JP2007194522A - Light-emitting module, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve processability by using a lead frame, an insulator, a light reflection material, and a metal plate instead of a ceramic substrate. <P>SOLUTION: In a light-emitting module, the lead frame 100 fixed by a wall section 116 made of a light reflection resin 104, and the metal plate 112 for radiating heat are formed integrally via a heat-conductive resin 102. Thus heat generated from the light-emitting element 108 is transferred to the metal plate 112 from the lead frame 100 via the heat-conductive resin 102, light generated from the light-emitting element 108 is reflected to the front by the light reflection resin 104 exposed to the gap between the lead frames 100, and a reflection ring 114 that can be attached later after packaging the light-emitting element 108, thus enhancing the luminous efficiency and heat radiation efficiency in the light-emitting module. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light emitting module used for a backlight of a display device having a backlight such as a liquid crystal television and a manufacturing method thereof.

  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, since the ceramic element 1 is difficult to process and expensive, there has been a demand for a heat dissipation substrate that is cheaper and has excellent workability.

  On the other hand, the display device side including the liquid crystal TV is desired to expand the color display range. In response to such needs, white LEDs and the like have limitations, and in recent years, red (red), green (green), and blue (blue) single-color light emitting elements, and further purple, orange, red purple, cobalt Attempts have been made to expand the color display range (specifically, the CIE color system, etc.) by adding a special color light emitting element that emits a special color such as blue.

  When such a light emitting module as shown in FIG. 9 is used to meet such needs, while mounting each of these light emitting elements one by one in the concave portion of the ceramic substrate 1, a uniform mixed color (colored and white) is produced as a whole, It is necessary to adjust the color balance (for example, white balance described later). On the other hand, it is known that the luminous efficiency of solid light emitting devices such as LEDs decreases as the temperature rises. Furthermore, the degree of decrease in luminous efficiency with respect to temperature varies depending on the emission color of the LED. For this reason, for example, immediately after the liquid crystal TV is turned on, the LED portion is at room temperature (for example, 25 ° C.), and thus the temperature of the LED portion increases (for example, 40 ° C. → 50 ° C.) even if white balance is maintained. → 60 ° C.), for example, a phenomenon such as a reduction in red light emission efficiency may occur, and color reproducibility and backlight luminance may also change.

  On the other hand, as shown in FIG. 9, when the ceramic substrate 1 on which the light emitting elements 2 such as LEDs are mounted one by one is arranged on the heat radiating plate 3, it is advantageous from the heat radiating surface. It becomes difficult to produce a white color by mixing light (or to produce a white color having high color rendering properties by mixing RGB + special colors).

Therefore, it is possible to mount a large number of light-emitting elements that can handle higher brightness of the light-emitting elements (necessary to pass a large current) and multi-LEDs (mounting a plurality of LEDs with high density). There is a demand for light-emitting modules that have high processability and excellent heat dissipation.
JP 2004-311791 A

  However, the conventional configuration has a problem that the heat dissipation substrate on which the light emitting element is mounted is a ceramic substrate, which is disadvantageous in terms of workability and cost.

  The present invention solves the above-described conventional problems, and provides a light-emitting module with good processability and a method for manufacturing the same by using a lead frame, an insulator, a reflector, and a metal plate instead of a ceramic substrate. For the purpose.

  In order to solve the above problems, the present invention mounts a light emitting element such as an LED directly on a lead frame having high heat dissipation, and reflects light from the light emitting element by a ring-shaped reflecting material. The generated heat is transmitted from the lead frame to the heat radiating metal plate formed on the back surface through the heat conducting resin.

  The light emitting module obtained by the light emitting module of the present invention and the manufacturing method thereof can efficiently diffuse the heat generated by the light emitting elements such as LEDs and semiconductor lasers, and can effectively cool the light emitting elements such as LEDs.

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

  1A and 1B are a top view and a cross-sectional view illustrating a light-emitting module according to Embodiment 1, in which FIG. 1A is a top view, and FIGS. 1B and 1C are FIGS. It is sectional drawing in arbitrary parts. In FIG. 1, 100 is a lead frame, 102 is a heat conducting resin, 104 is a light reflecting resin, and 106 is an auxiliary line. Reference numeral 108 denotes a light emitting element, and the light emitting element 108 is a light emitting element such as an LED or a laser. Reference numeral 110 denotes an arrow, 112 denotes a metal plate, 114 denotes a reflection ring, and 116 denotes a wall portion. The auxiliary line 106 a means the reflecting ring 114, and the auxiliary line 106 b means the bent part of the lead frame 100. The wall 116 is made of a light reflecting resin 104 having a high light reflectance. The reflection ring 114 surrounds the light emitting element 108 in, for example, a donut shape, and reflects light emitted from the light emitting element 108 forward as indicated by an arrow 110 shown in FIGS. 1B and 1C. Moreover, although the wall part 116 is formed in the square enclosure shape in FIG. 1 (A), it may be donut shape etc. besides this shape. This is because the function of the wall portion 116 is to play a role of collecting the resin leaked from the reflection ring 114 (corresponding to the transparent resin 118 described with reference to FIGS. 4 and 5) as shown in FIGS.

  The reflection ring 114 is formed on the lead frame 100 in a ring shape (so as to surround the light emitting element 108 in FIG. 1A). The reflecting ring 114 is not integrated with the light reflecting resin 104 or the wall portion 116 made of the light reflecting resin 104 but is removable. By making the reflective ring 114 removable in this way, the reflective ring 114 can be mounted so as to surround the light emitting element 108 after the light emitting element 108 is mounted on the lead frame 100. By setting the reflection ring 114 after mounting the light emitting element 108 in this manner, the light emitting element 108 can be mounted on the lead frame 100 at high density and high speed without the reflection ring 114 interfering. In the first embodiment, the lead frame 100 fixed by the light reflecting resin 104 is further insulated and fixed on the metal plate 112 via the heat conductive resin 102. The light emitted from the light emitting element 108 mounted on the lead frame 100 is reflected forward with high efficiency by the reflection ring 114 and the light reflecting resin 104 in the gap between the lead frames 100.

  First, description will be made with reference to FIG. In FIG. 1A, the lead frame 100 is divided into a plurality of parts and insulated from each other by a heat conductive resin 102. The lead frame 100 is reinforced by a light reflecting resin 104 filled in a gap between the plurality of lead frames 100 and a wall portion 116 made of the light reflecting resin 104. The auxiliary line 106a indicates the slope of the reflecting ring 114 and the like. The auxiliary line 106b indicates the bending position of the lead frame 100. For example, in FIGS. 1B and 1C, the lead frame 100 extending outward from the heat conducting resin 102 is attached to a printed wiring board or the like. To be easy, it means that it is bent.

  In FIG. 1A, a reflection ring 114 is formed in a wall 116, and a plurality of light emitting elements 108 are mounted on the lead frame 100 exposed in the reflection ring 114. Light emitted from the light emitting element 108 is reflected forward with high efficiency by the surface of the lead frame 100, the surface of the light reflecting resin 104 exposed between the lead frames 100, and the reflection ring 114. The light emitting element 108 is formed so as to straddle the plurality of lead frames 100 (note that the light emitting element 108 does not necessarily have to be mounted straddling). Similarly, members such as a wire wire for mounting the light emitting element 108 (wire wire is in the case of wire bonding connection), conductive resin, solder (in the case of flip chip mounting, etc.) are not shown in FIG.

  Note that portions of the plurality of lead frames 100 where the light emitting elements 108 are mounted are fixed by a light reflecting resin 104 instead of the heat conducting resin 102. Further, the periphery of the portion of the lead frame 100 where the light emitting element 108 is mounted is surrounded by a ring-shaped reflecting ring 114 made of the light reflecting resin 104, and the light emitted from the light emitting element 108 passes through the gap between the lead frames. The light is reflected forward by the ring-shaped reflection ring 114 as well as the light reflection resin 104 formed in the above. As a result, the luminous efficiency increases.

  Next, description will be made with reference to FIG. FIG. 1B corresponds to a cross-sectional view at an arbitrary position in FIG. In FIG. 1B, a part of the lead frame 100 is bent, which corresponds to a terminal portion for attaching the light emitting module of the present invention to a printed wiring board or the like (a printed wiring board or the like is not shown). And can be bent as necessary.

  In FIG. 1B, it can be seen that light (indicated by an arrow 110) emitted from the light emitting element 108 mounted on the lead frame 100 is reflected forward by the light reflecting resin 104. Further, the lead frame 100 is fixed to the metal plate 112 via a heat conductive resin 102. In FIG. 1B, the light reflecting resin 104 is not formed between the lead frame 100 and the heat conducting resin 102. This is to suppress the influence on the heat conduction from the lead frame 100 to the metal plate 112 through the heat conducting resin 102, which is generated by the light reflecting resin 104.

  1C corresponds to a cross-sectional view at an arbitrary position in FIG. 1A as in FIG. 1B. As shown in FIG. 1C, light emitted from the light emitting element 108 is reflected by a reflection ring 114 formed of a light reflecting resin 104 as indicated by an arrow 110. As shown in FIG. 1C, by forming the light reflecting resin 104 between the lead frames 100, the light reflectance in the vicinity of the light emitting element 108 can be increased. For this reason, even when a plurality of light emitting elements each having a different emission color are mounted within the area surrounded by the ring-shaped light reflecting resin 104 (or the reflection ring 114), the mixed color (or white color due to the mixed color) can be obtained. Formation) can be facilitated.

  Next, a more detailed description will be given with reference to FIG. FIG. 2 is a diagram showing the shape of the lead frame, which corresponds to a structure obtained by removing the reflection ring 114, the wall 116, the light emitting element 108, and the like from FIG. From FIG. 2, it can be seen that the lead frame 100 is also formed under the ring-shaped reflecting ring 114 and the wall 116. Further, it can be seen that the leading end portion of the lead frame 100 (or the vicinity of the portion where the light emitting element 108 is mounted) is fixed by the light reflecting resin 104.

  As shown in FIG. 2, the light reflectance in the vicinity of the light emitting element 108 can be increased by forming the light reflecting resin 104 between the lead frames 100. For this reason, even when a plurality of light emitting elements each having a different emission color are mounted within the area surrounded by the ring-shaped reflection ring 114, the color mixture (or white formation by color mixture) can be facilitated.

  Next, FIG. 3 illustrates how heat generated in the light emitting element 108 is diffused. FIG. 3 is a diagram showing how heat is diffused. FIG. 3A is a diagram in which the light emitting element 108 and the like are omitted from FIG. 1A, and corresponds to FIG. In FIG. 3A, an arrow 110a is an arrow indicating a direction in which heat is transmitted from the light-emitting element 108 (not illustrated in FIG. 3). 3A that heat generated in the light emitting element 108 (not shown in FIG. 3) is diffused along the lead frame 100 in the direction of the arrow 110a.

  FIG. 3B is a cross-sectional view illustrating a state of heat diffusion in the cross section of FIG. 3B that heat generated in the light-emitting element 108 diffuses along the shape of the lead frame 100 in the direction of the arrow 110b.

  FIG. 3C is a cross-sectional view illustrating a state of heat diffusion in the cross section of FIG. From FIG. 3C, it can be seen that the heat transmitted to the lead frame 100 is diffused to the metal plate 112 through the heat conducting resin 102 as indicated by an arrow 110c.

As the heat conducting 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 becomes difficult to disperse in the resin, and if it exceeds 100 microns, the heat conductive resin 102 is used. Increases the thickness of the material, affecting the thermal diffusivity). Therefore, the amount of the inorganic filler in the heat conducting 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 thermal conductivity of the heat conducting resin 102 is about 5 W / (m · K). 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 .

  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. If the thickness of the heat conducting resin 102 is reduced, the heat generated in the light emitting element 108 attached to the lead frame 100 can be easily transferred to the metal plate 112, but conversely, the insulation breakdown voltage becomes a problem, and if it is too thick, the thermal resistance increases. In view of the withstand voltage and thermal resistance, the optimum thickness may be set to 50 microns or more and 1000 microns or less.

  Thus, in Embodiment 1, by adding a filler having good thermal conductivity as the heat conductive resin 102 and a filler having excellent light reflectivity to the light reflecting resin 104, respectively, thermal conductivity and light reflecting property are added. (Or the formation of white light by mixing different monochromatic lights).

  Note that the color of the heat conducting resin 102 is desirably white. By making the heat conducting resin 102 white, light that cannot be reflected by the light reflecting resin can be reflected forward.

  Note that the reflecting ring 114 is preferably ring-shaped (or donut-shaped). This is to increase the efficiency of light reflection. Further, the shape of the side surface of the reflecting ring 114 can be formed to become narrower toward the bottom, but this is to increase the light reflection efficiency. Needless to say, the reflection direction of light can be optimized by making the side surface of the reflection ring 114 radial, quadratic curve, cubic curve, or the like. Note that the reflection ring 114 can be made of the same material as the light reflection resin 104. When the same material is used, the reflecting ring 114 can be manufactured with high accuracy by a method such as injection molding. The reflecting ring 114 can also be made of a material different from that of the light reflecting resin 104. At this time, in the case of being made of an insulating material (for example, a sintered body such as alumina ceramic), there is no need to electrically insulate between the lead frame 100 and the reflection ring 114. Further, when the reflection ring 114 is made of a metal (for example, a metal molded body such as aluminum), it is necessary to electrically insulate the lead frame 100 and the reflection ring 114. Thus, a short circuit between the lead frame 100 and the reflection ring 114 can be prevented.

(Embodiment 2)
Hereinafter, an example of the manufacturing method of the light emitting module in Embodiment 2 of this invention is demonstrated using FIGS. 4-5 is sectional drawing which shows an example of the manufacturing method of the light emitting module in Embodiment 2, 118 is transparent resin and 120 is a lens.

  4A, it can be seen from a cross section of the lead frame 100 that a part of the lead frame 100 is punched into a fine pattern with a mold or the like. Further, it can be seen from the cross section of the light reflecting resin 104 that the wall portion 116 is formed from the light reflecting resin 104. As shown in FIG. 4B, the lead frame 100 and the light reflecting resin 104 described separately in FIG. 4A are integrated. For this integration, a thermoplastic resin injection molding method using a mold can be used.

  FIG. 4B is a cross-sectional view showing a state in which a part of the lead frame 100 is fixed by the light reflecting resin 104. By fixing a part of the lead frame 100 with the light reflecting resin 104, an effect of preventing the deformation of the lead frame can be obtained. As the light reflecting resin 104, a resin material mainly including a white resin used for manufacturing an LED chip or the like (a white pigment is added as required) can be used. Since such a member can be injection-molded, the wall 116 can be formed simultaneously with the fixing of the lead frame 100. By forming the wall portion 116 in this manner, the strength of the lead frame 100 can be increased. Next, as shown in FIG. 4C, the lead frame 100 is integrated with the heat conductive resin 102 and the metal plate 112. Note that a part of the lead frame 100 can be bent before this integration (not shown).

  FIG. 4C shows a state in which the lead frame 100 is integrated with the heat conductive resin 102 and the metal plate 112. In this integral molding, a press device using a mold can be used. Moreover, the heat conductive resin 102 is hardened by heating at arbitrary temperature (for example, 180 degreeC), for example in the range of 80 to 200 degreeC.

  FIG. 4D shows a state in which the light emitting element 108 is mounted on the lead frame 100. For mounting the light emitting element 108, any mounting method such as solder mounting, mounting using a wire bonder, or flip chip mounting can be selected.

  Next, the reflection ring 114 is mounted as indicated by an arrow 110 in FIG. In addition, a projection 124 (the projection 124 will be described later with reference to FIG. 6) is formed in advance on a part of the reflection ring 114, so that the reflection ring is temporarily fixed to the lead frame 100 or the heat conductive resin 102. it can.

  Next, a transparent resin 118a is poured into a portion surrounded by the reflection ring 114 and cured. As shown in FIG. 5A, the transparent resin 118a may be appropriately filled in the portion surrounded by the reflective ring 114. If necessary, the entire portion surrounded by the reflection ring 114 can be covered with the transparent resin 118a. In this case, as shown in FIG. 5B, it is desirable that the transparent resin 118c overflowing from the reflection ring 114 be received by a gap between the reflection ring 114 and the wall portion 116. In this way, the process can be stabilized.

  FIG. 5C is a cross-sectional view showing a state where the lens 120 is set on the transparent resin 118b. By receiving the overflowing transparent resin 118c outside the reflection ring 114 (or the gap between the reflection ring 114 and the wall 116), the mounting effect of the lens 120 and the flow out of the light emitting module are prevented. Can be prevented. In particular, the transparent resin 118 for protecting the light emitting element 108 is often low-viscosity in order to prevent entrainment of bubbles, and it is known that such a resin easily flows out from a small gap. However, as shown in FIG. 5, by forming a portion corresponding to the tray with the wall 116 and the heat conducting resin 102, unnecessary flow out can be prevented.

  Next, a more detailed description will be given with reference to FIG. FIG. 6 is a perspective view of the reflecting ring. In FIG. 6, the light-emitting element 108 and the lead frame 100 mounted in the reflection ring are not shown. 122 is a groove, and 124 is a protrusion.

  As shown in FIG. 6A, a groove 122 is formed in a part of the reflective ring 114, so that when the transparent resin 118 is introduced using a dispenser or the like as indicated by an arrow 110a, the excess transparent resin 118 is used. Can be stored outside (portion described with reference to FIGS. 5B and 5C) as indicated by an arrow 110b.

  Further, as shown in FIG. 6B, by forming the projection 124 on a part of the reflection ring 114, the alignment can be ensured when the lens 120 is set as indicated by the arrow 110c. If necessary, a concave portion (not shown) corresponding to the protruding portion 124 can be formed in the lens 120.

  Note that the transparent resin 118 that covers the light-emitting element 108 is preferably PMMA (polymethyl methacrylate) or a silicon-based transparent resin. When an epoxy resin is used here, it is necessary to add a UV inhibitor for preventing yellowing of the epoxy. This is because the LED is white, and further, the epoxy resin may be yellowed by blue light. Also, it is desirable to use a soft material such as silicon (having at least a lower hardness than epoxy). By using a soft (flexible) resin material, the light-emitting element 108 generates heat, and stress concentration at the connection portion between the light-emitting element 108 and the lead frame 100 when the thermal expansion occurs can be prevented. Similarly, stress concentration on the gold wire when the light emitting element 108 and the lead frame 100 are bonded and connected can be reduced (the gold wire is difficult to cut).

  Note that the light-emitting element 108 mounted on the light-emitting module is preferably a light-emitting element having at least one kind of different emission colors. Color rendering can be improved by using a plurality of light emitting elements 108 having different light emission colors, and a plurality of these can be mounted at a high density in a region surrounded by one light reflecting resin, thereby improving the color mixing property of each other. It is done. In addition, one or more emission colors of the plurality of light emitting elements 108 may be white. As described above, in the configuration of the second embodiment, by utilizing the excellent heat dissipation, even the light emitting element 108 whose light emission efficiency is easily affected by the temperature (or the degree of influence is different) is affected by the temperature. Hateful. Needless to say, even when the temperature of the light emitting module itself rises, the light emitting elements 108 can be individually controlled via the lead frame 100.

(Embodiment 3)
Hereinafter, an example of another method for manufacturing the light emitting module according to Embodiment 3 of the present invention will be described with reference to FIGS. 7 to 8 are cross-sectional views showing an example of a method for manufacturing a light emitting module in the third embodiment. 7 to 8, reference numeral 126 denotes a spacer portion. The difference between the second embodiment and the third embodiment from FIG. 7 is that light is reflected from the top and bottom of the lead frame 100 (the wall portion 116 covers the top surface of the lead frame 100 and the spacer portion 126 covers the bottom of the lead frame 100) and the side surface. Covering the resin 104 (corresponding to the third embodiment) and covering the top and side surfaces of the lead frame 100 with the light reflecting resin 104 (corresponding to the second embodiment). As shown in the third embodiment, the upper and lower sides and the side surfaces of the lead frame 100 are also covered with the light reflecting resin 104, so that the deformation of the lead frame 100 can be prevented and a short circuit between the lead frame 100 and the metal plate 112 can be prevented. This is because the lead frame 100 and the metal plate 112 are insulated by the multilayer of the light reflecting resin 104 and the heat conducting resin 102. Further, the adhesive strength between the lead frame 100 and the light reflecting resin 104 can be increased.

  FIG. 7A is a cross-sectional view of the lead frame 100 and a cross-sectional view of a member formed of the light reflecting resin 104. Here, the upper portion of the light reflecting resin is the wall portion 116, and the lower portion of the light reflecting resin 104 is the spacer portion 126.

  Next, as shown in FIG. 7B, the back and front of the lead frame 100 are fixed by the light reflecting resin 104. In this step, a technique such as injection molding can be used. In this way, deformation of the lead frame 100 can be prevented. At the same time, the wall 116 can be formed. Further, the light reflecting resin 104 can be embedded in the back surface of the lead frame 100 (on the heat conducting resin 102 side). In this way, a part of the light reflecting resin 104 can be formed at a position where the gap between the lead frames 100 and between the lead frame 100 and the heat conducting resin 102 are avoided from directly under the light emitting element 108. The reason why the light reflecting resin 104 is not formed under the lead frame 100 immediately below the light emitting element 108 is that the heat conduction from the lead frame 100 to the heat conducting resin 102 is not affected.

  Next, the heat conductive resin 102 is used to integrate with the metal plate 112. In this integral molding, a heat press or the like (not shown including a mold or the like) can be used.

  The lead frame 100 fixed with the light reflecting resin 104 and the heat conducting resin 102 are integrated by first preliminarily molding the heat conducting resin 102 and the lead frame 100 (or pregel or pregel molding) and then pressing the metal plate 112. Alternatively, heat curing may be performed. Further, as shown in FIG. 7C, the heat conducting resin 102 may be set between the lead frame 100 and the metal plate 112 and pressed to cure the heat conducting resin 102. Thus, a structure as shown in FIG. 7D is formed.

  FIG. 7D is a cross-sectional view after the integration. As shown in FIG. 7D, it can be seen that the thickness of the heat conductive resin 102 formed between the lead frame 100 and the metal plate 112 is thin and uniform. This is because the spacer portion 126 formed between the lead frame 100 and the metal plate 112 increases the thickness accuracy of the heat conducting resin 102. Here, the spacer portion 126 may have a columnar shape or an independent island shape. By devising the shape of the spacer portion 126 in this way, the wraparound property of the heat conducting resin 102 to the spacer portion 126 can be improved. Then, the light emitting module is completed as shown in FIG. The spacer portion 126 may have a columnar shape (or an independent protrusion shape, an island shape, or a continuous wall shape).

  FIG. 8A is a cross-sectional view after the light-emitting element 108 is mounted. From FIG. 8A, it can be seen that the light-emitting element 108 is mounted inside the wall portion 116. Next, as illustrated in FIG. 8B, the reflective ring 114 is mounted between the light emitting element 108 and the wall portion 116. Then, as illustrated in FIG. 8C, the light-emitting element 108 is protected with a transparent resin 118a. At this time, excess transparent resin 118b can be accumulated between the reflection ring 114 and the wall portion 116.

  FIG. 8D is a cross-sectional view showing a state in which a part of the lead frame 100 is bent. As shown in FIG. 8D, by mounting a part of the lead frame 100, the mountability of the light emitting module to another printed wiring board (not shown) or the like can be improved. In addition, a heat dissipation effect to other printed wiring boards (not shown) can be obtained via the lead frame 100.

  In this way, the thickness of the heat conducting resin 102 can be controlled using the shape of the light reflecting resin 104 (for example, the spacer portion 126). The gap between the metal plate 112 and the lead frame 100 is made constant by the spacer portion 126 formed by the light reflecting resin 104, and the heat conducting resin 102 is filled therebetween. By filling the heat conductive resin 102 between the metal plate 112 and the spacer portion 126 in this way, the heat conductive resin 102 can be made thin and uniform, and the efficiency of heat conduction to the metal plate 112 can be improved. Can do.

  In this way, by forming a part of the light reflecting resin 104 as the spacer portion 126 that holds the gap between the lead frame 100 and the metal plate 112, the molding accuracy of the heat conducting resin 102 between the lead frame 100 and the metal plate 112 can be improved. Enhanced.

  Note that it may be determined as necessary at which stage the lead frame 100 is bent.

Next, the insulating material will be described in more detail. The heat conducting resin 102 is composed of a filler and a resin. The filler is preferably an inorganic filler. The inorganic filler desirably contains at least one selected from the group consisting of Al ₂ O ₃ , MgO, BN, SiO ₂ , SiC, Si ₃ N ₄ , and AlN. When an inorganic filler is used, heat dissipation can be improved, but when using MgO in particular, 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. In this way, the heat conductive 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.

  The 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.

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 conducting resin 102 is filled at a high concentration of 70 to 95% by weight in order to increase the heat 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 thermal conductivity of the heat conducting 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 unheated heat conducting resin 102 may be affected, and the adhesiveness between the heat conducting resin 102 and the lead frame 100 (for example, embedded) Case or when pasted on 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.

  If the thickness of the insulator made of the heat conducting resin 102 is reduced, the heat generated in the light emitting element 108 attached to the lead frame 100 can be easily transferred to the metal plate 112, but conversely, the withstand voltage becomes a problem. Since the thermal resistance increases, the optimum thickness may be set in consideration of the withstand voltage and the thermal resistance.

  Next, the material of the lead frame 100 will be described. The lead frame is preferably made mainly of copper. This is because copper has both excellent thermal conductivity and electrical conductivity. In order to improve the workability and thermal conductivity as a lead frame, 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 comprising at least one material. For example, an alloy (hereinafter referred to as Cu + Sn) in which Cu is a main component and Sn is added thereto 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, when the lead frame 100 was manufactured using Sn-free copper (Cu> 99.96 wt%), the electrical conductivity was low. It was. Therefore, when a detailed examination was made, the softening point of the material was as low as about 200 ° C., so that the reliability (repetition of heat generation / cooling, etc.) at the time of subsequent component mounting (soldering) or after mounting of the light-emitting element 108 was improved. It was expected that it could be deformed. 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% 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, as the lead frame material, the electrical conductivity can be lowered by using Cu as a main component, the workability can be improved by further softening, and the heat dissipation effect by the lead frame 100 can also 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 108, the driving semiconductor component, the chip component, etc. are soldered and mounted on the lead frame 100, the lead frame is not the solder portion. There is a possibility of cohesive failure at 100 parts.

  It should be noted that the solder layer so as to improve the solderability in advance on the surface of the lead frame 100 exposed from the heat conductive resin 102 (the light emitting element 108 or a mounting surface of a control IC or chip component (not shown)). By forming the tin layer, it is possible to improve the component mounting property to the lead frame 100 and to prevent the wiring from being rusted because the heat capacity is large and the soldering is difficult compared with the glass epoxy substrate or the like. It is desirable that no solder layer be formed on the surface of the lead frame 100 that is in contact with the heat conductive resin 102 (or the embedded surface). When a solder layer or a tin layer is formed on the surface in contact with the heat conducting resin 102 in this way, this layer becomes soft during soldering, which may affect the adhesion (or bond strength) between the lead frame 100 and the heat conducting resin 102. . 1 and 2, the solder layer and the tin layer are not shown.

The metal metal plate 112 is made of aluminum, copper, or an alloy containing them as a main component, which has good thermal conductivity. In particular, in the present embodiment, the thickness of the metal plate 112 is 1 mm, but the thickness can be designed according to the specifications of a backlight or the like (in addition, when the thickness of the metal plate 112 is 0.1 mm or less, heat dissipation and (If the thickness of the metal plate 112 exceeds 50 mm, it is disadvantageous in terms of weight.) The metal plate 112 is not only a plate-like material, but also has a fin portion (or uneven portion) to increase the surface area on the surface opposite to the surface on which the insulators are laminated in order to further improve heat dissipation. You may do it. The linear expansion coefficient is 8 × 10 ⁻⁶ / ° C. to 20 × 10 ⁻⁶ / ° C. By bringing the coefficient of linear expansion close to the linear expansion coefficient of the metal plate 112 and the light emitting element 108, 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. Further, the metal plate 112 can be screwed to another heat radiating plate (not shown).

  As the lead frame 100, a metal plate mainly made of copper, at least a part of which is punched in advance, can be used. 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 the 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. Here, it is not desirable to use a copper foil (for example, a thickness of 10 to 50 microns) instead of the lead frame 100. In the case of the present invention, the heat generated in the LED is widely diffused 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, which may make it difficult for heat diffusion.

  As described above, the lead frame 100 mainly composed of copper, a part of which is fixed by the light reflecting resin 104, the metal plate 112, and the inorganic filler formed between the lead frame 100 and the metal plate 112. A part of the light emitting element 108 mounted on the lead frame 100 includes a heat conductive resin 102 that is an insulating layer made of a resin composition containing a thermosetting resin, and a reflective ring 114 that can be attached later. A light emitting module having a structure reflected by the reflecting ring 114 can be provided. The reflective ring 114 is mounted (or retrofitted) after the light emitting element 108 is mounted, so that the mountability of the light emitting element 108 is not affected.

  Thus, a lead frame 100 mainly composed of copper fixed by a wall portion 116 formed of a light reflecting resin 104, a metal plate 112, and the lead frame 100 and the metal plate 112 are formed. A part of the light emitting element 108 which is composed of a heat conductive resin 102 which is an insulating layer made of a resin composition containing an inorganic filler and a thermosetting resin, and a reflective ring 114 and mounted on the lead frame 100, A light emitting module having a structure that is reflected forward by a reflecting ring 114 is provided.

  Similarly, a lead frame 100 mainly composed of copper fixed by a wall portion 116 partially formed of light reflecting resin 104, a metal plate 112, and formed between the lead frame 100 and the metal plate 112. Mounted on the lead frame 100 surrounded by the heat conducting resin 102, which is an insulating layer made of the inorganic filler and the resin composition containing the thermosetting resin, the reflective ring 114, and the reflective ring 114 A part of the transparent resin 118 that includes the light emitting element 108 and protects the light emitting element 108 mounted on the lead frame 100 is a light emitting module having a structure that accumulates in a gap between the reflection ring 114 and the wall 116. provide.

  In such a light emitting module, the insulating material 102 is sandwiched between the lead frame 100, which is partially fixed by the wall portion 116 made of the light reflecting resin 104, and the metal plate 112, and the insulation After the heat conducting resin 102, which is a resin, is cured and the metal plate 112 and the lead frame 100 fixed by the light reflecting resin 104 are integrated, the light emitting element 108 and the reflecting ring 114 are mounted, whereby a light emitting module is obtained. Can be manufactured.

  Similarly, the insulating resin is formed by sandwiching a heat conducting resin 102 as an insulating resin between a lead frame 100 partially fixed by a wall portion 116 made of a light reflecting resin 104 and a metal plate 112. After the heat conducting resin 102 is cured and the metal plate 112 and the lead frame 100 fixed with the light reflecting resin 104 are integrated, the light emitting element 108 and the reflecting ring 114 are mounted and then covered with the transparent resin 118. Thus, a light emitting module can be manufactured.

In addition, as the light reflecting resin 104, a white ceramic powder such as TiO ₂ or MgO, or a light reflecting powder having high light reflection such as glass powder or micro glass beads dispersed in a thermoplastic resin having high heat resistance. Can be used. Various members are commercially available for surface mounting LEDs, and such members can be used. In addition, as a method of molding such a commercially available light reflecting resin 104 with the lead frame 100, a material with high mass productivity such as injection molding can be selected. The light reflectance of the light reflecting resin 104 in the visible light region is desirably 90% or more and 99.9% or less. When the light reflectance is less than 90%, the reflection efficiency at the reflection ring 114 is affected. If the light reflectance is to be higher than 99.9%, the light reflecting resin 104 may be very expensive. The light reflecting resin 104 is preferably white. By making it white, color mixing of monochromatic light such as Red, Green, Blue, etc. is facilitated.

  Further, the light emitting element 108 is mounted on the lead frame within the area surrounded by the light reflecting resin 104, and further covered with the transparent resin 118 or the like, thereby protecting the light emitting element 108 and increasing the height of the plurality of light emitting elements 108. Density bear mounting is possible. In addition, by mounting a plurality of light emitting elements 108 at a high density, it becomes easy to uniformize white color due to color mixing.

  The light reflecting resin 104 can be injection molded using, for example, a polycarbonate resin in which a white pigment is dispersed. In particular, in the case of polycarbonate resin, it is desirable that the resin is sufficiently dried before injection molding. This is because the polycarbonate resin is a hydrophilic resin and absorbs moisture in the air. Therefore, if injection molding is performed without drying, a hydrolysis reaction of the resin may occur during molding, and the molecular weight of the resin may decrease, affecting the quality of the molded body. Therefore, the drying is desirably performed at 100 ° C. or higher (desirably performed at 110 ° C. to 130 ° C. for 4 to 6 hours). The molding temperature is preferably in the range of 250 ° C to 300 ° C, and the mold temperature is preferably in the range of 50 ° C to 120 ° C. If the temperature is lower than this range, the moldability may be affected. When the molding temperature is higher than this range, the moldability and the physical properties of the resin of the molded body may be affected.

In addition, PPS and liquid crystal polymer can be selected as the resin for the light reflecting resin 104. In the case of such a resin (for example, a liquid crystal polymer), the injection temperature is around 340 ° C. (desirably 270 ° C. or more and 380 ° C. or less. If the temperature range is lower than this temperature range, the injection moldability may be affected. May affect the resin). Similarly, the mold is heated to around 100 ° C. (preferably 50 ° C. or more and 130 ° C. or less, which may affect the moldability if it is lower than this temperature range. The same applies if it is higher than this temperature range). It is desirable to do. Examples of the white pigment to be added here may be used _{TiO 2, Al 2 O 3,} MgO or the like. The particle diameter of these pigments is preferably 10 microns or less and 0.01 microns or more (preferably 5 microns or less and 0.1 microns or more). If it is larger than 10 microns, the moldability may be affected. On the other hand, when the particle size is less than 0.01 micron, the specific surface area of the powder becomes too large, which may affect the fluidity during injection molding. Needless to say, the reflection ring 114 that can be retrofitted after the light emitting element 108 is mounted may be manufactured from the light reflecting resin 104 in addition to the insulating light reflecting material such as alumina.

  As described above, since the light emitting module according to the present invention can be used to stably light a large number of light emitting elements, in addition to backlights such as liquid crystal TVs, projectors, projectors, etc. It can also be applied to color rendering applications.

Top view and cross-sectional view illustrating a light-emitting module according to Embodiment 1 Diagram showing the shape of the lead frame Diagram showing how heat diffuses Sectional drawing which shows an example of the manufacturing method of the light emitting module in Embodiment 2. Sectional drawing which shows an example of the manufacturing method of the light emitting module in Embodiment 2. Reflective ring perspective view Sectional drawing which shows an example of the manufacturing method of the light emitting module in Embodiment 3. Sectional drawing which shows an example of the manufacturing method of the light emitting module in Embodiment 3. Sectional drawing which shows an example of the conventional light emitting module

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Lead frame 102 Thermal conductive resin 104 Light reflection resin 106 Auxiliary line 108 Light emitting element 110 Arrow 112 Metal plate 114 Reflection ring 116 Wall part 118 Transparent resin 120 Lens 122 Groove part 124 Projection part 126 Spacer part

Claims (18)

A lead frame mainly composed of copper fixed by a wall part of which is formed of a light reflecting resin;
A metal plate,
An insulating layer comprising a resin composition containing an inorganic filler and a thermosetting resin formed between the lead frame and the metal plate;
A reflection ring,
A light emitting module having a structure in which a part of a light emitting element mounted on the lead frame is reflected by the reflection ring. A lead frame mainly composed of copper, which is fixed by a wall part of which is made of light reflecting resin;
A metal plate,
An insulating layer comprising a resin composition containing an inorganic filler and a thermosetting resin formed between the lead frame and the metal plate;
With reflection ring,
The light emitting element mounted on the lead frame surrounded by the reflective ring, and the light emitting element,
A light emitting module having a structure in which a part of a transparent resin protecting a light emitting element mounted on the lead frame is accumulated in a gap between a reflection ring and the wall portion. 3. The light emitting module according to claim 1, wherein a thickness of the insulating layer formed between the metal plate and the lead frame is 50 μm or more and 500 μm or less. 3. The light emitting module according to claim 1, wherein the light reflecting resin has a light reflectance of 90% or more and 99.9% or less in a visible light region in which light reflecting powder is dispersed in the resin. The light emitting module according to claim 1, wherein the light emitting element is mounted on the lead frame within an area surrounded by the light reflecting resin and is further protected by the resin. The light emitting module according to claim 1, wherein a plurality of light emitting elements each having a different emission color are mounted in an area surrounded by a ring-shaped reflecting material. The light emitting module according to claim 1, wherein at least one of the plurality of light emitting elements has a white emission color. The light emitting module according to claim 1, wherein the lead frame has a thickness of 0.10 mm to 1.0 mm. The light emitting module according to claim 1, wherein the thermal conductivity of the insulating layer is 1 W / (m · K) or more and 20 W / (m · K) or less. _3. The light emitting module according to claim 1, wherein the inorganic filler includes at least one selected from the group consisting of Al ₂ O ₃ , MgO, BN, SiO ₂ , SiC, Si ₃ N ₄ , and AlN. The light emitting module according to claim 1, wherein the thermosetting resin includes 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 insulating layer is white. The light emitting module according to claim 1, wherein the reflective material is white. 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 light emitting module according to claim 1, wherein the light emitting module is used. 3. The light emitting module according to claim 1, wherein a part of the light reflecting resin is also formed at a gap between the lead frames and at a position between the lead frame and the insulating layer so as to avoid a position directly below the light emitting element. The light emitting module according to claim 1, wherein a part of the light reflecting resin forms a spacer that holds a gap between the lead frame and the metal plate. A lead frame partially fixed by a wall made of light reflecting resin;
Between metal plates,
In a state where the insulating resin is sandwiched, the insulating resin is cured,
After integrating the metal plate and the lead frame fixed with light reflecting resin,
A method for manufacturing a light emitting module on which the light emitting element and the reflective ring are mounted. A lead frame partially fixed by a wall made of light reflecting resin;
Between metal plates,
In a state where the insulating resin is sandwiched, the insulating resin is cured,
After integrating the metal plate and the lead frame fixed with light reflecting resin,
A method for manufacturing a light emitting module, wherein the light emitting element and the reflective ring are mounted and then covered with a transparent resin.

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