Chip light-emitting device

Details Chip light-emitting device Chip light-emitting device

2001-01-02

2004-08-17

Jackson, Jerome (Department: 2815)

Active solid-state devices (e.g., transistors, solid-state diode

Incoherent light emitter structure

With housing or contact structure

C100S079000, C100S088000, C100S089000, C100S091000, C313S500000, C313S505000, C313S512000

Reexamination Certificate

active

06777719

ABSTRACT:

TECHNICAL FIELD
The present invention relates to the ultra small-sized chip type light emitting device using a light emitting diode (LED) chip which can obtain the symmetric luminous intensity distribution in a longitudinal direction on a board and can enhance wire bonding reliability.
BACKGROUND
A small-sized chip type light emitting device with a light emitting diode (LED) chip is known as a conventional light emitting source.
FIG. 2
is a perspective view showing an example of such chip type light emitting device.
FIG. 2
illustrates that a pair of electrode patterns
3
and
4
comprised of conductive layer such as copper (Cu) plate layer is formed at the both ends of the board
2
. One electrode pattern
3
consists of the surface electrode
3
a
, side face electrode
3
b
and back electrode
3
c.
The other electrode pattern
4
also consists of the surface electrode
4
a
, side face electrode
4
b
and back electrode
4
c
. The side face electrode
3
b
and side face electrode
4
b
of a pair of electrode patterns
3
and
4
form several elliptical through holes in parallel on an original large-sized board on which the board
2
can be obtained by dividing, the internal surface of the elliptical though holes is plated with Cu, etc., and the surface electrodes
3
a
/
4
a
and back electrodes
3
c
/
4
c
of a pair of electrode patterns
3
and
4
are connected to each other.
The pad
3
p
is formed on the surface electrode
3
a
of one electrode pattern
3
and the LED chip
1
is mounted there by die-bonding. One end
5
a
of the metal wire
5
is connected electrically to the electrode
1
a
of the LED chip
1
by wire bonding. The other end
5
b
of the metal wire
5
is connected electrically to the surface electrode
4
a
of the other electrode pattern
4
by wire bonding. The ultrasonic wave is used in this wire bonding.
The LED chip
1
mounted on the board
2
, in which the lower electrode is connected to the surface electrode
3
a
of one electrode pattern
3
by the wiring bonding, and the metal wire
5
connected electrically to the upper electrode
1
a
of the LED chip
1
and to the surface electrode
4
a
of the other electrode pattern
4
by wire bonding are sealed with the translucent resin mold
6
. The positions of both ends of this translucent resin mold
6
are located separately from each other at the inside of both ends of the board
2
. The chip type light emitting device
20
is formed as mentioned above.
At the handling such as transportation, etc. for automatic mounting to a printed board, etc., the translucent resin mold
6
is picked up by a chuck and the chip type light emitting device
20
is transferred. In the configuration shown in
FIG. 2
, both ends of the translucent resin mold
6
are located at the inside of the surface electrodes
3
a
and
4
a
of a pair of electrode patterns
3
and
4
. Therefore, the length of the translucent resin mold
6
is shorter than that of the board
2
of the chip type light emitting device
20
, and the contact area for picking up becomes smaller, so if the size of the board
2
becomes 1.6 mm (length)×0.8 mm (width) or less, the handling cannot be performed smoothly.
FIG.
3
and
FIG. 4
are perspective views showing an example of conventional another chip type light emitting device and the example illustrates that the semi-circular notches
7
and
8
have been formed at both ends of the board
2
.
FIG. 5
is a characteristics diagram showing the distribution of luminous intensity I of the chip type light emitting device of FIG.
3
. In FIG.
3
and
FIG. 4
, the same places as
FIG. 2
or the points corresponding to
FIG. 2
are marked with the same symbols. In the example of
FIG. 3
, the side face electrodes
3
b
and
4
b
of a pair of electrode patterns
3
and
4
are formed at the internal face of the semi-circular notches
7
and
8
which are formed at both ends of the board
2
.
The surface electrodes
3
a
and
4
a
of a pair of electrode patterns
3
and
4
extend to a place where those electrodes cover the upper faces of the notches
7
and
8
and both ends of the translucent resin mold
6
and both longitudinal ends of the board
2
are aligned. In the example of
FIG. 3
, the surfaces of the notches
7
and
8
are covered with the surface electrodes
3
a
and
4
a
of a pair of electrode patterns
3
and
4
. Therefore, the resin does not flow into the notches
7
and
8
when the translucent resin mold
6
is processed.
In the example of
FIG. 3
, both ends of the translucent resin mold
6
are located at both longitudinal ends of the board
2
. Therefore, this example has the advantage of securing the surface area of the translucent resin mold
6
to the extent that the said handling can be performed smoothly even if the chip type light emitting device
30
is downsized.
However, assuming that both ends of the translucent resin mold
6
are located at both longitudinal ends of the board
2
as shown in
FIG. 3
, if the board size becomes small, e.g., 1.6 mm×0.8 mm, the LED chip cannot be centered on the board
2
as shown in FIG.
4
.
In the example of chip type light emitting device
40
of
FIG. 4
, the LED chip
1
is mounted at a position shifted to a longitudinal center of the board
2
and the other end
5
b
of the metal wire
5
is bonded at a position close to the end of the board
2
. That is, the other end
5
b
of the metal wire
5
is bonded at a position where the surface electrode
4
b
of the electrode pattern
4
covers the notch
8
.
As described above, a position to bond the other end
5
b
of the metal wire is located on the surface electrode
4
b
which covers the upper face of the notch
8
. Therefore, the notch
8
is located under a place where wire bonding is performed and the mechanical strength of horn support deteriorates at wire bonding with the ultrasonic wave.
Therefore, enough pressure cannot be applied to the horn which propagates the ultrasonic wave at the ultrasonic wave processing and the surface electrodes
4
b
of the electrode pattern
5
and the other end
5
b
of the metal wire cannot be bonded completely to each other by the ultrasonic wave. To enhance the reliability of bonding with the ultrasonic wave, the configuration illustrated in
FIG. 3
is adopted. However, in
FIG. 3
, the LED chip
1
is mounted at the off-centered position on the board
2
.
In the example of
FIG. 3
, the LED chip
1
cannot be centered on the board
2
. As a result, the LED chip
1
is located at the decentered position on the translucent resin mold
6
also. So, as shown in the luminous intensity characteristics diagram of
FIG. 5
, there was a problem that the symmetric luminous intensity distribution cannot be obtained in a longitudinal direction of the board.
DISCLOSURE OF INVENTION
The present invention was made taking such problem into consideration and the purpose of the present invention is to offer the ultra small-sized chip type light emitting device which can obtain the symmetric luminous intensity distribution in a longitudinal direction of the board even if the board is downsized and which can enhance wire bonding reliability.
The chip type light emitting device offered by the present invention comprising: a board of nearly rectangular shape in a plane view; first and second electrode patterns formed at both ends of a surface of the board; a light emitting diode (LED) chip mounted on the first electrode pattern; a metal wire connected to the LED chip and the second electrode pattern by wire bonding; and a translucent resin mold which seals the LED chip and the metal wire;
wherein one notch is formed at one end of the board at the first electrode pattern side and two notches are formed at both sides of the other end of the board at the second electrode pattern side, and the positions at both ends of the translucent resin mold are arranged to the positions at both ends in a longitudinal direction of the board.
The preferred embodiment of the present invention features that the LED is almost centered on the board.
The preferred embo

Affiliated with

Also associated with

Rating

Chip light-emitting device does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Chip light-emitting device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Chip light-emitting device will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3296276