JP4408931B2 - Semiconductor light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor light-emitting device which has high radiation performance and is excellent in light-emitting efficiency and service life characteristic without deteriorating workability of a lead frame and reliability of an LED chip, in the semiconductor light-emitting device using a light-emitting element such as a light-emitting diode. <P>SOLUTION: The semiconductor light-emitting device includes the LED chip 4, a first lead frame 1 for mounting the LED chip 4, a second lead frame 2 to be electrically connected to the LED chip 4 via a bonding wire 5, epoxy resin 6 for sealing the LED chip 4, and a resin portion 3 for surrounding the epoxy resin 6 and fixing the first and second lead frames 1 and 2. The device has a ceramic body as a thermal conductor on the bottom of the first lead frame 1. The ceramic body is formed so as to extend to the lower part of a portion where the wire 5 in the second lead frame 2 is connected. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a semiconductor light emitting device, and more particularly to a semiconductor light emitting device using a light emitting element such as a light emitting diode (LED).

A typical semiconductor light emitting device has a structure as shown in FIG.
In FIG. 8, a resin portion 3 is formed by insert molding or the like so as to fix the first lead frame 1 and the second lead frame 2, and the LED chip 4 is formed on the first lead frame 1 by Ag paste 7. And a bonding wire 5 is attached to the second lead frame 2. The periphery of the LED chip 4 is protected and sealed with an epoxy resin 6.

Next, a method for manufacturing the semiconductor light emitting device of FIG. 8 will be described below.
First, the first lead frame 1 and the second lead frame 2 are formed in a specified pattern shape, and are insert-molded in the resin portion 3 in a state where bonding Ag plating is applied. Thereafter, the LED chip 4 is mounted on the first lead frame 1 with the Ag paste 7, and the bonding wire 5 is attached to the second lead frame 2, thereby electrically and mechanically connecting the lead frame, Seal with epoxy resin 6. Here, when the surface of the lead frame is Ag-plated, rust or the like is generated and the soldering is hindered. Therefore, exterior plating such as solder plating is applied to the lead frame portion. Then, unnecessary leads are cut, bent into a U-shape, and a terminal portion for joining to the mounting substrate is formed.

  By the way, heat is generated when the mounted LED chip emits light, but the amount of heat generated increases as the current flowing through the LED chip increases. In general, the higher the temperature of the LED chip, the lower the luminous efficiency of the LED chip, and the more the light deterioration becomes. That is, even if a large current is passed, it will not be bright effectively, and the life of the LED chip will be shortened.

  Therefore, by effectively releasing the heat generated from the LED chip to the outside and lowering the temperature, it is possible to provide an LED chip with good luminous efficiency and good life characteristics even at high currents.

  With respect to the conventional semiconductor light emitting device in which the heat dissipation effect is improved as described above, for example, JP-A-11-46018 (conventional example 1), JP-A-2002-222998 (conventional example 2), JP-A-2000-58924 (conventional example 3), JP-A 2000-77725 (conventional example 4), JP-A 2000-216443 (conventional example 5), and the like.

In the conventional example 1 and the conventional example 2, the surface area of the lead frame is increased, and in the conventional example 3, the conventional example 4 and the conventional example 5, the substrate is made of a metal having higher thermal conductivity than the resin. By doing so, heat dissipation is improved.
Japanese Patent Laid-Open No. 11-46018 JP 2002-222998 A JP 2000-58924 A JP 2000-77725 A JP 2000-216443 A

  However, even if the surface area of the lead frame on the LED element side is increased by making the shape of the lead frame non-linear or increasing the thickness as in Conventional Example 1 or Conventional Example 2, the package is limited. There is a limit in size, and the surface area of the lead frame cannot be sufficiently increased only by the shape change. Therefore, it is not possible to sufficiently improve the heat dissipation effect.

  In addition, since the lead frame is bent in a later process, the lead frame cannot be bent when it is thickened. Furthermore, as the thickness of the lead frame is increased, a larger force is required for punching the lead frame from the plate material as compared with a frame having a small thickness. For this reason, it is necessary to increase the thickness of the die in order to ensure the strength of the die, and the gap between the punched portions, that is, the lead frames is inevitably widened. (Generally, a gap equal to or more than about 3/4 of the thickness of the lead frame is required.) As a result of the wide gap between the lead frames, a bonding area cannot be secured or the frame area is small. Problem arises.

  As another measure for the above heat dissipation effect, there is a method of increasing the contact surface between the lead frame terminal on the LED element side and the mounting substrate, but although it is effective for heat dissipation, the heat at the time of soldering to the LED element It is easy to communicate and may adversely affect reliability.

  In addition, as in the conventional example 3, the conventional example 4 and the conventional example 5, when a metal having a higher thermal conductivity than the resin is used as the substrate, the reliability of the LED element is also affected by the heat during soldering as described above. May adversely affect sex.

  The present invention has been made in view of such circumstances, and does not reduce the workability of the lead frame and the reliability of the LED chip, and has a high heat dissipation property and good light emission efficiency and lifetime characteristics. The purpose is to provide.

A semiconductor light emitting device according to the present invention includes an LED chip, a first lead frame on which the LED chip is mounted, a second lead frame electrically connected to the LED chip via a wire, and a first lead frame. A ceramic body disposed at a lower portion of the LED, a first resin portion surrounding the periphery of the LED chip, and fixing the first and second lead frames, and an inner portion surrounded by the first resin portion. and a second resin portion, ceramic body is block-shaped, the lower portion, so as to contact with or close to the mounting substrate, exposed from the first resin portion, further, the ceramic body, the second lead The frame is formed so as to extend to a lower portion of a portion to which a wire is connected.

As described above, by having the ceramic body under the first lead frame, heat can be efficiently transferred from the first lead frame to the member, and a semiconductor light emitting device having excellent heat dissipation is provided. can do.

In the semiconductor light emitting device, preferably , the first lead frame and the second lead frame are in contact with the ceramic body .

According to the semiconductor light emitting device and its manufacturing method of the present invention, the heat generated in the LED chip, it is possible to heat radiation at the bottom of the ceramic body through with mounting substrate of the lead frame, there is no need to increase the thickness of the lead frame . Therefore, it is possible to prevent a decrease in workability of the lead frame. Further, heat during soldering is not easily transmitted to the LED. Therefore, it is possible to provide a semiconductor light emitting device with excellent heat dissipation without reducing the workability of the lead frame and the reliability of the LED chip.

  Embodiments of a semiconductor light emitting device and a method for manufacturing the same according to the present invention will be described below.

  First, an embodiment relating to the invention of a semiconductor light emitting device will be described with reference to FIGS.

  In the first to fifth embodiments described below, a plurality of LED chips 4 are preferably mounted. As a result, the applicability of the semiconductor light emitting device in this embodiment to a product such as full color display can be enhanced. When a plurality of LED chips are mounted in one product, the amount of heat generated is large, so heat dissipation becomes a very important problem, and thus a great effect can be expected in this embodiment.

FIG. 1 is a cross-sectional view of the surface-mounted LED in the first embodiment.
The semiconductor light emitting device in the present embodiment is electrically connected to the LED chip 4 via the LED chip 4, the first lead frame 1 on which the LED chip 4 is mounted, and a bonding wire 5 such as a gold wire. 2 and the resin part 3 which surrounds the periphery of the LED chip 4 and fixes the lead frame, and has a metal body 8 below the first lead frame 1.

  The first and second lead frames 1 and 2 are insert-molded in the resin portion 3. An LED chip 4 is mounted on the first lead frame 1 via an Ag paste 7, and a bonding wire 5 is attached to the second lead frame 2 so that the second lead frame 2 is connected to the LED chip 4. A resin portion 3 is formed so as to be mechanically and electrically connected and to surround the periphery. The inner side surrounded by the resin part 3 is sealed with an epoxy resin 6 in order to protect the LED element part.

  The metal body 8 is held by the resin portion 3 that functions as a substrate, and the lower portion thereof is exposed from the resin portion 3 so as to be close to or in contact with the mounting substrate. The metal body 8 has a block shape and is sandwiched between the first and second lead frames 1 and 2 via the resin portion 3.

  Here, it is preferable that the metal body 8 is separated from the first and second lead frames 1 and 2.

A gap is provided between the first and second lead frames 1 and 2 and the metal body 8 because the first and second lead frames 1 and 2 are separated from each other by contacting each other. This is to prevent the pattern from being short-circuited. In the present embodiment, the heat generated from the LED chip 4 is transmitted in the order of the first lead frame 1, the gap between the first lead frame 1 and the metal body 8, and the metal body 8, and is radiated to the mounting substrate. The In order to efficiently transmit the heat generated in the LED chip 4 to the metal body 8, the gap is preferably as small as possible. Further, it is preferable that the volume of the metal body 8 is as large as possible in the package.

  Here, it is preferable that the metal body 8 includes at least one material selected from the group consisting of Cu, aluminum, a Cu alloy, and an aluminum alloy. This is because the heat dissipation of these metals is high, so that the heat dissipation is further improved. However, in the sense that a material having a high heat dissipation is used as the metal body 8, other metal materials such as ceramics are used. There is no problem even if it is a material other than metal. When ceramic is used, the thermal conductivity is inferior to that of the metal material. However, since the ceramic material itself is insulative, the ceramic body in place of the metal body 8 can be replaced with the first and first ceramic bodies without performing insulation treatment on the surface. 2 lead frames 1 and 2 can be brought into contact with each other.

  The resin portion 3 located around the LED chip 4 uses a white resin having a high reflectivity in order to efficiently reflect the light emitted from the LED chip 4, and in order to efficiently emit the light to the front surface, The peripheral surface shape is molded to be, for example, an inverted conical shape. In addition, since the semiconductor light emitting device in the present embodiment is flowed to the subsequent process as a surface mounting component, a resin having excellent heat resistance is used for the resin portion 3. Specifically, for example, a liquid crystal polymer, a polyamide resin, or the like that satisfies both is used. When it is desired to increase the light emitting area, the inner peripheral surface shape of the resin part 3 may be a shape other than the inverted cone, for example, an inverted quadrangular pyramid shape.

  The epoxy resin 6 is a resin for protecting the LED element portion, and is mainly cast by a potting method, and a transparent or milky white resin is used. However, the epoxy resin 6 can also be formed by transfer molding, injection molding, or the like. In this case, it is possible to make the light emitting portion have an arbitrary shape (lens shape or the like).

  Here, since the metal body 8 is in the vicinity of the center of the resin portion 3 in a plan view, the metal body 8 is not directly subjected to heat at the time of soldering to the mounting board. Chip reliability is not reduced.

  In the present embodiment, with the above configuration and operation, the heat dissipation can be improved very simply as compared with the conventional semiconductor light emitting device.

FIG. 2 is a cross-sectional view of the surface-mounted LED in the second embodiment.
The semiconductor light emitting device in the present embodiment is one of the modifications of the semiconductor light emitting device in the first embodiment, and the metal body 8 is in contact with the first lead frame 1.

  For example, the first lead frame 1 on which the LED chip is mounted is made lower than the second lead frame 2 and brought into contact with the metal body 8. In the example of FIG. 2, the first lead frame 1 is bent and brought into contact with the metal body 8.

  Thereby, the heat generated from the LED chip 4 is transmitted in the order of the first lead frame 1, the metal body 8, and the mounting substrate. There is no portion corresponding to the gap between the first lead frame 1 and the metal body 8 in the first embodiment, and the heat generated in the LED chip 4 can be released to the mounting substrate more efficiently. In the present embodiment, the first lead frame 1 is lowered and brought into contact with the metal body 8. However, the first lead frame 1 is left as it is, and a convex portion is provided on the upper surface of the metal body 8. Even if the shape of the metal body 8 is changed, the same purpose can be achieved.

  In the present embodiment, the heat dissipation can be further improved by the above configuration and operation as compared with the first embodiment.

FIG. 3 is a cross-sectional view of the surface-mounted LED in the third embodiment.
The semiconductor light emitting device in the present embodiment is one example of a modification of the semiconductor light emitting device in the first embodiment. For example, an insulating film or the like is applied to the surface of the metal body 8 or an insulating paint is applied or anodized. An electrical insulation processing unit 9 is provided, and the surface of the metal body 8 subjected to the insulation treatment is in contact with the first and second lead frames 1 and 2.

  In the second embodiment, when there is only one LED chip 4 on the semiconductor light emitting device, or when there are a plurality of LED chips 4 on the same lead frame, heat generated from all the LED chips 4 is generated. In addition, it can be transmitted to the mounting substrate without passing through a portion corresponding to the gap between the first lead frame 1 and the metal body 8 in the first embodiment.

  However, when a plurality of LED chips 4 are present on different lead frames, only one of the lead frames is attached to the metal body 8 in order to prevent a pattern formed separately on each lead frame from short-circuiting. As a result, a pattern portion in which improvement in heat dissipation is limited is generated.

  Although the intended purpose of the present embodiment is the same as that of the second embodiment, all the lead frame patterns are in contact with the metal body 8 by providing the metal body 8 with the electrical insulation processing portion 9. However, it is different in that all the pattern portions can have a high heat dissipation effect without being short-circuited.

  In the present embodiment, even when a plurality of LED chips 4 are present on different lead frames, the heat dissipation can be easily improved, and the heat generated from the LED chips 4 is generated by the first lead frame 1 and the metal. In addition to the route of the body 8 and the mounting board in this order, it is also possible to expect the effect that the heat that has entered the metal body 8 is further released to the mounting board through the second lead frame 2.

FIG. 4 is a cross-sectional view of the surface-mounted LED in the fourth embodiment.
The semiconductor light emitting device in the present embodiment includes an LED chip 4, a metal body 8 on which the LED chip 4 is mounted, a first lead frame 1 electrically connected to the metal body 8, and a bonding wire 5. It has the 2nd lead frame 2 electrically connected with an LED chip, and the resin part 3 which surrounds the circumference | surroundings of the metal body 8 and the LED chip 4, and fixes a 1st and 2nd lead frame.

  In the present embodiment, since the LED chip 4 is mounted directly on the metal body 8, the heat generated from the LED chip 4 is directly transmitted to the metal body 8 and is transmitted to the mounting substrate via the metal body 8. Therefore, heat can be released more efficiently than the first to third embodiments.

FIG. 5 is a cross-sectional view of the surface-mounted LED in the fifth embodiment.
In the present embodiment, the top portion of the metal body 8 is processed into an inverted conical shape, and the top portion is fitted into the first lead frame 1. Further, the metal body 8 and the first lead frame 1 are caulked to be integrated, and at the same time as the caulking process, the top of the metal body 8 is processed into an inverted conical shape. Thereby, the metal body 8 and the first lead frame 1 are firmly fixed. Further, the luminous intensity of the semiconductor light emitting device can be increased by the inverted conical reflection effect. Note that the shape of the top of the metal body 8 may be a shape other than the above-described inverted cone, for example, an inverted quadrangular pyramid.

  Next, an embodiment relating to the fixing of the metal body 8 to the resin portion 3 will be described with reference to FIGS. 6 and 7.

  6 (a) and 6 (b) are diagrams showing a method of manufacturing a substrate on which the LED according to the sixth embodiment is mounted.

  In the present embodiment, the method for manufacturing the substrate on which the LED is mounted includes the step of forming the metal part 8 as the metal body and the resin part 3 holding the lead frame 10 by insert molding, the metal body 8 or the lead. A step of mounting the LED chip 4 on the frame 10 is provided. 6A and 6B show an example in which the LED chip 4 is mounted on the lead frame 10.

  As shown in FIG. 6A, the lead frame 10 and the metal body 8 are set almost simultaneously in the insert molding die 11 and insert molding is performed. Thereby, as shown in FIG. 6B, the resin portion 3 can be formed so that the lead frame 10 and the metal body 8 are integrated. Thereafter, the LED chip 4 is mounted on one lead frame 10 using Ag paste, and the other lead frame and the LED chip 4 are connected via bonding wires.

FIG. 7 is a diagram showing a method for manufacturing a substrate on which an LED is mounted in the seventh embodiment.
In the present embodiment, the method of manufacturing the substrate on which the LED is mounted includes the step of holding the lead frame 10 and forming the resin portion 3 having the recess 13 by insert molding, and the metal body 8 as a metal body in the recess 13. And a step of mounting the LED chip 4 on the metal body 8 or the lead frame 10.

  As shown in FIG. 7A, a lead frame 10 is set in an insert molding die 11 having a metal body insertion portion forming die 12, and insert molding is performed. Thereby, as shown in FIG. 7B, the resin portion 3 that holds the lead frame 10 and has the recess 13 can be formed. Next, as shown in FIG.7 (c), the metal body 8 is inserted in the recessed part 13 in the resin part 3 after the said shaping | molding, and it fixes using an adhesive agent. Thereafter, through the same process as in the sixth embodiment, the LED chip 4 is mounted on one lead frame, and the other lead frame and the LED chip 4 are connected via a bonding wire.

  Although the embodiments of the present invention have been described above, the embodiments disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is sectional drawing of the surface mount type LED which concerns on Embodiment 1 of this invention. It is sectional drawing of surface mount type LED which concerns on Embodiment 2 of this invention. It is sectional drawing of surface mount type LED which concerns on Embodiment 3 of this invention. It is sectional drawing of surface mount type LED which concerns on Embodiment 4 of this invention. It is sectional drawing of surface mount type LED which concerns on Embodiment 5 of this invention. It is the figure which showed the manufacturing method of the board | substrate which mounts LED in Embodiment 6 of this invention, (a) is the figure which set the lead frame and the metal body to the insert molding die, (b) is the lead frame. It is a figure which shows the resin part after the insert molding of a metal body is completed. It is the figure which showed the manufacturing method of the board | substrate which mounts LED in Embodiment 7 of this invention, (a) is the figure which set the lead frame to the insert molding metal mold | die, (b) is the insert molding of a lead frame. It is a figure which shows the resin part after completion | finish, and (c) is a figure which shows the state which inserted the metal body in the recessed part of the resin part. It is sectional drawing of the conventional typical semiconductor light-emitting device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 1st lead frame, 2nd 2nd lead frame, 3 resin part, 4 LED chip, 5 bonding wire, 6 epoxy resin, 7 Ag paste, 8 metal body, 9 electrical insulation processing part, 10 lead frame, 11 Insert molding die, 12 metal body insertion part forming die, 13 recess.

Claims (2)

An LED chip;
A first lead frame on which the LED chip is mounted;
A second lead frame electrically connected to the LED chip via a wire ;
A ceramic body disposed under the first lead frame;
Said LED surrounds the chip, the first and second lead frames solid was constant, the first resin portion formed so as to hold the ceramic body,
A second resin portion for sealing an inner side surrounded by the first resin portion ,
Before Symbol ceramic body is block-shaped, the lower portion, so as to contact with or close to the mounting substrate, exposed from the first resin section,
Furthermore, the ceramic body is formed to extend to a lower portion of a portion to which the wire is connected in the second lead frame.   The semiconductor light emitting device according to claim 1, wherein the first lead frame and the second lead frame are in contact with the ceramic body.

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