Optical: systems and elements – Optical modulator – Light wave temporal modulation
Reexamination Certificate
2002-02-11
2004-04-06
Ben, Loha (Department: 2873)
Optical: systems and elements
Optical modulator
Light wave temporal modulation
C359S248000, C359S254000, C385S014000, C385S088000, C438S014000, C438S026000, C438S029000, C438S106000, C438S464000, C257S094000, C257S704000, C250S332000
Reexamination Certificate
active
06717711
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a structure and a method for forming an electro-optics device. More particularly, the present invention relates to a method and a structure for forming a high efficiency electro-optics device.
BACKGROUND OF THE INVENTION
Many kinds of light emitting diodes are widely in use now. According to the packaging method of the light emitting diodes, there are through-hold light emitting diodes, surface-mounted device light emitting diodes, and flip-chip light emitting diodes, etc.
Referring to
FIG. 1
, it shows that a cross-sectional view of a conventional light-emitting cell fixed on a die carrier. The light-emitting cell includes mainly an epitaxial structure
10
formed on a substrate
20
, and the epitaxial structure
10
consists of at least an n-type semiconductor layer, an active layer, and a p-type semiconductor layer. Due to the progress of the process technologies, in order to increase the light emitting intensity of the light emitting diode, instead of the substrate
20
a transparent substrate is utilized after the epitaxial structure
10
is formed. Thus, the emitting light from the light emitting diode is not absorbed by the opaque substrate, and the light-emitting cell becomes a cell that can emit light in forward, backward and sideward directions, so that the light emitting efficiency of the light-emitting cell is increased. In theory, the light emitting and detecting device, which uses the transparent substrate, should be a high efficiency electro-optics device with the features of emitting and detecting light in forward, backward and sideward directions. However, since there is a limitation of the conventional packaging method, and the electrode on the transparent substrate is still formed by the conventional gilding or surfgold method, the efficiency of light emitting and detecting is only increased on the sidewalls of transparent substrate with the used of the transparent substrate. Therefore, the advantage of the device having the transparent substrate cannot be exerted completely.
As shown in
FIG. 1
, the die carrier
30
of the light-emitting cell is shown. A lead frame, a printed circuit board, or a header is usually used to be a carrier for packaging, and the die carrier
30
is bonded to the substrate
20
of the light-emitting cell to form the first electrode of the light-emitting cell. The cell-fixing surface
40
between the light-emitting cell and the die carrier
30
is fixed on the die carrier
30
by using silver paste, conductive paste, or eutectic bond. Then, a second electrode
50
upon the light-emitting cell is wire bonded to another point of the lead frame
35
. Thereafter, a power source is individually connected to the die carrier
30
and the lead frame
35
, so that the epitaxial structure
10
of the light-emitting cell emits light.
As shown in
FIG. 2
,
FIG. 2
is a cross-sectional view of a conventional light-emitting cell fixed on a die carrier, wherein the conventional light-emitting cell has a substrate made of insulating material. If the substrate
70
of the light-emitting cell is made of an insulating material, the process is the same as the one described above. The cell-fixing surface
90
between the light-emitting cell and the die carrier
80
is fixed on the die carrier
80
by using silver paste. Then, a first electrode
92
is wire bonded to the lead frame
85
and the second electrode
94
is wire bonded to the die carrier
80
, respectively. Finally, a power source is individually connected to the die carrier
80
and the lead frame
85
, and then the epitaxial structure
60
of the light-emitting cell emits light.
However, owing to the light-emitting cell bonded directly on the die carrier, the light generated from the light-emitting cell is absorbed by the conventional cell-fixing surface. Therefore, most of the light emitted through the transparent substrate is absorbed by the cell-fixing surface, although the transparent substrate is utilized to replace the opaque substrate. Thus, the light emitting efficiency is decreased, and the advantage, that the light can be emitted in forward and backward directions from the light-emitting cell with the use of the transparent substrate, cannot be fully performed.
SUMMARY OF THE INVENTION
In view of the background of the invention described above, for overcoming the disadvantage, that the light emitting efficiency of the light emitting diode is decreased because the light emitted from the light-emitting cell is absorbed by the cell-fixing surface after the light-emitting cell fixed on the die carrier, the present invention provides a structure and a method for forming an electro-optics device, and more particularly, for forming a high efficiency electro-optics device.
It is the primary object of the present invention to provide a structure and a method for forming a high efficiency electro-optics device. In the present invention, the cell-fixing surface area between the die carrier and the electro-optics cell is decreased, thereby increasing the light emitting and detecting regions of the electro-optics cell. In the meantime, according to the present invention, by using a newly-designed gilding pattern, the light shielding area of the backside of the electro-optics cell is further reduced. Therefore, the light emitting efficiency and the photo detecting sensitivity of the electro-optics device are also increased substantially, so that the electro-optics cell can perform with the maximum efficiency. More particularly, for a device having a transparent substrate, the structure provided by the present invention together with the newly-designed gilding pattern matching with the structure can let the device fully perform, thereby resolving the problem of the low device efficiency.
It is the secondary object of the present invention to provide a structure and a method for forming a high efficiency electro-optics device. With the present invention, a self-aligned bond can be achieved by utilizing the eutectic or the metal-melting method when the electro-optics cell is fixed on the cell-fixing surface. Thus, the accuracy for packaging the device is increased substantially, and the failure therefore is decreased.
In accordance with the aforementioned objects of the present invention, the present invention provides a structure of high efficiency electro-optics device, the structure consisting of: a cell-fixing surface defined on the convex portion of a convex die carrier; an electro-optics cell, located on the cell-fixing surface, the electro-optics cell having a first electrode electrically connected with the convex die carrier and a second electrode electrically connected with another lead frame.
In accordance with the aforementioned objects of this invention, the present invention provides a method for forming a high efficiency electro-optics device, comprising the following steps of: providing a convex die carrier with a convex portion defined as a cell-fixing surface; bonding an electro-optics device cell, which has a first electrode and a second electrode, on the cell-fixing surface; connecting the first electrode electrically with the convex portion of the convex die carrier; and connecting the second electrode electrically with a lead frame.
REFERENCES:
patent: 5574282 (1996-11-01), Walker et al.
patent: 5743006 (1998-04-01), Beratan
patent: 6025251 (2000-02-01), Jakowetz et al.
patent: 6465784 (2002-10-01), Kimata
patent: 6562637 (2003-05-01), Akram et al.
patent: 6562643 (2003-05-01), Chen
patent: 6573121 (2003-06-01), Yoneda et al.
Hsu Jung-Kuei
Lin Ming-Der
Tsai Chang-Da
Wang Kwang-Ru
Ben Loha
Opto Tech Corporation
Sughrue & Mion, PLLC
LandOfFree
Structure and method for forming a high efficiency... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Structure and method for forming a high efficiency..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Structure and method for forming a high efficiency... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3196166