JP2007184237A - Light-emitting module, its manufacturing method, and backlight device using light-emitting module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small and lightweight light-emitting module excellent in heat dissipation property, its manufacturing method, and a backlight device using the light-emitting module. <P>SOLUTION: The light-emitting module is composed of an oriented graphite sheet 3, lead frames 1a, 1b bent into a tapered shape and mainly made of copper, a thermally-conductive resin 2 including an inorganic filler and a thermosetting resin between the oriented graphite sheet 3 and each lead frame 1a, 1b, and a plurality of light-emitting elements 8, which are mounted on the lead frames 1a, 1b, so as to efficiently diffuse heat to the oriented graphite sheet 3 while having a role as an electrode and a role for heat dissipation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light emitting module used for a backlight such as a thin display or a thin illuminating device, a manufacturing method thereof, and a backlight device using the same.

  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. 12 is a cross-sectional view showing an example of a conventional light emitting module. In FIG. 12, a light emitting element 102 is mounted in a recess formed in the ceramic substrate 101. Further, the plurality of ceramic substrates 101 are fixed on the heat radiating plate 103, and the plurality of ceramic substrates 101 are electrically connected by a connection substrate 105 having a window portion 104. The direction 106 of light emitted from the light emitting element 102 is emitted to the outside through the window 104 formed in the connection substrate 105. In FIG. 12, the wiring in the ceramic substrate 101 having the recesses and the connection substrate 105, the wiring pattern of the light emitting element 102, and the like are not shown.

  The light emitting module having such a configuration is used as a backlight for a liquid crystal display or the like.

On the other hand, from the display device side such as a liquid crystal TV, there is a light emitting module with excellent heat dissipation capable of expanding the color display range, further increasing the brightness of the light emitting elements, and mounting a large number of light emitting elements at a high density. Requested.
JP 2004-311791 A

  However, in the conventional configuration, since the substrate on which the light emitting element is mounted is the ceramic substrate 101, there is a problem that it is disadvantageous in workability and heat dissipation, and the present invention solves the conventional problem. Instead of the ceramic substrate 101, a compact and lightweight light emitting module with excellent heat dissipation and its manufacture by integrating a lead frame, an insulator with excellent thermal conductivity, and an oriented graphite sheet. It is an object to provide a method and a backlight device using the method.

  In order to solve the above-described problems, the present invention directly mounts a light emitting element such as an LED on a lead frame having excellent heat dissipation and light reflectivity, and further heats the lead frame through a heat conductive resin. This is transmitted to the oriented graphite sheet for heat dissipation formed on the back surface.

  The light emitting module of the present invention, the manufacturing method thereof, and the light emitting module obtained by the backlight device using the same condense light emitted by light emitting elements such as LEDs and semiconductor lasers in the same direction and generate generated heat. Can be efficiently diffused and dissipated by the lead frame and the oriented graphite sheet, so that a compact and lightweight light emitting module with excellent heat dissipation and luminous efficiency and its manufacturing method can be realized. By configuring the backlight device, it is possible to realize a backlight device for a thin liquid crystal having excellent heat dissipation.

(Embodiment 1)
Hereinafter, the light emitting module in Embodiment 1 of this invention is demonstrated using drawing.

  FIG. 1 is a perspective view showing a configuration of a light emitting module according to Embodiment 1 of the present invention, and FIG. 2 is a cross-sectional view of the light emitting module of FIG.

  1 and 2, reference numeral 1 denotes a lead frame having excellent thermal conductivity, such as copper. The lead frame 1 is composed of a lead frame 1a as an anode electrode and a lead frame 1b as a ground electrode. Reference numeral 2 denotes a heat conductive resin made of a composite material such as an inorganic filler having an excellent heat conductivity and an epoxy resin, and the heat conductive resin 2 is an oriented graphite having a high heat conductivity. The sheet 3 is joined.

  Reference numeral 8 denotes an LED that is a light emitting element such as red, blue, green, or white. Reference numeral 4 denotes an arrow that indicates a traveling direction of light emitted from the LED 8. The LED 8 is shown as an example of a light emitting element such as a semiconductor laser, and it goes without saying that it can be applied to other light emitting elements.

  Furthermore, the lead frame 1 includes a lead frame 1b used as a ground electrode and a lead frame 1a used as an anode electrode. The lead frame 1a is individually divided so as to be compatible with LEDs having any characteristics. By configuring the lead frame 1a as an individual electrode in this way, the applied voltage or applied current to the LED 8 can be individually controlled, so that the luminance can be individually controlled.

  When the LEDs 8 are selected and used in advance, the lead frame 1a can have a common electrode structure in the same manner as the lead frame 1b, thereby realizing a light emitting module with better heat dissipation. it can.

  The lead frames 1a and 1b are fixed in an insulated state on the oriented graphite sheet 3 so as to be embedded in the heat conductive resin 2. The lead frames 1a and 1b are fixed to the heat conductive resin 2. Are insulated from each other. And since this heat conductive resin 2 is excellent in insulation and heat conductivity, the heat | fever discharge | released from LED8 can be diffused and radiated without concentration of heat_generation | fever occurring.

  Next, by bending the lead frames 1a and 1b into a tapered shape, a recess 6 as shown in FIG. 2 is formed, and the LED 8 passes through the bump electrode 9 so as to straddle the lead frames 1a and 1b. Implemented.

  The LED 8 can be mounted by wire bonding or flip chip mounting using conductive resin, solder, or the like, but can be appropriately selected and mounted.

  In this way, the lead frames 1a and 1b are bent into a taper shape, and the light emitted from the LED 8 is directed in a predetermined direction through the lead frames 1a and 1b by designing the lead frames 1a and 1b to have as large an area as possible. By reflecting light, a light emitting module having excellent light emission efficiency can be realized.

  At this time, the lead frames 1a and 1b are formed of a metal material mainly composed of copper, which has excellent heat dissipation, so that the lead frame 1 exhibits an effect as an electrode, a light reflector and a heat sink. Thus, a small light emitting module with excellent luminous efficiency can be realized.

  Further, by forming a reflective film 5 made of a metal thin film material mainly composed of silver or nickel having a high light reflectivity on the exposed surface of the lead frames 1a and 1b, the luminous efficiency is further improved. A high light emitting module can be realized.

  Further, the lead frames 1a and 1b are processed into a taper shape or a curved surface shape (or a parabolic shape or the like), so that the direction of the light emitted from the side surface of the LED 8 can be controlled as indicated by the arrow 4, and the light emitting module. The effect that the brightness of the can be further increased can be exhibited.

  In addition, the oriented graphite sheet 3 is highly oriented graphite having a structure close to a single crystal made by a method of graphitizing a polymer film by thermal decomposition, and with respect to the plane direction (a-b plane), It is a heat dissipation material having high thermal conductivity.

  And such an oriented graphite sheet 3 is obtained by heat-treating a polyimide film or the like at a temperature of about 3000 ° C. in an electric furnace controlled in atmosphere, and then rolling to obtain a flexible oriented graphite sheet 3. Can do. The orientation graphite sheet 3 has physical properties similar to those of single crystal graphite, and does not cause scale-like peeling or residual acid, and is high-quality and resistant to bending and rich in flexibility. An oriented graphite sheet 3 having excellent thermal conductivity is obtained.

  The oriented graphite sheet 3 has a thermal conductivity of 400 to 1700 W / (m · K). For example, the thermal conductivity of copper having excellent thermal conductivity is 390 W / (m · K). On the other hand, the thermal conductivity of the oriented graphite sheet has characteristics that exceed this, and since its specific gravity can exhibit lightness of 1/9 that of copper, it has excellent heat dissipation, A light-emitting module that can be reduced in weight can be realized. And since the heat conductivity of this orientation graphite sheet 3 can be designed according to the characteristic of a light emitting module suitably, the freedom degree of heat design can be raised. Therefore, the light-emitting module having excellent thermal conductivity in the plane direction can be obtained by bonding the oriented graphite sheet 3 having such light weight and excellent thermal conductivity to the back surface of the LED 8 via the thermal conductive resin 2. In addition, the electronic device can be reduced in weight when used in a light-emitting device of a portable electronic device that is required to be reduced in weight.

  Next, the LED 8 is usually hermetically sealed using a transparent resin or the like that can ensure the reliability of the light emitting element and function as a lens (not shown). As this transparent resin, it is desirable to use PMMA (polymethacrylate) or silicon-based transparent resin. In addition, when an epoxy resin is used, it is necessary to add a UV inhibitor for preventing yellowing of the epoxy resin. This is because the epoxy resin may be yellowed by light when a white or blue light emitting element is used for the LED 8.

  In addition, it is desirable to use a soft resin (having a hardness lower than that of an epoxy resin) such as a silicon resin. By using this flexible resin material, it is possible to prevent stress concentration on the connection portion between the LED 8 and the lead frames 1a and 1b when the LED 8 generates heat and thermally expands.

  Similarly, stress concentration on the gold wire can be reduced when the LED 8 and the lead frames 1a and 1b are connected by wire bonding (the gold wire is less likely to be cut).

  Further, by reducing the thickness of the heat conductive resin 2 that insulates between the lead frames 1a and 1b and the oriented graphite sheet 3 as much as possible (and more uniformly), the lead frames 1a and 1b can be changed from the oriented graphite sheet 3. Increases thermal diffusivity. As a result, the heat generated by the LED 8 is transferred to the lead frames 1a and 1b, and a considerable amount of heat can be radiated to the outside through the lead frames 1a and 1b by devising the connection destination of the lead frames 1a and 1b. In addition, since the back surfaces of the lead frames 1a and 1b have a structure capable of diffusing to the oriented graphite sheet 3 via the heat conductive resin 2, the heat generated by the LED 8 through the oriented graphite sheet 3 can be efficiently used. A light emitting module that can diffuse well can be realized. Thus, since it has the structure which can radiate heat by combining with lead frame 1a, 1b used as an electrode and a heat sink, and the orientation graphite sheet 3 for heat radiation, LED8 which has several high-intensity characteristics is high. A light emitting module that can be mounted at a high density can be realized.

Moreover, it is desirable to use the thermally conductive resin 2 in which an inorganic filler having excellent thermal conductivity is dispersed in a thermosetting resin. In particular, the inorganic filler is substantially spherical and has a diameter of 0. 0. 1 to 100 μm is appropriate (if it is less than 0.1 μm, it may be difficult to disperse in the resin). Therefore, the filling amount of the inorganic filler in the heat conductive resin 2 is filled at a high concentration of 70 to 95% by weight in order to increase the heat conductivity. In Embodiment 1, the inorganic filler is a mixture of two types of Al ₂ O ₃ having an average particle diameter of 3 μm and an average particle diameter of 12 μm. 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 conductive resin 2 is about 5 W / (m · K). The inorganic filler may include at least one selected from the group consisting of MgO, BN, SiC, Si ₃ N ₄ and AlN instead of Al ₂ O ₃ .

  In addition, as a thermosetting insulating resin, at least 1 type of resin is included among an epoxy resin, a phenol resin, and cyanate resin. These resins are excellent in heat resistance and electrical insulation. If the thickness of the heat conductive resin 2 is reduced, the heat generated from the LEDs 8 attached to the lead frames 1a and 1b can be easily transmitted to the oriented graphite sheet 3. However, if the thickness is too thick, the heat resistance increases. Therefore, the optimum thickness may be set to 50 to 1000 μm in consideration of the withstand voltage and the thermal resistance.

  As described above, the heat generated from the LED 8 is first dissipated by conducting heat in the lateral direction from the lead frames 1a and 1b. This is because the lead frames 1a and 1b are made of copper having high thermal conductivity. Further, the heat transferred to the lead frames 1 a and 1 b is thermally conducted to the oriented graphite sheet 3 through the heat conductive resin 2. And the heat | fever of the orientation graphite sheet 3 can be thermally radiated efficiently by transmitting to a heat sink etc., for example. In this way, the heat generated in the LED 8 can be diffused efficiently and at high speed, so that the LED 8 can be efficiently cooled, and a plurality of LEDs 8 (and LEDs that require high heat dissipation) are contained in the recess 6. Even) can be mounted with high density.

  As a result, a small, low-profile light emitting module capable of high-density mounting can be realized. Such a light emitting module is particularly effective for a backlight of a liquid crystal display device or the like.

  The plurality of LEDs 8 are supplied with current from the plurality of lead frames 1a and are connected to the ground electrode of the lead frame 1b, thereby emitting light in a predetermined color.

  Further, by mounting the LED 8 that emits light of different wavelengths, a light emitting module that covers a desired wide wavelength band can be realized.

  Also, by mounting one lead frame 1b as one common ground electrode, the other lead frame 1a as one common anode electrode, and mounting the light emitting element in parallel on the ground electrode and the anode electrode, In particular, in the lead frame 1a, it is possible to realize a light-emitting module mounted with high density and excellent in thermal conductivity. And at this time, it is preferable to mount LED8 which light-emits the light of the same wavelength.

  The color of the heat conductive resin 2 is preferably white (or colorless near white) from the viewpoint of reflectance. This is because the effect of reflecting from the exposed heat conductive resin 2 can be exhibited. On the other hand, when it is colored black, red, blue or the like, it becomes difficult to reflect the light emitted from the LED 8 and affects the light emission efficiency.

  In this way, a plurality of LEDs 8 are mounted on the bottom surface of the recess 6 so as to straddle the lead frames 1a and 1b, and the lead frames 1a and 1b are further bent into a tapered shape and used as a reflector. It is preferable to form it widely also on the side wall surface, and it is desirable to make it 50 to 95% of the side wall surface. Thereby, the light emitted efficiently can be collected and reflected in a predetermined direction on the front surface.

  In addition, when the area ratio which occupies for the side wall of lead frame 1a, 1b is less than 50%, there exists a possibility of reducing the light reflection amount by the surface of lead frame 1a, 1b. If it exceeds 95% (when the exposed ratio of the heat conductive resin 2 on the side surface is less than 5%), the possibility of short-circuiting between the lead frames 1a or between the lead frames 1a and 1b increases.

  In addition, the shape of the recess 6 is desirably a shape that narrows toward the bottom, and a reflector having an arbitrary shape can be obtained by appropriately bending it into a predetermined shape from the characteristics of the light emitting element or the light emitting characteristics required for the backlight. It is possible to realize a light emitting module that can be freely designed with light reflection efficiency.

  Next, the manufacturing method of the light emitting module in this Embodiment 1 is demonstrated using drawing. 3 and 4 are plan views for explaining the method for manufacturing the light emitting module according to Embodiment 1, and FIGS. 5 to 10 are cross-sectional views.

  FIG. 3 is a plan view of the lead frame 1 according to the first embodiment, which is used as a continuous hoop. The lead frame 1a can be singulated, and the lead frame 1b is a continuous metal piece.

  A guide hole 20 is provided to mechanically transport the hoop-shaped lead frame 1. A position where the LED 8 is mounted across the lead frame 1a and the lead frame 1b is indicated by a dotted line.

  A dotted line 30 indicates a position where the lead frame 1 is bent.

  FIG. 4 shows a state in which the thermally conductive resin 2 and the oriented graphite sheet 3 are joined and the LED 8 is mounted, and then punched out to cut off an excess portion of the lead frame 1 as a light emitting module having a predetermined shape. Yes.

  Next, a manufacturing method for manufacturing a light emitting module will be described in detail.

  5-10 is sectional drawing which shows an example of the manufacturing method of the light emitting module in this Embodiment 1. FIG. In FIG. 5, 10 is a lower mold, 11 is a mold, 12 is an upper mold, and 13 is a dirt prevention film for preventing the lead frame 1 from being stained.

  First, a sheet-like metal plate mainly made of predetermined copper is punched into a predetermined shape using a press or the like, and this is used as the lead frame 1.

  At this time, when the reflective film 5 is formed, a thin film mainly composed of silver or the like is preferably formed on at least one surface of the sheet-like metal plate (the reflective film 5 is not shown in FIGS. 5 to 10). ).

  Next, the lower mold 10 and the mold 11 are set, and the oriented graphite sheet 3 having a thickness of 300 μm processed into a predetermined dimension is placed therein, and the uncured graphite sheet 3 is uncured on the oriented graphite sheet 3. The sheet-like heat conductive resin 2 in a state is set. At this time, the heat conductive resin 2 is preliminarily kneaded with an inorganic filler having excellent heat conductivity and an epoxy resin, etc. at a predetermined blending ratio, and then made into a sheet shape by a rolling roll or the like so as to have a predetermined thickness. It can be produced by processing into The thickness of the rolled sheet is preferably a thickness that takes into account the amount of the heat conductive resin 2 that fills the gaps in the lead frame 1.

  Then, the lead frame 1 is positioned on the heat conductive resin 2 and set between the mold 11 and the upper mold 12.

  Next, as shown in FIG. 6, the lead frame 1 is pressed against the heat conductive resin 2 while lowering the upper mold 12 by a pressing device (not shown in FIG. 6), and the temperature is set at a predetermined temperature. Heat cure in time. At this time, by setting the antifouling film 13 between the lead frame 1 and the mold 12, when the lead frame 1 is pressed into the heat conductive resin 2, the surface of the lead frame 1 is stained. In addition to preventing, the generation of air residue can be prevented.

  Thereafter, as shown in FIG. 7, the molded product in which the lead frame 1 and the oriented graphite sheet 3 are integrated with the heat conductive resin 2 is produced by taking out from the molding die.

  Next, as shown in FIG. 8, the LED 8 is mounted with bumps 9 by a solder bump connection technique or the like so as to straddle the lead frame 1a and the lead frame 1b.

  Thereafter, as shown in FIG. 9, an extra portion of the lead frame 1 necessary for handling as a continuous hoop is cut using a mold or the like to cut into an outer shape of a predetermined light emitting module.

  Then, as shown in FIG. 10, it is bent along a predetermined bending position 30 using a die or the like in a tapered shape. The bent shape can be easily processed into a predetermined shape according to the shape and size of the light emitting module.

  Then, the light emitting module as shown in FIG. 1 is completed by covering with a transparent resin or the like as necessary.

Next, the heat conductive resin 2 that is an insulating material will be described in more detail. The thermally conductive resin 2 is composed of a filler and an insulating resin. As this filler, an inorganic filler is desirable. The inorganic filler preferably includes at least one selected from the group consisting of Al ₂ O ₃ , MgO, BN, SiC, Si ₃ N ₄ and AlN. If MgO is used, the linear thermal expansion coefficient can be increased, and if BN is used, the linear thermal expansion coefficient can be decreased. In this way, the thermal conductive resin 2 having a thermal conductivity of 1 to 10 W / (m · K) 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. Further, if the thermal conductivity is to be made higher than 10 W / (m · K), it is necessary to increase the amount of inorganic filler, which may affect the workability during pressing.

  The insulating resin is preferably a thermosetting resin, and specifically includes at least one selected from the group consisting of an epoxy resin, a phenol resin, and an isocyanate resin.

In addition, the inorganic filler has a substantially spherical shape and a diameter of 0.1 to 100 μm. The smaller the particle size, the better the filling rate into the resin. Therefore, the filling amount (or content) of the inorganic filler in the heat conductive resin 2 is filled at a high concentration of 70 to 95% by weight in order to increase the heat conductivity. In particular, in the first embodiment, the inorganic filler is a mixture of two types of Al ₂ O ₃ having an average particle diameter of 3 μm and an average particle diameter of 12 μm. 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 conductive resin 2 is about 5 W / (m · K). And when the filling rate of an inorganic filler is less than 70 weight%, thermal conductivity may fall. Further, when the filling rate (or content rate) of the inorganic filler exceeds 95% by weight, the moldability of the uncured thermal conductive resin 2 may be affected. There is a possibility of affecting the adhesiveness (for example, when embedded or attached to the surface).

  The thermosetting insulating resin contains at least one kind of resin among epoxy resin, phenol resin and cyanate resin. These resins are excellent in heat resistance and electrical insulation.

  Next, the material of the lead frame 1 will be described. The lead frame 1 is preferably made of copper as a main material. This is because copper has both excellent thermal conductivity and electrical conductivity. In order to improve the workability and thermal conductivity as the lead frame 1, the copper material different from that of the lead frame 1 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 in the range of 0.1 to 0.15 wt%, the softening temperature can be increased to 400 ° C. For comparison, when the lead frame 1 was manufactured using Sn-free copper (Cu> 99.96 wt%), the electrical conductivity was low. It may occur. As a result of detailed examination, the softening point of the material is as low as about 200 ° C., so the reliability after mounting the LED 8 (repetition of heat generation / cooling, etc.) when mounting the component in the subsequent process (soldering) It was predicted that there was a possibility of deformation.

  On the other hand, when a copper material with Cu + Sn> 99.96 wt% was used, it was not particularly affected by the heat generated by various mounted components and the plurality of LEDs 8. And 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 to be added to copper, a range of 0.015 to 0.15 wt% is desirable. When the addition amount is lower 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, a composition range of 0.1 to 5 wt% for Ni, 0.01 to 2 wt% for Si, 0.1 to 5 wt% for Zn, and 0.005 to 0.1 wt% for P is desirable.

  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 raise effect of a softening point 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 to 5 wt% and in the case of Cr 0.05 to 1 wt% are desirable. These elements are the same as those described above.

Incidentally, the tensile strength of the copper alloy 600N / 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 1 may be affected. In addition, such a material having high tensile strength tends to increase its electrical resistance, and thus may not be suitable for high current applications such as the LED 8 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 1 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, the occurrence of rebound by reaction force) can be suppressed, and the formation accuracy of the recess 6 can be improved. Thus, as the lead frame material, high conductivity is realized by making the lead frame 1 mainly composed of Cu, softening improves workability, and furthermore, it has excellent thermal conductivity, so that the heat dissipation effect. Can also be enhanced.

  A solder layer is previously applied to the surface of the lead frame 1 exposed from the heat conductive resin 2 (the LED 8 or a mounting surface of a control IC or a chip component (not shown)). By forming the tin layer, it is possible to improve the mountability of components on the lead frame 1 which has a larger heat capacity than the glass epoxy substrate or the like and is difficult to solder, and to prevent rusting of the wiring. It is desirable that no solder layer be formed on the surface (or embedded surface) of the lead frame 1 that is in contact with the heat conductive resin 2. When a solder layer or a tin layer is formed on the surface in contact with the heat conductive resin 2 in this way, this layer becomes soft during soldering, which affects the adhesion (or bond strength) between the lead frame 1 and the heat conductive resin 2. May give. 1 and 2, the solder layer and the tin layer are not shown.

  In Embodiment 1, the thickness of the oriented graphite sheet 3 is 300 μm, but the thickness can be designed according to the specifications of the light emitting module or the like (when the thickness of the oriented graphite sheet 3 is less than 20 μm, the heat dissipation performance If the thickness of the oriented graphite sheet 3 exceeds 300 μm, it is disadvantageous in terms of productivity and cost).

In addition, by setting the total expansion coefficient to 8 to 20 × 10 ⁻⁶ / ° C., it is possible to reduce the warpage and distortion of the entire substrate of the light emitting module by bringing it closer to the linear expansion coefficient of the oriented graphite sheet 3 and the LED 8. In addition, when the mounting components are surface-mounted, it is important in terms of reliability to match the thermal expansion coefficients with each other.

  It is also possible to process the oriented graphite sheet 3 so that it can be screwed to another heat radiating plate (not shown).

  Further, as the lead frame 1, it is possible to use at least a part of which is punched into a three-dimensional recess shape in advance. The thickness of the lead frame 1 is desirably 0.1 to 1.0 mm (more desirably 0.4 to 0.8 mm). This is because a large current (for example, 30 to 150 A, which may be further increased depending on the number of LEDs to be driven) is required to control the LEDs. Further, if the thickness of the lead frame 1 exceeds 1 mm, pattern miniaturization may be affected when punching with a press.

(Embodiment 2)
Hereinafter, a backlight device according to Embodiment 2 of the present invention will be described with reference to the drawings.

  FIG. 11 is a cross-sectional view illustrating a configuration of an edge light which is an example of a backlight device according to Embodiment 2 of the present invention, and is used for a liquid crystal backlight that is required to be thin using a light emitting element such as an LED chip. The structure of an edge light is shown. As shown in FIG. 11, the structure is LED8, lead frame 41a, 41b, the light emitting module which consists of the heat conductive resin 2, and the orientation graphite sheet 3, the light guide plate 42, the diffuser plate 43, the reflecting plate 44, and a flame | frame. 45, and the light emitted from the light emitting module is incident from the side surface of the light guide plate 42. After the light is guided in a planar shape using the light guide plate 42, the diffusion plate 43 is used for uniformity and directivity. A thin planar light source is realized by diffusing light while controlling properties. The reflection plate 44 is used to make a planar light source that efficiently emits light in one direction by reflecting light emitted from the light guide plate 42 in the direction of the diffusion plate 43. The diffusion plate 43 and the reflection plate 44 can be used as necessary. Further, in order to improve the optical characteristics of the edge light, it is also possible to use a prism or the like arranged on the upper surface of the diffusion plate 43.

  In addition, description of the optical control circuit part etc. which perform optical control of the brightness | luminance of the some LED8 mounted, color gamut, color tone, etc. is abbreviate | omitted here.

  In the configuration of the edge light according to the second embodiment, the most characteristic point is that the lead frames 41a and 41b are bent, the lead frames 41a and 41b are used as a reflector, and one end of the lead frame 41a is used. It is configured to be joined to the frame 45 of the edge light.

  At this time, the light of the LED 8 can be more efficiently concentrated on the light guide plate 42 by forming the reflective film 5 on the surfaces of the lead frames 41a and 41b. In general, the edge light is arranged by arranging the LEDs 8 in a row on a single thin rod-shaped substrate. In order to realize a thin edge light, the heat radiation from the light emitting element is efficiently performed. The configuration of the edge light that can dissipate heat is very important. With the configuration as shown in FIG. 11, the heat generated from the LED 8 is conducted to the lead frames 41a and 41b, and then the frame from the lead frame 41a to the frame. Heat conduction to 45. Further, it is effective from the viewpoint of thermal conductivity that the one end of the lead frame 41a and the frame 45 are joined to have a larger joining length along the rod-like length direction.

  The frame 45 is a structural material for reinforcement by using a material having excellent thermal conductivity such as metal, and can have a structure having a large heat radiation area on the back side of the display device. The heat generated from the LED 8 can be radiated well. It is also possible to add a further cooling structure such as a heat radiating fin or a heat pipe to the frame 45.

  The lead frame 41a joined to the frame 45 is preferably on the ground terminal side. Thereby, it is possible to dissipate heat without lowering the thermal conductivity.

  In addition, when the frame 45 cannot be used as a ground electrode, it is preferable that the lead frame 41 a be joined to the frame 45 after insulating treatment through the heat conductive resin 2. This makes it possible to realize an edge light capable of radiating heat in a state of being electrically insulated, although the heat radiation performance is slightly lower than that of direct bonding. In this case, it is preferable that the other lead frame 41 b is also bonded to the frame 45 after being insulated through the heat conductive resin 2. Thereby, heat dissipation can be improved more.

  Furthermore, by joining the oriented graphite sheet 3 to the frame 45, the heat dissipation can be further improved. As a result, heat is radiated from the lead frames 41 a and 41 b to the heat conductive resin 2 and then to the oriented graphite sheet 3. The oriented graphite sheet 3 is excellent in thermal conductivity and lighter than a metal material, so that it can efficiently dissipate heat to the frame 45 and realize a lightweight backlight device. be able to.

  Moreover, when it is necessary to ensure insulation, heat dissipation can be improved by joining the oriented graphite sheet 3 to a part of the frame 45 via the heat conductive resin 2. In addition, when a thin edge light is realized, an edge light that is effective against stress such as deflection can be realized.

  As described above, by using the light emitting module, the manufacturing method thereof, and the backlight device using the light emitting module according to the present invention, high heat dissipation and miniaturization can be realized, so that a large number of light emitting elements are mounted with high density. Therefore, it is useful as a light source for backlights, projectors and the like of small and light liquid crystal TVs having excellent heat dissipation.

The perspective view of the light emitting module in Embodiment 1 of this invention Sectional view A plan view of a lead frame for explaining the manufacturing method Plan view Sectional drawing for demonstrating the manufacturing method Sectional view Sectional view Sectional view Sectional view Sectional view Sectional drawing of the backlight apparatus in Embodiment 2 of this invention Sectional view of a conventional light emitting module

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1a, 1b Lead frame 2 Thermally conductive resin 3 Oriented graphite sheet 4 Arrow which shows the direction of light 5 Reflective film 6 Recessed part 8 LED
9 Bump 10 Lower mold 11 Mold 12 Upper mold 13 Antifouling film 20 Guide hole 30 Bending position 41a, 41b Lead frame 42 Light guide plate 43 Diffuser plate 44 Reflector plate 45 Frame

Claims (21)

Thermal conductivity composed of an oriented graphite sheet, a plurality of lead frames mainly composed of copper bent so as to form a recess, an inorganic filler for joining the oriented graphite sheet and the lead frame, and a thermosetting resin And a light emitting module in which a plurality of light emitting elements are mounted on the lead frame. The light emitting module according to claim 1, wherein a thermal conductivity in a plane direction of the oriented graphite sheet is 400 W / (m · K) or more. The light emitting module according to claim 1, wherein the orientational graphite sheet has a thickness of 20 to 300 μm. The light emitting module according to claim 1, wherein one lead frame is a common ground electrode, the other lead frame is a plurality of independent anode electrodes, and the light emitting element is mounted on the anode electrode independent of the ground electrode. . The light emitting module according to claim 4, wherein light emitting elements that emit light of different wavelengths are mounted. The light emitting module according to claim 1, wherein one lead frame is used as a common ground electrode, the other lead frame is used as a common anode electrode, and light emitting elements are mounted in parallel so as to straddle the ground electrode and the anode electrode. . The light emitting module according to claim 6, wherein light emitting elements that emit light of the same wavelength are mounted in parallel. The light emitting module according to claim 1, wherein a reflective film is provided on the exposed surface of the lead frame. The light emitting module according to claim 1, wherein the lead frame is a lead frame occupying an area of 50 to 95% of a side surface forming a taper. The light emitting module according to claim 1, wherein the lead frame has a thickness of 0.10 to 1.0 mm. The lead frame is made of 0.1 to 0.15 wt% Sn, 0.015 to 0.15 wt% Zr, 0.1 to 5 wt% Ni, 0.01 to 2 wt% Si, 0.1 to Zn 2. The light emitting device according to claim 1, wherein the lead frame is a lead frame mainly composed of copper containing at least one selected from the group consisting of 5 wt%, P of 0.005 to 0.1 wt%, and Fe of 0.1 to 5 wt%. module. The light emitting module according to claim 1, wherein the thickness of the heat conductive resin is 50 to 500 μm. The light emitting module according to claim 1, wherein the heat conductivity of the heat conductive resin is 1 to 10 W / (m · K). The light emitting module according to claim 1, wherein the inorganic filler is an inorganic filler containing at least one selected from the group consisting of Al ₂ O ₃ , MgO, BN, SiC, Si ₃ N ₄ and AlN. The light emitting module according to claim 1, wherein the thermosetting resin is a thermosetting resin containing at least one selected from the group consisting of an epoxy resin, a phenol resin, and an isocyanate resin. The light emitting module according to claim 1, wherein the heat conductive resin is white. A step of placing a thermally conductive resin between a lead frame punched in advance and an oriented graphite sheet;
Placing the oriented graphite sheet, the lead frame and the thermally conductive resin in a mold; and
A process of heat-curing the heat-conductive resin in a state of being pressed and heated by the press and integrated into a molded body; and
A method for manufacturing a light emitting module, comprising a step of mounting a light emitting element so as to straddle a part of a lead frame of the molded body and then sealing with a transparent resin. An oriented graphite sheet, a plurality of lead frames mainly composed of copper bent so as to form a recess, an inorganic filler and a thermosetting resin for joining the oriented graphite sheet to the lead frames and the lead frames A heat conductive resin, a light emitting module having a plurality of light emitting elements mounted on the lead frame, a light guide plate for irradiating light of the light emitting module incident from an incident surface on a side surface, and a frame. A backlight device, wherein one end of at least one lead frame is joined to a part of the frame. The backlight device according to claim 18, wherein one end of the lead frame is joined to a part of the frame via a heat conductive resin. The backlight device according to claim 18, wherein the oriented graphite sheet is joined to a part of the frame. The backlight device according to claim 20, wherein the oriented graphite sheet is joined to a part of the frame via a heat conductive resin.

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