JP5359135B2 - Light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting device capable of favorably radiating the heat of the device. <P>SOLUTION: The light emitting device includes a molded member having a recess in which a light emitting element is placed at the front surface, and positive and negative lead frames having an inner lead embedded in the molded member and an outer lead protruding from the bottom surface of the molded member. The molded member has a pair of first cut parts on the rear surface opposing the front surface. The outer lead includes the first end bent along the first cut part and the second end bent along the side surface adjoining the front surface. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a light emitting device, and more particularly to a light emitting device having a structure for emitting light in a direction parallel to a mounting surface.

  For example, as shown in Patent Document 1, these light-emitting devices include a package having a recess in which a light-emitting element is mounted on the front surface and a light-emitting element mounted in the recess. It is used as a backlight for liquid crystal display devices of necessary mobile communication devices.

As shown in FIG. 5, in the light emitting device disclosed in Patent Document 1, the lead electrode 504 drawn out of the molded body is bent along the bottom surface and further bent along the side surface.
JP 2007-165803 A

However, in recent years, there has been an increasing demand for downsizing of light emitting devices. However, as the area of the outer leads becomes smaller due to downsizing, there is a new problem that sufficient heat dissipation cannot be secured.
In order to cope with this problem, if the outer leads are made relatively small while being kept relatively large, the distance between the positive and negative outer leads is reduced and the risk of short-circuiting is increased. is there.

  Therefore, an object of the present invention is to provide a light emitting device that can dissipate heat generated from the light emitting device satisfactorily and can effectively prevent a short circuit between positive and negative outer leads.

In order to achieve the above object, a light-emitting device according to the present invention includes a molded member having a recess for mounting a light-emitting element on the front surface,
A light emitting device having an inner lead portion embedded in the molding member and a positive and negative lead frame having an outer lead portion protruding from the bottom surface of the molding member,
The molded member is
(A) a pair of first cutout portions for holding the outer lead portion of the positive lead frame and the outer lead portion of the negative lead frame at a predetermined distance or more on the back surface facing the front surface ;
(B) having a second cutout portion on the back surface side of the side surface connecting the front surface and the back surface ;
(C) The first notch and the second notch are formed separately from each other,
Wherein each outer lead portion, possess a first end which is folded along said first notch portion, and a second end portion which is bent along said second cut-out portion on the side surface,
The bottom surface has a stepped portion in which a main portion excluding the first end portion and the second end portion among the bent outer lead portions is accommodated, and the grounding surface of the outer lead portion and the bottom surface The portion excluding the step portion is located on the same plane .

  The main portion may have a branch point and extend in the opposite direction, and the extended tip may be the first end and the second end, respectively.

The main portion may extend toward the first end and the second end.
Furthermore, the shape of the first notch may be a quadrangular prism.
Furthermore, it is preferable that the first notch has a depth such that the first end portion does not protrude from the outermost shape when viewed from the back surface of the molded member.

  In the light emitting device according to the present invention configured as described above, the outer lead portion has a first end portion that is bent along the first notch portion, and a side surface that is adjacent to both the front surface and the bottom surface. Since the outer lead portion has a second end portion that can be bent, the area of the outer lead portion can be made relatively large, heat generated from the light emitting device can be radiated well, and the first end portion of the positive and negative outer leads can be disposed between the first end portion. A short circuit between the positive and negative outer leads can be prevented without approaching the interval between the notches.

  Hereinafter, a light emitting device according to an embodiment of the present invention will be described with reference to the drawings.

  1A is a perspective view of a light-emitting device according to an embodiment of the present invention as viewed obliquely from above, FIG. 1B is a front view of FIG. 1A, FIG. 1C is a perspective view of FIG. 1A as viewed from obliquely below, and FIG. FIG. 1B is a side view of FIG. 1A. FIG. 2A is a perspective view of still another light emitting device according to an embodiment of the present invention as viewed obliquely from above, and FIG. 2B is a perspective view of FIG. 2A as viewed from obliquely below. In the present specification, the bottom surface side serving as a mounting surface is assumed to be the lower side, and the upper surface side facing the bottom surface is assumed to be the upper side.

  The light-emitting device of the embodiment includes a molding member having a side surface in which a front surface and a bottom surface on which a concave portion in which a light-emitting element is placed is provided, and a lead frame, and a pair of the lead frame and the molding member 10. It is integrally molded.

In the light emitting device of the embodiment, as shown in FIGS. 1A to 1D, each lead frame includes an inner lead portion 4 embedded in the molding member 10 and an outer lead portion 21 protruding from the bottom surface 16 of the molding member 10. The outer lead portion 21 is bent along the bottom surface 16 of the molding member 10. In particular, in the light emitting device of the present invention, the first notch portion 11 is provided on the back surface 19 facing the front surface 14, and the outer lead portion 21 is bent along the first notch portion 11. 21r and a second end 21t that is bent along the side surface 18 adjacent to both the front surface 14 and the bottom surface 16 is characterized. The light emitting device of the present invention configured as described above can increase the number of places where the outer lead portion 21 is disposed, and can increase the surface area of the outer lead portion. Thereby, the heat dissipation of an outer lead part can be improved and the heat dissipation of a light-emitting device can be improved.
On the other hand, each of the first end portions 21r of the outer lead portion 21 is bent along the first cutout portion 11, so that the distance between the first end portions 21r is shorter than the interval between the pair of first cutout portions 11. There is nothing.
Therefore, even when the dimensions of the outer lead portion 21 vary due to problems such as processing accuracy, the distance between the first end portions 21r does not become shorter than the interval between the first cutout portions 11, and the positive and negative outer A short circuit between the lead portions 21 can be prevented.

  Hereinafter, the light emitting device of the embodiment according to the present invention will be described in more detail. In addition, the light-emitting device of embodiment contains the more preferable specific structure in this invention, and this invention is not limited to the specific structure demonstrated below.

(Embodiment 1)
1A to 1D are a light emitting device 1 according to the first embodiment.
In the present embodiment, the molding member 10 is made of resin and has a bottom surface 16 that is a surface (mounting surface) that faces the substrate when mounted on the substrate, and an upper surface 17 that faces the bottom surface 16. In addition, the surface on which the concave portion 15 in which the light emitting element 2 is accommodated is the front surface 14, and the first notch portion 11 is formed on the back surface 19 that faces the front surface 14. Further, the bottom surface 16 of the molding member 10 is formed with a stepped portion 13 that accommodates the main portion 21s of the outer lead portion 21, and the depth of the stepped portion 13 is substantially the same as the thickness of the metal plate constituting the outer lead portion. It has become. Here, the main portion 21 s of the outer lead portion 21 refers to a portion excluding the first end portion 21 r and the second end portion 21 t, that is, a portion bent along the bottom surface 16 of the molding member 10.

  In the light emitting device of the embodiment, a part of each inner lead portion 4 of the lead frame is exposed on the bottom surface of the recess 15 provided in the molding member 10. The light emitting element 2 is mounted on the bottom surface of the recess 15, and the negative electrode of the light emitting element 2 is electrically connected to one of the exposed inner lead portions 4, and the positive electrode of the light emitting element 2 is electrically connected to the other.

  The outer lead portions 21 projecting from the bottom surface 16 of the molded member 10 are each composed of a main portion 21s and two end portions 21t and 21r, and are bent so that the main portion 21s can be accommodated in the stepped portion 13, and further The first end 21 r is bent along the first notch 11, and the second end 21 t is bent along the side surface 18. Thus, in this embodiment, the place which arrange | positions the outer lead part 21 can be increased, and the surface area of an outer lead part can be increased. Thereby, the heat dissipation of an outer lead part can be improved and the heat dissipation of a light-emitting device can be improved. In the present embodiment, since the main portion 21s is disposed so as to be accommodated in the step portion 13 having a depth substantially the same as the thickness of the outer lead portion, the outer surface (grounding surface) and the bottom surface 16 ( The portion excluding the concave portion 13) can be positioned substantially on the same plane, and stable mounting is possible.

  In the present embodiment, the main portion 21s of the outer lead portion has a branch point and extends in the opposite direction with the same width. However, the present invention is not limited to this, for example, more heat dissipation. In order to improve the property, the main portion 21s of the outer lead portion may be shaped to gradually expand toward the two end portions 21r and 21t.

(1st notch)
As shown in FIG. 1, the first cutout portions 11 are formed in pairs on a back surface 19 that faces a front surface 14 provided with a recess 15 in which the light emitting element 2 can be placed.
The pair of first cutout portions 11 are on the back surface 19 of the molding member 10 and are formed symmetrically with respect to the vertical bisector of the back surface 19 when viewed from the top surface 17 and at a position closer to the axis. I can do it. By forming it symmetrically with respect to the axis, the production efficiency of the light emitting device is good.
The first notch 11 is formed at the above position, and the end of the outer lead 21 is disposed along the first notch 11, thereby reducing the distance between the ends of the outer lead 21. The surface area of the outer lead portion 21 can be increased without reducing the size. Thereby, the heat dissipation of the outer lead portion 21 can be improved while keeping the distance between the end portions of the outer lead portion 21 at a certain distance or more so as not to cause a short circuit. In other words, the distance between the pair of first cutout portions 11 is set so that the distance between the ends of the outer lead portions is not maintained when the outer lead portions are disposed.

A width W1 of the first notch 11 provided on the back surface 19 of the molding member 10 is formed wider than the thickness of the first end 21r. Further, the shape of the first cutout portion 11 may be any shape as long as the first end portion is disposed. The depth of the first notch 11 is preferably substantially the same width as the first end 21r so that the first end 21r does not protrude from the outermost shape when viewed from the back surface 19 of the molding member 10.
In addition, you may form a notch part in a back surface separately from the 1st notch part 11 in which a 1st edge part is arrange | positioned.

(side)
The side surfaces are adjacent to both the front surface 14 and the bottom surface 16 of the molded member, as shown in FIG. 1A. In FIG. 1A, the side surface is inclined from the front side toward the back surface 19 direction, but may not be inclined.

  Subsequently, a light emitting device according to an embodiment of the present invention different from that of Embodiment 1 will be described.

(Embodiment 2)
2A and 2B are the light emitting device 100 according to the second embodiment.
In the present embodiment, the molding member 110 has a second cutout portion 112 on the back surface 119 side of the side surface 118, and the outer lead portion 121 is a first bent along the first cutout portion 111 of the molding member 110. It has an end 121r and a second end 121t that is bent along the second notch 112.

(2nd notch)
Further, as shown in FIG. 2A, the second notch is on the side surface 118 adjacent to both the front surface 114 and the bottom surface 116, and is formed on the back surface 119 side of the side surface 118. In addition, the molded member 110 has a second notch 112, and the second end 121 t is bent along the second notch 112, so that the bent second end 121 t is connected to the back surface 119. It can be prevented from protruding from the side surface 118.

The width W2 of the second notch 112 is preferably equal to or greater than the thickness of the outer lead 121. This is because the second end portion 121t can be prevented from protruding from the outermost shape when viewed from the back surface 19 and the side surface 18 of the molded member. The shape of the second notch is a quadrangular prism in FIG. 2A, but may be any shape.
The first notch and the second notch are on the back surface 19 and are formed so that the first notch and the second notch do not contact or overlap each other.

The above points are different from the first embodiment, and the other points are the same as in the first embodiment. Also in the light emitting device of the second embodiment, the same effect as the light emitting device of the first embodiment described above can be obtained.

Hereinafter, the manufacturing method of the light-emitting device of this embodiment is demonstrated, referring FIG. 3A-FIG. 3D.
First, a metal flat plate is punched and then plated to form a lead frame flat plate (not shown). The lead frame flat plate includes a pair of inner lead portions corresponding to each light emitting device, a lead frame portion formed by a portion that is later cut to become an outer lead portion, and leads for supporting a molding member that connects them ( Hereinafter, it is referred to as a support lead) is formed at a predetermined position.

  Next, as shown in FIG. 3A, the inner lead portion 4 and the support lead 305, and the portion that will later become the outer lead portion, are disposed between the mold dies 324 and 307 and sandwiched between the upper and lower mold dies 324 and 307. . At this time, the molds 324 and 307 are formed so that a cavity 319 corresponding to the shape of the light emitting device is formed when they are combined. When the molds 324 and 307 are combined, a pair of inner leads The portion 4, the support lead 305, and the portion that will later become the outer lead portion are positioned at predetermined positions in the cavity 319, and are sandwiched between the mold dies 324 and 307. The tip of the support lead 305 is embedded in the side surface of the molding member until the molding member is detached. Further, the upper mold 324 is provided with a protrusion 303 corresponding to the shape of the recess 15 of the light emitting device.

  Subsequently, as shown in FIG. 3B, after the upper and lower molds are aligned, the molding material 320 is injected into the cavity 319 from the material injection gate 306 of the lower mold 307. Next, as shown in FIG. 3C, the molding material 320 injected into the cavity 319 is cured, and as shown in FIG. 3D, the lower mold 307 is removed first, and then the upper mold 324 is removed.

  The lead frame flat plate 128 in which the molding member 10 as shown in FIG. 4 is molded is obtained by the series of steps shown in FIGS. 3A to 3D described above.

As shown in FIG. 4, the molding member 10 has a recess 15 formed in the first side surface 14, and a part of the inner lead portion 4 is exposed on the bottom surface of the recess 15. 4 is connected to a portion to be the outer lead portion 21 later. Further, the support lead 305 is embedded in the side surface 18 of the molding member 10. That is, at this stage, the molding member 10 is supported on the lead frame flat plate 128 by the portion that becomes the outer lead portion 21 and the support lead 305.

  The concave portion 15 of the molding member 10 has a shape in which the light of the light emitting element 2 mounted on the bottom surface of the concave portion is easily extracted from the first side surface 14 side, for example, gradually from the bottom surface toward the first side surface 14 side. It is preferable that the side wall has an inclined surface so as to spread.

  As described above, the light emitting element 2 is mounted in the recess 15 of the molding member 10 with the molding member 10 supported by the lead frame flat plate 128. The light emitting element 2 may be mounted on one inner lead portion 4 (shown in FIG. 4) or directly on the resin surface.

  After mounting the light emitting element 2 in the recess 15, the positive and negative electrodes of the light emitting element 2 and the inner lead portion 4 are electrically connected by the conductive wires 22. Further, instead of the conductive wire, flip chip mounting (face-down mounting) may be performed using a conductive member.

  Thereafter, the recess 15 of the molded member 10 is filled with a sealing member, and the light emitting element 2 and the conductive wire 22 or the conductive member are sealed.

  And the part used as the outer lead part 21 is cut | disconnected from the lead frame flat plate 128 in the position of the broken line A of FIG.

  Then, the two end portions 21t and 21r that are part of the outer lead portion 21 at the position of the solid line B are bent along the bottom surface 16 in the direction of the back surface 19 of the molding member 10 as shown in FIG. The first end 21r is disposed in the first notch 11, and the second end 21t is disposed in the second notch 112 as shown in the side surface 18 of the molding member or FIG. 2B. By taking such a form, the place which arrange | positions an outer lead part can be increased and the surface area of an outer lead part can be increased. Thereby, the heat dissipation of an outer lead part can be improved and the heat dissipation of a light-emitting device can be improved. At this time, as shown in FIG. 4, the molding member 10 is supported on the lead frame flat plate by the support lead 305, but the molding member 10 is not inclined and detached from the lead frame flat plate 128 due to the force applied during cut forming. Thus, it is preferable to use a jig for holding the molding member 10.

  Finally, by removing the support lead 305, the light emitting device 1 as shown in FIG. 1 can be obtained.

  Below, each structural member of the light-emitting device concerning this embodiment is explained in full detail.

(Molded material)
As shown in FIG. 1, the molded member in the present invention has a first cutout portion 11 on the back surface 19. Further, as shown in FIG. 2, the second cutout portion 112 may be provided on the back surface 119 side of the side surface 118. The molding member includes a concave portion on which the light emitting element can be placed on the first side surface, functions as a support for fixing and holding the inner lead portion and the outer lead portion, and has a function of protecting the light emitting element and the like from the external environment.

  The molding material of the light-emitting device used in the present invention is not particularly limited, and any conventionally known thermoplastic resin such as liquid crystal polymer, polyphthalamide resin, polybutylene terephthalate (PBT) can be used. In addition, conventionally known thermosetting resins can also be used. In particular, when a semi-crystalline polymer resin containing a high melting point crystal such as a polyphthalamide resin is used, a sealing member that can be provided inside the recess and a light guide plate that can be retrofitted with a large surface energy. A molded member having good adhesion to the above can be obtained. Thereby, it can suppress that peeling generate | occur | produces in the interface of the shaping | molding member and sealing member in a cooling process in the process of filling and hardening a sealing member. Moreover, in order to reflect the light from a light emitting element efficiently, white pigments, such as a titanium oxide, can be mixed in a shaping | molding member.

(Light emitting element)
The light emitting element is usually a semiconductor light emitting element, and any element may be used as long as it is an element called a so-called light emitting diode. For example, a laminated structure including an active layer is formed on a substrate by various semiconductors such as a nitride semiconductor such as InN, AlN, GaN, InGaN, AlGaN, InGaAlN, a III-V compound semiconductor, and a II-VI compound semiconductor. What was formed is mentioned.

  In the light emitting device of the present invention, the number of light emitting elements may be one, or a plurality of light emitting elements may be mounted. In this case, in order to improve luminous intensity, a plurality of light emitting elements that emit the same light emission color may be combined. Further, for example, color reproducibility can be improved by combining a plurality of light emitting elements having different emission colors so as to correspond to RGB.

  As shown in FIG. 1B, these light emitting elements are mounted on the bottom surface of the recess 15 of the molding member 10 or the surface of the inner lead portion 4 by a joining member (not shown). In the case of a light emitting element formed by growing a nitride semiconductor on an insulating substrate (such as a sapphire substrate), for example, an epoxy resin or silicone can be used as such a bonding member. In consideration of deterioration from light and heat from the light emitting element, the back surface of the light emitting element is plated with Al, solder such as Au-Sn eutectic, brazing material such as low melting point metal, conductive paste, etc. as a joining member. It may be used. Furthermore, in the case of a light emitting device comprising a conductive substrate (such as GaAs) and having electrodes formed on both sides, such as a light emitting device that emits red light, it is mounted with a conductive paste such as silver, gold, or palladium. The

  In the light emitting device of the present invention, a protective element may be mounted in addition to the light emitting element. The protective element may be mounted in a recess where the light emitting element is placed, or may be mounted by forming another recess in the molded member. It may be mounted on the back surface of the inner lead portion on which the light emitting element is mounted, covered with a molding material, and formed integrally with the molding member. Further, the number of protective elements may be one, or two or more. Here, the protective element is not particularly limited, and may be any known element mounted on the light emitting device.

(Lead frame)
As shown in FIG. 1B, the lead frame includes an inner lead portion 4 that is at least partially embedded in the molding member 10 and an outer lead portion 21 that protrudes from the bottom surface 16 of the molding member 10.
The lead frame is an electrode for electrically connecting to the light emitting element, and may be substantially plate-shaped, and may be corrugated plate-shaped or plate-shaped having irregularities. The thickness may be uniform, or there may be a part that is thick or thin. The width is not particularly limited, but is preferably wider because the heat dissipation is improved. The material is not particularly limited, and it is preferably formed of a material having a relatively large thermal conductivity. By forming with such a material, heat generated from the light-emitting element can be efficiently released. For example, a material having a thermal conductivity of about 200 W / (m · K) or more, a material having a relatively large mechanical strength, or a material that can be easily stamped or etched is preferable. Specific examples include metals such as copper, aluminum, gold, silver, tungsten, iron and nickel, and alloys such as iron-nickel alloy and phosphor bronze. Further, it is preferable that the surface of the lead frame is subjected to reflection plating in order to efficiently extract light from the light emitting element to be mounted. The glossiness of the plating surface is preferably in the range of 0.2 to 2.0 in terms of light extraction efficiency and manufacturing cost.

(Outer lead part)
The outer lead portion is provided to supply electricity from the outside to the light emitting element placed in the recess of the light emitting device. In the light emitting device of this embodiment, the outer lead portion has two end portions, each having the same width and extending in the opposite direction, and the two end portions are the first notch portion and the side surface or the second notch portion. It is preferable to bend along the part. By taking such a form, the surface area of an outer lead part can be increased and an outer lead part with high heat dissipation can be obtained. Therefore, the heat generated from the light emitting device can be radiated well. Note that three or more end portions may be provided.
And although a part of outer lead part may protrude from the outermost shape seeing from the back surface 19 and the side surface 18 of a shaping | molding member, it is more preferable not to protrude.

(Inner lead)
The inner lead portion is disposed inside the light emitting device, and the outer lead portion is provided to supply electricity obtained from the outside to the light emitting element.

(Conductive wire)
As shown in FIG. 1B, the conductive wire electrically connects the positive electrode and the negative electrode of the light emitting element to the inner lead portion 4. The conductive wire is required to have good ohmic properties, mechanical connectivity, electrical conductivity, and thermal conductivity with the electrode of the light emitting element. The thermal conductivity is ^{0.01cal / (s) (cm 2} ) (℃ / cm) or more preferably preferably ^{0.5cal / (s) (cm 2} ) (℃ / cm) or more. In consideration of workability and the like, the diameter of the conductive wire is preferably Φ10 μm or more and Φ45 μm or less. From the viewpoint of securing the light emitting area of the light emitting element and ease of handling, Φ35 μm or less is more preferable. Specific examples of such conductive wires include conductive wires using metals such as gold, copper, platinum, and aluminum, and alloys thereof.

  The light emitting device of the present invention can be used for a liquid crystal backlight light source, various indicator light sources, panel meters, indicator lamps, surface light emitting switches, optical sensors, and the like.

It is the perspective view which looked at the light-emitting device of embodiment concerning this invention from diagonally upward. It is a front view of FIG. 1A. It is the perspective view which looked at FIG. 1A from diagonally downward. It is a side view of FIG. 1A. It is the perspective view which looked at another light-emitting device which is embodiment of this invention from diagonally upward. It is the perspective view which looked at FIG. 2A from diagonally downward. It is sectional drawing which shows a mode when an upper and lower metal mold | die is match | combined when manufacturing the light-emitting device of embodiment which concerns on this invention. It is sectional drawing which shows a mode immediately after inject | pouring the molding material in the cavity of a metal mold | die when manufacturing the light-emitting device of embodiment. It is sectional drawing which shows a mode when the gate after inject | pouring a molding material in the cavity of a metal mold | die is cut off when manufacturing the light-emitting device of embodiment. It is sectional drawing which shows a mode when removing an upper metal mold | die when manufacturing the light-emitting device of embodiment. It is a top view which shows a structure when the light-emitting device of embodiment is taken out from a metal mold | die after shaping | molding. It is a front view for demonstrating the conventional side light emission type light-emitting device.

Explanation of symbols

  2 Light emitting element, 10, 110 Molded member, 11, 111 First notch, 15 Recess, 16, 116 Bottom, 14, 114 Front, 19, 119 Back, 18, 118 Side, 21, 121 Outer lead, 21r 121r 1st end part, 21t, 121t 2nd end part, 4 inner lead part, 305 support lead, 22 conductive wire, 128 lead frame flat plate, 307, 324 mold die, 319 cavity, 320 molding material.

Claims (5)

A molding member having a recess for mounting the light emitting element on the front surface;
A light emitting device having an inner lead portion embedded in the molding member and a positive and negative lead frame having an outer lead portion protruding from the bottom surface of the molding member,
The molded member is
(A) a pair of first cutout portions for holding the outer lead portion of the positive lead frame and the outer lead portion of the negative lead frame at a predetermined distance or more on the back surface facing the front surface ;
(B) having a second cutout portion on the back surface side of the side surface connecting the front surface and the back surface ;
(C) The first notch and the second notch are formed separately from each other,
Wherein each outer lead portion, possess a first end which is folded along said first notch portion, and a second end portion which is bent along said second cut-out portion,
The bottom surface has a stepped portion that accommodates a main portion excluding the first end portion and the second end portion of the bent outer lead portion, and the outer surface of the main portion and the bottom surface of the bottom portion A light emitting device in which a portion excluding a stepped portion is located on the same plane .   2. The light emitting device according to claim 1, wherein the main portion has a branch point and extends in the opposite direction, and the extended tip portions are the first end portion and the second end portion, respectively. .   The light emitting device according to claim 1, wherein the main part extends toward the first end and the second end.   The light emitting device according to any one of claims 1 to 3, wherein the first notch has a quadrangular prism shape.   5. The light emitting device according to claim 1, wherein the first notch has a depth at which the first end portion does not protrude from the outermost shape when viewed from the back surface of the molding member.

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