Optical waveguides – With disengagable mechanical connector – Optical fiber to a nonfiber optical device connector
Reexamination Certificate
1998-06-12
2001-07-10
Bovernick, Rodney (Department: 2874)
Optical waveguides
With disengagable mechanical connector
Optical fiber to a nonfiber optical device connector
C385S059000, C385S075000, C385S092000
Reexamination Certificate
active
06257771
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an electro-optical hybrid wiring board suitable for use to handle both optical and electrical signals, and a method for making same.
There have evolved examples in which a portion of an apparatus is constructed of optical circuits for the purpose of increasing the response speed of the apparatus, eliminating the interference between the circuits, or the like.
An example of the construction of the prior art electro-optical hybrid apparatus is illustrated in
FIG. 1
in which the reference numeral
11
indicates a mother board while
12
are daughter boards mounted to the major surface of the mother board
11
in an orientation perpendicular to the plane of the mother board. The daughter boards
12
are electrically connected with the mother board
11
by means of electrical connectors
13
mounted to the major surface of the mother board
11
.
On the other hand, the interconnections between the daughter boards
12
for optical signals are separately established by optical communication modules
15
and optical fibers
16
.
In the conventional electro-optical hybrid apparatus, while the electrical interconnections between the daughter boards are collectively effected by the electrical connectors
13
and mother board
11
, optical signal interconnections must be made separately for each route by means of the optical communication modules
15
and optical fibers
16
. The optical communication modules
15
and optical fibers
16
are configured to be detachably connected together by optical connectors
17
. However, for a large scale apparatus such as an IC tester, a tremendous amount of labor is required for the connecting and disconnecting operations because of the great number of optical signal paths which may amount to as many as several thousands. Although there are available optical connectors capable of connecting and disconnecting a plurality of optical fibers at one time, such configuration of connection could not cope with an enormous number of optical signal paths as many as several thousands. In addition, misconnections are likely to occur, and undesirably much labor is required for the assembly.
Wim Delbare and Louis Vandam deals with the configuration of connection for numerous glass optical fibers embedded in the surface layer of an electro-optical board in their “ELECTRO-OPTICAL BOARD TECHNOLOGY BASED ON DISCRETE WIRING”, Proc. International Electronic Packaging Conf., pp. 604-618, 1991. According to this connecting method, a supporting glass fiber (or copper wire) is laid on a wiring board to extend in a straight line and a plurality of glass optical fibers are arrayed so as to cross perpendicularly over the supporting glass fiber whereby the optical fibers will have bent portions protruding upwardly. These fibers are then embedded in a filler layer to form an electro-optical board (daughter board ). The upper surface of the filler layer is shaved to expose the raised bent portions of the fibers, which raised portions are ground to form optical coupling faces, against which optical couplers disposed in a mother board are opposed to optically connect the optical fibers of the electro-optical board with those of the wiring board (mother board) oriented perpendicularly to the electro-optical board. This connecting approach allows for collectively interconnecting numerous optical fibers between a mother board and daughter boards, but is involved with difficulties in grinding many arrayed bent portions of optical fibers by the same depth to the cores of the optical fibers and consequently suffers from the drawback of significant variation in the optical coupling characteristics.
SUMMARY OF THE INVENTION
Accordingly, it is an object of this invention to provide an electro-optical hybrid wiring board which permits collective connection and disconnection of optical signal paths with reduced variation in the optical coupling characteristics as well as electrical circuits and which is easy to manufacture, and a method for making same.
According to this invention, an optical fiber-embedded layer having optical fibers embedded therein is provided as one layer of a multiple-layered electrical wiring board. A plurality of end faces of the optical fibers laid in that layer are exposed at the lateral end of the insulating substrate of the wiring board to form a lateral end coupling to allow for optical coupling at the lateral end in a direction parallel to the plane of the substrate. The other end faces of the optical fibers laid in the optical fiber-embedded layer are also exposed to provide a surface coupling to allow for optically coupling the other end faces in a direction orthogonal to the plane of the insulating substrate. It will thus be appreciated that by virtue of the combination of the lateral end coupling and the surface coupling, this invention provides for both electrical and optical direct connections between boards positioned orthogonally with each other such as in the relation between the mother board and the daughter boards.
The electro-optical hybrid wiring board according to this invention comprises:
an insulating substrate having an adhesive layer formed on one side surface thereof;
a plurality of optical fibers first end portions of which are arranged on the insulating substrate and laid in a predetermined pattern over the surface of the insulating substrate and attached to the adhesive layer;
a filler layer applied in a thickness sufficient to fill up undulations of the surface defined by the array of the optical fibers;
a covering sheet applied to the filler layer;
window means formed through the filler layer and the covering sheet to expose the first end portions of the optical fibers;
reflecting means for reflecting light exiting from the first end portions of the optical fibers perpendicularly to the plane of the insulating substrate within the window means and directing the light out of the covering sheet through the window means, and/or reflecting light entered through the window means from outside of the covering sheet perpendicularly to the plane of the substrate and directing the light at a right angle into the first end portions of the optical fibers; and
an electrical wiring sheet laminated to the other side surface of the insulating substrate.
A method for manufacturing an electro-optical hybrid wiring board according to this invention comprises the steps of:
(a) applying adhesive to one side surface of an insulating substrate to form an adhesive layer;
(b) laying a plurality of optical fibers in a predetermined pattern over the surface of the adhesive layer while attaching the fibers to the adhesive layer, and applying a filler material in a thickness sufficient to encapsulate the optical fibers; and
(c) applying a covering sheet to the top surface of the filler material.
The electro-optical hybrid wiring board according to this invention provides for coupling optical signals between boards positioned in orthogonal relation with each other whereby the variation in the positional alignment may be minimized.
The invention also provides a method for easily manufacturing such electro-optical hybrid wiring board with little variation in the optical coupling characteristics.
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Advantest Corporation
Bovernick Rodney
Gallagher & Lathrop
Lathrop David N.
Stahl Michael
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