JPS6180207A - Substrate for electrical and optical circuit element - Google Patents

Abstract

PURPOSE:To reduce the size and cost of a module by providing insertion holes meeting the shape and size of a light emitting element, photodetector and optical fibers for transmission to be mounted and connected to the terminal part of the optical waveguides embedded into a ceramic substrate. CONSTITUTION:A guide hole 2 for installation of the light emitting element, a guide hole 3 for installation of the photodetector and a face plate insertion hole 8-1 layer in diameter than said hole are provided to the ceramic substrate 1. A stainless steel screen is placed on the substrate 1 and Au and Ag-Pd paste is printed on the substrate to form wiring conductors 4 which are then calcined in a belt furnace. A face plate 6 is put into the hole 8-1 and the spacing is filled by an adhesive agent 7 and is heated, by which the circuit substrate is obtd. The light emitting element 11 and the photodetector 12 are then set in the guide holes 2, 3 by which the circuit connection is executed. The decrease in the optical coupling loss, the reduction in the size of the module, etc. are thus made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an electrical and optical element substrate, and more particularly to an electrical and optical circuit element substrate for a small and inexpensive optical transmission module.

[Background of the invention]

In recent years, the development of optical communication using optical fiber as a transmission route has been remarkable, and it has been applied to communication trunk lines, electric power, plants, office automation (OA), factory automation, local area networks (LAN), and even advanced information communication networks. Application to subscriber transmission systems in the (INS) plan is being considered.

In applying optical communications to these communications fields, it will be important in the future for the equipment and parts that make up the system to be inexpensive, to miniaturize modules, to simplify assembly, and to establish mass production technology.

The optical transmission module necessary for receiving and transmitting signals in optical communication mainly consists of an optical system circuit section that connects the light receiving and emitting elements and the transmission fiber, electrical elements such as ICs necessary for transmitting and receiving, and their electrical wiring circuit section. ing.

Conventionally, the above-mentioned two types of optical transmission modules have been completely different mounting systems, and they have been installed in separate spaces.

That is, optical components such as a light receiving/emitting element, a condensing lens, and a transmission fiber are arranged three-dimensionally to form an optical path, and ICs and the like are arranged two-dimensionally on a substrate.

For this reason, the module always required space to accommodate the two types of components mentioned above. This has been an obstacle to miniaturization of modules.

In addition, the optical system circuit unit that combines optical components to form an optical path is
This caused the module assembly work to be extremely inefficient. The reason for this is that there is a lot of adjustment work, such as aligning the optical axes of individual optical components, such as rod lenses, ball lenses, light receiving and emitting elements, and transmission fibers, and matching the focal length of the lenses.

Furthermore, when the optical system components are fixed (glued), the shrinkage effect of the adhesive as it dries causes the component spacing that matches the once adjusted optical axis and focal length to become misaligned, causing problems at the optical coupling section. It had the drawback of causing defects.

For these reasons, miniaturization of conventional optical transmission modules has been hindered, and improvements in mass productivity and product yield have been hindered. These factors have hindered the cost reduction of optical transmission modules (Japanese Unexamined Patent Publication No. 117114/1983).

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned drawbacks of the prior art and to provide a small and inexpensive electrical and optical circuit element substrate for an optical transmission module.

[Summary of the invention]

In the present invention, an optical waveguide is embedded in a ceramic substrate, and a substrate section located at the end of the waveguide is used for mounting and connecting the light receiving and emitting elements and the transmission fiber (optical fiber).
Use one that has an insertion hole (guide hole) that matches the shape and dimensions.

If such a guide hole is provided, the light receiving/emitting element and the fiber can be mounted extremely easily.

Furthermore, electrical wiring is provided on the ceramic substrate by a thick film or thin film method.

Preferred materials for forming the electrical and optical circuit element substrate of the present invention are shown in Table 1.

(The following is a blank space) -4= Note that the face plate, which is a waveguide material in the same table, usually refers to a plate made of an aggregate of fibers with a large aperture ratio.

For example, it is a plate made by bundling a large number of glass fibers with a core diameter of about 15 to 25 μm or less, fusing and fixing them with low melting point glass (which acts as a cladding), and cutting the bundles at right angles to the optical axis direction. By polishing both sides of the plate, it is possible to direct light (eg, a light spot or image) from one side to the other without scattering it.

Therefore, by embedding the face plate in the ceramic substrate, the optical transmission fiber and the light receiving/emitting element can be coupled through the ceramic substrate to form an optical path.

The waveguide material for this light is not limited to face plates.
Any material having a light waveguide function, such as a conventional Rondo lens, optical fiber, or ball lens, can be used (Table 2).

By embedding these waveguide materials in a ceramic substrate with electrical wiring and integrating the electrical and optical circuits, it becomes unnecessary to separately provide the space required for the optical coupling section. Therefore, the optical transmission module can be significantly downsized.

Furthermore, this eliminates the need to combine individual optical components, simplifying the assembly work of the optical system, and greatly reducing the number of parts and steps. Furthermore, the present invention has the advantage that components necessary for the optical transmission module can be mounted all at once on a single board.

(Margin below) [Embodiments of the invention] Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 First, an alumina-based ceramic substrate 1 was prepared with a light emitting element installation hole 2, a light receiving element installation hole 3, and a face plate insertion hole 8-1 having the shapes shown in FIGS. 1(a) and 1(b). was made using the casting method.

Next, place a stainless steel screen on this substrate 1, and
U and Ag--Pd based paste were printed to form the unfired wiring conductor 4 shown in FIG.

Here, the Au conductive paste is applied to the wire bonding wiring part of the transmitting electric element mounting part 13 and the receiving electronic element mounting part 14 shown in FIG. 2, and the Ag-Pd conductive paste is applied to the wiring part where the lead pin 5 is attached. Using.

The substrate printed in this way was heated to 850°C using a belt furnace.
A wiring board having a thick film wiring conductor as shown in FIG. 2 was obtained.

Next, turn over the ceramic substrate 1 of the wiring section, and
Place the face plate (waveguide material) 6 shown in the figure in the face plate insertion hole 8-1, and insert the bonding agent 7 made of glass frit hardened into a ring shape into the gap between this hole and the face plate 1-6. and filled it.

In this way, the face plate and the wired board coated with the ring-shaped bonding agent were heated to 500°C using a belt furnace.
The alumina substrate 1 and the face plate 1-6 were fused using a glass frit l- of bonding agent 7 to obtain an electrical and optical circuit board.

Next, the lead pins 5 shown in FIG. 2 were soldered to the eight pin-combined wires to form electrical signal output terminals.

After that, the light emitting element 1.1 and the light receiving element 1 shown in FIG.
2 was set in the guide hole 2 for installing a light emitting element and the guide hole 3 for installing a light receiving element on the substrate, and circuit connection was performed by the face-to-face bonding method. In addition, the chip capacitor was fixed in the same manner at the chip capacitor installation position w9 in FIG.

Next, the transmitting IC [5] and the receiving TC]6 necessary for driving the light emitting element and receiving and transmitting optical signals shown in FIG. 14, and these electric circuits were connected by wire bonding.

Next, a nylon fiber insertion guide ring 10 was inserted into the remaining part of the face plate insertion hole 8-1 shown in FIG. 3 to form a transmission fiber guide 68-2.

The thus obtained optical transmission module board with elements mounted thereon is sealed with a sealing resin 17 as shown in FIGS. 4(a) and 4(b), and the transmission fiber 18 is inserted into the fiber guide 68-2. A two-way optical transmission module was obtained.

The characteristics of the bidirectional optical transmission module obtained above and the characteristics regarding module assembly were as follows.

(1) Optical coupling loss = 8 to 10 dB (2) Miniaturization of module: 175 compared to conventional (3) Reduction in number of parts: 1/2 compared to conventional (4) Reduction in number of steps: 1. /3 (5) Reduction of defective rate: Conventional 174 11-Example 2 Insertion of waveguide material into an alumina substrate (Fig. 2) provided with a thick film wiring conductor made in the same manner as in Example 1 68- A ring-shaped hardened glass frit was inserted into 1, and a ball lens was inserted inside the ring-shaped glass frit.

Next, using a belt furnace, the substrate and the ball lens were fused together by heating to 500° C. with glass frit 1 to obtain an electrical and optical circuit element substrate.

Thereafter, a light emitting/receiving element, a transmitting/receiving IC 5, and a chip capacitor were mounted in the same manner as in Example 1, and a transmission fiber was connected to obtain a bidirectional optical transmission module.

The characteristics of the bidirectional module thus obtained and the characteristics regarding module assembly were as follows.

(1) Optical coupling loss: 5 to 7 dB (2) Miniaturization of module: 175 compared to conventional (3) Reduction in number of parts: 1/2 compared to conventional (4) Reduction in number of steps: 1/3 compared to conventional (5 ) Reduction in defective rate: Conventional 173 Example 3 Glass-ceramic substrates having the shapes shown in FIGS. 1(a) and 1(b) were made by a green sheet lamination method.

Next, a hardened ring-shaped glass frit was placed in the waveguide insertion hole 8-1 of the substrate, and a rod lens was inserted inside the ring-shaped glass frit.

Next, in the same manner as in Example 1, the rod lens and the substrate were fused together using a glass frit, and the substrate was fired.

Next, the surface of this substrate on the wiring side was polished and then cleaned with an organic solvent.

A thin film wiring conductor shown in FIG. 2 was formed on this cleaned substrate by a thin film method. Here, the wiring material was made of three layers of Cr-N1-Au, and the wiring shape was formed by the stainless steel mask method.

Using the electric and optical circuit element substrate obtained in this way,
A light emitting/receiving element, a transmitting/receiving IC, and a chip capacitor transmission fiber were mounted and connected in the same manner as in Example 1 to obtain a bidirectional optical transmission module.

The characteristics of the bidirectional optical transmission module and module assembly using this method were as follows.

(1) Optical coupling loss = 3 to 5 dB (2) Miniaturization of module: 115 compared to conventional (3) Reduction in number of parts: 1/2 compared to conventional (4) Reduction in number of steps: 1/2 compared to conventional (5 ) Reduction in defective rate: 172 compared to conventional [Effects of the invention] As described above, the electrical and optical circuit element board of the present invention has excellent performance as shown in (1) to (3) below. .

(1) Downsizing module dimensions, (2) Improving module assembly productivity by reducing module assembly man-hours, assembly time, and number of assembled parts, and lowering module costs; (3) Optical devices and transmission fibers. Relax installation tolerances and maintain and improve light coupling efficiency.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the base board of the electrical and optical circuit element board of the present invention, FIG. 2 is a diagram showing the state in which electrical wiring and terminals are provided on the board of FIG. 1, and FIG. FIG. 4 is a diagram showing a state in which a face plate is embedded in the substrate shown in the figure, and FIG. 4 is a diagram showing a state in which a bidirectional optical transmission module is assembled using the board shown in FIG. DESCRIPTION OF SYMBOLS 1... Ceramic substrate, 2... Hole for installing a light emitting element, 3... Hole for installing a light receiving element, 4... Wiring conductor, 5...
...Electrical terminal lead pin, 6...Face plate,
7... Bonding material, 8-1... Face plate insertion hole, 8-2... Fiber insertion hole, 9... Chip capacitor installation position, 10... Fiber insertion guide ring,
11... Light emitting element, 12... Light receiving element, 13...
Transmitting electric element mounting part, 14... Light receiving electric element mounting part, 15... Transmitting IC 116... Receiving IC 11
7... Mold, 18... Optical transmission fiber.

Claims (1)

[Claims] 1. A ceramic substrate provided with at least two through holes of varying diameters, and a waveguide material fixed in the large diameter holes of these through holes. An electrical and optical circuit element substrate, in which optical fibers are inserted into small-diameter holes, and these optical fibers are optically coupled to the waveguide material. 2. The electric and optical circuit element board according to claim 1, wherein the waveguide material is a face plate, a rod lens, or a ball lens. 3. A ceramic substrate provided with at least two through holes with varying diameters, and a waveguide material fixed in the large diameter holes of these through holes, and a waveguide material fixed in the small diameter holes of these through holes. An electrical and optical circuit element board, wherein optical fibers are inserted into the board, the optical fibers are optically coupled to the waveguide material, and a wiring conductor is provided on at least one surface of the board. 4. The electric and optical circuit element board according to claim 3, wherein the waveguide material is a face plate, a rod lens, or a ball lens. 5. The electrical and optical circuit element substrate according to claim 3, wherein the wiring conductor is a thick film wiring conductor or a thin film wiring conductor.