JP2007227489A - Heat dissipation substrate, its production method and light emitting module employing it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat dissipation substrate for electronic component such as an LED requiring heat dissipation in which high heat dissipation properties of a ceramic member are utilized without requiring substantially no machining of the ceramic member itself and excellent machinability is ensured. <P>SOLUTION: When an electronic component such as a light emitting element 106 requiring heat dissipation is mounted on a ceramic wiring board 108 formed on a metal plate 104, heat emitted from the light emitting element 106 can be dissipated to the metal plate 104 excellent in machinability and thermal conductivity through the ceramic wiring board 108. Furthermore, the heat reaching a lead frame 100 excellent in machinability and thermal conductivity connected with the ceramic wiring board 108 can be dissipated to the metal plate 104 through a heat conductive resin 102 thence to an external circuit (not shown), and thereby machinability and heat dissipation properties of the heat dissipation substrate can be enhanced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention requires the use of circuit boards such as power circuit modules that require high heat dissipation for plasma TV and mobile phone base stations, and heat dissipation used in backlights for liquid crystal televisions and headlights for automobiles. The present invention relates to a heat dissipation substrate used for the use of a light emitting module, a manufacturing method thereof, and a light emitting module using the same.

  Conventionally, a ceramic substrate is used as this type of heat dissipation substrate. Therefore, as a conventional heat dissipation substrate, a light emitting module using LEDs will be described as an example.

  Conventionally, a cold cathode tube or the like has been used for a backlight of a liquid crystal television or the like, but in recent years, it has been proposed to mount a semiconductor light emitting element such as an LED or a laser on a heat dissipating substrate ( For example, see Patent Document 1).

  FIG. 9 is a cross-sectional view showing an example of a conventional light emitting module. In FIG. 9, the light emitting element 2 is mounted in the recess formed in the ceramic substrate 1. The plurality of ceramic substrates 1 are fixed on the heat sink 3. Further, the plurality of ceramic substrates 1 are electrically connected by a connection substrate 5 having a window portion 4. The light 6 emitted from the LED is emitted to the outside through the window portion 4 formed on the connection substrate 5. In FIG. 9, the wiring in the ceramic substrate 1 having the recesses and the connection substrate 5, the LED wiring, and the like are not shown. Such light emitting modules are used as backlights for liquid crystals and the like.

  However, the light emitting element 2 such as an LED is influenced by the light emission efficiency and the light emission color depending on the heat generation temperature. Therefore, although cooling of the light emitting element 2 is important, the ceramic substrate 1 is difficult and expensive to process into various shapes even if the heat dissipation is high, so a heat dissipation substrate that is cheaper and excellent in workability is required. It was.

In addition, although the light emitting module was taken as an example here, it is needless to say that the same applies to a plasma television or a substrate that requires various types of heat radiation for vehicle mounting.
JP 2004-311791 A

  However, in the conventional configuration, it is necessary to use various shapes of ceramic members according to the application, but it is necessary to process the ceramic material into a complicated shape, and there is a problem that the cost is easily increased. It was.

  The present invention solves the above-mentioned conventional problems, and provides a high heat dissipation substrate excellent in workability, which hardly uses the ceramic member itself while utilizing the high heat dissipation property of the ceramic member. Objective.

  In order to solve the conventional problems, the present invention provides a ceramic wiring board having wiring formed on at least one surface, a metal plate for fixing the ceramic wiring board, wiring on the ceramic wiring board, and electrically A plurality of connected lead frames are used as a heat dissipation board fixed by a heat transfer resin made of a ceramic filler and a thermosetting resin.

  The heat dissipating board of the present invention, the manufacturing method thereof, and the light emitting module using the heat dissipating board can eliminate the need for complicated processing of the ceramic material by using the ceramic wiring board only in a portion where high heat dissipation is required.

  In other words, in the heat dissipation board of the present invention, only components that require high heat dissipation are selectively mounted on a ceramic wiring board that is expensive but has excellent thermal conductivity. By fixing on an excellent metal plate, the heat transferred to the ceramic wiring board can be efficiently dissipated. Further, only the minimum necessary wiring is left on the ceramic wiring board, and the wiring occupying the remaining area is made into a lead frame that is easy to process and excellent in thermal conductivity. Then, the lead frame is insulated from the metal plate using a heat transfer resin and used as a part of the wiring of the heat dissipation substrate, whereby the ceramic substrate can be reduced in size and cost.

  As described above, in the case of the high heat dissipation substrate of the present invention, the lead frame and the metal plate are formed into a predetermined shape even for the use that cannot be dealt with in terms of size, shape, and cost with the conventional ceramic-based heat dissipation substrate. This can be done by taking advantage of the features of processing and fixing with heat transfer resin.

(Embodiment 1)
Hereinafter, the heat radiating substrate according to Embodiment 1 of the present invention will be described using a light emitting module as an example. As the light emitting module, for example, a light emitting element such as an LED or a semiconductor laser is mounted. However, instead of the light emitting element, for a transformer, a semiconductor, a transistor, a sensor component, etc. where heat generation is a problem. Needless to say, it can be used as a plasma television or a heat dissipation substrate for vehicles.

  1A and 1B are a perspective view and a cross-sectional view of a heat dissipation board in Embodiment 1, and will be described for a case where a light emitting element is mounted on a heat dissipation component.

  1A is a perspective view of the heat dissipation board, and FIGS. 1B and 1C are cross-sectional views of the heat dissipation board. In FIG. 1, 100 is a lead frame, 102 is a heat transfer resin, 104 is a metal plate, 106 is a light emitting element, 108 is a ceramic wiring board, and 110 is an arrow.

  In FIG. 1A, a light-emitting element 106 is, for example, an LED or a semiconductor laser in which heat generation is a problem. It is desirable to mount the light emitting elements 106 on the ceramic wiring substrate 108 with high density. By mounting the light emitting elements 106 at a high density, it is possible to facilitate color mixing (or white balance by mixing colors) when a plurality of light emitting elements 106 emit light with different light emission colors, and the temperature variation between each other is also small. it can. Further, the product cost can be reduced by downsizing the ceramic wiring substrate 108.

  In FIG. 1, neither wiring nor insulating layer (or protective layer) formed on the ceramic wiring substrate 108 is shown. As shown in FIG. 1A, the plurality of lead frames 100 are embedded in the heat transfer resin 102 (only the surface of the lead frame 100 is exposed). By embedding the lead frame 100 in the heat transfer resin 102 in this manner, the adhesive strength between the lead frame 100 and the heat transfer resin 102 can be increased, and the thermal conductivity from the lead frame 100 to the heat transfer resin 102 can be increased. Then, one end of the lead frame 100 is electrically connected to a wiring (not shown) formed on the ceramic wiring substrate 108. Then, the remaining end of the lead frame 100 protrudes from the heat transfer resin 102 to the outside, and this portion is taken out as an electrode (external electrode or electrode terminal for attachment). Thus, it corresponds to a large current of several amperes to several tens of amperes. Further, the lead frame 100 can be bent in accordance with the mounting form, and the strength required for the heat generating substrate can be secured even in the bent state. Further, the heat of the ceramic wiring board 108 can be conducted to the outside through the lead frame 100.

  In FIG. 1A, the lead frame 100 is insulated from the metal plate 104 by the heat transfer resin 102. In FIG. 1A, the heat transfer resin 102 surrounds the ceramic wiring board 108 as if it were a frame, but it is not necessary to stick to this shape.

  Next, description will be made with reference to FIGS. 1B and 1C. FIG. 1B and FIG. 1C are cross-sectional views of the heat dissipation component shown in FIG. As shown in FIGS. 1B and 1C, the ceramic wiring substrate 108 is fixed on the metal plate 104. The ceramic wiring board 108 is desirably fixed on the metal plate 104 over the entire area. In this way, as the area for fixing the ceramic wiring board 108 and the metal plate 104 is increased, the heat of the ceramic wiring board 108 can be effectively released to the metal plate 104. Here, it is desirable to make the metal plate 104 larger than the ceramic wiring substrate 108. By making the metal plate 104 larger than the ceramic wiring substrate 108, the contact (or fixing) area between the ceramic wiring substrate 108 and the metal plate 104 can be maximized.

  As shown in FIGS. 1B and 1C, the lead frame 100 is insulated from the metal plate 104 by the heat transfer resin 102. Here, as the heat transfer resin 102, as described in detail later, it is desirable to use a material having high thermal conductivity formed by adding a ceramic filler to a thermosetting resin. By adding a ceramic filler to the heat transfer resin 102 and increasing its thermal conductivity, the heat transferred from the ceramic wiring board 108 to the lead frame 100 is transferred to the metal plate 104 via the heat transfer resin 102.

  Note that it is desirable that the light-emitting element 106 whose heat generation is a problem be mounted on the surface of the ceramic wiring substrate 108. This is because, as shown in FIGS. 1B and 1C, the ceramic wiring board 108 is fixed on the metal plate 104, so that the heat dissipation characteristics of the ceramic wiring board 108 are excellent. Then, the light emitting element 106 which is a heat generating component is mounted on the ceramic wiring substrate 108. When the light emitting element 106 is resin-sealed, a mounting method using a wire bonder, a flip chip, a bump, or the like can be selected. By selectively mounting the light emitting element 106 on which heat generation is a problem on the ceramic wiring substrate 108 in this way, the heat balance between the light emitting elements 106 can be kept uniform, so that the light emission balance within the entire light emitting module is achieved. It becomes easy to take.

  In FIG. 1C, the lead frame 100 is embedded in the heat transfer resin 102 and at the same time, a predetermined inclination is formed on the side of the heat transfer resin 102 facing the light emitting element 106. In FIG. 1C, an arrow 110 indicates a state in which light emitted from the light emitting element 106 is reflected forward using the heat transfer resin 102 as a reflective surface (or reflector).

  Next, the heat dissipation mechanism of the heat dissipation substrate of the present invention will be described with reference to FIG. 2A and 2B are a plan view and a cross-sectional view illustrating a heat dissipation mechanism of the heat dissipation substrate. Here, the light emitting element 106 will be described as an example of the heat generating component.

  FIG. 2A is a plan view illustrating a heat dissipation mechanism in the planar direction. In FIG. 2A, heat generated from the light emitting element 106 is transmitted to the ceramic wiring substrate 108 on which the light emitting element 106 is mounted as indicated by an arrow 110a. Then, the heat transmitted to the ceramic wiring substrate 108 is transmitted to the lead frame 100. The heat transferred to the lead frame 100 is transferred to the heat transfer resin 102 in which the lead frame 100 is embedded. This heat is transferred to an external circuit (not shown) connected to the lead frame 100.

  FIG. 2B is a cross-sectional view illustrating a heat dissipation mechanism in the thickness direction. In FIG. 2B, an arrow 110b means light generated from the light-emitting element 106. The light emitting element 106 emits light as indicated by an arrow 110b, and heat generated in the light emitting element 106 is transmitted to the ceramic wiring substrate 108 as indicated by an arrow 110c. The heat transmitted to the ceramic wiring substrate 108 is transmitted to the metal plate 104 that fixes the ceramic wiring substrate 108. Then, if necessary, the heat is transmitted from the metal plate 104 to a heat radiating plate (for example, a heat radiating plate not provided with a heat radiating element such as a fin). In this way, the light emitting element 106 can be effectively cooled. The heat transmitted to the lead frame 100 is transmitted to the metal plate 104 through the heat transfer resin 102. Thus, the heat generated in the light emitting element 106 can be radiated in all directions (or to the metal plate 104) through the ceramic wiring board 108 having excellent heat dissipation.

  It is desirable to make the area of the metal plate 104 larger than the area of the ceramic wiring board 108. By making the area of the metal plate 104 larger than the area of the ceramic wiring substrate 108, the bonding area between the ceramic wiring substrate 108 and the metal plate 104 can be maximized, so that the maximum heat dissipation effect can be obtained at the minimum cost.

  The ceramic wiring board 108 and the metal plate 104 are joined by a metal member, a resin material, a glass material or the like having a high thermal conductivity, so that the thermal conductivity from the ceramic wiring board 108 to the metal plate 104 can be increased. . Here, it is desirable to form wiring on one surface or more of the ceramic wiring substrate 108. Then, the light emitting element 106 and the lead frame 100 are mounted on one side of the ceramic wiring substrate 108, and wiring (for example, a solid pattern) formed on the remaining one side (side facing the metal plate 104) is formed. The metal plate 104 and the ceramic wiring board 108 can be joined using this wiring. For example, the metal plate 104 can be joined with solder, silver solder, or a metal member that is sintered or melted at 200 ° C. or more and less than 900 ° C. By previously forming the wiring on the metal plate 104 side of the ceramic wiring board 108 in this way, the wettability of such a metal member to the ceramic wiring board 108 can be enhanced. As the surface treatment of the ceramic wiring substrate 108, in addition to the fired thick film wiring material, an organic metal (a metal organic compound, which can be heat-treated to form a metal thin film), or a thin film (sputtering, etc.) can also be used. it can. By performing the surface treatment of the ceramic wiring substrate 108 in this way (wiring formation is one of them), it is also possible to apply solder or silver brazing or metal members that are sintered or melted at 200 ° C. to 900 ° C. Increase wettability. A commercially available metal member can be selected as such a metal member, and a flux treatment (or a flux material) can be used as necessary. Further, by subjecting the metal plate 104 to surface treatment or plating (for example, metal vapor deposition or tin plating by sputtering or the like), the metal plate 104 has a high thermal conductivity like copper but is easily oxidized. The wettability can also be improved. Here, the bonding of the ceramic wiring board 108 and the metal plate 104 with the metal member is preferably performed with a high thermal conductivity of the metal member. If necessary, glass materials and resin materials can be used. In this case, a material having as high a thermal conductivity as possible (or a metal-based or ceramic-based material or a filler having excellent heat conductivity such as graphite should be added. ) Is desirable. The member that joins between the metal plate 104 and the ceramic wiring board 108 does not need to be an insulator. This is because the ceramic wiring board 108 is an insulator. When a metal member is used as a member to be joined, if the melting point or melting temperature is less than 200 ° C., the light emitting element 106 may be remelted when the light emitting element 106 is soldered to the ceramic wiring substrate 108 or the lead frame 100 There is. When the temperature is higher than 900 ° C., it is necessary to select a more expensive member in order to prevent oxidation of the metal plate 104.

  Next, the ceramic wiring board 108 will be described with reference to FIGS. FIG. 3 is a circuit diagram for causing a plurality of light emitting elements such as LEDs to emit light. 3A is a circuit diagram for driving a plurality of light emitting elements individually, and FIG. 3B is a circuit diagram for driving a plurality of light emitting elements simultaneously (in parallel). 3A and 3B, reference numeral 112 denotes a resistor, which is inserted in series with the light-emitting element 106. When the light emitting element 106 is driven in this way, it is desirable to insert the resistor 112 in series with the light emitting element 106. By inserting the resistor 112 in series, the voltage applied to each light emitting element 106 can be kept below the maximum rating of the light emitting element 106. As the resistor 112, a resistor or a resistor element (for example, a fired thick film resistor using a chip resistor or ruthenium oxide) can be used. The protective resistor 112 depends on the characteristics of the light-emitting element 106. For example, in the case of about 3 to 4 V, about several Ω to about 1 KΩ is appropriate. By inserting the resistor 112 in this manner, light emission can be stabilized and the life of the light emitting element 106 can be increased. 3B, when a plurality of light-emitting elements 106 are connected in parallel, variation in current (or light emission) flowing through the light-emitting elements 106 can be suppressed by inserting the resistor 112. Needless to say, if the resistor 112 is a device that stabilizes the light emission of the light-emitting element 106, another protective element (thermistor, semiconductor, Zener diode, or the like) can be used as the resistor 112.

  Next, the case where the resistor 112 is formed on the ceramic wiring substrate 108 will be described with reference to FIG. FIG. 4 is a perspective view and a top view for explaining the ceramic wiring board. FIG. 4A is a perspective view of the ceramic wiring board, and corresponds to a state in which the heat transfer resin 102 is removed from FIG. In FIG. 4A, the ceramic wiring board 108 is fixed to the metal plate 104 over the entire surface. This is to increase heat conduction from the ceramic wiring board 108 to the metal plate 104. A plurality of light emitting elements 106 are mounted on the ceramic wiring board 108, and this is intended to enhance the heat dissipation effect by mounting the light emitting elements 106 on which heat generation is a problem on the ceramic wiring board 108. It is what. Further, by connecting a part of the lead frame 100 to the ceramic wiring substrate 108, a part of the necessary wiring can be replaced with the lead frame 100, and the ceramic wiring substrate 108 is reduced in size and cost. In addition, since the ratio of forming the wiring 120 on the ceramic wiring substrate 108 is reduced, the amount of expensive members such as silver palladium can be reduced. In FIG. 4A, the wiring on the surface of the ceramic wiring board 108 is not shown.

  FIG. 4B is a top view of the ceramic wiring board. In FIG. 4B, 114 is an overcoat, 116 is a window, 118 is a dotted line, and 120 is a wiring. Here, the overcoat 114 is an insulator such as resin or glass, and protects the wiring 120 formed on the ceramic wiring substrate 108. Further, the wiring 120 can be exposed to the outside through the window 116 formed in the overcoat 114. The light emitting element 106 can be mounted on the wiring 120 exposed in the window 116. As the wiring 120, a wiring member such as silver, silver palladium, or copper can be used.

  In FIG. 4B, a dotted line 118a indicates the mounting position of the lead frame, and the lead frame 100 (not shown) is mounted on the window 116 formed in the overcoat 114 as indicated by the dotted line 118a. . A dotted line 118b indicates a mounting position of the light emitting element 106, and the light emitting element 106 (not shown) is mounted on the window 116 formed in the overcoat 114 as indicated by the dotted line 118b. Note that the light-emitting element 106 and the lead frame 100 can be easily mounted by using the overcoat 114 as a kind of solder resist, but the overcoat 114 is not essential. For example, after the light-emitting element 106 is mounted on a bare chip, a transparent sealing resin (a material having elasticity such as silicon rubber is desirable. In the case of a hard resin, a wiring wire or the like can be disconnected due to a thermal expansion coefficient of the light-emitting element 106. The light emitting element 106 can be filled using a protective material. In such a case, the overcoat 114 can be omitted as necessary. Further, by selecting a white member having high light reflectance as the overcoat 114, light generated from the light emitting element 106 can be efficiently reflected forward, and the reflection efficiency can be increased.

  In FIG. 4B, the resistor 112 is formed on the ceramic wiring substrate 108 and protected by the overcoat 114. Here, as the resistor 112, a fired type thick film type using ruthenium oxide or the like can be used. By using the thick film type, one having a small TCR (temperature characteristic of resistance value) (for example, 200 ppm / ° C. or less) can be selected. By selecting one having a small TCR, even when the temperature of the ceramic wiring substrate 108 rises due to heat generation of the light emitting element 106, the influence of the resistance value can be reduced. As the resistor 112, a commercially available square chip resistor may be mounted on the ceramic wiring substrate 108 by soldering. Further, as shown in FIG. 4B, a resistor 112 may be formed on the surface of the ceramic wiring substrate 108 by using a method such as printing and baking or a thin film as in an HIC (hybrid integrated circuit). In this way, by forming the resistor 112 directly on the ceramic wiring substrate 108, when using a square chip resistor (in the case of a square chip resistor, the 1125 to 1 / 4W for the 20125 type and its dimensions are watts. The number of watts can be apparently increased compared to the case where the number is determined. As a result, since the TCR of the resistor can be substantially kept small, driving of the light emitting element 106 can be stabilized.

Next, the structure of the ceramic wiring board will be described with reference to FIG. FIG. 5 is a cross-sectional view showing the structure of the ceramic wiring board. In FIG. 5, reference numeral 122 denotes a ceramic plate, for example, an alumina substrate (Al ₂ O ₃ substrate) or an aluminum nitride substrate (AlN substrate). Such a substrate is inexpensive, using a green sheet method, a casting method, an extrusion method, or the like in a thickness range of about 0.1 mm to about 1 mm (a thickness in the range of about 0.2 mm to 0.65 mm is easy to use). It is commercially available. Also, a resistor 112, a wiring 120, an overcoat 114, and the like to be formed on such a substrate are commercially available.

  In FIG. 5, wiring 120 is formed on the ceramic plate 122, and a resistor 112 is formed between some of the plurality of wirings 120. The wiring 120 is formed of a commercially available member mainly composed of silver or copper by using a technique such as printing, thin film, or plating. An overcoat 114 can be formed on the wiring 120 and the resistor 112. Then, by exposing the wiring 120 inside the window 116 formed in the overcoat 114, the lead frame 100 and the light emitting element 106 can be mounted as indicated by the arrow 110 in FIG. For these mountings, physical connection methods such as solder mounting, welding, and bumps can be used. In this case, the overcoat 114 can also be expected to have an effect as a solder resist. Further, since the lead frame 100 and the light emitting element 106 can be formed on the overcoat 114 by protecting the wiring 120 with the overcoat 114, a kind of bridge (or jumper or multilayer wiring) is formed. The degree of freedom is also increased.

  Next, an example of the manufacturing method of the heat sink of the present invention will be described with reference to FIG. FIG. 6 is a cross-sectional view illustrating a method for manufacturing a heat dissipation board. In FIG. 6, reference numeral 124 denotes a plate material. First, as shown in FIG. 6, a commercially available plate material 124 is prepared. The plate member 124 may be a coil wound in a coil shape for easy handling as shown in FIG. Next, using a mold or the like (not shown), the plate material 124 is punched into a predetermined shape as shown in FIG. Next, as shown in FIG. 6C, between the lead frame 100 and the metal plate 104, a ceramic wiring board 108 (in which wiring 120 or the like is formed in advance as shown in FIG. 5), transmission, and the like. The thermal resin 102 is set. It is desirable that the heat transfer resin 102 be preliminarily molded into a sheet shape (or plate shape, bowl shape, donut shape) or the like in advance. In this way, by pre-molding the heat transfer resin 102 into a plate shape, a bowl shape, or the like, it is possible to prevent air residue from being generated at the interface with the metal plate 104 or the lead frame 100 during pressing. The heat dissipation effect can be enhanced.

  As indicated by an arrow 110, the metal plate 104, the ceramic wiring substrate 108, and the lead frame 100 are fixed with the heat transfer resin 102 using a press or a mold (both not shown). At this time, by heating a press or a mold (both not shown), the heat transfer resin 102 can be softened, and the adhesion to the metal plate 104 and the lead frame 100 can be enhanced. The resin 102 is thermally cured. Thus, as shown in FIG. 6D, a heat dissipation substrate integrated with the heat transfer resin 102 is manufactured.

  In FIG. 6C, the ceramic wiring board 108 may be fixed to the surface of the metal plate 104 in advance. In this case, for example, the wiring 120 is formed with a thick film or a thin film on the back surface side (the side in contact with the metal plate 104) of the ceramic wiring substrate 108, and the wiring 120 and the metal plate 104 are made of a low melting point metal such as solder or tin. By fixing, heat conduction from the ceramic wiring board 108 to the metal plate 104 can be enhanced.

  FIG. 7 is a perspective view showing a state in which a metal plate, a ceramic wiring board, a lead frame, and the like are fixed with heat transfer resin, and corresponds to the perspective view of FIG. In FIG. 7, on a metal plate 104, a ceramic wiring board 108, a heat transfer resin 102, a lead frame 100, and the like on which a predetermined pattern is formed are set. Then, the members are firmly integrated by heating and pressing as shown by an arrow 110 (a heating press apparatus is not shown). The ceramic wiring board 108 may be fixed on the metal plate 104 in advance by using silver solder, solder, tin or the like as a kind of adhesive layer. Alternatively, the lead frame 100 may be fixed on the ceramic wiring substrate 108, and in this state, the lead frame 100 may be fixed to the metal plate 104 with the heat transfer resin 102 as shown in FIG. Thus, as shown in FIG. 8, a heat dissipation board in which the lead frame 100 is embedded in the heat transfer resin 102 can be manufactured.

  FIG. 8 is a perspective view for explaining a state in which components are mounted on a completed heat dissipation board. In FIG. 8, a ceramic wiring substrate 108 is fixed on the metal plate 104. On the metal plate 104, one end of the lead frame 100 is connected to the wiring 120 (not shown) of the ceramic wiring substrate 108 with the lead frame 100 embedded in the heat transfer resin 102. In FIG. 8, an arrow 110 indicates a state in which electronic components are mounted. For example, a plurality of light emitting elements 106 are mounted on the surface of the ceramic wiring substrate 108. After mounting the light emitting element 106 on the surface of the ceramic wiring substrate 108 in this way, the light emitting element 106 can be protected by covering (or sealing) the light emitting element 106 with a transparent protective resin (not shown). Further, when the light-emitting element 106 is sealed with this resin, the heat transfer resin 102 can also serve as a kind of dam (or a bank on which the protective resin does not spill), so that workability can be improved.

As the heat transfer resin 102, it is desirable to use a resin in which a highly heat-dissipating inorganic filler is dispersed in a curable resin. The inorganic filler has a substantially spherical shape, and its diameter is suitably from 0.1 to 100 microns (if it is less than 0.1 microns, it may be difficult to disperse in the resin, and if it exceeds 100 microns) This increases the thickness of the heat transfer resin 102 and affects the thermal diffusivity). Therefore, the filling amount of the inorganic filler in the heat transfer resin 102 is filled at a high concentration of 70 to 95% by weight in order to increase the thermal conductivity. In particular, in the present embodiment, the inorganic filler is a mixture of two types of Al ₂ O ₃ having an average particle size of 3 microns and an average particle size of 12 microns. By using the Al ₂ O ₃ of the large and small two types of particle size, it is possible to fill the Al ₂ O ₃ of small particle size in the gap Al ₂ O ₃ of large particle size, Al ₂ O ₃ 90 wt% near Can be filled to a high concentration. As a result, the heat conductivity of the heat transfer resin 102 is about 5 W / (m · K).

In addition, when the filling rate of a filler is less than 70 weight%, thermal conductivity may fall. Further, if the filling rate (or content rate) of the filler exceeds 95% by weight, the moldability of the uncured heat transfer resin 102 may be affected. Or if it is attached to the surface). The inorganic filler may include at least one selected from the group consisting of MgO, BN, SiO ₂ , SiC, Si ₃ N ₄ , and AlN instead of Al ₂ O ₃ .

If MgO is used, the linear thermal expansion coefficient can be increased. Further, when SiO ₂ is used, the dielectric constant can be reduced, and when BN is used, the linear thermal expansion coefficient can be reduced. Thus, the heat transfer resin 102 having a thermal conductivity of 1 W / (m · K) or more and 20 W / (m · K) or less can be formed. In addition, when heat conductivity is less than 1 W / (m * K), it influences the heat dissipation of a light emitting module. Moreover, when it is going to make thermal conductivity higher than 20 W / (m * K), it is necessary to increase the amount of fillers and may affect the workability at the time of a press.

  Note that if the thickness of the insulator made of the heat transfer resin 102 is reduced, the heat generated in the light emitting element 106 attached to the lead frame 100 can be easily transferred to the metal plate 104. Since the thermal resistance increases, the optimum thickness may be set in consideration of the withstand voltage and the thermal resistance.

  The thermosetting insulating resin desirably contains at least one kind of resin among epoxy resin, phenol resin and cyanate resin. Specifically, it is desirable to include at least one selected from the group consisting of epoxy resins, phenol resins, and isocyanate resins. These resins are excellent in heat resistance and electrical insulation. If the thickness of the heat transfer resin 102 is reduced, the heat generated in the light emitting element 106 attached to the lead frame 100 can be easily transferred to the metal plate 104. However, if the thickness is too thick, the heat resistance increases. Therefore, the optimum thickness may be set to 50 microns or more and 500 microns or less in consideration of the withstand voltage and the thermal resistance.

  Thus, a filler with good thermal conductivity can be used as the heat transfer resin 102. In addition, by selecting a material with excellent light reflectivity as the filler, in the case of an optical component such as a light emitting module, the thermal conductivity and light reflectivity (or the formation of white light by mixing different monochromatic lights) are simultaneously enhanced. It is done. In the case of a plasma TV or a vehicle-mounted device, it is desirable to use a color having a high emissivity of infrared rays (or far infrared rays) such as black.

  Next, the material of the lead frame 100 will be described. As a material of the lead frame 100, a material mainly composed of copper is desirable. This is because copper has both excellent thermal conductivity and electrical conductivity. In order to improve the workability and thermal conductivity of the lead frame 100, the copper material used as the lead frame 100 is selected from a group of at least Sn, Zr, Ni, Si, Zn, P, Fe, etc. other than copper. It is desirable to use an alloy made of at least one kind of material. For example, an alloy containing Cu as a main component and Sn added thereto (hereinafter referred to as Cu + Sn) can be used. In the case of a Cu + Sn alloy, for example, by adding Sn to 0.1 wt% or more and less than 0.15 wt%, the softening temperature can be increased to 400 ° C. For comparison, the lead frame 100 was fabricated using Sn-free copper (Cu> 99.96 wt%). However, although the electrical conductivity was low, distortion might occur in the completed heat dissipation board. Therefore, when a detailed examination was made, the softening point of the material was as low as about 200 ° C., so when the component was later mounted (soldering) or when reliability was confirmed after mounting the light emitting element 106 (repetition test of heat generation / cooling). Etc.). On the other hand, when a copper-based material with Cu + Sn> 99.96 wt% was used, it was not particularly affected by the heat generated by various mounted components and a plurality of LEDs. There was no effect on solderability and die bondability. Therefore, when the softening point of this material was measured, it was found to be 400 ° C. Thus, it is desirable to add some elements mainly composed of copper. In the case of Zr as an element added to copper, a range of 0.015 wt% or more and 0.15 wt% or less is desirable. When the amount added is less than 0.015 wt%, the effect of increasing the softening temperature may be small. On the other hand, if the amount added is more than 0.15 wt%, the electrical characteristics may be affected. Also, the softening temperature can be increased by adding Ni, Si, Zn, P or the like. In this case, Ni is preferably 0.1 wt% or more and less than 5 wt%, Si is 0.01 wt% or more and 2 wt% or less, Zn is 0.1 wt% or more and less than 5 wt%, and P is preferably 0.005 wt% or more and less than 0.1 wt%. . And these elements can make the softening point of a copper raw material high by adding single or multiple in this range. In addition, when there are few addition amounts than the ratio described here, the softening point raise effect may be low. Moreover, when there are more than the ratio described here, there exists a possibility of affecting the electrical conductivity. Similarly, in the case of Fe, 0.1 wt% or more and 5 wt% or less is desirable, and in the case of Cr, 0.05 wt% or more and 1 wt% or less are desirable. These elements are the same as those described above.

The tensile strength of the copper alloy used for the lead frame 100 is desirably 600 N / mm ² or less. In the case of a material having a tensile strength exceeding 600 N / mm ² , the workability of the lead frame 100 may be affected. Further, such a material having a high tensile strength tends to increase its electric resistance, so that it may not be suitable for high current applications such as LEDs used in the first embodiment. On the other hand, by setting the tensile strength to 600 N / mm ² or less (and if the lead frame 100 requires fine and complicated processing, desirably 400 N / mm ² or less), the springback (pressure even if bent to the required angle) If it is removed, it will be repelled by the reaction force), and the formation accuracy can be improved. As described above, the material of the lead frame 100 is mainly composed of Cu, whereby the electrical conductivity can be lowered, and further softening can improve the workability, and further the heat dissipation effect by the lead frame 100 can be enhanced. The tensile strength of the copper alloy used for the lead frame 100 is desirably 10 N / mm ² or more. This is because the copper alloy used for the lead frame 100 needs to have a strength higher than the tensile strength (about 30 to 70 N / mm ² ) of general lead-free solder. When the tensile strength of the copper alloy used for the lead frame 100 is less than 10 N / mm ² , when the light emitting element 106, the driving semiconductor component, the chip component, and the like are soldered and mounted on the lead frame 100, the lead frame 100 is not the solder portion. There is a possibility of cohesive failure at the part.

  It should be noted that the surface of the lead frame 100 exposed from the heat transfer resin 102 (the light emitting element 106 or a mounting surface of a control IC or a chip component (not shown)) is previously soldered so as to improve solderability. By forming the layer and the tin layer, it is possible to improve the component mountability to the lead frame 100 which has a large heat capacity and is difficult to solder compared to the glass epoxy substrate and the like, and it is possible to prevent the wiring from being rusted. Note that it is desirable not to form a solder layer on the surface (or the embedded surface) in contact with the heat transfer resin 102 of the lead frame 100. When a solder layer or a tin layer is formed on the surface in contact with the heat transfer resin 102 in this way, this layer becomes soft during soldering, which affects the adhesion (or bond strength) between the lead frame 100 and the heat transfer resin 102. There is. 1 to 8, the solder layer and the tin layer are not shown.

The metal metal plate 104 is made of aluminum, copper, or an alloy containing them as a main component with good thermal conductivity. In particular, in the present embodiment, the thickness of the metal plate 104 is 1 mm, but the thickness can be designed according to the specifications of a backlight or the like (note that if the thickness of the metal plate 104 is 0.1 mm or less, heat dissipation and (If the thickness of the metal plate 104 exceeds 5 mm, it is disadvantageous in terms of weight.) The metal plate 104 is not only a plate-like one, but also fin portions (or uneven portions) for increasing the surface area on the surface opposite to the surface on which the heat transfer resin 102 is formed in order to further improve heat dissipation. May be formed. The linear expansion coefficient is 8 × 10 ⁻⁶ / ° C. to 20 × 10 ⁻⁶ / ° C. By bringing the linear expansion coefficient close to the linear expansion coefficients of the metal plate 104 and the light emitting element 106, warpage and distortion of the entire substrate can be reduced. In addition, when these components are surface-mounted, matching the thermal expansion coefficients with each other is also important in terms of reliability. The metal plate 104 can be screwed to another heat radiating plate (not shown).

  As the lead frame 100, it is possible to use a plate material 124 mainly made of copper, at least a part of which is punched in advance. The thickness of the lead frame 100 is desirably 0.1 mm or greater and 1.0 mm or less (more desirably 0.3 mm or greater and 0.5 mm or less). This is because a large current (for example, 30 A to 150 A, which may further increase depending on the number of LEDs to be driven) is required to control a large number of light emitting elements 106 such as LEDs. Moreover, when the thickness of the lead frame 100 is less than 0.10 mm, pressing may be difficult. If the thickness of the lead frame 100 exceeds 1 mm, pattern miniaturization may be affected at the time of punching with a press. However, in the case of the present invention, when the light emitting element 106 is finely mounted, it can be mounted not on the lead frame 100 but on the ceramic wiring substrate 108 capable of forming a fine pattern.

  It is not desirable to use a copper foil (for example, a thickness of 10 microns to 50 microns) instead of the lead frame 100. In the case of the present invention, heat generated in the light emitting element 106 such as an LED is diffused widely through the lead frame 100. Therefore, the greater the thickness of the lead frame 100, the more effective the thermal diffusion through the lead frame 100. On the other hand, when a copper foil is used instead of the lead frame 100, the thickness of the copper foil is thinner than that of the lead frame 100, which may make it difficult to thermally diffuse.

  Further, it is not necessary to mount all the heating elements on the ceramic wiring board 108. The ceramic wiring board 108 can be reduced in size by selecting only elements that generate heat and mounting them on the ceramic wiring board 108. In addition, variations in element temperatures of a plurality of elements can be suppressed. Some of the heating elements may be mounted on the lead frame 100. In this way, the cost can be further reduced by separating the part mounted on the ceramic wiring substrate 108 and the part mounted on the lead frame 100. Further, as the ceramic plate 122, a highly heat conductive member such as a commercially available alumina substrate or alumina nitride substrate can be used. Further, the ceramic plate 122 has a size of several centimeters to several tens of centimeters, and a circuit pattern (for example, as shown in FIG. You can make a large number of pieces. A plurality of ceramic wiring boards 108 as shown in FIG. 4B can be manufactured by manufacturing a plurality of pieces in this way and then dividing them into pieces by break grooves (cutting holes) or laser.

  Thus, in the case of the present invention, the electronic component for which heat generation is a problem is mounted on the ceramic wiring substrate 108 with high heat dissipation, and the heat generated in the electronic component is transferred to the metal plate via the ceramic wiring substrate 108. 104 will escape. Further, by making part of the wiring 120 the lead frame 100, the area of the ceramic wiring substrate 108 can be reduced, and the large current handling, good workability, high heat dissipation, etc. that are the characteristics of the lead frame 100 can be utilized. It is possible to further expand the applications of the heat dissipation substrate.

  Thus, a plurality of lead frames 100 electrically connected to the ceramic wiring board 108 on which the wiring is formed on at least one surface, the metal plate 104 for fixing the ceramic wiring board 108, the wiring 120 on the ceramic wiring board 108, and the like. Are fixed by a heat transfer resin 102 made of a ceramic filler and a thermosetting resin, thereby improving the heat dissipation and workability of the heat dissipation substrate.

  Further, the ceramic wiring board 108 formed on the metal plate 104 and having the wiring 120 formed on at least one surface, a plurality of lead frames 100, a heat transfer resin 102 made of a ceramic filler and a thermosetting resin, The lead frame 100 of the heat dissipating substrate is electrically insulated from the metal plate 104 by the heat transfer resin 102, and one end thereof is electrically connected to the wiring 120 formed on the ceramic wiring substrate 108, The other end protrudes from the heat transfer resin 102 and serves as an extraction electrode, thereby improving the heat dissipation and workability of the heat dissipation substrate.

  Then, between the lead frame 100 processed into a predetermined pattern and the metal plate 104, a ceramic wiring board 108 with wiring formed in advance on the surface, and a heat transfer resin 102 made of a ceramic filler and a thermosetting resin are set. The heat transfer resin 102 is thermally cured into a predetermined shape using a mold, and the heat sink resin 102 is integrated by integrating the metal plate 104, the lead frame 100, and the ceramic wiring board 108 with the heat transfer resin 102. To manufacture.

  In addition, a lead frame 100 in which a ceramic wiring board 108 having wiring formed on at least one surface is processed into a predetermined pattern on a metal plate 104 fixed to the surface, and a heat transfer resin made of a ceramic filler and a thermosetting resin. 102 is set, the heat transfer resin 102 is thermally cured into a predetermined shape using a mold, and the metal plate 104, the lead frame 100, and the ceramic wiring board 108 are integrated with the heat transfer resin 102. To manufacture a heat dissipation board. In this way, the handleability of the heat dissipation substrate can be improved.

  Note that it is not necessary that one end of every lead frame 100 be the ceramic wiring board 108 or the extraction electrode. The lead frame 100 may have a floating island shape (or a floating state in which the lead frame 100 is not connected to the ceramic wiring substrate 108 or the external power source). In this way, by forming some of the lead frames 100 in a floating island shape, various circuit patterns can be formed by the lead frames 100 themselves, so that the area of the ceramic wiring board 108 can be reduced accordingly.

  Moreover, it is not necessary to mount all the components on the ceramic wiring board 108. By mounting components on the lead frame 100, the ceramic wiring board 108 can be downsized. Also, heat generated from components mounted on the lead frame 100 can be radiated from the lead frame 100 to the metal plate 104 via the ceramic wiring substrate 108 or via the heat transfer resin 102.

  As described above, by using the high heat dissipation substrate, the manufacturing method thereof, and the light emitting module using the high heat dissipation substrate according to the present invention, a power supply circuit that requires heat dissipation for a plasma television or a vehicle, or a backlight for a liquid crystal television. A light emitting module or the like can be provided, which can be applied to downsizing of devices and high color rendering.

A perspective view and a sectional view of the heat dissipation board in the first embodiment Top view and sectional view explaining the heat dissipation mechanism of the heat dissipation board Circuit diagram for emitting light from multiple light emitting elements such as LEDs A perspective view and a top view for explaining a ceramic wiring board Sectional view showing structure of ceramic wiring board Sectional drawing explaining the manufacturing method of a heat sink Perspective view showing how metal plates, ceramic wiring boards, lead frames, etc. are fixed with heat transfer resin A perspective view explaining how to mount components on the completed heat dissipation board Sectional drawing which shows an example of the conventional light emitting module

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Lead frame 102 Heat transfer resin 104 Metal plate 106 Light emitting element 108 Ceramic wiring board 110 Arrow 112 Resistance 114 Overcoat 116 Window 118 Dotted line 120 Wiring 122 Ceramic board 124 Board material

Claims (13)

A ceramic wiring board in which wiring is formed on at least one surface, a metal plate for fixing the ceramic wiring board,
A wiring on the ceramic wiring board and a plurality of electrically connected lead frames,
A heat dissipation substrate fixed by a heat transfer resin made of a ceramic filler and a thermosetting resin. A ceramic wiring board fixed on a metal plate and having wiring formed on at least one surface; and
Multiple lead frames,
A heat transfer resin comprising a ceramic filler and a thermosetting resin;
Of the heat dissipation board consisting of
The lead frame is electrically insulated from the metal plate by the heat transfer resin, and one end thereof is electrically connected to the wiring formed on the ceramic wiring board, and the other end protrudes from the heat transfer resin. Heat dissipation board that is an electrode. The ceramic wiring board has wiring mainly composed of silver or copper on its surface,
A protective layer made of an insulating layer mainly composed of a resin or glass for protecting the wiring,
The heat dissipation board according to claim 1, wherein the heat dissipation board is provided. The ceramic wiring board has a plurality of wirings formed on its surface,
A resistance element or a protection element for connecting between the wirings,
The heat dissipation board according to claim 1, wherein the heat dissipation board is provided. The heat dissipation substrate according to any one of claims 1 and 2, wherein the ceramic wiring substrate and the metal plate are joined with a metal member, a resin material, or a glass material. The heat dissipation board according to claim 1, wherein the metal plate is larger than the ceramic wiring board. The heat dissipation board according to claim 1, wherein the wiring of the ceramic wiring board and the lead frame are electrically connected by soldering, welding, bumping, or a physical method. The heat transfer resin is selected from at least one thermosetting resin selected from an epoxy resin, a phenol resin, and a cyanate resin, and AlN, Al ₂ O ₃ , MgO, SiO ₂ , SiC, Si ₃ N ₄ , and BN. The heat dissipation according to claim 1, wherein the heat conductivity is 1 W / (m · K) or more and 20 W / (m · K) or less. substrate. Sn is 0.1 wt% to 0.15 wt%, Zr is 0.015 wt% to 0.15 wt%, Ni is 0.1 wt% to 5 wt%, Si is 0.01 wt% to 2 wt%, Zn is Lead frame mainly composed of copper containing at least one selected from the group of 0.1 wt% to 5 wt%, P is 0.005 wt% to 0.1 wt%, and Fe is 0.1 wt% to 5 wt%. The heat dissipation board according to claim 1, wherein the heat dissipation board is used. A lead frame processed into a predetermined pattern;
Between metal plates,
A ceramic wiring board having wiring formed in advance on the surface;
Set heat transfer resin consisting of ceramic filler and thermosetting resin,
Thermosetting the heat transfer resin into a predetermined shape using a mold,
A method of manufacturing a heat dissipation board, wherein the metal plate, the lead frame, and the ceramic wiring board are integrated with the heat transfer resin. A ceramic wiring board with wiring formed on at least one surface is placed on a metal plate fixed to the surface.
A lead frame processed into a predetermined pattern;
Set heat transfer resin consisting of ceramic filler and thermosetting resin,
Thermosetting the heat transfer resin into a predetermined shape using a mold,
A method of manufacturing a heat dissipation board, wherein the metal plate, the lead frame, and the ceramic wiring board are integrated with the heat transfer resin. A ceramic wiring board in which wiring is formed on at least one surface, a metal plate for fixing the ceramic wiring board,
A wiring on the ceramic wiring board and a plurality of electrically connected lead frames,
Of the heat dissipation board fixed by the heat transfer resin made of ceramic filler and thermosetting resin,
A light emitting module comprising a plurality of light emitting elements mounted on the ceramic wiring board. A ceramic wiring board fixed on a metal plate and having wiring formed on at least one surface; and
Multiple lead frames,
A heat transfer resin comprising a ceramic filler and a thermosetting resin;
Of the heat dissipation board consisting of
The lead frame is electrically insulated from the metal plate by the heat transfer resin, and one end thereof is electrically connected to the wiring formed on the ceramic wiring board, and the other end protrudes from the heat transfer resin. Of the heat dissipation substrate that is the electrode,
A light emitting module comprising a plurality of light emitting elements mounted on the ceramic wiring board.

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