JP2007096108A - Light emitting device and its fabrication process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting device applicable as an edge emission light source in which deterioration of a sealing member can be prevented by attaining good heat dissipation properties. <P>SOLUTION: The light emitting device comprises a metal case 2 having a containing space 2A spreading from bottom face side of a case toward the light exit side and lead insertion holes 2B and 2C communicating with the containing space 2A, an LED element 3 mounted on the bottom face of the metal case 2 and sealed with a sealing member 9, leads 4 and 5 for external connection connected with the LED element 3 and led out from the lead insertion holes 2B and 2C to the outside of the metal case 2, and an insulating resin package 6 covering the metal case 2 to expose a part thereof to the outside and securing the leads 4 and 5 for external connection to the metal case 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light-emitting device that can effectively dissipate heat generated by a light-emitting element due to high output and a method for manufacturing the same.

  In recent years, development of high-power LED (Light Emitting Diode) elements has been promoted, and a large-output type of several watts has already been commercialized. The LED element is characterized by low heat generation. However, since a high current (high luminance) type LED element flows a large current, a non-negligible level of heat generation occurs.

  For example, an LED (light emitting device) package (resin case) using a lead frame is formed by fixing the lead frame to an injection mold, and then pouring a molten thermoplastic resin, followed by cooling and solidification. Is done by doing. There are mainly the following four functions of the resin case. (1) Mechanically fixing the lead frame, (2) Insulating the leads and the LED external part, and (3) Functioning as a reflector for emitting light emission from the LED in a specific direction. (4) The liquid sealing material is fastened in the case. There is a light emitting device in which this resin occupies the main part of the structure and the efficiency of extracting light from the LED package is increased by using a highly reflective resin such as a white resin.

  Side light-emitting LED devices used as light sources for liquid crystal displays in mobile phones are required to be thin along with side light-incident light guide plates. Thinning the LED device results in a thin resin case, and no matter how highly reflective resin is used as the material of the resin case, the amount of leakage light increases, and the amount of light in a predetermined emission direction is reduced. Decrease. Moreover, if the material of the case is a thermoplastic resin and its thickness is thin, it may be deformed during solder mounting. Under conditions of high temperature and high light output, material deterioration will occur and the life will be affected.

  A power semiconductor / transistor generally uses a metal heat sink fixed with a resin as a heat radiating member, and releases heat generated from the semiconductor through the metal heat sink. In this case, a thermosetting resin is often used as the resin, and the resin is molded by a method represented by transfer molding. As the color tone, there are generally many black to gray colors, and therefore the light reflectance is low, and it cannot be used as a reflection member of an LED. There is an example in which an LED is configured by using a lead frame of a power semiconductor, but in general, the lifetime cannot be denied due to the deterioration of the resin as described above.

  On the other hand, in the resin case, after the LED element is mounted on the bottom surface, the resin case is sealed with a translucent resin mixed with a fluorescent material, a diffusing material, and the like. In this case, the sealing resin (translucent resin) consists of a resin case (organic material / linear expansion coefficient / insulator) and a metal frame (inorganic material) formed of materials having different properties (thermoplastic resin and metal). -It must adhere and adhere well to both of the low linear expansion coefficient and conductor. In addition, performance must be maintained over a wide temperature range (-40 ° C to 270 ° C). When these conditions are not satisfied, there is a high possibility that the disconnection / optical performance deteriorates due to peeling of the sealing member.

  As described above, it is extremely difficult to reduce the height (thickness) of a side-emitting LED device having a good reflecting function and using a thermoplastic resin as a case material, and this can be realized temporarily. However, it is necessary to sacrifice a large part of the performance.

  Conventionally, as a light emitting device capable of effectively dissipating heat generated by a light emitting element due to high output, a copper metal base portion functioning as a heat radiator and mounted on this metal base portion via a submount The thing provided with the LED element and the sealing member which seals this LED element is proposed (for example, patent documents 1).

In addition, the conventional light emitting device includes a metal stem having a recess, an LED element mounted on the bottom surface of the recess of the stem, and a sealing member that seals the LED element and a part of the stem. The thing is adopted. This stem type light emitting device is currently used for laser diodes that require heat dissipation, but has been widely used for transistor packages and the like.
JP 2005-116990 A

  However, according to the LED device described in Patent Document 1, since the LED element is mounted on the submount located on the bottom surface of the recess formed on the metal base portion, the metal base portion functions sufficiently as a heat sink. As a result, there is a disadvantage that the sealing resin in the recess is deteriorated.

  In addition, according to the LED device in which the LED element is mounted on the bottom surface of the concave portion of the metal stem, the stem volume cannot be increased and the stem is provided at one end of the lead, so that the stem functions sufficiently as a heat sink. Moreover, since the said recessed part is deep, there exists a problem which cannot be utilized for side surface light emission.

  Accordingly, an object of the present invention is to provide a light emitting device that can obtain good heat dissipation and prevent deterioration of a sealing member, and can be used as a light source for side light emission, and a method for manufacturing the same. is there.

(1) In order to achieve the above object, the present invention forms a concave element housing space having an element mounting area for mounting a light emitting element on the bottom surface, and penetrates the metal case in the vicinity of the element mounting area. A metal case having a pair of lead insertion holes communicating with the element receiving space, a pair of leads fixed to the pair of lead insertion holes via insulating members, and the element mounting region. A light-emitting element mounted and connected to the pair of leads via a bonding wire; a sealing member that fills the element housing space and seals the light-emitting element; and the other end of the pair of leads Provided is a light emitting device comprising a package member exposed to the outside and embedded with the metal case and the pair of leads.

(2) In order to achieve the above object, the present invention provides a metal case having a housing space that expands from the case bottom side toward the light extraction side and a lead insertion hole that communicates with the housing space, and a bottom surface of the metal case. A light emitting device mounted and sealed by a sealing member; an external connection lead connected to the light emitting device and led out of the metal case from the lead insertion hole; and the metal case. And a package made of an insulating resin for fixing the external connection lead to the metal case, the case frame serving as the metal case. A first step of assembling the lead frame as a lead for external connection and a lead frame which are not in contact with each other and holding the lead frame in a package molding die, and the package To provide a method of manufacturing a light emitting device which comprises a second step of forming the package by injecting an insulating resin into the shape mold.

  According to the present invention, it is possible to obtain good heat dissipation and prevent deterioration of the sealing member, and it can be used as a light source for side light emission.

[First embodiment]
FIG. 1 is a diagram for explaining a light emitting device according to a first embodiment of the present invention. 1 (a) is a front view, FIG. 1 (b) is a plan view, FIG. 1 (c) is a side view, and FIG. 1 (d) is an AA cross-sectional view of FIG. 1 (b). FIG. 2 is an enlarged front view showing the main part of FIG. FIG. 3 is a diagram schematically showing a mounting state of the light emitting device according to the first embodiment of the present invention on a circuit board. 3A is a plan view, and FIG. 3B is a cross-sectional view.

[Overall configuration of light emitting device]
In FIG. 1, a light emitting device denoted by reference numeral 1 includes a metal case 2 with a heat dissipation function, an LED element 3 as a light emitting element, and a pair of external connection leads 4 for supplying power to the LED element 3. 5 and a package 6 for fixing the pair of external connection leads 4, 5 to the metal case 2. Then, as shown in FIGS. 3A and 3B, the circuit board 7 is mounted on the wiring pattern 7 </ b> A via the solder 8. In FIGS. 3A and 3B, reference numeral 7B denotes a resist pattern of the circuit board 7.

(Configuration of metal case 2)
The metal case 2 has a substantially truncated quadrangular pyramid-shaped accommodation space 2A that extends from the case bottom side toward the light extraction side, and lead insertion holes 2B and 2C that communicate with the accommodation space 2A. It is formed by a box. A rectangular opening 2a is provided as a light outlet on the light extraction side of the housing space 2A. The lead insertion holes 2 </ b> B and 2 </ b> C are arranged on the bottom surface of the metal case 2. As a material of the metal case 2, a heat conductive material such as copper (Cu) or aluminum (Al) is used. The height dimension of the metal case 2 is set to 0.8 mm, for example.

  As shown in FIG. 2, the inner surface of the metal case 2 is subjected to a metal plating treatment of aluminum (Al) or silver (Ag), thereby reflecting the light emitted from the LED element 3 in the light extraction direction. The surfaces 2D to 2H are formed. The light reflecting surface 2D is a surface parallel to the opening surface of the metal case 2, and the light reflecting surfaces 2E to 2H are inclined surfaces (an inclined surface with the light reflecting surface 2D as a reference surface). The inclination angles of the light reflecting surfaces 2E and 2F are set to be smaller than the inclination angles of the light reflecting surfaces 2G and 2H. The metal case 2 is integrally provided with heat-dissipating ribs 2I and 2J so that the end portions of the ribs are exposed outside the package 6 together with the case opening end surface and the case side surface (long side surface).

  The ribs 2I and 2J are formed by embedding a base end portion (intermediate portion) in the package 6 by insert molding and punching and pressing a case frame made of copper (Cu) as a whole. The ribs 2I and 2J are provided with through holes 2d and 2d as shown in FIG. Thereby, a part of the package 6 is filled in the through holes 2d and 2d when the package is formed, and good adhesion of the ribs 2I and 2J to the package 6 is obtained. As shown in FIG. 1A, the end surfaces on one end of the ribs 2I and 2J are arranged at positions spaced apart from the side surfaces of the lower end of the package 6 with a gap G. As a result, fillets are formed at the tips of the ribs 2I and 2J at the time of solder mounting, and the reliability of the light emitting device 1 at the time of solder mounting is improved. In addition, it is possible to obtain a self-alignment function that automatically corrects the positional deviation of the light emitting device 1 during solder mounting due to the surface tension of the molten solder.

(Configuration of LED element 3)
The LED element 3 is a high-power / face-up (FU) type blue LED element formed using a semiconductor material such as GaN or AlInGaP, and is housed in the housing space 2A and out of the light reflecting surfaces 2D to 2H. It is mounted on the light reflecting surface 2D (case bottom surface). The LED element 3 is sealed together with a bonding wire 10 such as gold (Au) by a sealing member 9 in the accommodation space 2A. The planar size of the LED element 3 is set to a dimension of about 0.3 × 0.3 mm, for example.

  The sealing member 9 is made of a synthetic resin material such as silicone or epoxy resin. The sealing member 9 contains a phosphor such as YAG (Yttrium Aluminum Garnet) that emits wavelength-converted light (yellow light) when excited by receiving the emitted light (blue light) from the LED element 3. .

(Configuration of external connection leads 4 and 5)
As shown in FIGS. 1B and 1C, most of the external connection leads 4 and 5 are embedded in the package 6 by insert molding like the ribs 2I and 2J. It is led out of the metal case 2 from the holes 4 and 5, and the whole is formed by punching and pressing a lead frame made of copper (Cu). The external connection leads 4 and 5 are formed of bent pieces having a substantially Z-shaped bent portion as shown in FIG. As a result, the movement of the external connection leads 4 and 5 with respect to the package 6 is restricted, and the disconnection of the bonding wire 10 is prevented.

  An insulating member 11 such as an epoxy resin is interposed between the element connection side ends of the external connection leads 4 and 5 and the inner surfaces of the lead insertion holes 2B and 2C. The front ends of the external connection leads 4 and 5 are exposed outside the package 6. As shown in FIG. 1B, the external connection leads 4 and 5 are provided with through holes 4A and 5A. Thereby, a part of the package 6 is filled in the through holes 4A and 5A when the package is formed, and good adhesion of the external connection leads 4 and 5 to the package 6 is obtained. The external connection lead 4 is connected to the p-side electrode 3 </ b> A of the LED element 3 through a bonding wire 10. The external connection lead 5 is connected to the n-side electrode 3 </ b> B of the LED element 3 through a bonding wire 10.

(Configuration of package 6)
The package 6 is entirely formed of a thermosetting resin such as an epoxy resin. The metal case 2 is covered so that a part of the case is exposed to the outside, and the external connection leads 4 and 5 are fixed to the metal case 2.

[Operation of Light Emitting Device 1]
When a voltage is applied to the LED element 3 from the power source, light is emitted from the light emitting layer of the LED element 3, and this light is emitted into the sealing member 9. In this case, since the sealing member 9 contains a phosphor, it emits yellow wavelength-converted light when excited by receiving radiated light (blue light) emitted from the LED element 3. For this reason, the blue radiated light radiated from the LED element 3 and the yellow wavelength converted light radiated from the sealing member 9 are mixed to become white light. Then, the light extraction side (illumination target side) is irradiated as white light (including light reflected by the light reflection surfaces 2D to 2H) from the light emission surface of the sealing member 9.

  Next, a method for manufacturing the light emitting device according to this embodiment will be described with reference to FIGS. 4, 5, and 6 (a) to 6 (e).

  FIG. 4 is a diagram showing a case frame used in the method for manufacturing the light emitting device according to the first embodiment of the present invention. 4A is a plan view and FIG. 4B is a front view. FIG. 5 is a view showing a part of the lead frame used in the method for manufacturing the light emitting device according to the first embodiment of the present invention. FIG. 5A is a plan view showing a state before an insulating member is attached to the lead frame. FIG. 5B is a plan view showing a state after the insulating member is attached to the lead frame. 6A to 6E are views for explaining a method for manufacturing the light emitting device according to the first embodiment of the invention. FIG. 6A is a plan view for explaining a frame holding process. FIG. 6B is a plan view for explaining a package forming process. FIG.6 (c) is a front view shown in order to demonstrate the mounting process of an LED element. FIG.6 (d) is a front view shown in order to demonstrate the sealing process of an LED element. FIG. 6E is a front view for explaining a process of forming external connection leads and ribs.

  The manufacturing method of the light emitting device shown in the present embodiment includes “frame holding” and “package formation”, “LED element mounting”, “LED element sealing”, “external connection leads and ribs formation”. Since these steps are sequentially performed, these steps will be described in sequence.

  It is assumed that the case frame 41 is provided with an accommodation space 2A for the metal case 2 and lead insertion holes 2B and 2C in advance as shown in FIG. Further, as shown in FIG. 5A, through holes 4A and 5A of external connection leads 4 and 5 are provided in the intermediate portion of the lead frame 51, and the base end portion (element connection side end portion) is provided at the base end portion. Assume that the insulating member 11 is attached as shown in FIG.

"Preserve Frame"
First, each element connection side end of the lead frame 51 is inserted into the lead insertion holes 2B and 2C of the case frame 41, and the case frame 41 and the lead frame 51 are assembled together. A frame assembly 52 is formed as shown in FIG. In this case, when the element connection side end portions of the lead frame 51 are inserted into the lead insertion holes 2B and 2C, the element connection side end surfaces 51a and 51b of the lead frame 51 are exposed to the accommodation space 2A. In addition, since the insulating member 11 is interposed between each element connection side end of the lead frame 51 and the inner surfaces of the lead insertion holes 2B and 2C, the case frame 41 and the lead frame 51 are assembled so as not to contact each other. It is done.

  Next, the frame assembly 52 is held (loaded) so that a part of the frame assembly 52 is exposed to the outside in a package molding die (not shown) in the mold open state. In this case, when holding the frame assembly 52, the case frame 41 and the lead frame 51 are bent, and each of the case frame 41 and the lead frame 51 is placed on the same surface as the parting surface a of the package molding die. Arrange one side of the tip. This placement operation may be performed in the next step (package formation step). Thereafter, the lead frame 51 is cut at a predetermined position. In this case, when the lead frame 51 is cut, as shown by solid lines in FIG. 6A, lead intermediate bodies 51A and 51B led out from the lead insertion holes 2B and 2C (external connection leads 4 before being bent) 5) is formed.

"Package Formation"
The package 6 is formed by closing the mold for package molding and injecting an epoxy insulating resin (molten resin) into the cavity to solidify. In this case, when the package 6 is formed, the metal case 2 and the rib intermediate bodies 2a and 2b are partially exposed to the outside and covered with the package 6 as shown in FIG. The external connection leads 4 and 5 are fixed to each other.

"Installation of LED elements"
The LED element 3 is accommodated in the accommodating space 2A of the metal case 2 and mounted on the light reflecting surface 2D (case bottom surface) with an adhesive or the like. Next, as illustrated in FIG. 6C, the p-side electrode 3 </ b> A and the n-side electrode 3 </ b> B of the LED element 3 and the element connection side ends of the lead intermediate bodies 51 </ b> A and 51 </ b> B are connected by the bonding wires 10.

"LED element sealing"
The accommodating space 2A of the metal case 2 is filled with the sealing member 9, and the LED element 3 and the bonding wire 10 are sealed as shown in FIG. 6 (d).

"Forming external connection leads and ribs"
After the rib intermediate bodies 2a and 2b shown in FIG. 6 (d) are bent to the side surface side of the package 6, the leading ends thereof are bent to the mounting surface side of the package 6, and the lead intermediate bodies 51A and 5A shown in FIG. After 51B is bent toward the mounting surface side of the package 6, the tip is bent toward the back side of the package 6 to form ribs 2I and 2J and external connection leads 4 and 5, as shown in FIG.
In this way, the light emitting device 1 can be manufactured.

[Effect of the embodiment]
According to the embodiment described above, the following effects can be obtained.

(1) Since the LED element 3 is mounted on the light reflecting surface 2D of the metal base 2 where a part of the case is exposed to the outside, the metal base functions sufficiently as a heat sink, and good heat dissipation can be obtained. In this case, since some of the ribs 2I and 2J are exposed to the outside, the heat generated from the LED element 3 is effectively dissipated to the outside not only through the metal case 2 but also through the ribs 2I and 2J. For this reason, deterioration of the sealing member 9 in the housing space 2A can be prevented, and the life of the light emitting device 1 can be extended.

(2) Since the housing space 2A of the metal case 2 in which the LED element 3 is housed has a structure that widens from the case bottom side toward the light extraction side, the emitted light from the LED element 3 is emitted in a wide-angle direction, and the side surface It can be used as a light source for light emission (light emission).

(3) Since the LED element 3 is accommodated in the metal case 2, the amount of light radiated from the LED element 3 is reduced, and the light extraction efficiency can be increased. In this case, since the inner surface of the metal case 2 is formed by the light reflecting surfaces 2D to 2H, the amount of light leaking out of the metal case 2 can be effectively reduced.

(4) Since the package 6 is formed of a thermosetting resin, thermal deformation of the package 6 can be suppressed, and reliability when the light-emitting device 1 is mounted by soldering can be improved.

(5) Since the metal case 2 is provided with a truncated pyramid-shaped accommodation space 2A extending from the case bottom side toward the light extraction (case opening) side, the sealing member 9 is filled in the metal case 2 It becomes easy to do, and favorable filling workability | operativity of the sealing member 9 can be obtained.

(6) Since the light emitting device 1 can be disposed at a position corresponding to the side surface of the side light incident type light guide plate in the mobile phone, it can be used as a light source for liquid crystal display of a mobile phone that is required to be thin. .

(7) Since the light emitting device 1 can be manufactured by using the transfer mold technique, it is excellent in mass productivity and the cost can be reduced.

  As mentioned above, although the light-emitting device of this invention was demonstrated based on said embodiment, this invention is not limited to said embodiment, It implements in a various aspect in the range which does not deviate from the summary. For example, the following modifications are possible.

(1) In the present embodiment, the step (holding step) of holding the case frame 41 and the lead frame 51 in the package molding die is the inner surface of the lead insertion holes 2B and 2C and the element connection side end of the lead frame 51. However, the present invention is not limited to this, and the through holes 4A and 5A provided in advance in the lead frame 51 as shown in FIG. For example, a holding pin 81 made of synthetic resin may be attached, and the holding step may be executed using the holding pin 81. Moreover, you may perform a holding | maintenance process using the holding part (not shown) previously provided in the metal mold | die for package shaping | molding.

(2) In the present embodiment, the phosphor-containing sealing member 9 that emits yellow wavelength-converted light when excited by receiving radiation light (blue light) emitted from the LED element 3 As described above, the present invention is not limited to this. The phosphor-containing material emits white wavelength-converted light when excited by receiving radiated light (purple light: wavelength 370 to 390 nm) emitted from the LED element. It may be a sealing member.

(3) In this embodiment, the case of a light emitting device using a phosphor has been described. However, the present invention is not limited to this, and may be a light emitting device that does not use a phosphor.

FIGS. 4A to 4D are a front view, a plan view, a side view, and a cross-sectional view taken along line AA, for explaining the light emitting device according to the first embodiment of the present invention. FIGS. The front view which expands and shows the principal part of Fig.1 (a). (A) And (b) is the top view and sectional drawing which show the mounting state to the circuit board of the light-emitting device which concerns on the 1st Embodiment of this invention. (A) And (b) is the top view and front view which show a part of case frame used for the manufacturing method of the light-emitting device which concerns on the 1st Embodiment of this invention. (A) And (b) is a top view which shows the lead frame used for the manufacturing method of the light-emitting device which concerns on the 1st Embodiment of this invention. (A)-(e) is the top view and front view shown in order to demonstrate the manufacturing method of the light-emitting device which concerns on the 1st Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Light-emitting device, 2 ... Metal case, 2A ... Housing space, 2B, 2C ... Lead insertion hole, 2D-2H ... Light reflection surface, 2I, 2J ... Rib, 2a, 2b ... Rib intermediate body, 3 ... LED element, 3A ... p-side electrode, 3B ... n-side electrode, 4,5 ... lead for external connection, 4A, 5A ... through hole, 6 ... package, 7 ... circuit board, 7A ... copper foil part, 7B ... resist pattern, 8 ... Solder, 9 ... Sealing member, 10 ... Bonding wire, 11 ... Insulating member, 41 ... Case frame, 51 ... Lead frame, 51A, 51B ... Lead intermediate, 51a, 51b ... Element connection side end face, 52 ... Frame assembly Body, a ... Parting surface

Claims (12)

A metal having a concave element housing space having an element mounting area for mounting a light emitting element on the bottom surface, and having a pair of lead insertion holes that penetrate the metal case in the vicinity of the element mounting area and communicate with the element housing space Case and
A pair of leads whose tips are fixed to the pair of lead insertion holes via insulating members;
A light emitting element mounted on the element mounting region and connected to the pair of leads via a bonding wire;
A sealing member that fills the element housing space and seals the light emitting element;
A light emitting device comprising: a package member in which the other end of the pair of leads is exposed to the outside and the metal case and the pair of leads are embedded.   The light emitting device according to claim 1, wherein the external connection lead has a bent portion for restricting lead movement.   3. The light emitting device according to claim 1, wherein an inner surface of the metal case is formed of a light reflecting surface for reflecting light emitted from the light emitting element in a light extraction direction.   The light-emitting device according to claim 1, wherein the insulating member is a thermosetting resin.   The light emitting device according to any one of claims 1 to 4, wherein the metal case has a pair of ribs whose tips are exposed to the outside from the package member.   The light emitting device according to claim 1, wherein the sealing member is made of a material different from that of the package member.   The light emitting device according to claim 1, wherein the sealing member is made of the same material as the package member. A metal case having a housing space extending from the case bottom side toward the light extraction side and a lead insertion hole communicating with the housing space;
A light emitting element mounted on the bottom surface of the metal case and sealed with a sealing member in the housing space;
An external connection lead connected to the light emitting element and led out of the metal case from the lead insertion hole;
A method of manufacturing a light emitting device comprising: a package made of an insulating resin for covering the metal case such that a part of the case is exposed to the outside, and fixing the external connection lead to the metal case,
A first step of assembling the case frame serving as the metal case and the lead frame serving as the external connection lead so as not to contact each other and holding the package in a package molding die;
And a second step of forming the package by injecting an insulating resin into the package molding die.   9. The light emitting device according to claim 8, wherein the second step is executed by disposing the side surfaces of the tip end portions of the case frame and the lead frame on the same surface as the parting surface of the package molding die. Manufacturing method.   10. The method of manufacturing a light emitting device according to claim 8, wherein the first step is performed by interposing an insulating member between an inner surface of the lead insertion hole and an element connection side end of the lead frame.   10. The method of manufacturing a light emitting device according to claim 8, wherein the first step is performed by attaching a holding pin to a through hole provided in advance in the lead frame and using the holding pin.   The light emitting device manufacturing method according to claim 8, wherein the first step is performed using a holding portion provided in advance in the package molding die.