(12) United States Patent
`US 6,707,069 132
`(10) Patent N0.:
`(45) Date of Patent:
`Song et al.
`Mar. 16, 2004
`
`US006707069B2
`
`7/1993 Chen .......................... 362/241
`5,226,723 A *
`3/1994 Ohashi et al.
`........... 428/3084
`5,294,487 A *
`............... 257/81
`3/1994 Okazaki et al.
`5,298,768 A *
`
`7/1996 Chang ................
`257/98
`5,534,718 A *
`9/2000 Isokawa et al.
`..
`257/99
`6,121,637 A *
`
`.....
`8/2001 Oshio et al.
`257/98
`6,274,890 B1 *
`
`8/2002 Lin ...................... 257/99
`6,429,464 B1 *
`
`........... 257/433
`6,483,161 B1 * 11/2002 Kuhara etal.
`.................. 257/100
`6,501,103 B1 * 12/2002 Jory etal.
`6,548,832 B1 *
`4/2003 Sakamoto et a1.
`............ 257/88
`2003/0020399 A1 *
`1/2003 Moller et al.
`............... 313/504
`
`* cited by examiner
`
`Primary Examiner—David Nelms
`Assistant Examiner—Andy Huynh
`(74) Attorney, Agent, or Firm—Lowe Hauptman Gilman &
`Berner LLP
`
`(57)
`
`ABSTRACT
`
`An LED package; made of ceramic substrates and having a
`reflective metal plate; has a first ceramic substrate; Which
`has a chip mounting area on its top surface; and is provided
`With a predetermined conductive pattern formed around the
`chip mounting area. One or more LED chips are seated on
`the chip mounting area of the first ceramic substrate; and are
`connected to the conductive pattern. A second ceramic
`substrate is mounted on the top surface of the first ceramic
`substrate and has a cavity at a position corresponding to the
`chip mounting area. The reflective metal plate is set in the
`cavity of the second ceramic substrate to surround the LED
`chips. The reflective metal plate acts as a heat sink for
`dissipating heat from the LED chips.
`
`6 Claims, 8 Drawing Sheets
`
`120a
`
`(54) LIGHT EMISSION DIODE PACKAGE
`
`(75)
`
`Inventors: Kyung Sub Song; Seoul (KR); Jong
`Pi] Cheon; Kyungki-do (KR)
`
`(73) Assignee: Samsung Electro-Mechanics C0.,
`LTD; Kyungki-do (KR)
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`(21) Appl. No.: 10/173,120
`
`(22)
`
`Filed:
`
`Jun. 18, 2002
`
`(65)
`
`Prior Publication Data
`US 2003/0116769 A1 Jun. 26, 2003
`
`(30)
`
`Foreign Application Priority Data
`
`Dec. 24, 2001
`
`(KR) ........................................ 2001—83876
`
`Int. Cl.7 ................................................ H01L 27/15
`(51)
`(52) US. Cl.
`............................. 257/79; 257/13; 257/98;
`257/99; 257/103; 257/433; 257/434; 257/704
`(58) Field of Search .............................. 257/13.79—103;
`257/433; 434; 675; 676; 704; 706; 918
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`3/1977 Dufft .......................... 313/499
`5/1989 Takahashi et a1.
`350/68
`
`6/1990 Murata ....................... 313/500
`1/1993 Abe ............................ 257/98
`
`****
`
`4,013,915 A
`4,826,271 A
`4,935,665 A
`5,177,593 A
`
`
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`Cree Ex. 1004
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`US. Patent
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`Mar. 16, 2004
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`Sheet 1 0f 8
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`US 6,707,069 B2
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`PRIOR ART
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`FIG. 1a
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`13
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`PR10R ART
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`FIG. 1b
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`Mar. 16, 2004
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`Sheet 2 0f 8
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`US 6,707,069 B2
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`7””””‘
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`“““““
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`PRIOR ART
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`FIG. 2
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`FIG. 3
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`Sheet 4 0f 8
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`155
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`157
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`153
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`170
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`‘55
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`157
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`FIG. 4b
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`FIG. 6
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`___7.-.._. __b_.. .-
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`\ /“"
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`250
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`FIG. 7
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`FIG. 8
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`US 6,707,069 B2
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`1
`LIGHT EMISSION DIODE PACKAGE
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`
`The present invention relates, in general, to light emission
`diode packages with reflective plates of metal and, more
`particularly, to a light emission diode package provided with
`a reflective plate of metal for accomplishing an improved
`heat dissipation effect, in addition to easily controlling its
`luminance and angular distribution of the luminance.
`2. Description of the Prior Art
`As well known to those skilled in the art, light emission
`diode packages (herein below, referred to simply as “LED
`packages”) are semiconductor devices, which have LED
`chips acting as light sources and produced by changing the
`physical and chemical characteristics of some compound
`semiconductor materials, such as GaAs, AlGaAs, GaN,
`InGaN and AlGaInP, and radiate colored lights from the
`LED chips when electrically activated.
`The characteristics of such LED packages are typically
`determined in accordance with colors of emitted lights,
`luminance, and a viewing angle thereof. Such characteristics
`of LED packages are primarily determined by the physical
`and chemical characteristics of compound semiconductor
`materials of LED chips, and secondarily determined by their
`package structures for seating the LED chips therein. In the
`prior art, the improvement in the characteristics of LED
`packages accomplished by the development of compound
`semiconductor materials of LED chips is undesirably lim-
`ited. Therefore, improved structures of LED packages have
`been actively studied in recent years, in addition to study of
`the semiconductor materials of LED chips, in an effort to
`meet the requirement of a high luminous intensity and a
`desired viewing angle (it may also be referred to an angular
`distribution of the luminance). That is, while designing LED
`packages in recent years,
`it
`is desired to consider the
`compound semiconductor materials of LED chips as a
`primary design factor, and the structures of LED packages as
`a secondary design factor.
`Particularly, both the luminance and an angular distribu-
`tion of the luminance of LED packages are mainly affected
`by the secondary design factor, that is, the structures of the
`LED packages.
`For example, a conventional lamp type LED package of
`FIG. 1a and a conventional surface mounted type LED
`package of FIG. 1b are compared with each other in their
`package structures as follows: In the case of the conven-
`tional lamp type LED package 10 of FIG. 1a with two leads
`3a and 3b, the second lead 3b is provided at its top with a
`metal electrode surface, which is depressed to form a
`depression with inclined side surfaces having a predeter-
`mined inclination angle. An LED chip 5 is seated in the
`depression of the metal electrode surface. The two leads 3a
`and 3b with the LED chip 5 are packaged by a hemispherical
`casing 7 of transparent mold resin, thus producing a lamp
`type LED package 10. The conventional surface mounted
`type LED package 20 of FIG. 1b consists of a molded
`package body 11 of epoxy resin, and an LED chip 15
`mounted on the surface of the body 11 at a chip mounting
`area. The LED chip 15 is connected to an electrode (not
`shown) through a plurality of wires 13.
`the
`In the conventional
`lamp type LED package 10,
`hemispherical casing 7 acts as a lens capable of controlling
`the angular distribution of luminance. Particularly, the hemi-
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`spherical casing 7 controls the angular distribution of lumi-
`nance in a way such that the distribution becomes narrow,
`thus increasing the luminous intensity at a predetermined
`angle. In addition, the light radiated from the LED chip 5 is
`reflected by the metal electrode surface of the second lead
`3b, thus increasing the luminous intensity of the LED chip
`5. In comparison with such a lamp type LED package 10, the
`surface mounted type LED package 20 has a wider angular
`distribution of luminance and a lower luminous intensity. It
`is thus noted that the package structures affect the luminance
`and the angular distribution of the luminance of LED
`packages. Therefore,
`in an effort
`to accomplish desired
`characteristics of LED packages, there has been proposed a
`surface mounted type LED package, with an additional light
`reflecting surface formed by coating metal on an inclined
`side surface of the chip mounting area of a molded package
`body and having a predetermined reflective angle.
`Different from such LED packages having molded resin
`bodies,
`it
`is almost
`impossible to desirably control
`the
`luminance or
`the angular distribution of luminance of
`another type LED package, having a ceramic body consist-
`ing of laminated ceramic substrates and widely used in
`recent years. That is, the chip mounting area of such a
`ceramic body must be formed through a punching process,
`a laminating process, and a cutting process, different from
`the molded resin bodies having chip mounting areas formed
`through an resin injection molding process. It is thus very
`difficult to form a side surface of the chip mounting area of
`the ceramic body in such a way that the side surface has a
`desired reflective angle.
`FIG. 2 is a sectional view of a conventional LED package
`having such a ceramic body. As shown in the drawing, the
`ceramic body of the LED package 30 consists of two
`ceramic substrates 21 and 22, each of which is formed by
`laminating a plurality of ceramic sheets. Of the two ceramic
`substrates 21 and 22, the lower substrate 21 is provided at its
`top surface with a chip mounting area for seating an LED
`chip 25 thereon. An electrode 23 extends outward from the
`edge of the chip mounting area to the lower surface of the
`lower ceramic substrate 21 to cover a part of the lower
`surface after passing over the side surfaces of the lower
`ceramic substrate 21. The LED chip 25 is electrically
`connected to the electrode 23 using a plurality of wires 27
`through a wire bonding process. The upper ceramic substrate
`22 is bonded to the top surface of the lower ceramic
`substrate 21, and forms a predetermined cavity surrounding
`the chip mounting area.
`The cavity surrounding the chip mounting area of the
`ceramic body is formed through a punching process or a
`cutting process, so the inside surface of the ceramic body
`defining the cavity is formed as a vertical surface. Therefore,
`different from the LED packages having the molded resin
`bodies, it is difficult to form a coated metal layer on the
`vertical inside surface of the ceramic body. An additional
`inclined surface made of resin may be formed on the vertical
`inside surface of the ceramic body, with a metal layer coated
`on the inclined resin surface in an effort to overcome the
`
`the inclined resin
`above-mentioned problems. However,
`surface may be easily deformed, so it is almost impossible
`to form a desired reflecting surface on the ceramic body.
`In the conventional LED packages having such ceramic
`bodies, it is only possible to control the luminance and the
`angular distribution of the luminance by changing the
`dimension of the chip mounting area and/or the thickness of
`the upper ceramic substrate determining the height of the
`cavity. Therefore, it is difficult to produce LED packages
`having ceramic bodies and meeting the requirement of a
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`US 6,707,069 B2
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`3
`high luminous intensity and a desired angular distribution of
`luminance. However, the ceramic substrates of such LED
`packages have high heat conductivity and a high heat
`dissipation effect, thus effectively solving the problems of
`thermal degradation of LED packages and thermal stress of
`package bodies caused by heat radiated from LED chips.
`Therefore,
`it
`is desired to propose more effective LED
`packages, which use such ceramic substrates having a high
`heat conductivity and a high heat dissipation effect, and
`overcome the structural faults experienced in the conven-
`tional LED packages with ceramic bodies due to the vertical
`inside surface of the ceramic body and leading to difficulty
`in the control of luminance and angular distribution of the
`luminance of the LED packages.
`
`SUMMARY OF THE INVENTION
`
`Accordingly, the present invention has been made keep-
`ing in mind the above problems occurring in the prior art,
`and an object of the present invention is to provide an LED
`package, which has a ceramic body consisting of laminated
`ceramic substrates, with a reflective plate made of a thin
`metal sheet and attached on the vertical inside surface of the
`
`ceramic body defining the cavity of a chip mounting area,
`and which thus accomplishes an improved heat dissipation
`effect thereof, in addition to easily controlling its luminance
`and angular distribution of its luminance.
`the present
`In order to accomplish the above objects,
`invention provides an LED package, comprising: a first
`ceramic substrate having a chip mounting area on a top
`surface thereof, and provided with a predetermined conduc-
`tive pattern formed around the chip mounting area; at least
`one LED chip seated on the chip mounting area of the first
`ceramic substrate, and connected to the conductive pattern;
`a second ceramic substrate mounted on the first ceramic
`
`substrate and having a cavity at a position corresponding to
`the chip mounting area; and a reflective plate made of metal
`and provided in the cavity of the second ceramic substrate so
`as to surround the LED chip.
`In the LED package, the reflective plate preferably has a
`cylindrical structure, with a diameter of the upper end
`thereof being larger than that of the lower end thereof.
`In such a case, the reflective plate can control the angular
`distribution of luminance of the LED chip by changing the
`angle of inclination of the sidewall of the reflective plate,
`with the inclination of the sidewall being formed by a
`difference in the diameter between the upper and lower ends
`of the reflective plate. In addition, the reflective plate can
`control the luminance of the LED chip by changing the
`surface area surrounding the LED chip. Furthermore, the
`reflective plate can control the luminance of the LED chip by
`selecting a reflective plate made of metals with different
`reflectivities. Therefore,
`the present invention provides a
`variety of LED packages, which are produced using ceramic
`substrates and have the luminance and angular distribution
`of the luminance both being controlled as required by users.
`In the LED package of this invention, the reflective plate
`is preferably mounted to the upper surface of the second
`ceramic substrate around the upper edge of the cavity, thus
`effectively dissipating heat to the outside of the LED pack-
`age. In order to allow the reflective plate to effectively
`dissipate heat to the outside of the package, the mounting of
`the reflective plate to the upper surface of the second
`ceramic substrate is preferably accomplished by a silicone-
`based bonding agent having high heat conductivity.
`In order to enhance the heat dissipation effect of the LED
`package, the LED chip is airtightly packaged by a molded
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`insulating part, which is made of a transparent moldable
`material and connected to the reflective plate. In such a case,
`heat dissipated from the LED chip is effectively transferred
`to the reflective plate having such high heat conductivity. In
`the present invention, the transparent moldable material of
`the molded insulating part is selected from epoxy resin or
`silicone-based resin. Of course, it is possible to use another
`resin of high heat conductivity as the transparent moldable
`material of the molded insulating part.
`It is more preferable to extend the upper edge of the
`reflective plate to a predetermined position on the upper
`surface of the second ceramic substrate, in an effort to more
`effectively dissipate heat from the reflective plate.
`In another embodiment of this invention, the LED pack-
`age has a hemispherical lens covering the top of the cavity
`of the second ceramic substrate. In such a case, it is possible
`to control the angular distribution of luminance of the LED
`chip by controlling the distribution of curvature of the lens.
`The hemispherical lens is preferably made of a polymeric
`material.
`
`In the present invention, the first ceramic substrate pref-
`erably consists of a ceramic substrate part having a heat
`dissipating hole formed therethrough, and a ceramic sheet
`covering the heat dissipating hole at the upper surface of the
`ceramic substrate part. In such a case, both the chip mount-
`ing area and the conductive pattern are formed on the upper
`surface of the ceramic sheet. The heat dissipating hole of the
`ceramic substrate part is filled with metal paste.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The above and other objects, features and other advan-
`tages of the present invention will be more clearly under-
`stood from the following detailed description taken in con-
`junction with the accompanying drawings, in which:
`FIGS. 1a and 1b are views schematically showing the
`construction of conventional LED packages;
`FIG. 2 is a sectional view of a conventional LED package
`produced using ceramic substrates;
`FIG. 3 is an exploded perspective view, showing the
`construction of an LED package having a reflective plate in
`accordance with the primary embodiment of the present
`invention;
`FIGS. 4a and 4b are views of an LED package in
`accordance with the second embodiment of the present
`invention;
`FIG. 5 is an exploded perspective view, showing the
`construction of an LED package having a reflective plate in
`accordance with the third embodiment of the present inven-
`tion;
`FIG. 6 is a sectional view of an LED package according
`to the fourth embodiment of the present invention;
`FIG. 7 is a view of an LED package in accordance with
`the fifth embodiment of the present invention; and
`FIG. 8 is a perspective view of an LED package in
`accordance with the sixth embodiment of the present inven-
`tion.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`Reference now should be made to the drawings, in which
`the same reference numerals are used throughout the differ-
`ent drawings to designate the same or similar components.
`FIG. 3 is an exploded perspective view, showing the
`construction of an LED package having a reflective plate in
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`5
`accordance with the primary embodiment of the present
`invention. This drawing shows the LED package, with the
`reflective metal plate 120 separated from the chip mounting
`area of the package body.
`The reflective metal plate 120 is made of a thin metal
`sheet having a high reflectivity, and has a cylindrical shape
`as shown in the drawing. In the cylindrical reflective plate
`120, the diameter “R” of the upper end is preferably larger
`than the diameter “r” of the lower end. In the present
`invention, it is possible to somewhat increase the luminous
`intensity of an LED chip by simply setting a cylindrical
`reflective plate in the chip mounting area without designing
`the reflective plate to have such a difference in the diameter
`between the upper and lower ends. However,
`it is more
`preferable to design the cylindrical reflective plate such that
`the reflective plate has a difference between the diameters
`“R” and “r” of its upper and lower ends and has a desired
`angular distribution of luminance and a desirably increased
`luminous intensity by controlling the diameter difference
`“R—r”.
`
`The reflective plate 120 is preferably manufactured using
`a thin copper sheet
`through an extrusion process or a
`forming process. However, it should be understood that the
`reflective plate 120 may be manufactured using another
`metal sheet in place of the thin copper sheet if the metal
`sheet has desirably high reflectivity and is so thin that the
`sheet is easily formed to a desired cylindrical shape through
`an extrusion process or a forming process.
`During a process of manufacturing the reflective plate
`120, it is preferable to form a support flange 120a along the
`upper edge of the reflective plate 120. In the preferred
`embodiment, one support flange 120a is integrally and
`continuously formed along the circular upper edge of the
`reflective plate 120. However, it should be understood that
`it is possible to form a predetermined number of support
`flanges on desired sections of the upper edge of the reflective
`plate 120 without affecting the functioning of this invention.
`When the reflective metal plate 120 having such a support
`flange 120a is set in the cavity above the chip mounting area
`of the LED package, it is possible to stably rest the reflective
`plate 120 on the upper surface of a ceramic substrate at the
`support flange 120a. Therefore, the reflective plate 120 is
`more stably attached to the LED package. In such a case, a
`silicone-based bonding agent is preferably used for attaching
`the reflective plate 120 to the LED package, in an effort to
`improve the heat dissipation effect of the LED package, as
`will be described in more detail later herein.
`
`As shown in FIG. 3, the reflective metal plate 120 is easily
`set in the cavity above the chip mounting area of the LED
`package. The LED package of this invention is described in
`more detail as follows: The LED package manufactured
`using ceramic substrates according to this invention com-
`prises a first ceramic substrate 101, which has a chip
`mounting area on its top surface for seating an LED chip 105
`thereon. An electrode 103 is formed on the top surface of the
`first ceramic substrate 101, and is connected to the LED chip
`105 through a plurality of wires 107. The electrode 103 is
`formed by a conductive pattern. A second ceramic substrate
`102 is mounted on the first ceramic substrate 101, and has
`a cavity at a position corresponding to the chip mounting
`area. The first and second ceramic substrates 101 and 102
`
`may be preferably made of alumina or SiC. The body of the
`LED package of this invention is made of the ceramic
`substrates 101 and 102 as described above, so the side
`surface of the cavity formed in the second ceramic substrate
`102 to surround the chip mounting area of the first ceramic
`substrate 101 is inevitably formed as a vertical surface in the
`
`6
`same manner as that described for the prior art. In the present
`invention, the vertical side surface of the cavity is covered
`with the reflective metal plate 120. In an operation of this
`LED package, the reflective plate 120 surrounding the LED
`chip reflects light radiated from the LED chip, so the
`luminous intensity of the LED chip is increased. In such a
`case, it is possible to obtain a desired angular distribution of
`luminance of the LED chip by controlling the inclination
`angle of the side surface of the reflective plate 120 during a
`process of manufacturing the plate 120. In an effort
`to
`increase the reflectivity of the reflective plate 120, a coated
`layer, made of Sn, SnPb or Ag, may be formed on the
`reflective plate 120.
`In the present invention, the reflective metal plate may act
`as a heat sink for dissipating heat from the LED chip to the
`outside of the LED package,
`in addition to its original
`function of controlling the luminance of the LED chip and
`the angular distribution of the luminance. The reflective
`metal plate acting as a heat sink is shown in FIGS. 4a and
`4b showing the second embodiment of this invention.
`FIG. 4a shows the cross-sectioned structure of the LED
`
`package according to the second embodiment of this inven-
`tion. In the same manner as that described for the primary
`embodiment of FIG. 3, the LED package of this second
`embodiment comprises two ceramic substrates:
`a first
`ceramic substrate 151 and a second ceramic substrate 152
`
`mounted to the top surface of the first substrate 151. The first
`ceramic substrate 151 has a chip mounting area on its top
`surface for seating an LED chip 155 thereon. A conductive
`pattern is formed on the top surface of the first ceramic
`substrate 151 at a position around the chip mounting area,
`thus forming an electrode 153. The electrode 153 is con-
`nected to the LED chip 155 through a plurality of wires 157,
`thus feeding drive electric power to the chip 155. In this
`embodiment, the conductive pattern of the electrode 153
`preferably extends to the lower surface of the first ceramic
`substrate 151 after passing over the side surfaces of the
`substrate 151 as shown in the drawing. The conductive
`pattern of the electrode 153 is preferably made of an
`Ag/Ni/Au layer.
`The second ceramic substrate 152 has a cavity at a
`position corresponding to the chip mounting area of the first
`ceramic substrate 151. The second ceramic substrate 152 is
`
`mounted on the top surface of the first ceramic substrate 151,
`thus forming a chip mount space for seating the LED chip
`155 therein. In this second embodiment, a heat dissipating
`hole H1 is preferably formed through the first ceramic
`substrate 151 at a position corresponding to the chip mount-
`ing area, thus effectively dissipating heat from the LED chip
`155 to the outside of the LED package. In the LED package
`having such a heat dissipating hole H1 at the first ceramic
`substrate 151, it is necessary to cover the top of the heat
`dissipating hole H1 in an effort to provide a chip mounting
`area. Therefore, the first ceramic substrate 151 of this LED
`package consists of a ceramic substrate part 151a having the
`heat dissipating hole H1 formed therethrough, and a ceramic
`sheet 151b covering the top surface of the ceramic substrate
`part 151a as well as the top of the heat dissipating hole H1.
`The ceramic sheet 151b thus provides a desired chip mount-
`ing area, and covers the top of the heat dissipating hole H1.
`As shown in FIG. 4b which is a plan view of the LED
`package according to the second embodiment of this
`invention, a reflective metal plate 170 is set in the chip
`mount space formed by the cavity of the second ceramic
`substrate 152, and surrounds the LED chip 155 seated on the
`chip mounting area. In the second embodiment, the reflec-
`tive plate 170 has a support flange 170a, at which the
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`US 6,707,069 B2
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`7
`reflective plate 170 is rested on the top surface of the second
`ceramic substrate 152 and which is attached to the area “A”
`
`of the top surface of the substrate 152 using a silicone-based
`bonding agent having high thermal conductivity. The sup-
`port flange 170a formed along the top edge of the reflective
`plate 170 has a substantial width “1”, which allows the
`support flange 170a to more effectively dissipate heat from
`the reflective plate 170 to the outside of the LED package.
`In such a case, heat is primarily transferred from the LED
`chip 155 to the reflective plate, and is secondarily dissipated
`to the surroundings of the LED package through the support
`flange 170a.
`An insulating resin is contained in the chip mount space
`of the LED package according to the second embodiment,
`thus forming an insulating part 159. This insulating part 159
`is connected to the reflective plate 170, and allows more
`effective heat transfer from the LED chip 155 to the reflec-
`tive plate 170. The insulating part 159 is preferably made of
`transparent epoxy resin or silicone-based resin. However, it
`should be understood that the insulating part 159 may be
`formed using another moldable insulating material if the
`material is transparent and has high heat conductivity.
`In the LED package of FIGS. 4a and 4b, the reflective
`metal plate 170 is collaterally used as an effective heat
`dissipating means, which receives heat from the LED chip
`155 through the insulating part 159 and dissipates the heat
`to the surroundings of the package through the support
`flange 170a rested on the top surface of the second ceramic
`substrate 152.
`
`FIG. 5 shows an LED package having a reflective metal
`plate 190 according to the third embodiment of the present
`invention. Different from the circular support flange 170a of
`the reflective metal plate 170 according to the second
`embodiment, the support flange 190a of the reflective metal
`plate 190 of this third embodiment has a rectangular profile
`similar to that of the LED package. The surface area of this
`support flange 190a having such a rectangular profile is
`larger than that of either the support flange 120a of FIG. 3
`or the support flange 170a of FIGS. 4a and 4b, so it more
`effectively dissipates heat to the outside of the package. In
`the present invention, the shape of the support flange of the
`reflective metal plate may be somewhat freely changed in
`accordance with the profile of the LED package and a
`required heat dissipation effect without affecting the func-
`tioning of this invention.
`In addition, the reflective metal plate of this invention
`may be preferably used in LED packages having a variety of
`ceramic substrate structures with vertical inside surfaces
`
`defining the chip mounting spaces of the packages. FIG. 6 is
`a sectional view of an LED package according to the fourth
`embodiment of the present invention.
`In the fourth embodiment of FIG. 6, the LED package has
`a first ceramic substrate, the structure of which is different
`from that of FIGS. 4a and 4b. That is, the second ceramic
`substrate 202 of this LED package has a cavity in the same
`manner as that described for the second embodiment of
`FIGS. 4a and 4b. However, the first ceramic substrate 201 of
`this fourth embodiment consists of lower and upper ceramic
`substrate parts 201a and 201b. The lower ceramic substrate
`part 201a has a heat dissipating hole H2, which is formed
`through the substrate part 201a and has a substantial diam-
`eter. The upper ceramic substrate part 201b has a size
`suitable for being received in the chip mounting space
`formed by the cavity of the second ceramic substrate 202.
`The upper ceramic substrate part 201b acts as a ceramic
`sheet, which covers the top of the heat dissipating hole H2
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`8
`and forms a chip mounting area for seating an LED chip 205
`thereon. In this fourth embodiment, a cylindrical reflective
`metal plate 220 is preferably set in the chip mounting space
`of the package such that the plate 220 is rested on and
`mounted to the top surface of the second ceramic substrate
`202 at its support flange. In the cylindrical reflective plate
`220, the diameter of the top end is larger than that of the
`lower end.
`
`In a brief description, the package structure according to
`this invention is preferably and easily used in any type of
`LED packages if the LED packages have a chip mounting
`space formed by ceramic substrates.
`FIG. 7 is a view of an LED package in accordance with
`the fifth embodiment of this invention. As shown in FIG. 7,
`the general shape of the LED package 250 of this fifth
`embodiment remains the same as that described for the LED
`
`package according to the second embodiment of FIGS. 4a
`and 4b, but the top of the chip mounting space having a
`reflective metal plate 270 is covered with a hemispherical
`lens 280. This hemispherical lens 280 is designed in con-
`sideration of the hemispherical casing used in the conven-
`tional lamp type LED package of FIG. 1a. The hemispheri-
`cal lens 280 is preferably made of a polymeric material. This
`hemispherical lens 280 is preferably used as a means for
`controlling the light emitting angle of an LED chip of the
`package 250 by changing the distribution of curvature of the
`lens 280.
`
`The package structure of this invention may be preferably
`used in another type LED package having a plurality of LED
`chips. FIG. 8 is a perspective view of an LED package
`having both a reflective plate and a plurality of LED chips
`in accordance with the sixth embodiment of this invention.
`
`As shown in FIG. 8, the LED package 310 of the sixth
`embodiment consists of first and second ceramic substrates
`
`301 and 302, and seats four LED chips in its chip mounting
`space formed by the ceramic substrates 301 and 302. The
`four LED chips 305a, 305b, 305C and 305d of this embodi-
`ment are connected to a plurality of electrodes 303 by means
`of a plurality of wires. In the same manner as that described
`for the primary to fifth embodiments, a reflective metal plate
`320 is set in the chip mounting space of the package 310 to
`surround the four LED chips 305a, 305b, 305C and 305d.
`As described above, the present invention provides an
`LED package, which is made of ceramic substrates and has
`a reflective metal plate set in a chip mounting space formed
`by the ceramic substrates. In the LED package of this
`invention, the chip mounting space is formed in the ceramic
`substrates of the package through a punching process, the
`space has a vertical side surface. However, the reflective
`plate made of a thin metal plate is set in the chip mounting
`space, and so it is possible to somewhat freely control the
`luminous intensity of