JP2001083346A - Electric/optic mixed loading wiring board, electricity- light mixed loading module and method for its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To promote the confinement of a light signal in a core layer of an optical waveguide and to suppress light propagation loss. SOLUTION: The electric/optic mixed loading wiring board 10 has a groove 13 with a side wall 13c perpendicular to a light propagation direction in front of an end of the optical waveguide 14, a 1st conductor 13a parallel to the waveguide 14 on the bottom of the groove 13, a solder layer 13b parallel to the conductor 13a on the conductor 13a and columnar conductors 18 which connect the conductor 13a to a substrate 11. High density electric wiring is attained by using the wiring board 10 obtained by laminating and integrating copper-polyimide multiplayer wiring 11a and the polymeric optical waveguide 14. Since it is made unnecessary to reduce the thickness of a lower clad 17 of the optical waveguide by disposing the 1st conductor 13a in the clad 17, the confinement of the light signal in the core 16 of the optical waveguide is promoted and the light propagation loss is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electro-optical hybrid wiring board, an electro-optical hybrid module, and a method of manufacturing the same for use in an optical communication device and the like, and more particularly, to optically coupling an optical waveguide with an end face optical element. The present invention relates to an electro-optical hybrid wiring board, an electro-optical hybrid module, and a method of manufacturing the same.

[0002]

2. Description of the Related Art FIG. 6 is a cross-sectional view of a conventional electro-optical hybrid module for a general light emitting element as an end face type optical element.

In the figure, reference numeral 40 denotes an electric / light mixed wiring board, and this electric / light mixed wiring board 40 is a multilayer ceramic substrate 41.
, Copper-polyimide multilayer wiring 41a, and polymer optical waveguide 4
And 4. Copper polyimide multilayer wiring 41a
Accommodates a via 41b. Further, the polymer optical waveguide 44 includes an upper optical waveguide clad 45, an optical waveguide core 46, and a lower optical waveguide clad 47.

Reference numeral 43 denotes a copper-polyimide multilayer wiring 41a.
The first conductor 4
3a and the solder layer 43b are laminated, and the solder layer 43
The end-face type optical element 42 is mounted on “b” so as to be in contact with the side wall 43 c of the groove 43 and so that the center of the active layer 42 a coincides with the center of the optical waveguide core 46.

When the electro-optical hybrid module of the present embodiment is realized, for example, 4
After forming a lower optical waveguide cladding layer and an optical waveguide core layer (a difference in refractive index between the optical waveguide core and the cladding is, for example, 0.3%) made of fluorinated polyimide by a heat treatment of 00 ° C. or less, the optical waveguide is formed. An etching mask (not shown) for forming an optical waveguide core is formed on the upper surface of the core layer, and reactive ion etching is performed from the upper surface of the optical waveguide core to form an optical waveguide core 46. An upper optical waveguide cladding layer is formed at a temperature of 400 ° C. or less.

Thereafter, an etching mask (not shown) for forming a groove is formed on the upper surface of the upper optical waveguide cladding layer, and reactive ion etching is performed from the upper surface of the upper optical waveguide cladding layer. To form Groove 43
A first conductor 43a (for example, Au / Ni)
/ Cu). Further, after a thin-film solder layer 43b (for example, Au / Sn eutectic solder) is formed on the first conductor 43a, an end surface in a plane parallel to the bottom surface of the groove 43 is formed using a positioning device (not shown). Type optical element 4
2 and the optical axis of the optical waveguide 44, and the bottom surface of the end surface type optical element 42 is brought into contact with the solder layer 43b.
3b is fixed by heating and melting to complete the electro-optical hybrid module. Regarding this point, for example, “H. Takahara et al.,” Optical waveguide interconnec
tions for opto-electronic multichip modules, "SPIE
Optoelectronic Interconnecs, Vol.1849, pp.70-78,199
3 ".

In this method, an optical waveguide is laminated and integrated on a copper-polyimide multilayer wiring, which is a high-density electrical wiring, so that a large number of LSIs and optical elements are electrically or optically connected on an electro-optical hybrid wiring board. There is an advantage that can be.

[0008]

However, in the conventional electro-optical hybrid module as shown in FIG. 6, the center of the active layer 42a of the end face type optical element 42 and the center of the optical axis of the optical waveguide core 46 are aligned. In the case where the upper surface of the copper-polyimide multilayer wiring 41a is used as a reference in the height direction, it is necessary to adjust the thickness of the lower optical waveguide clad 47. In particular, when the optical element is mounted face-down, the lower optical waveguide clad 47 is required. The optical signal cannot be confined in the optical waveguide core 46 because the thickness of the layer is reduced, and the copper polyimide multilayer wiring 41a
There is a problem that the light propagation loss increases due to leakage into the inside.

In the case where the groove 43 is formed by reactive ion etching while controlling the optical waveguide 44 with high precision,
If the optical waveguide 44 is over-etched to a desired depth or more, there is a possibility that electric wiring and conductive pads on the copper polyimide multilayer wiring 41a or the inside of the copper polyimide multilayer wiring 41a is eroded. Further, since the end facet type optical element 42 is mounted on the copper polyimide multilayer wiring 41a having poor thermal conductivity, there is a problem that heat dissipation is poor and optical signal characteristics are deteriorated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to enhance the confinement of an optical signal in an optical waveguide core layer and to suppress the electric propagation loss of an optical signal. An object of the present invention is to provide an embedded wiring board, an electro-optical hybrid module, and a method of manufacturing the same.

[0011]

According to the present invention, in order to achieve the above object, an electro-optical hybrid wiring board according to the present invention has an optical waveguide core sandwiched on an electric wiring layer laminated on a substrate. In an electro-optical hybrid wiring board obtained by laminating an optical waveguide provided with an upper optical waveguide clad and a lower optical waveguide clad having a lower refractive index than the optical waveguide core, in the light propagation direction in front of the end of the optical waveguide. A groove having a side wall perpendicular to the groove,
A first conductor formed on the bottom surface of the groove and parallel to the optical waveguide; a solder layer formed on the first conductor and parallel to the first conductor; And a columnar conductor connecting the conductor and the substrate.

Further, the electro-optical hybrid module according to the present invention comprises:
An electric light formed by laminating an optical waveguide provided with an upper optical waveguide clad and a lower optical waveguide clad having a lower refractive index than the optical waveguide core, with an optical waveguide core interposed therebetween, on an electric wiring layer laminated on the substrate. In the electro-optical hybrid module including the mixed wiring board and an end face optical element optically coupled to the optical waveguide, the electro-optical hybrid wiring board is perpendicular to a light propagation direction in front of an end of the optical waveguide. A groove having a side wall, a first conductor formed on the bottom surface of the groove and parallel to the optical waveguide, and a solder layer formed on the first conductor and parallel to the first conductor Wherein the distance from the surface of the solder layer to the optical axis of the optical waveguide core is the distance from the bottom surface of the edge-type optical element mounted on the solder layer to the center of the active layer of the edge-type optical element. Is set equal to, the end face type optical element, It is characterized in that the optical axis passing through the center of the active layer is fixed to the solder layer on the electro-optical hybrid circuit board in a position which is coincident with the optical axis of the optical waveguide core.

Further, in the electro-optical hybrid module according to the present invention, the first conductor is connected to the substrate by a columnar conductor.

That is, the first conductor is formed in the electric / light mixed wiring layer of the electric / light mixed wiring board in parallel with the optical waveguide surface, and a portion to be the bottom surface of the groove is built in advance. The distance from the surface of the solder layer formed on the conductor to the optical axis of the optical waveguide core is equal to the distance from the end face optical element surface mounted on the solder layer to the center of the active layer of the end face optical element. By setting as above, the end-face type optical element was configured such that the optical axis passing through the center of the active layer in the height direction coincided with the optical axis of the optical waveguide core only by fixing to the solder surface at the bottom of the groove. Things. In addition, the back surface of the first conductor and the multilayer ceramic substrate are connected by a columnar conductor to improve the heat radiation characteristics of the end face optical element mounted on the bottom of the groove.

Further, according to the method of manufacturing an electric / optical hybrid wiring board of the present invention, an upper optical waveguide having a lower refractive index than the optical waveguide core is provided on an electric wiring layer laminated on the substrate with the optical waveguide core interposed therebetween. In a method of manufacturing an electro-optical hybrid wiring board in which an optical waveguide provided with a clad and a lower optical waveguide clad is laminated, a lower optical waveguide clad layer made of a polymer constituting the lower optical waveguide clad is provided on the substrate; Forming an optical waveguide layer by laminating an optical waveguide core layer made of a polymer constituting the above, and an upper optical waveguide cladding layer made of a polymer constituting the upper optical waveguide clad in parallel with the upper surface of the electric wiring layer. Forming a first conductor made of metal in parallel with the optical waveguide layer in an electric / light mixed wiring layer in which the electric wiring layer and the optical waveguide layer are laminated, and further having the same dimension as the first conductor; In parallel, a step of forming a first mask made of a material different from that of the first conductor and having a lower reactive ion etching rate than the material of the optical waveguide layer, and an upper surface of the optical waveguide core layer. Forming a second mask having a reactive ion etching rate smaller than that of the material of the optical waveguide, performing reactive ion etching perpendicular to the upper surface of the optical waveguide core layer, and setting the second mask Removing and forming the optical waveguide core, laminating the upper optical waveguide cladding layer on the optical waveguide core,
Further, a third mask having an inverted pattern of the first mask on the upper surface of the upper optical waveguide cladding layer and having a lower reactive ion etching rate than the material of the optical waveguide is referred to as the first mask. Forming the upper optical waveguide clad layer in parallel with the upper optical waveguide clad layer, and performing the reactive ion etching on the upper optical waveguide clad layer perpendicularly to the upper optical waveguide clad layer, and the optical waveguide for projecting the upper mask. Etching a core and the lower optical waveguide cladding layer to form a groove, removing the third mask, removing the first mask, and removing the first mask from the bottom surface of the groove; Forming the solder layer on the conductor in parallel with the first conductor.

Further, according to the method of manufacturing an electro-optical hybrid module of the present invention, an upper optical waveguide clad having a lower refractive index than the optical waveguide core is provided on an electric wiring layer laminated on a substrate with the optical waveguide core interposed therebetween. And an optical waveguide provided with a lower optical waveguide clad are laminated to form an electro-optical hybrid wiring board, and an electro-optical hybrid mounting the end face type optical element optically coupled to the optical waveguide on the electro-optical hybrid wiring board. In the method for manufacturing a module, a lower optical waveguide clad layer made of a polymer constituting a lower optical waveguide clad, an optical waveguide core layer made of a polymer constituting the optical waveguide core, and the upper optical waveguide clad are formed on the substrate. Forming an optical waveguide layer by laminating an upper optical waveguide cladding layer made of a constituent polymer in parallel with the upper surface of the electric wiring layer, and laminating the electric wiring layer and the optical waveguide layer A first conductor made of metal is formed in the electric / light mixed wiring layer in parallel with the optical waveguide layer, and is made of a material different from the first conductor in a size equal to or more than the same dimension as the first conductor. Forming a first mask having a lower reactive ion etching rate than the material of the optical waveguide layer, and further comprising forming a solder on the optical axis center of the optical waveguide core layer and the first conductor. The optical waveguide layer and the first layer so that a distance between the surface of the layer and the center of the active layer of the end surface type optical element is equal to a distance from a bottom surface of the end surface type optical element mounted on the solder layer. Forming a conductor, and forming a second mask on the upper surface of the optical waveguide core layer, the reactive ion etching rate being smaller than the material of the optical waveguide, and forming the second mask on the upper surface of the optical waveguide core layer. Perpendicular to the reactive ion Forming the optical waveguide core by removing the second mask, laminating the upper optical waveguide clad layer on the optical waveguide core, and further forming the second optical mask on the upper surface of the upper optical waveguide clad layer. Forming a third mask having a reverse pattern of the first mask and having a lower reactive ion etching rate than the material of the optical waveguide in parallel with the first mask; Performing reactive ion etching perpendicular to the layer to etch the upper optical waveguide cladding layer where the third mask is not formed, and the optical waveguide core and the lower optical waveguide cladding layer that project the upper optical waveguide cladding layer. Forming a groove in the groove, removing the third mask, removing the first mask, and flattening the first conductor on the bottom surface of the groove and on the first conductor. Forming a solder layer in a row; and mounting an end face type optical element optically coupled to the optical waveguide.

Further, in the method for manufacturing an electro-optical hybrid module according to the present invention, the side surface on the active layer side of the end surface type optical element is brought into parallel contact with the side wall of the groove on the end side of the optical waveguide. The optical axis of the optical waveguide projected on a plane parallel to the bottom surface of the groove coincides with the optical axis passing through the center of the active layer of the edge type optical element, and the bottom surface of the edge type optical element is parallel to the surface of the solder layer. And heating the solder layer and the end-face type optical element and melting the solder layer to fix the end-face type optical element to the electro-optical hybrid wiring board.

As described above, according to the electro-optical hybrid wiring board, the electro-optical hybrid module and the method of manufacturing the same according to the present invention, it is not necessary to reduce the clad thickness by providing the first conductor in the lower optical waveguide clad. Since the optical signal confinement in the optical waveguide core becomes strong, the light propagation loss can be suppressed. In addition, a first mask serving as an etching stop layer (made of a material having a lower etching rate for reactive ion etching than a polymer optical waveguide material) is provided on a first conductor serving as a bottom surface of a groove for mounting an end face type optical element. In addition to controlling the etching depth of the groove with high accuracy, the problem of over-etching can be solved. Therefore, it is possible to realize an optical coupling structure in which the alignment of the optical axis in the height direction can be easily performed only by bringing the bottom surface of the end face type optical element into contact with the solder layer formed on the bottom surface of the groove. Furthermore, since the back surface of the first conductor formed on the bottom surface of the groove and the multilayer ceramic substrate are connected by the columnar conductor, the thermal resistance of the layer between the bottom surface of the groove and the multilayer ceramic substrate is reduced, and the mounted end surface is reduced. The heat radiation characteristics of the optical device can be improved.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view showing an embodiment of an electro-optical hybrid module according to the present invention. In the drawing, reference numeral 10 denotes an electro-optical hybrid wiring board. , A copper-polyimide multilayer wiring 11 a, and a polymer optical waveguide 14. Vias 11b are housed in the copper-polyimide multilayer wiring 11a. Further, the polymer optical waveguide 14 is formed of the upper optical waveguide clad 1.
5, an optical waveguide core 16 and a lower optical waveguide clad 17.

Reference numeral 13 denotes a copper-polyimide multilayer wiring 11a.
The first conductor 1
3a and the solder layer 13b are laminated, and the solder layer 13
The end-face type optical element 12 is mounted on “b” so as to be in contact with the side wall 13 c of the groove 13 and to make the center of the active layer 12 a coincide with the center of the optical waveguide core 16.

That is, the electro-optical hybrid wiring board 10 is provided on the side wall 13 perpendicular to the light propagation direction in front of the end of the optical waveguide 14.
The first conductor 13a is formed on the bottom surface of the groove 13 in parallel with the optical waveguide 14, and the first conductor 13a is formed on the first conductor 13a.
A solder layer 13b is formed in parallel with the optical waveguide core 1 from the surface of the solder layer 13b as shown in FIG.
6, so that the distance A from the bottom surface of the edge type optical element 12 mounted on the solder layer 13b to the center N of the active layer 12a of the edge type optical element 12 is set to be equal to the distance B to the optical axis M. Have been.

The end facet type optical element 12 includes an active layer 12a.
Are fixed to the solder layer 13b on the electro-optical hybrid wiring board 10 at a position where the optical axis passing through the center of the optical waveguide coincides with the optical axis of the optical waveguide core 16. Further, the first conductor 13a is connected to the substrate 11 by a columnar conductor 18.

The end surface type optical element 12 has, for example, a thickness of 90
5 μm laser array in which the center of the active layer 12a is 5 μm from the surface in μm
μm), and the polymer optical waveguides 14 in which the optical waveguide cores 16 are arranged in an array at the same pitch between channels are a polymer having a high affinity for the copper-polyimide multilayer wiring 11a and a high light transmittance (for example, fluorinated polyimide). The optical waveguide core 16 has a thickness and a width of 8 μm, for example. The upper and lower optical waveguide clads 15 and 17 have a thickness of 2 μm, for example.
0 μm. The first conductor 13a (for example, Au / Ni
/ Cu), the upper surface of a solder layer 13b (for example, Au / Sn eutectic solder) having a thickness of 5 μm, for example,
It is set parallel to the surface of the optical waveguide 14 at a position of 19 μm from the upper surface of the copper polyimide multilayer wiring 11a.

The ends of the optical waveguide cores 16 arranged in an array on the groove 13 side are connected to the copper-polyimide multilayer wiring 11a.
Is parallel to the side wall 13c of the groove 13, and the side wall 13c of the groove 13 is perpendicular to the upper surface of the solder layer 13b.

Here, the active layer 12a of the edge type optical element 12
The side surface is parallel to the side wall 13c of the groove 13, and the back surface of the first conductor 13a is connected to the multilayer ceramic substrate 11 by, for example, a columnar conductor 18 made of copper and having a diameter of 100 μm. . The line connecting the end between the optical waveguide cores 16 arranged in an array in parallel with the upper surface of the copper-polyimide multilayer wiring 11a does not necessarily have to be on the same plane as the side wall 13c of the groove 13.

The optical waveguide cores 1 arranged in an array
6 may not be parallel to the side wall 13c of the groove 13, and in particular, the optical waveguide cores 1 may be arranged in an array.
In order not to cause resonance between the end of the optical waveguide core 6 and the side surface on the active layer 12a side of the end surface type optical element 12, the surface connecting the ends between the optical waveguide cores 16 arranged in an array is formed by the side wall of the groove. 13
It is good to be slightly inclined (for example, 8 ° to 9 °) with respect to c.

Since the distance (= 5 μm) between the bottom surface of the edge-type optical element 12 and the center of the active layer 12a is equal to the distance between the upper surface of the solder layer 13b and the center of the polymer optical waveguide core 16, the edge-type light source is used. By simply bringing the bottom surface of the element 12 into contact with the upper surface of the solder layer 13b, the polymer optical waveguide 14
And the optical axis of the end surface type optical element 12 can be matched.

Further, by connecting the first conductor 13a formed on the bottom surface of the groove 13 and the multilayer ceramic substrate 11 by the columnar conductor 18, the thermal resistance of the layer between the bottom surface of the groove 13 and the multilayer ceramic substrate 11 is increased. Can be reduced to 2/3 or less, so that the heat radiation characteristics of the end surface type optical element 12 fixed to the solder layer 13b can be improved.

In this embodiment, the light emitting element mounted face-down as the facet type optical element 12 has been described.
In addition to light emitting elements, light I such as waveguide type light receiving elements and optical switches
C is fine. Also, as a substrate for laminating the optical waveguide layer,
Although an example of a copper-polyimide multilayer wiring board has been described, a multilayer or single-layer ceramic wiring board, a Si substrate, or a printed board having solder heat resistance may be used. The optical waveguide material may be an epoxy resin or a silicone resin in addition to the fluorinated polyimide. The solder material is not limited to Au / Sn, but may be Sn / Pb, a conductive adhesive, or the like.

FIGS. 3A to 3D and 4E to 4E.
(G) is a process drawing showing an example of a method for manufacturing an electro-optical hybrid module according to the present invention. In the figure, reference numeral 20 denotes an electro-optical hybrid wiring board of the present invention, 21 denotes a multilayer ceramic substrate,
1a is a copper-polyimide multilayer wiring, 21b is a via, 23 is a groove, 23a and 23b are first conductors and solder layers formed on the bottom surface of the groove 23, 23c is a side wall of the groove 23, 24
Is a polymer optical waveguide, 25a is an upper optical waveguide cladding layer,
26 is an optical waveguide core, 26a is an optical waveguide core layer, 27a
Is a first lower optical waveguide cladding layer, 27b is a second lower optical waveguide cladding layer, 28 is a columnar conductor, 29 is a first mask, 29a is a second mask, and 29b is a third mask.

First, a photosensitive polyimide layer is formed by spin coating and curing on a multilayer ceramic substrate 21 made of, for example, alumina, and copper wiring is formed thereon by electrolytic and electroless plating. The multilayer wiring 21a is formed. The copper wiring between the layers
They are connected by vias 21b made of copper formed by electrolytic and electroless plating.

Next, a 14 μm-thick first lower optical waveguide clad layer 27a made of fluorinated polyimide is formed on the surface of the copper-polyimide multilayer wiring 21a by spin coating and curing (for example, 400 ° C. or lower). The first conductor 23a made of, for example, Au / Ni / Cu on the upper surface and patterned into a desired pattern is further provided with a first conductor 2a.
A first mask 29 made of, for example, Ti is formed on 3a.
Is formed by, for example, electrolytic and electroless plating or vapor deposition at about 4000 A. Also, the first conductor 2
A columnar conductor 28 made of copper is formed between the back surface of 3a and the multilayer ceramic substrate 21 by electrolytic and electroless plating (FIG. 3A).

Further, a second lower optical waveguide cladding layer 27b made of the same material as described above is spin-coated by 6 μm.
It is formed by curing (FIG. 3B).

Next, a polymer optical waveguide core layer 26a having a thickness of 8 μm (the relative refractive index between the optical waveguide core and the clad is, for example, 0.3%) is applied by spin coating and curing (for example, 400 ° C. or lower). Then, a second mask 29b made of, for example, Ti is formed at a position where the polymer optical waveguide 24 is to be formed.
Is formed by vapor deposition, for example, at about 4000 A (FIG. 3C).

Next, reactive ion etching is performed from the surface of the upper optical waveguide core layer 26a to form the optical waveguide core 26, and then the second mask 29b is removed with hydrofluoric acid (FIG. 3D).

Thereafter, the lower optical waveguide clad 27a,
The upper optical waveguide cladding layer 25a having the same composition as
After being formed by spin coating and curing (for example, 400 ° C. or lower), the upper optical waveguide cladding layer 25a is formed.
On the front surface, a third mask 29c whose projection surface is the inverse of the first mask 29 is formed by vapor deposition, for example, at about 4000A (FIG. 4E).

Thereafter, the upper optical waveguide clad layer 25a, the optical waveguide core 26, and the second lower optical waveguide clad layer 27b in the openings of the third mask 29c are subjected to reactive ion etching until the first mask 23a appears. Then, the first mask 29 is removed with hydrofluoric acid or the like to form a groove (FIG. 4).
(F)).

Further, on the first conductor 23a, for example,
The thin film solder layer 23b made of Au / Sn eutectic solder is
By forming, for example, 5 μm by vapor deposition, the electro-optical hybrid wiring board of the present invention is completed (FIG. 4G).

The optical waveguide cores 2 arranged in an array
The line connecting the end of the groove 6 in parallel with the upper surface of the copper-polyimide multilayer wiring 21a may not be in the same plane as the side wall 23c of the groove 23. The surface connecting the ends of the optical waveguide cores 26 arranged in an array may not necessarily be parallel to the side wall 23c of the groove 23. In particular, the end of the polymer optical waveguide 24 and the active layer of the end surface type optical element may be used. In order not to cause resonance with the side surface, the surface connecting the ends of the optical waveguide cores 26 arranged in an array is slightly (for example, 8 ° to 9 °) with respect to the side wall 23c of the groove 23. It may be inclined. Also, the first, second,
As the third mask 29, 29a, 29b, a metal (such as Al) other than Ti, an SPP resist, or the like may be used.

As a substrate for laminating the optical waveguide layer,
Although an example of a copper-polyimide multilayer wiring board has been described, a multilayer or single-layer ceramic wiring board, a Si substrate, or a printed board having solder heat resistance may be used. The optical waveguide material may be an epoxy resin or a silicone resin in addition to the fluorinated polyimide. The solder material is not limited to Au / Sn, but may be Sn / Pb, a conductive adhesive, or the like.

FIGS. 5A to 5C are views showing an example of a method of mounting an end face type optical element in the electro-optical hybrid module according to the present invention. In the figure, reference numeral 30 denotes an electro-optical mixed wiring board,
31 is a multilayer ceramic substrate, 31a is a copper-polyimide multilayer wiring, 31b is a via, 32 is an end-face optical element, 32a is the center of the active layer of the end-face optical element 32, and 32b is the active layer 32a side of the end-face optical element 32. Side surface, 33 is a groove, 33a is a first conductor, 33b is a solder layer, 33c is a side wall of the groove 33,
34 is a polymer optical waveguide, 35 is an upper optical waveguide clad,
36 is an optical waveguide core, 37 is a lower optical waveguide clad, 3
Reference numeral 8 denotes a columnar conductor.

As described with reference to FIG.
Is equal to the distance between the upper surface of the solder layer 33b and the optical axis of the polymer optical waveguide 34. Further, a line connecting the end of the optical waveguide core 36 arranged in an array on the groove 33 side in parallel with the upper surface of the copper-polyimide multilayer wiring 31a is parallel to the side wall 33c of the groove 33,
The side wall 33c of the groove 33 is perpendicular to the upper surface of the solder layer 33b.

The optical waveguide cores 3 arranged in an array
The line connecting the end of the groove 6 in parallel with the upper surface of the copper-polyimide multilayer wiring 31 a may not be in the same plane as the side wall 33 c of the groove 33. The surface connecting the ends of the optical waveguide cores 36 arranged in an array need not be parallel to the side wall 33c of the groove 33. In particular, the end of the polymer optical waveguide 34 and the end surface type optical element 32
In order not to generate resonance with the side surface 32b on the active layer 32a side, the surface connecting the ends of the optical waveguide cores 36 arranged in an array is slightly (for example, 8 °) with respect to the side wall 33c of the groove. ９9 °) may be inclined.

First, while adjusting the longitudinal direction of the center of the active layer 32a of the end surface type optical element 32 so as to coincide with the center of the width of the polymer optical waveguide 34, for example, by using a positioning device (not shown). The side surface on the side of the active layer 32a is
(FIG. 5A). Next, the bottom surface of the end surface type optical element 32 is pressed against the upper surface of the solder layer 33b (FIG. 5B). Finally, the solder layer 33b is melted by heating to fix the end face optical element 32, thereby mounting the end face optical element (FIG. 5).
(C)).

In this embodiment, the case where a face-down mounted light emitting element is used as the end face type optical element 32 has been described. However, not only the face-up mounting but also a waveguide type light receiving element or an optical element may be used. Light I for switches, etc.
C is fine.

[0047]

As described above, according to the present invention, the electric-optical hybrid wiring board has a groove having a side wall perpendicular to the light propagation direction in front of the end of the optical waveguide, a bottom surface of the groove, and A first conductor formed parallel to the optical waveguide, a solder layer formed on the first conductor and parallel to the first conductor, and a columnar conductor connecting the first conductor to the substrate. The high-density electrical wiring is realized by using an electro-optical hybrid wiring board in which a polymer optical waveguide is laminated and integrated on a copper-polyimide multilayer wiring, and the first conductor is provided in the lower optical waveguide cladding. It is not necessary to reduce the thickness, and the optical signal confinement in the optical waveguide core becomes stronger.
Light propagation loss can be suppressed.

The distance from the surface of the solder layer to the optical axis of the optical waveguide core is set to be equal to the distance from the bottom surface of the edge type optical element mounted on the solder layer to the center of the active layer of the edge type optical element. In addition, the end-face type optical element is fixed to the solder layer on the electro-optical hybrid wiring board at a position where the optical axis passing through the center of the active layer coincides with the optical axis of the optical waveguide core. Since the first mask (which is made of a material having a lower etching rate for reactive ion etching than the polymer optical waveguide material) is formed as an etching stop layer on the first conductor which is the bottom surface of the groove for mounting the optical element. In addition to being able to control the etching depth of the groove with high accuracy, the problem of over-etching can be solved. Therefore, it is possible to realize an optical coupling structure in which the alignment of the optical axis in the height direction can be easily performed only by bringing the bottom surface of the end face type optical element into contact with the solder layer formed on the bottom surface of the groove.

Furthermore, since the back surface of the first conductor formed on the bottom surface of the groove and the multilayer ceramic substrate are connected by the columnar conductor, the thermal resistance of the layer between the bottom surface of the groove and the multilayer ceramic substrate is reduced. The heat radiation characteristics of the mounted end face type optical element can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of an electro-optical hybrid module according to the present invention.

FIG. 2 is a partially enlarged view of FIG.

FIGS. 3A to 3D are diagrams (part 1) illustrating an example of a method for manufacturing an electro-optical hybrid module according to the present invention.

4 (e) to 4 (g) are views (part 2) illustrating an example of a method for manufacturing an electro-optical hybrid module according to the present invention.

FIG. 5 is a diagram showing an example of a method of optically coupling an end face type optical element and an optical waveguide in the hybrid electro-optical module of the present invention.

FIG. 6 is a view showing a conventional electro-optical hybrid module.

[Explanation of symbols]

 10, 20, 30 Electric / optical hybrid wiring board 11, 21, 31, Multilayer ceramic substrate 11a, 21a, 31a Copper / polyimide multilayer wiring 11b, 21b, 31b Via 12, 32 Edge type optical element 12a, 32a Active layer 32b Edge type light Side surface on active layer side of device 13, 23, 33 Groove 13a, 23a, 33a First conductor 13b, 23b, 33b Solder layer 13c, 23c, 33c Side wall of groove 14, 24, 34 Polymer optical waveguide 15, 25, 35 Polymer upper optical waveguide clad 25a Upper optical waveguide clad layer 16, 26, 36 Optical waveguide core 26a Optical waveguide core layer 17, 27, 37 Lower optical waveguide clad 27a First lower optical waveguide clad layer 27b Second lower optical waveguide clad Layers 18, 28, 38 Columnar conductors 29, 29a, 29b First, second, third mats School

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hideki Tsuneji 2-3-1 Otemachi, Chiyoda-ku, Tokyo F-term (reference) 2H047 KA04 MA07 PA21 PA24 PA28 QA05 TA36

Claims (6)

[Claims] An optical waveguide having an upper optical waveguide clad and a lower optical waveguide clad having a lower refractive index than an optical waveguide core is laminated on an electric wiring layer laminated on a substrate with the optical waveguide core interposed therebetween. A groove having a side wall perpendicular to a light propagation direction in front of an end of the optical waveguide; and a first groove formed at a bottom surface of the groove and parallel to the optical waveguide. And a solder layer formed on and parallel to the first conductor, and a columnar conductor connecting the first conductor and the substrate. Mixed light and light wiring board. 2. An optical waveguide having an upper optical waveguide clad and a lower optical waveguide clad having a lower refractive index than the optical waveguide core, with the optical waveguide core interposed therebetween, on an electric wiring layer laminated on the substrate. An electro-optical hybrid module comprising: an electro-optical hybrid wiring board formed as described above; and an end face type optical element optically coupled to the optical waveguide, wherein the electro-optical hybrid wiring board has a light propagation direction in front of an end of the optical waveguide. A groove having a side wall perpendicular to the first conductor, a first conductor formed at the bottom of the groove and parallel to the optical waveguide, and on the first conductor and parallel to the first conductor. And a distance from a surface of the solder layer to an optical axis of the optical waveguide core is determined from a bottom surface of the end face type optical element mounted on the solder layer to an active layer of the end face type optical element. Is set equal to the distance to the center of the The end face type optical element is fixed to the solder layer on the electro-optical hybrid wiring board at a position where an optical axis passing through the center of the active layer coincides with an optical axis of the optical waveguide core. Optical mixed module. 3. The electro-optical hybrid module according to claim 2, wherein the first conductor is connected to the substrate by a columnar conductor. 4. An optical waveguide having an upper optical waveguide clad and a lower optical waveguide clad having a lower refractive index than the optical waveguide core, with the optical waveguide core interposed therebetween, on an electric wiring layer laminated on the substrate. In the method for manufacturing an electro-optical hybrid wiring board, a lower optical waveguide clad layer made of a polymer constituting a lower optical waveguide clad, an optical waveguide core layer made of a polymer constituting the optical waveguide core, on the substrate, Forming an optical waveguide layer by laminating an upper optical waveguide cladding layer made of a polymer constituting the upper optical waveguide cladding in parallel with the upper surface of the electric wiring layer; and laminating the electric wiring layer and the optical waveguide layer. A first conductor made of a metal is formed in the electro-optical hybrid wiring layer in parallel with the optical waveguide layer, and is made of a material different from the first conductor in a size equal to or more than the same dimension as the first conductor. One the optical waveguide material reactive than a of the layer ion etching rate smaller first
Forming a mask, and forming a second mask on the upper surface of the optical waveguide core layer, the reactive ion etching rate being smaller than the material of the optical waveguide, and forming the second mask on the upper surface of the optical waveguide core layer. Vertical reactive ion etching to remove the second mask to form the optical waveguide core; laminating the upper optical waveguide clad layer on the optical waveguide core; On the upper surface of the cladding layer, the first
Forming a third mask in parallel with the first mask, the third mask having a reverse pattern of the mask and having a lower reactive ion etching rate than the material of the optical waveguide; By performing reactive ion etching perpendicular to the upper optical waveguide clad layer where the third mask is not formed, and etching the optical waveguide core and the lower optical waveguide clad layer that project the upper optical waveguide clad layer. Forming a groove and removing the third mask; removing the first mask; and forming a groove on the bottom surface of the groove and on the first conductor in parallel with the first conductor. A method for manufacturing an electro-optical hybrid wiring board, comprising: a step of forming a solder layer. 5. An optical waveguide having an upper optical waveguide clad and a lower optical waveguide clad having a lower refractive index than the optical waveguide core, with the optical waveguide core interposed therebetween, on an electric wiring layer laminated on the substrate. Forming an electro-optical hybrid wiring board, and mounting the end face type optical element that optically couples with the optical waveguide on the electro-optical hybrid wiring board. A lower optical waveguide clad layer made of a polymer constituting the optical waveguide clad, an optical waveguide core layer made of a polymer constituting the optical waveguide core, and an upper optical waveguide clad layer made of a polymer constituting the upper optical waveguide clad. Forming an optical waveguide layer by laminating in parallel with the upper surface of the electric wiring layer; and forming a first conductive layer made of metal in an electric / optical hybrid wiring layer in which the electric wiring layer and the optical waveguide layer are laminated. Is formed in parallel with the optical waveguide layer, and is made of a material different from that of the first conductor and in parallel with the first conductor at a dimension equal to or larger than that of the first conductor, and has a reactive ion etching rate lower than that of the material of the optical waveguide layer. Small first
Forming a mask, wherein the distance between the center of the optical axis of the optical waveguide core layer and the surface of the solder layer formed on the first conductor is the same as that of the end face mold mounted on the solder layer. Forming the optical waveguide layer and the first conductor so as to be equal to the distance from the bottom surface of the optical element to the center of the active layer of the end surface type optical element; and Forming a second mask having a smaller reactive ion etching rate than the material of the optical waveguide, performing reactive ion etching perpendicular to the upper surface of the optical waveguide core layer, and removing the second mask; Forming the optical waveguide core by performing the above steps; laminating the upper optical waveguide cladding layer on the optical waveguide core; and forming the first optical waveguide cladding layer on the upper surface of the upper optical waveguide cladding layer.
Forming a third mask in parallel with the first mask, the third mask having a reverse pattern of the mask and having a lower reactive ion etching rate than the material of the optical waveguide; By performing reactive ion etching perpendicular to the upper optical waveguide clad layer where the third mask is not formed, and etching the optical waveguide core and the lower optical waveguide clad layer that project the upper optical waveguide clad layer. Forming a groove and removing the third mask; removing the first mask; and forming a groove on the bottom surface of the groove and on the first conductor in parallel with the first conductor. A method for manufacturing an electro-optical hybrid module, comprising: a step of forming a solder layer; and a step of mounting an end face type optical element that optically couples with the optical waveguide. 6. The light guide projected on a plane parallel to a bottom surface of the groove, wherein a side surface on the active layer side of the end surface type optical element is brought into parallel contact with a side wall of the groove on the end side of the optical waveguide. The optical axis of the wave path is aligned with the optical axis passing through the center of the active layer of the end face type optical element, and the bottom surface of the end face type optical element is brought into parallel contact with the surface of the solder layer, so that the solder layer and the end face type light The method for manufacturing an electro-optical hybrid module according to claim 5, wherein the end face type optical element is fixed to the electro-optical hybrid wiring board by heating the element and melting the solder layer.