`

`Patent Application Publication Dec. 22, 2005 Sheet 1 of 14
`
`US 2005/0280017 Al
`
`20P
`\
`
`Tl
`
`50
`
`40C
`
`30
`
`20
`40
`180
`'---y--J--~------~--~Ly---J
`20A
`20B
`30B 30A
`FIG. 1
`
`20
`
`FIG. 2
`
`LOWES Ex. 1007 Page 0002
`
`

`

`Patent Application Publication Dec. 22, 2005 Sheet 2 of 14
`
`US 2005/0280017 Al
`
`20A 180
`
`20B
`
`20C 40(180)
`
`30
`
`40
`
`FIG. 3
`
`LOWES Ex. 1007 Page 0003
`
`

`

`Patent Application Publication Dec. 22, 2005 Sheet 3 of 14
`
`US 2005/0280017 Al
`
`50
`
`FIG. 4
`
`40
`30A
`81
`
`90
`
`LOWES Ex. 1007 Page 0004
`
`

`

`Patent Application Publication Dec. 22, 2005 Sheet 4 of 14
`
`US 2005/0280017 Al
`
`A I
`
`I
`
`I
`
`...
`
`' ' .
`A' 180
`
`20H
`40
`
`FIG. SA
`
`20,30
`
`30
`
`40
`
`20T(30T)
`
`20T(30T)
`
`FIG. SB
`
`LOWES Ex. 1007 Page 0005
`
`

`

`Patent Application Publication Dec. 22, 2005 Sheet 5 of 14
`
`US 2005/0280017 Al
`
`20
`
`10
`
`30
`
`30
`
`30
`
`I
`
`' ' I
`180
`
`FIG. 6
`10
`
`40
`
`4
`
`20
`
`180
`40
`FIG. 7
`
`10
`
`20
`
`180
`FIG. 8
`
`40
`
`LOWES Ex. 1007 Page 0006
`
`

`

`Patent Application Publication Dec. 22, 2005 Sheet 6 of 14
`
`US 2005/0280017 Al
`
`30
`
`30
`
`20
`
`180
`
`40
`
`FIG. 9
`
`40
`
`so
`
`20
`
`180
`
`40
`
`FIG. 10
`
`LOWES Ex. 1007 Page 0007
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`

`

`

`

`

`

`

`

`

`

`

`

`Patent Application Publication Dec. 22, 2005 Sheet 12 of 14
`
`US 2005/0280017 Al
`
`52
`
`30
`
`30
`
`' I
`I .
`180
`
`40
`
`FIG. 16
`
`606 10 50
`
`60A
`
`' I
`
`I .
`180
`
`40
`
`FIG. 17
`
`LOWES Ex. 1007 Page 0013
`
`

`

`

`

`Patent Application Publication Dec. 22, 2005 Sheet 14 of 14
`
`US 2005/0280017 Al
`
`90
`
`90A
`90C
`90B
`
`FIG. 19
`
`LOWES Ex. 1007 Page 0015
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`

`

`US 2005/0280017 Al
`
`Dec. 22, 2005
`
`1
`
`SEMICONDUCTOR LIGHT EMITTING DEVICE
`AND SEMICONDUCTOR LIGHT EMITTING UNIT
`
`CROSS-REFERENCE TO RELATED
`APPLICATIONS
`
`[0001] This application is based upon and claims the
`benefit of priority from the prior Japanese Patent Application
`No. 2004-174455, filed on Jun. 11, 2004; the entire contents
`of which are incorporated herein by reference.
`
`BACKGROUND OF THE INVENTION
`
`[0002] This invention relates to a semiconductor light
`emitting device and a semiconductor light emitting unit, and
`more particularly to a semiconductor light emitting device
`suitable to applications requiring high current drive such as
`backlights for liquid crystal displays and high power LED
`(light emitting diode) lamps, and a semiconductor light
`emitting unit with this semiconductor light emitting device
`being mounted.
`
`[0003]
`In recent years, LEDs, among other semiconductor
`light emitting devices, have shown a remarkable progress in
`technology, including white light emitting LEDs using ultra(cid:173)
`violet excitation of phosphors. Light emission of every
`display color on the CIE (International Commission on
`Illumination) coordinates has been made possible. This has
`further expanded new applications in various LED displays
`and liquid crystal display backlights, including in-vehicle
`applications (stop lamp, tail lamp, dashboard, etc.), traffic
`signals, and portable devices. The demand for device down(cid:173)
`sizing and high density packaging in these especially new
`applications requires a surface mount device (SMD) (see,
`e.g., Japanese Laid-Open Patent Application 2003-60240).
`
`[0004] The driving current for conventional SMD semi(cid:173)
`conductor light emitting devices has an upper limit of about
`50 milliamperes because they have high thermal resistance,
`and thus they can be driven only by low current. Therefore
`many LEDs must be mounted in applications requiring high
`power.
`
`[0005] On the other hand, in a high current package
`developed for power transistors, a lead frame with a die(cid:173)
`bonded chip is attached to a heat sink with an adhesive
`having high thermal conductivity, thereby addressing high
`current operation. However, this structure has room for
`improvement at the following points:
`
`[0006] 1. Thermal resistance of the adhesive layer has not
`been sufficiently reduced.
`
`[0007] 2. Many assembly steps are involved, which
`increases assembly cost.
`
`[0008] 3. The cost rises due to increase in the number of
`components (heat sink, lead frame, adhesive, etc.).
`
`[0009] Additionally, a semiconductor
`light emitting
`device with a lead frame having higher thermal conductivity
`for driving an LED at high current suffers large thermal
`stress in the solder refiow process. That is, heat for refiow is
`easier to be transmitted to the LED in the solder refiow
`process. For this reason, use of a less heat-resistant adhesive
`such as silver paste for mounting the LED may cause
`degradation in reliability including degradation in adhesion
`strength. It is thus desirable to use a highly heat-resistant
`adhesive such as eutectic solder for mounting an LED.
`
`However, conventional SMDs have another problem that it
`is difficult to mount the LED using eutectic solder because
`resin for molding the inner lead section of a lead frame has
`a low heat resistance temperature.
`
`SUMMARY OF THE INVENTION
`
`[0010] According to an aspect of the invention, there is
`provided a semiconductor light emitting device comprising:
`
`[0011] embedding resin;
`
`[0012] a first lead having a first inner lead section
`embedded in the embedding resin and a first outer
`lead section protruding from one side face of the
`embedding resin;
`
`[0013] a second lead having a second inner lead
`section embedded in the embedding resin and a
`second outer lead section protruding from a side face
`opposed to the one side face of the embedding resin;
`
`[0014] a semiconductor light emitting chip mounted
`on a portion of the first inner lead section exposed in
`a recess provided on an upper face of the embedding
`resin; and
`
`[0015] a wire connecting the semiconductor light
`emitting chip with the second lead,
`
`[0016]
`the first and second inner lead sections and the
`first and second outer lead sections each having a
`substantially coplanar rear face, and
`
`[0017] at least a part of the rear face of the first inner
`lead section and at least a part of the rear face of the
`second inner lead section being not covered with the
`embedding resin but being exposed.
`
`[0018] According to other aspect of the invention, there is
`provided a semiconductor light emitting unit comprising:
`
`[0019] a mounting substrate having a first electrode
`pad and a second electrode pad; and
`
`[0020] a semiconductor light emitting device includ(cid:173)
`ing:
`
`[0021] embedding resin;
`
`[0022] a first lead having a first inner lead section
`embedded in the embedding resin and a first outer
`lead section protruding from one side face of the
`embedding resin;
`
`[0023] a second lead having a second inner lead
`section embedded in the embedding resin and a
`second outer lead section protruding from a side
`face opposed to the one side face of the embed(cid:173)
`ding resin;
`
`[0024] a
`light emitting chip
`semiconductor
`mounted on a portion of the first inner lead section
`exposed in a recess provided on an upper face of
`the embedding resin; and
`
`[0025] a wire connecting the semiconductor light
`emitting chip with the second lead,
`
`[0026]
`the first and second inner lead sections and
`the first and second outer lead sections each hav(cid:173)
`ing a substantially coplanar rear face, and
`
`LOWES Ex. 1007 Page 0016
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`

`

`US 2005/0280017 Al
`
`Dec. 22, 2005
`
`2
`
`[0027] at least a part of the rear face of the first
`inner lead section and at least a part of the rear
`face of the second inner lead section being not
`covered with the embedding resin but being
`exposed,
`
`[0028] one of the first and second outer lead sections
`being connected with one of the first and second
`electrode pads, and
`
`[0029] other of the first and second outer lead sec(cid:173)
`tions being connected with other of the first and
`second electrode pads.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[0030] FIG. 1 is a schematic cross-sectional view illus(cid:173)
`trating the configuration of the relevant part of a semicon(cid:173)
`ductor light emitting device according to an embodiment of
`the invention.
`
`[0031] FIG. 2 is a schematic perspective view of the
`semiconductor light emitting device of the embodiment of
`the invention as viewed obliquely from above.
`
`[0032] FIG. 3 is a schematic perspective view of the
`semiconductor light emitting device of the embodiment of
`the invention as viewed obliquely from below.
`
`[0033] FIG. 4 is a schematic cross-sectional view showing
`the semiconductor light emitting device of this embodiment
`as mounted on a substrate.
`
`[0034] FIGS. SA and SB are schematic views illustrating
`the structure for enhancing bonding strength between leads
`20, 30 and resin 40.
`
`[003S] FIGS. 6 to 10 are process cross-sectional views
`illustrating the relevant part of a process of manufacturing a
`semiconductor light emitting device of this embodiment.
`
`[0036] FIG. 11 is a schematic view showing a specific
`example of a lead frame.
`
`[0037] FIG. 12 is an enlarged schematic view of the
`portion of leads 20, 30 of the lead frame illustrated in FIG.
`11.
`
`[0038] FIG. 13 is a schematic view showing a specific
`example of a lead frame with resin 40 molded thereon.
`
`[0039] FIG. 14 is an enlarged schematic view of the
`portion of the leads 20, 30 of the lead frame as illustrated in
`FIG. 13.
`
`[0040] FIGS. lSA and lSB are schematic cross-sectional
`views showing the relevant part of a first variation of the
`semiconductor light emitting device of this embodiment.
`
`[0041] FIG. 16 is a schematic cross-sectional view show(cid:173)
`ing a second variation of the semiconductor light emitting
`device of this embodiment.
`
`[0042] FIG. 17 is a schematic cross-sectional view show(cid:173)
`ing a third variation of the semiconductor light emitting
`device of this embodiment.
`
`[0043] FIGS. 18A and 18B are schematic cross-sectional
`views showing a fourth variation of the semiconductor light
`emitting device of this embodiment.
`
`[0044] FIG. 19 is a plan view showing an example of a
`mounting substrate for use in a semiconductor light emitting
`unit of this embodiment.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`[004S] Embodiments of the
`invention will now be
`described with reference to the drawings.
`[0046] FIG. 1 is a schematic cross-sectional view illus(cid:173)
`trating the configuration of the relevant part of a semicon(cid:173)
`ductor light emitting device according to an embodiment of
`the invention.
`[0047] FIG. 2 is a schematic perspective view of the
`semiconductor light emitting device as viewed obliquely
`from above.
`[0048] FIG. 3 is a schematic perspective view of the
`semiconductor light emitting device as viewed obliquely
`from below.
`
`[0049] More specifically, the semiconductor light emitting
`device of this embodiment, which is a light emitting device
`of the so-called surface mount device (SMD) type, com(cid:173)
`prises a pair of leads 20 and 30, and embedding resin 40
`formed to encompass inner lead sections 20B and 30B of the
`leads 20 and 30. A semiconductor light emitting chip 10
`(hereinafter referred to as "LED chip") is mounted on the
`lead 20. This semiconductor light emitting device can be
`mounted, for example, on an electrode pattern of various
`mounting substrates by soldering or welding outer lead
`sections 20A and 30A.
`In this embodiment, as shown in FIG. 3, the inner
`[OOSO]
`lead sections 20B and 30B of the leads have rear faces
`exposed on the bottom face (mounting surface) of the
`semiconductor light emitting device. That is, the portion of
`the lead 20 directly below the semiconductor light emitting
`chip (LED chip) 10 is not covered with the resin 40 and
`exposed.
`
`[OOSl] The exposed portion directly below the LED chip
`10 can be soldered onto a mounting substrate (not shown) to
`efficiently dissipate heat generated in the LED chip 10
`toward the mounting substrate. It should be noted that in
`FIG. 3, the resin 40 filling in anchor holes 180 is seen on the
`rear side of the semiconductor light emitting device, which
`will be described later in detail with reference to FIGS. SA
`and SB.
`
`In this embodiment, the thickness T2 of the lead 20
`[OOS2]
`measured directly below the LED chip 10 is greater than the
`thickness T3 of the tip of the outer lead section 20A (where
`it is soldered). This facilitates cooling because the greater
`thickness of metal directly below the LED chip 10 enhances
`heat sink effect. On the other hand, it is desirable that the tip
`of the outer leads 20A and 30A be not thicker than conven(cid:173)
`tional one in view of the lead cutting process and connection
`to the mounting substrate described later in detail.
`
`It should be noted that the thickness of the inner
`[OOS3]
`lead section 30B of the lead 30 does not necessarily need to
`be equal to the thickness Tl of the inner lead section 20B.
`However, with these thicknesses being comparable, wire 60
`connected from the LED chip 10 can have a comparable
`height at both ends, which facilitates wire bonding. In
`addition, the wire can be bonded in the condition that the
`
`LOWES Ex. 1007 Page 0017
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`

`

`US 2005/0280017 Al
`
`Dec. 22, 2005
`
`3
`
`bonding portion of the lead 30 is firmly supported on a stage
`of bonding apparatus, because the bonding portion of the
`lead 30 does not float in the air during wire bonding.
`
`[0054] Furthermore, when the thickness of the inner lead
`section 30B of the lead 30 is comparable to that of the inner
`lead section 20B of the lead 20, they are less prone to being
`removed from the resin 40, which enhances the mechanical
`strength of the semiconductor light emitting device.
`
`[0055] FIG. 4 is a schematic cross-sectional view showing
`a semiconductor light emitting unit having a substrate on
`which the semiconductor light emitting device of this
`embodiment is mounted.
`
`[0056] More specifically, the semiconductor light emitting
`unit of this embodiment comprises a substrate 90 such as a
`printed circuit board and a semiconductor light emitting
`device mounted thereon. Before soldering the semiconduc(cid:173)
`tor light emitting device onto the substrate 90 by solder
`refiow process, a solder pad portion is provided on the
`substrate 90, where solder paste is applied by screen printing
`or the like. The outer leads 20A and 30A are then connected
`to an electrode pattern on the substrate 90 with solder 81,
`respectively. At the same time, the portion of the lead 20
`directly below the chip is connected to the electrode pattern
`on the substrate 90 with solder 82.
`
`In this way, in this embodiment, the rear face of the
`[0057]
`pair of leads 20 and 30 has a fiat surface, which is identical
`to the mounting surface. This eliminates the need to fold or
`bend the outer leads 20A and 30A for mounting. The fiat rear
`face may be directly soldered onto the mounting surface. In
`addition, since the rear face of the leads 20 and 30 is the
`same fiat surface as the mounting surface, the soldered area
`can be made sufficiently large, which can sufficiently
`increase the mounting strength of the semiconductor light
`emitting device with respect to the mounting substrate.
`
`[0058] The semiconductor light emitting device of this
`embodiment can be bonded to the electrode pad portion of
`the substrate 90 via solder 82 because the lead directly below
`the chip is exposed on the bottom face. Heat generated by
`high current injected into the p-n junction of the LED chip
`10 is dissipated downward as shown by arrow Hl in the
`figure, and efficiently diffused into the substrate 90 as shown
`by arrow H2 via the solder bond 82 directly below the chip
`10. This allows stable, high power operation of the device
`even under high current flow. Therefore the device can be
`used in various applications including, for example, back(cid:173)
`lights of a liquid crystal display, high brightness display
`panels, in-vehicle stop lamps, tail lamps, and head lamps,
`and spotlights for toilet or other rooms, for which conven(cid:173)
`tional semiconductor light emitting units cannot provide
`sufficient illumination.
`
`In addition, in this embodiment, the thicker portion
`[0059]
`of the lead 20 has a protrusion 20P protruding from the resin
`40. The protrusion 20P thus provided serves to decrease the
`thermal resistance of the path shown by arrow H3. That is,
`part of the heat dissipated from the LED chip 10 can be
`efficiently diffused into the substrate 90 via solder 81 under
`the outer lead 20A as shown by arrow H4. Furthermore, the
`protrusion 20P can facilitate heat dissipation into the air as
`shown by arrow HS because it is not covered with the resin
`40.
`
`In the following, the configuration of various parts
`[0060]
`of the semiconductor light emitting device of this embodi(cid:173)
`ment will be described in more detail with reference to
`FIGS. 1 to 4.
`
`[0061] The inner lead section 20B of the lead 20 has a
`cup-shaped recess 20C. On the other hand, the embedding
`resin 40 has a recess 40C, at the bottom of which are
`exposed in part the inner lead sections 20B and 30B includ(cid:173)
`ing the recess 20C of the lead. The LED chip 10 is die
`bonded to the bottom face of the recess 20C of the lead 20.
`Eutectic solder, conductive paste, or gold (Au) bump can be
`used as an adhesive for die bonding. The electrode of the
`LED chip 10 is connected to the other inner lead section 30B
`via bonding wire 60.
`
`[0062] The cup-shaped recess 20C has a slanted sidewall,
`which has a function of reflecting the light emitted from the
`LED chip 10. The sidewall of the recess 40C of the embed(cid:173)
`ding resin 40 also has a reflecting function. As a result, the
`light extraction efficiency can be improved. When the side(cid:173)
`wall of the recess 20C is formed in an R-shaped or other
`curved configuration, the light reflectance is increased and
`high light extraction efficiency is achieved while maintain(cid:173)
`ing desired light distribution characteristics.
`
`In this respect, placing the LED chip 10 near the
`[0063]
`center of the recess 20C facilitates obtaining uniform light
`distribution characteristics. The recess 40C provided in the
`embedding resin 40 may comprise a first conical portion
`centered on the LED chip 10 and a second conical portion
`additionally provided for housing the wire 60 as shown in
`FIG. 2, for example. The recess 40C formed in this way can
`efficiently reflect upward the light emitted from the LED
`chip 10 and increase the light extraction efficiency.
`
`[0064] On the other hand, as described later in detail,
`during insert molding process using the embedding resin 40,
`the mold for resin can be prevented from contacting the LED
`chip 10 as a result of housing the LED chip 10 in the recess
`20C. That is, the embedding resin 40 can be insert molded
`after the LED chip 10 is mounted on the lead 20. Conse(cid:173)
`quently, as an additional advantageous effect, eutectic solder
`or other adhesives having a high melting point can be used
`for bonding the LED chip 10.
`
`[0065] The LED chip 10 may be any of various visible
`light LED chips. Furthermore, various emission colors
`including white light can be obtained by combining ultra(cid:173)
`violet LED chips with phosphors as appropriate. In this way,
`every color represented by the spectral luminous efficiency
`curve defined in the CIE (International Commission on
`Illumination) standard can be realized.
`
`[0066] The recess 40C of the embedding resin 40 encom(cid:173)
`passing the LED chip 10 and the bonding wire 60 is filled
`with sealing resin 50. It should be noted that in FIG. 2, the
`sealing resin 50 is omitted for revealing the internal struc(cid:173)
`ture.
`
`[0067] When the LED chip 10 is a chip made of InGaAlP(cid:173)
`based compound semiconductor that emits red or other
`visible light, the sealing resin 50 may be made of epoxy
`resin, for example.
`
`[0068] On the other hand, when the LED chip 10 is a chip
`that emits ultraviolet radiation, it is desirable that the sealing
`resin 50 be made of silicone-based resin. This is because
`
`LOWES Ex. 1007 Page 0018
`
`

`

`US 2005/0280017 Al
`
`Dec. 22, 2005
`
`4
`
`epoxy resin may be discolored by ultraviolet irradiation,
`while silicone-based resin is not discolored and maintains
`high light transmittance over time. In addition, a desired
`emission color is obtained by mixing phosphors in the
`sealing resin SO as appropriate.
`
`It is desirable that the pair of leads 20 and 30 be
`[0069]
`formed from metal. For example, copper (Cu) based alloy
`may be advantageously used for obtaining high thermal
`conductivity. Coating its surface by plating or other process
`serves to increase the light reflectance at the sidewall of the
`cup-shaped recess 20C and the bonding strength of solder on
`the rear face of the outer lead sections 20A and 30A and of
`the lead 20 directly below the chip 10. Such coating may
`include, for example, silver (Ag), or nickel (Ni)/palladium
`(Pd)/gold (Au) laminated in this order. For silver coating, the
`thickness may be about 10 micrometers, for example. For
`the latter laminated structure, the thickness may be, for
`example, about 1 micrometer for nickel, about 0.03
`micrometer for palladium, and about 0.008 micrometer for
`gold. Such coating can increase reflectance at the recess 20C
`and bonding strength of soldering.
`
`[0070] The thickness Tl of the inner lead sections 20B and
`30B may be about 1.2 millimeters, for example. The thick(cid:173)
`ness T2 of the portion of the recess 20C where the LED chip
`10 is mounted may be about 0.7 millimeter, for example.
`The thickness T3 of the outer lead sections 20A and 30A
`may be about 0.5 millimeter, for example. The LED chip 10
`may have a square shape of 1 millimeter per side, for
`example, for high power type.
`
`[0071] The embedding resin 40 may be made of thermo(cid:173)
`plastic resin, for example. Such resin may include nylon(cid:173)
`based resin such as polyphthalamide (PPA), for example.
`The leads 20 and 30 can be insert molded using such
`thermoplastic embedding resin 40.
`
`[0072] Use of thermoplastic resin for the embedding resin
`40 results in high heat resistance and reliability. For
`example, use of epoxy resin for the embedding resin 40
`slightly decreases heat resistance during solder reflow pro(cid:173)
`cess and reliability for temperature cycle. This is because the
`thermal expansion coefficient of epoxy resin is much greater
`than that of metal constituting the leads. For this reason, if
`epoxy resin is used, expansion of heated epoxy resin may
`result in a problem of peeloff of the LED chip and/or
`disconnection of wire.
`
`In contrast, use of thermoplastic resin for the
`[0073]
`embedding resin 40 improves heat resistance during solder
`reflow and reliability for temperature cycle. In particular,
`when titanium oxide or other filler is mixed in thermoplastic
`resin such as polyphthalamide, the thermal expansion coef(cid:173)
`ficient can be decreased and softening at the time of heating
`can be prevented. For example, mixing of filler including
`titanium oxide at about 30 to 40 percent by weight results in
`a semiconductor light emitting device having extremely
`good heat resistance.
`
`[0074] Furthermore, mixing or blending of reflective
`material in the embedding resin 40 can facilitate the reflect(cid:173)
`ing effect at the sidewall of the recess 40C. For example,
`potassium titanate powder may be preferably mixed in the
`resin 40.
`
`[007S] With regard to the outer dimensions of the embed(cid:173)
`ding resin 40, for example, the length L may be about 7
`
`millimeters, the width W may be about 5 millimeters, and
`the height H may be about 2 millimeters.
`
`[0076] On the other hand, this embodiment is based on the
`structure in which the rear face of the leads 20 and 30 is
`exposed at the bottom face of the embedding resin 40. It is
`therefore desirable to use a structure having increased bond(cid:173)
`ing strength to avoid peeloff of these leads from the embed(cid:173)
`ding resin 40.
`
`[0077] FIGS. SA and SB are schematic views illustrating
`the structure for enhancing bonding strength between leads
`20, 30 and resin 40.
`
`[0078] More specifically, anchor holes 180 are provided
`through the lead 20 (30) so that the embedding resin 40 may
`fill in these anchor holes 180. This serves to reduce "loos(cid:173)
`ening" between the leads and the injection molded object
`and to increase adhesion strength and contact area, so that
`peeloff of the leads from the resin 40 can be prevented.
`
`[0079] Moreover, asperities 20H and 30H can be provided
`at the tip of the inner lead sections of the lead 20 and 30 to
`improve "biting" to the resin 40, so that the bonding strength
`can be enhanced.
`
`[0080] Furthermore, as shown as line A-A' cross section in
`FIG. SB, a tapered portion 20T (30T) with its width decreas(cid:173)
`ing toward the rear face may be provided on the sidewall of
`the lead 20 (30). This facilitates supporting the lead 20 (30)
`with the tapered portion 20T (30T) obliquely from below,
`thereby preventing peeloff of the resin 40.
`
`[0081] The anchor holes 180, asperities 20H (30H), and
`tapered portion 20T (30T) described above can be formed by
`presswork of the leads 20 and 30. They serve to reduce
`"loosening" between the leads and the injection molded
`object and to increase adhesion strength and contact area, so
`that peeloff of the leads from the resin 40 can be prevented.
`
`In the following, the semiconductor light emitting
`[0082]
`device of this embodiment will be described in more detail
`with reference to a method of manufacturing the same.
`
`[0083] FIGS. 6 to 10 are process cross-sectional views
`illustrating the relevant part of a process of manufacturing a
`semiconductor light emitting device of this embodiment.
`
`[0084] First, as shown in FIG. 6, the LED chip 10 is
`mounted on the recess 20C of the lead 20. It is desirable that
`the leads 20 and 30 be supplied in the form of the so-called
`"lead frame".
`
`[008S] FIG. 11 is a schematic view showing a specific
`example of such a lead frame.
`
`[0086] FIG. 12 is an enlarged schematic view of the
`portion of a pair of leads 20, 30 of the lead frame illustrated
`in FIG. 11.
`
`[0087] The lead frame of this specific example has anchor
`holes 180, asperities 20H (30H), and tapered portion 20T
`(30T) as described above with reference to FIGS. SA and
`SB. The anchor hole 180 is provided on the side face of the
`lead 20 as a notch.
`
`[0088] The LED chip 10 can be die bonded with silver
`paste, eutectic solder (AuSn, Au Ge, AuSi, etc.), or gold (Au)
`bump. For a high power (also high current) LED, it is
`desirable to use adhesive material resistant to high tempera(cid:173)
`ture operation because the p-n junction temperature is
`
`LOWES Ex. 1007 Page 0019
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`US 2005/0280017 Al
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`Dec. 22, 2005
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`5
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`increased. For this reason, it is desirable to use eutectic
`solder or gold bump that achieves stable bonding strength at
`high temperatures. For example, since AuSn has a melting
`temperature of about 280° C., it is more reliable during high
`temperature operation than silver paste. Mounting with
`AuSn eutectic solder is often carried out at about 320° C.
`
`[0089] After the LED chip 10 is mounted, embedding
`resin 40 is then insert molded.
`
`[0090] FIG. 7 shows a lead frame inserted into a molding
`die 140 for resin 40.
`
`In this embodiment, the LED chip 10 is housed in
`[0091]
`the recess 20C of the lead 20. This allows insert molding
`without contact of the molding die 140 with the LED chip
`10. That is, the resin 40 can be insert molded after the LED
`chip 10 is mounted.
`
`[0092] The embedding resin 40 made of thermoplastic
`resin such as PPAhas a heat resistance temperature of about
`290° C. In this respect, use of eutectic solder requires the
`bonding temperature to be as high as about 320° C. That is,
`it is difficult to mount the LED chip 10 with eutectic solder
`after the embedding resin 40 is insert molded.
`
`In contrast, according to the present embodiment,
`[0093]
`the LED chip 10 is mounted in the recess 20C of the lead.
`This allows insert molding without contact of the molding
`die 140 with the chip 10. As a result, die bonding with
`eutectic solder at high temperature can be followed by insert
`molding of resin. Therefore eutectic solder, which has high
`thermal reliability, can be used without thermal deterioration
`of the resin 40.
`
`[0094] FIG. 8 shows the lead frame pulled out of the
`molding die 140 after completing insert molding.
`
`[0095] FIG. 13 is a schematic view showing a specific
`example of a lead frame with resin 40 molded thereon.
`
`[0096] FIG. 14 is an enlarged schematic view of the
`portion of the leads 20, 30 of the lead frame as illustrated in
`FIG. 13.
`
`In this way, a lead frame with a plurality of leads
`[0097]
`20, 30 arranged in parallel can be inserted into the molding
`die 140 to form resin 40 all at once.
`
`[0098] Subsequently, as shown in FIG. 9, the electrode
`(not shown) provided on the LED chip 10 is wire bonded via
`gold (Au) or other wire to the inner lead section 30B of the
`lead 30 exposed at the bottom of the recess 40C of the resin.
`
`[0099] Next, as shown in FIG. 10, the LED chip 10 and
`the wire 60 are sealed by filling the recess 40C of the
`embedding resin 40 with resin.
`
`[0100] Subsequently, a series of semiconductor light emit(cid:173)
`ting devices linked by the lead frame are individually
`separated by lead cutting to complete the manufacturing
`process. Automation of manufacturing apparatuses (die
`bonder, wire bonder, molding machine, lead cutter, etc.)
`used in various steps of the above process can ensure high
`productivity and reliability.
`
`[0101] The semiconductor light emitting device and a
`method of manufacturing the same according to the embodi(cid:173)
`ment of the invention have been described. In the following,
`variations of the semiconductor light emitting device of this
`embodiment will be described.
`
`[0102] FIGS. 15A and 15B are schematic cross-sectional
`views showing the relevant part of a first variation of the
`semiconductor light emitting device of this embodiment.
`
`[0103] More specifically, as shown in FIG. 15A, the depth
`D of the recess 20C may be greater than the thickness of the
`LED chip 10. As described earlier, this serves to protect the
`LED chip 10 against the molding die 140. In addition, the
`light emitted from the LED chip 10 is reflected at the
`sidewall of the recess 20C and can be extracted upward.
`
`[0104] Furthermore, as shown in FIG. 15B, a salient
`portion 100 is provided around the chip 10 in the recess 20C
`and its outside is filled with reflective material 200. This
`serves to efficiently reflect the light laterally emitted from
`the chip 10 and the light can be extracted upward as shown
`by arrows in the figure. For example, the reflective material
`200 may include fine particles of potassium titanate. Such
`fine particles can be mixed in the resin for infilling to
`efficiently reflect the light emitted from the LED chip 10.
`More specifically, the light extraction efficiency can be
`significantly increased because of the reflecting position
`closer to the chip 10 than in the case of reflecting at the
`sidewall of the recess 20C as shown in FIG. 15A, and
`because of high reflectance of the material 200.
`
`[0105] FIG. 16 is a schematic cross-sectional view show(cid:173)
`ing a second variation of the semiconductor light emitting
`device of this embodiment.
`
`[0106] This variation includes first sealing resin 52 for
`sealing the LED chip 10 and second sealing resin 54 for
`further sealing its outside.
`
`[0107] For example, the first sealing resin 52 may be
`mechanically soft resin having relatively low hardness. This
`serves to reduce mechanical stress applied to the LED chip
`10 and to alleviate the problem of crack and peeloff. In this
`case, the second sealing resin 54 may be made of resin
`having high mechanical strength to withstand application of
`external force and impact.
`
`In addition, for example, the LED chip 10 may be
`[0108]
`an ultraviolet light emitting chip, the first sealing resin 52
`may be silicone resin containing phosphors dispersed
`therein, and the second sealing resin 54 may be epoxy resin.
`Ultraviolet radiation emitted from the LED chip 10 is
`wavelength converted by phosphors contained in the first
`sealing resin 52 into visible light, for example. This visible
`light transmits through the second sealing resin made of
`epoxy resin and can be extracted outside. Since ultraviolet
`radiation is wavelength converted by phosphors, the second
`sealing resin 54 made of epoxy resin does not suffer from
`discoloration or other problems. Furthermore, use of the
`epoxy resin for the material of the second sealing resin 54
`serves to improve durability against application of external
`force and impact.
`
`[0109] FI