Light-emitting device

Abstract

To improve the heat dissipation performance of the light-emitting device. [Solution] The light-emitting element package 10 comprises a lead frame 20 having a first lead piece 21 and a second lead piece 22 separated from the first lead piece 21; a light-emitting element chip 12 disposed on the first lead piece 21 or disposed on the lead frame 20 so as to straddle the first lead piece 21 and the second lead piece 22; and a metal piece 24 laminated on the lead frame 20 with an insulating layer in between on the same side as the light-emitting element chip 12.

Description

Technical Field

[0001] The present invention relates to a light-emitting device, for example, a light-emitting element package.

Background Art

[0002] Conventionally, a light-emitting module equipped with a light-emitting diode (LED) has been known (see, for example, Patent Document 1). In this light-emitting module, the LED is electrically connected to the electrode pattern of the mother board via a polyhedral substrate.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Generally, a light-emitting device equipped with a light-emitting element such as an LED is used in various lighting fixtures such as vehicle lamps. In order to improve the performance of the lighting fixture, it may be desirable to use a higher-brightness light-emitting element. Here, the problem that may arise is that a high-brightness light-emitting element generates a large amount of heat when lit. An excessive temperature rise of the light-emitting element that may occur due to heat generation may have an adverse effect on the light-emitting element, such as a decrease in light-emitting efficiency and lifespan.

[0005] The present invention has been made in view of such a situation, and an exemplary object of one aspect thereof is to improve the heat dissipation performance of the light-emitting device.

Means for Solving the Problems

[0006] According to one aspect of the present invention, the light-emitting device comprises a lead frame having a first lead piece and a second lead piece separated from the first lead piece; a light-emitting element chip disposed on the first lead piece or disposed on the lead frame so as to straddle the first lead piece and the second lead piece; and a metal piece laminated on the lead frame with an insulating layer in between on the same side as the light-emitting element chip. [Effects of the Invention]

[0007] According to the present invention, the heat dissipation performance of the light-emitting device can be improved. [Brief explanation of the drawing]

[0008] [Figure 1] This figure schematically shows a light-emitting element package according to an embodiment. [Figure 2] This figure schematically shows a light-emitting element package according to an embodiment. [Figure 3] This figure schematically shows a light-emitting element package according to an embodiment. [Figure 4] This figure schematically shows a light-emitting element package related to a comparative example. [Figure 5] Figures 5(a) and 5(b) schematically show a modified light-emitting element package. [Figure 6] Figures 6(a) and 6(b) schematically show a light-emitting element package according to another embodiment. [Figure 7] Figures 7(a) and 7(b) schematically show light-emitting element packages according to other embodiments. [Modes for carrying out the invention]

[0009] The present invention will be described below with reference to the drawings, based on preferred embodiments. The embodiments are illustrative and not limiting, and not all features or combinations thereof described in the embodiments are necessarily essential to the invention. The same or equivalent components, members, and processes shown in each drawing are denoted by the same reference numerals, and redundant explanations are omitted as appropriate. Furthermore, the scale and shape of each part shown in each drawing are set for convenience to facilitate explanation and are not to be interpreted restrictively unless otherwise specified. In addition, terms such as "first," "second," etc., used in this specification or claims do not indicate any order or importance, but are used to distinguish one configuration from another. Furthermore, some components that are not important for explaining the embodiments are omitted in each drawing.

[0010] Figures 1 to 3 are schematic diagrams showing an embodiment of a light-emitting element package. Figure 1 shows a top view of the light-emitting element package 10. Figure 2 shows a cross-section of the light-emitting element package 10 shown in Figure 1 along line AA. Figure 3 shows a cross-section of the light-emitting element package 10 shown in Figure 1 along line BB.

[0011] For the sake of explanation, the height direction of the light-emitting element package 10 will be referred to as the Z direction, and the two mutually orthogonal directions in the XY plane perpendicular to the Z direction will be referred to as the X direction and the Y direction. Therefore, Figure 1 shows the light-emitting element package 10 as viewed in the Z direction. Figure 2 shows the XZ cross-section of the light-emitting element package 10, and Figure 3 shows the YZ cross-section of the light-emitting element package 10.

[0012] The light-emitting element package 10 may be mounted on a vehicle light fixture, such as a headlamp, and used as a light source for such a vehicle light fixture. Alternatively, the light-emitting element package 10 may be a light source for other lighting fixtures.

[0013] As shown in Figures 1 to 3, the light-emitting element package 10 comprises a light-emitting element chip 12, a body 14, a lead frame 20, and a metal piece 24. The light-emitting element package 10 is mounted on a circuit board 50, such as a printed circuit board. The circuit board 50 is positioned perpendicular to the Z direction, and the surface of the circuit board 50 on which the light-emitting element package 10 is mounted is parallel to the XY plane.

[0014] In this example, the light-emitting element chip 12 is a so-called vertical LED chip. A vertical LED chip has one electrode (hereinafter also referred to as the first electrode) on its lower surface and the other electrode (hereinafter also referred to as the second electrode) on its upper surface. When powered, the light-emitting element chip 12 can emit light from its upper surface in the Z direction. Therefore, in this example, the light-emitting element package 10 can emit light in a direction perpendicular to the surface of the circuit board 50.

[0015] The body 14 is a housing that contains the light-emitting element chip 12 and defines the external shape of the light-emitting element package 10. The body 14 has a cavity inside, and the light-emitting element chip 12 is placed in this cavity. In this example, the body 14 has a rectangular (e.g., square) external shape when viewed from above, as shown in Figure 1. The cavity also has a rectangular shape when viewed from above. However, the shape of the body 14 (and cavity) is not limited to a rectangle. The body 14 may have other polygonal shapes, or other shapes such as a circle.

[0016] The cavity of the body 14 is filled with sealing resin 16. The height of the top surface of the body 14 (position in the Z direction) is higher than the top surface of the light-emitting element chip 12 so that the entire light-emitting element chip 12 can be covered with the sealing resin 16 filling the cavity. The sealing resin 16 is transparent to the light emitted by the light-emitting element chip 12. The sealing resin 16 may contain a phosphor that wavelength-converts the light emitted by the light-emitting element chip 12.

[0017] The body 14 may be formed of, for example, ceramics, a resin material, or other insulating materials. The body 14 may be formed of a high thermal conductivity material such as, for example, aluminum nitride. Alternatively, as described later, the body 14 may be formed of a metal material such as, for example, copper, or other conductive materials.

[0018] The body 14 may be used as a reflector. That is, the inner peripheral surface 14a of the body 14 that forms the cavity may be used as a reflecting surface that reflects the light emitted by the light emitting element chip 12. In the illustrated example, the inner peripheral surface 14a of the body 14 is perpendicular to the XY plane, but instead, it may be inclined with respect to the XY plane. In addition, in order to reflect the light from the light emitting element chip 12 upward, the inner peripheral surface 14a of the body 14 may be inclined so as to widen outward as it goes upward from the bottom surface of the cavity. Such a reflecting surface may be a paraboloidal curved surface. In order to increase the reflectance, the reflecting surface may be coated with a high reflectance coating such as, for example, aluminum, silver, nickel, etc.

[0019] The lead frame 20 includes a first lead piece 21 on which the light emitting element chip 12 is disposed, and a second lead piece 22 separated from the first lead piece 21. The light emitting element chip 12 is disposed at the center of the first lead piece 21. The first lead piece 21 and the second lead piece 22 do not contact each other. The gap between the first lead piece 21 and the second lead piece 22 may be filled with an insulating resin material 23 such as an insulating adhesive. In addition, in order to increase the thermal conductivity, the insulating resin material 23 may be a high heat dissipation insulating adhesive containing an insulating filler (for example, alumina powder, etc.) having a higher thermal conductivity than the insulating resin material 23. The high heat dissipation insulating adhesive may be obtained by kneading an insulating filler having a high thermal conductivity into an insulating adhesive serving as a base material. Alternatively, the first lead piece 21 and the second lead piece 22 may be connected via other insulating materials.

[0020] The first lead piece 21 and the second lead piece 22 are each coupled to the body 14 at the bottom of the body 14 and define the bottom surface of the cavity of the body 14. The first lead piece 21 and the second lead piece 22 may each be a thin plate arranged along the XY plane.

[0021] The first lead piece 21 and the second lead piece 22 are formed of, for example, copper. Alternatively, the first lead piece 21 and the second lead piece 22 may be formed of other metal materials such as aluminum or iron, or other conductive materials.

[0022] The lead frame 20 is electrically connected to the circuit board 50 on the surface opposite to the light-emitting element chip 12. The first lead piece 21 and the second lead piece 22 are each connected to conductive patterns of different polarities on the circuit board 50.

[0023] As shown in FIG. 1, the first lead piece 21 is larger in size than the second lead piece 22 in top view. In this example, the first lead piece 21 is larger than the second lead piece 22 in the X direction and also larger than the second lead piece 22 in the Y direction.

[0024] The first lead piece 21 occupies most of the bottom surface of the cavity of the body 14. For example, the first lead piece 21 may occupy at least 90% or at least 95% of the bottom surface of the cavity of the body 14.

[0025] The first lead piece 21 has a notch 21a in which the second lead piece 22 is disposed. In order to separate the first lead piece 21 and the second lead piece 22 from each other as described above, the size of the notch 21a is somewhat larger than the size of the second lead piece 22. In this example, the notch 21a of the first lead piece 21 is formed at the end (the lower right end in FIG. 1) of the bottom surface of the cavity of the body 14. The second lead piece 22 has a square shape in top view. Therefore, the notch 21a also has a square shape in top view and surrounds the second lead piece 22.

[0026] As described above, the light-emitting element chip 12 is located on the first lead piece 21 and not on the second lead piece 22. Therefore, the second lead piece 22 may be smaller in size than the light-emitting element chip 12 when viewed from above.

[0027] As shown in Figures 2 and 3, the metal piece 24 is laminated on the lead frame 20 on the same side as the light-emitting element chip 12, with an insulating layer 26 in between. In this example, the metal piece 24 is laminated on the first lead piece 21 in the Z direction. The metal piece 24 may be a thin plate arranged along the XY plane, elongated in the Y direction along one side of the first lead piece 21 (the right side in Figure 1). The metal piece 24 is not in contact with the first lead piece 21 due to the insulating layer 26. The metal piece 24 is also not in contact with the second lead piece 22.

[0028] Furthermore, the metal piece 24 may extend along multiple sides of the first lead piece 21. For example, the metal piece 24 may extend along two, three, or four adjacent sides of the first lead piece 21. In other words, the metal piece 24 may extend along a part of the circumference of the first lead piece 21, or it may extend along the entire circumference of the first lead piece 21.

[0029] The metal piece 24 is adjacent to the light-emitting element chip 12 when viewed in the Z direction. In this example, as shown in Figure 1, the metal piece 24 is adjacent to the light-emitting element chip 12 in the X direction on the first lead piece 21.

[0030] Furthermore, the metal piece 24 is adjacent to the second lead piece 22 when viewed in the Z direction. In this example, as shown in Figure 1, the metal piece 24 is adjacent to the second lead piece 22 in the Y direction. The metal piece 24 has the same width as the second lead piece 22 in the X direction and is longer than the second lead piece 22 in the Y direction. Note that the metal piece 24 may have a different width from the second lead piece 22; for example, the metal piece 24 may have a wider width than the second lead piece 22 in the X direction and may be close to the light-emitting element chip 12.

[0031] The metal piece 24 is formed of, for example, copper. Alternatively, the metal piece 24 may be formed of aluminum, iron, or other metallic materials, or other conductive materials. The metal piece 24 may be formed of the same material as the lead frame 20, or it may be formed of a different material.

[0032] The insulating layer 26 may be formed of an insulating resin material 23 such as an insulating adhesive, or other insulating material. The insulating layer 26 may be formed of the same material as the insulating material separating the first lead piece 21 and the second lead piece 22, or it may be formed of a different material.

[0033] In this embodiment, the lead frame 20, together with the metal piece 24, constitutes a power supply path from an external power source (not shown) to the light-emitting element chip 12. The first electrode (bottom electrode) of the light-emitting element chip 12 is electrically connected to the first lead piece 21, and the second electrode (top electrode) of the light-emitting element chip 12 is electrically connected to the second lead piece 22 via the metal piece 24. More specifically, the first electrode of the light-emitting element chip 12 is connected to the surface of the first lead piece 21 via a conductive layer (not shown) such as solder or conductive adhesive. The second electrode of the light-emitting element chip 12 is connected to the metal piece 24 by a bonding wire 28. The metal piece 24 is connected to the second lead piece 22 by a bonding wire 30. The bonding wire is formed of, for example, gold or other conductive material. As described above, the first lead piece 21 and the second lead piece 22 are each connected to conductive patterns of different polarities on the circuit board 50 on the side opposite to the light-emitting element chip 12. In this way, the light-emitting element package 10 is connected to an external power source through the circuit board 50.

[0034] As described above, since the metal piece 24 is positioned adjacent to the light-emitting element chip 12, the bonding wire 28 connecting them can be shortened. Also, since the metal piece 24 is positioned adjacent to the second lead piece 22, the bonding wire 30 connecting them can be shortened.

[0035] The light-emitting element package 10 may include an electrostatic discharge (ESD) protection element 32, such as a Zener diode. The ESD protection element 32, like the light-emitting element chip 12, is located within the cavity of the body 14 and covered with a sealing resin 16. In this example, the ESD protection element 32 is located on a metal piece 24. The lower electrode of the ESD protection element 32 is connected to the metal piece 24, and the upper electrode of the ESD protection element 32 is connected to the first lead piece 21 by a bonding wire 34. In this way, the ESD protection element 32 is connected in parallel with the light-emitting element chip 12. The ESD protection element 32 may also be located on the first lead piece 21 and connected to the metal piece 24 by a bonding wire 34.

[0036] Figure 4 is a schematic diagram showing a light-emitting element package according to a comparative example. Figure 4 shows a top view of an example of a typical existing light-emitting element package 110. The light-emitting element package 110 comprises a light-emitting element chip 112, a body 114, and a lead frame 120. Unlike the light-emitting element package 10 according to the above-described embodiment, the light-emitting element package 110 does not include a metal piece 24.

[0037] The lead frame 120 comprises a first lead piece 121 on which the light-emitting element chip 112 is positioned, and a second lead piece 122 separated from the first lead piece 121. The first lead piece 121 is positioned on one side (left side in Figure 4) within the cavity of the body 114, and the second lead piece 122 is positioned on the opposite side (right side in Figure 4) within the cavity of the body 114. The first lead piece 121 is longer than the second lead piece 122 in the X direction, but equal in length to the second lead piece 122 in the Y direction. The electrodes on the lower surface of the light-emitting element chip 112 are electrically connected to the first lead piece 121, and the electrodes on the upper surface of the light-emitting element chip 112 are electrically connected to the second lead piece 122 by bonding wires 128.

[0038] Furthermore, the light-emitting element package 110 may also include an electrostatic discharge protection element 132 connected in parallel with the light-emitting element chip 112. The electrostatic discharge protection element 132 may be located on a second lead piece 122 and connected to a first lead piece 121 by a bonding wire 134.

[0039] In the comparative example light-emitting element package 110, the size of the second lead piece 122 in the XY plane is relatively large, which limits the area of ​​the first lead piece 121 in the XY plane. Since the first lead piece 121 is in contact with the light-emitting element chip 112, the heat dissipation performance of the light-emitting element package 110 is significantly affected by the area of ​​the first lead piece 121. The smaller the area of ​​the first lead piece 121, the lower the heat dissipation performance of the light-emitting element package 110 tends to be.

[0040] In contrast, according to the light-emitting element package 10 of the embodiment, as can be seen from the comparison between Figure 1 and Figure 4, the introduction of the metal piece 24 allows for the expansion of the first lead piece 21. In the comparative example in Figure 4, the first lead piece 121 is larger than the second lead piece 122 in the X direction, but equal in size to the second lead piece 122 in the Y direction. On the other hand, as shown in Figure 1, the first lead piece 21 is larger than the second lead piece 22 in both the X and Y directions. The area of ​​the first lead piece 21 in the XY plane is increased, thereby improving the heat dissipation capacity of the first lead piece 21 against heat generated from the light-emitting element chip 12 during illumination. Thus, the heat dissipation performance of the light-emitting element package 10 is improved.

[0041] Furthermore, the light-emitting element package 10 according to the embodiment can achieve both miniaturization and improved heat dissipation performance. Even if the light-emitting element package 10 according to the embodiment is smaller than the light-emitting element package 110 of the comparative example, it can provide the same heat dissipation performance as the light-emitting element package 110. In other words, the light-emitting element package 10 according to the embodiment can provide higher heat dissipation performance while maintaining the same external dimensions as the light-emitting element package 110 of the comparative example.

[0042] Furthermore, according to the embodiment of the light-emitting element package 10, not only the lead frame 20 but also the metal piece 24 can function as a heat dissipation member. Therefore, the light-emitting element package 10 can provide higher heat dissipation performance compared to the comparative example light-emitting element package 110 by adding the metal piece 24.

[0043] Furthermore, the light-emitting element chip 12 is positioned in the center of the first lead piece 21. Therefore, heat can be dissipated evenly from the light-emitting element chip 12 towards the outer circumference of the first lead piece 21.

[0044] Figures 5(a) and 5(b) schematically show a modified light-emitting element package. Similar to Figure 3, Figures 5(a) and 5(b) show the YZ cross-section of the light-emitting element package 10.

[0045] As shown in Figure 5(a), the metal piece 24 may be positioned overlapping the second lead piece 22 when viewed in the Z direction. The metal piece 24 may be electrically connected to the second lead piece 22 via a conductive layer 29 such as solder or conductive adhesive. Alternatively, the metal piece 24 may be electrically connected by contact with the second lead piece 22. In this way, a bonding wire is not required to connect the metal piece 24 and the second lead piece 22.

[0046] As shown in Figure 5(b), the height (Z-direction position) of the second lead piece 22 and the metal piece 24 may be aligned. In this way, the second lead piece 22 and the metal piece 24 can be connected with a shorter bonding wire 30.

[0047] Figures 6(a) and 6(b) schematically show a light-emitting element package according to another embodiment. Figure 6(a) shows a front view of the light-emitting element package 10, and Figure 6(b) shows a side view of the light-emitting element package 10. The light-emitting element package 10 may be a so-called side-view type light-emitting element package in which the light-emitting element chip 12 is mounted on the circuit board 50 such that it emits light in a direction parallel to the surface of the circuit board 50 (the Z direction in Figures 6(a) and 6(b)).

[0048] The light-emitting element package 10 comprises a light-emitting element chip 12, a lead frame 20, and a metal piece 24.

[0049] In this embodiment, the metal piece 24 is electrically insulated from the light-emitting element chip 12 and the lead frame 20. The metal piece 24 serves the same role as the body 14 in the above-described embodiment. The metal piece 24 is laminated on the lead frame 20 on the same side as the light-emitting element chip 12 via an insulating layer 26. The metal piece 24 is laminated on the lead frame 20 in the Z direction and extends along the entire circumference of the lead frame 20. The metal piece 24 has a frame shape that forms a cavity inside it, and the light-emitting element chip 12 is placed in this cavity. The cavity is filled with sealing resin 16. The height of the top surface of the metal piece 24 (Z direction position) is higher than the top surface of the light-emitting element chip 12 so that the entire light-emitting element chip 12 can be covered with the sealing resin 16 filling the cavity.

[0050] The metal piece 24 may be used as a reflector. That is, the inner circumferential surface 24a of the frame-shaped metal piece 24 that forms the cavity may be used as a reflective surface that reflects the light emitted by the light-emitting element chip 12. In the illustrated example, the inner circumferential surface 24a of the metal piece 24 is perpendicular to the lead frame 20, but it may be inclined with respect to the lead frame 20 instead. For example, the inner circumferential surface 24a of the metal piece 24 may be inclined to widen outward as it extends upward from the lead frame 20. Such a reflective surface may be a parabolic curved surface. To increase reflectivity, the reflective surface may be coated with a highly reflective coating, such as aluminum, silver, or nickel.

[0051] The lead frame 20 comprises a first lead piece 21 on which the light-emitting element chip 12 is positioned, and a second lead piece 22 separated from the first lead piece 21. The light-emitting element chip 12 is positioned in the center of the first lead piece 21. The gap between the first lead piece 21 and the second lead piece 22 may be filled with an insulating resin material 23, such as an insulating adhesive, as well as an insulating layer 26. The first lead piece 21 is positioned on one side (right side in Figure 6(a)), and the second lead piece 22 is positioned on the opposite side (left side in Figure 6(a)). The first electrode of the light-emitting element chip 12 is electrically connected to the first lead piece 21, and the second electrode of the light-emitting element chip 12 is electrically connected to the second lead piece 22 by a bonding wire 28. The lead frame 20 is electrically connected to the circuit board 50 on its side (bottom surface in Figures 6(a) and 6(b)). The first lead piece 21 and the second lead piece 22 are each connected to conductive patterns of different polarities on the circuit board 50.

[0052] The first lead piece 21 and the second lead piece 22 may each be thin plates arranged along the XY plane, and may have a bent portion 36 on one side. The first lead piece 21 and the second lead piece 22 may be electrically connected to the circuit board 50 at the bent portion 36. By forming the bent portion 36, a sufficient area for connection to the circuit board 50 can be secured. Alternatively, instead of providing the bent portion 36 on the lead frame 20, the lead frame 20 may be formed from a thick plate to increase the surface area of ​​the side that connects to the circuit board 50.

[0053] In typical existing side-view light-emitting element packages, the body surrounding the encapsulating resin is made of an insulating material such as resin. This body does not substantially contribute to the heat dissipation performance of the light-emitting element package, and the lead frame alone provides heat dissipation.

[0054] In contrast, according to this embodiment, not only the lead frame 20 but also the metal piece 24 can function as a heat dissipation member. Therefore, the heat dissipation performance of the light-emitting element package 10 is improved. Furthermore, the light-emitting element package 10 according to this embodiment can achieve both miniaturization and improved heat dissipation performance.

[0055] Figures 7(a) and 7(b) schematically show light-emitting element packages according to other embodiments. Figure 7(a) shows the XZ cross-section of the light-emitting element package 10, and Figure 7(b) shows a part of the top view of the light-emitting element package 10.

[0056] The light-emitting element package 10 comprises a light-emitting element chip 12, a lead frame 20, and a metal piece 24.

[0057] In this embodiment, as in the embodiments shown in Figures 6(a) and 6(b), the metal piece 24 is electrically insulated from the light-emitting element chip 12 and the lead frame 20. The metal piece 24 serves the same role as the body 14 in the embodiments described above. The metal piece 24 is laminated on the lead frame 20 on the same side as the light-emitting element chip 12 via an insulating layer 26. The metal piece 24 is laminated on the lead frame 20 in the Z direction and extends along the entire circumference of the lead frame 20. The metal piece 24 has a frame shape that forms a cavity inside it, and the light-emitting element chip 12 is placed in this cavity. The cavity may be filled with a sealing resin.

[0058] The metal piece 24 may be used as a reflector. That is, the inner circumferential surface 24a of the frame-shaped metal piece 24 forming the cavity may be used as a reflective surface that reflects the light emitted by the light-emitting element chip 12. In order to reflect the light from the light-emitting element chip 12 upward, the inner circumferential surface 24a of the metal piece 24 may be inclined to widen outward as it extends upward from the lead frame 20. Such a reflective surface may be a parabolic curved surface. To increase reflectivity, the reflective surface may be coated with a highly reflective coating, such as aluminum, silver, or nickel.

[0059] The lead frame 20 comprises a first lead piece 21 and a second lead piece 22 separated from the first lead piece 21. The gap between the first lead piece 21 and the second lead piece 22 may be filled with an insulating resin material such as an insulating adhesive, similar to the insulating layer 26, to form an insulating line 38. The first lead piece 21 is located on one side (left side in Figure 7(a)), and the second lead piece 22 is located on the opposite side (right side in Figure 7(a)). The lead frame 20 is electrically connected to the circuit board 50 on the side opposite to the light-emitting element chip 12, and the first lead piece 21 and the second lead piece 22 are each connected to conductive patterns of different polarities on the circuit board 50.

[0060] The light-emitting element chip 12 is positioned on the lead frame 20 so as to straddle the first lead piece 21 and the second lead piece 22. In other words, the light-emitting element chip 12 is a flip-chip type and is mounted on the chip mounting section of the lead frame 20.

[0061] Figure 7(b) shows the chip mounting section 40 on the lead frame 20 for the light-emitting element package 10 shown in Figure 7(a). The light-emitting element chip 12 mounted on the chip mounting section 40 is schematically shown by a dashed line. The chip mounting section 40 includes a cathode portion 41 on the first lead piece 21 and an anode portion 42 on the second lead piece 22 (conversely, the first lead piece 21 may have the anode portion and the second lead piece 22 may have the cathode portion 41).

[0062] The lower surface of the light-emitting element chip 12 is provided with a cathode bump and an anode bump (not shown), and the insulating line 38 is bent or curved so as to position the cathode portion 41 and anode portion 42 on the lead frame 20 in accordance with the arrangement of the cathode bump and anode bump of the light-emitting element chip 12. The cathode bump is joined to the cathode portion 41 and the anode bump is joined to the anode portion 42, and the light-emitting element chip 12 is electrically connected to the lead frame 20. When powered, the light-emitting element chip 12 can emit light from its upper surface in the Z direction.

[0063] According to this embodiment, not only the lead frame 20 but also the metal piece 24 can function as a heat dissipation member. Therefore, the heat dissipation performance of the light-emitting element package 10 is improved. Furthermore, the light-emitting element package 10 according to this embodiment can achieve both miniaturization and improved heat dissipation performance.

[0064] The thermal conductivity of copper is approximately 400 W / mK. While the thermal conductivity of high-thermal-conductivity ceramics (e.g., aluminum nitride) that can be used in existing light-emitting element packages is approximately 200 W / mK, the thermal conductivity of copper is twice that, at approximately 400 W / mK. Therefore, when the metal piece 24 is formed of copper, the heat dissipation performance of the light-emitting element package 10 is expected to be significantly improved.

[0065] The present invention is not limited to the embodiments and modifications described above. It is also possible to combine embodiments and modifications, or to make further modifications such as various design changes based on the knowledge of those skilled in the art. Embodiments and modifications that are thus combined or further modified are also included in the scope of the present invention. The embodiments and modifications described above, and new embodiments resulting from combinations of the embodiments and modifications described above with the following modifications, combine the effects of the combined embodiments, modifications, and further modifications.

[0066] In the embodiments described with reference to Figures 1 to 6, as in the embodiments shown in Figures 7(a) and 7(b), the light-emitting element chip 12 may be of the flip-chip type and may be arranged on the lead frame 20 so as to straddle the first lead piece 21 and the second lead piece 22. Also, in the embodiments shown in Figures 7(a) and 7(b), the light-emitting element chip 12 may be of the vertical type and may be arranged on the first lead piece 21 and connected to the second lead piece 22 by a bonding wire.

[0067] The light-emitting element chip 12 is not limited to an LED chip. The light-emitting element chip 12 may be other semiconductor light-emitting elements or other types of light-emitting elements.

[0068] The surface of the light-emitting element package 10, for example, the metal surface of the metal piece 24, may be treated with a surface treatment to prevent corrosion (e.g., rust prevention).

[0069] Although the present invention has been described using specific terms based on the embodiments, the embodiments only illustrate one aspect of the principle and application of the present invention, and many modifications and changes in arrangement are permitted in the embodiments, as long as they do not depart from the spirit of the present invention as defined in the claims. [Explanation of symbols]

[0070] 10 light-emitting element package, 12 light-emitting element chip, 20 lead frame, 21 first lead piece, 22 second lead piece, 24 metal piece, 26 insulating layer, 32 electrostatic protection element.

Claims

1. A lead frame comprising a first lead piece and a second lead piece separated from the first lead piece, A light-emitting element chip is disposed on the first lead piece, or is disposed on the lead frame so as to straddle the first lead piece and the second lead piece, A light-emitting device characterized by comprising a metal piece laminated on the lead frame via an insulating layer on the same side as the light-emitting chip.

2. The light-emitting element chip is arranged on the first lead piece, The light-emitting device according to claim 1, characterized in that the first electrode of the light-emitting chip is electrically connected to the first lead piece, and the second electrode of the light-emitting chip is electrically connected to the second lead piece via the metal piece.

3. The light-emitting device according to claim 2, characterized in that, when the stacking direction of the metal piece onto the lead frame is the Z direction, the first lead piece is larger than the second lead piece in the X direction perpendicular to the Z direction, and is also larger than the second lead piece in the Y direction perpendicular to both the Z and X directions.

4. The light-emitting device according to claim 3, characterized in that the light-emitting element chip is located in the center of the first lead piece.

5. The light-emitting device according to claim 3, characterized in that the metal piece is arranged adjacent to or overlapping with the second lead piece when viewed in the Z direction.

6. The light-emitting device according to claim 1, characterized in that the metal piece is electrically insulated from the light-emitting chip and the lead frame.

7. The light-emitting device according to claim 6, characterized in that the metal piece has a frame shape that forms a cavity on the inside, and the light-emitting chip is arranged in the cavity.

8. The light-emitting device according to claim 7, characterized in that the frame shape has an inner circumferential surface that defines the cavity, and the inner circumferential surface is inclined to spread outward upward from the lead frame.

9. The light-emitting device according to any one of claims 1 to 8, further comprising an electrostatic protection element connected in parallel with the light-emitting chip.

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