c12) United States Patent
`Hsu
`
`I 1111111111111111 11111 111111111111111 IIIII 111111111111111 IIIIII IIII IIII IIII
`US006770498B2
`US 6,770,498 B2
`Aug. 3, 2004
`
`(10) Patent No.:
`(45) Date of Patent:
`
`(54) LED PACKAGE AND THE PROCESS
`MAKING THE SAME
`
`(75)
`
`Inventor: Cheng-Hsiang Hsu, Taichung (1W)
`
`(73) As.signees: Lingsen Precision industries, Ltd.,
`Taichung (TW); Cotco Holdings Ltd.,
`Kwai Chung (HK)
`
`( *) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 56 days.
`
`(21)
`
`(22)
`
`(65)
`
`(30)
`
`Appl. No.: 10/263,805
`Oct. 4, 2002
`
`filed:
`
`Prior Publication Data
`
`US 2004/0000727 Al Jan. J, 2004
`Foreign Application Priority Data
`
`Jun. 26, 2002
`lot. Cl.7
`
`(51)
`
`(TW) ....................................... 91113988 A
`
`.......................... ...... .. . ... ... ....... H0lL 21/66
`
`(52) U.S. Cl . ............................................ 438/26; 438/29
`
`(58) F ield of Search .............................. 438/26, 27, 28,
`438/29, 34; 257/98, 99, 100, 79, 81, 787
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`5,698,866 A * 12/1997 Doiron et al. .. .............. 257/99
`lsokawa el al. ............... 257/99
`6,670,648 B2 • 12/2003
`6,707,069 B2 * 3/2004 Song el al. ................... 257/79
`* cited by examiner
`Primary Examiner-Sara Crane
`(74) Attorney, Agent, or Firm-Erowdy and Neimark
`ABSTRACT
`(57)
`
`The present invention is to provide a process for fabricating
`light emilling diode (LED) packages. The process begins
`with a first step of providing a platelike frame bavi(cid:143) g a
`plurality of cells, each of which is composed of a mai(cid:143) plaie
`and a separate arm. Secondly, an LED die and a reflecting
`ring are respectively mounted on a top surface of each main
`plate sucb that the die is located at a center of the reflecting
`ring. Next, connect a conductive wire between a top surface
`of the die and a top surface of the separate arm by wire
`bonding technique. And then, mold a domed transparent
`eocapsulant on each of the cells. The encapsulant encapsu(cid:173)
`lates tbe die, the reflecting ring and the conductive wire and
`covers tbe main plate and the separate arm, and fills a space
`between the main plate and the separate arm to remain their
`spaced apart. Finally, cut the frame according to the size of
`each cell, and then LED packages are obtained.
`
`5 Claims, 8 Drawing Sheets
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`U.S. Patent
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`Aug. 3, 2004
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`Sheet 1 of 8
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`US 6,770,498 B2
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`providing a platelike frame
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`' .
`
`attaching LED dies on the frame
`
`, r
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`molding reflecting rings on the frame
`
`' .
`connecting the dies to the frame by
`bonding wires
`
`,r
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`molding encapsulants on the frame
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`, .
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`cutting the frame to packages
`
`FIG. 1
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`U.S. Patent
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`US 6,770,498 B2
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`U.S. Patent
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`Aug. 3, 2004
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`Sheet 3 of 8
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`US 6,770,498 B2
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`1 0 -~~
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`FIG. 3
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`16
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`20
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`FI G.5
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`16
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`31
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`20
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`30
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`FIG.7
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`FIG. 9
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`10
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`10
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`10
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`U.S. Patent
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`Aug. 3, 2004
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`Sheet 4 of 8
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`US 6,770,498 B2
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`C>
`('-1
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`U.S. Patent
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`U.S. Patent
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`Aug. 3, 2004
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`Sheet 8 of 8
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`US 6,770,498 B2
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`31
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`20
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`so
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`51
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`FIG . 11
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`'-- 70
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`FIG. 12
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`US 6,770,498 B2
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`1
`LEO PACKAGE AND THE PROCESS
`MAKING THE SAME
`
`FIELD OF T HE INVENTION
`
`The present invention relates generally to photoelectric
`semiconductor, and more particularly to a process for fab(cid:173)
`ricating a bght emilting diode (LED) package and the
`strncture of the LED package.
`
`BACKGROUND OF THE INVENTION
`
`2
`sloping inner surface, and the die is positioned in the center
`of the reflecting ring. Step C: Connect the other electrode on
`a top surface of the die to a top surface of the separate arm
`with a conductive wire by means of wire bonding technique.
`5 Step D: Form an encapsulant on each cell of the frame with
`epoxy resin by means of the molding technique, wherein the
`eocapsulant encapsulates the die, the reflecting ring and the
`conductive wire, and covers the main plate and the separate
`am1 and also fills the space between the main plate and the
`10 separate arm Lo remain their spaced apart in opposite rela(cid:173)
`tionship. Additionally, the encapsulant has a top domelike
`protrusion. Step E: Cut the platelike frame substantially
`according to the size of each of the cells such that a plurality
`of LED packages are made.
`
`A conventional lamp-typed LED package is made by the
`following process. Firstly, provide a frame made of an
`electrically conductive metal. The frame has a numbers of 15
`pairs of leads arranged parallel and interconnected with each
`others through a cross bar. Each pair of leads is served as a
`positive pole and a negative pole of one LED package. On
`one of the poles, generally the negative pole, a bowl-shaped
`recess defining a reflecting surface for reflecting light is 20
`formed. Next, an LED die is attached on a bottom of the
`bawl-shaped recess of each negative pole by an electrically
`conductive adhesive, e.g. silver adhesive, such that an
`N-electrode of the LED die is electrically connected to the
`negative pole. Then, a P-electrode o[ each LED die is 25
`electrically connected to the other lead, i.e. the positive pole,
`through a gold wire by wire-bonding technique. By means
`of a molding technique, the LED dies are then respectively
`encased by a dome-shaped epoxy resin eocapsulaol with the
`metallic leads partially projecting out of the respective 30
`encapsu lant and the cross bar is exposed outside the encap(cid:173)
`sulants. Finally, the cross bar is cut to obtain a numbers of
`LED packages.
`Compared with other lighting devices, such as fluorescent
`lamps and incandescent lamps, the heat emitted by the LED
`package is low, but a certain amount of the heat, which is
`generated while the LED die glows by the electricity of from
`tens to hundreds of milliamperes, is a major factor resulted
`in the damage of the LED package. Accordingly, the present
`research and improvement is also focused on reducing the 40
`beat generated by the LED die. As far as the foregoing prior
`art LED package is concerned, the die is encapsulated in the
`epoxy encapsulant, which them,al conductivity is poor, and
`the contact area between the die and one of the leads is
`small. Besides, a protrudent portion of the leads out of the 45
`encapsulant is in the shape of a thin bar, so that the thermal
`conductivity of the above-mentioned conventional LED
`package is very poor and further improvement is required.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FlG. 1 is a flow chart showing a process for fabricating
`LED packages of a preferred embodinlent in accordance
`with the present invention;
`FIG. 2 shows semi-finished LED packages of the first step
`according to FIG. 1;
`FIG. 3 is a cross-sectional view taken along the direction
`indicated by the line 3-3 as shown in FIG. 2;
`FIG. 4 shows semi-finished LED packages of the second
`step according to FIG. 1;
`FIG. S is a cross-sectional view taken along the direction
`indicated by the line 5-5 as shown in FIG. 4;
`FIG. 6 shows semi-finished LED packages of the third
`step according to FIG. 1;
`FIG. 7 is a cross-sectional view taken along the direction
`indicated by the line 7- 7 as shown in FlG. 6;
`FIG. 8 shows semi-finished LED packages of the fourth
`35 step according to FIG. 1;
`FIG. 9 is a cross-sectional view take n along the direction
`indicated by the line 9-9 as shown in FIG. 8;
`Fl G. 10 shows semi-finished LED packages o[ the fifth
`step according to FIG. l ;
`FIG. 11 is a cross-sectional view taken along the direction
`indicated by the line 11- 11 as shown in FIG. 10; and
`FIG. 12 shows a finished LED package of the preferred
`embodiment of the present invention.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`The preferred embodiment o( the present invention is to
`provide a process for fabricating white LED packages.
`50 However, it is to be understood that this process can be
`applied to make any kind of the LED lamp packages.
`Reforring to FIG. 1, a flow chart of a fabricative process of
`the present invention includes six steps of plate-like frame
`providing, die bonding, reflecting ring molding, wire
`55 bonding, encapsulant molding, and culling. The details of
`the steps will be illustrated hereunder with the accompany(cid:173)
`ing drawings.
`Step l: Referring 10 FIGS. 2- 3, firstly, provide a plate-like
`frame 10, which is substantially rectangle and bas a plurality
`60 of cells 11. The cells 11, each of which bas a plurality of
`openings, are well positioned in an arraogement of matrix.
`Namely, the cells 11 are surrounded by left and right lateral
`sides, which are defined as two longitudinal lateral bars 12,
`and upper and lower sides, which are defined as two
`65 transversal lateral bars 13, wherein each of the cells 11 is
`comparted by a plurality of longitudinal dividing bars 14 and
`transversal dividing bars 15. The openings of the cell 11 are
`
`SUMMARY OF THE INVENTION
`
`The primary objective of the present invention is to
`provide a process for fabricating LED packages, whereby a
`better thermally conductive and durable LED packages are
`made.
`To achieve the foregoing objective of the present
`invention, the process for fabricating LED packages
`involves the following steps. Step A: Provide a platelike
`frame made of an electrically conductive metal. The frame
`bas a plurality of cells, each of which includes a main plate
`and a separate arm, and no connection but a space between
`the main plate and the separate arm. Step B: Attach an LED
`die on a top surface of each main plate of the frame so as to
`electrically connect an electrode on a bollom side of the die
`to the main plate. Moreover, form a reflecting ring on each
`main plate with a molding technique, wherein the re flecting
`ring is made of opaque white plastic and bas an upward
`
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`US 6,770,498 B2
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`10
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`15
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`20
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`30
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`3
`alike in shape, that is, the cell 11 has a rectangle main plate
`16 at a center thereof, and two bridges 17 respectively at two
`centers of the upper and the lower lateral sides to connect the
`maio plate 16 aod the transversal dividing bar 15 or the
`transversal lateral bars 13, and ao extending arm 18 at tl1e 5
`middle of right lateral side of the cell 11 to connect the main
`plate 16 and the longitudinal dividing bars 14 or the longi(cid:173)
`tudinal lateral bars 12, and an separate arm 19 al the middle
`of left lateral side of the cell 11 to connect only the
`longitudinal dividing bar 14 or the longitudinal lateral bar 12
`but to be spaced apart from the main plate 16.
`Step 2: Referring to FIGS. 4--5, a white LED die 20 is
`bonded on a top surface of each of the main plates 16 of the
`frame 10 by means of silver adhesives (not shown). 'l11e die
`20 bas a bottom to be smoothly bonded on the top surface
`of the main plate 16 such that an electrode positioned on the
`bottom of the die 20 directly electrically contacts the main
`plate 16 by means of the s ilver adhesive. Please note that the
`LED die 20 is a prior art, wbicb epitaxy structure and how
`to glow are irrelevant to the present invention, will not
`recited thereafter. lo addition, tbe technique of die bonding
`is also a prior art.
`Step 3: Referring to FIGS. 6-7, form a reflecting ring 30,
`which is bonded oo each of tbe main plates 16 of tlie frame
`10, with plastic materials by means of injection molding 25
`technique. The reflecting ring 30, which axial beigbt is
`almost the same with the die's 20 and which is made of
`opaque white material, surrounds the die 20 and has an inner
`surface 31, wbicb is a slope facing upward with an angle of
`45° to reflect tbe light emitted by the die 20. Further, to
`facilitate the molding operation, tbe neighboring reflecting
`rings 30 in the same row are connected with a connecting bar
`32, which is mounted oo the bridges 17 of the frame LO. The
`applicant would like to clarify that tbe step 3 can be prior to
`step 2, i.e., form the reflecting ring 30 on tbe frame 10 first,
`and then bond the die 20 on the main plate.
`Step 4: Referring to FJGS . 8-9, connect a top surface of
`the die 20 to a top surface of the separate arm 19 of the cell
`11 with a gold conductive wire 40 of 99% Au by wire
`bonding technique such that tbe other electrode positfoned
`oo tbe top surface of the die 20 can be electrically connected
`with Lbe separate am, 19.
`Step 5: Referring to FIGS. 10-11, form an encapsulant 50
`on each of tbe cells 11 of tbe frame 10 with epoxy resin by
`means of tbe injection molding technique. Tbe encapsulant
`50 bas a rectangle base 51, which corresponds to the cell 11
`in size and fills tbe opening$ o[ the cell 11 and covers the
`surface of the frame 10 with a predetermined thickness. All
`tbe bases 51 of tbe encapsuJants 50 arc integrated together
`initially, so that tbe encapsulants 50 not only cover tbe main 50
`plates 16, the bridges 17, the exteodiog arms 18 and the
`separate arms 19 of tbe cells 11 but also tbe dividing bars 14
`and 15 of the frame 10. In this embodiment of the present
`invention, tbc base 51 is higher than the frame 10 and
`substantially as high as tbe reflecting ring 30. The encapsu- 55
`!ant 50 bas a top domelike protrusion 52, which is located oo
`the top of the base 51 and integrated with the base 51, and
`not only encapsulates the die 20, tbe reflecting ring 30, and
`the conductive wire 40 on the cell 11 to maintain the
`mechanism of the die 20 and to prevent water from 60
`inftltration, but also reflects the light emitted by tbe die 20
`through the inner surface 31 of the reflecting ring 30. la
`addit.ion, tbe eacapsulaat 50 is an insulator.
`Step 6: Cut the frame 10 according to tbe size of each of
`the cell 11, or smaller, by cutting out the lateral bars 12 and 65
`13 and the dividing bars 14 aod 15 of tlie frame 10 such that
`LEO packages 60 are made.
`
`4
`Referring to FIGS. 11- 12, the LEO 60 package made by
`the foregoing fabricative process structurally includes a first
`terminal 70, a second terminal 80, tbe LED die 20, the
`reflecting ring 30, the conductive wire 40, aod the encap(cid:173)
`s ulaat 50. Tbe first terminal 70 is formed by the main plate
`16, tbc extending arm 18 located at a right side of tbe main
`plate 16, and tbe bridges 17 respectively located at upper and
`lower sides of the main plates 16. Additionally, the first
`terminal 70 is made of an electrically conductive metal. The
`second terminal 80, wbicb is the separate arm 19, is located
`at a left side of the first terminal 70 and spaced an appro-
`priate distance apart from the first terminal 70 and made of
`the same electrically conductive metal. The LED die 20 has
`a bottom, which is smoothly bonded to a top surface of the
`main plate 16 of tbe first terminal 70 such that an electrode
`at the bottom of the LED die 20 is electrically connected to
`the first terminal 70. The reflectfog ring 30, which is made
`of an opaque white plastic material, is molded on the top
`surface oftbe main plate 16 oftbe first terminal 70 by means
`of the injection molding technique and surrounds the die 20
`and has the inner surface 31 facing upward as a slope. The
`conductive wire 40 is connected between tbe other electrode
`of tbe top surface of the die 20 and tbe top surface of the
`second terminal 80. The encapsulant 50, which material is
`the insulated epoxy resin with high transparency, encapsu(cid:173)
`lates the die 20, tbe reflecting ring 30, and tbe conductive
`wire 40. Additionally, the base 51 of tbe encapsulant 50
`covers the top surface o[ the first terminal 70 and tlie second
`terminal 80 and fills the space therebetween to remain two
`terminals 70 and 80 spaced apart in opposite relationship.
`Tbe top of the encapsulant 50 is formed as tbe domed
`protrusion 52. When the LED package 60 is in use, generally
`take the first terminal 70 as positive electrode and the second
`terminal 80 as negative electrode such that the LEO die 20
`is charged by tbe electricity to emit white light. Tbe emitted
`35 white light is then reflected from tbe inner surface 31 of tbe
`reflecting ring 30 to the dome-shaped protrusion of the
`encapsulant 50.
`As a conclusion, the LEO die 20 has a bottom being
`smoothly bonded on the top surface of the metallic main
`40 plate 16, so that tbe contact area between the die 20 and ibe
`main plate 16 is preferably large. Moreover, the main plate
`16, more precisely, the first terminal 70 has a large bottom
`surface to be totally exposed outside, so that tbe heat
`generated by the die 20 can be conducted to the first terminal
`45 70 and further conducted ouLs;ide from the bottom surface of
`the first termina1 70 while tbe LED package 60 is charged.
`Therefore, the LED package 60 of the present invention is
`provided witb excellent efficiency of thermal dissipation so
`as to be durable for a long time.
`What is claimed is:
`1. A process for fabricating light emitting diode (LED)
`packages, comprising the steps of:
`( a) providing a plate like frame having a plurality of cells,
`each of which bas a main plate and a separate arm,
`wherein said separate arm is spaced apart from said
`maio plate with a predetermined space;
`(b) bonding an LED die on a top surface of said main plate
`of each said frame such that an electrode located at a
`bottom of said die is electrically connected to said main
`plate, and then forming a reflecting ring, which is made
`of opaque white plastic and bas an upward sloping
`inner surface, integrally on said main plate by means of
`tbe molding technique, wherein said die is surrounded
`by said reflecting ring;
`(c) connecting a conductive wire between tbe other elec(cid:173)
`trode of said die and a top surface of said separate arm
`by means of the wire boncling technique;
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`5
`(d) forming an encapsulant on each said cello( said frame
`with epoxy resio by means of the molding technique,
`wherein said eocapsulant encapsulates said die, said
`reflecting ring aod said conductive wire aod covers said
`main plate and said separate arm and fills the space
`therebetween to remain said main plate spaced apart
`from said separate arm, wherein said eocapsulaol is
`provided with a top domelike protrnsioo;
`(e) cutting said frame substantially according to the size
`of each said cell such that LEO packages are made.
`2. The process as defined in claim 1, wherein in step (b),
`booding said die is prior to forming said reflectiog ring.
`3. The process as defined in claim 1, wherein in the step
`(a), all said cells of said frame arc well arranged io the shape
`of matrix and have a plurality of openings thereon and said 15
`main plate at a center thereof, and two bridges connecting to
`
`10
`
`6
`an edge o[ said cell are respectively connected to two centers
`of two opposite lateral sides of said main plate, aod an
`extending arm connecting to an edge of said cell is coo(cid:173)
`oected to the middle of another lateral side of said maio
`5 plate, and said separate arm is located al a lateral side
`opposite lo said extending arm; in the step (b), a connecting
`bar links with two neighboring reflecting rings of the same
`row and said connecting bar is attached oo said bridges of
`said frame.
`4. The process as defined in claim 1, wherein in the step
`(b), said die is a white LED die.
`5. The process as defiocd in claim 1, wherein io the step
`(b), said sloping ioner surface of said reflecliog ring has a
`sloping angle of 45°.
`
`* * * * *
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