United States Patent [191
`
`[11] Patent Number:
`5,298,768
`[45] Date of Patent: Mar. 29, 1994
`Okazaki et a1.
`
`Illlllllllllll|l||||||||||||||||llllllllllllllllllll|l|||||||||||l|||||||||
`U5005298768A
`
`[54] LEADLESS CHIP-TYPE LIGHT EMITTING
`ELEMENT
`
`[75]
`
`Inventors:
`
`Jun Okazaki, Tondabayashi;
`Muaaki Katoh, Osaka, both of Japan
`
`[73] Assignee:
`
`Slurp Kahushiki Kaisha, Osaka,
`Japan
`
`[21] Appl. No.: 998,746
`
`[22] Filed:
`
`Dec. 30, 1992
`
`Foreign Application Priority Data
`[30]
`Feb. 14, 1992 [JP]
`Japan .................................... 4.28477
`Jun. 15, 1992 [JP]
`Japan ............. 4-154846
`
`
`[51]
`Int. Cl.5 ...................................... H01L 33/00
`[52] US. Cl. ................... 257/81; 257/82;
`257/88; 257/91; 257/99; 257/100
`[58] Field of Search ..................... 257/99, 100, 91, 88,
`257/98, 81, 82
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`4,013,915 3/1977 Dufft .............................. 257/99 XR
`
`7/1991 Waitl et a1. ............... 350/9620
`5,035,483
`5,089,861
`2/1992 Tanaka et al.
`...............
`257/99 XR
`
`FOREIGN PATENT DOCUMENTS
`
`59-119777 7/1984 Japan ..................................... 257/99
`60—]37076
`7/1985 Japan............. 257/99
`60—43040 9/1985 Japan .
`62-85481
`4/1987 Japan ..................................... 257/99
`2-229477 9/1990 Japan ................................... 257/100
`
`Primaor Examiner—William Mintel
`
`[57]
`
`ABSTRACT
`
`A light emitting element having a cavity at the center of
`the top surface of an insulating block body. A through-
`hole extends downward through the block body to the
`bottom of the cavity. A metallic layer is present on the
`sides and bottom of the cavity, the sides of the through-
`hole, the bottom surface and part of the side surfaces of
`the block body. An LED chip is disposed on the metal-
`lic layer to the side of the bottom of the cavity. The
`LED chip and the metallic layer formed on a side of the
`bottom of the cavity separate from the first side are
`connected by a metallic wire. The cavity and the
`through-hole are filled with resin for encapsulating the
`LED chip.
`
`23 Claims, 10 Drawing Sheets
`
`
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`Cree Ex. 1005
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`Page 1
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`US. Patent
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`Mar. 29, 1994
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`Sheet 1 of 10
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`5,298,768
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`US. Patent
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`Mar. 29, 1994
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`Sheet 2 of 10
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`5,298,768
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`FIG.3
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`US. Patent
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`Mar, 29, 1994
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`Sheet 3 of 10
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`5,298,768
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`FIG.5
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`US. Patent
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`Mar. 29, 1994
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`Sheet 4 of 10
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`US. Patent
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`Mar. 29, 1994
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`Sheet 5 of 10
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`FIG.9
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`US. Patent
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`Mar. 29, 1994
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`Sheet 6 of 10
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`5,298,768
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`FIGJO
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`US. Patent
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`Mar. 29, 1994
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`Sheet 7 of 10
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`5,298,768
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`Mar. 29, 1994
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`Sheet 3 of 10
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`Mar. 29, 1994
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`Sheet 9 of 10
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`Mar. 29, 1994
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`Sheet 10 of 10
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`5,298,768
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`FIGJG
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`1
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`LEADLESS CHIP-TYPE LIGHT EMITTING
`ELEMENT
`
`FIELD OF THE INVENTION
`
`The present invention relates to a light emitting ele-
`ment, for example, chip LEDs (light emitting diodes)
`used as back light for liquid crystal displays, a light
`array in facsimile machines, and as a display member in
`various kinds of operation panels.
`
`BACKGROUND OF THE INVENTION
`
`Various types of chip LEDs have been developed.
`For example, the following four types of chip LEDs are
`generally known. A chip LED of type I is formed by
`molding a fiberglass-reinforced epoxy resin substrate
`having a metallic layer. A chip LED of type II is
`formed with the use of a lead frame by transfer-molding
`the epoxy resin. A chip LED of type III is formed by
`insert-molding a casein a lead frame in advance and by
`filling the case with the epoxy resin after mounting an
`LED chip. A chip LED of type IV is formed by form-
`ing a case in a fiberglass-reinforced epoxy resin sub-
`strate and filling the case with the epoxy resin like type
`III. In addition to these types of chip LEDs, as dis-
`closed in the Japanese Publication for Unexamined
`Patent Applications, No.
`107283/ 1980
`and No.
`283883/1989, there are LED lamps which are produced
`by forming a wiring pattern in a three dimensional man-
`ner on an injection-molded resin, without using a lead
`frame.
`
`As for the chip LED of type 1, since the difference in
`the linear expansion coefficient between the fiberglass-
`reinforced epoxy resin substrate (7 to l X10"6/°C.) and
`the epoxy resin (4 to 6XlO-5/°C.) is great, they are
`likely separated when heat is applied, for example, in
`soldering. In addition, the fiberglass-reinforced epoxy
`resin substrate isflat and the chip LED of this type does
`not have a reflecting case structure, resulting in an LED
`lamp with poor luminous intensity.
`As for the chip LEDs of type III and type IV, since
`these chip LEDs have reflecting cases, the light emitted
`by their LED chips is effectively directed in the upper
`direction. However, they have a drawback in terms of
`adhesion of the lead frame and the case or adhesion of
`the fiberglass-reinforced epoxy resin substrate and the
`case, and are not resistant to high temperatures in so]-
`dering like type 1. Furthermore, with respect to types
`III and IV, insert-molding the casein the lead frame and
`bonding of the case to the substrate respectively in-
`crease the manufacturing costs.
`As for the chip LED of type II, since it does not have
`a reflecting case, the light emitted by the LED chip is
`scattered in the forward direction and therefore the
`light is not efficiently directed in the upper direction.
`On the other hand, the chip LEDs disclosed in the
`Japanese Publication for Unexamined Patent Applica-
`tions, No. 107283/1980 and No. 283883/ 1989, have an
`insulating block body. Each block body has a reflecting
`case (a cavity) in the form of a recess at the center in its
`top surface. The sides of the cavity slope. The cavity,
`top surface, side surfaces and part of the bottom surface
`of the block body are covered with a pair of electrode
`patterns (plated layer). In such chip LEDs, the reflect-
`ing case and the electrode patterns are united. This
`arrangement
`therefore overcomes the problem,
`i.e.,
`insufficient adhesion of the lead frame and reflecting
`
`10
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`15
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`20
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`25
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`case, associated with the above-mentioned chip LEDs
`using lead frames, and reduces the manufacturing costs
`However,
`in the chip LEDs having the electrode
`patterns formed on the insulating block body by plating,
`when sealing the cavities in a substrate whereon a num—
`ber of chip LEDs are produced, an epoxy resin is
`dropped into each cavity. Therefore, even if a small
`amount of the epoxy resin overflows from a cavity, the
`resin flows to the bottom of the block body through its
`through-hole which is necessary for chemical plating
`and for forming electrodes on the top and bottom sur-
`faces of the substrate. When the epoxy resin flows to the
`bottom of the block body, soldering cannot be per-
`formed properly in mounting the chip LED as a prod-
`uct. This problem is solved by increasing the capacity of
`the cavity. However, the cavity with an increased ca-
`pacity causes an increase in the size of the chip LED.
`The resulting chip LED does not meet demand for
`smaller and thinner chip LEDs. Therefore, the chip
`LED is always formed with a cavity of the minimum
`possible capacity. Consequently, the resin must be
`poured into each cavity on the substrate with precision.
`To increase the light emission efficiency of the LED
`lamp, the sides of the cavity must slope at a small angle
`between 30° and 70°. However, if the cavity becomes
`shallower, the epoxy resin more likely overflows. The
`reason for this is that the viscosity of the epoxy resin
`momentary decreases during heat curing and it spreads
`around the cavity when it comes to a level higher than
`the brim of the cavity.
`Moreover, if the cavity is shallow, the adhesion of the
`epoxy resin and reflecting case becomes weaker and the
`epoxy resin and the reflecting case are easily separated
`from each other when heat is applied, for example, in
`soldering. Namely, when the cavity is formed in the
`above-mentioned shape, the light emission efficiency
`and the quality of the product improve. However, this
`causes complicated manufacturing processes and an
`increase in the manufacturing costs.
`In the meantime, the chip LED is mounted on and
`electrically joined to one of the electrode patterns, and
`is connected to the other electrode pattern with a metal-
`lic wire.
`
`In a chip LED of this type, since the respective elec-
`trodes are formed over the entire side surfaces of the
`block body and on the surface of the cavity in which the
`translucent resin is poured, solder may climb the side
`surfaces of the electrodes to the top surface of the LED
`in surface-mounting. As a result, the appearance of the
`product after mounted, and the quality of the translu-
`cent resin deteriorate. Moreover, when the electrodes
`are formed in the above-mentioned manner, they con-
`sume a large amount of solder, causing so-called Man-
`hattan Phenomena (in which the chip part falls over).
`
`SUMMARY OF THE INVENTION
`
`An object of the present invention is to improve light
`emission efficiency and product quality of a light emit-
`ting element while reducing the number of components
`and the manufacturing costs.
`the light
`To achieve the above-mentioned object,
`emitting element of the present invention has at least the
`following means:
`(a) an insulating substrate having at the center of the
`top surface thereof a cavity with sides sloping outward
`toward the top and a through-hole formed in the bot-
`tom of the cavity, the through-hole extending down-
`ward through the insulating substrate;
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`5,298,768
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`3
`(b) a first electrode which is formed to continuously
`cover a first side of the cavity, the through-hole, the
`bottom surface and part of the first side surface of the
`substrate;
`(c) a second electrode which is formed to continu-
`ously cover a second side of the cavity, the through-
`hole, the bottom surface and part of the second side
`surface of the substrate, the second side of the cavity
`facing the first side of the cavity, the second side surface
`of the substrate facing the first side surface of the sub-
`strate;
`(d) light emitting means, electrically joined to the
`first electrode, for emitting light when electricity is
`conducted;
`(e) connecting means for electrically connecting the
`light emitting means to the second electrode; and
`(f) translucent sealing means for filling the cavity and
`the through-hole.
`In the light emitting element, the through—hole which
`is necessary for forming the electrodes is incorporated
`in the substrate by forming in the bottom of the cavity
`a hole extending downward through the substrate and
`by continuously forming the first and second electrodes
`on the cavity,
`the through-hole, and on the bottom
`surface and part of the side surfaces of the substrate.
`This arrangement enables a reduction in the number of
`components. Moreover, since the above-mentioned
`through-hole functions as an air vent when filling the
`cavity and the through-hole with the sealing means, the
`cavity and the through-hole are firmly sealed up.
`When surface-mounting the light emitting element by
`soldering, solder does not climb the electrodes because
`the first and second electrodes are formed over only
`part of the side surfaces of the substrate. It is thus possi-
`ble to prevent the appearance of the product from dete-
`riorating and the Manhattan phenomena which occur
`when a large amount of solder is consumed.
`For a fuller understanding of the nature and advan-
`tages of the invention, reference should be made to the
`ensuing detailed description taken in conjunction with
`the accompanying drawings.
`
`BRIEF DESCRIPTION OF THE DRAWING
`
`FIG. 1 is a plan view of a chip LED according to one
`embodiment of the present invention.
`FIG. 2 is a bottom view of the chip LED.
`FIG. 3 is a front view of the chip LED.
`FIG. 4 is a side view of the chip LED.
`FIG. 5 is a profile of the chip LED cut across the line
`E—E.
`
`FIG. 6 is a profile of the chip LED cut across the line
`F—F.
`
`FIG. 7 is a view explaining the thermal stress of an
`epoxy resin constituting the chip LED.
`FIG. 8 is a profile of the chip LED soldered.
`FIG. 9 is a plan view showing an allocation of the
`chip LEDs in a substrate.
`FIG. 10 is a perspective view showing how the resin
`is sealed in the substrate.
`
`FIG. 11 is a plan view showing cutting lines on the
`substrate.
`
`IO
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`15
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`20
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`25
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`30
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`35
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`40
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`45
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`50
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`55
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`4
`FIG. 16 is a profile of the chip LED cut across the
`line H—H.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`
`Embodiment I
`
`The following description discusses a first embodi-
`ment of the present invention with reference to FIGS. 1
`through 11. In this embodiment, a chip LED is adopted
`as a light emitting element.
`As shown in FIGS. 1 through 6, the main compo-
`nents of the chip LED relating to this embodiment are
`an insulating block body 4, a pair of metallic layers, 18
`and 19, an LED chip 1, a metallic wire 3, and a translu-
`cent resin 11.
`
`The insulating block body 4 has a cavity 20 and a
`through-hole 21, formed in the bottom of the cavity 20,
`extending downward through the insulating block body
`4. The sides of the cavity 20 slope outward toward the
`top.
`The metallic layer 18 is formed by continuously plat-
`ing the side and bottom 7 of the cavity 20, the side 6 of
`the through-hole 21, and the bottom surface and part of
`the side surface S of the block body 4. Meanwhile, the
`metallic layer 19 is formed by plating the side and bot-
`tom of the cavity 20, the side 9 of the through-hole 21,
`and the bottom surface and part of side surface 10 of the
`block body 4. The metallic layer 19, located on the left
`in FIG. 6, and the metallic layer 18 are substantially
`symmetrical and electrically separated from each other.
`The LED chip 1 is fixed on (electrically joined to) the
`bottom 8 of the cavity 20 with a conductive paste 2, and
`is electrically connected to the bottom 7 of the cavity 20
`with the metallic wire 3.
`
`Next, the structure of the chip LED and process for
`manufacturing the chip LED are briefly described be-
`low.
`
`Firstly, the insulating block body 4 is formed by a
`heat-resistant resin. For example, a liquid crystal poly-
`mer, PPS, PBS, or other material generally used for
`manufacturing LEDs is employed. Secondly, the cavity
`20 on which the LED chip 1 is to be mounted is formed
`in the insulating block body 4. Thirdly, the through-
`hole 21 is made on the bottom of the cavity 20 to go
`through the bottom surface of the insulating block body
`4.
`
`Next, a pair of metallic layers, 18 and 19, are formed
`on the block body 4. On the side of the block body 4
`where the LED chip 1 is to be mounted, for example,
`the metallic layer 19 is formed to continuously cover
`the side (reflecting surface) and bottom (chip-mount
`portion) 8 of the cavity 20, the side 9 of the through-
`hole 21, and the bottom surface and part of the side
`surface 10 of the block body 4. In the same manner, the
`metallic layer 18 is formed to cover the side and bottom
`7 of the cavity 20, the side 6 of the through-hole 21, and
`the bottom surface and part of the side surface 5 of the
`block body 4.
`After the pair of the metallic layers, 18 and 19, are
`formed, the LED chip 1 is bonded onto the metallic
`layer 19 on the bottom of the cavity 20 with the conduc-
`tive paste 2, and is connected to the metallic layer 18
`with the metallic wire 3.
`Then, the cavity 20 and the through-hole 21 are filled
`with a translucent resin such as an epoxy resin to form
`a translucent resin section 11. To prevent leakage of the
`translucent resin from the through-hole 21, the block
`
`FIG. 12 is a plan view of a chip LED according to
`the alternative embodiment of the present invention.
`FIG. 13 is a front view of the chip LED of FIG. 12.
`FIG. 14IS a side view of the chip LED.
`FIG. 15'1s a profile of the chip LED cut across the
`line G—G.
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`body 4 is fixed on a heat-resistant sticky tape such as a
`glass cloth tape 12 as shown in FIG. 6. The glass cloth
`tape 12 is peeled off after hardening the resin to com-
`plete the product.
`The translucent resin section 11 occupies the cavity
`20 and the through-hole 21, in particular, from a portion
`of the cavity 20 forming a reflecting case in the proxim-
`ity of the LED chip 1 to the bottom surface of the
`product. In contrast to the sides of the cavity 20, the
`sides of the through-hole 21 slope outward toward the
`bottom.
`
`The translucent resin section 11 thus formed brings
`about the following effects. For example, in the case
`when the insulating block body 4 is formed by a liquid
`crystal polymer and when an epoxy resin is used to form
`the translucent resin section 11, the expansion coeffici-
`ent of the epoxy resin is greater than that of the liquid
`crystal polymer. Namely, the expansion coefficient of
`the liquid crystal polymer is 2 to 4X10—5/°C. and that
`of the epoxy resin is 5 to 7X10—5/°C.
`Consequently, forces acting on the directions A and
`B are produced as shown in FIG. 7. More specifically,
`since the force in the A direction is weakened by the
`force in the B direction in the through-hole 21 (the
`epoxy resin section formed in the shape of a wedge with
`respect to the cavity), the epoxy resin and the liquid
`crystal polymer adhere to one another. If there is no
`force exerted in the B direction, the product expands
`and shrinks repeatedly. This may cause the epoxy resin
`section and the liquid crystal polymer section to be
`partly or completely separated from each other at the
`boundaries, 7 and 8, and the metallic wire 3 to be dis-
`connected.
`
`10
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`15
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`20
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`25
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`30
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`6
`side surfaces 5 and 10 of the block body 4. The reason
`for not covering the entire side surfaces of the block
`body 4 with the metallic layers is related to the process,
`to be discussed later, performed for preventing leakage
`of the epoxy resin when filling the cavity 20 and the
`through-hole 21 with the epoxy resin.
`Next, the following description discusses the advan-
`tages of the processes of manufacturing chip LEDs.
`FIG. 9 shows the substrate for the chip LEDs of this
`embodiment. When using an MID (molded intercon-
`nection device) technique in which an electric circuit is
`formed on a molded product by chemical plating, sev-
`eral products may be manufactured on a substrate since
`the insulating sections (block bodies 4) are formed by
`injection molding. This technique enables the products
`to be processed at a time in each of the subsequent
`processes and a reduction in the manufacturing costs.
`Each cavity 20 on the substrate forms a product.
`Firstly, the LED chip 1 is fixed to each of the cavities
`20 on the substrate, shown in FIG. 9, with the conduc-
`tive paste 2, and is wired with the metallic wire 3.
`Then,
`to prevent
`leakage of the resin from the
`through-hole 21 when sealing the cavity 20 and the
`through-hole 21 with the resin, a heat-resistant sticky
`tape such as the glass cloth tape 12 is attached to the
`bottom surface of the substrate. The following method
`is commonly used in sealing. In this method, the cavities
`20 and the through-holes 21 are filled with the resin by
`dropping the resin into each cavity 20 one by one using
`a dispenser (a resin discharger). In this method, how-
`ever, even if a plurality of dispensers are used for a
`substrate, the resin must be dropped into each cavity 20
`one by one. Thus, a long time is required when a num-
`ber of products are made on the substrate. In addition,
`the substrate, disclosed in the above-mentioned Japa-
`nese Publication for Unexamined Patent Application
`283883/ 1989, has the through-hole which goes through
`the substrate from the top surface to the bottom surface.
`Therefore, if the level of precision with respect to pour-
`ing a resin into cavities is low, the resin leaks from the
`bottom, resulting in defective products. Furthermore,
`the substrate must be carefully handled until the resin
`introduced into the cavities is hardened otherwise the
`resin leaks if the substrate tilts.
`FIG. 10 shows how the resin is sealed in the cavities
`20 according to the chip LEDs of this embodiment. The
`bottom surface of the substrate (on which, for example,
`an array of 16 LEDs in 4~dotX4—dot patterns are pro-
`duced as shown in the drawing) is secured with the
`glass cloth tape 12. Then, the four sides of the substrate
`is positioned and fixed by fixing members such as silicon
`rubber substrates 16. Next, the epoxy resin is dropped
`into the cavities 20. At this time, the epoxy resin can be
`continuously dropped into the respective cavities 20
`without the need for careful precision, i.e., the cavities
`20 can brim over.
`
`After filling the cavities 20, a Spatula 17 is moved in
`the directions of the arrows shown in the drawing over
`the surface of the substrate. Since the overflown resin
`runs into the cavities 20 which are not completely filled
`with the resin when the spatula 17 is moved, the surface
`is levelled. Namely, an excess of the resin is supplied
`and the excess is scraped out by the spatula 17. In conse-
`quence, by comparison with a conventional method in
`which the resin must be poured into each cavity with
`precision, with the use of the substrate of this embodi-
`ment casting is performed with precision in a shorter
`time.
`
`As described above, in the chip LED of this embodi-
`ment, the epoxy resin for sealing fills the space from the
`top of the cavity 20 through the through-hole 21 to the
`bottom of the liquid crystal polymer section. Addition-
`ally, since the epoxy resin section is formed in the shape
`of wedges engaging with each other in the space in the
`liquid crystal polymer section, the chip LED is very
`stable under thermal stress.
`Furthermore, it is generally known that, when the
`chip LED is used as an LED lamp, light emission effi-
`ciency is increased by making the sides of the cavity 20
`slope at a small angle between 30° and 70“ rather than
`90'. If the sides slope within this range, the luminous
`intensity in the forward (upper) direction is increased.
`However, the adhesion of the epoxy resin and liquid
`crystal polymer deteriorates as the sloping angle be-
`comes smaller, causing the epoxy resin section to easily
`come off from the liquid crystal polymer section. To
`overcome such a problem,
`in the chip LED of this
`embodiment, the through-hole 21 extending downward
`to the bottom surface of block body 4 is formed in the
`shape of a wedge. This arrangement enables increased
`light emission efficiency of the LED lamp while pre-
`venting the adhesion of the epoxy resin section and
`liquid crystal polymer section from deteriorating.
`FIG. 8 schematically shows a soldering state of the
`chip LED of this embodiment. Numeral 13 represents a
`substrate on which the block body 4 is surface-mounted,
`numeric 14 is the wiring, and numeric 15 represents
`soldered sections. When the metallic layers are formed
`only on the bottom surfaces of the block body 4 for
`soldering, if the substrate 13 is warped, the soldered
`portion 15 may be detached. To prevent such a prob-
`lem, in this embodiment, the metallic layers are formed
`not only on the bottom surfaces but also on part of the
`
`35
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`In order to reduce the manufacturing costs, it is desir-
`able to increase the number of products produced on a
`substrate. As the number of products produced on a
`substrate increases, the above-mentioned method pro-
`duces more favorable effects.
`For instance, if a resin discharging nozzle is installed
`in front of the spatula 17, it is possible to pour the resin
`into the cavities 20 and to level off the resin with a
`single motion. This arrangement enables casting to be
`performed with less precision needed in a shorter time
`in comparison to a conventional arrangement using a
`dispenser.
`After the casting, the substrate is cut along the lines C
`and D shown in FIG. 11 to produce the chip LEDs of
`FIG. 6.
`
`5
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`10
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`15
`
`Embodiment 2
`
`With reference to FIGS. 12 through 16, a second
`embodiment of the present invention is described be-
`low.
`
`20
`
`8
`tions as would be obvious to one skilled in the art are
`intended to be included within the scope of the follow-
`ing claims.
`What is claimed is:
`
`1. A light emitting element comprising:
`an insulating substrate having a cavity at the center of
`a top surface thereof and a through-hole formed in
`the bottom of said cavity, sides of said cavity slope
`outward toward the top surface, said through-hole
`extending downward through said insulating sub-
`strate to a bottom surface;
`a first electrode which is formed to continuously
`cover a first side of said cavity, a first portion of
`said through-hole, a first portion of said bottom
`surface and a first side surface of said substrate,
`wherein the first electrode does not cover the en-
`tire portion of said first side surface;
`a second electrode which is formed to continuously
`cover a second side of said cavity, a second portion
`of said through-hole, a second portion of the bot-
`tom surface and a second side surface of said sub-
`strate, said second side of said cavity facing said
`first side of said cavity, said second side surface of
`said substrate facing said first surface of said sub-
`strate, wherein the second electrode does not cover
`the entire portion of said second side surface;
`light emitting means, electrically joined to said first
`electrode, for emitting light when electricity is
`conducted;
`connecting means for electrically connecting said
`light emitting means to said second electrode; and
`translucent sealing means for filling said cavity and
`said through hole.
`2. The light emitting element according to claim 1,
`wherein said through-hole has sides which slope out-
`ward toward the bottom surface of the insulating sub-
`strate.
`
`25
`
`3O
`
`35
`
`As shown in FIGS. 12 through 16, a chip LED of this
`embodiment has an insulating block body 31 made of a
`resin substrate for three dimensional wiring. The insu-
`lating block body 31 is produced from a highly heat-
`resistant resin including a liquid crystal polymer by
`injection molding. The chip LED is mass-produced
`through the following processes. Firstly, the insulating
`block bodies 31 are arranged in a matrix, and are wired
`in a three dimensional manner. Then, die bonding and
`wire bonding are performed. The resin sections are
`molded. Finally, each of the chip LEDs are separated
`by a dicing saw.
`Formed on the surface of each block body 31 is a
`cavity having sloping sides. The cavity is plated with
`silver or gold to form a metallic layer 32. A through-
`hole 40 extending vertically through the block body 31
`is symmetrically formed on each side of the bottom of
`the metallic layer 32. The shape of the through-hole 40
`is substantially square when it is seen from above.
`Formed at the bottom part of the side surfaces of the
`block body 31 are electrodes 33 for soldering. An elec-
`trode separator 34 is formed by performing masking
`before plating, or by performing etching after plating.
`The electrode separator 34 separates anode from cath-
`ode. An LED chip 35 is die-bonded onto one side of the
`metallic layer 32 thus separated and is connected to the
`other side of the metallic surface with a metallic wire
`36. Then, the cavity is filled up with an epoxy resin 37.
`In FIGS. 12 and 16, sections 38 and 39 shown in
`check patterns are resist sections on which a resist ink is
`applied. More specifically,
`the first resist section 38
`located at the peripheral of the block body 31 indicates
`the polarity of the electrode and prevents the overflow
`of the epoxy resin 37. When the chip LED is surface-
`mounted by soldering in a reflow furnace, the second
`resist section 39 located at the center on the bottom,
`(back) surface of the block body 31 prevents short cir-
`cuit of the chip during soldering by insulating the anode
`and the cathode from each other.
`The chip LED with the above-mentioned structure
`efficiently emits a beam of light from the LED chip 35
`through a reflecting case (not shown) surrounding the
`LED chip 35. It is therefore possible to produce highly-
`bright LED lamps by using chip LEDs.
`The invention being thus described, it will be obvious
`that the same may be varied in many ways. Such varia-
`tions are not to be regarded as a departure from the
`spirit and scope of the invention, and all such modifica-
`
`3. The light emitting element according to claim 1,
`wherein said insulating substrate is formed of a heat-
`resistant resin.
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`4O
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`50
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`55
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`65
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`4. The light emitting element according to claim 1,
`wherein said first and second electrodes are formed by
`plating.
`5. The light emitting element according to claim 1,
`wherein said light emitting means is a light emitting
`diode chip mounted to the bottom of said cavity with a
`conductive paste.
`6. The light emitting element according to claim 1,
`wherein said connecting means is a metallic wire.
`7. The light emitting element according to claim 1,
`wherein said sealing means is an epoxy resin.
`8. The light emitting element according to claim 1,
`wherein a pair of through-holes are formed, one of said
`through-holes being respectively formed on the first
`and second sides of said cavity.
`9. The light emitting element according to claim 8,
`wherein said insulating substrate has resist sections, said
`resist sections being formed by depositing a resist ink
`onto the top edge of said substrate and the bottom sur-
`face of said insulating substrate between said through
`holes.
`
`10. The light emitting element according to claim 1,
`wherein the sides of said cavity slope outward toward
`the top surface of the insulating substrate at an angle of
`less than 90' with respect to the bottom of the cavity for
`reflecting light emitted from said light emitting element
`toward the top surface of said insulating substrate
`through said translucent sealing means.
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`11. The light emitting element according to claim 10,
`wherein the sides of the through-hole slope in a direc-
`tion outward toward the bottom of the insulating sub-
`strate at an angle of less than 90° for stabilizing the
`internal forces within the translucent sealing means 5
`which fills the cavity and the through-hole.
`12. The light emitting element according to claim 1,
`wherein the first side surface includes a first recessed
`portion extending along a portion of said first side sur-
`face for receiving the first electrode so that the first 10
`electrode does not extend along the entire length of the
`first side surface; and
`the second side surface includes a recessed portion
`extending along a portion of said second side sur-
`face for receiving the second electrode so that the
`second electrode does not extend along the entire
`length of the second side surface.
`13. The light emitting element according to claim 8,
`wherein said through-hole has sides which slope out-
`ward toward the bottom surface of the insulating sub-
`strate.
`
`15
`
`20
`
`10
`toward the top surface of said insulating substrate
`through said translucent sealing means.
`20. The light emitting element according to claim 11,
`wherein the sides of the through-hole slope in a direc-
`tion outward toward the bottom of the insulating sub-
`strate at an angle of less than 90° for stabilizing the
`internal forces within the translucent sealing means
`which fills the cavity and the through-hole.
`21. The light emitting element according to claim 20,
`wherein the first side surface includes a first recessed
`portion extending along a portion of said first side sur-
`face for receiving the first electrode so that the first
`electrode does not extend along the entire length of the
`first side surface; and
`the second side surface includes a recessed portion
`extending along a portion of said second side sur-
`face for receiving the second electrode so that the
`second electrode does not extend along the entire
`length of the second side surface.
`22. The light emitting element according to claim 8,
`wherein said first elec