusion 3a when the electronic device 1 is shaken or tilted. Can do. Moreover, as shown in FIG. 4, by making the side surface of the protrusion 3a into a curved surface, the bag 6 can be prevented from coming into contact with the side surface of the protrusion 3a and being damaged. For this reason, the bag 6 can be kept securely and stably adhered to the metal substrate 4 over the mounting region 4a of the electronic component 5 of the metal substrate 4.

  Moreover, since the bag 6 has elasticity, even if the volume changes due to the phase change between the solid and liquid of the heat storage body 7, the bag 6 expands and contracts following the change, and the bag 6 bursts. The escape of the heat storage body 7 from the bag 6 and the generation of bubbles in the bag 6 can be prevented. For this reason, it is possible to stably and efficiently release heat generated from the electronic component 5 to the heat accumulator 7 and to keep the electronic component 5 from becoming higher than the operation upper limit temperature.

  Further, since the containers 2 and 3 have thermal conductivity and heat dissipation, after the heat generated from the electronic component 5 is stored in the heat storage body 7, the heat storage body 7 dissipates the heat to the outside. All 7 can be prevented from melting. For this reason, it becomes possible to continue suppressing that the thermal storage body 7 and the electronic component 5 become high temperature.

  5 and 6 are longitudinal sectional views of an electronic apparatus 1 according to another embodiment of the present invention. In FIG. 5 and FIG. 6, the same reference numerals are given to the same parts and corresponding parts as those in FIGS. 1 to 4 for convenience. In the electronic device 1 of FIG. 5, a convex portion 3 c is provided at a location in contact with the center of the bag 6 on the inner surface 3 b of the lower container 3. Moreover, in the electronic device 1 of FIG. 6, the convex part 4c is provided in the location which contact | connects the center of the bag 6 on the opposite side to the electronic component 5 of the metal substrate 4. FIG. In order to assemble each part 2, 3, 4, 6 of these electronic devices 1, the bag 6 is placed on one surface 3b so that the convex portions 3c, 4c bite into the bag 6, and the metal substrate 4 is placed on the upper surface of the protrusion 3a. Put it on. Then, as described above, the bag 6 is pressed against the surface 3b and the side surface of the protrusion 3a with the metal substrate 4, and the bag 6 is brought into close contact with the metal substrate 4 over the mounting region 4a of the electronic component 5 of the metal substrate 4, thereby the protrusion 3a. And the metal substrate 4 are fixed with screws 8 and the containers 2 and 3 are connected and assembled.

  If it carries out as mentioned above, the bag 6 and the heat | energy storage body 7 which were closely_contact | adhered to the metal substrate 4 over the mounting area | region 4a of the electronic component 5 of the metal substrate 4 will shift | deviate to the horizontal direction parallel to the one surface 3b and the metal substrate 4. Can be reliably prevented by the convex portions 3c and 4c, and the close contact state between the metal substrate 4 and the bag 6 can be stably maintained. Further, when the heat storage body 7 is filled in the bag 6, when air is mixed in the bag 6 or the heat storage body 7 repeats a solid-liquid phase change in the bag 6, The contained air may appear and bubbles may be generated in the bag 6. However, as shown in FIG. 6, even if bubbles 9 are generated in the bag 6 by providing the convex portion 4 c at a location in contact with the center of the bag 6 of the metal substrate 4 disposed above the bag 6, By projecting the center of the bag 6 downward with the convex portion 4 c, the bubbles 9 in the bag 6 can be driven to a region outside the mounting region 4 a of the electronic component 5 on the metal substrate 4. For this reason, the air gap between the metal substrate 4 and the heat storage body 7 is further reduced, and the heat generated from the electronic component 5 is efficiently released to the heat storage body 7 to suppress the electronic component 5 from becoming high temperature. It becomes possible.

  The present invention can adopt various forms other than the embodiment described above. For example, in the above embodiment, the lower container 3 is used as a stand for supporting the bag 6 and the metal substrate 4, but the present invention is not limited to this example. A stand for supporting the metal substrate 4 may be provided separately from the container 3. In this case, the base is preferably formed of a metal material having heat conductivity and heat dissipation.

  In the embodiment shown in FIG. 4, an example in which the bag 6 is surrounded by the four columnar protrusions 3 a and the metal substrate 4 is supported has been described. However, the present invention is not limited to this example. In addition, for example, the metal substrate 4 may be supported by surrounding the bag 6 with two or more columnar protrusions having an elliptical, oval, or semicircular cross section.

It is a longitudinal cross-sectional view of the electronic device which concerns on embodiment of this invention. It is a longitudinal cross-sectional view of the electronic device which concerns on embodiment of this invention. It is a cross-sectional view of an electronic apparatus according to an embodiment of the present invention. It is a cross-sectional view of the electronic device which concerns on other embodiment of this invention. It is a longitudinal cross-sectional view of the electronic device which concerns on other embodiment of this invention. It is a longitudinal cross-sectional view of the electronic device which concerns on other embodiment of this invention.

Explanation of symbols

1 Electronic equipment 3 Lower container (table)
3a Projection 3b One surface 3c Convex part 4 Metal substrate 4a Region where metal part electronic component is mounted 4c Convex part 5 Electronic component 6 Bag 7 Heat storage body

Claims (5)

A metal substrate with electronic components,
An elastic bag enclosing a heat storage body;
A method of manufacturing an electronic device, comprising: a surface on which the bag is placed; and a base that protrudes from the surface and has a protrusion that supports the metal substrate so as to face the surface.
The bag is placed on the one surface of the table, the metal substrate is placed on the protrusion, and the bag is brought into close contact with the metal substrate over the region on which the electronic component is mounted while pressing the bag against the one surface with the metal substrate. And fixing the protrusion and the metal substrate. In the manufacturing method of the electronic device of Claim 1,
The protrusion is composed of two parallel walls that support a region outside the region on which the electronic component of the metal substrate is mounted,
Inserting the bag between the protrusions, placing the metal substrate on the protrusion, pressing the bag against the one surface of the base and the side surface of the protrusion with the metal substrate, over the region where the electronic component of the metal substrate is mounted A method of manufacturing an electronic device, wherein the protrusion and the metal substrate are fixed by closely contacting the metal substrate. In the manufacturing method of the electronic device of Claim 1,
The protrusion is composed of four or more pillars that support a region outside the region on which the electronic component of the metal substrate is mounted and whose side surfaces are formed in a curved shape,
Inserting the bag between the protrusions, placing the metal substrate on the protrusion, pressing the bag against the one surface of the base and the side surface of the protrusion with the metal substrate, over the region where the electronic component of the metal substrate is mounted A method of manufacturing an electronic device, wherein the protrusion and the metal substrate are fixed by closely contacting the metal substrate. In the manufacturing method of the electronic device of Claim 1,
Providing a convex portion at the one surface of the table or a position in contact with the bag of the metal substrate,
A method for manufacturing an electronic device, comprising: placing a bag on the one surface of the table and placing the metal substrate on the protrusion so that the convex portion bites into the bag. A metal substrate with electronic components,
An elastic bag enclosing a heat storage body;
The one surface on which the bag is placed, and a base having a plurality of protrusions that support the metal substrate so as to protrude from the one surface and face the one surface,
The metal substrate is fixed by being supported by the protrusions of the base in an area outside the area where the electronic component is mounted,
The bag is inserted between the protrusions and pressed against the one surface of the base and the side surfaces of the protrusions by the metal substrate, and is brought into close contact with the metal substrate over the region where the electronic component is mounted on the metal substrate. An electronic device characterized by

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