U.S. patent application number 13/543418 was filed with the patent office on 2013-01-03 for led module and packaging method thereof.
This patent application is currently assigned to INDUSTRIAL TECHNOLOGY RESEARCH INSTITUTE. Invention is credited to Yi-Ping Huang, Chieh-Lung Lai, Hsiu-Jen Lin, Jian-Shian Lin, Weng-Jung Lu, Ya-Chun Tu.
Application Number | 20130005055 13/543418 |
Document ID | / |
Family ID | 42265776 |
Filed Date | 2013-01-03 |
United States Patent
Application |
20130005055 |
Kind Code |
A1 |
Lin; Jian-Shian ; et
al. |
January 3, 2013 |
LED MODULE AND PACKAGING METHOD THEREOF
Abstract
A light-emitting diode (LED) module and an LED packaging method.
As the LED module is packaged under the consideration of candela
distribution, each of the lead frames of the LED chips packaged in
the LED module is bended for tilting the LED chips by different
angles to exhibit various lighting effects. Meanwhile, in the LED
packaging method, a plurality of LED chips can be loaded on board
rapidly and aligned by one operation to result in less deviation in
the candela distribution curve.
Inventors: |
Lin; Jian-Shian; (Yilan
County, TW) ; Lai; Chieh-Lung; (Taichung County,
TW) ; Lin; Hsiu-Jen; (Taipei County, TW) ; Lu;
Weng-Jung; (Hsinchu City, TW) ; Huang; Yi-Ping;
(Taoyuan County, TW) ; Tu; Ya-Chun; (Taipei
County, TW) |
Assignee: |
INDUSTRIAL TECHNOLOGY RESEARCH
INSTITUTE
Hsinchu
TW
|
Family ID: |
42265776 |
Appl. No.: |
13/543418 |
Filed: |
July 6, 2012 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12634468 |
Dec 9, 2009 |
8235551 |
|
|
13543418 |
|
|
|
|
Current U.S.
Class: |
438/15 ;
257/E33.059 |
Current CPC
Class: |
F21Y 2115/10 20160801;
H01L 25/0753 20130101; H01L 2224/45147 20130101; H01L 2224/48247
20130101; H01L 2224/45144 20130101; H01L 2224/45124 20130101; F21V
19/02 20130101; H01L 2224/45144 20130101; H01L 2224/48091 20130101;
H01L 2224/45147 20130101; H01L 2224/48091 20130101; H01L 2924/01322
20130101; H01L 2924/01047 20130101; H01L 2224/45124 20130101; H01L
2224/29339 20130101; F21Y 2107/50 20160801; H01L 2924/01047
20130101; H01L 2924/01014 20130101; H01L 2924/01322 20130101; H01L
2924/00014 20130101; H01L 2924/00 20130101; H01L 2924/00 20130101;
H01L 2924/00014 20130101; F21K 9/00 20130101; H01L 2924/00014
20130101; H01L 33/62 20130101 |
Class at
Publication: |
438/15 ;
257/E33.059 |
International
Class: |
H01L 33/62 20100101
H01L033/62 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 24, 2008 |
TW |
097150385 |
Jan 6, 2009 |
TW |
098100152 |
Jan 15, 2009 |
TW |
098101324 |
Sep 29, 2009 |
TW |
098132874 |
Claims
1-6. (canceled)
7. An LED packaging method, comprising steps of: forming a bonding
metal material or metal colloidal particles on a lead frame;
placing an LED chip on the bonding metal material or the metal
colloidal particles; heating up the lead frame so that the LED chip
is bonded with the lead frame by the bonding metal material or the
metal colloidal particles; performing an interconnect bonding
process on the LED chip; bending the lead frame by a predetermined
angle according to a candela distribution curve to construct a
tilted plane; performing an encapsulation process and a baking
process on the bended lead frame and the LED chip to form a
three-dimensional LED module; and performing a testing process on
the three-dimensional LED module.
8. The LED packaging method as recited in claim 7, wherein the lead
frame is bended by the predetermined angle with the use of a
mold.
9. The LED packaging method as recited in claim 7, wherein the
tilted plane is recessed to form a cup having a reflective
surface.
10. The LED packaging method as recited in claim 7, wherein a cup
having a reflective surface protrudes from the tilted plane.
11. The LED packaging method as recited in claim 7, wherein the
back of the LED chip and the lead frame are coated by a
metalization layer formed by Ti/Ni/Au, Al/Ni/Au, Cr/Ni/Au or
combination thereof before the LED chip is bonded with the lead
frame.
12. The LED packaging method as recited in claim 11, wherein the
bonding metal or the metal colloidal particles are reacted with the
metalization layer when the lead frame is heated up.
13. The LED packaging method as recited in claim 7, wherein the
interconnect bonding process is performed by flip-chip bonding or
wire bonding.
14. The LED packaging method as recited in claim 7, further
comprising a step of performing an initial encapsulation process
and an initial baking process after the interconnect bonding
process.
15-20. (canceled)
21. An LED packaging method, comprising steps of: forming a bonding
metal material or metal colloidal particles on a lead frame;
placing a LED chip on the bonding metal material or the metal
colloidal particles; heating up the lead frame so that the LED chip
is bonded with the lead frame by the bonding metal material or the
metal colloidal particles; performing an interconnect bonding
process on the LED chip; aligning and bonding the lead frame and
the substrate; performing an encapsulation process and a baking
process on the lead frame and the substrate to form an LED module;
and performing a testing process on the LED module.
22. The LED packaging method as recited in claim 21, further
comprising a step of removing a framework of the lead frame after
the lead frame and the substrate are aligned and bonded.
23. The LED packaging method as recited in claim 21, wherein the
lead frame is bended by a predetermined angle according to a
candela distribution curve to construct a tilted plane after the
interconnect bonding process.
24. The LED packaging method as recited in claim 23, further
comprising a step of performing an initial encapsulation process
and an initial baking process before the lead frame is bended.
25. The LED packaging method as recited in claim 21, wherein the
lead frame is bended by the predetermined angle with the use of a
mold.
26. The LED packaging method as recited in claim 23, wherein the
tilted plane is recessed to form a cup having a reflective
surface.
27. The LED packaging method as recited in claim 23, wherein a cup
having a reflective surface protrudes from the tilted plane.
28. The LED packaging method as recited in claim 21, wherein the
back of the LED chip and the lead frame are coated by a
metalization layer formed by Ti/Ni/Au, Al/Ni/Au, Cr/Ni/Au or
combination thereof before the LED chip is bonded with the lead
frame.
29. The LED packaging method as recited in claim 28, wherein the
bonding metal or the metal colloidal particles are reacted with the
metalization layer when the lead frame is heated up.
30. The LED packaging method as recited in claim 21, wherein the
interconnect bonding process is performed by flip-chip bonding or
wire bonding.
Description
TECHNICAL FIELD
[0001] The disclosure generally relates to an LED module and a
packaging method thereof and, more particularly, to an LED module
and an LED packaging method, wherein the LED module is packaged
under the consideration of candela distribution and each of the
lead frames of the LED chips packaged in the LED module is bended
for tilting the LED chips by different angles to exhibit various
lighting effects without using additional light control elements.
Meanwhile, in the LED packaging method, a plurality of LED chips
can be loaded on board rapidly and aligned by one operation to
result in less deviation in the candela distribution curve.
TECHNICAL BACKGROUND
[0002] In the field of lighting, light-emitting diodes (LED's) are
becoming more and more popular because they are advantages as being
compact, high-efficiency, durable and diverse in colors. Unlike
conventional lighting elements, an LED lamp generally comprises a
plurality of LED ships arranged in an array because a single LED
ship is small and emits light of relatively insufficient intensity.
Moreover, the light from an LED is directional. In an LED lamp, the
LED chips are usually arranged inclined or are provided with light
control elements to meet the requirements of a candela distribution
curve. However, it costs higher when the LED chips are arranged
inclined because additional molds are required and the assembly
cost rises, which leads to higher cost and lower popularity of the
LED lamp. Moreover, the use of light control elements reduces the
light-emitting efficiency, which can be compensated by increased
numbers of LED chips with more electricity consumed and higher lamp
cost.
[0003] Conventionally, to meet the requirements of a candela
distribution curve, the LED lamp uses light control elements such
as light control lenses, geometrical reflecting screen s and LED
devices that are arranged to correct the candela distribution curve
of the LED lamp.
[0004] U.S. Pat. Pub. No. 2006/0232976 discloses a lighting device
with an integration sheet as shown in FIG. 1. The lighting device
comprises a light source 21 and at least a sheet 22. The light
source 21 comprises a luminous body 211 and a reflecting screen
212. The sheet 22 is disposed at the light-emitting end of the
light source 21. The sheet 22 comprises a plurality of light
diffusion zones 221, 222, 223. Each of the light diffusion zones
221, 222, 223 has a plural arrays of microstructures arranged on
the surface thereof and each array of microstructures is capable of
changing the diopter of the corresponding light diffusion zone. By
controlling the distribution of the plural arrays of
microstructures, the Gaussian distribution of the light source 21
can be improved while collimating the scattered light beams to the
intended illuminating area 9 of the lighting device and diffusing
the light beams emitting from the center of the light source 21 to
the same so that not only the luminous efficacy of the lighting
device is enhanced, but also the uniformity of the illuminance of
the lighting device is improved.
[0005] U.S. Pat. Pub. No. 2006/0139933 discloses a reflector with
negative focal length as shown in FIG. 2. The top of the luminaire
screen 20 is a reflector of single negative focal length 51, such
that the cross section of the luminaire screen 20 is a concavity
with a side screen 52 connecting to the edge of the reflector 51.
By the luminaire screen 20 of FIG. 2, the upward-incident rays
emitting from a light source 53 are first reflected to the side
screen 52 by the reflector 51, and then are further reflected such
that a plurality of discharging rays 54 are generated. It is noted
that the discharging rays 54 are discharge out of the luminaire by
large angles for reducing glare. In addition, the height of the
luminaire can be reduced.
[0006] U.S. Pat. No. 5,838,247 discloses a solid state light system
as shown in FIG. 3. In FIG. 3, a lamp 40 has a plurality of
inclined lamps 12 with a reflector 44 inclined at a complementary
angle A, so as to direct the light parallel to the polar axis 36 of
lamp 40. The angle of convergence or divergence may vary, with the
angle of the reflector correspondingly selected to achieve the
desired direction and type of light output.
SUMMARY
[0007] In view of the above, this disclosure provides an LED module
and an LED packaging method, wherein the LED module is packaged
under the consideration of candela distribution and thus each of
the lead frames of the LED chips packaged in the LED module is
bended for tilting the LED chips by different angles to exhibit
various lighting effects without using additional light control
elements.
[0008] In one embodiment, this disclosure provides an LED module,
comprising: a plurality of lead frames, each being bended by a
predetermined angle according to a candela distribution curve to
construct a tilted plane; and a plurality of LED chips, each being
fixedly disposed on the tilted plane constructed by each of the
lead frames.
[0009] In another embodiment, this disclosure provides an LED
packaging method, comprising steps of: forming a bonding metal
material or metal colloidal particles on a lead frame; placing a
LED chip on the bonding metal material or the metal colloidal
particles; heating up the lead frame so that the LED chip is bonded
with the lead frame by the bonding metal material or the metal
colloidal particles; performing an interconnect bonding process on
the LED chip; bending the lead frame by a predetermined angle
according to a candela distribution curve to construct a tilted
plane; performing an encapsulation process and a baking process on
the bended lead frame and the LED chip to form a three-dimensional
LED module; and performing a testing process on the
three-dimensional LED module.
[0010] In another embodiment, this disclosure provides an LED
module, comprising: a plurality of lead frames, being bendable; and
a plurality of LED chips, each being fixedly disposed on the lead
frames; and a substrate, being disposed under and electrically
coupled to the lead frames.
[0011] In another embodiment, this disclosure provides an LED
packaging method, comprising steps of: forming a bonding metal
material or metal colloidal particles on a lead frame; placing an
LED chip on the bonding metal material or the metal colloidal
particles; heating up the lead frame so that the LED chip is bonded
with the lead frame by the bonding metal material or the metal
colloidal particles; performing an interconnect bonding process on
the LED chip; aligning and bonding the lead frame and the
substrate; performing an encapsulation process and a baking process
on the lead frame and the substrate to form an LED module; and
performing a testing process on the LED module.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The embodiments of the disclosure will be readily understood
by the accompanying drawings and detailed descriptions,
wherein:
[0013] FIG. 1 is a structural diagram of a conventional lighting
device with an integration sheet in U.S. Pat. Pub. No.
2006/0232976;
[0014] FIG. 2 is a structural diagram of a conventional reflector
with negative focal length in U.S. Pat. Pub. No. 2006/0139933;
[0015] FIG. 3 is a structural diagram of a conventional lamp of a
solid state light system in U.S. Pat. No. 5,838,247;
[0016] FIG. 4 is a cross-sectional diagram of a packaging structure
for an LED module according to a first embodiment of the
disclosure;
[0017] FIG. 5A is a cross-sectional diagram of a packaging
structure for an LED module according to a second embodiment of the
disclosure;
[0018] FIG. 5B is a cross-sectional diagram of a packaging
structure for an LED module according to a third embodiment of the
disclosure;
[0019] FIG. 5C is a three-dimensional diagram of a packaging
structure for an LED module according to a fourth embodiment of the
disclosure;
[0020] FIG. 6 is a flowchart of a LED packaging method according to
a first embodiment of the disclosure;
[0021] FIG. 7 is a cross-sectional diagram of a packaging structure
for an LED module with a bended lead frame using a mold according
to the disclosure;
[0022] FIG. 8 is a three-dimensional diagram of a packaging
structure for an LED module according to the disclosure;
[0023] FIG. 9A to FIG. 9C are cross-sectional diagrams showing
packaging steps of an LED module according to a fifth embodiment of
the disclosure;
[0024] FIG. 10A to FIG. 10C are cross-sectional diagrams showing
packaging steps of an LED module according to a sixth embodiment of
the disclosure;
[0025] FIG. 11A to FIG. 11C are cross-sectional diagrams showing
packaging steps of an LED module according to a seventh embodiment
of the disclosure;
[0026] FIG. 12A is a graph showing a distribution of light emitted
from an LED module (FIG. 5C) according to a fourth embodiment of
the disclosure;
[0027] FIG. 12B is a graph showing a distribution of illumination
of an LED module (FIG. 5C) according to a fourth embodiment of the
disclosure;
[0028] FIG. 13A is a graph showing a distribution of light emitted
from an LED module (FIG. 10A to FIG. 10C) according to a sixth
embodiment of the disclosure;
[0029] FIG. 13B is a graph showing a distribution of illumination
of an LED module (FIG. 10A to FIG. 10C) according to a sixth
embodiment of the disclosure;
[0030] FIG. 14A is a graph showing a distribution of light emitted
from an LED module (FIG. 11A to FIG. 11C) according to a seventh
embodiment of the disclosure;
[0031] FIG. 14B is a graph showing a distribution of illumination
of an LED module (FIG. 11A to FIG. 11C) according to a seventh
embodiment of the disclosure;
[0032] FIG. 15 is a flowchart of a LED packaging method according
to a fifth embodiment (FIG. 9A to FIG. 9C) of the disclosure;
and
[0033] FIG. 16 is a flowchart of a LED packaging method according
to a sixth embodiment (FIG. 11A to FIG. 11C) of the disclosure.
DETAILED DESCRIPTION OF EMBODIMENTS
[0034] The disclosure can be exemplified by but not limited to
various embodiments as described hereinafter.
[0035] Please refer to FIG. 4, which is a cross-sectional diagram
of a packaging structure for an LED module according to a first
embodiment of the disclosure. The LED module 1 comprises a
plurality of lead frames 11, each being bended by a predetermined
angle according to a candela distribution curve to construct a
tilted plane 112; and a plurality of LED chips 12, each being
fixedly disposed on the tilted plane 112 constructed by each of the
lead frames 11. The lead frames 11 comprise Cu, Fe, Ni or
combination thereof. The LED chips 12 comprise semiconductor
materials such as GaN, GaInN, AlInGaP, AlInGaN, AlN, InN, GaInAsN
and GaInPN. The LED chips 12 are sapphire-based, thin-GaN LED's or
flip-chip packaged. Moreover, each of the lead frames 11 is
provided with a heat sink 14 at the bottom. The lead frames 11, LED
chips 12 and the heat sink 14 are further covered by a transparent
encapsulant 13.
[0036] Please refer to FIG. 5A, which is a cross-sectional diagram
of a packaging structure for an LED module according to a second
embodiment of the disclosure. FIG. 5A is different from FIG. 4 in
that the tilted plane 112 is recessed to form a cup 111 having a
reflective surface so that the light from the LED chip 12 is more
uniform than in FIG. 4.
[0037] FIG. 5B is a cross-sectional diagram of a packaging
structure for an LED module according to a third embodiment of the
disclosure; and FIG. 5C is a three-dimensional diagram of a
packaging structure for an LED module according to a fourth
embodiment of the disclosure. In FIG. 5B and FIG. 5C, a cup 113
having a reflective surface protrudes from the tilted plane 112 so
that the light from the LED chip 12 is more uniform. The cup 113
can be formed by injection molding.
[0038] Please refer to FIG. 6, which is a flowchart of a LED
packaging method according to a first embodiment of the disclosure.
Meanwhile, please refer to FIG. 7 for a cross-sectional diagram of
a packaging structure for an LED module with a bended lead frame
using a mold 15 according to the disclosure. The flowchart in FIG.
6 comprises steps herein:
[0039] In Step 21, a bonding metal material or metal colloidal
particles are formed on a lead frame. The bonding metal material
comprises single elements or alloys, such as Sn, Au, Au--Sn,
Sn--Pb, Sn--Ag--Cu, Sn--Zn, Sn--Cu, Sn--Bi, In--Sn or combination
thereof. The metal colloidal particles comprise a mixture of metal
particles and polymer colloids, such as a silver paste, a copper
paste or combination thereof formed by electroplating, screen
printing, evaporation, sputtering or coating.
[0040] In Step 22, a LED chip is placed on the bonding metal
material or the metal colloidal particles. To facilitate bonding,
the back of the LED chip and the lead frame are coated by a
metalization layer formed by Ti/Ni/Au, Al/Ni/Au, Cr/Ni/Au or
combination thereof before the LED chip is bonded with the lead
frame.
[0041] In Step 23, the lead frame is heated up so that the LED chip
is bonded with the lead frame by the bonding metal material or the
metal colloidal particles. The bonding metal or the metal colloidal
particles are reacted with the metalization layer when the lead
frame is heated up.
[0042] In Step 24, an interconnect bonding process is performed on
the LED chip by flip-chip bonding or wire bonding. Flip-chip joints
in flip-chip bonding comprise single elements or alloys such as Sn,
Au, Au--Sn, Sn--Pb, Sn--Ag--Cu, Sn--Zn, Sn--Cu, Sn--Bi, In--Sn or
combination thereof formed by electroplating, screen printing,
evaporation, sputtering or coating. Metal leads in wire bonding
comprise single metal elements or alloys such as Au, Al, Cu,
Al--Si, Cu--Ag or combination thereof formed using hot-pressing,
ultrasonic or hot-pressing ultrasonic.
[0043] In Step 25, an initial encapsulation process and an initial
baking process are performed to prevent the LED chip and wiring
from being bended before the lead frame is bended. In the initial
encapsulation process, a transparent encapsulant is formed of epoxy
or silicone in the initial encapsulation process. It is noted that,
this step is optional so as to prevent the LED chip and wiring from
being bended before the lead frame is bended.
[0044] In Step 26, the lead frame is bended by a predetermined
angle according to a candela distribution curve to construct a
tilted plane with the use of a mold.
[0045] In Step 27, an encapsulation process and a baking process
are performed on the bended lead frame and the LED chip to form a
three-dimensional LED module.
[0046] In Step 28, a testing process is performed on the
three-dimensional LED module.
[0047] In view of the above, the LED packaging method of this
disclosure is different from the conventional planar LED in that
the lead frame is bended by a predetermined angle according to the
candela distribution curve in Step 26. Therefore, the lighting
orientation is determined by the predetermined angle to meet the
requirements of a candela distribution curve without using any
optical component.
[0048] Please refer to FIG. 8, which is a three-dimensional diagram
of a packaging structure for an LED module according to the
disclosure. In FIG. 8, the lead frame 31 is provided with a
plurality of carriers 312a-312d. Each of the carriers 312a-312d is
provided with a pin 311. Each of the carriers 312a-312d is extended
from the lead frame 31 and is coupled thereto. The pin 311 is
separated from the lead frame 31 and the carriers 312a-312d. Each
of the carriers 312a-312d is provided with an LED chip 32, which is
electrically coupled to the pin 311 by way of a wire 34 formed by a
wire bonding process (i.e., the interconnect bonding process in
Step 24 in FIG. 6). Therefore, an LED module is formed by covering
the lead frame 31, the pin 311, the carriers 312a-312d, the LED
chip 32 and the wire 34 with a transparent encapsulant 33. It is
understood that, in the present embodiment, the LED packaging
method achieves reducing the size of the LED lamp, manufacturing
cost and improving the light-emitting efficiency. Moreover, in FIG.
8, it is to be determined whether the carriers 312a-312d are bended
or not or how the carriers 312a-312d are bended according to
practical use. In the present embodiment, the carrier 312a in FIG.
8 is not bended, while the carrier 312b is most inclinedly bended.
The carriers 312b-312d are equivalent to the tilted planes 112 in
FIG. 4, FIG. 5A and FIG. 5B, respectively. In addition to the
carriers 312a-312d in FIG. 8, descriptions of other carriers are
not presented though they are bended by different angles.
[0049] Even though the LED modules in FIG. 4, FIG. 5A to FIG. 5C
and FIG. 8 are differently structured, they have things in common.
For example, the carriers for carrying the LED chips, such as the
tilted planes 112 in FIG. 4, FIG. 5A to FIG. 5C, and the carriers
312a-312d in FIG. 8, can be bended by an angle according to a
candela distribution curve. In other words, the carriers can be
disposed as a horizontal plane or bended by different angles.
Moreover, when the LED modules are structured differently, the LED
chips are bonded differently. For example, in FIG. 8, the LED chips
32 are bonded by way of wires 34 to be electrically coupled to the
pins 311. Alternatively, the LED chips can be electrically coupled
to the pin as described herein.
[0050] Referring to FIG. 9A to FIG. 9C, the lead frame 41 is viewed
along the A-A line of the LED module in FIG. 8. In FIG. 9A, the
carriers 412a-412d are not bended. An LED chip 42 is attached on
each of the carriers 412a-412d by a silver paste, a solder or
eutectic die attachment and is coupled to the joints (not shown) on
the carriers 412a-412d by a wire 44 formed by wire bonding.
Referring to FIG. 9B, the substrate 45 is provided with solder
joints 451 thereon. The substrate 45 may comprise copper, aluminum
or ceramic or be a printed circuit board. The solder joints 451 can
be formed of a solder paste 451 by screen printing or a solder by
electroplating. The lead frame 41 with the LED chip 42 and the wire
44 is further aligned with the substrate 45 and is heated up so
that the lead frame 41 and the substrate 45 are bonded. The solder
paste may be lead-free or lead-containing The solder paste may be
heated up by hot blast, infrared heating and hot plate heating. The
framework of the lead frame 41 can be removed using a knife mold.
The packaging structure in FIG. 9B undergoes an encapsulation
process and a baking process to form an encapsulant 43 comprising
epoxy or silicone. An LED module 4 can be packaged as shown in FIG.
9C. Since the carriers 412a-412d are not bended, the light 421 from
the LED chips 42 is oriented the same. It is noted that the present
embodiment only demonstrates a cross-sectional view of the lead
frames. However, a 4.times.4 array of LED chips can be attached
onto the lead frame as shown in FIG. 8. Similarly, a 5.times.5 or
6.times.6 array of LED chips can be used.
[0051] Accordingly, in this disclosure, a plurality of LED chips
can be attached onto the lead frame and the alignment positions are
determined during manufacturing. Therefore, the LED chips can be
loaded on board rapidly and aligned by one operation to result in
less deviation in the candela distribution curve. Moreover, the LED
chips can be disposed inclinedly with adjustable angles. Therefore,
a three-dimensional LED module can be formed according to this
disclosure. Please refer to FIG. 10A to FIG. 10C and FIG. 11A to
FIG. 11C for alternative embodiments.
[0052] Referring to FIG. 10A to FIG. 10C, the lead frame 51 is
provided with a plurality of carriers 512a-512d. Each of the
carriers 512a-512d is provided with an LED chip 52, which is
electrically coupled to joints (not shown) on the carriers
512a-512d by way of a wire 54 to construct a multi-chip lead frame
as shown in FIG. 10A. The present embodiment is characterized in
that the carriers 512a-512d are bended by a predetermined angle
.theta.. Referring to FIG. 10B, solder joints 551 are formed on the
substrate 55 to align the lead frame 51 (being provided with the
LED chips 52 and the wire 54) with the substrate 55 so that the
lead frame 51 and the substrate 55 are bonded after being heated
up. The packaging structure in FIG. 10B undergoes an encapsulation
process and a baking process to form an encapsulant 53. An LED
module 5 can be packaged as shown in FIG. 10C.
[0053] Referring to FIG. 11A to FIG. 11C, the lead frame 61 is
provided with a plurality of carriers 612a-612d Each of the
carriers 612a-612d is provided with an LED chip 62, which is
electrically coupled to joints (not shown) on the carriers
612a-612d by way of a wire 64 to construct a multi-chip lead frame
as shown in FIG. 11A. The present embodiment is characterized in
that the outer carriers 612a, 612d are bended by a predetermined
angle .theta., while the inner carriers 612b, 612c are not bended.
Referring to FIG. 11B, solder joints 651 are formed on the
substrate 65 to align the lead frame 61 (being provided with the
LED chips 62 and the wire 64) with the substrate 65 so that the
lead frame 61 and the substrate 65 are bonded after being heated
up. The packaging structure in FIG. 11B undergoes an encapsulation
process and a baking process to form an encapsulant 63. A
multi-chip LED module 6 can be packaged as shown in FIG. 11C. Since
the outer carriers 612a, 612d are inclined outwards by an angle
.theta., the light 621 from the LED module 6 exhibits a wider
light-emitting range.
[0054] Accordingly, this disclosure provides various embodiments as
described herein.
[0055] In FIG. 4, the lead frame is bended by at least two
different angles and is provided with a heat sink at the
bottom.
[0056] In FIG. 5A, the lead frame is bended to be recessed with
cups inclined by at least two different angles and is provided with
a heat sink at the bottom.
[0057] In FIG. 5B, the lead frame is bended to form protruding cups
inclined by at least two different angles.
[0058] In FIG. 5C, the lead frame is not bended and is provided
with cups.
[0059] In FIG. 9A, the lead frame is not bended and is planar.
[0060] In FIG. 10A, the lead frame is bended by the same angle.
[0061] In FIG. 8 and FIG. 11A, the lead frame is partially bended
and partially unbended.
[0062] FIG. 12A is a graph showing a distribution of light emitted
from an LED module (FIG. 5C) according to a fourth embodiment of
the disclosure. The light distribution is narrow and the
distribution of illumination is as shown in FIG. 12B. Moreover,
FIG. 13A is a graph showing a distribution of light emitted from an
LED module (FIG. 10A to FIG. 10C) according to a sixth embodiment
of the disclosure. Compared to FIG. 12A, the light distribution in
FIG. 13A is inclined and the distribution of illumination is as
shown in FIG. 13B. FIG. 14A is a graph showing a distribution of
light emitted from an LED module (FIG. 11A to FIG. 11C) according
to a seventh embodiment of the disclosure. Compared to FIG. 12A,
the light distribution in FIG. 14A is wider and the distribution of
illumination is as shown in FIG. 14B.
[0063] FIG. 15 is a flowchart of a LED packaging method according
to a fifth embodiment (FIG. 9A to FIG. 9C) of the disclosure. The
flowchart in FIG. 15 comprises steps herein:
[0064] In Step 71, a bonding metal material or metal colloidal
particles are formed on a lead frame. The bonding metal material
comprises single elements or alloys, such as Sn, Au, Au--Sn,
Sn--Pb, Sn--Ag--Cu, Sn--Zn, Sn--Cu, Sn--Bi, In--Sn or combination
thereof. The metal colloidal particles comprise a mixture of metal
particles and polymer colloids, such as a silver paste, a copper
paste or combination thereof formed by electroplating, screen
printing, evaporation, sputtering or coating.
[0065] In Step 72, a LED chip is placed on the bonding metal
material or the metal colloidal particles. To facilitate bonding,
the back of the LED chip and the lead frame are coated by a
metalization layer formed by Ti/Ni/Au, Al/Ni/Au, Cr/Ni/Au or
combination thereof before the LED chip is bonded with the lead
frame.
[0066] In Step 73, the lead frame is heated up so that the LED chip
is bonded with the lead frame by the bonding metal material or the
metal colloidal particles. The bonding metal or the metal colloidal
particles are reacted with the metalization layer when the lead
frame is heated up.
[0067] In Step 74, an interconnect bonding process is performed on
the LED chip by flip-chip bonding or wire bonding. Flip-chip joints
in flip-chip bonding comprise single elements or alloys such as Sn,
Au, Au--Sn, Sn--Pb, Sn--Ag--Cu, Sn--Zn, Sn--Cu, Sn--Bi, In--Sn or
combination thereof formed by electroplating, screen printing,
evaporation, sputtering or coating. Metal leads in wire bonding
comprise single metal elements or alloys such as Au, Al, Cu,
Al--Si, Cu--Ag or combination thereof formed using hot-pressing,
ultrasonic or hot-pressing ultrasonic.
[0068] In Step 75, the lead frame and the substrate aligned and
bonded after the die attachment process, the wire bonding
process.
[0069] In Step 76, an encapsulation process and a baking process
are performed on the lead frame and the substrate to form an LED
module. A stamping machine is used to form a transparent
encapsulant in the initial encapsulation process.
[0070] In Step 77, a testing process is performed on the LED
module.
[0071] The flowchart in FIG. 15 further comprises a step 751 of
removing a framework of the lead frame after Step 75. More
particular, the framework can be removed by a knife mold.
[0072] The above Step 71 and Step 77 are performed on unbended lead
frame as shown in FIG. 9A. For lead frames that need to be bended
as shown in FIG. 4, FIG. 5A, FIG. 5B, FIG. 7, FIG. 8, FIG. 10A,
FIG. 11A, a step of bending is required, as shown in the flowchart
in FIG. 16.
[0073] In Step 81, a bonding metal material or metal colloidal
particles are formed on a lead frame. The bonding metal material
comprises single elements or alloys, such as Sn, Au, Au--Sn,
Sn--Pb, Sn--Ag--Cu, Sn--Zn, Sn--Cu, Sn--Bi, In--Sn or combination
thereof. The metal colloidal particles comprise a mixture of metal
particles and polymer colloids, such as a silver paste, a copper
paste or combination thereof formed by electroplating, screen
printing, evaporation, sputtering or coating.
[0074] In Step 82, an LED chip is placed on the bonding metal
material or the metal colloidal particles. To facilitate bonding,
the back of the LED chip and the lead frame are coated by a
metalization layer formed by Ti/Ni/Au, Al/Ni/Au, Cr/Ni/Au or
combination thereof before the LED chip is bonded with the lead
frame.
[0075] In Step 83, the lead frame is heated up so that the LED chip
is bonded with the lead frame by the bonding metal material or the
metal colloidal particles. The bonding metal or the metal colloidal
particles are reacted with the metalization layer when the lead
frame is heated up.
[0076] In Step 84, an interconnect bonding process is performed on
the LED chip by flip-chip bonding or wire bonding. Flip-chip joints
in flip-chip bonding comprise single elements or alloys such as Sn,
Au, Au--Sn, Sn--Pb, Sn--Ag--Cu, Sn--Zn, Sn--Cu, Sn--Bi, In--Sn or
combination thereof formed by electroplating, screen printing,
evaporation, sputtering or coating. Metal leads in wire bonding
comprise single metal elements or alloys such as Au, Al, Cu,
Al--Si, Cu--Ag or combination thereof formed using hot-pressing,
ultrasonic or hot-pressing ultrasonic.
[0077] In Step 85, the lead frame is bended by a predetermined
angle according to a candela distribution curve to construct a
tilted plane by bending lead frame by a predetermined angle with
the use of a mold.
[0078] In Step 86, the lead frame and the substrate aligned and
bonded after the die attachment process, the wire bonding
process.
[0079] In Step 87, an encapsulation process and a baking process
are performed on the lead frame and the substrate to form a
three-dimensional LED module. A stamping machine is used to form a
transparent encapsulant in the initial encapsulation process.
[0080] In Step 88, a testing process is performed on the
three-dimensional LED module.
[0081] Similarly, the flowchart in FIG. 16 further comprises a step
861 of removing a framework of the lead frame after Step 86. More
particular, the framework can be removed by a knife mold.
[0082] Moreover, to prevent the LED chip and wiring from being
bended before the lead frame is bended, an initial encapsulation
process and an initial baking process are performed in Step 841. In
the initial encapsulation process, a transparent encapsulant is
formed of epoxy or silicone in the initial encapsulation process.
With Step 841, Step 87 performs a second encapsulation process and
a second baking process.
[0083] Accordingly, this disclosure can be widely applied. By the
use of an array of tilted planes on the lead frame, the light
distribution can be oriented towards a direction or inwards or
outwards to exhibit various light distributions over different
ranges. Compared to conventional LED modules, the LED module in
this disclosure exhibits higher performances with more
flexibility.
[0084] In view of FIG. 4 to FIG. 16, it is readily understood that
the disclosure relates to a light-emitting diode (LED) module and
an LED packaging method. As the LED module is packaged under the
consideration of candela distribution, each of the lead frames of
the LED chips packaged in the LED module is bended for tilting the
LED chips by different angles to exhibit various lighting effects
without using additional light control elements. Meanwhile, in the
LED packaging method, a plurality of LED chips can be loaded on
board rapidly and aligned by one operation to result in less
deviation in the candela distribution curve.
[0085] Although this disclosure has been disclosed and illustrated
with reference to particular embodiments, the principles involved
are susceptible for use in numerous other embodiments that will be
apparent to persons skilled in the art. This disclosure is,
therefore, to be limited only as indicated by the scope of the
appended claims.
* * * * *