Optical waveguides – Integrated optical circuit
Reexamination Certificate
2000-03-30
2002-08-20
Sanghavi, Hemang (Department: 2874)
Optical waveguides
Integrated optical circuit
C385S049000, C385S088000, C385S089000
Reexamination Certificate
active
06438281
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 11-088569, filed Mar. 30, 1999; and No. 11-096060, filed Apr. 2, 1999, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates to an optical wiring layer through which light propagates, an optoelectric wiring substrate comprising the optical wiring layer and a substrate having an electric wiring, a mounted substrate in which an optical part or the like is mounted on the optoelectric wiring substrate, and methods for manufacturing each of these structures.
In the field of electric elements such as semiconductor large-scale integrated circuits (LSI), the degree of integration of transistors has been increasing. Some semiconductor large-scale integrated circuits Among these LSIs are those which operate at so high a clock frequency as 1 GHz.
To mount highly integrated electric elements on an electric wiring substrate, packages such as BGAs (Ball Grid Arrays) and CSPs (Chip Size Packages) have been developed and put to practical use.
In general, the inter-element signal speed outside an electric element increases linearly with the clock frequency inside the electric element. The increase in inter-element signal speed induces noise such as reflection arising from the inappropriate shape of an electric wiring joining elements together, or cross talk. Another problem may occur that this increase causes an increased amount of electromagnetic waves to be generated from the electric wiring to adversely affect the surroundings. Thus, in constructing systems, the signal speed between electric elements is diminished enough to prevent these problems. As a result, highly integrated electric elements cannot fully provide their functions.
In order to solve these problems, the following methods have been contemplated: Part of an electric wiring on an electric wiring substrate is replaced with an optical wiring comprised of optical fibers so that optical signals are used instead of electric signals. This is because optical signals do not cause noise or electromagnetic waves.
An example of this method if disclosed in Japanese Laid-Open Patent Publication (Kokai) No. 9-236731. This is a method for forming optical waveguides on an electric wiring substrate. Specifically, optical waveguides are directly formed on a ceramic multilayer wiring substrate (in the order of a clad layer, a core pattern, and a clad layer).
Multiple layers of electric wirings, however, are formed on a surface of the electric wiring substrate, which acts as an under layer of the optical wiring layer. This electric wiring forms very large recesses and projections. Thus, disadvantageously, when the optical waveguides are formed on the electric wiring substrate, the propagation loss of optical waves increases.
BRIEF SUMMARY OF THE INVENTION
The present invention is provided in view of these circumstances, and it is an object thereof to provide an optical wiring layer, an optoelectric wiring substrate, a mounted substrate, and methods for manufacturing these structures wherein the propagation loss of optical signals is small and wherein high-density mounting and size reduction can be achieved.
The present invention is an optoelectric substrate comprising a substrate having an electric wiring and an optical wiring layer laminated on the substrate, the optical wiring layer comprising: a core through which light propagates; a clad for holding the core; a mirror for reflecting light propagating through the core; first conductive installation means formed on a surface of the optical wiring layer for installing light-receiving means for receiving light reflected by the mirror or light-emitting means for emitting light toward the mirror; and connection means for electrically connecting the first conductive installation means to the electric wiring.
According to this optoelectric wiring substrate, an optical wiring layer is laminated on a substrate having an electric wiring, in addition, conductive installation means, which install an optical part on the optical wiring layer, are provided. The optical part installed on the conductive installation means is electrically connected to the electric wiring.
Accordingly, with this configuration, the optical wiring layer is laminated on the substrate with the electric wiring. As a result, high-density mounting and size reduction can be achieved.
Another optoelectric wiring substrates according to present invention are as follows:
(1) The present invention is An optoelectric substrate comprising a substrate having an electric wiring and an optical wiring layer laminated on the substrate, the optical wiring layer comprising: a core through which light propagates; a clad for holding the core; a mirror for reflecting light propagating through the core; second conductive installation means formed on a surface of the optical wiring layer for installing an electric part; and connection means for electrically connecting the second conductive installation means to the electric wiring.
According to this optoelectric wiring substrate, an optical wiring layer is laminated on a substrate having an electric wiring, in addition, conductive installation means, which install an electric part on the optical wiring layer, are provided. The electric part installed on the conductive installation means is electrically connected to the electric wiring.
Accordingly, with this configuration, high-density mounting and size reduction can be achieved.
(2) The present invention is an optoelectric substrate comprising a substrate having an electric wiring and an optical wiring layer laminated on the substrate, the optical wiring layer comprising: a core through which light propagates; a clad for holding the core a mirror for reflecting light propagating through the core; first conductive installation means formed on a surface of the optical wiring layer for installing light-receiving means for receiving light reflected by the mirror or light-emitting means for emitting light toward the mirror; second conductive installation means formed on the optical wiring layer surface for installing an electric part; connection means for each of the conductive installation means to the electric wiring.
According to this optoelectric wiring substrate, an optical wiring layer is laminated on a substrate having an electric wiring, in addition, first conductive installation means for installing an optical part and second conductive installation means for installing an electric part, are provided. The optical part and the electric part installed on each of the conductive installation means are electrically connected to the electric wiring.
Accordingly, with this configuration, high-density mounting and size reduction can be achieved.
(3) The present invention is an optoelectric substrate comprising a substrate having an electric wiring and an optical wiring layer laminated on the substrate, the optical wiring layer comprising a first clad; a first core formed on the first clad through which light propagates; a mirror for reflecting light propagating through the first core; a second core formed on the first clad using a material identical to that of the first core; first conductive installation means laminated on the second core for installing light-receiving means for receiving light reflected by the mirror or light-emitting means for emitting light toward the mirror; connection means for electrically connecting the first conductive installation means to the electric wiring, and a second clad for holding at least one of the first clad, the first core, the mirror, the second core, and the connection means.
According to this optoelectric wiring substrate, an optical wiring layer is laminated on a substrate having an electric wiring, in addition, conductive installation means, which install an optical part on the optical wiring layer, are provided. The optical part installed on the conductive installation means is electrically
Hirayama Shigeru
Kumai Koichi
Minato Takao
Ode Masayuki
Tsukamoto Takehito
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