WO2008038997A1

WO2008038997A1 - Light emitting diode package employing leadframe with plated layer of high brightness

Info

Publication number: WO2008038997A1
Application number: PCT/KR2007/004702
Authority: WO
Inventors: Nam Young Kim; Tae Kwang Kim; Kyoung Bo Han; Myung Hee Lee; Ji Seop So
Original assignee: Seoul Semiconductor Co., Ltd.
Priority date: 2006-09-27
Filing date: 2007-09-27
Publication date: 2008-04-03

Abstract

A light emitting diode package employing a leadframe provided with a high glossy plated layer is disclosed. The package includes a leadframe having a first lead terminal and a second lead terminal spaced apart from the first lead terminal. A package body supports the leadframe and has an opening for exposing the first and second lead terminals. Meanwhile, a high glossy plated layer is positioned on at least a surface of the first lead terminal exposed through the opening. Further, a semi glossy plated layer is positioned on at least a surface of the second lead terminal exposed through the opening portion. Accordingly, the reflectivity of the first lead terminal may be increased without reducing the adhesion between the second lead terminal and the boding wire, thereby increasing the light emission efficiency of the light emitting diode package.

Description

LIGHT EMITTING DIODE PACKAGE EMPLOYING LEADFRAME WITH PLATED LAYER OF HIGH BRIGHTNESS

Technical Field

[1] The present invention relates to a light emitting diode package, and more specifically, to a light emitting diode package employing a leadframe with a high glossy plated layer. Background Art

[2] Generally, a light source system using a light emitting diode chip has been formed by mounting a light emitting diode chip into various kinds of packages depending on their usages to be used. Specifically, in order to increase the light emission intensity within a desired viewing angle, a package in which a light emitting diode chip is mounted in a recess region of a package body encompassing a leadframe has been prevailingly used. As an example of such a package, there is a top-view type light emitting diode package or a side-view type light emitting diode package.

[3] Figs. 1 and 2 are plan and perspective views illustrating a conventional side-view type light emitting diode package, respectively, and Fig. 3 is a sectional view taken along a dashed dotted line A-A of Fig. 1.

[4] Referring to Figs. 1 to 3, the side-view type light emitting diode package includes a pair of lead terminals, i.e., first and second lead terminals 11 and 13. The first and second lead terminals 11 and 13 are formed out of a leadframe manufactured with a phosphor bronze plate, and a surface thereof is formed with a silver (Ag) plated layer 14 for increasing the light reflectivity. A Ni plated layer 12 is primarily interposed between the silver plated layer 14 and the leadframe to increase the adhesive property of the silver plated layer. The first and second lead terminals 11 and 13 are supported by a package body 15. The package body 15 is generally formed by insert- molding the lead terminals with polyphthalamide (PPA).

[5] The package body 15 has an opening 16 for exposing the first and second lead terminals 11 and 13. The first and second lead terminals 11 and 13 are positioned on a bottom of the opening 16 and spaced apart from each other in the opening 16. Further, each of the first and second lead terminals 11 and 13 protrudes to the outside of the package body 15 in order to be electrically connected to an external power supply. The first and second lead terminals 11 and 13 which protrude outward may have various shapes and be bent with various shapes. Figs. 1 and 2 show the first and second lead terminals 11 and 13 which are bent from a lower surface of the package body 15 to side surfaces thereof to implement a surface mounting. [6] A light emitting diode chip 17 is mounted onto the first lead terminal 11 in the opening 16 to be electrically connected to the first lead terminal 11, and electrically connected to the second lead terminal 13 through a bonding wire. The opening 16 may be filled with a light- transmittable resin 23, and phosphors may be contained in the light-transmittable resin.

[7] The conventional side-view type light emitting diode package is provided with the opening 16 of an elongated shape, and sidewalls, specifically sidewalls in a major axis are formed to be inclined to widen a visible angle in the major axis. Accordingly, a side-view type light emitting diode package suitable to a backlight for a display may be provided, and a side-view type light emitting diode which emits white light may be provided by the suitable selection of a light emitting diode chip and a phosphor.

[8] However, the conventional light emitting diode package includes a leadframe, on a surface of which a semi glossy silver plated layer is formed in order to increase the adhesion of the bonding wire 19 for connecting the light emitting diode chip 17 and the second lead terminal 13. Accordingly, when the light emitted from the light emitting diode chip 17 is reflected by the semi glossy plated layers of the first and second lead terminals, the reflectivity is decreased, and as a result, the light emission efficiency is reduced.

[9] Meanwhile, in a case where a high glossy plated layer is formed on the leadframe, there is a problem in that the bonding wire 19 may be easily detached from the second lead terminal since the adhesion between the second lead terminal 13 and the bonding wire 19 is weak. Disclosure of Invention

Technical Problem

[10] An object of the present invention is to provide a light emitting diode package capable of improving reflectivity of a lead terminal without reducing the adhesion between the lead terminal and a bonding wire. Technical Solution

[11] The present invention for achieving the object provides a light emitting diode package employing a leadframe with a high glossy plated layer. The package includes a leadframe having a first lead terminal and a second lead terminal spaced apart from the first lead terminal. A package body supports the leadframe and has an opening for exposing the first and second lead terminals. Meanwhile, a high glossy plated layer is positioned on at least a surface of the first lead terminal exposed through the opening. Further, a semi glossy plated layer is positioned on a surface of the second lead terminal exposed through the opening. Accordingly, the reflectivity of the first lead terminal can be increased without reducing the adhesion between the second lead terminal and a bonding wire.

[12] Herein, the term "high glossy" is used to indicate that the reflectivity percentage of light, which is emitted from a light emitting diode chip, from a surface is equal to or larger than 90%, while the term "semi glossy" is used to indicate that the reflectivity percentage is smaller than 90%.

[13] Meanwhile, a semi glossy plated layer may be interposed between the first lead terminal and the high glossy plated layer. The semi glossy plated layer may be formed through the same process as the semi glossy plated layer positioned on the surface of the second lead terminal.

[14] Further, both the high glossy plated layer and the semi glossy plated layer may be a silver plated layer. Accordingly, the light emitted from the light emitting diode chip may be reflected with a high reflectivity to thereby increase the light emission efficiency.

[15] Meanwhile, an underlying plated layer may be interposed between the semi glossy plated layer and/or the high glossy plated layer and the leadframe. The underlying plated layer increases the adhesion between the semi glossy plated layer or the high glossy plated layer and the leadframe. The underlying plated layer may be made of Ni.

[16] Meanwhile, the light emitting diode package may further include a high glossy plated layer partially positioned on the surface of the second lead terminal.

[17] The semi glossy plated layer of the second lead terminal may be positioned on the high glossy plated layer of the second lead terminal. Such a semi glossy plated layer may be made of Ag or Au. Meanwhile, the high glossy plated layer of the second lead terminal may be made by plating with Ni.

[18] On the contrary, the high glossy plated layer of the second lead terminal may be positioned on the semi glossy plated layer of the second lead terminal. At this time, the semi glossy plated layer of the second lead terminal is exposed through the high glossy plated layer of the second lead terminal.

[19] Meanwhile, at least one light emitting diode chip is mounted on the first lead terminal, and a bonding wire connects the light emitting diode chip and the second lead terminal. At this time, the bonding wire is bonded to the semi glossy plated layer positioned on the surface of the second lead terminal. Accordingly, the adhesion between the bonding wire and the second lead terminal may not be reduced, and the reflectivity of light may be improved by means of the high glossy plated layer provided on the surface of the first lead terminal.

[20] Further, a semi glossy plated layer may be partially positioned on the surface of the first lead terminal, and another bonding wire may connect the light emitting diode chip and the semi glossy plated layer partially positioned on the surface of the first lead terminal. [21] The semi glossy plated layer partially positioned on the surface of the first lead terminal may be positioned on the high glossy plated layer of the first lead terminal. On the contrary, the semi glossy plated layer partially positioned on the surface of the first lead terminal may be positioned between the high glossy plated layer of the first lead terminal and the first lead terminal, and the high glossy plated layer of the first lead terminal may be partially positioned in order to expose the semi glossy plated layer.

Advantageous Effects

[22] According to the embodiments of the present invention, the light reflectivity of a lead terminal onto which a light emitting diode chip is mounted may be improved without reducing the adhesion of the boding wire, thereby increasing the light emission efficiency of a light emitting diode package.

Brief Description of the Drawings

[23] Fig. 1 is a plan view illustrating a conventional light emitting diode package.

[24] Fig. 2 is a perspective view illustrating the conventional light emitting diode package. [25] Fig. 3 is a sectional view taken along a dashed dotted line A-A of Fig. 1 to illustrate the conventional light emitting diode package. [26] Fig. 4 is a plan view illustrating a light emitting diode package according to an embodiment of the present invention. [27] Fig. 5 is a sectional view taken along a dashed dotted line B-B of Fig. 4 to illustrate the light emitting diode package according to the embodiment of the present invention. [28] Fig. 6 is a sectional view illustrating a light emitting diode package according to another embodiment of the present invention. [29] Figs. 7 and 8 are sectional views illustrating a method for forming a leadframe of the light emitting diode package according to the other embodiment of the present invention. [30] Fig. 9 is a sectional view illustrating a leadframe according to a further embodiment of the present invention. [31] Fig. 10 is a plan view illustrating a light emitting diode package according to a still further embodiment of the present invention.

Mode for the Invention [32] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided only for illustrative purposes so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the following embodiments but may be implemented in other forms. In the drawings, the widths, lengths, thicknesses and the like of elements may be exaggerated for convenience of illustration. Like reference numerals indicate like elements throughout the specification and drawings.

[33] Fig. 4 is a plan view illustrating a side-view type light emitting diode package according to an embodiment of the present invention, and Fig. 5 is a sectional view taken along a dashed dotted line B-B of Fig. 4.

[34] Referring to Figs. 4 and 5, the side-view type light emitting diode package includes a leadframe which has a pair of lead terminals, i.e., first and second lead terminals 51 and 53. The leadframe may be manufactured by punching a phosphor bronze plate.

[35] The first and second lead terminals 51 and 53 are supported by a package body 55.

The package body 55 may be formed by insert molding the first and second lead terminal 51 and 53. The package body 55 has an opening 58 for exposing the first and second lead terminals 51 and 53, and the opening 58 causes the first and second lead terminals 51 and 53 to be partially exposed.

[36] The first and second lead terminals 51 and 53 are positioned in the opening 58 to be spaced apart from each other. In addition, each of the first and second lead terminals 51 and 53 protrudes to the outside of the package body 55 in order to be electrically connected to an external power supply. The first and second lead terminals 51 and 53 which protrude outward may have various shapes and be bent with various shapes. Herein, there are shown the first and second lead terminals 51 and 53 which are bent from a lower surface of the package body 55 to side surfaces thereof to enable the surface mounting.

[37] Meanwhile, a semi glossy plated layer 54 is positioned on a surface of the second lead terminal 53 exposed through the opening portion. The semi glossy plated layer 54 may be formed on the entire surface of the second lead terminal 53. Further, an underlying plated layer 52 may be interposed between the semi glossy plated layer 54 and the second lead terminal 53. The underlying plated layer 52 may be formed by plating with Ni.

[38] Meanwhile, a high glossy plated layer 56 is positioned on at least a surface of the first lead terminal 51 exposed through the opening 58. Further, the semi glossy plated layer 54 may be interposed between the high glossy plated layer 56 and the first lead terminal 51, and the underlying plated layer 52 may be interposed between the semi glossy plated layer 54 and the first lead terminal 51. As shown in the figures, the high glossy plated layer 56 is formed on an upper surface of the first lead terminal 51 in order to reflect light, but it may be formed to extend onto a lower surface of the first lead terminal 51.

[39] The first and second lead terminals 51 and 53 having the plated layers 52, 54 and 56 may be formed as described below. Firstly, the underlying plated layer 52 and the semi glossy plated layer 54 are formed on the leadframe through the same method as the prior art. The underlying plated layer 52 may be conventionally formed by plating with Ni, while the semi glossy plated layer 54 may be formed of Ag through a conventional plating technique. Then, a mask layer is formed on the leadframe in order to expose at least a portion of an upper portion of the first lead terminal. The mask layer may be formed of, for example, photoresist, so that the mask layer may allow the semi glossy plated layer 54 on the surface of the first lead terminal to be exposed. Then, the high glossy plated layer 56 is formed on a surface of the first lead terminal 51. The high glossy plated layer 56 may also be formed by plating with Ag, and by controlling a current density or an addition agent such as brightener or the like which is added to a plating solution by using an electroplating technique. Accordingly, the high glossy plated layer 56 is formed on the first lead terminal 51 exposed by the mask layer. Then, by removing the mask layer, formation of the plated layers of the first and second lead terminals 51 and 53 is completed. Preferably, the high glossy plated layer 56 may be formed on the entire upper surface of the first lead terminal 51 exposed through the opening 58 of the package body 55.

[40] A light emitting diode chip 57 is mounted on the first lead terminal 51 and electrically connected to the second lead terminal 53 through a bonding wire 59. At this time, the bonding wire 59 is bonded to the semi glossy plated layer 54 of the second lead terminal 53, which maintains the same adhesion as the prior art.

[41] Meanwhile, a transparent resin 63 may be formed on the light emitting diode chip

57. The transparent resin may be formed in the opening 58 by potting liquid phase resin. The transparent resin may be formed of, for example, epoxy or silicone resin, and contain a phosphor for converting light emitted from the light emitting diode chip 57, for example, blue light, to yellow light. Accordingly, a side-view type light emitting diode package emitting white light may be provided. The light emitting diode chip 57 and the phosphor may be variously selected, so that the light having variable colors may be implemented.

[42] Further, if the light emitting diode chip is a 2 bonding chip, i.e., if two bonding wires are used to electrically connect the light emitting diode chip to the lead terminals, it is preferable that the high glossy plated layer 56 is also partially formed on the surface of the first lead terminal except for a portion to which the bonding wires are bonded. That is, the high glossy plated layer may be partially positioned so as to expose a region of the first lead terminal, and the bonding wire for connecting the first lead terminal and the light emitting diode chip may be connected to the exposed region. Further, the semi glossy plated layer may be exposed on a region of the first lead terminal, and the bonding wire may be connected to the exposed semi glossy plated layer. Accordingly, the adhesion of the bonding wire connected to the first lead terminal can be prevented from being reduced.

[43] Fig. 6 is a sectional view illustrating a side-view type light emitting diode according to another embodiment of the present invention.

[44] Referring to Fig. 6, as illustrated with reference to Fig. 5, the first and second lead terminals 51 and 53 are supported by a package body 50, and the package body 50 has an opening 58 (in Fig. 4) for exposing the first and second lead terminals 51 and 53. The first and second lead terminals 51 and 53 are positioned to be spaced apart from each other in the opening 58, and each of the first and second lead terminals 51 and 53 protrudes to the outside of the package body 50 in order to be electrically connected to an external power supply.

[45] Meanwhile, a first plated portion 74 is positioned on a surface of the second lead terminal 53. The first plated portion 74 may be formed by plating a portion of the second lead terminal 53 with metal for the purpose of adhesion of the bonding wire 59. Herein, the surface area and shape of the first plated portion 74 can be appropriately adjusted in consideration of the easiness of the wire bonding and the metal plating for the formation of the first plated portion. Meanwhile, it is preferable that the first plated portion 74 is made of metal, such as Ag or Au, which maintains an excellent adhesion of the bonding wire.

[46] Further, a second plated portion 75 which is a high glossy plated layer for increasing the light reflectivity is positioned on a region of the surface of the second lead terminal 53 except for the first plated portion 74. Meanwhile, the high glossy plated layer may also be on a surface of the first lead terminal 51. The second plated portion 75 is formed of high glossy metal in order to increase the light reflectivity, and, for example, may be formed with a high glossy metal such as Ni. The first plated portion 74 may be positioned on the second plated portion 75 as shown, but the present invention is not limited thereto. That is, the first plated portion 74 may be positioned under the second plated portion 75 or to the same level as the second plated portion 75. An embodiment in which the first plated portion 74 is positioned under the second plated portion 75 will be described later with reference to Fig. 9.

[47] Further, the first plated portion 74 is formed on an upper surface of the second lead terminal 53 for the purpose of adhesion of the bonding wire 59. Also, the first plated portion may be formed to extend toward a lower surface of the second lead terminal. In this case, the second plated portion 75 may be interposed between the second lead terminal 53 and the first plated portion 74 on the lower surface of the second lead terminal 53.

[48] Figs. 7 and 8 are sectional views illustrating a leadframe fabrication method for forming the first and second lead terminals 51 and 53 of the side-view type light emitting diode package illustrated in Fig. 6. [49] Firstly, referring to Fig. 7, the second plated portion 75 is formed on the leadframe.

The second plated portion 75 may be formed by plating with a high glossy metal, generally Ni, to increase the light reflectivity efficiency. Then, a mask layer 80 is formed on the leadframe to at least partially expose the upper portion of the second lead terminal 53 for providing a region on which the bonding wire 59 is bonded. The mask layer may be formed of, for example, photoresist, and the mask layer causes a portion of the second plated portion 75 on the surface of the second lead terminal 53 to be exposed.

[50] Referring to Fig. 8, the first plated portion 74 is formed on a surface of the second plated portion 75. The first plated portion 74 may be formed by plating with a metal for increasing the adhesion of the bonding wire 59, generally Ag or Au, and by adjusting the current density or the like using an electroplating technique. Accordingly, the first plated portion 74 is formed on the portion of the second lead terminal 53 exposed by the mask layer. Then, the mask layer is removed, whereby the plated layers of the first and second lead terminals 51 and 53 are completed.

[51] The light emitting diode chip 57 is mounted on the first lead terminal 51, and electrically connected to the first plated portion 74 of the second lead terminal 53 through the bonding wire 59. At this time, the bonding wire 59 is bonded to the first plated portion 74 of the second lead terminal 53, which maintains the same adhesion as the prior art.

[52] Meanwhile, as illustrated with reference to Fig. 5, the transparent resin 63 may be formed on the light emitting diode chip 57.

[53] Fig. 9 is a sectional view illustrating a leadframe according to a further embodiment of the present invention.

[54] Referring to Fig. 9, the underlying plated layer 52 which is plated metal such as Ni is positioned on the entire surfaces of the first and second lead terminals 51 and 53 exposed through the opening 58 (in Fig. 4) of the package body 50 (in Fig. 4), and the first plated portion 54, i.e., the semi glossy plated layer of metal such as Ag or Au, is positioned on the underlying plated layer 52. The underlying plated layer 52 and the first plated portion 54 are formed on the leadframe made of a phosphor bronze plate through the same plating technique as the prior art.

[55] A second plated portion 86 is positioned on a region of the first plated portion 54 positioned on the surface of the second lead terminal 53 except for a portion to which the bonding wire 59 is bonded. To this end, a mask layer is formed on the portion of the surface of the first plated portion 54 of the leadframe to which the bonding wire 59 of the second lead terminal 53 is bonded. The mask layer may be formed of, for example, photoresist, and a portion of the first plated portion 54 on the surface of the second lead terminal 53 is covered with the mask layer. Then, the second plated portion 86 may be formed on the portion of the first plated portion 54 exposed through the mask layer. The second plated portion 86 may be formed by plating with a metal, such as Ni or Ag, having the excellent light reflectivity efficiency through an electroplating technique by controlling a current density or an addition agent such as brightener which is added to a plating solution. Accordingly, the second plated portion 86 is formed on a region except for a portion of the second lead terminal 53 covered with the mask layer. Then, by removing the mask layer, the plated layers of the first and second lead terminals 51 and 53 are completed.

[56] In this embodiment, a side-view type light emitting diode package has been described as an example. However, the present invention is not limited thereto, but may be applied to all kinds of light emitting diode packages employing leadframes having the first and second lead terminals.

[57] Meanwhile, it is described in this embodiments that the light emitting diode chip is a 1 bonding chip, i.e., the light emitting diode chip is electrically connected on the first lead terminal, and electrically connected to the second lead terminal by one bonding wire. However, the present invention is not limited thereto, but may be also applied to a case where the light emitting diode chip is a 2 bonding chip, i.e., two bonding wires are used to electrically connect the light emitting diode chip to the respective lead terminals. Such a case will be described in detail hereinafter with reference to Fig. 10.

[58] Fig. 10 is a plan view illustrating a side-view type light emitting diode package according to a still further embodiment of the present invention. The light emitting diode package according to this embodiment corresponds to a case where a light emitting diode chip is a 2 bonding chip, i.e., two bonding wires are used to electrically connect the light emitting diode chip to the respective lead terminals. Therefore, since the other descriptions except for the above features are identical with those of the previous embodiments, the detailed descriptions thereof will be omitted herein.

[59] Referring to Fig. 10, in a case where two bonding wires are used to electrically connect the light emitting diode chip 57 to the respective terminals 51 and 53, a third plated portion 94 of a metal such as Ag or Au with an excellent adhesion of the bonding wire is partially formed on a portion of the surface of the first lead terminal 51 to which another bonding wire 59a is bonded, as well as on the surface of the second lead terminal 53. The third plated portion 94 may be formed on the second plated portion 75 like the first plated portion 74 illustrated with reference to Fig. 6, or may be formed from the first metal plated portion 54 exposed through the second plated portion 86 as illustrated with reference to Fig. 9.

[60] Meanwhile, a fourth plated portion 75 of a high glossy plated layer is formed on a region except for the portion on which the third plated portion 94 is formed, using a metal having an excellent light reflectivity such as Ni or Ag. Like the second plated portion 75 illustrated with reference to Fig. 6 or the second plated portion 86 illustrated with reference to Fig. 9, the fourth plated portion 75 may be also formed on or under the third plated portion 94 or at the same level as the third plated portion 94. [61] The bonding wire 59a for connecting the first lead terminal 51 and the light emitting diode chip is bonded to the third plated portion 94, so that the adhesion of the bonding wire connected to the first lead terminal may be prevented from being reduced.

Claims

[1] A light emitting diode package, comprising: a leadframe having a first lead terminal and a second lead terminal spaced apart from the first lead terminal; a package body supporting the leadframe, the package body having an opening for exposing the first and second lead terminals; a high glossy plated layer positioned on at least a surface of the first lead terminal exposed through the opening portion; and a semi glossy plated layer positioned on at least a surface of the second lead terminal exposed through the opening portion.

[2] The light emitting diode package as claimed in claim 1, further comprising a semi glossy plated layer interposed between the first lead terminal and the high glossy plated layer.

[3] The light emitting diode package as claimed in claim 1, wherein the high glossy plated layer and the semi glossy plated layer are silver plated layers.

[4] The light emitting diode package as claimed in claim 1, further comprising a underlying plated layer interposed between the leadframe and at least one of the semi glossy plated layer and the high glossy plated layer.

[5] The light emitting diode package as claimed in claim 1, further comprising a high glossy plated layer partially positioned on a surface of the second lead terminal.

[6] The light emitting diode package as claimed in claim 5, wherein the semi glossy plated layer of the second lead terminal is positioned on the high glossy plated layer of the second lead terminal.

[7] The light emitting diode package as claimed in claim 6, wherein the semi glossy plated layer of the second lead terminal is made of Ag or Au, and the high glossy plated layer of the second lead terminal is made of Ni.

[8] The light emitting diode package as claimed in claim 5, wherein the high glossy plated layer of the second lead terminal is positioned on the semi glossy plated layer of the second lead terminal.

[9] The light emitting diode package as claimed in any one of claims 1 to 8, further comprising: at least one light emitting diode chip mounted on the first lead terminal; and a bonding wire for connecting the light emitting diode chip and the second lead terminal, the bonding wire being bonded to the semi glossy plated layer positioned on the surface of the second lead terminal.

[10] The light emitting diode package as claimed in claim 9, further comprising: a semi glossy plated layer partially positioned on a surface of the first lead terminal; and another bonding wire for connecting the light emitting diode chip and the semi glossy plated layer of the first lead terminal.

[11] The light emitting diode package as claimed in claim 10, wherein the semi glossy plated layer partially positioned on the surface of the first lead terminal is positioned on the high glossy plated layer of the first lead terminal.

[12] The light emitting diode package as claimed in claim 10, wherein the semi glossy plated layer partially positioned on the surface of the first lead terminal is positioned between the high glossy plated layer of the first lead terminal and the first lead terminal, and the high glossy plated layer of the first lead terminal is partially positioned in order to expose the semi glossy plated layer.