JP6491058B2 - Relay board and electronic device - Google Patents

Description

  The present invention relates to a relay substrate used for relaying electricity or heat in an electronic device such as a power module, and an electronic device including the relay substrate.

In recent years, electronic devices such as power modules or switching modules in which semiconductor elements such as IGBTs (Insulated Gate Bipolar Transistors) are mounted and a large current flows tend to be frequently used. In such an electronic device, for example, a heat radiating member such as a heat radiating fin or a water-cooled tube may be provided in order to improve the dissipating property of heat generated in the semiconductor element to the outside. In this case, in order to thermally connect the semiconductor element and the heat dissipating member and to ensure electrical insulation between the two, a relay substrate interposed between the two may be used.

  Such a relay substrate is generally plate-shaped, and one main surface thereof is connected to a semiconductor element, and the other main surface is connected to a heat dissipation member. In some cases, the semiconductor element is connected to the relay substrate while being mounted on a mounting substrate such as a metal plate. The semiconductor element (or the metal plate on which the semiconductor element is mounted) and the heat radiating member are joined to the relay substrate by, for example, grease, and are mechanically and thermally connected.

JP 2007-165620

  The conventional relay board has a problem that it is difficult to improve heat dissipation and reliability as an electronic device.

  That is, in the conventional relay board, the heat dissipation member is thermally connected to the relay board via grease or the like, and the thermal conductivity of grease is relatively small, so that the thermal conductivity from the relay board to the heat dissipation member is increased. Is difficult. For such a problem, for example, it is conceivable to thermally connect the heat dissipation member directly against the main surface of the relay substrate. However, even in this case, it is difficult to effectively improve the thermal connection (that is, heat dissipation) between the relay substrate and the heat dissipation member. This is because the relay substrate has a high rigidity and a relatively rough surface. That is, it is difficult to make the main surface of the relay substrate pressed against the heat radiating member in close contact with the surface of the relay substrate while appropriately deforming along the surface of the heat radiating member.

  Further, it is conceivable to connect the relay substrate and the heat radiating member using the active metal, but in this case, the following problems may occur. That is, due to the heat applied to melt the brazing material, stress is applied to the connecting portions due to the difference in thermal expansion coefficient between the relay substrate and the heat radiating member. Due to this stress, the relay substrate may be warped or cracked.

The relay substrate according to one aspect of the present invention is made of a ceramic material, and includes an insulating substrate having a first main surface, and a metal layer deposited on the first main surface of the insulating substrate. cage, wherein the first major surface of the insulating substrate, wherein with contains the same ceramic material as the ceramic material forming the insulating substrate, the is convex portion adhered to the insulating substrate is provided, wherein the convex portion is the The ceramic material is the same as the ceramic material forming the insulating substrate, and the crystal of the ceramic material is smaller than the insulating substrate in the convex portion .

  An electronic device according to an aspect of the present invention includes a relay board having the above-described configuration, a metal plate disposed on a second main surface opposite to the first main surface of the relay board, and the metal plate through the metal plate. An electronic component disposed on the second main surface of the relay substrate; and a heat radiator bonded to the first main surface of the relay substrate via the metal layer.

Since the relay substrate according to one aspect of the present invention has the above-described configuration, the insulating substrate and the metal layer are in direct contact with each other. Further, the convex portion attached to the first main surface of the insulating substrate bites into the metal layer deposited on the first main surface, and the strength of the mechanical connection of the metal layer to the first main surface of the insulating substrate is increased. It is improved than before. The insulating substrate can be pressed against the radiator via this metal layer, that is, bonded by pressure bonding. Since this metal layer is easily deformed as compared with the insulating substrate, it is easy to adhere to the surface of the radiator. Further, the convex portion is sintered and attached to an insulating substrate made of the same ceramic material. In addition, since the crystal size of the ceramic material of the particles that become the convex portion is small, the bonding of the convex portion to the insulating substrate becomes stronger, the anchor effect by the convex portion becomes more effective, and the metal layer adheres to the substrate The sex becomes higher.

  Therefore, the metal layer firmly bonded to the main surface of the insulating substrate is in close contact with the surface of the radiator, and the insulating substrate and the radiator are effectively thermally connected via the metal layer. Therefore, it is possible to provide a relay board that can easily manufacture a heat radiating member and an electronic module having a high heat radiating property from an electronic component such as a semiconductor element through the relay board and the metal layer.

  In addition, since the electronic module according to one aspect of the present invention includes the relay board having the above-described configuration, it is possible to provide an electronic module with high heat dissipation to the outside.

It is sectional drawing which shows the relay board | substrate and electronic device of embodiment of this invention. It is sectional drawing which expands and shows the A section of FIG.

  A relay board and an electronic device according to an embodiment of the present invention will be described with reference to the drawings. In addition, the distinction between the upper and lower sides in the following description is for convenience, and does not limit the upper and lower sides when the relay board and the electronic device are actually used.

  FIG. 1 is a cross-sectional view showing a relay board and an electronic device in a relay board according to an embodiment of the present invention, and FIG. 2 is an enlarged cross-sectional view showing a portion A of FIG.

  The relay substrate 10 according to the embodiment includes an insulating substrate 1 and a metal layer 2 provided on a first main surface 1a (for example, a lower surface) of the insulating substrate 1. Further, the radiator 3 is pressed against and joined to the lower surface of the insulating substrate 1 through the metal layer 2, and the metal plate 5 on which the electronic component 4 is mounted is opposite to the first main surface 1 a of the insulating substrate 1. The electronic device 20 is basically formed by being disposed on the second main surface 1b (for example, the upper surface). In the electronic device 20, the electronic component 4 is disposed on the second main surface 1 b via the metal plate 5.

  That is, in the electronic device 20, the metal plate 5 on which the electronic component 4 is mounted and the radiator 3 are mechanically connected via the relay substrate 10. In addition, the metal plate 5 and the relay substrate 10 are in close contact with each other, and the relay substrate 10 and the radiator 3 are in close contact with each other and are thermally connected to each other. Further, a heat transfer path from the metal plate 5 (electronic component 4) to the radiator 3 is formed.

  The insulating substrate 1 is a part for ensuring the mechanical strength as the relay substrate 10, that is, the strength for holding the metal plate 5 and the heat radiating body 3 in a state of being thermally connected to each other. Moreover, it is a part which forms a part of said heat-transfer path.

  The insulating substrate 1 is made of a ceramic material such as an aluminum oxide sintered body, a mullite sintered body, a silicon carbide sintered body, an aluminum nitride sintered body, or a silicon nitride sintered body. . In consideration of thermal conductivity (heat dissipation), a silicon nitride sintered body, an aluminum nitride sintered body, and a silicon carbide sintered body are more suitable for these ceramic materials. In view of mechanical strength, an aluminum oxide sintered body, a silicon nitride sintered body, and a silicon carbide sintered body are more suitable.

  If the insulating substrate 1 is made of, for example, silicon nitride ceramics, it is manufactured as follows. That is, first, an appropriate organic binder, plasticizer, solvent, and the like are added to and mixed with raw material powders such as silicon nitride, aluminum oxide, magnesium oxide, and yttrium oxide to prepare a ceramic slurry. Next, the ceramic slurry is formed into a sheet by a forming method such as a doctor blade method or a calender roll method to produce a band-shaped ceramic green sheet (ceramic green sheet). Next, the band-shaped ceramic green sheet is appropriately punched and formed into a predetermined shape, and a plurality of sheets are laminated as necessary to form a formed body. Then, the insulating substrate 1 can be manufactured by firing the molded body at a temperature of about 1600 to 2000 ° C. in a non-oxidizing atmosphere such as a nitriding atmosphere.

  The metal layer 2 is a portion for mechanically connecting the insulating substrate 1 and the heat radiating body 3 to each other with good thermal conductivity. Since the metal layer 2 that is more flexible and deformable than the insulating substrate 1 is attached to the first main surface 1a of the insulating substrate 1, when the heat dissipating member 3 is joined to the first main surface 1a, the heat dissipating body is formed. 3 is directly bonded to the metal layer 2. In other words, the insulating substrate 1 (relay substrate 10) and the heat radiating body 3 are bonded to each other via the metal layer 2.

  The metal layer 2 is deposited on the first main surface 1a of the insulating substrate 1 by a plating method such as an electroless plating method. In addition, the first main surface 1a of the insulating substrate 1 to which the metal layer 2 is deposited includes the same ceramic material as the ceramic material forming the insulating substrate 1, and the convex portion 1c attached to the insulating substrate 1. Is provided. The convex portion 1 c may be entirely made of the same ceramic material as that of the insulating substrate 1. Moreover, while containing the same ceramic material as the main component as the insulating substrate 1, you may contain the crystal | crystallization of a magnitude | size different from the crystal | crystallization of the ceramic material which forms the insulating substrate 1. FIG. The adhesion of the convex portion 1c to the insulating substrate 1 is due to the fact that the convex portion 1c and the insulating substrate 1 made of the same ceramic material are sintered at the interface portion of each other. Therefore, the convex portion 1 c is firmly bonded to the insulating substrate 1.

  Since the convex portion 1 c includes a ceramic material and is attached to the insulating substrate 1 by being sintered at the interface portion, the strength of bonding to the first main surface 1 a of the insulating substrate 1 is high. Further, the convex portion 1 c has the same mechanical strength and hardness as the insulating substrate 1. The metal layer 2 is deposited on the first main surface 1 a of the insulating substrate 1 provided with the convex portion 1 c, and the convex portion 1 c bites into the metal layer 2. Therefore, the strength of the mechanical connection of the metal layer 2 to the first main surface 1a of the insulating substrate 1 is improved as compared with the prior art.

  The heat sink 3 is bonded to the relay substrate 10 by, for example, pressing one exposed surface (main surface) of the heat sink 3 such as a block shape, which will be described later, against the first main surface 1a of the relay substrate 10 (insulating substrate 1). To be done. In this case, since the metal layer 2 is provided on the first main surface 1 a of the insulating substrate 1, the radiator 3 is actually pressed against the metal layer 2 and joined to the insulating substrate 1 via the metal layer 2. The At this time, the metal layer 2 is deformed according to the unevenness of the exposed surface of the heat radiating body 3 and is easily adhered. In other words, since the radiator 3 and the insulating substrate 1 of the relay substrate 10 are pressure-bonded to each other via the metal layer 2, mechanical connection between the radiator 3 and the relay substrate 10 is easier.

  That is, the insulating substrate 1 can be pressed against the radiator 3 through the metal layer 2 to be connected. Since the metal layer 2 is more easily deformed than the insulating substrate 1, the metal layer 2 is easily adhered to the surface of the radiator 3.

  Therefore, the metal layer 2 firmly bonded to the main surface of the insulating substrate 1 is in close contact with the surface of the radiator 3, and the insulating substrate 1 and the radiator 3 are effectively thermally connected via the metal layer 2. The Accordingly, it is possible to provide a relay substrate 10 that can easily manufacture a heat radiating member and an electronic module having a high heat radiating property from the electronic component 4 such as a semiconductor element through the relay substrate 10 and the metal layer 2. it can.

  When importance is attached to the adhesion of the heat radiating body 3 to the relay substrate 10, the metal layer 2 is attached to at least the entire region of the first main surface 1 a of the insulating substrate 1 where the heat radiating body 3 is joined. Further, the insulating substrate 1 may be attached to the entire surface of the first main surface 1a. Further, in consideration of economy and the like, the metal layer 2 may be partially attached to a region of the first main surface 1a of the insulating substrate 1 to which the radiator 3 is bonded. In this case, for example, the metal layer 2 may be applied in a range of about 40% or more of the region of the first main surface 1a of the insulating substrate 1 to which the radiator 3 is bonded. When the metal layer 2 is partially deposited on the first main surface 1a of the insulating substrate 1, the metal layer 2 may be deposited by, for example, electroless plating using a masking method.

  Here, “adhesiveness is good” means the following state. First, the metal layer 2 is formed along the unevenness of the insulating substrate 1, which means that a large contact area between the insulating substrate 1 and the metal layer 2 is effectively secured. Further, it means that the strength (adhesive strength) of mechanical connection between the insulating substrate 1 and the metal layer 2 is high due to the anchor effect that the metal layer 2 is formed along the unevenness of the insulating substrate 1.

  In order to provide the convex portion 1c on the first main surface 1a of the insulating substrate 1, for example, the following may be performed. That is, with respect to the ceramic green sheet to be the insulating substrate 1, fine particles of a ceramic material (unfired) containing the same components as the ceramic green sheet are attached to the exposed surface (surface to be the first main surface 1a). Are fired simultaneously. As a result, the fine particles become convex portions 1 c and are attached to the first main surface 1 a of the insulating substrate 1.

  In addition, when performing surface treatment such as blasting to remove foreign matters on the surface of the insulating substrate 1 after firing, it is relatively gentle to suppress the removal of the convex portions 1c. The surface treatment may be performed.

  In addition, when a plating method is used as a method for forming the metal layer 2, the following points are advantageous. That is, in the case of the plating method, the formation temperature of the metal layer 2 is close to room temperature, and the metal layer 2 (plating film) can be deposited directly on the first main surface 1 a of the insulating substrate 1. For this reason, it is difficult to make a gap between the insulating substrate 1 and the metal layer 2, and it is easy to increase the contact area between the two.

  Moreover, the metal material which forms the metal layer 2 is copper, nickel, cobalt, silver, gold | metal | money, palladium etc., for example. If the metal layer 2 is made of a metal material having a high thermal conductivity such as copper, it is advantageous in increasing the thermal conductivity between the relay substrate 10 and the radiator 3.

The metal layer 2 may be a thin film method without an adhesive metal layer or a metallization method without a bonding layer (low temperature sintering with nano metal particles, etc.) other than the plating method. In this case, the metal layer 2 is heated at a temperature of about 300 ° C.
Can be formed.

Note that the metal layer 2 may include an active metal material such as titanium. When the metal layer 2 contains an active metal material such as titanium, it is advantageous in terms of the strength of bonding of the metal layer 2 to the insulating substrate 1. However, titanium has a relatively low thermal conductivity (Ti thermal conductivity: 17 W
/ M / ° C.), which is disadvantageous in terms of the thermal conductivity between the relay substrate 10 and the radiator 3. Therefore, when the heat radiation is more important, the metal layer 2 is preferably made of copper or the like as described above and does not contain an active metal material such as titanium.

  That is, the metal layer 2 is, for example, from the viewpoint of heat dissipation in an electronic module, a metal material (such as copper or silver) formed directly on the first main surface 1a of the insulating substrate 1 by a plating method (not including an active metal material). Stuff). In this case, since the convex part 1c as described above is provided on the first main surface 1a, mechanical connection is directly made to the surface of the ceramic material (first main surface 1a of the insulating substrate 1) by plating. A high-strength metal layer 2 can be deposited.

  In addition to the thermal conductivity as described above, copper is selected as the metal material forming the metal layer 2 in consideration of the strength and economics of mechanical connection with the radiator 3. . In addition, when the metal layer 2 consists of copper, the following effects are also acquired. That is, in this case, the mechanical connection strength with the radiator 3 is such that copper forming the metal layer 2 and a metal material such as aluminum forming the radiator 3 (details will be described later) It is possible to further improve the strength of the mechanical connection with the heat dissipating body 3 by easy alloying. That is, the metal layer 2 can be more firmly connected to the heat radiating body 3 by alloying copper-aluminum.

  Moreover, if the insulating substrate 1 contains about 80% by mass or more of silicon nitride ceramic as a main component, it is advantageous in the following points. That is, in this case, the toughness as the insulating substrate 1 can be increased because the silicon nitride ceramic has high toughness as a physical property. Therefore, the possibility of mechanical destruction such as chipping of the insulating substrate 1 is more effectively reduced. The silicon nitride ceramic crystals are columnar (rod-like crystals), which are exposed on the first main surface 1 a of the insulating substrate 1. Therefore, it is possible to obtain an anchor effect due to the rod-like crystal entering the metal layer 2, which is advantageous in terms of the strength of deposition of the metal layer 2 on the insulating substrate 1.

  The radiator 3 is made of a metal material having a relatively high thermal conductivity such as aluminum as described above. The radiator 3 has a flat exposed surface that is pressed against and joined to the relay substrate 10 (actually, the metal layer 2 deposited on the first main surface 1a of the insulating substrate 1). That is, the radiator 3 includes, for example, a block-like portion having a main surface that is pressed against and joined to the relay substrate 10.

  Moreover, the heat radiator 3 may have a structure (not shown) such as a heat radiating fin for improving the heat radiating property with respect to the outside, on the opposite side to the main surface. Moreover, you may have a flow path for water cooling in said block-shaped part.

  The metal plate 5 on which the electronic component 4 is mounted is a flat plate member made of, for example, the same metal material as the heat dissipation member. The electronic component 4 is mounted on one main surface of the metal plate 5, and the other main surface is bonded to the relay substrate 10. In this case, the metal plate 5 is disposed on the second main surface 1b opposite to the first main surface 1a in the insulating substrate 1 of the relay substrate 10, and is joined to the second main surface 1b.

  The metal plate 5 functions as a member for mounting and fixing the electronic component 4. The metal plate 5 can also function as a part of a heat transfer path (so-called heat spreader or the like) for dissipating heat generated with the operation of the electronic component 4 to the outside.

An electronic component 4 is mounted on the metal plate 5. Specifically, the electronic component 4 is joined to the other main surface of the metal plate 5 by a connecting material (not shown) such as a low melting point brazing material. As the electronic component 4, an LSI (Large LSI) for a transistor, a CPU (Central Processing Unit)
A semiconductor element such as a scale integrated circuit (IGBT), an insulated gate bipolar transistor (IGBT), or a metal oxide semiconductor-field effect transistor (MOS-FET) can be used. The low melting point brazing material is, for example, solder such as tin-silver or tin-lead.

  As described above, the relay substrate 10 having the above configuration, the metal plate 5 disposed on the second main surface 1b opposite to the first main surface 1a of the relay substrate 10, and the relay substrate 10 via the metal plate 5 are provided. The electronic device 20 according to the embodiment is basically composed of the electronic component 4 arranged on the second main surface 1b of the heat sink and the radiator 3 bonded to the first main surface 1a of the relay substrate 10 via the metal layer 2. Is formed.

  According to such an electronic device 20, since the relay board 10 having the above configuration is included, it is possible to provide the electronic device 20 having high heat dissipation to the outside.

In the electronic device 20 of the embodiment, for example, as described above, the metal layer 2 and the heat radiating body 3 may be alloyed with each other at the interface portion. That is, an alloy layer of copper and aluminum may be formed at the interface portion between the metal layer 2 made of copper and the radiator 3 made of aluminum. In this case, in order to reduce the possibility that a brittle intermetallic compound inhibits heat conduction, the thickness of the metal layer 2 may be set to 0.2 to 1 μm so that the intermetallic compound layer does not become thick. Also, the metal layer 2 and the radiator 3 are first brought into close contact with each other in an inert atmosphere and heated, so that an alloy layer of the metal layer 2 and the radiator 3 is formed in advance, and a heat sink integrated with the relay substrate 10 is formed as an electron. You may make it use for the apparatus 20. FIG. In this case, it is possible to suppress the change with time of the connection portion between the metal layer 2 and the heat radiating body 3, thereby further stabilizing the heat dissipation characteristics of the electronic device 20.

  The electronic device 20 according to the embodiment may further include a lead 6, a bonding wire 7, a mold resin 8, and the like as in the example shown in FIG.

  The lead 6 is a strip-shaped metal material that is disposed so as to extend outward from the electronic component 4 in the horizontal direction outside the metal plate 5. The lead 6 functions as a terminal that forms a conductive path for electrically connecting the electronic component 4 to an external electric circuit. The end of the lead 6 may be directly connected to the metal plate 5. In other words, the lead 6 may include one integrated with the metal plate 5.

  In the electronic device 20 of the embodiment, the electronic component 4 is electrically connected to one end of the lead 6 that is closer to the electronic component 4 by the bonding wire 7. If the other end portion opposite to the one end portion of the lead 6 is electrically connected to the external electric circuit via a conductive connecting material such as solder, the electronic component 4 and the external electric circuit are electrically connected to each other. The

  The mold resin 8 is provided on the second main surface 1 b of the insulating substrate 1 so as to cover the metal plate 5 and the electronic component 4. The mold resin 8 is a member for protecting the electronic component 4 from the outside air, for example, and is formed of a resin material such as an epoxy resin.

  In the electronic device 20 of the embodiment, a metal layer (not shown) similar to the first main surface 1a may be deposited on the second main surface 1b of the insulating substrate 1 as well. In this case, if the second main surface 1b is also provided with a convex portion 1c similar to the first main surface 1a, the strength of the adhesion of the metal layer to the second main surface 1b is effectively increased. It can improve.

  In the relay substrate 10 and the electronic device 20 of the embodiment, the convex portion 1c is made of the same ceramic material as the ceramic material forming the insulating substrate 1, and the crystal of the ceramic material is the insulating substrate in the convex portion 1c. It may be smaller than 1.

  In this case, since the size of the crystal of the ceramic material of the particles that become the convex portions 1c is relatively small, if a liquid phase component such as a small amount of glass is present on the insulating substrate 1 during firing, the liquid phase component is the insulating substrate. It is easy to enter between the particles that become the convex portions 1c in contact with one body (upper surface). This makes it easier for the particles to sinter and adhere to the surface of the insulating substrate 1. Therefore, the bonding of the convex portion 1c to the insulating substrate 1 becomes stronger. In order to make the crystal of the ceramic material smaller in the convex portion 1 c than in the insulating substrate 1, for example, the purity of the ceramic main material of the convex portion 1 c may be higher than that of the insulating substrate 1. As a result, the particles of the convex portion 1c are difficult to sinter, the crystal growth rate in the convex portion 1c is slower than that of the insulating substrate 1, and the crystal of the ceramic material in the convex portion 1c becomes relatively small. The crystal size of the ceramic material is an arithmetic average of the sizes of a plurality of crystals at the time of observation using an electron microscope.

  For example, when both the insulating substrate 1 and the convex portion 1c are made of silicon nitride ceramics, the crystal size of the columnar crystal (particle) of silicon nitride is relatively small in the convex portion 1c. As a result, the grain boundary component of the crystal of the insulating substrate 1 enters and adheres to the silicon nitride particle interface of the convex portion 1 c, and the convex portion 1 c is firmly bonded to the insulating substrate 1. Therefore, the anchor effect by the convex part 1c becomes more effective, and the adhesiveness to the board | substrate of the metal layer 2 becomes higher.

  In the relay substrate 10 and the electronic device 20 according to the embodiment, the surface roughness of the convex portion 1 c may be smaller than the surface roughness of the first main surface 1 a of the insulating substrate 1.

  In this case, the following effects can be obtained because the surface roughness of the protrusions is small. That is, when the metal layer 2 is deposited on the first main surface 1a of the insulating substrate 1 including the convex portion 1c by plating, the metal layer on the surface of the convex portion 1c having a relatively small surface roughness and a smoother surface. The throwing power of 2 (plating film) is improved. Therefore, the metal layer 2 can be more easily deposited on the surface of the convex portion 1c, which is a relatively small surface to be plated.

  Therefore, in this case, it is possible to provide the relay substrate 10 and the electronic device 20 in which the uniformity of the plating film as the metal layer 2 with respect to the first main surface 1a of the insulating substrate 1 including the convex portion 1c is further improved. Can do. In addition, the surface roughness of the 1st main surface 1a of the insulated substrate 1 and the convex part 1c is arithmetic mean roughness, and can be measured by methods, such as atomic force microscopy.

  In the relay substrate 10 and the electronic device 20 according to the embodiment, the surface roughness of the convex portion 1c may be larger in the side surface portion than in the upper surface portion of the convex portion 1c. In the example of FIG. 2, since the convex portion 1c protrudes downward, the lower end surface of the convex portion 1c in FIG. 2 corresponds to the upper surface of the convex portion 1c.

  In this case, since the anchor effect of the side surface of the metal layer 2 and the convex part 1c increases, the adhesiveness of a board | substrate and the metal layer 2 improves more. That is, the anchor effect of the convex part 1c and the metal layer 2 is higher in the direction intersecting with the direction (vertical direction) in which the metal layer 2 is about to peel from the convex part 1c and the first main surface 1a of the insulating substrate 1. . Therefore, the anchor effect of the convex part 1c with respect to the metal layer 2 is higher, and it is more advantageous for improving the strength of the adhesion of the metal layer 2 to the insulating substrate 1.

  Moreover, since the surface roughness is comparatively small in the upper surface part of the convex part 1c, the throwing power of the plating film as the metal layer 2 with respect to the convex part 1c can also be ensured favorable.

In addition, the surface roughness of the convex portion 1c is smaller than the surface roughness of the first main surface 1a of the insulating substrate 1, and the surface roughness of the convex portion 1c is a side surface portion rather than the upper surface portion of the convex portion 1c. If the surface roughness is large, the surface roughness may be set so as to satisfy the relationship of the first main surface 1a> the side surface of the convex portion 1c> the upper surface of the convex portion 1c.

  Further, in the relay substrate 10 and the electronic device 20 of the embodiment, the height of the convex portion 1c is larger than the thickness of the metal layer 2, and the metal layer 2 is convex in the portion where the convex portion 1c is provided. It may be. The height of the convex portion 1c can be measured by a scale when the cross section of the relay substrate 10 including the convex portion 1c is observed with a metal microscope or an electron microscope.

  In this case, since the metal layer 2 includes a convex portion, the convex portion can provide an anchor effect of the metal layer 2 on the heat sink and an effect of improving heat dissipation. That is, when the radiator 3 (or the metal plate 5 if necessary) is connected to the surface of the metal layer 2 opposite to the relay substrate 10 by pressure bonding or the like, the protruding portion of the metal layer 2 is formed. By biting into the heat dissipating body 3, the adhesion is improved and the strength of mechanical joining is further improved. As a result, the metal layer 2 is effectively adhered to the material of the radiator 3 such as aluminum, and the thermal conductivity is increased.

In each of the above examples, the height of the convex portion 1c is, for example, about 16 to 90 μm, and the thickness of the metal layer 2 is, for example, about 0.1 to 20 μm. The height of the convex portion 1c is set to about 38 to 70 μm in consideration of a more effective anchor effect and ease of formation (that is, productivity as the relay substrate 10 and the electronic device 20). That's fine.

  Further, when the height of the convex portion 1c is larger than the thickness of the metal layer 2 and the metal layer 2 is convex in the portion where the convex portion 1c is provided, for example, the height of the convex portion 1c is about 38. The thickness of the metal layer 2 should just be set to about 0.2-1 micrometer, for example.

Further, the size (diameter) of the convex portion 1c in plan view is, for example, about 10 to 100 μm. The convex portion 1c improves the strength of deposition of the metal layer 2 on the insulating substrate 1 as long as the convex portion 1c is arranged at least in the portion of the first main surface 1a of the insulating substrate 1 where the metal layer 2 is deposited. The effect can be obtained without bias. In this case, the density of the projections 1c on the first main surface 1a may be such that, for example, about 1 to 15 projections 1c having the above-mentioned size are arranged per 1 mm ² as a unit area. . If 6 to 10 convex portions 1c are arranged per 1 mm ² , the unevenness of the deposition strength is further reduced. The size and arrangement density of the projections 1c in plan view can be known by observation using, for example, a scanning electron microscope.

  In addition, this invention is not limited to the said embodiment, A various change is possible if it is in the range of the summary of this invention. For example, the shape of the convex portion 1c in a longitudinal sectional view is a triangular shape (V-shaped or U-shaped) with a rounded tip (lower end) in the example of FIG. An elliptical arc shape, a quadrangular shape, etc. may be sufficient, the shape which combined these may be sufficient, and an indefinite shape may be sufficient. The shape of the convex portion 1c can be adjusted by, for example, the shape of the fine particles that become the convex portion 1c.

  Further, the convex portion 1c may have a shape (a shape having a so-called nail head-like portion) in which an upper surface portion (a lower tip portion in the example of FIG. 2) projects outward from the side surface. In this case, it is more effective in improving the anchor effect of the convex portion 1c with respect to the metal layer 2 and improving the heat transfer property by improving the adhesion between the metal layer 2 and the insulating substrate 1. The convex portion 1c having such a shape is, for example, a fine particle that becomes the convex portion 1c by appropriately adjusting the processing conditions (blast pressure, angle, etc.) such as jet scrub applied to the surface of the insulating substrate 1 after firing as described above. What is necessary is just to make it grind larger than the upper surface part.

DESCRIPTION OF SYMBOLS 1 ... Insulating substrate 1a ... 1st main surface 1a
1b... 2nd main surface 1c... Projection 2... Metal layer 3 ... Radiator 4 ... Electronic component 5 ... Metal plate 6 ... Lead 7 ... Bonding wire 8 ... Mold resin
10 ... Relay board
20 ... Electronic devices

Claims (6)

An insulating substrate made of a ceramic material and having a first main surface;
A metal layer deposited on the first main surface of the insulating substrate,
The first main surface of the insulating substrate includes a ceramic material that is the same as the ceramic material forming the insulating substrate, and is provided with a protrusion attached to the insulating substrate ,
The relay substrate , wherein the convex portion is made of the same ceramic material as the ceramic material forming the insulating substrate, and the crystal of the ceramic material is smaller than the insulating substrate in the convex portion . An insulating substrate made of a ceramic material and having a first main surface;
A metal layer deposited on the first main surface of the insulating substrate,
The first main surface of the insulating substrate includes a ceramic material that is the same as the ceramic material forming the insulating substrate, and is provided with a protrusion attached to the insulating substrate,
The relay substrate, wherein the surface roughness of the convex portion is smaller than the surface roughness of the first main surface of the insulating substrate. Relay substrate according to claim 1, wherein the surface roughness of the convex portion, characterized in that less than the surface roughness of the first main surface of the insulating substrate. The relay substrate according to claim 2 or 3 , wherein a surface roughness of the convex portion is larger in a side surface portion than an upper surface portion of the convex portion. The height of the said convex part is larger than the thickness of the said metal layer, The said metal layer is convex in the part in which the said convex part was provided, The any one of Claims 1-4 characterized by the above-mentioned. Relay board described in 1. The relay substrate according to any one of claims 1 to 5 ,
A metal plate disposed on a second main surface opposite to the first main surface of the relay substrate;
An electronic component disposed on the second main surface of the relay board via the metal plate;
An electronic device comprising: a heat radiator joined to the first main surface of the relay substrate via the metal layer.

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