JPH11160585A - Optical element mounting substrate and optical module using the same - Google Patents

Abstract

(57) Abstract: An optical element mounting substrate, which can precisely and reproducibly set a distance between an optical element and an optical fiber, and which can extremely easily mount an optical element. To provide an optical module using the same. SOLUTION: A plate-like body 21 provided with a light guide path 22 is provided on a substrate 31, and an optical element 27 for emitting or receiving light is mounted on one main surface side of the plate-like body 21 and on another main surface side. Optical element 2
An optical waveguide body 33 that optically couples with the optical waveguide 7 is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element mounting board in which an optical semiconductor element (optical element) as a light emitting element or a light receiving element is mounted on a substrate, and an optical module using the same.

[0002]

2. Description of the Related Art In recent years, application of optical communication to homes and offices has been rapidly advanced. Such widespread application development of optical communication will hold the key to realizing an information society. A technology for producing an optical element mounted module, which is the center of the optical communication technology, with high precision and with good yield at low cost is indispensable for the development of optical communication.

Conventionally, there has been known an optical module in which an optical element such as a PD (photodiode) for performing optical coupling with an optical fiber in a plane is aligned with high accuracy, and the configuration is as shown in FIG.

That is, the substrate 11 having the V-shaped groove 12 formed thereon
An optical fiber 13 is mounted and fixed thereon, and an optical element 15 as a light receiving element is mounted on a plate-shaped subcarrier 14 fixed on the substrate 11, and the light receiving surface of the optical element 15 is an end face of the optical fiber 13. It was oriented to the 13a side.

[0005]

However, in the above-described optical module J1, the fixed position of the subcarrier 14 or the fixed position of the optical fiber 13 is determined by visually recognizing the distance. It was difficult to control the distance of No. 13 precisely and with good reproducibility.

[0006] Further, an optical element 15 is placed on the subcarrier 14.
In particular, since the pad for wire bonding existing on the light receiving surface side of the PD chip has a diameter of about several tens of μm and is very small, wire bonding is very difficult.

Therefore, according to the present invention, the distance between the optical element and the optical fiber can be set precisely and with good reproducibility.
Moreover, it is an object of the present invention to provide an optical element mounting board which can extremely easily mount an optical element and an optical module using the same.

[0008]

In order to achieve the above object, an optical element mounting board according to the present invention is provided with a plate having a light guide path on a substrate, and one main surface of the plate. An optical element for emitting or receiving light is mounted on the side, and an optical waveguide body for optically coupling with the optical element is provided on the other main surface side.

Further, the light guide path of the plate-like body is characterized in that it is constituted by a through hole or a transparent body.

Further, the present invention is characterized in that the substrate and the plate-like body are made of the same material.

[0011] Further, the invention is characterized in that both main surfaces of the plate-shaped body are non-parallel.

The optical module according to the present invention is characterized in that an optical waveguide for optically coupling with an optical element is disposed on the other main surface of the plate-like body on the optical element mounting board.

Conventionally, the surface emitting type or surface receiving type optical element has the opposite side of the coupling surface fixed to the subcarrier. However, in the present invention, the subcarrier (for example, a through-hole provided in the light emitting or light receiving portion) is provided. It is characterized in that the light-emitting and light-receiving surfaces are fixed on a plate-like body).

The plate-like body may be provided with a wiring pattern for performing electrical wiring when the optical element is fixed, and is electrically connected to an electrode pad on the light emitting / receiving surface of the optical element. Taken. When the optical element is mounted on the plate-shaped body, the electrical connection is performed by, for example, a flip-chip bonding method using a solder bump or the like, and the carrier mounting and the electrical connection can be performed simultaneously.

Further, when the wiring pattern is formed on the plate-like body as described above, the wiring pattern on the substrate can be electrically connected to the wiring pattern on the substrate by soldering on the substrate. There is an advantage that the necessity of the optical module is eliminated, and there is an effect that the assembly of the optical module is greatly simplified.

Further, the distance between the optical fiber and the light receiving / emitting surface of the light receiving / emitting element can be accurately determined by abutting the optical fiber on the plate-like body, so that accurate and reproducible mounting is possible.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. Here, a photodiode (hereinafter, referred to as PD) using gallium nitride, amorphous silicon, or the like will be mainly described as an example of a surface-emitting light-receiving optical element. LED) and various surface emitting semiconductor lasers can employ the same method.

FIG. 2 shows an optical element mounting subcarrier S of the present invention.
1 shows an exploded perspective view of FIG. As shown in this figure, a through hole 22 which is a light guide path having ends on both main surfaces is formed in a subcarrier 21 which is a plate-like body. The opening of the through-hole 22 is formed in the light receiving portion 27 of the PD chip 27 to be mounted.
It is almost the same as c. Further, on one main surface side of the subcarrier 21, a wiring 23 is provided at a position corresponding to the electrode pad 27a of the PD chip 27.

As a material for forming the subcarrier 21, a ceramic mold, a laminated ceramic wiring board, plastic, glass or the like can be used, but is not particularly limited. Further, the light guide path provided in the subcarrier 21 does not need to be a through hole, and can be used as the subcarrier of the present invention without any problem as long as it does not block the light receiving surface. In addition, the wiring method is not limited to printing, lamination firing (lamination ceramic substrate), and the like.

On one main surface of the subcarrier 21, a wiring pattern 24 for connecting the back electrode 27b of the PD chip 27 and the wire 23 is also provided. At this time, the wirings 23 and 24 on the subcarrier 21 are routed to the bottom surface of the subcarrier 21. The electrode pads 27a of the PD chip 27 and the wirings 23 on the subcarrier 21 are flip-chip mounted face down using solder bumps.
After this flip chip mounting, the PD chip 27
Is connected to the wiring 24 on the subcarrier 21 by wire bonding.

As described above, the other main surface of the subcarrier 21 on which the PD chip 27 is mounted as shown in FIG.
The optical fiber 13 which is an optical waveguide placed on the groove 32
And the bottom surface portion is fixed on a concave portion 34 formed in a substrate 31 made of silicon or the like, and the optical fiber 13 is provided on the optical element mounting substrate to complete the optical module M1. Here, the bottom portion of the subcarrier 21 is the substrate 3
One of the recesses 34 is fixed by a suitable adhesive member such as solder. Here, the configuration excluding the optical fiber 13 is referred to as an optical element mounting board.

As described above, the optical element mounting subcarrier according to the present invention has the subcarrier with the through hole formed on the light receiving surface (optical function surface) side of the optical element. And the distance between the optical fibers can be precisely controlled by abutting the optical fibers. Further, since the light receiving element is mounted face-down so as not to block the light receiving surface on the subcarrier, it is possible to hit the subcarrier. Also, since wiring patterns are formed on the subcarriers and the flip-chip bonding technique can be used to mount the subcarriers on the substrate, the time and effort of wire bonding can be reduced. Also, by making the size of the through hole of the subcarrier substantially the same as or smaller than the light receiving surface of the optical element, it is possible to suppress optical coupling outside the light receiving surface of the optical element. It can be used with good performance. Further, by making the inner wall of the through hole dark or rough, the reflected light from the PD chip can be prevented from returning to the optical fiber. In addition, a transparent material may be filled in the through hole, whereby local sealing can be performed on the subcarrier.

Next, another embodiment of the present invention will be described in detail. [Modification 1] FIG. 4A is a perspective view showing a modification of the subcarrier of the present invention. (B) is a perspective view of the optical element. The subcarrier 41 has a through hole 4 having the same area as or smaller than the light receiving surface of the PD chip 47 to be mounted.
2 are provided. A carrier electrode pad 43 is provided on one main surface 49 of the subcarrier 41 corresponding to the surface electrode 48 of the PD chip 47, and the carrier electrode pad 43 is patterned to the bottom surface of the subcarrier 41. The chip mounting surface of the subcarrier 41 is P
Designed slightly larger than the entire surface of D chip 47, PD
PD is provided on a part of the subcarrier 41 not facing the chip 47.
An electrode pad 44 for wire bonding from the back electrode of the chip 47 is patterned down to the bottom surface of the carrier similarly to the carrier electrode pad 43.

A PD chip 47 is integrated with the subcarrier 41 by face-down pump bonding.
7 and the electrode pad 44 of the subcarrier 41 are connected by wire bonding. The sub-assembly of the sub-carrier 41 and the PD chip 47 manufactured in this way uses the bottom electrodes of the electrode pads 43 and 44 to perform electrical connection and fixation by bump bonding with the electrode pad on a separately manufactured platform. Also, the thickness 4 of the subcarrier 41
5 is designed to be a value determined from the tolerance in the optical axis direction with the optical fiber coupled to the PD chip 47, and is accurately positioned by abutting the fiber end face against the carrier surface.

With this configuration, the distance between the PD chip 47 and the end face of the optical fiber can be accurately determined. In addition, the electrical connection and fixing of the subassembly on the platform (the substrate 31 in FIG. 3) can be performed collectively, which simplifies the process and improves mass productivity. In addition, since the solder bump is fixed on the platform, self-alignment of the electrode pattern on the platform and the sub-assembly can be performed by soldering, and the steps such as positioning can be omitted.

[Modification 2] FIG. 5 is a perspective view showing another modification of the subcarrier of the present invention. As shown in FIG.
An electrode pad 52 is formed at a position corresponding to the electrode pad on the light receiving surface of the mounted PD chip so as to extend to the bottom surface of the subcarrier 51. The PD of the electrode pad 52
On the same surface as the mounting surface, an electrode 53 for wire bonding from the back electrode of the PD is formed up to the bottom surface of the subcarrier similarly to the electrode pad 52. Subcarrier 51 is PD
The height is such that the light receiving surface is not obstructed when the chip is mounted. After the PD chip is mounted on the subcarrier surface 55, the optical fiber is abutted against a surface 56 opposite to the mounting surface, so that the subcarrier thickness is reduced. The optical fiber is aligned in the optical axis direction controlled by 57. With such a structure, it is not necessary to form the through-hole as shown in the first modification, and it is possible to form a subcarrier having excellent mass productivity.

[Modification 3] FIG. 6 is a perspective view showing still another modification of the subcarrier of the present invention. In FIG. 6, the carrier height 54 of the subcarrier 51 shown in Modification 2 is slightly increased, and the depression 62 is formed so as not to block the light receiving surface, thereby increasing the area of the electrode pad 63 for wire bonding. When the PD chip is mounted on the subcarrier 61, wire bonding is facilitated, and defects during mounting can be reduced. In the figure, 64
Is an electrode pad connected to the light receiving surface side of the PD chip.

[Modification 4] FIG. 7A is a perspective view showing still another modification of the subcarrier of the present invention.
(B) shows an optical fiber 89 and an optical element 8 in the subcarrier 81.
FIG. 8 is a top view for explaining a state in which 8 are combined. Modification 2
A through-hole 84 is formed in the subcarrier 81 on which the electrode pads 82 and 83 similar to those shown in FIG. PD chip 8
The mounting surface 85 of No. 8 and the abutting surface 86 of the optical fiber have an angle of several degrees to several tens degrees. With such a design, reflected light from the light receiving surface of the PD chip 88 can be prevented from returning to the optical fiber 89, and reflected light that is extremely problematic in optical communication can be avoided. Here, in order to effectively prevent reflected light, the angle 87 is desirably 1 ° or more, and more preferably 1 ° to 10 °.

[Modification 5] FIG. 8A is a perspective view showing still another modification of the subcarrier of the present invention.
(B) shows an optical fiber 99 and an optical element 9 in the subcarrier 91.
FIG. 8 is a side view in which 8 is combined. The angle between the fiber abutting surface and the PD mounting surface shown in Modification 4 can be vertically set as shown in FIG. At this time, there is an advantage that the stability of the carrier at the time of mounting is increased by widening the bottom surface of the carrier. In the figure, 94 is a light guide path, and 92 and 93 are electrode pads.

[Modification 6] FIG. 9 is a cross sectional view showing a state in which an optical fiber 109 and an optical element 108 are optically coupled to a subcarrier 101.

As described above, for example, the depression 102 having a diameter substantially equal to or slightly larger than the diameter of the optical fiber is formed on the fiber abutting surface of the subcarrier shown in the first modification. By fitting the optical fiber 109 into the recess 102, it is possible to easily perform alignment in a direction perpendicular to the optical axis of the optical fiber 109. In the figure, 104
Is a light guide path.

[Modification 7] FIG.
FIG. 3 is a cross-sectional view of an optical fiber 111 and an optical element 118 optically coupled to each other.

As described above, the V-groove 111 for holding the fiber is formed on the fiber mounting side of the subcarrier shown in the first modification. When mounting the optical fiber, the fiber connection portion can be stably held by fixing the fiber with the V-groove 111. In the drawing, reference numeral 114 denotes a light guide path.

[Modification 8] FIG. 11 shows an optical element mounting subcarrier S2 in which an optical element is mounted on the subcarrier of the present invention.
It is a perspective view of.

A through hole 122 and an electric connection wiring 123 are routed through the subcarrier 121. The wiring 123 is routed to the bottom surface of the subcarrier 121 so that electrical contact can be made on the platform. Also,
The IC chip 124 such as a preamplifier required for driving the PD chip 128 is also mounted on the upper surface of the subcarrier 121. With such a structure, not only positioning in the optical axis direction but also mounting of a preamplifier can be performed at a short distance from the PD chip 128, so that a PD chip or IC suitable for high-speed communication can be mounted.

[Modification 9] FIG. 12 is a perspective view showing a modification of the subcarrier of the present invention. Subcarrier 131
At least a region serving as a light guide path is formed of a material such as glass that transmits light (particularly, light of 1.3 to 1.5 μm used in optical communication).
32 and 133 are formed up to the bottom surface. By doing so, the through-holes required in the first embodiment are not required, and the mass productivity of subcarriers is improved. 138 is a PD chip. In the case of this modified example, when a pin-type thin film optical sensor made of amorphous Si silicon or the like is used as the PD, it is very preferable that a film can be easily formed on a glass substrate or the like.

In this embodiment, for example, the wiring may be constituted by a transparent electrode such as ITO, and the constituent members such as a substrate, a plate, a light guide, an optical element and an optical waveguide, and their aspects, etc. In the above, the present invention can be appropriately modified and implemented without departing from the scope of the present invention.

[0038]

According to the present invention described above, an excellent optical element capable of easily positioning an optical fiber and an optical element performing surface light emission or surface light reception at an optimum distance with high accuracy and reproducibility. A mounting substrate and an optical module can be provided.

[Brief description of the drawings]

FIG. 1 is an overall schematic perspective view illustrating a conventional optical module.

FIG. 2 is a perspective view illustrating an optical element mounting subcarrier according to the present invention.

FIG. 3 is an overall schematic perspective view illustrating an optical module according to the present invention.

FIG. 4A is a perspective view of a subcarrier according to the present invention, and FIG. 4B is a perspective view of an optical element.

FIG. 5 is a perspective view showing a modified example of the subcarrier according to the present invention.

FIG. 6 is a perspective view showing a modified example of the subcarrier according to the present invention.

FIG. 7A is a perspective view illustrating a modification of the subcarrier according to the present invention, and FIG. 7B is a top view illustrating a state where an optical fiber and an optical element are coupled to the subcarrier.

FIG. 8A is a perspective view showing a modification of the subcarrier according to the present invention, and FIG. 8B is a side view illustrating a state where an optical fiber and an optical element are coupled to the subcarrier.

FIG. 9 is a cross-sectional view illustrating a state where an optical fiber and an optical element are coupled to a subcarrier according to the present invention.

FIG. 10 is a cross-sectional view illustrating a state where an optical fiber and an optical element are coupled to a subcarrier according to the present invention.

FIG. 11 is a perspective view illustrating a state in which an optical element is mounted on a subcarrier according to the present invention.

FIG. 12 is a perspective view illustrating an optical element mounting subcarrier according to the present invention.

[Explanation of symbols]

21, 41, 51, 61, 81, 91, 101, 11
2, 121, 131 ... Subcarrier (plate-like body) 22, 42, 62, 84, 94, 122 ... Through hole (light guide path) 27, 47, 88, 98, 108, 118, 128, 1
38: PD chip (optical element) 31: Substrate 33, 89, 99, 109, 119 ... Optical fiber (optical waveguide) M1: Optical module

Claims (5)

[Claims] 1. A plate-like body having light guide paths having ends on both main surfaces is provided on a substrate, and an optical functional surface of an optical element for emitting or receiving light is arranged on one main surface of the plate-like body. An optical element mounting substrate having an optical waveguide that optically couples with an optical functional surface of the optical element on the other main surface side. 2. The optical element mounting board according to claim 1, wherein the light guide path of the plate-like body is formed of a through hole or a transparent body. 3. The optical element mounting substrate according to claim 1, wherein the substrate and the plate-like body are made of the same material. 4. The optical element mounting board according to claim 1, wherein both main surfaces of the plate-shaped body are non-parallel. 5. The optical element mounting board according to claim 1,
An optical module, wherein an optical waveguide body for optically coupling with the optical element is disposed on the other main surface side of the plate-like body.