Active solid-state devices (e.g. – transistors – solid-state diode – Incoherent light emitter structure – With housing or contact structure
Reexamination Certificate
2002-07-17
2003-12-30
Crane, Sara (Department: 2811)
Active solid-state devices (e.g., transistors, solid-state diode
Incoherent light emitter structure
With housing or contact structure
C257S098000, C257S100000
Reexamination Certificate
active
06670648
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor light-emitting device, and more particularly to a semiconductor light-emitting device having a reflective case provided on a insulating substrate.
2. Description of the Prior Art
Semiconductor light-emitting elements, such as light-emitting diode elements, often have a reflective case provided around them to permit the light emitted from the semiconductor light-emitting elements to be directed in a particular direction.
FIG. 10
is a side sectional view showing an example of a conventional semiconductor light-emitting device having a reflective case
5
provided on an insulating substrate
1
. In the conventional semiconductor light-emitting device, the space inside the reflective case
5
is sealed with a translucent resin
6
, of which a typical example is a thermosetting resin such as epoxy resin. Thus, the translucent resin
6
is first poured into the reflective case
5
, and is then cured by being heated to a temperature a few of tens of degrees over 100° C.
However, the translucent resin
6
usually does not adhere well to the material of reflective case
5
, and, when the translucent resin
6
is cured by application of heat in a reflow furnace or the like, the translucent resin
6
often comes off the reflective case
5
, producing a defective device.
Moreover, in general, the light emitted from a light-emitting element
3
through the corners thereof is weaker than the light emitted therefrom through the sides thereof, and thus, as shown in a luminous intensity curve diagram in
FIG. 11
, the device, when viewed in a plan view, emits light with uneven intensity in different directions.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a light-emitting device in which, even if the space inside a reflective case is sealed with a translucent resin that does not adhere well to the material of the reflective case, the translucent resin does not come off the reflective case after being cured.
Another object of the present invention is to provide a light-emitting device that emits light with more even intensity in all directions.
To achieve the above object, according to the present invention, a semiconductor light-emitting device has a semiconductor light-emitting element mounted on an electrode formed on a surface of an insulating substrate, and has a reflective case provided on the insulating substrate so as to reflect the light from the semiconductor light-emitting element, with the space inside the reflective case sealed with a translucent resin. Moreover, the reflective case has a grained portion formed over at least part of the surface thereof over which its makes contact with the translucent resin. Structured in this way, the semiconductor light-emitting device according to the invention effectively prevents the translucent resin from coming off the reflective case.
To enhance the adherence between the translucent resin and the reflective case and simultaneously enable the device to emit light with more even intensity in all directions, it is preferable that the grained portion be formed at least in the portions of the reflective case that face the side surfaces of the semiconductor light-emitting element.
To more securely prevent the translucent resin from coming off the reflective case, it is preferable that the grained portion be formed with a depression-to-projection height difference of 12 &mgr;m or more, or with a projection-to-projection pitch of 20 &mgr;m or less. As shown in
FIG. 5
, in the present invention, the depression-to-projection height difference denotes the ten-point average surface roughness, and the projection-to-projection pitch denotes the distance from one projection to the next.
For higher productivity of the device or out of other considerations, the insulating substrate and the reflective case may be formed integrally
A preferred material of the reflective case is a liquid crystal polymer for its heat resistance and low thermal expansion, and a preferred example of the translucent resin is epoxy resin for its translucence.
REFERENCES:
patent: 3883772 (1975-05-01), Wako et al.
patent: 6274890 (2001-08-01), Oshio et al.
Isokawa Shinji
Okazaki Tadahiro
Crane Sara
Morgan & Lewis & Bockius, LLP
Rohm & Co., Ltd.
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