U.S. patent application number 15/052346 was filed with the patent office on 2016-06-16 for led module.
The applicant listed for this patent is ROHM CO., LTD.. Invention is credited to Masahiko KOBAYAKAWA.
Application Number | 20160172563 15/052346 |
Document ID | / |
Family ID | 44861652 |
Filed Date | 2016-06-16 |
United States Patent
Application |
20160172563 |
Kind Code |
A1 |
KOBAYAKAWA; Masahiko |
June 16, 2016 |
LED MODULE
Abstract
A lead 1 includes a die-bonding portion 11 with an opening 11a
penetrating in a thickness direction. Another lead 2 is spaced from
the lead 1. An LED unit 3 includes an LED chip 30 with a electrode
terminal 31 connected to the lead 1 and another electrode terminal
32 connected to the lead 2. The LED unit 3, mounted on a surface of
the die-bonding portion 11 on a first side in z direction, overlaps
the opening 11a. A wire 52 connects the lead 2 and the electrode
terminal 32. A support member 4 supporting the leads 1-2 is held in
contact with another surface of the die-bonding portion 11 on a
second side in z direction. These arrangements ensure efficient
heat dissipation from the LED chip 30 and efficient use of light
emitted from the LED chip 3.
Inventors: |
KOBAYAKAWA; Masahiko;
(Kyoto-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ROHM CO., LTD. |
Kyoto-shi |
|
JP |
|
|
Family ID: |
44861652 |
Appl. No.: |
15/052346 |
Filed: |
February 24, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14531420 |
Nov 3, 2014 |
9312462 |
|
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15052346 |
|
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13695206 |
Oct 29, 2012 |
8890203 |
|
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PCT/JP2011/060436 |
Apr 28, 2011 |
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14531420 |
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Current U.S.
Class: |
257/98 |
Current CPC
Class: |
H01L 33/647 20130101;
H01L 2224/48465 20130101; H01L 2924/01322 20130101; H01L 33/641
20130101; H01L 2924/01322 20130101; H01L 2224/73265 20130101; H01L
2224/45144 20130101; H01L 2924/00 20130101; H01L 2224/45144
20130101; H01L 33/62 20130101; H01L 2924/00 20130101; H01L 33/60
20130101 |
International
Class: |
H01L 33/64 20060101
H01L033/64; H01L 33/62 20060101 H01L033/62; H01L 33/60 20060101
H01L033/60 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 30, 2010 |
JP |
2010-104768 |
Claims
1-8. (canceled)
9. An LED module comprising: a support member having a first edge
and a second edge that extend in a first direction and a second
direction, respectively, in plan view, the second direction being
perpendicular to the first direction; a first lead supported by the
support member; a first LED chip disposed on and electrically
connected to the first lead; a second lead supported by the support
member and spaced apart from the first lead in the first direction;
and a second LED chip disposed on and electrically connected to the
second lead; wherein the first lead includes: a first metal portion
on which the first LED chip is mounted; and a first protruding
portion connected to the first metal portion and protruding from
the first metal portion toward the second lead in the first
direction, the second lead includes: a second metal portion facing
the first protruding portion; and a second protruding portion
connected to the second metal portion and on which the second LED
chip is mounted, the second protruding portion facing the first
metal portion and protruding, from the second metal portion toward
the first lead in the first direction, and the first protruding
portion and the second protruding portion are spaced apart from
each other and overlap with each other as viewed in the second
direction.
10. The LED module according to claim 9, further comprising a first
wire having, a first end and a second end, wherein the first end of
the first wire is attached to the second LED chip, the second end
of the first wire is attached to the second lead, and the first
wire extends from the second LED chip to be further away from the
first LED chip in the first direction.
11. The LED module according to claim 9, wherein the first LED chip
and the second LED chip have respective portions that do not
overlap with each other as viewed in the first direction.
12. The LED module according claim 9, wherein at least a part of
the second LED chip faces the first metal portion in the first
direction.
13. The LED module according to claim 9, wherein the first metal
portion and the second protruding portion have respective edges
that are parallel to each other.
14. The LED module according to claim 9, wherein the second metal
portion and the first protruding portion have respective edges that
are parallel to each other.
15. The LED module according to claim 9, further comprising a frame
member surrounding the first LED chip and the second LED chip.
16. The LED module according to claim 15, further comprising a
resin filled in a space defined by the frame member, wherein the
resin covers the first LED chip and the second LED chip while
allowing passage of light emitted from each of the first LED chip
and the second LED chip.
17. The LED module according to claim 10, further comprising a
second wire having a first end and a second end, wherein the first
end of the second wire is attached to the second LED chip.
18. The LED module according to claim 17, wherein the first end of
the first wire and the first end of the second wire are disposed at
respective positions that are different in distance from the first
LED chip in plan view.
19. The LED module according to claim 18, wherein the second LED
chip has a shape of an elongated rectangle in plan view, and the
first end of the first wire and the first end of the second wire
are spaced apart from each other in a longitudinal direction of the
second LED chip.
20. The LED module according to claim 15, wherein the second
protruding portion of the second lead has an extension that extends
at least to the frame member in plan view.
21. The LED module according to claim 16, wherein the space defined
by the frame member has a rectangular shape elongated in the first
direction in plan view.
22. The LED module according to claim 16, wherein the frame member
has an inclined surface facing the space, and the resin is in
contact with the inclined surface.
23. The LED module according to claim 17, further comprising a
third wire having a first end and a second end, wherein the first
end of the third wire is attached to the second metal portion of
the second lead, and the second end of the third wire is
electrically connected to another wire other than the second
lead.
24. The LED module according to claim 23, further comprising a
fourth wire having a first end and a second end, wherein the first
end of the fourth wire is attached to the first LED chip, and the
fourth wire extends in a direction that is non-parallel to the
first direction in plan view.
25. The LED module according to claim 24, wherein the second end of
the fourth wire is spaced apart from the second LED chip.
26. The LED module according to claim 24, wherein a distance in
plan between the first and the second ends of the fourth wire is
greater than a distance between the first protruding portion and
the second protruding portion in the second direction.
27. The LED module according to claim 15, wherein the first lead
includes an extension extending away from the first protruding
portion in the first direction, and the extension extends at least
to the frame member in plan view.
28. The LED module according to claim 27, wherein the first metal
portion of the first lead is greater in size measured in the second
direction than the extension of the first lead.
Description
[0001] This application is a Continuation of U.S. Ser. No.
14/531,420, filed Nov. 3, 2014, which is a Continuation of U.S.
Ser. No. 13/695,206 filed Oct. 29, 2012, which is a National Stage
Application of PCT/JP2011/060436, filed Apr. 28, 2011, which
applications are incorporated herein by reference.
TECHNICAL FIELD
[0002] The present invention relates to an LED module incorporating
an LED chip.
BACKGROUND ART
[0003] FIG. 12 shows an example of conventional LED module (see
Patent Document 1, for example). In the LED module X shown in FIG.
12, an LED unit 92 is mounted at the center on an obverse surface
of a substrate 91 by using a bonding material, not shown. The
substrate 91 is an insulating substrate made of a ceramic material
such as alumina or alumina nitride. The LED unit 92 is connected to
leads 94 and 95 by wires 93. The LED module X further includes a
resin cover 96 made of a transparent epoxy resin and covering the
LED unit 92 and the wires 93. For instance, the LED unit 92 is made
transparent.
[0004] In the LED module X, the obverse surface of the substrate 91
is made white so that light traveling through the reverse surface
of the LED unit 92 toward the obverse surface of the substrate 91
is reflected. This assures that light emitted from the LED unit 92
is efficiently utilized.
[0005] However, when the LED unit 92 is directly mounted on the
substrate 91, heat generated during light emission of the LED unit
92 is not easily dissipated as compared with the case where the LED
unit 92 is mounted on a wiring pattern made of a metal, for
example. On the other hand, although a wiring pattern made of a
metal is an excellent heat dissipator, its surface may change to a
dark color as time elapses. Such color change hinders efficient
utilization of light from the LED unit 92.
TECHNICAL REFERENCE
Patent Document
[0006] Patent Document 1: JP-A-11-112025
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0007] The present invention has been conceived under the
circumstances described above. It is therefore an object of the
present invention to provide an LED module that can efficiently
dissipate heat from the LED chip incorporated in it and efficiently
utilize light emitted from the LED chip.
Means for Solving the Problems
[0008] According to a first aspect of the present invention, there
is provided an LED module comprising: a first lead including a
die-bonding portion formed with an opening penetrating in a
thickness direction; a second lead spaced apart from the first
lead; an LED unit including an LED chip provided with a first
electrode terminal and a second electrode terminal, the first
electrode terminal being electrically connected to the first lead,
the second electrode terminal being electrically connected to the
second lead, the LED unit being mounted on a surface of the
die-bonding portion on a first side in the thickness direction in a
manner overlapping the opening at least partially; a wire
connecting the second lead and the second electrode terminal to
each other; and a support member supporting the first and the
second leads and held in contact with a surface of the die-bonding
portion on a second side in the thickness direction.
[0009] According to this arrangement, heat generated during light
emission of the light-emitting element is readily transferred to
the die-bonding portion and released to the outside through the
first lead. Further, part of the light emitted from the
light-emitting element toward the die-bonding portion side in the
thickness direction is reflected by the white support member
filling the opening. Thus, the light-emitting element module of the
present invention exhibits both high heat dissipation and high
brightness.
[0010] According to a second aspect of the present invention, in
the LED module of the first aspect, at least part of the opening
overlaps a part of the LED chip as viewed in the thickness
direction.
[0011] According to a third aspect of the present invention, in the
LED module of the first or second aspect, the support member is
made of a white resin.
[0012] According to a fourth aspect of the present invention, in
the LED module of the third aspect, the opening is filled with a
part of the support member.
[0013] According to a fifth aspect of the present invention, in the
LED module of any one of the second through the fourth aspects, the
opening is smaller than the LED chip as viewed in the thickness
direction, and the entirety of the opening is included in the LED
chip.
[0014] According to a sixth aspect of the present invention, in the
LED module of any one of the second through the fourth aspects, the
opening includes a portion that does not overlap the LED chip as
viewed in the thickness direction.
[0015] According to a seventh aspect of the present invention, in
the LED module of the sixth aspect, the first and the second
electrode terminals are provided on an end surface of the LED chip
disposed on the first side in the thickness direction, and the
opening includes an edge disposed on a side in a direction
perpendicular to a direction in which the wire extends, where the
edge of the opening is arranged not to overlap the LED chip as
viewed in the thickness direction.
[0016] According to an eighth aspect of the present invention, in
the LED module of the fifth or sixth aspect, the second electrode
terminal is provided on a first end surface of the LED chip in the
thickness direction, and the first electrode terminal is provided
on a second end surface of the LED chip in the thickness
direction.
[0017] Other features and advantages of the present invention will
become more apparent from detailed description given below with
reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a plan view showing an LED module according to a
first embodiment of the present invention;
[0019] FIG. 2 is a sectional view taken along lines II-II in FIG.
1;
[0020] FIG. 3 is a graph showing the relationship between the
performance and the area of an opening of the LED module shown in
FIG. 1;
[0021] FIG. 4 is an enlarged plan view showing a principal portion
of another example of the LED module shown in FIG. 1;
[0022] FIG. 5 is a plan view showing an LED module according to a
second embodiment of the present invention;
[0023] FIG. 6 is a plan view showing an LED module according to a
third embodiment of the present invention;
[0024] FIG. 7 is a plan view showing an LED module according to a
fourth embodiment of the present invention;
[0025] FIG. 8 is a sectional view taken along lines VIII-VIII in
FIG. 7;
[0026] FIG. 9 is a plan view showing an LED module according to a
fifth embodiment of the present invention;
[0027] FIG. 10 is a sectional view taken along lines X-X in FIG.
9;
[0028] FIG. 11 is a sectional view showing an LED module according
to a sixth embodiment the present invention; and
[0029] FIG. 12 is a perspective view showing a conventional LED
module.
MODE FOR CARRYING OUT THE INVENTION
[0030] Preferred embodiments of the present invention are described
below with reference to the accompanying drawings.
[0031] FIGS. 1 and 2 show an LED module according to a first
embodiment of the present invention. The LED module A1 of this
embodiment includes a lead 1, a lead 2 spaced apart from the lead
1, and an LED unit 3 electrically connected to each of the leads 1
and 2, and is designed such that the LED chip 3 emits light due to
connection of the leads 1 and 2 to an external electric circuit.
The LED unit 3 is connected to the lead 1 by a wire 51 and
connected to the lead 2 by a wire 52. The LED module A1 further
includes a support member 6 for fixing the leads 1 and 2, and a
protective member 7 for protecting the LED unit 3. In FIG. 1,
illustration of the protective member 7 is omitted. The LED module
A1 is in the form of an elongated rectangle with a longer side
extending in the x direction and a shorter side extending in the y
direction, as viewed in the z direction.
[0032] The lead 1 includes a die-bonding portion 11 having an
opening 11a, and a terminal portion 12 extending from the
die-bonding portion 11. The lead 1 is made by punching a copper
plate which is 0.15 to 0.20 mm in thickness to form an opening 11a,
and then plating the surface with silver.
[0033] The die-bonding portion 11 is a portion for mounting the LED
unit 3. The opening 11a is provided adjacent to the center of the
die-bonding portion 11 in the y direction. The position, shape and
size of the opening 11a can be set appropriately in the punching
process. The opening 11a in this embodiment is in the form of a
rectangle having a dimension of 0.3 mm in the x direction and a
dimension of 0.2 mm in the y direction. As shown in FIG. 2, the
opening 11a is filled with the support member 6.
[0034] The terminal portion 12 is exposed to the outside from one
end of the support member 6 in the x direction and is used to
connect the lead 1 to an external electric circuit. The terminal
portion 12 is formed by bending a portion of the lead 1 which
projects from the support member 6 after the support member 6 is
formed.
[0035] As shown in FIGS. 1 and 2, the lead 2 includes a
wire-bonding port ion 21 spaced apart from the die-bonding portion
11 in the x direction, and a terminal portion 22 extending from the
wire-bonding portion 21. The lead 2 is formed by e.g. plating a
copper plate which is 0.15 to 0.20 mm in thickness with silver. The
terminal portion 22 is exposed to the outside from another end of
the support member 6 in the x direction and is used to connect the
lead 2 to an external electric circuit. The terminal portion 22 is
formed by bending a portion of the lead 2 which projects from the
support member 6 after the support member 6 is formed.
[0036] The LED unit 3 comprises an LED chip 30 made by forming a
layer of a semiconductor material such as gallium nitride on a
surface of a substrate made of e.g. sapphire (Al2O3 single
crystal). The LED chip 30 emits blue light, green light, red light
or the like due to recombination of electrons and holes in an
active layer sandwiched between an n-type semiconductor layer and a
p-type semiconductor layer. Since the light emitted is hardly
absorbed by the sapphire substrate in the LED unit 3, the light is
emitted in almost all directions. As viewed in the z direction, the
LED unit 3 is in the form of an elongated rectangle having a
dimension of 0.8 mm in the x direction and a dimension of 0.4 mm in
the y direction. As shown in FIG. 1, the LED unit 3 is bonded to
the die-bonding portion 11 by using a bonding material 4 so as to
overlap the opening 11a as viewed in the z direction. In this
embodiment, the LED unit 3 is arranged to close the opening 11a.
The bonding material 4 is e.g. a transparent epoxy resin.
[0037] To fix the LED unit 3 to the die-bonding portion 11, a
bonding material 4 is first applied to a region of the die-bonding
portion 11 on which the LED unit 3 is to be mounted, and then the
LED unit 3 is placed on the bonding material 4.
[0038] The LED unit 3 has, on the upper end surface in the z
direction, an electrode terminal 31 at one end in the x direction
and an electrode terminal 32 at another end in the x direction. The
electrode terminal 31 is connected to an n-type semiconductor layer
and electrically connected to the die-bonding portion 11 via a wire
51. The electrode terminal 32 is connected to a p-type
semiconductor layer and electrically connected to the wire-bonding
portion 21 via a wire 52. The wires 51 and 52 may be gold
wires.
[0039] The support member 6 is made of a white epoxy resin in which
e.g. titanium oxide is mixed and has a generally rectangular shape
in plan view, as shown in FIG. 1. The support member 6 fixes the
leads 1 and 2 by covering part of each lead. The support member 6
is recessed at the center and has a reflective surface 61 that is
inclined to become further away from the LED unit 3 in the x
direction as proceeding upward in the z direction. As shown in FIG.
1, the reflective surface 61 is in the form of a frame surrounding
the LED unit 3, as viewed in the z direction. The reflective
surface 61 serves to reflect the light emitted from the LED unit 3
in a direction perpendicular to the z direction upward in the z
direction. The support member 6 having the above-described
structure is made by insert molding using a mold. Specifically, the
support member 6 is formed by setting the leads 1 and 2 in a mold,
pouring liquid epoxy resin into the mold and then hardening the
resin. According to this method, liquid epoxy resin flows into the
opening 11a, so that the opening 11a is filled with part of the
support member 6. When epoxy resin does not flow into the entire
portion of the opening 11a and only part of opening 11a is filled
with the support member 6, transparent bonding material 4 may be
supplied into the opening 11a.
[0040] The protective member 7 is formed to fill the region
surrounded by the reflective surface 61 and covers the die-bonding
portion 11, the wire-bonding portion 21, the LED unit 3 and the
wires 51, 52. For instance, the protective member 7 is made of a
transparent epoxy resin.
[0041] The advantages of the LED module A1 are described below.
[0042] According to this embodiment, since the LED unit 3 is
mounted on the lead 1 made of a metal, heat generated during light
emission of the LED unit 3 is readily transferred to the lead 1.
Since the terminal portion 12 of the lead 1 is exposed to the
outside of the support member 6, heat transferred to the lead 1 is
readily released to the outside air. Thus, the LED module A1
exhibits high heat dissipation performance, and hence deterioration
of the LED unit 3 due to temperature rise is prevented, thereby
providing enhanced reliability.
[0043] Moreover, according to this embodiment, part of the light
emitted from the LED unit 3 downward in the z direction is
reflected by the white support member 6 filling the opening 11a to
travel upward in the z direction. In this way, the presence of the
white support member 6 under the LED unit 3 provides a higher
reflectivity than when the underside of LED unit 3 is entirely
covered by the lead 1 made of a metal. Thus, in the LED module A1,
light traveling downward in the z direction is efficiently turned
into light traveling upward in the z direction. Thus, the LED
module A1 can utilize light from the LED unit 3 with a high
efficiency close to the efficiency provided when the LED unit 3 is
placed on a white non-metal material, while having high heat
dissipation performance due to the use of the metal lead 1.
[0044] FIG. 3 shows the relationship between the area of the
opening 11a as viewed in the z direction and the heat dissipation
performance of the LED module A1 or use efficiency of the light
emitted from the LED unit 3. As shown in FIG. 3, as the area of the
opening 11a increases, the use efficiency of light from the LED
unit 3 increases, while the heat dissipation performance of the LED
module A1 reduces. The area of the opening 11a as viewed in the z
direction is determined according to the application of the LED
module A1 or the performance of the LED unit 3. In an example in
which the area of the opening 11a is smallest, the opening 11a is
in the form of a square as viewed in the z direction, with each
side of the square corresponding to the thickness of the lead 1. In
an example in which the area of the opening 11a is largest, the
opening 11a just overlaps the LED unit 3 in the z direction.
[0045] The opening 11a may be divided e.g. as shown in FIG. 4.
Moreover, the opening 11a may not be merely divided but may
comprise combination of a plurality of through-holes.
[0046] Other embodiments of the present invention are described
below. In these figures, the elements that are identical or similar
to those of the foregoing embodiment are designated by the same
reference signs as those used for the foregoing embodiment, and the
description is omitted appropriately.
[0047] FIG. 5 shows an LED module A2 according to a second
embodiment of the present invention. The LED module A2 has a
die-bonding portion 11 formed with an opening 11b larger than the
opening 11a of the foregoing embodiment. The structures of other
parts are the same as those of the LED module A1.
[0048] The opening 11b is in the form of a rectangle whose
dimension in the y direction is larger than the dimension in the y
direction of the LED unit 3. As shown in FIG. 5, in the y
direction, the LED unit 3 is flanked by two edges of the opening
11b which are spaced from each other in the y direction. Similarly
to the opening 11a, the opening 11b is filled with the support
member 6.
[0049] In this embodiment, heat generated during light emission of
the LED unit 3 is transferred to the die-bonding portion 11 from
the two ends of the LED unit 3 which are spaced from each other in
the x direction. Thus, the LED module A2 exhibits high heat
dissipation performance.
[0050] At the two ends of the LED unit 3 which are spaced from each
other in the x direction are arranged the electrode terminals 31
and 32. Therefore, from these end portions, light is unlikely to be
emitted upward in the z direction. In this embodiment, the
underside of the LED unit 3 in the z direction is white almost
entirely except the above-described portions from which light is
unlikely to be emitted upward in the z direction. Thus, in the LED
module A2, light emitted from the LED unit 3 downward in the z
direction is turned into light traveling upward in the z direction
with an efficiency close to the efficiency provided when the LED
unit 92 is placed on a white substrate 91, as is in the
conventional LED module X. Thus, the LED module A2 can utilize
light from the LED unit 3 with high efficiency, while retaining
high heat dissipation performance.
[0051] FIG. 6 shows an LED module A3 according to a third
embodiment of the present invention. The LED module A3 has a
die-bonding portion 11 formed with an opening 11c in the form of a
cutout. The structures of other parts are the same as those of the
LED module A1.
[0052] The opening 11c extends downward from the upper edge of the
die-bonding portion 11 in the y direction in FIG. 6. The opening
11c is also filled with the support member 6.
[0053] The LED module A3 also exhibits high heat dissipation
performance because part of the LED unit 3 is held in contact with
the die-bonding portion 11 made of a metal. Further, the white
support member 6 filling the opening 11c functions to efficiently
turn the light emitted from the LED unit 3 downward in the z
direction to light traveling upward in the z direction.
[0054] FIGS. 7 and 8 show an LED module A4 according to a fourth
embodiment of the present invention. The LED module A4 includes
leads 1A, 1B, 1C, 2A, 2B and 2C, LED units 3A, 3B and 3C, a support
member 6, a protective member 7, and two Zener diodes 8. The LED
module A4 is configured as a side-view LED module that emits light
mainly in the z direction.
[0055] The leads 1A, 1B, 1C, 2A, 2B and 2C are made of copper and
plated with silver, for example.
[0056] The lead 1A includes a die-bonding portion 11, terminal
portions 12, and a thin, elongated strip portion 13 connecting the
die-bonding portion 11 and the terminal portion 12 to each other.
The die-bonding portion 11 has an opening 11d, and the LED unit 3A
is bonded to the die-bonding portion by using a bonding material,
not shown. The opening 11d is filled with the support member 6.
[0057] The LED unit 3A has an electrode terminal 31 at an end
surface in the z direction in FIG. 8 and an electrode terminal 32
at another end surface in the z direction in FIG. 8. The electrode
terminal 31 is electrically connected to the lead 1A by its contact
with the die-bonding portion 11. The electrode terminal 32 is
connected to the wire-bonding portion 21 of the lead 2A by a wire
53.
[0058] In this embodiment, as shown in FIG. 8, the opening 11d is
formed in such a manner as to avoid the electrode terminal 31.
[0059] The LED units 3B and 3C mounted on the leads 1B and 1C have
the same structure as that of the LED unit 3 of the LED module A1.
The LED unit 3B is connected to the lead 1B via a wire 51 and
connected to the lead 2B via a wire 52. The LED unit 3C is
connected to the lead 1C via a wire 51 and connected to the lead 2C
via a wire 52.
[0060] The die-bonding portion 11 of each of the leads 1B and 1C
has an opening 11a similar to the opening provided in the LED
module A1, for example.
[0061] In this embodiment, all the terminal portions 12, 22 of the
leads 1A, 1B, 1C, 2A, 2B and 2C are exposed to the outside of the
support member 6 from the lower side in the y direction in FIG.
7.
[0062] The two Zener diodes 8 are mounted on the leads 2B and 2C,
respectively, and connected to the leads 1B and 1C via wires 54 and
55. The Zener diodes 8 prevent application of excessive reverse
voltage to the LED units 3B and 3C and allow current to flow in a
reverse direction only when an excessive reverse voltage above a
certain value is applied.
[0063] The LED module A4 also exhibits high heat dissipation
performance because the LED units 3A, 3B and 3C are mounted on the
leads 1A, 1B and 1C made of a metal. Further, the light emitted
from the LED units 3A, 3B and 3C toward one side in the z direction
is efficiently reflected toward the other side in the z direction
by the white support member 6 filling the openings 11a and 11d
formed in the leads 1A, 1B and 1C.
[0064] FIGS. 9 and 10 show an LED module according to a fifth
embodiment of the present invention. The LED module A5 of this
embodiment differs from the LED module A1 in structure of the LED
unit 3. In this embodiment, the LED unit 3 includes an LED chip 30
and a sub-mount substrate 33 supporting the LED chip.
[0065] The LED chip 30 is made by forming a layer of a
semiconductor material such as gallium nitride on a surface of a
substrate made of e.g. sapphire. The LED chip 30 emits blue light,
green light, red light or the like due to recombination of
electrons and holes in an active layer sandwiched between an n-type
semiconductor layer and a p-type semiconductor layer. In the LED
chip 30, since the light emitted is hardly absorbed by the sapphire
substrate, light is emitted in almost all directions. The LED chip
30 is provided with an electrode terminal 31 electrically connected
to the n-type semiconductor layer and an electrode terminal 32
electrically connected to the p-type semiconductor layer. As shown
in FIG. 9, the LED chip 30 is so arranged as to include the
entirety of the opening 11a, as viewed in the z direction.
[0066] The sub-mount substrate 33 is a transparent substrate made
of e.g. Si and mounted on the lead 1 by using a transparent bonding
material 4. The upper end surface in the direction z is provided
with an electrode pad 34 at one end in the x direction and an
electrode pad 35 at the other end in the x direction. As shown in
FIG. 9, the electrode pads 34 and 35 are formed so as not to
overlap the opening 11a as viewed in the z direction. The electrode
pad 34 is electrically connected to the die-bonding portion 11 via
a wire 51. The electrode pad 35 is electrically connected to the
wire-bonding portion 21 via a wire 52.
[0067] As shown in FIG. 10, the LED chip 30 is mounted on the
sub-mount substrate 33, with the electrode terminal 31 electrically
connected to the electrode pad 34 and the electrode terminal 32
electrically connected to the electrode pad 35. The electrode
terminals 31 and 32 are bonded to the electrode pads 34 and 35 by
e.g. eutectic bonding.
[0068] Since the sub-mount substrate 33 is mounted on the lead 1
made of a metal, heat generated during light emission of the LED
chip 30 is readily transmitted to the lead 1. Since the terminal
portion 12 of the lead 1 is exposed to the outside of the support
member 6, heat transferred to the lead 1 is readily released to the
outside air. Thus, the LED module A5 exhibits high heat dissipation
performance. Further, deterioration due to temperature rise of the
LED chip 30 is prevented, so that reliability is enhanced.
[0069] Moreover, according to this embodiment, part of the light
emitted from the LED chip 30 downward in the z direction passes
through the transparent sub-mount substrate 33 and is then
reflected by the white support member 6 filling the opening 11a to
travel upward in the z direction. In this way, in the LED module
A5, light traveling downward in the z direction is efficiently
turned into light traveling upward in the z direction. Thus, the
LED module A5 can utilize light from the LED chip 30 with a high
efficiency close to the efficiency provided when the LED unit 3 is
placed on a white non-metal material, while exhibiting high heat
dissipation performance by the use of the metal lead 1.
[0070] FIG. 11 shows an LED module according to a sixth embodiment
of the present invention. The LED module A6 of this embodiment
differs from the LED module A5 in the manner in which the LED unit
3 is mounted. The structures of other parts are the same as those
of the LED module A5. Further, in this embodiment, the sub-mount
substrate 33 is mounted on the lead 1 by using a conductive bonding
material 41 such as silver paste.
[0071] In this embodiment, the lower end surface of the LED chip 30
in the z direction is provided with an electrode terminal 31, which
is electrically connected to the p-type semiconductor layer, at one
end in the x direction and an electrode terminal 32, which is
electrically connected to the n-type semiconductor layer, at the
other end in the x direction.
[0072] The sub-mount substrate 33 of this embodiment has a
through-hole 33a filled with an electric conductor 36, instead of
having an electrode pad 34. The electric conductor 36 is
electrically connected to the lead 1 via the bonding material 41.
Because of this arrangement, the wire 51 is not provided in this
embodiment.
[0073] The LED chip 30 of this embodiment is mounted on the
sub-mount substrate 33, with the electrode terminal 31 electrically
connected to the electric conductor 36 and the electrode terminal
32 electrically connected to the electrode pad 35. The electrode
pad 35 and the wire-bonding portion 21 are connected to each other
via a wire 52.
[0074] As shown in FIG. 11, the bonding material 41 is formed so as
not to overlap the opening 11a.
[0075] With the LED module A6 again, part of the light emitted from
the LED chip 30 downward in the z direction passes through the
transparent sub-mount substrate 33 and is then reflected by the
white support member 6 filling the opening 11a to travel upward in
the z direction. In this way, in the LED module A6, light traveling
downward in the z direction is efficiently turned into light
traveling upward in the z direction. Thus, the LED module A6 can
utilize light from the LED chip 30 with a high efficiency close to
the efficiency provided when the LED unit 3 is placed on a white
non-metal material, while exhibiting high heat dissipation
performance by the use of the metal lead 1.
[0076] The LED module of the present invention is not limited to
the foregoing embodiments. The specific structure of each part of
the LED module according to the present invention can be varied in
design in many ways. For instance, e.g. aluminum nitride may be
added as a heat dissipating filler to the bonding material 4 of the
LED modules A1-A3. Enhancing the heat conductivity of the bonding
material 4 promotes heat transfer from the LED unit 3 to the lead
1.
[0077] Although the openings 11a, 11b, 11d are rectangular as
viewed in the z direction in the foregoing embodiments, the
openings may be circular or oval or have other polygonal shape.
[0078] Although the leads 1, 2, 1A, 1B, 1C, 2A, 2B and 2C are made
of a copper plate plated with silver, other metals may be used to
form the leads.
[0079] Although the support member 6 is made of a white resin in
the foregoing embodiments, an LED module employing a white ceramic
substrate similarly to the conventional LED module X also provides
the advantages of the present invention.
[0080] Although openings 11a are provided in the LED modules A5 and
A6, openings similar to the opening 11b of the LED module A2 or
similar to the opening 11c of the LED module A3 may be
provided.
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