U.S. patent application number 12/265014 was filed with the patent office on 2009-02-26 for semiconductor light emitting device.
Invention is credited to Hideo Nagai, Kunihiko Obara, Mineo Tokunaga.
Application Number | 20090053841 12/265014 |
Document ID | / |
Family ID | 35783621 |
Filed Date | 2009-02-26 |
United States Patent
Application |
20090053841 |
Kind Code |
A1 |
Obara; Kunihiko ; et
al. |
February 26, 2009 |
SEMICONDUCTOR LIGHT EMITTING DEVICE
Abstract
A semiconductor light emitting device comprises an element that
emits light and a substrate on a main surface of which the element
is mounted. The main surface of the substrate composed of two
areas, (i) a mount area which is rectangle and on which the element
is mounted, and (ii) a pad area that is equipped with a pad for
wire bonding. The pad area is contiguous to the mount area on one
side of the mount area, and the pad area decreases in width
continuously or stepwise in a direction away from the one side.
Inventors: |
Obara; Kunihiko; (Kagoshima,
JP) ; Tokunaga; Mineo; (Kagoshima, JP) ;
Nagai; Hideo; (Osaka, JP) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK L.L.P.
2033 K. STREET, NW, SUITE 800
WASHINGTON
DC
20006
US
|
Family ID: |
35783621 |
Appl. No.: |
12/265014 |
Filed: |
November 5, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10571598 |
Mar 10, 2006 |
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PCT/JP2004/014122 |
Sep 21, 2004 |
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12265014 |
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Current U.S.
Class: |
438/28 ;
257/E33.056 |
Current CPC
Class: |
H01L 2924/00 20130101;
H01L 33/62 20130101; H01L 2924/0002 20130101; H01L 2924/0002
20130101; H01L 25/167 20130101 |
Class at
Publication: |
438/28 ;
257/E33.056 |
International
Class: |
H01L 21/50 20060101
H01L021/50 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 19, 2003 |
JP |
2003-327808 |
Claims
1-9. (canceled)
10. A method for manufacturing a plurality of semiconductor light
emitting devices, each of the semiconductor light emitting devices
including an element that emits light; and a substrate on a main
surface of which the element is mounted, wherein the main surface
has (i) a mount area which is a rectangle and on which the element
is mounted, and has (ii) a pad area that has a pad for wire
bonding, wherein the pad area is contiguous to the mount area on
one side of the mount area, and the pad area decreases in width
continuously or stepwise in a direction away from the one side,
said method comprising: an array substrate generating step for
generating an array substrate in which substrates are arranged in a
unique arrangement pattern; a die bonding step for bonding elements
respectively on the substrates arranged in the array substrate, by
die bonding; and a cutting step for cutting the array substrate
into individual semiconductor light emitting devices by dicing,
wherein in the arrangement pattern, a side of the mount area that
is opposite to the one side is adjoined by a side of another mount
area for another element, with two elements on the mount area and
said another mount area adjoining back to back.
11. The method of claim 10 further including: an applying step,
between the die bonding step and the cutting step, for applying the
phosphor to the elements in a unique application pattern, wherein
in the application pattern, the phosphor is applied collectively to
the two elements that are adjoining back to back centering on the
adjoining sides.
12. The method of claim 10, wherein in the die bonding step, an
electrode that is included in the element and is connected to the
pad is positioned substantially in a center of one of two sides of
the mount area that are connected to the one side, and such that
all of the elements face the same direction.
13. A method for manufacturing a plurality of semiconductor light
emitting devices, each of the semiconductor light emitting devices
including an element that emits light; and a substrate on a main
surface of which the element is mounted, wherein the main surface
has (i) a mount area which is a rectangle and on which the element
is mounted, and has (ii) a pad area that has a pad for wire
bonding, wherein the pad area is contiguous to the mount area on
one side of the mount area, and the pad area decreases in width
continuously or stepwise in a direction away from the one side,
said method comprising: an array substrate generating step for
generating an array substrate in which substrates are arranged in a
unique arrangement pattern; a mount step for mounting elements
respectively on the substrates arranged in the array substrate; and
a cutting step for cutting the array substrate into individual
semiconductor light emitting devices by dicing, wherein in the
arrangement pattern, (i) even number rows in which substrates that
each have a mount area on the left and a pad area on the right are
connected with each other in a left-right direction and (ii) odd
number rows in which substrates that each have a mount area on the
right and a pad area on the left are connected with each other in a
left-right direction, are aligned alternately.
14. The method of claim 13 further includes: an applying step,
between the die bonding step and the cutting step, for applying the
phosphor to the elements in a unique application pattern, wherein
in the arrangement pattern, there are margins between two elements
in each pair adjoining in a row direction, and in the application
pattern, deviation of an application width is controlled by the
margins.
15. The method of claim 13, wherein in the die bonding step, an
electrode that is included in the element and is connected to the
pad is positioned substantially in a center of one of two sides of
the mount area that are connected to the one side, and such that
all of the elements face the same direction.
Description
TECHNICAL FIELD
[0001] The present invention relates to a semiconductor light
emitting device in which a flip chip semiconductor light emitting
element is mounted on a submount substrate, and particularly to a
technique for setting a semiconductor light emitting device in a
smaller space than the conventional ones.
BACKGROUND ART
[0002] In recent years, with an improvement of a technique of
semiconductors, semiconductor light emitting devices that output
white light to be equipped in lighting apparatuses have become
widely used.
[0003] Especially, semiconductor light emitting devices are compact
and require low electric power. Therefore, semiconductor light
emitting devices are suitable for installing in portable devices
such as cellular-phones and cameras, and should explosively prevail
in the near future.
[0004] A semiconductor light emitting device comprises: a
semiconductor light emitting element that emits blue light; and
translucent resin scatteredly including luminescent substance that
converts blue light into greenish yellow light, greenish yellow
being a complementary color of blue. The semiconductor light
emitting device outputs light that looks white by outputting (a) a
part of blue light that is emitted by a semiconductor light
emitting element and transmits translucent resin without being
converted by the luminescent substance, and (b) greenish yellow
light that is generated as a result of conversion by the
luminescent substance, at the same time in a proper proportion.
[0005] The details about the aforementioned semiconductor light
emitting device are disclosed in Japanese Patent Publication No.
3257455 and No. 3399440 filled by the applicants of the present
invention.
[0006] The aforementioned semiconductor light emitting device
comprises a submount substrate and a flip chip semiconductor light
emitting element that is mounted on the submount substrate, and
needs a space for wire bonding on the submount substrate.
Therefore, the submount substrate needs to be larger than the
semiconductor light emitting element, and the semiconductor light
emitting element is mounted on the submount substrate in an
unbalanced position where a center of the semiconductor light
emitting element does not coincide with a center of the submount
substrate. It should be noted here that generally a main surface of
the semiconductor light emitting element is substantially square
and a main surface of the submount substrate is substantially
rectangular.
[0007] Also, it is preferable that the semiconductor light emitting
device is equipped with a cup-like reflection member to reflect the
light emitted in parallel with a main light emitting surface by the
semiconductor light emitting element so that the light travels in a
direction perpendicular to a main light emitting surface.
[0008] The reflection member is a metal plate that has a
conical-trapezoidal-shaped hole, as one example. On a bottom of the
reflection member, the semiconductor light emitting element is
provided. Radius of the reflection member decreases from a top
toward a bottom.
[0009] Also a lens made of transparent resin or the like is
provided over the reflection member to improve light distribution
characteristic, and it is preferable to keep a radius on a bottom
as small as possible taking the amount of materials and light
focusing efficiency into account.
[0010] However, taking a light distribution characteristic into
consideration, if a center of main light emitting surface of the
semiconductor light emitting element is adjusted to coincide with a
center of the reflection member, a space for wire bonding sticks
out from the main light emitting surface. This would make a radius
on a bottom of the reflection member considerably larger than a
shape of the submount substrate. Nonetheless, adjusting a center of
the submount substrate to coincide with a center of the reflection
member should be avoided because it causes a degradation of light
distribution characteristic. Also, reducing a space for wire
bonding should be avoided because it increases bonding defects,
lowers a yield ratio, and diminishes productivity due to an effort
to improve accuracy.
[0011] The aim of the present invention is to provide a
semiconductor light emitting device that can be set in a smaller
space than the conventional ones without sacrificing light
distribution characteristic and productivity and to provide a
method for manufacturing the semiconductor light emitting
device.
DISCLOSURE OF THE INVENTION
[0012] The semiconductor light emitting device of the present
invention comprises an element to emit light and a substrate on a
main surface of which the element is mounted. The main surface of
the substrate composed of two areas, (i) a mount area which is
rectangular and on which the element is mounted, and (ii) a pad
area that is equipped with a pad for wire bonding. Here, the pad
area is contiguous to the mount area on one side of the mount area,
and the pad area decreases in width continuously or stepwise in a
direction away from the one side.
[0013] With this structure, a width of the pad area decreases with
the distance from the element. This enables to keep a space for
wire bonding without being inferior to the prior art, and to
decrease a radius of a bottom of a cup-like reflection member with
attention to light distribution characteristic by adjusting a
center of a main light emitting surface of the element to coincide
with a center of the reflection member. Therefore, it is possible
to reduce the amount of materials and to improve light focusing
efficiency.
[0014] Also, this structure has only two areas, the mount area and
the pad area, on the main surface of the substrate. In other words,
there is no wasted space on the substrate. This allows greater
flexibility to cut off substrates from an array substrate such as a
silicon wafer and to increase the number of substrates that can be
cut off from an array substrate, compared with circular or
polygonal substrates (a hexagon substrate, for one example) on
which an element needs to be mounted in a middle.
[0015] Consequently, according to the present invention, it is
possible to set a semiconductor light emitting element in a smaller
space than the conventional ones without sacrificing light
distribution characteristic and productivity.
[0016] A shape of the pad area of the semiconductor light emitting
device can be an isosceles trapezoid whose long base coincides with
the one side.
[0017] With this arrangement, since the pad area is an isosceles
trapezoid, it is possible to make the pad area easily just by
cutting off diagonally two corners of the conventional rectangle
pad area.
[0018] Also, a shape of the pad area of the semiconductor light
emitting device can be an isosceles triangle whose base coincides
with the one side.
[0019] With this arrangement, since the pad area is an isosceles
triangle, it is possible to make the pad area easily just by
cutting off diagonally two corners of the conventional rectangle
pad area.
[0020] Also, a shape of the pad area of the semiconductor light
emitting device can be a circular arc whose chord coincides with
the one side.
[0021] With this arrangement, since the pad area is a circular arc,
it is possible to set the semiconductor light emitting device along
a form of a reflection member, and to keep a space for wire
bonding. Therefore, it is possible to further reduce a radius on a
bottom of a reflection member.
[0022] Also, a shape of the pad area of the semiconductor light
emitting device can be a half regular polygon obtained by dividing
a regular polygon by a symmetrical line, and a longest side of the
half regular polygon coincides with the one side.
[0023] With this arrangement, since the pad area is a half regular
polygon, it is possible to make the pad area just by cutting off as
many sides of the pad area as needed. The larger the number of
sides of the polygon is, the larger a space for wire bonding is.
Thus, it is possible to further reduce a radius of a bottom of a
reflection member where the semiconductor light emitting device is
provided.
[0024] Further, the semiconductor light emitting device may
comprises a phosphor to change a wavelength of the light emitted by
the element. The element can be mounted substantially in the center
of the mount area, and the mount area can be covered entirely
together with the element, by the phosphor.
[0025] With this arrangement, since the mount area is covered
entirely by the phosphor, it is possible to cut the phosphor in a
horizontal direction along with three sides of the substrate when
cutting off substrates from an array substrate by dicing.
Therefore, it is possible to diminish deviation in thicknesses of
the phosphor without increasing a manufacturing process, and to
diminish deviation in colors and partial discoloration.
[0026] Also, in the semiconductor light emitting device, an
electrode that is included in the element and is connected to the
pad can be positioned substantially in the center of one of two
sides of the mount area that is connected to the one side.
[0027] With this arrangement, in the pattern where the substrates
are arranged to face respectively right and left to increase the
number of substrates that can be cut off from an array substrate,
it is possible to bond the elements while they face the same
direction when bonding the elements on an array substrate by die
bonding. Therefore, a mechanism to turn elements needs not to be
equipped in a die bonding machine.
[0028] Also the semiconductor light emitting device may further
comprises a cup-like reflection member to reflect the light that is
emitted in parallel with the main surface by the element so that
the light travels in a direction perpendicular to the main surface,
and a center of a main light emitting surface of the element
coincides with a center of the reflection member.
[0029] With this arrangement, the reflection member enables to
reflect the light emitted in parallel with a main light emitting
surface by the element so that the light travels in a direction
perpendicular to the main surface. Therefore, it is possible to
improve luminous efficiency. Further, light distribution
characteristic is improved and luminous unevenness can be
diminished by adjusting a center of a main light emitting surface
of the element to coincide with a center of the reflection
member.
[0030] Also, the semiconductor light emitting device may further
comprise a lens to output the light emitted by the element toward
an object. Here, a center of the main light emitting surface of the
element coincides with an optical center of the lens.
[0031] With this arrangement, the lens enables to output the light
emitted by the element toward an object. Therefore, it is possible
to improve light distribution characteristic and light directional
characteristic. Further, a light distribution characteristic is
improved and luminous unevenness can be diminished by adjusting a
center of a main light emitting surface of the element to coincide
with an optical center of the lens.
[0032] The method for manufacturing the semiconductor light
emitting device of the present invention comprises (a) an array
substrate generating step for generating an array substrate of
substrates arranged in a unique arrangement pattern, (b) a die
bonding step for bonding elements respectively on the substrates
arranged in the array substrate by die bonding, and (c) a cutting
step for cutting the array substrate into individual semiconductor
light emitting devices by dicing. Here, in the arrangement pattern
mentioned above, a side of the mount area that is opposite to the
one side is adjoined by a side of another mount area for another
element, with two elements on the mount area and said the another
mount area adjoining back to back.
[0033] With this arrangement, it is possible to increase the number
of substrates that can be cut off from an array substrate.
[0034] The method for manufacturing the semiconductor light
emitting device may further include an applying step, between the
die bonding step and the dicing step, for applying the phosphor to
the elements in a unique application pattern. Here, in the
application pattern, the phosphor is applied collectively to the
two elements that are adjoining back to back centering on the
adjoining sides.
[0035] With this arrangement, it is possible to apply the phosphor
collectively to the elements adjoined back to back. Therefore,
manufacturing efficiency is improved.
[0036] Also, the phosphor can be cut off at the same time when
cutting off substrates from an array substrate by dicing.
Therefore, it is possible to diminish deviation in thicknesses of
the phosphor without increasing a manufacturing process.
[0037] Also, in the die bonding step of the method for
manufacturing the semiconductor light emitting device, an electrode
that is included in the element and is connected to the pad can be
positioned substantially in the center of one of two sides of the
mount area that is connected to the one side, and such that all of
the elements face the same direction.
[0038] With this arrangement, it is possible to bond the elements
while they face the same direction when bonding the elements on the
array substrate by die bonding. Therefore, a mechanism to turn
elements needs not to be equipped in a die bonding machine.
[0039] The method for manufacturing the semiconductor light
emitting device of the present invention may includes (a) an array
substrate generating step for generating an array substrate of
substrates arranged in a unique arrangement pattern, (b) a mount
step for mounting the elements respectively on the substrates in
the array substrate, and (c) a cutting step for cutting the array
substrate into individual semiconductor light emitting devices by
dicing. Here, in the arrangement pattern, (i) even number rows in
which substrates that each have a mount area on the left and a pad
area on the right are connected with each other in a left-right
direction and (ii) odd number rows in which substrates that each
have a mount area on the right and a pad area on the left are
connected with each other in left-right direction, may be aligned
alternately.
[0040] With this arrangement, it is possible to increase the number
of substrates that can be cut off from an array substrate.
[0041] The method for manufacturing the semiconductor light
emitting device may further include an applying step, between the
die bonding step and the cutting step, for applying the phosphor to
the elements in a unique application pattern. Here, in the
arrangement pattern, there are margins between two elements
adjoining in rows, and in the application pattern, deviation of an
application width is controlled by the margins.
[0042] With this arrangement, it is possible to improve
productivity because the margins enable to control deviation of an
application width.
[0043] Also, in the die bonding step of the method for
manufacturing the semiconductor light emitting device, an electrode
that is included in the element and is connected to the pad can be
positioned substantially in the center of one of two sides that is
connected to the one side, and such that all of the semiconductor
light emitting elements face the same direction.
[0044] With this arrangement, it is possible to bond the elements
while they face the same direction when bonding the elements on
substrates by die bonding, therefore, a mechanism to turn elements
needs not to be equipped in a die bonding machine.
BRIEF DESCRIPTION OF THE DRAWING
[0045] FIG. 1 shows an appearance of a lighting device 10 that
comprises a number of light emitting modules respectively including
semiconductor light emitting devices of the first embodiment.
[0046] FIGS. 2A and 2B show details of the light emitting module 20
of FIG. 1. FIG. 2 shows the light emitting module 20 without a lens
viewed at a point where the light is received therefrom. FIG. 2B is
a cross sectional view of the light emitting module 20 taken along
the line A-A'.
[0047] FIG. 3A shows an appearance of the semiconductor light
emitting device 100 described in the first embodiment.
[0048] FIG. 3B shows the semiconductor light emitting device 100 of
FIG. 3A viewed at a point where the light is received
therefrom.
[0049] FIG. 3C is a front view of the semiconductor light emitting
device 100 of FIG. 3B.
[0050] FIG. 4 is a schematic diagram showing a method for
manufacturing the semiconductor light emitting device 100 of the
first embodiment.
[0051] FIG. 5 shows one example of the arrangement patterns unique
to the present invention.
[0052] FIG. 6 shows one example of the sheets of the submount
substrates 130 on which all of the semiconductor light emitting
elements 110 are connected by bump connecting.
[0053] FIG. 7 shows one example of the sheets of the submount
substrates 130 on which a phosphor is applied/printed in a unique
application pattern.
[0054] FIG. 8A and FIG. 8B show semiconductor light emitting
devices whose pad areas are trapezoids viewed at a point where the
light is received therefrom. In a semiconductor light emitting
device 300 shown in FIG. 8A, the mount area has an extended long
side. In a semiconductor light emitting device 310 shown in FIG.
8B, the mount area has a not-remarkably-extended long side.
[0055] FIG. 9A and FIG. 9B show semiconductor light emitting
devices whose pad areas are triangles viewed at a point where the
light is received therefrom. In a semiconductor light emitting
device 320 shown in FIG. 9A, the mount area has an extended long
side. In a semiconductor light emitting device 330 shown in FIG.
9B, the mount area has a not-remarkably-extended long side.
[0056] FIG. 10A and FIG. 10B show light emitting devices whose pad
areas are circular arcs viewed at a point where the light is
received therefrom. In a semiconductor light emitting device 340
shown in FIG. 10A, the mount area has an extended long side. In a
semiconductor light emitting device 350 shown in FIG. 10B, the
mount area has a not-remarkably-extended long side.
[0057] FIG. 11A and FIG. 11B show semiconductor light emitting
devices whose pad areas are half regular polygons (Octagon is used
in the drawing) viewed at a point where the light is received
therefrom. In a semiconductor light emitting device 360 shown in
FIG. 10A, the mount area has an extended long side. In a
semiconductor light emitting device 370 shown in FIG. 10B, the
mount area has a not-remarkably-extended long side.
[0058] FIG. 12 shows one example of the arrangement patterns unique
to the present invention.
[0059] FIG. 13 is one example of the sheets of the submount
substrates on which all of the semiconductor light emitting
elements are connected by bump connecting.
[0060] FIG. 14 shows one example of the sheets of submount
substrates 130 when the phosphor is applied/printed in an
application pattern unique to the present invention.
[0061] FIG. 15 shows other example of the arrangement patterns
unique to the present invention.
[0062] FIG. 16 is other example of the sheets of submount
substrates 130 on which all of the semiconductor light emitting
elements are connected by bump connecting.
[0063] FIG. 17 shows other example of the sheets of the submount
substrates 130 when the phosphors are applied/printed in an
application pattern unique to the present invention.
[0064] FIG. 18 is other example of the arrangement patterns unique
to the present invention.
[0065] FIG. 19 is other example of the sheets of submount
substrates on which all of semiconductor light emitting elements
110 are connected by bump connecting.
[0066] FIG. 20 shows other example of the sheets of submount
substrates 130 when the phosphors are applied/printed in an
application pattern unique to the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
First Embodiment
<General Description>
[0067] The inventors of the present application focused attention
on a point that corners of a space for wire bonding on conventional
rectangular substrates do not function efficiently as a pad for
wire bonding, in spite that the corners are one of the factors that
affect a minimum size of cup-like reflection members and lenses.
This embodiment provides a semiconductor light emitting device in
which corners of a space for wire bonding are improved in shape.
The semiconductor light emitting device of the present invention
can be set in a smaller space than conventional ones without
sacrificing light distribution characteristic and productivity.
Also, the semiconductor light emitting device of the present
invention enables to reduce the amount of materials and to improve
light focusing efficiency.
<Structure>
[0068] FIG. 1 shows an appearance of a lighting device 10 that
comprises a number of light emitting modules respectively including
semiconductor light emitting devices of the first embodiment.
[0069] As shown in FIG. 1, the lighting device 10 of the first
embodiment is a light emitting panel that outputs white light to be
used for illuminations, and comprises eight terminals 11 to receive
an electric supply and sixty-four light emitting modules 20 that
are arranged in an eight-by-eight matrix. The lighting device 10
outputs white light by connecting the outer terminals 11 to a power
source and making each of the light emitting module 20 emit
light.
[0070] FIGS. 2A and 2B show details of the light emitting module 20
of FIG. 1. FIG. 2 shows the light emitting module 20 without a lens
viewed at a point where the light is received therefrom. FIG. 2B is
a cross sectional view of the light emitting module 20 taken along
the line A-A'.
[0071] As shown in FIG. 2A and FIG. 2B, the light emitting module
20 comprises a device substrate 21, a wiring pattern 22, a bonding
wire 23, a reflecting unit 24, a lens unit 25, and a semiconductor
light emitting device 100. Here, the semiconductor light emitting
device 100 is indicated by a shaded part.
[0072] The device substrate 21 is a board made of aluminum-based
alloy, for example. It is preferable that the device substrate 21
is made of a material that is able to maintain a rigidity of the
lighting device 10, and has a high heat conductance to efficiently
discharge heat generated by the semiconductor light emitting device
100.
[0073] The wiring pattern 22 is metal foil such as copper foil
formed on a main surface of the device substrate 21. The wiring
pattern 22 includes (a) a first electrode 26 that is positioned at
least in a part on which the semiconductor light emitting device
100 is to be bonded by die bonding and is electrically connected to
one of the outer terminals 11 and (b) a second electrode 27 that is
positioned at least in a part where the bonding wire 23 is to be
bonded by wire bonding and is electrically connected to another one
of the outer terminals 11. It should be noted here that the first
electrode 26 and the second electrode 27 are arranged to be
slightly widened to reflect upward the light that comes
downward.
[0074] The bonding wire 23 is an electric conductor made of, for
example, gold or aluminum, and connects a bonding pad on the
semiconductor light emitting device 100 and the second electrode
27.
[0075] The reflecting unit 24 is made by boring holes that are
circular in a cross section in a metal plate made of, for example,
aluminum. The holes are bored to fit each of the light emitting
module 20, and radii of the holes increase as the distance from a
bottom where the semiconductor light emitting element is provided
increases. The reflecting unit 24 also can be made by providing
conical-trapezoidal cup-like reflection members on a metal plate,
radii of reflection members decreasing toward a bottom. The
reflection members are provided to fit each of the light emitting
module 20. The reflecting unit 24 is equipped to reflect the light
that is emitted in parallel with a main light emitting surface by
the semiconductor light emitting device 100 so that the light
travels in a direction perpendicular to the main light emitting
surface. Also, by adjusting a center of a main light emitting
surface of the semiconductor light emitting device 100 to coincide
with a center of the reflecting unit 24, light distribution
characteristic is improved and luminous unevenness is
diminished.
[0076] The lens unit 25 is made of resin such as epoxy resin and is
formed according to a transfer forming method. The lens unit 25 is
used to output light emitted by the semiconductor light emitting
device 100 toward an object. It is preferable to restrict the use
of filler to improve light transmission of epoxy resin. Therefore,
highly-purified epoxy resin with no filler is used for the lens
unit 25. Also, by adjusting a center of a main light emitting
surface of the semiconductor light emitting device 100 to coincide
with an optical center of the lens unit 25, light distribution
characteristic is improved and luminous unevenness is
diminished.
[0077] FIG. 3A shows an appearance of the semiconductor light
emitting device 100 described in the first embodiment.
[0078] FIG. 3B shows the semiconductor light emitting device 100 of
FIG. 3A viewed at a point where the light is received
therefrom.
[0079] FIG. 3C is a front view of the semiconductor light emitting
device 100 of FIG. 3B.
[0080] As shown in FIG. 3A, FIG. 3B, and FIG. 3C, the semiconductor
light emitting device 100 is a device to output white light, and
comprises a semiconductor light emitting element 110, a translucent
resin 120, and a submount substrate 130.
[0081] The semiconductor light emitting element 110 is an element
to emit light whose main surface is rectangular, such as a light
emitting diode that comprises a substrate having an optical
transparency on which a GaN chemical compound semiconductor layer
is formed and emits blue light. The semiconductor light emitting
element 110 comprises a sapphire substrate 111 that has
translucency, a semiconductor layer 112 comprising an n type light
emitting layer and a p type light emitting layer, a p electrode 113
that is connected to the p type light emitting layer, and an n
electrode 114 that is connected to the n type light emitting layer.
The semiconductor light emitting element 110 has the p electrode
113 and the n electrode 114 on the main surface facing the submount
substrate 130, and the other main surface is a main light emitting
surface that chiefly emits light. Here, the semiconductor light
emitting element 110 is a rectangular parallelepiped whose main
surface being 3 mm square and thickness being 0.1 mm, and is
mounted on the submount substrate 130 as shown in FIG. 3.
[0082] The translucent resin 120 scatteredly includes luminescent
substance (not shown in drawings) that converts blue light into
greenish yellow light, greenish yellow being a complementary color
of blue. The translucent resin 120 is a translucent phosphor made
of a resin material that transmits (a) blue light which has not
been converted to greenish yellow light by the luminescent
substance and (b) greenish yellow light which has been generated as
a result of conversion by the luminescent substance. The
translucent resin 120 is mounted on the submount substance 130 as
shown in FIG. 3 to cover the submount substrate 130 and its
surrounding area.
[0083] The submount substrate 130 includes a silicon substrate 140
that is a protective diode such as a zener diode made of basically
silicon. The submount substrate 130 is a substrate on which the
semiconductor light emitting element 110 and the translucent resin
120 are mounted, and has a first counter electrode 131, a second
counter electrode 132, and bump electrodes 133 and 134 on a mount
surface that is a main surface of the silicon substrate 140 and has
the semiconductor light emitting element 110 and the translucent
resin 120 thereon. Also, a back-side electrode 135 is provided on a
main surface of the silicon substrate 140 opposite to the mount
surface.
[0084] The silicon substrate 140 comprises, (a) an n type
semiconductor area 141 adjoining the first counter electrode 131
and (b) a p type semiconductor area 142 adjoining the second
counter electrode 132. Also, at least the counter electrode 132 is
provided on a part of the mount surface that is not covered by the
translucent resin 120, and this part is to be a bonding pad 136 to
be used for wire bonding.
[0085] The following explains a shape of the main surface of the
submount substrate 130. The main surface of the submount substrate
130 is slightly larger than a main surface of the semiconductor
light emitting element 110, and composed of two areas, (i) a mount
area which is a rectangle and on which the semiconductor light
emitting element 110 and the translucent resin 120 are mounted and
(ii) a pad area that is equipped with the bonding pad 136. Here,
the pad area is contiguous to the mount area on one side of the
mount area, and the pad area decreases in width continuously or
stepwise in a direction from the one side.
[0086] Here, the main surface of the submount substrate 130
comprises a rectangular mount area whose short sides being 0.4 mm
and long sides being 0.42 mm, and an isosceles trapezoidal pad area
whose long base being 0.4 mm, short base being 0.12 mm, and a
height being 0.14 mm. The short side of the mount area is
contiguous to the long base of the pad area, and a thickness is 0.2
mm. It should be noted here that the long base of the pad area
denotes a longer side of parallel sides of an isosceles
trapezoid.
[0087] Also, various diodes such as a zener diode, a pn diode, a
pin diode, a shottky barrier diode, a tunnel diode, and a gun diode
can be used as the silicon substrate 140.
[0088] Here, the silicon substrate 140 that is a protective diode
is connected with the semiconductor light emitting element 110 that
is a light emitting diode, by electrodes that have reversed
polarities. With such an arrangement in which a protective diode is
connected with a light emitting diode, even if an attempt is made
to apply a reverse voltage to the light emitting diode, a reverse
voltage is hardly applied to the light emitting diode because
electric current flows forward to the protective diode. Also, even
if an attempt is made to apply an excessive forward voltage to the
light emitting diode, a higher voltage than a reverse breakdown
voltage (a zener voltage) of the protective diode is not applied.
In a case where a silicon diode is used as the protective diode,
usually a forward voltage can be set at approximately 0.9 V, a
reverse breakdown voltage at approximately 10 V. On the other hand,
a forward breakdown voltage of a GaN light emitting diode is
approximately 100V, and a reverse breakdown voltage is
approximately 30V. Therefore, it is possible to assuredly prevent a
light emitting diode from being destroyed by an excessive voltage
due to static electricity and such.
[0089] A light emitting diode that emits blue light is mainly
GaN-based, and has less resistance to static electricity compared
with other bulk chemical compound semiconductors GaP-based or
GaAlAs-based. Therefore, the arrangement in which various diodes
are used in the submount substrate 130 produces great effect.
However, the submount substrate 130 may not necessarily be composed
of diodes in cases where other measures are taken against static
electricity or where a semiconductor light emitting element such as
other bulk chemical compound semiconductors that has high
resistance to static electricity is used.
[0090] The first counter electrode 131 is electrically connected to
the p electrode 113 equipped on the semiconductor light emitting
element 110, by the bump electrode 133, and the second counter
electrode 132 is electrically connected to the n electrode 114
equipped on the semiconductor light emitting element 110, by the
bump electrode 134. When a voltage is applied between the first
counter electrode 131 and the second counter electrode 132, the
light emitting element 110 emits light.
[0091] It should be noted here that the light emitting element 110
is not limited to an element that emits blue light. An element that
emits ultraviolet light can be the light emitting element 110 as an
example. In this case, a translucent resin 120 includes luminescent
substance that excites the ultraviolet light emitted by the
semiconductor light emitting element 110 to emit blue light, red
light and green light, and is a translucent phosphor comprising
resin material that transmits the blue light, the red light, and
the green light which is generated by the luminescent
substance.
<Method for Manufacture>
[0092] FIG. 4 is a schematic diagram showing a method for
manufacturing the semiconductor light emitting device 100 of the
first embodiment.
[0093] The following describes a method for manufacturing the
semiconductor light emitting device 100 with reference to FIG.
4.
[0094] (1) A sheet of the submount substrates 130 (an array
substrate) is manufactured by manufacturing a wafer of the silicon
substrate 140 which is a zener diode made of basically silicon and
by equipping the wafer with the first counter electrodes 131, the
second counter electrodes 132 and the back-side electrode 135 (Step
S1). Here, the present method differs from the conventional method
in that it uses a unique arrangement pattern.
[0095] FIG. 5 shows one example of the arrangement patterns unique
to the present invention.
[0096] In FIG. 5, the submount substrates 130 are indicated by
shaded parts, and each broken line indicates positions to be cut by
dicing. When cutting off a shaded part 200 at the upper left, for
example, it is preferable to cut it along the broken lines in the
ascending order of the reference numbers, from 201 to 206, because
chipping can be prevented by cutting longer side first.
[0097] (2) A wafer of the semiconductor light emitting elements 110
is manufactured and attached onto a dicing tape. Then after being
divided into chips by dicing, the wafer is expanded together with
the dicing tape so that each chip of the semiconductor light
emitting element 110 can be picked up easily (Step S2).
[0098] (3) The sheet of the submount substrates 130 is put in place
on a XY table for bump connecting based on the shape and an
alignment mark on the sheet (Step S3).
[0099] (4) The dicing tape on which the semiconductor light
emitting elements 110 are attached is put in a place on a XY table
for picking up substrates (Step 4).
[0100] (5) Bump electrodes 133 and 134 are generated at each
position on the submount substrates 130 where the semiconductor
light emitting element 110 is to be connected by bump connecting
(Step S5).
[0101] (6) The semiconductor light emitting elements 110 are picked
up one by one from the dicing tape by moving the XY table for bump
connecting. On a midway stage, accuracies of directions and
positions are improved, and the semiconductor light emitting
elements 110 are connected to each of the submount substrate 130 by
bump connecting (Step S6).
[0102] (7) After the semiconductor light emitting elements 110 are
respectively connected to all of the submount substrates 130 on the
sheet, the sheet is transferred to a phosphor printer employing a
metal plate (Step 7).
[0103] FIG. 6 shows one example of a sheet of the submount
substrates 130 on which all of the semiconductor light emitting
elements 110 are connected by bump connecting.
[0104] In FIG. 6, the semiconductor light emitting elements 110 are
indicated by shaded parts, and each of the broken line indicates
positions to be cut by dicing.
[0105] (8) In the phosphor printing press, a phosphor is
applied/printed on the semiconductor light emitting elements 110
and their surroundings in a unique application pattern (Step
S8).
[0106] FIG. 7 shows one example of the sheets of the submount
substrates 130 on which the phosphor is applied/printed in a unique
application pattern.
[0107] In FIG. 7, the phosphors applied/printed on the sheet are
indicated by shaded parts, and broken lines indicate positions to
be cut by dicing.
[0108] (9) The semiconductor light emitting device 100 is completed
after the sheet is divided into each submount substrate 130 by
dicing (Step 9).
[0109] Here, when the submount substrates 130 are cut off from the
sheet by dicing, margins between elements that are adjacent in the
row and column directions are cut off along three sides of the
phosphor. Therefore, with an application pattern unique to the
present invention, it is easy to control deviation of an
application width. For example, in FIG. 7, a translucent resin 120
at the upper left is formed by cutting along three sides of the
phosphor that are shown by broken lines 201, 202, and 203.
<Summary>
[0110] As described above, according to the semiconductor light
emitting device of the first embodiment, corners of a wire bonding
area of the rectangular submount substrates are improved in shape,
and it is possible to reduce the minimum size of reflection members
and lenses.
[0111] Consequently, it is possible to set in a smaller space, to
reduce the amount of materials, and to improve light focusing
efficiency without sacrificing light distribution characteristic
and productivity as compared with conventional light emitting
devices.
Modification Example 1
[0112] The modification example 1 of the present invention shows a
modification of a shape of the pad area described in the first
embodiment.
[0113] The shape of the pad area is not limited to isosceles
trapezoidal described in the first embodiment. The pad area can be
other trapezoids, isosceles triangles, other triangles, circular
arcs, and half regular polygons.
[0114] FIG. 8A and FIG. 8B show semiconductor light emitting
devices whose pad areas are trapezoids viewed at a point where the
light is received therefrom. In a semiconductor light emitting
device 300 shown in FIG. 8A, the mount area has an extended long
side. In a semiconductor light emitting device 310 shown in FIG.
8B, the mount area has a not-remarkably-extended long side.
[0115] In the semiconductor light emitting devices 300 and 310, the
long base of the isosceles trapezoid coincides with a short side of
the mount area.
[0116] FIG. 9A and FIG. 9B show semiconductor light emitting
devices whose pad areas are triangles viewed at a point where the
light is received therefrom. In a semiconductor light emitting
device 320 shown in FIG. 9A, the mount area has an extended long
side. In a semiconductor light emitting device 330 shown in FIG.
9B, the mount area has a not-remarkably-extended long side.
[0117] In the semiconductor light emitting devices 320 and 330, a
base of the isosceles triangle coincides with a short side of the
mount area.
[0118] FIG. 10A and FIG. 10B show light emitting devices whose pad
areas are circular arcs viewed at a point where the light is
received therefrom. In a semiconductor light emitting device 340
shown in FIG. 10A, the mount area has an extended long side. In a
semiconductor light emitting device 350 shown in FIG. 10B, the
mount area has a not-remarkably-extended long side.
[0119] In the semiconductor light emitting devices 340 and 350, a
chord of the circular arc coincides with a short side of the mount
area.
[0120] FIG. 11A and FIG. 11B show semiconductor light emitting
devices whose pad areas are half regular polygons (Octagon is used
in the drawing) viewed at a point where the light is received
therefrom. In a semiconductor light emitting device 360 shown in
FIG. 10A, the mount area has an extended long side. In a
semiconductor light emitting device 370 shown in FIG. 10B, the
mount area has a not-remarkably-extended long side.
[0121] In the semiconductor light emitting devices 360 and 370
shown in FIG. 11A and FIG. 11B, a longest side of the half regular
polygon coincides with a short side of the mount area.
[0122] Here, in the semiconductor light emitting devices 300, 320,
340 and 360, long sides of mount areas are extended. Therefore, it
is easy to apply/print a translucent resin.
[0123] In the semiconductor light emitting devices 300 and 310, it
is possible to have a large space between a wire and the submount
substrate. Therefore, credibility is high. Also, the semiconductor
light emitting devices 300 and 310 can be simply made just by
cutting off diagonally two corners of the conventional rectangular
pad area.
[0124] In the semiconductor light emitting devices 320 and 330, it
is possible to reduce a radius of a bottom of the reflection
member. Therefore, reflection efficiency is improved. The
semiconductor light emitting devices 320 and 330 can be simply made
just by cutting off diagonally two corners of the conventional
rectangular mount area. Further, the semiconductor light emitting
device 330 has a large wire bonding area and exhibits high bond
quality.
[0125] The semiconductor light emitting devices 340 and 350 can be
set substantially along a form of the reflection member. Also it is
possible to keep a space for wire bonding and to reduce radius of a
bottom of a reflection member where the semiconductor light
emitting device is provided.
[0126] Further, the semiconductor light emitting devices 360 and
370 can be made just by cutting off as many sides of the pad areas
as needed, and the larger the number of sides of the polygons are,
the larger spaces for wire bonding are. Thus, it is possible to
further reduce a radius of a bottom of a reflection member where
the semiconductor light emitting device is provided.
Modification Example 2
[0127] The modification example 2 shows one example of arrangement
patterns unique to the present invention in a case where the pad
area is a triangle.
[0128] FIG. 12 shows one example of arrangement patterns unique to
the present invention.
[0129] In FIG. 12, shaded parts indicate the submount substrates
whose pad areas are triangles, and each broken line indicates
positions to be cut by dicing. When cutting off a shaded part 400
at the upper left, for example, it is preferable to cut it along
the broken lines in the ascending order of the reference numbers,
from 401 to 405, because chipping can be prevented by cutting the
longer sides first.
[0130] Also, in FIG. 12, it is possible to make the pad area
trapezoidal by cutting along the broken line 406 with a thick
blade.
[0131] FIG. 13 is one example of the sheets of the submount
substrates on which all of the semiconductor light emitting
elements are connected by bump connecting.
[0132] In FIG. 13, the semiconductor light emitting elements are
indicated by shaded parts, and each broken line indicates positions
to be cut by dicing.
[0133] Here, as shown in FIG. 13, the semiconductor light emitting
elements 110 are mounted on the submount substrates 130 such that
the n electrode 114 that is included in a semiconductor light
emitting element 110 and is connected to the pad is positioned
substantially in the center of a side of the mount area that is
connected to the one side, and such that all of the semiconductor
light emitting elements 110 face the same direction.
[0134] As described above, by making all of the semiconductor light
emitting elements 110 face the same direction, it is possible to
bond the semiconductor light emitting elements while they face the
same direction, when bonding the semiconductor light emitting
elements on the sheet by die bonding. Therefore, a mechanism to
turn elements needs not to be equipped in a die bonding
machine.
[0135] FIG. 14 shows one example of the sheets of submount
substrates 130 when the phosphor is applied/printed in an
application pattern unique to the present invention.
[0136] In FIG. 14, the phosphors that are applied/printed on the
submount substrates 130 are indicated by shaded parts, and each
broken line indicates positions to be cut by dicing.
[0137] As shown in FIG. 12, with the unique arrangement pattern, a
side of the mount area that is opposite to the one side is adjoined
by a side of another mount area for another element, with two
elements on the mount area and another mount area adjoining back to
back, and it is possible to increase the number of substrates that
can be cut off from the array substrate. Also, as shown in FIG. 14,
when applying/printing the phosphors, the phosphors can be
applied/printed collectively to two elements that are adjoining
back to back centering on the adjoining sides. Further, it is
possible to apply/print the phosphors onto lines together in a
vertical direction.
Modification Example 3
[0138] The modification example 3 shows other example of the
arrangement patterns unique to the present invention described in
the first embodiment in a case where the pad area is a
triangle.
[0139] FIG. 15 shows other example of the arrangement patterns
unique to the present invention.
[0140] In the FIG. 15, shaded parts indicate the submount
substrates whose pad areas are triangles, and each broken line
indicates positions to be cut by dicing. Here, when cutting off a
shaded part 410 at the upper left, for example, it is preferable to
cut it along the broken lines in the ascending order of the
reference numbers, from 411 to 415, because chipping can be
prevented by cutting the longer sides first.
[0141] Also, in FIG. 15, it is possible to make the pad area
trapezoidal by cutting along the broken line 416 with a thick
blade.
[0142] FIG. 16 is other example of the sheets of submount
substrates 130 on which all of the semiconductor light emitting
elements are connected by bump connecting.
[0143] In FIG. 16, the semiconductor light emitting elements 110
are indicated by shaded parts, and each broken line indicates
positions to be cut by dicing.
[0144] Here, as same as the modification example 2, the
semiconductor light emitting elements 110 are mounted on the
submount substrates 130 such that the n electrode 114 that is
included in the semiconductor light emitting element 110 and is
connected to the pad is positioned substantially in the center of a
side of the mount area that is connected to the one side, and such
that all of the semiconductor light emitting elements 110 face the
same direction.
[0145] As described above, by making all of the semiconductor light
emitting elements face the same direction, it is possible to bond
the semiconductor light emitting elements while they face the same
direction when bonding the semiconductor light emitting elements on
the sheet by die bonding. Therefore, a mechanism to turn elements
needs not to be equipped in a die bonding machine.
[0146] FIG. 17 shows other example of the sheets of the submount
substrates 130 when the phosphors are applied/printed in an
application pattern unique to the present invention.
[0147] In FIG. 17, phosphors that are applied/printed on the
submount substrates 130 are indicated by shaded parts, and each
broken line indicates positions to be cut by dicing.
[0148] As shown in FIG. 15, with the unique arrangement pattern, a
side of the mount area that is opposite to the one side is adjoined
by a side of another mount area for another element, with two
elements on the mount area and the another mount area adjoining
back to back, and it is possible to increase the number of
substrates that can be cut off from the array substrate. Also, when
applying/printing the phosphors on the elements, the phosphors can
be applied/printed collectively to the two elements that are
adjoining back to back centering on the adjoining sides. However,
this arrangement pattern is arranged to increase the number of
substrates that can be cut off from the array substrate, and it is
not possible to apply/print collectively in the longitudinal
direction as compared with the arrangement pattern of the
modification example 2. Therefore, as shown in FIG. 17, the
phosphors are applied/printed to be conical trapezoidal forms.
Modification Example 4
[0149] The modification example 4 shows other example of
arrangement patterns unique to the present invention described in
the first embodiment in a case where the pad area is a
triangle.
[0150] FIG. 18 is other example of the arrangement patterns unique
to the present invention.
[0151] In the FIG. 18, shaded parts indicate submount substrates
whose pad areas are triangles, and each broken line indicates
positions to be cut by dicing. Here, when cutting off a shaded part
420 at the upper left, for example, it is preferable to cut it
along the broken lines in the ascending order of the reference
number, from 421 to 425, because chipping can be prevented by
cutting the longer side first.
[0152] FIG. 19 is other example of the sheets of submount
substrates on which all of semiconductor light emitting elements
110 are connected by bump connecting.
[0153] In FIG. 19, the semiconductor light emitting elements 110
are indicated by shaded parts, and each broken line indicates
positions to be cut by dicing.
[0154] Here, as same as the modification example 2, the
semiconductor light emitting elements 110 are mounted on the
submount substrates 130 so that then electrode 114 that is included
in the semiconductor light emitting element 110 and is connected to
the pad is positioned substantially in the center of a side of the
mount area that is connected to the one side, and such that all of
the semiconductor light emitting elements 110 face the same
direction.
[0155] As described above, by making all of the semiconductor light
emitting elements 110 face same direction, it is possible to bond
the semiconductor light emitting elements while they face the same
direction when bonding semiconductor light emitting elements on the
sheet by die bonding. Therefore, a mechanism to turn elements needs
not to be equipped in a die bonding machine.
[0156] FIG. 20 shows other example of the sheets of submount
substrates 130 when the phosphors are applied/printed in an
application pattern unique to the present invention.
[0157] In FIG. 20, the phosphors that are applied/printed on the
submount substrates 130 are indicated by shaded parts, and each
broken line indicates positions to be cut by dicing.
[0158] As shown in FIG. 20, in the modification example 4, it is
possible to increase the number of substrates that can be cut off
from the array substrate. Also, the array substrate of the submount
substrates 130 has margins. Therefore, it is possible to control
deviation of an application width and to improve productivity.
[0159] It should be noted here that means to cut off the submount
substrates from the array substrate is not limited to the dicing
technique. Any technique such as lasers and sandblastings can be
used to cut off the submount substrates. For example, a laser
enables to cut in any form. Therefore, a laser can be applied in
any case including cases where making the pad area circular arcs or
half regular polygons.
INDUSTRIAL APPLICABILITY
[0160] The semiconductor light emitting device of the present
invention is able to apply to any lighting equipment and display.
Especially, it is possible to provide compact and lightweight light
sources. Therefore, the semiconductor light emitting device of the
present invention has a great deal of potential to install in
portable devices such as cellular-phones andc ameras.
* * * * *