JP2007266246A - Led module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface mounting LED module excellent in heat radiation characteristics of which the heat from an LED element is efficiently radiated to the outside. <P>SOLUTION: The LED module comprises an LED element 3, a stage 2 having a fitting surface at its upper part on which the LED element 3 is attached by flip chip mounting or face-up mounting, and a sealing member 6 of translucent resin or glass in which the LED element 3 is arranged on the stage 2, with the profile of the surface contacting the stage 2 being larger than that of the lower part of the stage 2. The heat from the LED element 3 is radiated from the side surface of the stage 2 made from ceramics or resin, and the heat from the LED element 3 is radiated from the outer surface of the sealing member 6 that seals the LED element 3. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a structure for radiating heat from a semiconductor light emitting device provided in an LED module.

  Conventional semiconductor light emitting devices (hereinafter referred to as LED devices) have been used in display devices and lighting application devices that can function even with relatively small light output. In recent years, semiconductor light emission with a large light output has appeared, and its application products are increasing.

  However, since the heat generated from the LED element increases as the light output increases, it is necessary to dissipate the heat generated from the LED element.

  The heat generated from the LED element increases the temperature of the LED element itself, and further increases the temperature of the sealing resin around the LED element. The lifetime of the LED element and the sealing resin decreases as the temperature rises.

  Therefore, as heat dissipation of the LED element and the sealing resin, the surface-mounted LED element covers the light emitting element chip, the base on which the light emitting element chip is arranged, the lead frame connected to the LED element chip, and at least the LED element chip. A surface mount type light emitting device in which the base and the lead frame are integrally fixed with the sealing resin, and in particular, the bottom surface of the base viewed from the front side is displayed. The distance between the LED element chip and the base is located on the same surface as the bottom surface of the lead frame viewed from the surface side, and the bottom surface of the base viewed from the surface side is exposed from the sealing resin. Therefore, the heat dissipation to the substrate of the LED element chip can be improved (for example, Patent Document 1).

JP 2002-252373 A (paragraph “0017”, lines 11 to 15)

  However, since the entire LED module is covered with a transparent resin, it is not optimal to dissipate heat outward from a base made of a material having excellent thermal conductivity. It is an object of the present invention to provide a surface mount type LED module having excellent heat dissipation that efficiently dissipates heat from LED elements arranged on a base made of ceramics or resin.

  An LED element, a base having an attachment surface to which the LED element is attached by flip-chip mounting or face-up mounting on the upper side, and an LED element provided on the upper part of the base to seal the LED element, and in contact with the base And a sealing member made of a light-transmitting resin or light-transmitting glass whose outer shape is larger than that of the lower portion of the base.

  The heat from the LED element can be radiated from the side surface of the base made of ceramic or resin, and the heat from the LED element can be radiated from the outer surface of the sealing material for sealing the LED element.

Embodiment 1 FIG.
FIG. 1 is a perspective view of the LED module showing the first embodiment, and FIG. 2 is a cross-sectional view of the LED module of FIG.

The structure of the LED module shown in FIGS. 1 and 2 will be described.
FIG. 1 shows a mortar-shaped base 2 formed of ceramics or a resin material and having a recess on the upper surface, an LED element 3 attached to the recess of the base 2, and the LED element 3 is sealed to the base 2. The LED module 1 includes a sealing material 6.

  FIG. 2 is a cross-sectional view of the LED module 1 taken along the line AA in FIG. 1, and wiring is drawn from the bottom of the base 2 of the LED module 1 to the inside of the recess, and inside the bottom of the base 2 and the inside of the recess. Electrical circuits 5a and 5b having electrodes 4a to 4d are provided, and the LED element 3 is mounted on the electrodes 4a and 4b inside the recess by flip chip mounting or face-up mounting, and is electrically connected to the electrical circuits 5a and 5b. Yes.

  Here, the flip chip mounting means that when the LED element 3 is mounted in the concave portion of the base 2, the electrode (not shown) of the LED element 3 is directly mounted on the electrodes 4a and 4b by soldering or the like. The sapphire surface of the element 3 is arranged on the light emitting surface side of the LED module 1.

  The face-up mounting means mounting a sapphire surface (die bonding) when mounting the LED element 3 on the concave portion 2 of the base 2 of the LED element 3, and connecting the electrodes (not shown) of the LED element 3 to the electrodes 4a and 4b. Wiring (wire bonding) is performed using a gold wire (Au wire) or the like, and the sapphire surface of the LED element 3 is disposed on the electrode 4a, 4b side of the recess.

  Further, a sealing material 6 such as transparent resin or transparent glass is provided on the upper portion of the base 2 so as to cover the LED element 3. The sealing material 6 has a concave portion of the base 2 and a protruding portion that seals the LED element 3, and a mushroom shape formed so as to protrude outward from the outer edge of the base 2. It has become. The contact surface of the sealing material 6 with the base 2 is in close contact with the inside of the recess of the base 2 and the surface of the LED element 3.

  The sealing material 6 encloses a phosphor (not shown) that emits light when excited by the light emitted from the LED element 3. For example, when the light emitted from the LED element 3 is blue, it is complementary to blue. A phosphor that emits yellow light in a related relationship is enclosed, and white is obtained by mixing the light emitted from the LED element 3 and the light excited by the phosphor.

  In addition, when it is desired to obtain the light emission color itself emitted from the LED element 3 such as red, green, and blue, or when the light emission color emitted from the LED element 3 is mixed, it is necessary to encapsulate the phosphor in the sealing material 6. There is no.

Next, the flow of heat due to the heat generated by the LED element 3 will be described.
The heat generated by the LED element 3 is broadly divided and dissipated outward through three paths.

  The first heat conduction path is conducted from the LED element 3 to the substrate (not shown) on which the LED module 1 is mounted via the electric paths 5a and 5b. In this way, the heat generated by the LED element 3 is conducted to the substrate and diffused outward from the substrate.

  In the second heat conduction path, heat generated from the LED element 3 is transferred from the contact surface between the LED element 3 and the sealing material 6 to the sealing material 6, and heat radiation and air are transmitted from the outer surface of the sealing material 6. Dissipates outward by convection.

  Since the sealing material 6 of this embodiment is located above the base 2 and the outer wall of the base 2 is not covered with the sealing material 6 and exposed, the heat dissipation effect by the above-described second heat conduction path is obtained. Rise.

  That is, since the side surface of the base 2 is not covered with the sealing material 6 in the second heat conduction path, it is generally from the side surface of the base 2 that is formed of a material having high thermal conductivity and high surface emissivity. The efficiency of heat dissipation by heat radiation and air convection is improved.

  The third heat conduction path is such that the heat generated by the LED element 3 is conducted from the contact surface between the LED element 3 and the encapsulant 6 to the encapsulant 6, and the heat conducted to the encapsulant 6 is the base. Heat is transferred from the contact surface with 2 to the base 2. The heat transferred to the base 2 is dissipated outward from the outer surface of the base 2 by heat radiation and air convection.

  The sealing material 6 of this embodiment is formed above the base 2 so as to project outward from the outer edge of the base 2 so that the outer surface of the sealing material 6 becomes large. Therefore, the heat dissipation effect by the third heat conduction path described above is enhanced.

  That is, since the surface area of the sealing material 6 is large in the third heat conduction path, the heat dissipation due to the convection of the heat radiation in which the size of the heat flow is determined in proportion to the surface area becomes large.

  As described above, the LED element 3, the base 2 having an attachment surface to which the LED element 3 is attached by die bonding and wire bonding, and the sealing material 6 made of transparent resin or transparent glass are attached to the attachment surface of the base 2. And the sealing material 6 that seals the LED element 3 so that the size of the surface in contact with the base 2 is larger than the area of the mounting surface of the base 2. 2 can improve heat dissipation from the outer surface of the sealing member 6 and can improve heat dissipation from the surface area of the sealing material 6.

Embodiment 2. FIG.
In the present embodiment, the shape of the sealing material 6 of the LED module 1 shown in the first embodiment is changed.

  FIG. 3 is a cross-sectional view of the LED module showing the second embodiment. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

The structure of the LED module of FIG. 3 will be described.
In FIG. 3, the shape of the sealing material 6a covering the LED element 3 is a mushroom shape, and a satin-like uneven portion is formed on the outer surface of the mushroom-shaped bulk portion.

  In this way, the surface area is increased by providing an uneven portion on the outer surface of the sealing material 6a, the contact surface between the surface of the sealing material 6a and the air layer is increased, and heat is efficiently radiated to the air layer.

FIG. 4 is a diagram illustrating diffusion of light emitted from the LED element 3 according to the second embodiment.
The diffusion of light emitted from the LED element 3 in the LED module of FIG. 4 will be described.

  The LED element 3 emits light when power is supplied from the electrodes 4a and 4b. The emitted lights 7a and 7b are generally refracted on the outer surface of the sealing material 6 because the relationship between the refractive index N1 of the sealing material 6 and the refractive index N2 in the air is N1> N2.

First, the light 7a emitted from the LED element 3 will be described.
The refraction of the light 7 a emitted from the LED element 3 is as follows: the perpendicular A on the outer surface A surface of the sealing material 6, the incident angle θ <b> 1 a with respect to the perpendicular A when incident on the outer surface A surface of the sealing material 6 When the emission angle θ2a with respect to the perpendicular A when emitted from the air into the air, the relationship is N1 · sin θ1a = N2 · sin θ2a.

  Therefore, the light 7a emitted from the LED element 3 is incident at an incident angle θ1a from the central direction of the LED module 1 when the perpendicular line A of the outer surface A surface is used as an axis. The module 1 is refracted at the emission angle θ2a in the side surface direction (A direction).

Next, the light 7b emitted from the LED element 3 will be described.
The refraction of the light 7b emitted from the LED element 3 has the same relationship as that of the light 7a emitted from the LED element 3, and the relationship is N1 · sin θ1b = N2 · sin θ2b (perpendicular B, incident angle θ1b to perpendicular B, perpendicular The emission angle with respect to B is θ2b).

  Therefore, the light 7b emitted from the LED element 3 is incident at an incident angle θ1b from the side surface direction of the LED module 1 when the vertical line B of the outer surface B surface is used as an axis. The light is refracted at the emission angle θ2b in the front direction (B direction) of the module 1.

  That is, by attaching a concavo-convex portion to the outer surface of the sealing material 6a, even if the LED element 3 having a strong directivity is used, depending on the incident angle and refractive index to the concavo-convex portion on the outer surface of the sealing material 6a. Since the lights 7a and 7b are refracted, the light obtained from the outer surface of the sealing material 6a is diffused, and diffused light having a weak directivity of the light emitted from the LED element 3 can be obtained.

  Thus, since the outer surface of the sealing material 6a is provided with a satin-like uneven portion, the contact surface between the sealing material 6a and the air layer can be increased to efficiently dissipate the LED element 3, and the matte surface. The light emitted from the LED element 3 can be diffused by the uneven portions.

  In addition, a rectangular shape etc. may be sufficient instead of the matte-like uneven | corrugated | grooved part of the outer surface of the sealing material 6a.

Embodiment 3 FIG.
In the present embodiment, the shape of the base of the LED module shown in the first embodiment is changed.

  FIG. 5 is a cross-sectional view of the LED module showing the third embodiment, and FIG. 6 is a cross-sectional view of another LED module showing the third embodiment. The same parts as those in the first embodiment are denoted by the same reference numerals. The description is omitted.

The structure of the LED module of FIG. 5 will be described.
In FIG. 5, a projecting portion 8 that extends outward and horizontally from the upper side surface of the base 2 is provided, and the upper surface of the base 2 projects outward from the bottom of the base 2. The sealing material 6 is brought into contact with the upper surface of the protruding portion 8.

  As described above, since the overhanging portion 8 extending from the side surface on the upper side of the base 2 to the outside and in the horizontal direction is provided, the base 2 that is generally formed of a material having high thermal conductivity and high surface emissivity. The surface area is increased, and the efficiency of heat dissipation by heat radiation from the base 2 and air convection is improved.

  Further, as shown in FIG. 6, the outer diameter of the upper side of the base 2 is increased and the outer diameter of the lower side is decreased, instead of the overhanging portion 8 extending outward and horizontally from the upper side surface of the base 2. Then, the entire side surface may be narrowed from the upper part toward the lower part.

Embodiment 4 FIG.
In the present embodiment, the shape of the base 2 of the LED module shown in the first embodiment is changed.

  FIG. 7 is a cross-sectional view of the LED module showing the fourth embodiment, and FIG. 8 is a cross-sectional view of another LED module showing the fourth embodiment, which is the same as in the first to third embodiments. Are denoted by the same reference numerals, and description thereof is omitted.

The structure of the LED module of FIG. 7 will be described.
FIG. 7 shows that the reflective layer 9 is formed by vapor-depositing light reflecting members (for example, aluminum and silver) on the surface of the mortar portion of the base 2 and the overhanging portion 8 extending outward from the upper end of the base 2. is doing.

  As shown in FIG. 7, by providing the reflective layer 9 in the recess of the base 2, the light emitted from the LED element 3 strikes the reflective layer and is reflected to the outside of the base 2. It is clear that the loss of light due to reflection decreases as the reflective layer has a higher reflectivity.

  Therefore, by providing a reflective layer in the concave portion and the overhanging portion 8 of the base 2, the light extraction efficiency obtained by irradiating the light emitted from the LED element 3 from the sealing material 6 to the outside increases.

  Further, as shown in FIG. 8, when the reflective layer 9 is formed on the upper surface of the base 2 and a satin-like uneven portion is attached to the outer surface of the sealing material 6 a made of transparent sealing resin or transparent sealing glass, Since the light emitted from the LED element 3 is reflected by the reflective layer 9, the extraction efficiency of the light obtained by irradiating the sealing material 6a to the outside increases, and the incident angle of the concavo-convex portion on the outer surface of the sealing material 6a and Due to the refractive index, the light from the LED element 3 is refracted, and diffused light in which the directivity of the light emitted from the LED element 3 is weakened can be obtained.

Embodiment 5 FIG.
In the present embodiment, the shape of the base 2 of the LED module 1 shown in the first embodiment is changed.

  FIG. 9 is a cross-sectional view of the LED module showing the fifth embodiment. The same parts as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

The structure of the LED module of FIG. 9 will be described.
The flat base 2a is provided with electrodes 4a and 4b, and the LED element 3 is mounted on the electrodes 4a and 4b by die bonding and wire bonding.

  The sealing material 6b is attached to the upper part of the LED element 3, the phosphor 10 is sealed in the vicinity of the LED element 3, the light emitted from the LED element 3 is irradiated, and the phosphor 10 is excited to emit light.

  Since the light emitted from the LED element 3 is emitted from the PN junction surface, the light emitted toward the side surface of the LED element 3 is strong.

  Therefore, when it is desired to obtain light from the LED module 1 in the lateral direction, a desired light output can be obtained by making the base 2a flat.

  Moreover, the light emitted from the LED element 3 can be diffused by enclosing a diffusion material such as titanium oxide in the sealing material 6b or by sandblasting the outer surface of the sealing material 6b to provide fine irregularities. .

  The present invention relates to a heat dissipation structure for LED elements in an LED module.

1 is a perspective view of an LED module showing Embodiment 1. FIG. It is AA sectional drawing of the LED module shown in FIG. FIG. 6 is a cross-sectional view of an LED module showing a second embodiment. FIG. 10 is a diagram showing light diffusion of the LED element of the second embodiment. FIG. 5 is a cross-sectional view of an LED module showing a third embodiment. It is sectional drawing of the LED module which shows other Embodiment 3. FIG. FIG. 6 is a cross-sectional view of an LED module showing a fourth embodiment. It is sectional drawing of the LED module which shows other Embodiment 4. FIG. FIG. 6 is a cross-sectional view of an LED module showing a fifth embodiment.

Explanation of symbols

  1 LED module, 2, 2a base, 3 LED element, 4a, 4b, 4c, 4d electrode, 5a, 5b electric circuit, 6, 6a, 6b sealing material, 7a, 7b Light emitted from LED element 3, N1 sealing Refractive index of stopper 6, N2 refractive index in air, incident angle with respect to θ1a A surface, incident angle with respect to θ1b B surface, outgoing angle with respect to θ2a A surface, outgoing angle with respect to θ2b B surface, 8 overhanging portion, 9 reflecting layer, 10 Phosphor.

Claims (6)

An LED element;
A base having a mounting surface on the LED element mounted thereon by flip-chip mounting or face-up mounting;
A sealing member made of a light-transmitting resin or light-transmitting glass, wherein the LED element is disposed on the upper portion of the base and the outer shape of the surface in contact with the base is larger than the outer shape of the lower portion of the base When,
An LED module comprising: The base is provided with a concave portion in the upper part having a mortar cross-sectional shape,
The LED module according to claim 1, wherein the sealing member includes a convex portion that contacts the concave portion.   The LED module according to claim 1, wherein the base includes an overhanging portion that protrudes outward and horizontally from the upper end surface.   3. The LED module according to claim 1, wherein the base is formed in a substantially inclined surface shape so that a shape of a side surface is narrowed from the upper part of the base toward the lower part. 4.   The LED module according to claim 3, wherein the sealing member covers a surface of the base on the upper side.   The LED module according to claim 1, wherein the LED module of the sealing member has an uneven portion on an outer surface that transmits light emitted from the LED element and outputs light to the outside.

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