U.S. patent application number 10/559943 was filed with the patent office on 2006-07-13 for surface mountable light emitting device.
Invention is credited to Chan Mun Keong, Lau Yue Kwong Victor.
Application Number | 20060151800 10/559943 |
Document ID | / |
Family ID | 33098319 |
Filed Date | 2006-07-13 |
United States Patent
Application |
20060151800 |
Kind Code |
A1 |
Keong; Chan Mun ; et
al. |
July 13, 2006 |
Surface mountable light emitting device
Abstract
This invention relates to a surface mountable light emitting
device in which the lead frame is exposed over a substantial
portion of the underside of the device so as to allow greater
thermal conductivity to any device on which it may be mounted. The
LED provides the lens and a molded body to encapsulate the lead
frame and an electrical contact in a single molding step while the
lead frames and further contacts are arranged in a suitable array.
The lens couples the luminous output of a light-emitting diode
(LED) to a predominantly spherical pattern comprises a transfer
section that receives the LED's light within it and an ejector atop
it that receives light from the transfer section and spreads it
spherically. Applications may include, but are not limited to,
household light bulbs and car headlights.
Inventors: |
Keong; Chan Mun; (Hong Kong,
CN) ; Victor; Lau Yue Kwong; (Hong Kong, CN) |
Correspondence
Address: |
SINSHEIMER, SCHIEBELHUT, BAGGETT
1010 PEACH STREET
SAN LUIS OBISPO
CA
93401
US
|
Family ID: |
33098319 |
Appl. No.: |
10/559943 |
Filed: |
June 10, 2004 |
PCT Filed: |
June 10, 2004 |
PCT NO: |
PCT/US04/18387 |
371 Date: |
December 7, 2005 |
Current U.S.
Class: |
257/99 ; 257/100;
257/98; 257/E33.059 |
Current CPC
Class: |
H01L 2224/45144
20130101; H01L 2224/48247 20130101; F21K 9/61 20160801; H01L
2924/1815 20130101; F21Y 2115/10 20160801; H01L 33/486 20130101;
H01L 2924/00 20130101; H01L 2224/48095 20130101; H01L 2224/45144
20130101; F21K 9/232 20160801; H01L 33/54 20130101 |
Class at
Publication: |
257/099 ;
257/100; 257/E33.059; 257/098 |
International
Class: |
H01L 33/00 20060101
H01L033/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 13, 2003 |
US |
10/462,089 |
Claims
1. A high power surface mountable light emitting device comprising:
a light emitting semiconductor chip; a thermally and electrically
conductive lead frame connected to said chip and exposed over a
substantial portion of the underside of the device; a lead wire
from said chip to a contact exposed at least partially on a side of
said device; and a lens over said chip wherein the lens comprises:
a lower transfer section; and an upper ejector section situated
upon the lower transfer section, said lower transfer section
operable for placement upon the light emitting semiconductor chip
and operable to transfer the radiant emission to said upper ejector
section, said upper ejector section shaped such that the emission
is redistributed externally into a substantial solid angle.
2. The device of claim 1 wherein the lower transfer section is a
solid of revolution having a profile in the shape of an ellipse
with a long axis parallel to an axis of revolution of the solid and
displaced laterally therefrom so as to place the focus of said
elliptical profile on the opposite side of said axis.
3. The device of claim 2 wherein the upper ejector section is a
cylinder of the same diameter as a top diameter of the transfer
section, said cylinder having a conical depression on its top
surface.
4. The device of claim 2 wherein said lateral displacement
substantially equals the radius of said ellipsoid at its focus.
5. The device of claim 1 wherein said upper ejector section is a
conicoid.
6. The device of claim 1 wherein said upper ejector section is a
everted sphere.
7. The device of claim 1 wherein said upper ejector section is an
indented section of a sphere.
8. The device of claim 4 wherein said upper ejector section is a
cylinder.
9. The device of claim 1 wherein the upper ejector section has a
diffusive surface.
10. The device of claim 1 wherein the lens has a surface with
graded sub-wavelength roughness for reflective scattering of said
emitted light out of said device.
11. The device of claim 1 wherein the lens is made of transparent
material for distributing the radiant emission of a light emitter,
comprising an expander section for receiving said radiant emission
and narrowing its angular range to that of light guiding via total
internal reflection, and a cylindrical ejector section for
receiving said angularly narrowed radiation and ejecting it by
means of graded sub-wavelength roughness on its surface.
12. The device of claim 1 wherein said lens comprises substantially
encasement of an upper side of said chip in a transparent
compound.
13. The device of claim 12 wherein said transparent compound forms
both a lens and a portion of the body about the lead frame.
14. The device of claim 13 wherein said transparent compound is
keyed into the metallic lead frame and said contact to reduce
separation.
15. The device of claim 1 wherein said device includes a reflector
cup about said chip to reflect light from the sides of the chip
generally into a direction extending from the upper surface of said
chip.
16. The device of claim 15 wherein said reflector cup is
metallic.
17. The device of claim 15 wherein said reflector cup comprises a
core material with a highly reflective metallic coating.
18. The device of claim 17 wherein said reflective coating
comprises chromium or silver plating.
19. The device of claim 18 wherein said lead frame comprises a
substantially copper core with at least one other metal plating on
an underside thereof.
20. The device of claim 19 wherein said metal plating on said
underside of said lead frame comprises a plating of solder of
palladium.
21. The device of claim 15 wherein said transparent compound
comprises an epoxy resin.
22. The device of claim 1 wherein said lead wire to said contact is
a gold wire.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to a surface mountable light emitting
device, particularly, a surface mountable light emitting device
having a high power capacity.
[0002] Conventional light emitting diodes provide a light emitting
semiconductor chip within a metal cup, a lead wire to a further
contact on the chip, a bullet lens over the structure and a body
around the structure. Often the body would be formed integrally
with the bullet lens. Both the cup and the lead wire are attached
to legs extending from an underside of the body for connection
through a printed circuit board into a suitable circuit.
[0003] The manufacture of products that utilize large numbers of
light emitting diodes may favor the use of surface mountable
devices. The attachment of many such LEDs to, for example, a
printed circuit board holding the driving circuitry can be achieved
considerably more economically by automated machines. If such a
machine can operate on a single side of the printed circuit board
to place and secure the LED, significant savings may be made, and
the reverse side of the printed circuit board can be left free for
the provision of the driving circuitry. All of this requires a
surface mountable device that avoids the traditional placement of
the legs of the LED through a printed circuit board and soldering
on the reverse side of the board.
[0004] A variety of methods have been attempted to achieve a
suitable surface mountable light emitting device. Usually, such
methods have involved the protrusion of the lead wire and a
connection to the lead frame at the side of the device for
attachment to the surface on which it is to be mounted. Although
surface mountable, such connections are arranged around a perimeter
of the device, which limits the density at which they may be
mounted on the surface.
[0005] A further problem with light emitting devices occurs more
permanently with high power devices. An LED running at high power,
such as at one watt generates a significant amount of heat. This
heat can deteriorate the performance of the LED or, over time, lead
to the destruction or burn out of the LED.
[0006] Although the heat may be dissipated by the surrounding
apparatus, this still requires the transfer of the heat from the
source, to outside of the LED. The legs extending from the body of
the LED provide a relatively small thermal pathway, and do not
allow sufficient heat dissipation to allow high power units on the
order of one watt.
[0007] A yet further difficulty in the subject art arises in the
manufacture of LEDs. It is difficult to provide a process that
allows easy manufacture of LEDs with a minimum of components while
assuring the requirements, e.g., greater heat dissipation, of high
power units are met.
[0008] Also, conventional LEDs are optically unsuitable for direct
installation into devices such as headlamps or flashlights that use
parabolic reflectors. This is because the bullet lenses used form a
narrow beam that completely misses a nearby parabolic reflecting
surface. Using, instead, a hemispherically emitting non-directional
dome, centered on a luminous LED die, gives a maximum spread
commercially available, a Lambertian pattern. Since .theta. for a
typical parabolic flashlight reflector extends from 45.degree. to
135.degree., an LED with a hemispheric pattern is still mismatched
with respect to a parabolic reflector because the LED's emission
falls to zero at only .theta.=90.degree.. This results in a beam
that is brightest on the outside edges and completely dark halfway
in to its center. Worse yet, even this inferior beam pattern from a
hemispheric LED requires that the LED be held up at the parabola's
focal point, several millimeters above the socket wherein a
conventional incandescent bulb would be installed.
[0009] There is thus a need in the art for an effective and
optically suitable surface mountable light emitting device (LED)
that avoids the traditional placement of the legs of the LED
through a printed circuit board and soldering on the reverse side
of the printed circuit board, provides sufficient heat dissipation,
allows easy manufacture with minimum components, ensures the
requirements of high power usage are met, and is optically suitable
for direct installation into devices that use parabolic reflectors
as replacements for tungsten filament light bulbs.
SUMMARY OF THE INVENTION
[0010] The present invention advantageously addresses the needs
above as well as other needs by providing a surface mountable light
emitting device that avoids the traditional placement of legs of
the LED through a printed circuit board, and soldering of the legs
to the printed circuit board on the reverse side of the printed
circuit board, provides sufficient heat dissipation, allows easy
manufacture with minimum components, ensures the requirements of
high power usage are met, and is optically suitable for direct
installation into devices that use parabolic reflectors and
replacement of tungsten filament light bulbs.
[0011] In one embodiment, the invention can be characterized as a
high power, surface mountable light emitting device comprising a
light emitting semiconductor chip, a thermally and electrically
conductive lead frame connected to said chip and exposed over a
substantial portion of the underside of the device, a lead wire
from said chip to a contact exposed at least partially on a side of
said device and a lens over said chip.
[0012] The lens comprises a lower transfer section and an upper
ejector section situated upon the lower transfer section. The lower
transfer section is operable for placement upon the light emitting
semiconductor chip and operable to transfer the radiant emission to
said upper ejector section. The upper ejector section is shaped
such that the emission is redistributed externally into a
substantial solid angle.
[0013] A better understanding of the features and advantages of the
present invention will be obtained by reference to the following
detailed description of the invention and accompanying drawings,
which set forth an illustrative embodiment in which the principles
of the invention are utilized.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The above and other aspects, features and advantages of the
present invention will be more apparent from the following more
particular description thereof, presented in conjunction with the
following drawings wherein:
[0015] FIG. 1 is a side cross-sectional view of an optical device
according to an embodiment of the present invention;
[0016] FIGS. 2A though 2F are side cross-sectional, top
perspective, bottom perspective, side, top planar, and side
elevational views, respectively, of the lens of the optical device
of FIG. 1 according to an embodiment of the present invention;
[0017] FIGS. 3A and 3B are side perspective and bottom planar
views, respectively, of the optical device of FIG. 1;
[0018] FIG. 3C is a side perspective view of an optical device
according to an alternative embodiment of the present
invention;
[0019] FIG. 4A is a side perspective view of an optical device
according to an alternative embodiment of the present
invention;
[0020] FIG. 4B is a bottom planar view of the device of FIG.
4A;
[0021] FIG. 5A is a schematic of a driving circuit of an optical
device according to an embodiment of the present invention;
[0022] FIG. 5B is a schematic of a driving circuit of an optical
device according to an alternative embodiment of the present
invention;
[0023] FIG. 5C is a schematic of a driving circuit of an optical
device according to an alternative embodiment of the present
invention utilizing an integrated circuit;
[0024] FIG. 6 is a side cross-sectional view of a light bulb
integrating the device of FIG. 1 according to an embodiment of the
present invention; and
[0025] FIG. 7 is a partial side cross-sectional view of an optical
device according to an alternative embodiment of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIES
[0026] The following description of the presently contemplated best
mode of practicing the invention is not to be taken in a limiting
sense, but is made merely for the purpose of describing the general
principles of the invention. The scope of the invention should be
determined with reference to the claims.
[0027] Referring to FIG. 1, shown is a side cross-sectional view of
an optical device according to an embodiment of the present
invention.
[0028] Shown is a light emitting device 1 having a main body
portion 2 according to that described in Hong Kong patent
application No. 03104219.4 filed Jun. 12, 2003 for A SURFACE
MOUNTABLE LIGHT EMITTING DEVICE AND METHOD OF MANUFACTURE, the
entirety of which is hereby incorporated by reference, and lens 10
according to that described in U.S. patent application No.
60/470,691 of Minano et al., for OPTICAL DEVICE FOR LED-BASED
LIGHT-BULB SUBSTITUTE, filed May 13, 2003 (docket No. 3084.003),
and U.S. Pat. No. ______ of Minano et al., for OPTICAL DEVICE FOR
LED-BASED LIGHT-BULB SUBSTITUTE, filed Jun. 12, 2003 (docket
3084.008), the entirety of which is also hereby incorporated by
reference. The main body portion 2 has a lead frame 3, a further
contact 4, an LED semiconductor chip 6, electrical connection 7,
and portions of a transparent optical molded compound 8, 9. A lens
10 comprises a lower transfer section 11, an upper ejector section
12 and a conical indentation 13.
[0029] The lead frame 3 is located in the main body portion 2. The
LED semiconductor chip 6 is mounted on the lead frame 3. A further
contact 4 to provide the path for current through the chip 6 is
also provided and attached to the semiconductor chip 6 by an
electrical connection 7 such as a lead bonding wire. Preferably the
LED semiconductor chip is a single bond pad LED, but may also be a
double bond pad LED (which would require an additional cathode
bonding wire). The lens 10 is provided over an upper surface to
encapsulate the semiconductor chip 6 and provide preferred optical
characteristics.
[0030] As also shown in this particular embodiment, the lens 5 and
the main body portion 2 may be provided in a single molding step as
integrally molded portions from the same material using a
transparent optical molded compound. Alternatively, the lens 10 may
attach to the device 1 using optical grade glue. To act as a lens,
material used to form the lens 10 should be substantially
transparent, although not necessarily completely transparent as
there may be some desire to adapt the optical characteristics of
the output of the semiconductor chip with the lens 10. The molding
of the lens 10 and the main body portion 2 in a single integral
structure allows the transparent optical molded compound to be
keyed into the lead frame 3 and further contact 4 by the portions
of the transparent optical molded compound 8 and 9. This helps
secure the lead frame 3 and further contact 4 in place in the final
device with minimal need for adherence between the transparent
optical molded compound and the metal of the lead frame 3 and the
further contact 4.
[0031] The semiconductor chip 6 is recessed into a recess within
the lead frame 3 such that the sides of the recess act as a
reflector. The purpose of such a reflector around the semiconductor
chip 6 is to redirect light that may be emitted from the sides of
the semiconductor and reflect the light generally out through the
transparent optical molded compound 5 upwardly from the
semiconductor chip 6.
[0032] Example applications include, but are not limited to,
replacement of incandescent lights or other luminaire light sources
that are non-directional and pointed like an LED, replacement of a
flashlight bulbs, use as exterior and interior automotive lights,
use in miniature industrial light bulbs, and any other lighting
applications that require use of a pseudo filament to mimic
traditional luminaries. This may include, for example, marine
control panels or dashboard lights, avionic cockpit panel lights
and other interior lighting that utilizes miniature light
bulbs.
[0033] Referring next to FIGS. 2A through 2F, shown are side
cross-sectional, top perspective, bottom perspective, side, top
planar, and side elevational views, respectively, of the lens 10 of
the optical device 1 of FIG. 1 according to an embodiment of the
present invention.
[0034] Shown are the lens 10, lower transfer section 11, upper
ejector section 12 and conical indentation 13.
[0035] The lens 10 comprises a lower transfer section 11 and an
upper ejector section 12. The lens 10 is a substantially
transparent solid in the general shape of a prolate ellipsoid and
is a single piece of a transparent optical molded material such as
acrylic or polycarbonate. The lens 10 is preferably a rotationally
symmetric shape, larger in height than in diameter, but need not be
so (e.g., a free form shape). The upper ejector section 12 is
cylindrical, with a conical indentation 13 on top, having a core
angle of approximately 80.degree..
[0036] The lower transfer section 11 uses internal reflection to
relocate the device's 1 emission upward to a parabola's focal
point. The upper ejector section sends the transferred light out
(to a parabolic reflector, for example), sideways and downward at
angles to the axis extending all the way to at least 135.degree.,
or a little more, (measured relative to a central axis of the
ejector section, back toward the semiconductor chip 6) depending
upon the reflector. At least half the ejected light should be at
angles over 45.degree. (measured relative to a central axis of the
ejector section back toward the semiconductor chip 6), in order to
illuminate a reflector (not shown) and form a sufficiently intense
collimated beam.
[0037] In order to avoid an external reflective coating on the
surface of the transfer section 11, its geometry must promote total
internal reflection. This is why polycarbonate, with its higher
refractive index (1.5855), is preferable to acrylic (1.492). Its
correspondingly smaller critical angle, .theta.c=sin-1(1/n), of
39..degree.103 vs. 42..degree.1, reduces the height of the transfer
section from 23.5 mm to 11.6 mm.
[0038] Referring next to FIGS. 3A and 3B, shown are side
perspective and bottom planar views, respectively, of the optical
device of FIG. 1.
[0039] Shown are the light emitting device 1, the main body portion
2, the lead frame 3, the further contacts 4, the lens 10, the lower
transfer section 11, the upper ejector section 12 and the conical
indentation 13.
[0040] The further contact 4 can be seen exposed on the side of the
main body portion 2. It can also be seen in FIG. 3B that the lead
frame 3 is exposed over a substantial portion of the underside of
the device 1. This exposure of a large surface area of the lead
frame 3 on the underside of the light emitting device 1 allows
substantial heat to be drawn directly from the lead frame 3 into a
surface on which the lead frame 3 may be mounted.
[0041] Referring next to FIG. 3C shown is a side perspective view
of an optical device 1 according to an alternative embodiment of
the present invention. Shown is the light emitting device 1, main
body portion 2, further contact 4 and lens 16 comprised of an
off-axis ellipsoidal transfer section 17 and a spherical, diffusive
ejector section 18 according to that described in U.S. patent
application No. 60/470,691 of Minano et al., for OPTICAL DEVICE FOR
LED-BASED LIGHT-BULB SUBSTITUTE, filed May 13, 2003 (docket No.
3084.003), and U.S. Pat. No. ______ of Minano et al., for OPTICAL
DEVICE FOR LED-BASED LIGHT-BULB SUBSTITUTE, filed Jun. 12, 2003
(docket 3084.008).
[0042] The outer surface of the ejector section 18 has diffusive
characteristics, (i.e. surface features that cause light to
diffuse), so that each point on the ejector section 18 has a
brightness proportional to the light received from the transfer
section 17. The advantage of this kind of ejector section 18 is
that the multiple wavelengths, for example, from a tricolor LED are
mixed before they leave the ejector section 18. In the
non-diffusive ejector section 12 discussed above, which is
non-diffusive, the color mixing may be incomplete, leading to
coloration of the output beam of a parabolic reflector. The lens 16
comprises an off-axis ellipsoidal lower section 17 and an upper
spherical ejector section 18. The upper spherical ejector section
18 is smaller than the transfer section 17 (i.e., having a smaller
diameter than a middle diameter of the transfer section 17). Due to
the smaller upper spherical ejector section's size it radiates less
in angles beyond 90.degree. than if the upper spherical ejector
section 18 were larger than the transfer section 17. Such a upper
spherical ejector section will also act to mix the colors of the
red, green, and blue source chips within an LED light source.
[0043] Referring next to FIGS. 4A and 4B, shown are a side
perspective and bottom planar views, respectively of an optical
device according to an alternative embodiment of the present
invention.
[0044] Shown is the light emitting device 19, the main body portion
2, the lead frame 3, the further contacts 4, the LED components 21,
22, 23 and the lenses 10.
[0045] A plurality of individual LED components 21, 22, 23 are
incorporated into a single device 19 as shown. Each individual LED
component of the device 19 is structured and operates in the same
way as that of FIG. 1. This embodiment may be utilized where a
plurality of LEDs are necessary to provide a desired output from a
device and rather than utilizing three single LEDs fitted
individually. The surface mountable nature of the device 19 may
provide advantages in placement of all LED components on a suitable
substrate and driving mechanism such as a printed circuit board
(PCB) while still co-joined.
[0046] Naturally, it will be further appreciated that the number of
individual LEDs within the device 19 as shown in FIGS. 4A and 4B
can be 2, 3 or any other number such as shown by way of example in
FIG. 1 of Hong Kong patent application No. 03104219.4 filed Jun.
12, 2003 for A SURFACE MOUNTABLE LIGHT EMITTING DEVICE AND METHOD
OF MANUFACTURE which has been incorporated by reference.
[0047] A yet further advantage of the embodiment as shown in FIGS.
4A and 4B is that different colored LEDs can be provided. For
example, during the manufacturing process, a different chip may be
fitted to each individual LED component 21, 22 and 23. This may
allow, for example, a red, blue and green color arrangement through
the use of a different color chip in each of the individual LED
components 21, 22 and 23 so as to provide a full video color
spectrum, or the like. It will be appreciated that a variety of
other color schemes are possible.
[0048] Referring next to FIG. 5A, shown is a schematic of a driving
circuit of an optical device 6 according to an embodiment of the
present invention.
[0049] Shown is a DC/DC step-up converter 25 having a coil 26, a
resistor 27, a transistor 28, a diode 29, a capacitor 30 and an LED
6.
[0050] The step up converter (from 1V to 4V) uses +1 VDC to +3 VDC
to drive the device 6 up to 70 Ma. The coil 26 and the transistor
28 are used as a switching regulator and the resistor 27 is used as
a current control. The diode 29 provides a rectifier and the
capacitor provides a ripple filter. In this case, a single 1.5V
battery is utilized to drive the LED 6.
[0051] Referring next to FIG. 5B, shown is a schematic of a driving
circuit of an optical device 6 according to an alternative
embodiment of the present invention.
[0052] Shown is a light emitting device 1, an LED 6, a photo sensor
31, a resistor 32, a transistor 33 and a resistor 34.
[0053] The light emitting device 1 (in this case a surface
mountable diode package) circuit comprises a photo sensor 31 in die
form and the LED 6 to which a resistor 32, a transistor 33 and a
resistor 34 are connected. This allows for the LED 6 to activate
based upon varying light levels detected by the photo sensor.
[0054] Referring next to FIG. 5C, shown is a schematic of a driving
circuit of an optical device according to an alternative embodiment
of the present invention utilizing an integrated circuit.
[0055] Shown is a light emitting device 1, an LED 6 and an
integrated circuit control die 35. The integrated circuit control
die 35 is operably between the LED 6 and a power source, such as a
1.5 V DC power source, to control operation of the LED 6. The
integrated circuit control die 35 provides control, for example,
for the LED 6 to flash or blink in a pattern.
[0056] Referring next to FIG. 6, shown is a side cross-sectional
view of a light bulb, integrating the device of FIG. 1 into a light
bulb housing, according to an embodiment of the present
invention.
[0057] Shown is a light bulb 36 having the light emitting device 1
of FIG. 1 with the lens 10, the printed circuit board (PCB) 37, an
E10 lamp base 38, the wires 39 to the lamp base 38 and anode 40, an
epoxy seal 41 and a glass encasement 42.
[0058] The light emitting device 1, which acts as the optical
filament of the light bulb 36, is operably connected to the printed
circuit board 37 secured at the top of the lamp base 38. Two wires
39 are operably connected each to the lamp base 38 and anode 40 to
provide power to the light emitting device 1. The lens 10 has the
inverted cone feature shown in, for example, FIG. 1 and is located
inside the glass encasement 42 of the light bulb 36. The epoxy seal
41 is between the glass encasement 42 and the lamp base 38. The
light emitting device 1 may also be used in applications such as
exterior and interior automotive lights, wherein circuitry is
provided in the printed circuit board to draw off a 2 amp current
to drive the flasher circuit of the automobile (or whatever amount
of current happens to required for the particular application).
[0059] Referring next to FIG. 7, shown is a partial side
cross-sectional view of an optical device according to an
alternative embodiment of the present invention.
[0060] Shown is a light emitting device 1 having a main body
portion 2. The main body portion 2 is a variant of that of FIG. 1
in that it incorporates three semiconductor chips 6, 45, 47 in one
surface mountable light emitting device 1. The light emitting
device 1 has a lead frame 3, a further contact 4, electrical
connections 7, 46, 48, and portions of a compound 8, 9. A lower
transfer section 11 of the lens 10 of FIG. 1 is also partially
shown.
[0061] The lead frame 3 is located in the main body portion 2. A
plurality (three in this case) of semiconductor chips 6, 45, 47 are
mounted on the lead frame 3. A further contact 4 to provide the
path for current through the chip 6 is also provided and attached
to the semiconductor chips 6, 45, 47 by electrical connections 7,
46, 48 such as a lead bonding wires. Preferably the semiconductor
chips are single bond pad LEDs, but may also be a double bond pad
LEDs (which would require an additional cathode bonding wire). The
lens 10 (partially shown) is provided over an upper surface to
encapsulate the chips 6, 45, 47 and provide preferred optical
characteristics.
[0062] As also shown in this particular embodiment, the lens 5 and
the main body portion 2 may be provided in a single molding step as
integrally molded portions from the same material using a
transparent optical molded compound. Alternatively, the lens 10 may
attach to the device 1 using optical grade glue. To act as a lens,
the material should be substantially transparent although not
necessarily completely transparent as there may be some desire to
adapt the optical characteristics of the output of the
semiconductor chip with the lens. The semiconductor chips 6, 45, 47
are recessed into recesses within the lead frame such that sides of
the recesses act as reflectors.
[0063] While the invention herein disclosed has been described by
means of specific embodiments and applications thereof, numerous
modifications and variations could be made thereto by those skilled
in the art without departing from the scope of the invention set
forth in the claims.
[0064] All references cited herein are herein incorporated by
reference.
* * * * *