KR20120080306A - Led package and its manufacturing method - Google Patents

Abstract

PURPOSE: An LED package and a manufacturing method thereof are provided to improve productivity of the LED package by omitting or reducing the number of process of wire bonding. CONSTITUTION: An LED chip(120) comprises a p-type electrode(121) and an n-type electrode(122). The p-type electrode is located on a p-type semiconductor layer. The n-type electrode is located on an n-type semiconductor layer. A sub mount(110) comprises a conductive pattern(112), a first electrode pad(114a), and a second electrode pad(114b). Both ends of the conductive pattern are respectively connected with the first electrode pad and the second electrode pad. A bump(130) interlinks the n-type electrode and the conductive pattern. The conductive pattern comprises transparent metal or a metallic oxide.

Description

LED package and its manufacturing method {LED PACKAGE AND ITS MANUFACTURING METHOD}

The present invention relates to a light emitting diode (LED) package, and more particularly, to improve productivity, and satisfactorily satisfy various characteristics that determine the performance of the LED package, that is, heat dissipation characteristics and light emission characteristics. Relates to an LED package.

Recently, a light emitting diode (LED) is widely used in various fields such as a display device or a backlight module thereof, or an indoor / outdoor lighting device. LED (Light Emitting Diode) means a solid light emitting device consisting basically of a junction of semiconductors. When voltage is applied to the LED, electrons and holes are combined to emit energy corresponding to the band gap of the semiconductor in the form of light. These LEDs have many advantages, such as high power characteristics at low current requirements, fast responsiveness, long life, and rigid package structure.

The LED package is made by embedding the LED chip in the package body. The package body is at least partially translucent so that the light generated from the LED chip can be sent out. Generally, an LED chip is mounted on the bottom of the cavity of the non-transparent reflector (or housing).

Typically, the LED package is mounted on a substrate such as a printed circuit board (PCB) by, for example, a conductive adhesive such as solder paste. Conventional LED packages have lead terminals for applying a voltage to the LED chip, which lead terminals are electrically connected to an electrical circuit in the substrate by a conductive adhesive material. On the other hand, heat is generated during the light emitting operation of the LED chip, which may degrade the performance of the LED package and reduce the lifetime of the LED package. In particular, since high power is applied to a high output LED package, the degradation of performance and lifetime by heat is more serious. In addition, the wire bonding process for electrically connecting the electrodes and the lead terminals of the LED chip is complicated, in particular, when a plurality of LED chips are embedded in one LED package, productivity is greatly reduced by the wire bonding process. This is a major obstacle in integrating a plurality of LED chips in series or in parallel.

Accordingly, an object of the present invention is to provide an LED package that can satisfactorily satisfy various characteristics that determine the performance of the LED package, that is, heat dissipation characteristics, light emission characteristics, and / or integration, etc. together with the improvement of the productivity. will be.

According to one aspect of the invention, there is provided an LED package comprising a base mount and an LED element mounted on the base mount, the LED element is bonded on the base mount, the n-type opposite the junction position An LED chip having an electrode and a p-type electrode, and a conductive pattern formed on one surface thereof, and a light-transmissive submount in which the conductive pattern is electrically connected to the n-type electrode and the p-type electrode by flip chip bonding with the LED chip. It includes.

Preferably, the conductive pattern includes a transparent metal or metal oxide, and more preferably, the conductive pattern includes indium tin oxide (ITO).

Preferably, the submount includes electrode pads connected to the conductive pattern on a surface opposite to a surface on which the conductive pattern is formed.

Preferably, the LED device includes a plurality of LED chips flip-chip bonded to the submount, the plurality of LED chips may be connected in series or in parallel by the conductive pattern.

Preferably, the base mount may be a heat radiating substrate made of metal or ceramic material. Preferably, the reflector is installed to be bonded to the base mount with a cavity surrounding the periphery of the LED element, the protective member may be disposed to cover the cavity.

Preferably, the protection member may include a plurality of lens shapes corresponding to each of the plurality of LED chips. Preferably, the submount may comprise glass or quartz material.

According to another aspect of the present invention, there is provided a method of manufacturing an LED package, the method comprising the steps of: (a) preparing a transmissive submount having a conductive pattern formed on one surface; and (b) at least one on the submount. Flip chip bonding the LED chip to produce an LED device having a submount on the top surface of the LED chip; and (c) bonding the bottom surface of the LED device onto a base mount. Preferably, the step (b) uses a laser as a heat source for the flip chip bonding.

According to embodiments of the present invention, the number of processes of wire bonding can be reduced or eliminated to improve the productivity of the LED package, and various characteristics that determine the performance of the LED package, that is, both heat dissipation and light emission characteristics It is possible to improve it and to integrate the plurality of LED chips in the light-transmissive submount having the conductive pattern, there is an advantage that the integration characteristics are improved.

1 is a cross-sectional view showing an LED device according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of an LED package to which the LED device shown in FIG. 1 is applied.
3 and 4 are views for explaining the process of manufacturing the LED package shown in FIG.
5 and 6 are cross-sectional views for explaining the LED package according to another embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, the embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art, the following examples can be modified in various other forms, the scope of the present invention Is not limited to the following examples.

1 is a cross-sectional view showing an LED device according to an embodiment of the present invention, Figure 2 is a cross-sectional view showing an LED package to which the LED device shown in Figure 1 is applied, Figures 3 and 4 are shown in FIG. Figures for explaining the process of manufacturing the LED package. 5 and 6 are cross-sectional views illustrating LED packages according to another embodiment of the present invention.

As shown in FIG. 1, the LED device 10 according to an exemplary embodiment of the present invention includes a submount 110 and a plurality of LED chips 120 flip-chip bonded to the submount 110. . In addition, the LED device 10 may include conductive bumps 130 such as solder balls as a bonding member for the flip chip bonding.

Although not shown in detail, the LED chip 120 includes an p-type semiconductor layer and an n-type semiconductor layer, and an active layer formed between the p-type semiconductor layer and the n-type semiconductor layer to generate light by recombination of electrons and holes. Include. In addition, the LED chip 120 includes a p-type electrode 121 and an n-type electrode 122, the p-type electrode 121 is located on the p-type semiconductor layer side, the n-type electrode 122 is It is located in the n-type semiconductor layer side. The LED chip 120 may have a semiconductor growth substrate such as a sapphire substrate on the opposite surface of the p-type electrode 121 and the n-type electrode 122, that is, the lower surface. As described below, the lower portion of the LED chip 120 is bonded onto the base mount. When the base mount is conductive, it is preferable that the LED chip 120 and the base mount are insulated from each other. LED chips may be more preferred for the present invention.

The submount 110 is made of glass or quartz material, and includes a conductive pattern 112 formed on a bottom surface thereof, and first and second electrode pads 114a and 114b formed on an upper surface thereof. . Although not shown in detail, both ends of the conductive pattern 112 pass through the side surface of the submount 110 or through the submount 110 to pass through the first electrode pad 114a and the second electrode pad 114b. Respectively). The conductive pattern 112 is preferably formed of a transparent conductive material, in particular, a transparent metal or a transparent metal oxide so as not to block a path of the light emitted from the LED chip 120. In this embodiment, indium tin oxide (ITO) having good electrical characteristics and transparency is used as the material of the conductive pattern 112. Although not shown, the first and second electrode pads 114a and 114b are electrically connected to an external power source by, for example, a wiring means such as a bonding wire. In the present embodiment, the conductive pattern 112 may connect the plurality of LED chips 120 in series or in parallel. To this end, the conductive pattern 112 may be divided to correspond to the LED chip 120.

 According to a preferred embodiment, the first and second electrode pads 114a and 114b are located on the opposite side of the surface on which the conductive pattern 112 is located, that is, on the upper surface of the submount 110, It may also be considered to place the first and second electrode pads 114a and 114b on the surface where the conductive pattern 112 exists, that is, on the bottom surface of the submount 110.

The bumps 130, ie, solder balls, are electrically connected between the p-type electrode 121 and the conductive pattern 112 between the submount 110 and the LED chip 120, and the n-type electrode 122 and the conductive pattern. Connect between the patterns 112. Au: Sn or Ag: Sn may be used as the material of the bump 130. At this time, the flip chip process is preferably a solder ball melting method using a laser to improve the productivity.

Referring to FIG. 2, the LED package 1 includes the LED device 10 described above and a base mount 20 on which the LED device 10 is mounted. The base mount 20 may be a heat-dissipating substrate made of a metal or ceramic having good thermal conductivity so as to easily dissipate heat generated from the LED element 10 to the outside. In particular, a Cu substrate, an Al substrate, or a Si substrate may be used. It is good.

The LED device 10 is mounted on the base mount 20 by bonding the bottom surface of the LED chips 120 onto the base mount 20 by a reflow soldering process. By the above structure, the light emitted from the plurality of LED chips 120 is emitted upward through the light-transmissive submount 110 present thereon.

The reflector 30 is bonded to the base mount 20, and the reflector 30 includes a cavity 32 that surrounds the periphery of the LED device 10 as a whole. The cavity 32 has a cross-sectional shape of lower narrow light by an inclined inner wall surface, and a reflection layer 34 is formed on the inner wall surface by coating, for example. In addition, the LED package 1 includes a transparent protective member 40 covering at least an upper portion of the cavity 32 to protect the LED device 10 in the cavity. The protective material 40 may be a resin, glass or quartz having a light transmittance.

In this embodiment, the protective member 40 is made of a translucent plate structure coupled to the upper surface of the reflector 30, but as shown in FIG. 5, the protective member is filled in the cavity 32. The encapsulation material 40A formed of epoxy, silicon, or another resin material may be used. Also, as shown in FIG. 6, the protection member includes a lens member 40B including a plurality of lens-shaped portions 402 positioned directly on the LED chips 120 to correspond to the LED chips 120. ) May be included. Furthermore, an encapsulant 40A may be further formed in the cavity under the lens member 40B.

Meanwhile, the encapsulant 40A shown in FIGS. 5 and 6 includes a phosphor 404 for converting the wavelength of light emitted from the LED chip 120. The position at which the phosphor 404 is present should not be limited to the encapsulant, for example, the inner wall surface of the cavity of the reflector 30, inside or outside the lens member 40B, and moreover, the LED chip 120 or the like. May reside on submount 110. In particular, the light-transmissive submount 110 according to the present invention is advantageous in the application of the phosphor in the form that enables uniform coating of the phosphor and passes most of the light from one or more LED chips 120.

Now, a method of manufacturing an LED package according to the present invention will be described with reference to FIGS. 3 and 4.

Referring to FIG. 3, a transmissive submount 110 is first manufactured on a conductive pattern 112. Next, the solder balls or conductive bumps 130 are disposed so as to be appropriately between the conductive patterns 112 of the submount 110 and the electrodes 121 and 122 of the LED chip 120, and the laser, in particular, Nd By melting the solder ball using a -YAG laser, the LED chips 120 are flip-bonded on the submount 110. As a result, the LED element 10 is produced.

Referring to FIG. 4, the LED element 10 is mounted on a base mount 20 to which the reflector 30 is bonded by a bonding process by an adhesive layer. The reflector 30 is formed to have a cavity 32 in advance by punching (or pressing), and then bonded onto the base mount 20.

The LED element 10 is inverted in the opposite direction from the position shown in FIG. 3 so that the submount 110 faces upward and the LED chips 120 face downward. Next, the solder paste is present between the bottom surface of the LED chip 120 and the base mount 20, and the bottom surface of the LED chip 120 is bonded to the base mount 20.

Next, when the protective member covering the cavity 32 is formed, the manufacture of the LED package is completed. Before or during the foregoing processes, a means (eg, a lead terminal) for connecting the first and second electrode pads 114a and 114b to an external power source may be separately provided, or the first and second electrode pads may be provided. The bonding wires are connected to the 114a and 114b, and the bonding wires are directly drawn out to the outside or the bonding wires are drawn out to the outside through the lead terminal.

10: LED element 110: submount
121: p-type electrode 122: n-type electrode
120: LED chip 130: bump (solder ball)
20: base mount 30: reflector

Claims (12)

An LED package comprising a base mount and an LED element mounted on the base mount, wherein the LED element,
An LED chip bonded on the base mount, the LED chip having an n-type electrode and a p-type electrode on opposite sides of the bonding position;
A transmissive submount in which a conductive pattern is formed on one surface and the conductive pattern is electrically connected to the n-type electrode and the p-type electrode by flip chip bonding with the LED chip;
LED package comprising a. The LED package of claim 1, wherein the conductive pattern comprises a transparent metal or metal oxide. The LED package of claim 2, wherein the conductive pattern comprises indium tin oxide (ITO). The LED package of claim 1, wherein the submount includes electrode pads connected to the conductive pattern on a surface opposite to a surface on which the conductive pattern is formed. The LED package of claim 1, wherein the LED device comprises a plurality of LED chips flip-chip bonded to the submount, wherein the plurality of LED chips are connected in series or in parallel by the conductive pattern. The LED package of claim 1, wherein the base mount is a heat radiating substrate made of metal or ceramic. The LED package according to claim 1, further comprising a reflector bonded on the base mount with a cavity surrounding the periphery of the LED element, and a transparent protective member covering the cavity. 8. The LED of claim 7, wherein the LED device includes a plurality of LED chips flip-chip bonded to the submount, and the protection member includes a plurality of lens shapes corresponding to each of the plurality of LED chips. package. The LED package of claim 1, wherein the submount comprises glass or quartz material. As a manufacturing method of the LED package,
(a) preparing a light-transmissive submount having a conductive pattern formed on one surface thereof;
(b) flip chip bonding one or more LED chips on the submount to fabricate an LED device having the submount on the top surface of the LED chip;
(c) bonding the bottom surface of the LED element onto a base mount. The method of claim 10, wherein the step (b) uses a laser as a heat source for the flip chip bonding. an LED chip having an n-type electrode and a p-type electrode; And
The LED chip includes a submount that is flip chip bonded,
The submount is formed of a translucent material for emitting light generated from the LED chip,
The LED device, characterized in that the conductive pattern which is electrically connected to the n-type electrode and the p-type electrode is formed on one surface of the submount.

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