Composite substrate

Abstract

This invention provides a technology that facilitates optical coupling and electrical connection in the mounting of functional devices onto a composite substrate including a conductor pattern and an optical waveguide. [Solution] The composite substrate 10A includes a wiring substrate 11A and a substrate with optical waveguides 12A. The wiring substrate 11A includes an insulating layer and a conductor pattern. The substrate with optical waveguides 12A includes a substrate 121 and an optical waveguide layer 122, the optical waveguide layer 122 includes a first cladding layer 122A, a second cladding layer 122C, and a core 122B provided between them. The upper surface of the optical waveguide layer 122 of the substrate with optical waveguides 12A includes a third region R3 where the second cladding layer 122C is provided and a fourth region R4 where the second cladding layer 122C is not provided, the fourth region R4 has a groove GR extending along the boundary between the third region R3 and the fourth region R4, and the core 122B has an end face adjacent to the upper space of the groove GR.

Claims

1. A wiring board comprising one or more insulating layers and one or more first conductor patterns, having a first surface and a second surface which is its back surface, wherein the first surface comprises one or more first regions and one or more second regions which are recessed relative to the one or more first regions, one of the one or more first conductor patterns is located in the one or more first regions, and the height of the one or more second regions is lower than the lower surface of one of the one or more first conductor patterns located in the one or more first regions, A substrate comprising a substrate and an optical waveguide layer provided thereon, wherein each optical waveguide layer comprises a first cladding layer provided on the substrate, a second cladding layer provided on the first cladding layer, and one or more cores provided between the first cladding layer and the second cladding layer, wherein the optical waveguide layers are each placed on the one or more second regions such that they are located above the substrate, and the height of the lower surface of the one or more cores is higher than that of the one or more first regions, and Equipped with, At least one of the one or more optical waveguide substrates is a composite substrate in which the surface on which the optical waveguide layer is provided includes a third region on which the second cladding layer is provided and a fourth region on which the second cladding layer is not provided, the fourth region has a groove extending along the boundary between the third region and the fourth region, and the one or more cores have end faces adjacent to the space above the groove.

2. The composite substrate according to claim 1, wherein the depth of the groove is in the range of 20 μm or more and 50 μm or less.

3. The composite substrate according to claim 1, wherein the width of the groove is within the range of 20 μm or more and 200 μm or less.

4. The composite substrate according to claim 1, wherein the upper surface of the substrate is recessed at the position of the groove, corresponding to the groove.

5. The composite substrate according to claim 1, wherein in at least one of the one or more substrates with optical waveguides, the first cladding layer includes a first portion provided at the location of the third region and a second portion provided at the location of the fourth region.

6. The composite substrate according to claim 5, wherein the bottom surface of the groove is part of the upper surface of the second portion.

7. The composite substrate according to claim 5, wherein the bottom surface of the groove is part of the upper surface of the substrate.

8. The composite substrate according to claim 1, wherein the height of the upper surface of the substrate is lower than the height of the one or more first regions.

9. The composite substrate according to claim 1, wherein the lower surface of the one or more cores has a height of 100 μm or less with respect to the one or more first regions.

10. The composite substrate according to claim 1, further comprising one or more stress relaxation layers interposed between the one or more optical waveguide substrates and the one or more second regions.

11. The composite substrate according to claim 10, wherein each of the one or more stress relaxation layers has an elastic modulus in the range of 0.1 MPa to 3 GPa.

12. The composite substrate according to claim 10, wherein each of the one or more stress relaxation layers has a thickness within the range of 5 μm to 50 μm.

13. At least one of the one or more optical waveguide substrates further includes a second conductor pattern provided between the substrate and the optical waveguide layer, The composite substrate according to claim 1, wherein in each of the at least one optical waveguide substrate further including the second conductor pattern, the second cladding layer is provided such that a portion of the upper surface of the first cladding layer is exposed, and the exposed portion is provided with a plurality of through holes, each extending to the second conductor pattern.

14. The composite substrate according to claim 1, wherein the one or more insulating layers include an insulating resin layer, and the substrate includes a glass substrate.

15. The composite substrate according to claim 1, which is an interposer.

16. A composite substrate according to any one of claims 1 to 15, A first functional device mounted on the composite substrate and optically coupled to at least one of the one or more optical waveguide substrates by butt coupling, A second functional device mounted on the composite substrate and electrically connected to the first functional device, A photoelectric fusion device equipped with [a specific feature].

17. The photoelectric fusion apparatus according to claim 16, further comprising a refractive index adjusting agent layer having a portion interposed between the first functional device and at least one of the one or more optical waveguide substrates.

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