JP2007184542A - LIGHT EMITTING MODULE, ITS MANUFACTURING METHOD, AND BACKLIGHT DEVICE USING THE SAME - Google Patents

Abstract

An object of the present invention is to provide a small light emitting module excellent in heat dissipation, a manufacturing method thereof, and a backlight device using the same.
SOLUTION: A metal substrate 3, a plurality of lead frames 1a and 1b mainly composed of aluminum bent so as to form a concave portion, an inorganic filler for joining the metal substrate 3 and the lead frames 1a and 1b, and thermosetting. A light emitting module in which a heat conductive resin 2 made of a conductive resin and a plurality of light emitting elements 8 are mounted on a lead frame, and at least one surface of the lead frames 1a and 1b facing the metal substrate 3 is anodized film 7 Cover with.
[Selection] Figure 2

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, the color display range is expanded, the luminance of the light emitting element is further increased (a large current needs to flow), and a large number of light emitting elements are mounted at high density. There is a demand for a light emitting module with excellent heat dissipation.
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 lead frame, an insulator having excellent thermal conductivity, and a metal substrate are integrated to form a light emitting module excellent in heat dissipation and high brightness, a method for manufacturing the same, and An object of the present invention is to provide a backlight device using the same.

  In order to solve the above problems, the present invention directly mounts a light emitting element such as an LED on a lead frame excellent in heat dissipation and light reflectivity, and further forms an anodic oxide film excellent in thermal conductivity on the back surface. The lead frame coated in this manner can be efficiently radiated by bonding it to a heat radiating metal substrate through a thin heat conductive resin.

  The light emitting module of the present invention, the light emitting module obtained by the manufacturing method thereof, and the backlight device using the same condense light emitted by light emitting elements such as LEDs and semiconductor lasers in the same direction, Heat dissipation and luminous efficiency can be efficiently diffused and dissipated by joining the metal substrate with a thin thermal conductive resin through a thin insulating film with excellent thermal conductivity formed on one side. A compact light emitting module and a method for manufacturing the same can be realized, and further, a backlight device such as a thin liquid crystal with excellent heat dissipation can be realized by configuring a backlight device using the light emitting module. be able to.

(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.

  In FIG. 1 and FIG. 2, reference numeral 1 denotes a lead frame having aluminum as a main component and having excellent thermal conductivity. This lead frame 1 is composed of a lead frame 1a as an anode electrode and a lead frame 1b as a ground electrode. ing.

  An anodic oxide film 7 having excellent insulation and thermal conductivity is formed on one surface of the lead frame 1. This anodic oxide film 7 forms a dense thin film made of aluminum oxide, and this anodic oxide film 7 is known as an alumite film.

  Since titanium can form the same anodic oxide film 7 having excellent insulating properties, the same effect can be exhibited.

  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 includes a metal substrate 3 having a high heat conductivity. Are joined. Here, there is a problem that the thermal conductivity of the thermal conductive resin 2 is lower than that of the lead frame 1 and the metal substrate 3.

  However, it is impossible to directly join the lead frame 1 and the metal substrate 3 in terms of electrical circuits, and it is indispensable to always join each via an insulating material. Here, the thermal conductivity of the heat conductive resin 2 is large and governs the heat dissipation characteristics of the light emitting module.

  Therefore, in order to achieve both insulation and thermal conductivity, an anodic oxide film 7 having excellent insulation and thermal conductivity is formed as a thin film on one surface of the lead frame 1 and formed thinly via the anodic oxide film 7. The thermally conductive resin 2 and the metal substrate 3 are joined.

  Usually, when the heat conductive resin 2 is formed thin, a part of the lead frame 1 and the metal substrate 3 come into contact with each other to cause a short circuit. Therefore, in order not to cause this short circuit failure, it is necessary to design the heat conductive resin 2 to have a thickness that can ensure insulation in consideration of manufacturing variations (for example, 50 to 300 μm).

  On the other hand, by forming the anodic oxide film 7 formed in a thin film shape, the main role is that the thermal conductive resin 2 is joined, and the insulating property can be reliably ensured by the anodic oxide film 7. Even if the heat conductive resin 2 is formed to be extremely thin, the electrical characteristics are not hindered, and the lead frame 1 and the metal substrate 3 can be joined with the shortest dimension.

  As a result, heat generated from the LED 8 which is a light emitting element can be efficiently conducted from the lead frame 1 to the metal substrate 3, and the light emitting module having such a configuration is small in size and excellent in light emitting efficiency. Modules can be realized.

  Further, since the surface of the anodic oxide film 7 has innumerable fine holes, it is possible to increase the bonding force with the heat conductive resin 2 and realize a substrate structure having a high bonding strength. Can do.

  1 and 2, the anodic oxide film 7 is formed on the entire back surface of the lead frame 1. However, the anodic oxide film 7 is formed in an area facing the metal substrate 3 through at least the heat conductive resin 2. The effect can be demonstrated.

  In addition, since the anodic oxide film 7 has higher thermal conductivity and better insulation than the thermally conductive resin 2, a light emitting module with excellent heat dissipation can be realized.

  Further, since the anodic oxide film 7 can be formed by using an electrochemical process, the thickness can be controlled with high accuracy, and insulation can be ensured if the thickness is at least 100 nm or more. There is no practical problem if it has a withstand voltage insulation characteristic of at least 500 V / μm. And the thickness of 2 micrometers or less is preferable. If the thickness exceeds 2 μm, the thermal conductivity of the anodic oxide film 7 is lower than that of the lead frame 1 and the metal substrate 3 which are metallic materials, so that heat dissipation is hindered and defects such as cracks occur in the anodic oxide film 7 due to stress. Or

  The anodic oxide film 7 can be formed by anodizing aluminum in an electrolyte such as dilute sulfuric acid.

  As described above, the distance between the lead frame 1 and the metal substrate 3 is made extremely close by the synergistic effect of the thin anodic oxide film 7 having excellent insulating properties and the thermally conductive resin 2 having excellent bonding properties. Thus, a light emitting module excellent in insulation and thermal conductivity can be realized.

  Next, 8 is an LED that emits red, blue, green, white, or the like, and 4 is an arrow that indicates the 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.

  Further, the lead frame 1a is individually divided so as to be compatible with the LED 8 having any characteristics. In this way, by configuring the lead frame 1a as an individual divided electrode structure, the applied voltage or applied current to the LED 8 can be individually controlled, so that the luminance can be individually controlled.

  When the LED 8 is selected and used in advance, the lead frame 1a can have a common electrode structure as in the lead frame 1b. As a result, the lead frame 1a is in a continuous state, and the horizontal direction is set. Since the thermal conductivity is increased, a light emitting module with better heat dissipation can be realized.

  The lead frames 1a and 1b are fixed in an insulated state on the metal substrate 3 so as to be embedded in the heat conductive resin 2, and the lead frames 1a and 1b are interposed via 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 has bump electrodes 9 extending over the lead frame 1a and the lead frame 1b. Has been implemented through.

  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 aluminum having excellent heat dissipation, so that the lead frame 1 exerts 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 formed using a metal thin film material mainly composed of silver or nickel having a high light reflectance 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, by processing the lead frames 1a and 1b into a tapered shape or a curved surface shape (or a parabolic shape or the like), the light emitted from the side surface of the LED 8 can be controlled to be reflected in the direction of the arrow 4, and the light emitting module The effect that the brightness of the can be further increased can be exhibited.

  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 (polymethyl methacrylate) or a silicon-based transparent resin. Moreover, 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.

  Moreover, it is desirable to use a soft transparent resin (having a hardness lower than that of an epoxy resin) such as a silicon resin as the transparent 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 difficult 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 metal substrate 3 as much as possible (and more uniformly), heat diffusion from the lead frames 1a and 1b to the metal substrate 3 is achieved. Increases sex. Thereby, the heat generated in the LED 8 is transferred to the lead frames 1a and 1b. By devising the connection destination of the lead frames 1a and 1b, it is possible to dissipate a considerable amount of heat to the outside through the lead frames 1a and 1b. Further, the lead frames 1a and 1b are formed thin on the back surface. Since it has a structure that can diffuse to the metal substrate 3 through the thermally conductive resin 2, a light emitting module that can efficiently diffuse the heat generated in the LED 8 through the metal substrate 3 can be realized. Since heat is radiated by combining the lead frames 1a and 1b used as the electrodes and the heat radiating plate with the metal substrate 3 for heat radiating as described above, it is possible to mount a plurality of LEDs 8 having high luminance characteristics at high density. The light emitting module which can be realized is realizable.

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 50 μm is appropriate (if it is less than 0.1 μm, dispersion into the resin may be difficult). 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 2 kinds of average particle size of the large and small, it is possible to fill the Al ₂ O ₃ of smaller average particle size in the gap Al ₂ O ₃ of greater average particle size, the Al ₂ O ₃ It can be filled at a high concentration up to 90% by weight. As a result, the heat conductivity of the heat conductive resin 2 is about 5 W / (m · K). The inorganic filler may contain at least one selected from the group consisting of MgO, BN, SiC, Si ₃ N ₄ and AlN excellent in thermal conductivity 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 transferred to the metal substrate 3. However, the insulation resistance becomes a problem, and if it is too thick, the thermal resistance increases. The optimum thickness may be set to 50 μm or less in consideration of the withstand voltage and thermal resistance.

  As described above, the heat generated from the LED 8 is first dissipated by conducting heat laterally from the lead frames 1a and 1b. This is because the lead frames 1a and 1b are made of aluminum with high thermal conductivity. Next, the heat transferred to the lead frames 1 a and 1 b is transferred to the anodic oxide film 7 and is conducted to the metal substrate 3 through the heat conductive resin 2. At this time, since the back surface of the lead frames 1a and 1b is covered with the anodic oxide film 7 in a thin film state, the insulation is ensured. Thermal conductivity to the metal substrate 3 can be increased. For example, even if the lead frames 1a and 1b and the metal substrate 3 come into contact with each other due to manufacturing variations, a short circuit occurs because the anodized film 7 is formed on the back surfaces of the lead frames 1a and 1b. Does not happen.

  And the heat | fever of the metal substrate 3 can be set as the structure excellent in heat dissipation by devising the connection structure. For example, heat can be efficiently radiated by transmitting to a heat sink or the like.

  The metal substrate 3 is preferably aluminum, copper, or an alloy containing them as a main component, which has good thermal conductivity.

  In addition, when aluminum is used for the metal substrate 3, one surface of the metal substrate 3 is anodized, and one surface of the anodized metal substrate 3 and the back surface of the lead frame 1 are joined to face each other. The effect can be demonstrated.

  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. At this time, it is preferable to select and mount elements that emit light of the same wavelength. This is because the voltage or current applied to the LED 8 needs to be constant.

  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 also widely on the side wall surface, and it is desirable that the side wall surface be 50 to 95%. 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.

  An anodic oxide film 7 having a thickness of about 3000 mm is formed on the back surface of the lead frame 1. The anodic oxide film 7 can be formed at a predetermined location by forming a pattern using a photoresist material.

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

  4 shows a state in which the thermally conductive resin 2 and the metal substrate 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 predetermined light emitting module.

  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 composed of predetermined copper is punched into a predetermined shape using a press or the like, and an anodic oxide film 7 is formed on the lower surface side. This is referred to as a lead frame 1. The anodic oxide film 7 may be formed in the form of a sheet-like metal plate, or may be formed after punching.

  And when forming the reflective film 5, it is good to form the thin film which has silver etc. as a main component on at least one surface of a sheet-like metal plate (The reflective film 5 is abbreviate | omitted in FIGS. 5-10). .

  Next, as shown in FIG. 5, a lower mold 10 and a mold 11 are set, and a metal substrate 3 having a 1 mm-thickness main component processed into a predetermined dimension is placed therein. An uncured sheet-like thermally conductive resin 2 is set on the metal substrate 3. 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 11, 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.

  After that, as shown in FIG. 7, the lead frame 1 and the metal substrate 3 are integrated with the heat conductive resin 2 by taking out from the molding die, thereby producing a molded product.

  Next, as shown in FIG. 8, the LED 8 is mounted by bump mounting using a solder bump 9 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 that has been required to be handled as a continuous hoop is cut by using a die or the like to be 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 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 having excellent thermal conductivity. 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 50 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 aluminum as a main component. This is because aluminum has both excellent thermal conductivity and electrical conductivity, and the insulating property, reliability, and thermal conductivity of the anodized film 7 are excellent.

The tensile strength of the aluminum alloy 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 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. As described above, the lead frame material is a lead frame 1 mainly composed of aluminum, which realizes high electrical conductivity, softens it to improve workability, and further has excellent thermal conductivity. 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.

  The metal substrate 3 is made of aluminum, copper, or an alloy containing them as a main component, which has good thermal conductivity. In particular, in the first embodiment, the thickness of the metal substrate 3 is 1 mm, but the thickness can be designed according to the specifications of the light emitting module or the like (when the thickness of the metal substrate 3 is less than 0.1 mm, heat dissipation and strength In addition, if the thickness of the metal substrate 3 exceeds 5 mm, it is disadvantageous in terms of thickness and weight). The metal substrate 3 is not only a plate-shaped substrate, but also fins (or uneven portions) are formed on the opposite surface joined to the heat conductive resin 2 to increase the surface area in order to further improve heat dissipation. In addition, the heat dissipation can be enhanced.

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 metal substrate 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 metal substrate 3 so that it can be screwed to another heat radiating plate (not shown).

  Further, as the lead frame 1, at least a part of which is punched into a three-dimensional recess shape in advance can be used. 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 showing a configuration of an edge light which is an example of a backlight device according to Embodiment 2 of the present invention.

  The edge light shown in FIG. 11 conceptually shows the structure of an edge light used for a liquid crystal backlight that is required to be thin using a light emitting element such as an LED. The structure of the edge light is at least one surface of the LED 8. A light emitting module made up of lead frames 41a and 41b, a heat conductive resin 2 and a metal substrate 3 coated with an anodic oxide film 7 excellent in heat conductivity, a light guide plate 42, a diffusion plate 43, a reflection plate 44 and a frame The light emitted from the LED 8 as the light source is incident from the side surface of the light guide plate 42, the light from the LED 8 is guided in a planar shape using the light guide plate 42, and then uniform using the diffusion plate 43. A thin surface light source is realized by diffusing light while controlling the directivity and directivity. The reflecting 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. The diffusion plate 43 and the reflection plate 44 can be used as necessary. In addition, a prism or the like can be used to improve the optical characteristics of the edge light.

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

  In the configuration of the edge light in the second embodiment, the most characteristic point is that at least one surface of the lead frames 41a and 41b facing the metal substrate 3 is covered with the anodic oxide film 7 having excellent thermal conductivity. That is, the lead frames 41a and 41b are bent and used as a reflector, and one end of the lead frame 41a is joined to the edge light frame 45. At this time, the light of the LED 8 can be efficiently concentrated on the light guide plate 42 by forming the reflection film 5 on the surfaces of the lead frames 41a and 41b. In the edge light, the light emitting elements are usually arranged in a line on a single thin rod-shaped substrate. In order to realize a thin edge light, the LED 8 as the light emitting element is used. The configuration of the edge light that can efficiently dissipate heat is very important. With the configuration shown in FIG. 11, heat generated from the LED 8 is radiated to the lead frames 41a and 41b, and then the lead frame. Heat is radiated from 41a to the frame 45. And, it is effective from the viewpoint of heat dissipation that the one end of the lead frame 41a and the frame 45 are joined with a larger joining length along the rod-like length direction.

  At this time, the frame 45 is a structural material for reinforcement by using a material having excellent thermal conductivity such as a metal and can have a structure having a large heat radiation area on the back side of the display device, etc. Heat generated from the LED 8 can be efficiently radiated. 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, the thermal conductivity to the frame 45 can be further increased. At this time, the anodic oxide film 7 is formed on the back surface of the lead frame 41a. This anodic oxide film 7 is intended to improve the insulation between the lead frames 41a and 41b and the metal substrate 3. The purpose of forming the insulating film can be realized by providing at least one surface of the lead frames 41 a and 41 b facing the metal substrate 3.

  Further, when the frame 45 cannot be used as a ground electrode, it is preferable to bond the lead frame 41 a to the frame 45 after performing an insulation treatment through the heat conductive resin 2. This makes it possible to realize a thin edge light, although the heat dissipation is slightly lower than the direct bonding.

  When it is necessary to insulate the lead frame 41a and the frame 45, the anodic oxide film 7 is formed up to the tip of the lead frame 41a, and then the lead frame 41a is joined to the frame 45 through the thermal conductive resin 2. It is also possible to do. Further, the heat dissipation can be further improved by bonding the other lead frame 41b to the frame 45 after the insulating treatment via the heat conductive resin 2 and then joining them.

  Furthermore, by joining the metal substrate 3 to the frame 45, it is possible to further improve heat dissipation. When it is necessary to maintain the insulation between the metal substrate 3 and the frame 45, the metal substrate 3 can be bonded to the metal substrate 3 through the heat conductive resin 2. 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 metal substrate 3. And since this metal substrate 3 uses the metal material excellent in heat conductivity, it can thermally radiate to the flame | frame 45 efficiently. Further, it is effective against stress such as deflection when the metal substrate 3 is joined to a part of the frame 45 through the heat conductive resin 2 to improve heat dissipation and a very thin edge light is realized. Edge light 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 liquid crystal TVs having excellent heat dissipation.

The perspective view of the light emitting module in Embodiment 1 of this invention Cross section A plan view of a lead frame for explaining the manufacturing method Plan view Sectional drawing for demonstrating the manufacturing method Cross section Cross section Cross section Cross section Cross section 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 Thermal conductive resin 3 Metal substrate 4 The arrow which shows the direction of light 5 Reflective film 6 Recessed part 7 Anodized film 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 (19)

A metal substrate, a plurality of lead frames mainly composed of aluminum bent so as to form a recess, a thermally conductive resin composed of an inorganic filler and a thermosetting resin for joining the metal substrate and the lead frame, and A light emitting module comprising a plurality of light emitting elements mounted on a lead frame, wherein at least one surface of the lead frame facing the metal substrate is covered with an anodized film. The light emitting module according to claim 1, wherein the thickness of the anodized film is 2 μm or less. 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 3, 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 5, wherein light emitting elements that emit light having 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 that occupies 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 light emitting module according to claim 1, wherein the thickness of the heat conductive resin is 50 μm or less. 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 including 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 coated with an anodized film on one side and punched and a metal substrate;
Placing the metal substrate, the thermally conductive resin, and one surface of a lead frame coated with an anodic oxide film in a mold so as to face the metal substrate;
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. A metal substrate, a plurality of lead frames mainly composed of aluminum bent so as to form a recess, a thermally conductive resin composed of an inorganic filler and a thermosetting resin for joining the metal substrate and the lead frame, and A plurality of light emitting elements are mounted on a lead frame, and a light emitting module in which at least one surface of the lead frame facing the metal substrate is covered with an anodic oxide film, and light from the light emitting module incident from the incident surface on the side surface is irradiated. A backlight device comprising a light guide plate and a frame, wherein one end of at least one lead frame is joined to a part of the frame. The backlight device according to claim 16, 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 16, wherein the metal substrate is joined to a part of the frame. The backlight device according to claim 18, wherein the metal substrate is joined to a part of the frame via a heat conductive resin.

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