WO2011136470A2

WO2011136470A2 - Optical package and manufacturing method thereof

Info

Publication number: WO2011136470A2
Application number: PCT/KR2011/001461
Authority: WO
Inventors: Jee Heum Paik
Original assignee: Lg Innotek Co., Ltd.
Priority date: 2010-04-28
Filing date: 2011-03-03
Publication date: 2011-11-03
Also published as: WO2011136470A3; TW201138147A; TWI542031B

Abstract

An optical package and a manufacturing method thereof are provided. The optical package includes an insulating layer including a hole, formed on a circuit pattern layer formed of a conductive material; an optical element bonded onto a portion of the circuit pattern layer, exposed through the hole; a connector electrically connecting the optical element and the circuit pattern layer; and a resin part burying the optical element and the connector. Accordingly, the optical package is formed using a tape board to reduce the volume and thickness of the optical package. Furthermore, a surface emission type package instead of a conventional dot emission type package can be manufactured to produce a highly integrated package. Moreover, encapsulation and formation of a lens are simultaneously performed to reduce the manufacturing cost and simplify the manufacturing process to improve productivity and increase optical efficiency through a light reflecting layer formed through plating.

Description

OPTICAL PACKAGE AND MANUFACTURING METHOD THEREOF

The present invention relates to an optical package and a manufacturing method thereof and, more particularly, to an optical package and a manufacturing method thereof to reduce the volume and thickness of the optical package and improve the integration and optical efficiency of the optical package.

A light emitting diode (LED) is an intermetallic compound junction diode which generates minority carriers (electrons or holes) using p-n junction of semiconductor and converts electric energy into light energy according to recombination of electrons and holes to thereby emit light. More specifically, when a forward voltage is applied to a specific semiconductor element, electrons and holes move through the junction of positive and negative electrodes and are recombined. Here, recombined electrons and holes have energy smaller than the energy of electrons and holes before being recombined, and thus light is emitted due to the energy difference. The LED has wide application including general display devices, lighting devices and LCD backlight units, etc. Particularly, the LED has advantages of low heat and a long life due to a low driving voltage and high energy efficiency. The LED is expected to replace currently used most light source devices with the development of techniques capable of providing white light with high luminance.

FIG. 1 is a cross-sectional view of a conventional LED package. Referring to FIG. 1, the LED package is constructed in such a manner that a gold wire 102 is connected to a light-emitting GaN compound chip 60 through bonding and a heat sink 10 is formed under the GaN compound chip to radiate heat. In addition, a metal lead 20 is connected to an external support and the LED package through wire bonding and electricity is applied through the metal lead 20 to emit light. The individual chip 60 having this structure is mounted in s a single package.

The conventional LED package has a lead type package form.

However, the lead frame type package is difficult to integrate LED chips due to a small package available area. Furthermore, the package size against the chip size is relatively large, and thus the thickness or external area of a product having the lead frame type package mounted therein is increased. Moreover, the heat sink is required to radiate heat generated from the LED chip to result in increases in the thickness and volume of the LED package.

FIG. 2 illustrates another conventional LED package. Referring to FIG. 2, after phosphor and resin composite is coated through an encapsulation process for protecting the wire 102, a plastic lens 25 is used to improve straightness of light and optical efficiency. This causes a limitation in reducing the size of the LED package and increases manufacturing cost.

Accordingly, a technique capable of manufacturing a small-size LED package through a simplified process at a low cost is required.

The present invention provides an optical package and a manufacturing method thereof to reduce the volume and thickness of the optical package at a low cost so as to achieve a small-sized highly integrated LED chip and plate a metal layer functioning as a heat sink and a support with a light-reflecting material to improve optical efficiency.

According to an aspect of the present invention, there is provided an optical package comprising an insulating layer including a hole, formed on a circuit pattern layer formed of a conductive material; an optical element bonded onto a portion of the circuit pattern layer, exposed through the hole; a connector electrically connecting the optical element and the circuit pattern layer; and a resin part burying the optical element and the connector.

The portion of the circuit pattern layer, exposed through the hole, may have a light reflecting layer formed thereon. In this case, the light reflecting layer may be also formed on the backside of the circuit pattern layer on which the insulating layer is formed and the light reflecting layer may include Ag.

The optical package may further comprise a solder resist layer that is formed on the insulating layer and forms a barrier around the optical element and the connector, and the resin part may be formed inside the barrier composed of the solder resist layer and bury the optical element and the connector.

The conductive material may be Cu.

The outer surface of the circuit pattern layer and the connector may be formed of one of Au, Al and Cu.

The insulating layer may be a polyimide film.

The resin part may be formed of phosphor and transparent resin and the transparent resin may be silicon.

The resin part may have a flat surface or a convex lens shape.

The resin part may bury at least part of the insulating layer.

According to another aspect of the present invention, there is provided a method of manufacturing an optical package, which comprises a step (a) of forming a hole in an insulating layer; a step (b) of forming a circuit pattern layer of a conductive material under the insulating layer; a step (c) of bonding an optical element onto a portion of the circuit pattern layer, exposed through the hole; a step (d) of electrically connecting the optical element to an exposed portion of the circuit pattern layer, which is separated from the portion of the circuit pattern layer onto which the optical element is bonded through a connector; and a step (e) of forming a resin part burying the optical element and the connector.

The step (c) forms a light reflecting layer on the portion of the circuit pattern layer, exposed through the hole, through plating and bonds the optical element onto the circuit pattern layer. In this case, the step (c) forms the light reflecting layer on the backside of the circuit pattern layer on which the insulating layer is formed through plating.

The manufacturing method may further comprise the step of forming a solder resist layer on the insulating layer to construct a barrier around the portion of the circuit pattern layer, exposed through the hole, between the steps (b) and (c), The step (e) forms the resin part inside the barrier composed of the solder resist layer to bury the optical element and the connector.

The step (b) may comprise the step of plating the outer surface of the circuit pattern layer with gold and the connector may be formed of gold.

The resin part may include phosphor and transparent resin. In this case, the step (e) may form the resin part having a flat surface or over-coat the phosphor and transparent resin to form a resin part in the form of a convex lens.

According to the present invention, an optical package is formed using a tape board to reduce the volume and thickness of the optical package. Furthermore, a surface emission type package instead of a conventional dot emission type package can be manufactured to produce a highly integrated package. Moreover, encapsulation and formation of a lens are simultaneously performed to reduce the manufacturing cost and simplify the manufacturing process to improve productivity and increase optical efficiency through a light reflecting layer formed through plating.

The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:

FIG. 1 is a cross-sectional view of a conventional optical package;

FIG. 2 illustrates another conventional optical package;

FIG. 3 is a cross-sectional view showing a process of manufacturing an optical package according to a first embodiment of the present invention;

FIG. 4 is a cross-sectional view for comparing the optical package according to the first embodiment of the present invention to the conventional optical package shown in FIG. 1;

FIG. 5 is a plan view showing a polyimide film and a circuit pattern layer of the optical package according to the first embodiment of the present invention;

FIG. 6 is a view for explaining the degree of integration of the optical package according to the first embodiment of the present invention;

FIG. 7 is a cross-sectional view showing a process of manufacturing an optical package according to a second embodiment of the present invention;

FIG. 8 is a cross-sectional view for comparing the optical package according to the second embodiment of the present invention to the conventional optical package shown in FIG. 1;

FIG. 9 is a plan view showing a polyimide film and a circuit pattern layer of the optical package according to the second embodiment of the present invention;

FIG. 10 is a view for explaining the degree of integration of the optical package according to the second embodiment of the present invention;

FIG. 11 is a cross-sectional view showing a process of manufacturing an optical package according to a third embodiment of the present invention;

FIG. 12 is a cross-sectional view for comparing the optical package according to the third embodiment of the present invention to the conventional optical package shown in FIG. 1;

FIG. 13 is a plan view showing a polyimide film and a circuit pattern layer of the optical package according to the third embodiment of the present invention; and

FIG. 14 is a view for explaining the degree of integration of the optical package according to the third embodiment of the present invention.

The present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art.

FIG. 3 is a cross-sectional view showing a process of manufacturing an optical package according to a first embodiment of the present invention.

Referring to FIG. 3,

holes

105 and 106 are formed in an insulating film, for example, a polyimide film 103, through punching in step S2. The holes include a device hole 105 corresponding to a central hole in which an optical element will be located and a via-hole 106 through which a connector (for example, a wire) passes to supply power to the optical element. Copper foil is laminated on the polyimide film 103 having the

holes

105 and 106 in step S3. Then, the exposed surface is activated through chemical treatment, and photoresist is coated on the surface, exposed and developed. After the developing process, a required circuit is formed through etching and the photoresist is stripped off to form a circuit pattern layer 104 in step S4.

Subsequently, gold plating is performed on the circuit pattern layer 104 and the

holes

105 and 106 to process the surfaces of the circuit pattern layer 104 and the

holes

105 and 106 to be bondable, and solder resist 101 is coated on portions of the surface of the polyimide layer 103 other than a portion for bonding and holes for supplying external power in step S5. Specifically, the solder resist 101 is coated to form a barrier that surround a die pad portion of the circuit pattern layer 104, onto which the optical element will be bonded, and portions of the circuit pattern layer 104, which are connected to the optical element through wire bonding. The solder resist barrier 101 formed in this manner can protect the circuit pattern layer 104 and form a solder resist dam to allow phosphor to be laterally coated inside the solder resist dam.

The optical element 60 is bonded onto a portion of the copper foil surface on the polyimide film 103, on which the optical element 60 will be located, that is, the die pad portion, through die bonding in step S6. Then, a wire 102 formed of gold is electrically connected to a portion of the circuit pattern layer 104, which is isolated from the die pad portion through the via-hole 106, to provide power to the optical element 60 in step S7. A resin part 100a is formed inside the solder resist barrier 101 to bury the optical element 60 and the wire 102 in step S8. Specifically, phosphor and transparent resin composed for white LED are coated inside the solder resist barrier 101 to form the resin part 100a with a flat surface to thereby accomplish the optical package.

FIG. 4 is a cross-sectional view for comparing the optical package according to the first embodiment of the present invention to the conventional optical package shown in FIG. 1. Referring to FIG. 4, the present invention can achieve the small-size integrated optical package through the film type insulating layer 103 and the circuit pattern layer 104 formed under the insulating layer 103 without using the heat sink 10 and the metal lead 20 of the conventional optical package.

FIG. 5 is a plan view showing the polyimide film and the circuit pattern layer of the optical package according to the first embodiment of the present invention. Referring to FIG. 5, the optical package of the present invention has a degree of integration much higher than that of the conventional optical package (shown in the right part of FIG. 4).

FIG. 6 is a view for showing the degree of integration of the optical package according to the first embodiment of the present invention. Referring to FIG. 6, a very large number of optical packages according to the present invention can be arranged in an area having a predetermined size, as shown in the right part of the FIG. 6, as compared to the conventional optical packages having the metal lead and the heat sink, arranged in an area having the same size, as shown in the left part of the FIG. 6.

FIG. 7 is a cross-sectional view showing a process of manufacturing an optical package according to a second embodiment of the present invention. Referring to FIG. 7, the

holes

105 and 106 are formed in an insulating film, for example, the polyimide film 103, through punching in step S1. The holes include a device hole 105 corresponding to a central hole in which an optical element will be located and a via-hole 106 through which a wire passes to supply power to the optical element. Copper foil is laminated on the polyimide film 103 having the

holes

105 and 106 in step S2. Then, the exposed surface is activated through chemical treatment, and photoresist is coated on the surface, exposed and developed. After the developing process, a required circuit is formed through etching and the photoresist is stripped off to form the circuit pattern layer 104 in step S3.

holes

105 and 106 to process the surfaces of the circuit pattern layer 104 and the

holes

105 and 106 to be bondable, and the solder resist 101 is coated on portions of the surface of the polyimide film 103 other than a portion for bonding and holes for supplying external power in step S4. More specifically, the solder resist 101 is coated to form a barrier that surrounds a die pad portion of the circuit pattern layer 104, onto which the optical element will be bonded, and portions of the circuit pattern layer 104, which are connected to the optical element through wire bonding.

The optical element 60 is bonded onto a predetermined portion of the copper foil laminated on the polyimide film 103, on which the optical element 60 will be located, that is, the die pad portion, through die bonding in step S5. Then, the wire 102 formed of gold is electrically connected to a portion of the circuit pattern layer 104, which is insulated from the die pad portion through the via-hole 106 to as to provide power to the optical element 60 in step S6. A resin part 100b is formed inside the solder resist barrier 101 to bury the optical element 60 and the wire 102 in step S7. Specifically, phosphor and transparent resin composed for white LED are over-coated inside the solder resist barrier 101 to form the resin part 100b in a convex lens form to thereby accomplish the optical package. When the phosphor and transparent resin are over-coated, the convex lens shaped resin part 100b is formed due to surface tension, as shown in FIG. 7. Accordingly, the resin part and a plastic lens can be simultaneously formed.

FIG. 8 is a cross-sectional view for comparing the optical package according to the second embodiment of the present invention to the conventional optical package shown in FIG. 1. Referring to FIG. 8, the present invention can achieve the small-size integrated optical package through the film type insulating layer 103 and the circuit pattern layer 104 formed under the insulating layer 103 without using the heat sink 10 and the metal lead 20 of the conventional optical package. Furthermore, the optical package of the present invention includes the resin part 101b having both a resin function and a plastic lens function to improve straightness of light and optical efficiency.

FIG. 9 is a plan view showing the polyimide film and the circuit pattern layer of the optical package according to the second embodiment of the present invention. Referring to FIG. 9, the optical package of the present invention has a degree of integration much higher than that of the conventional optical package (shown in the right part of FIG. 9).

FIG. 10 is a view for showing the degree of integration of the optical package according to the second embodiment of the present invention. Referring to FIG. 10, a very large number of optical packages according to the present invention, which have the resin part and the plastic lens, can be arranged in an area having a predetermined size, as shown in the right part of the FIG. 10, as compared to the conventional optical packages having the metal lead and the heat sink, arranged in an area having the same size, as shown in the left part of the FIG. 10.

FIG. 11 is a cross-sectional view showing a process of manufacturing an optical package according to a third embodiment of the present invention. Referring to FIG. 11, the

holes

105 and 106 are formed in an insulating film, for example, the polyimide film 103, through punching in step S2. The holes include a device hole 105 corresponding to a central hole in which an optical element will be located and a via-hole 106 through which the wire 102 as a connector passes to supply power to the optical element 60. Then, a metal layer 104 is laminated on the polyimide film 103 having the

holes

105 and 106 in step S3. Here, the metal layer 103 may be copper.

Subsequently, the exposed surface is activated through chemical treatment, and photoresist is coated on the surface, exposed and developed. After the developing process, a required circuit is formed through etching and the photoresist is stripped off to form the circuit pattern layer 104. Solder resist is coated on the insulating film 103, that is, on portions of the surface of the circuit pattern layer 104 other than the portion corresponding to the hole 105 for bonding and the via-hole 106 for supplying external power and printed to form the solder resist layer 101 in step S4.

The surface of the circuit pattern layer 104, exposed through the

holes

105 and 106, is plated to form a light reflecting layer 107 such that the surface of the circuit pattern layer 104 is processed to be bondable in step S5. In this case, the light reflecting layer 107 may be formed on the backside of the circuit pattern layer 104. In addition, the surface of the circuit pattern layer 104 may be plated with Ag to form the light reflecting layer 107. When silver plating instead of gold plating is performed on the circuit pattern layer 104, it is possible to reduce absorption of light in the polyimide film 103 and improve light efficiency.

Subsequently, the optical element 60 is mounted on the portion of the light reflecting layer 107, which corresponds to the hole 105, through die bonding in step S6. The optical element 60 may be an LED chip and may be mounted using an adhesive. Then, the wire 102 formed of gold is bonded onto the light reflecting layer 107 to electrically connect the circuit pattern layer 104 and the LED chip 60 in step S7. A resin part 100 is formed to bury the LED chip 60 and the wire 102 in step S8. Specifically, phosphor and transparent resin composed for white LED are over-coated inside the solder resist pattern 101 to form the resin part 100 in a convex lens form. Accordingly, encapsulation and formation of a plastic lens can be simultaneously performed.

FIG. 12 is a cross-sectional view for comparing the optical package according to the third embodiment of the present invention to the conventional optical package shown in FIG. 1. Referring to FIG. 12, the insulating film 103 including the holes is formed on the metal layer 104 corresponding to the circuit pattern layer and the light reflecting layer 107 is formed on the surface of the metal layer 104, exposed through the holes, through plating. Here, it is desirable that the solder resist layer 101 is formed on the insulating film 103, the insulating film 103 is a polyimide film and the metal layer 104 is formed of copper. In addition, it is desirable that the light reflecting layer 107 is also formed on the backside of the metal layer 104 having the insulating film 103 formed on the front surface thereof and the light reflecting layer 107 is plated with Ag. That is, the light reflecting layer 107 is formed through silver plating instead of gold plating to increase luminance and thermal conductivity so as to improve radiation of heat generated from the LED chip 60 and increase reflectivity so as to prevent light absorption and maximize optical efficiency.

Furthermore, the optical package in the present embodiment of the invention is in the form of a tape type LED package in which the LED chip is mounted on the light reflecting layer 107 as the optical element 60 and electrically connected to the circuit pattern layer 104 through the wire 102 and the LED chip 60 and the wire 102 are buried with the resin part 100. Here, the resin part 100 is in the form of a convex lens and includes phosphor or transparent resin. The transparent resin may be silicon.

As described above, the present invention can achieve the small-size integrated optical package through the insulating film 103 and the circuit pattern layer 104 formed under the insulating layer 103 without using a heat sink and a metal lead. Furthermore, the circuit pattern layer 104 formed under the insulating film 103 functions as a heat sink as well as a circuit board. Moreover, the bonding force of wire bonding can be improved due to RZ difference according to surface roughness.

FIG. 13 is a plan view showing the polyimide film and the circuit pattern layer of the optical package according to the third embodiment of the present invention. Referring to FIG. 13, the optical package of the present invention has a degree of integration much higher than that of the conventional optical package (shown in the right portion of FIG. 13).

FIG. 14 is a view for showing the degree of integration of the optical package according to the third embodiment of the present invention. Referring to FIG. 14, a very large number of optical packages according to the present invention can be arranged in an area having a predetermined size, as shown in the right part of the FIG. 6, as compared to the conventional optical packages having the metal lead and the heat sink, arranged in an area having the same size, as shown in the left part of the FIG. 14.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.

Claims

An optical package comprising:

an insulating layer including a hole, formed on a circuit pattern layer formed of a conductive material;

an optical element bonded onto a portion of the circuit pattern layer, exposed through the hole;

a connector electrically connecting the optical element and the circuit pattern layer; and

a resin part burying the optical element and the connector.
The optical package of claim 1, wherein the portion of the circuit pattern layer, exposed through the hole, has a light reflecting layer formed thereon.
The optical package of claim 2, wherein the light reflecting layer is formed on the backside of the circuit pattern layer on which the insulating layer is formed.
The optical package of claim 3, wherein the light reflecting layer includes Ag.
The optical package of claim 1 or 2, further comprising a solder resist layer that is formed on the insulating layer and forms a barrier around the optical element and the connector,

wherein the resin part is formed inside the barrier composed of the solder resist layer and buries the optical element and the connector.
The optical package of claim 1 or 2, wherein the conductive material is Cu.
The optical package of claim 1, wherein the outer surface of the circuit pattern layer and the connector are formed of one of Au, Al and Cu.
The optical package of claim 1 or 2, wherein the insulating layer is a polyimide film.
The optical package of claim 1 or 2, wherein the resin part is formed of phosphor and transparent resin.
The optical package of claim 9, wherein the transparent resin is silicon.
The optical package of claim 1 or 2, wherein the resin part has a flat surface or a convex lens shape.
The optical package of claim 1, wherein the resin part buries at least part of the insulating layer.
A method of manufacturing an optical package, comprising:

a step (a) of forming a hole in an insulating layer;

a step (b) of forming a circuit pattern layer of a conductive material under the insulating layer;

a step (c) of bonding an optical element onto a portion of the circuit pattern layer, exposed through the hole;

a step (d) of electrically connecting the optical element to an exposed portion of the circuit pattern layer, which is separated from the portion of the circuit pattern layer onto which the optical element is bonded through a connector; and

a step (e) of forming a resin part burying the optical element and the connector.
The method of claim 13, wherein the step (c) forms a light reflecting layer on the portion of the circuit pattern layer, exposed through the hole, through plating and bonds the optical element onto the circuit pattern layer.
The method of claim 14, wherein the step (c) forms the light reflecting layer on the backside of the circuit pattern layer on which the insulating layer is formed through plating.
The method of claim 13 or 14, further comprising the step of forming a solder resist layer on the insulating layer to construct a barrier around the portion of the circuit pattern layer, exposed through the hole, between the steps (b) and (c),

wherein the step (e) forms the resin part inside the barrier composed of the solder resist layer to bury the optical element and the connector.
The method of claim 13, wherein the step (b) comprises the step of plating the outer surface of the circuit pattern layer with gold.
The method of claim 16, wherein the resin part includes phosphor and transparent resin.
The method of claim 18, wherein the step (e) forms the resin part having a flat surface or over-coats the phosphor and transparent resin to form a resin part in the form of a convex lens.