JP2015075588A - Planar optical waveguide substrate and optical module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a planar optical waveguide substrate (PLC) capable of preventing conduction failure due to positional displacement and surface damages when connected, and to provide an optical module having the same.SOLUTION: A PLC 150 according to an embodiment of the present invention includes a base substrate 157 and an insulating film 158 that covers the base substrate and electrical wiring 155, the electrical wiring being embedded in the PLC 150. An upper surface of the PLC has recessed sections that form openings 160 where electrodes 156 electrically connected to the electrical wiring are placed. The upper surface of the PLC is recessed relative to upper surfaces of the electrodes in areas of the openings not occupied by the electrodes. In other words, height d (positive upward) of the upper surface of the PLC with respect to the upper surfaces of the electrodes satisfies d<0.

Description

  The present invention relates to a substrate including a planar optical waveguide and an optical module including the substrate.

  In recent years, ROADM (Reconfigurable Optical Add / Drop Multiplexer) technology has been devised to increase the speed and capacity of optical communications. In an optical network based on ROADM, a wavelength division multiplexing transmission system is used, and an optical signal having an arbitrary wavelength can be branched and inserted without being converted into an electric signal. In addition, in an optical network based on ROADM, when a route through which an optical signal of each wavelength passes is changed (or newly established or abolished), the route is changed without performing work such as connection work, that is, reconfiguration is performed. It is possible (Reconfigurable).

  In order to realize ROADM, a switch device (also referred to as a multicast switch) that is provided between the ROADM network and the client device and that can input and output a plurality of wavelengths and that can change the path is required. That is, a switch device used in ROADM has a function of receiving an optical signal input from a client device and inserting it into a ROADM network path (also referred to as an Add function), and an optical signal branched from the ROADM network path as a client. It has a function of outputting to a device (also referred to as a Drop function), and the path through which the optical signal passes can be changed dynamically. In this specification, the number that can be connected to the route of the ROADM network in the switch device is called the number of routes, and the number that can be connected to the client device is called the number of wavelengths.

  A switch device used in ROADM is generally manufactured using a planar optical waveguide substrate (PLC), and includes a number of optical waveguides in a chip (substrate). The number of paths and wavelengths that can be processed by the switch device. As the number increases, the number of optical waveguides in the chip increases. For example, a switch device having 8 routes and 16 wavelengths is composed of 8 arrays of 1 × 16 optical splitters provided on one chip and 4 arrays of 8 × 1 provided on four chips, respectively. The optical splitter (total 16 arrays) is provided, and the optical splitter and the optical switch are respectively formed in the PLC. In particular, in a PLC having an optical switch, as many as 32 optical waveguides are arranged close to each other on the side connected to the optical splitter, and a heater for selecting an optical signal path is provided in the vicinity of the optical waveguide. . Further, each heater is connected to the outside through electrical wiring provided in the PLC having the optical switch. In recent years, switching devices used in ROADMs have been required to support a larger number of paths and wavelengths and to be reduced in size, and in order to realize this, an optical waveguide included in a PLC having an optical switch. It is necessary to reduce the pitch between the optical waveguides and between the electrical wirings at the same time as increasing the number of electrical wirings and the number of electrical wirings.

  Conventionally, a PLC having an optical switch and a wiring board for connecting electrical wiring in the PLC to the outside are connected by a conductive wire (also referred to as wire bonding), and the control unit is connected via the wiring board. Etc. were connected. However, particularly when the number of optical waveguides is large, connection work is complicated in wire bonding, which may cause a problem of peeling of the conductive wires. Further, it is necessary to secure a space for arranging the conductive wires and the wiring board, which hinders a reduction in the size of the PLC.

  Instead of wire bonding, a method of directly connecting a flexible printed wiring board (FPC) having electrical wiring to the PLC (also referred to as direct bonding) can be used. Patent Document 1 discloses a technique for connecting an electrode on a PLC and an electrode on an FPC using an ACF. In this case, the FPC and the PLC are connected by sandwiching and pressing an anisotropic conductive film (ACF) having both a conductive function and an adhesive function between the FPC and the PLC.

JP 2008-233471 A

  FIG. 9A is a cross-sectional view illustrating a connection configuration of the PLC 10, the FPC 20, and the ACF 30 described in Patent Document 1. The PLC 10 includes a substrate 12 and an insulating film 13 that covers the substrate 12, and an electrode 11 is provided in an opening provided in the insulating film 13. The FPC 20 includes a substrate 21 and an electrode 22 provided on the surface of the substrate 21. The ACF 30 includes a film-like adhesive 31 and conductive particles 32 mixed in the adhesive 31. By aligning the positions of the electrode 11 of the PLC 10 and the electrode 22 of the FPC 20, sandwiching the ACF 30 between the PLC 10 and the FPC 20, and applying pressure in a direction in which the PLC 10 and the FPC 20 are brought close together, the PLC 10 and the FPC 20 are bonded and made conductive. .

  In Patent Document 1, the width W of the electrode 11 of the PLC 10 is made larger than the width L of the electrode 22 of the FPC 20, and the height d of the upper surface of the insulating film 13 relative to the surface including the upper surface of the electrode 11 in the PLC 10 is positive. ) For d ≧ 0. With such a configuration, even when the PLC 10 and the FPC 20 are slightly shifted from each other, it is possible to prevent the insulating film 13 from interfering with the electrode 22 to cause poor conduction between the electrode 22 and the electrode 11.

  However, in the technique described in Patent Document 1, when the PLC 10 and the FPC 20 are greatly displaced (for example, when the displacement is larger than the difference obtained by subtracting the width L from the width W), problems such as conduction failure occur. . FIG. 9B is a cross-sectional view of the connection portion when d is greater than zero. In such a configuration, when the PLC 10 and the FPC 20 are positioned greatly deviated from each other, the electrode 11 and the electrode 22 are not in contact with each other, and the electrode 11 and the electrode 22 are in contact with each other obliquely, resulting in poor conduction over time. In addition, there is a possibility that problems such as destruction of the insulating film 13 by applying pressure from the electrode 22 may occur. In order to prevent this problem, it is conceivable to increase the difference obtained by subtracting the width L from the width W. However, since it is required to reduce the size of the PLC 10 as described above, the width W of the electrode 11 is increased. Is not desirable. Further, there is a manufacturing limit in reducing the width L of the electrode 22 of the FPC 20.

  FIG. 9C is a cross-sectional view of the connection portion when d is equal to 0. In such a configuration, when the PLC 10 and the FPC 20 are positioned greatly deviated from each other, the electrode 11 and the electrode 22 are likely to conduct, but the pressure from the electrode 22 to the electrode 11 and the insulating film 13 via the conductive particles 32 is increased. Is given. As a result, the electrode 11 formed of metal or the like is hard and is not easily damaged, but the insulating film 13 formed of glass or the like may be damaged by pressure.

  The present invention has been made in view of the above-described problems, and can suppress a conduction failure caused by misalignment at the time of connection and a planar optical waveguide substrate (which can suppress surface damage). PLC) and an optical module including the PLC.

  One aspect of the present invention is an optical module including a wiring board and a planar optical waveguide substrate connected to the wiring board, wherein the wiring board is provided on the first substrate and the first substrate. The planar optical waveguide substrate comprising: a first electrical wiring that is provided; and a first electrode that is provided on the first substrate and is electrically connected to the first electrical wiring. Is a second substrate, an optical waveguide provided inside the second substrate, a second electrical wiring provided inside the second substrate, and a surface of the second substrate An opening formed by recessing a part of the second electrode, and a second electrode provided on the second substrate in the opening and electrically connected to the electrical wiring, And the second electrode is disposed in the opening with respect to the surface of the second electrode. The said surface of said second substrate other than the region is recessed in said opening, the first electrode and the second electrode is characterized in that it is electrically connected.

  Another aspect of the present invention is a planar optical waveguide substrate, a substrate, an optical waveguide provided inside the substrate, electrical wiring provided inside the substrate, and a surface of the substrate. An opening formed by a part of the recess, and an electrode provided on the substrate in the opening and electrically connected to the electrical wiring, and on the surface of the electrode On the other hand, the surface of the substrate other than the region where the electrode is disposed in the opening is concave.

  According to the planar optical waveguide substrate and the optical module including the same according to the present invention, an opening is provided on the surface of the substrate, an electrode is disposed in the opening, and the electrode is disposed in the opening with respect to the surface of the electrode. Since the surface of the substrate other than the region where the substrate is disposed is depressed, it is possible to suppress the electrode conduction failure even if the position shift occurs, and to suppress the damage of the substrate surface around the electrode.

It is a top view of a switch device concerning one embodiment of the present invention. It is a schematic diagram of the splitter part and switch part which concern on one Embodiment of this invention. It is a top view of the switch part concerning one embodiment of the present invention. It is the upper side figure and sectional drawing of PLC which concern on one Embodiment of this invention. It is the upper side figure and sectional drawing of FPC which concern on one Embodiment of this invention. It is sectional drawing of the connection part of PLC and FPC which concerns on one Embodiment of this invention. It is sectional drawing of the connection part of PLC and FPC which concerns on one Embodiment of this invention. It is a top view of PLC which concerns on one Embodiment of this invention. It is sectional drawing of the connection part of conventional PLC and FPC.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the embodiments. In the drawings described below, components having the same function are denoted by the same reference numerals, and repeated description thereof may be omitted.

(First embodiment)
FIG. 1 is a top view of the switch device 100 according to the present embodiment. The switch device 100 can be connected between a ROADM network having a plurality of routes and a plurality of client devices. The switch device 100 can branch an optical signal from a route of the ROADM network to a desired client device as a Drop function, and can insert a signal from the client device to a desired route of the ROADM network as an Add function. The switch device 100 has a dual configuration (that is, a configuration having a Drop function and an Add function) having two sets of eight routes and sixteen wavelengths.

  The switch device 100 includes two sets of a housing 110 including one splitter unit 120 and four switch units 130 connected to each splitter unit 120. Each splitter unit 120 is connected to the path-side optical fiber 101, and each switch unit 130 is connected to the client-side optical fiber 102. The splitter unit 120 and the switch unit 130 are connected by a shuffle fiber array 140 having a plurality of optical fibers that are three-dimensionally rearranged.

  FIG. 2 is a schematic diagram of the splitter unit 120 and the switch unit 130. The splitter unit 120 includes eight optical splitters 121 on one chip (substrate). The optical splitter 121 is a 1 × 16 optical splitter, and has one common port 122 at one end and 16 branch ports 123 at the other end. The optical signal input from the common port 122 is divided and output to each branch port 123. Alternatively, the optical signals input from the branch ports 123 are joined to the common port 122 and output. The splitter unit 120 is manufactured in a PLC formed using, for example, quartz.

  The switch unit 130 includes four optical switches 131 on one chip (substrate). The optical switch 131 is a 1 × 8 optical switch that can select a path of an optical signal by being controlled by a control unit (not shown), and includes one common port 132 at one end and eight branch ports 133 at the other end. Have The optical signal input from the common port 132 is output to one of the branch ports 133 according to control. Alternatively, the optical signal input from each branch port 133 is output to the common port 132 or discarded without being output depending on the control. As an exemplary configuration, the optical switch 131 includes a plurality of MZIs connected in multiple stages, and the control unit drives the heater provided in each MZI to change the branching ratio of each MZI, thereby changing the optical switch 131. The path of the optical signal through can be selected. The switch unit 130 is manufactured in a PLC formed using, for example, silicon.

  The splitter unit 120 and the switch unit 130 are connected by a shuffle fiber array 140. The shuffle fiber array 140 has a plurality (128 in the present embodiment) of optical fibers provided in a three-dimensionally rearranged manner between the splitter unit 120 and the switch unit 130. The 128 optical fibers of the shuffle fiber array 140 are respectively divided into eight branch ports 123 (total 128) of the eight optical splitters 121 included in one splitter unit 120 and four included in the four switch units 130. Are connected to branch ports 133 (128 in total). The 16 branch ports 123 included in each optical splitter 121 are connected to branch ports 133 of different optical switches 131, respectively.

  Hereinafter, the configuration of the switch unit 130 will be described in more detail. FIG. 3 is a top view of the switch unit 130 according to the present embodiment. The four optical switches 131 are provided in the PLC (substrate) 150. The four common ports 132 are provided on the first end surface 151 of the PLC 150, and the 32 branch ports 133 are provided on the second end surface 151 that faces the first end surface 151 of the PLC 150. A plurality of electrical wirings 155 that are electrically connected to a heater included in the optical switch 131 are provided inside the PLC 150, and the electrical wiring 155 extends along the upper surface of the substrate 151. The electrical wiring 155 includes at least a power supply line for supplying power to the heater and a ground line for connecting the heater to the ground. The electrical wiring 155 is connected to a plurality of electrodes 156 exposed to the outside of the PLC 150, and the electrodes 156 are connected to the third end face 153 and the second end face 153 adjacent to the first end face 151 and the second end face 152 of the PLC 150. 4 in the vicinity of the end face 154.

  As shown in FIG. 3, the plurality of electrodes 156 are provided so as to form a dense group every few, and the surface of the PLC 150 is recessed on the upper surface of the area including the periphery of the PLC 150. An opening 160 to be formed is provided. The electrode 156 is exposed to the outside of the PLC 150 at the opening 160. The number of electrodes 156 included in each group can be arbitrarily determined according to the arrangement of the electrical wiring 155. In the present embodiment, 1 to 16 electrodes 156 are included in one group. For example, one opening 150 may be configured to include a group in which the pitch between the centers of adjacent electrodes 156 is 500 μm or less.

  FIG. 4A is a top view of the PLC 150. Here, for simplification, a configuration including three electrodes 156 is shown, but the number of electrodes 156 included in the opening 160 is arbitrary. In FIG. 4A, the electric wiring 155 exists inside the PLC 150 and is therefore indicated by a broken line. 4B is a cross-sectional view taken along line AA in FIG. 4A, and FIG. 4C is a cross-sectional view taken along line BB in FIG. 4A. The PLC 150 includes a basic substrate 157 provided with an electric wiring 155 on the upper surface, and an insulating film 158 covering the electric wiring 155 and the basic substrate 157. An opening 160 is provided on the upper surface of the PLC 150, and an electrode 156 that is electrically connected to the electric wiring 155 is provided in the opening 160. In this embodiment, the electrode 156 is formed by exposing a part of the electric wiring 155, but a conductive layer (for example, gold plating) may be further provided on the surface of the electrode 156. The base substrate 157 is formed using silicon or the like, and includes a core and a clad that form an optical waveguide of the PLC. In order to reduce the size of the PLC 150, the base substrate 157 desirably has a high relative refractive index difference Δ (for example, 1.5% or more). The insulating film 158 is an insulating layer coated on the electric wiring 155 and the base substrate 157 in order to prevent the electric wiring 155 from being oxidized or short-circuited. In this embodiment, although not limited to these specific numerical values, the width W of the electrodes 156 is about 150 μm, and the pitch between the centers of the adjacent electrodes 156 is about 250 μm. In this embodiment, the basic substrate 157 and the insulating film 158 are provided as separate layers, but may be provided as a single layer in which the optical waveguide and the electrical wiring 155 are formed.

  The opening 160 is provided in a region including the electrode 156 and the third end surface 153 (or the fourth end surface 154) of the PLC 150. A part of the PLC 150 in the thickness direction is removed from the upper surface, and the electrode 156 is removed. It is formed by exposing. By using reactive ion etching, the electrode 156 is not removed, and only the base substrate 157 and the insulating film 158 around the electrode 156 are removed, so that the opening 160 can be easily formed.

  In the opening 160, the upper surface of the PLC 150 (the surface on the side where the electrode 156 is disposed) other than the region where the electrode 156 is disposed is recessed with respect to the upper surface of the electrode 156 (the surface on the side not in contact with the PLC 150). Is (ie, concave). That is, d <0 with respect to the height d (upward direction is positive) of the upper surface of the PLC 150 with respect to the surface including the upper surface of the electrode 156. Here, the direction in which the electrode 156 is formed with respect to the upper surface of the base substrate 157 is defined as the upward direction. By making the PLC 150 and the electrode 156 have such a height relationship, as will be described in detail later, conduction failure can be suppressed and damage to the surface of the PLC 150 can be suppressed. In this embodiment, the insulating film 158 remains on the upper surface of the PLC 150 in the opening 160, but the insulating film 158 is completely removed by reactive ion etching or the like, and the base substrate 157 is partially removed in the thickness direction. However, the upper surface of the PLC 150 in a region other than the region where the electrode 156 is disposed may be configured to be located below the lower surface of the electrode 156.

  FIG. 5A is a top view of the FPC 200 as a wiring board connected to the PLC according to the present embodiment. Here, for simplification, a configuration in which three electrodes 203 are provided at both ends is shown, but the number of electrodes 203 included in the FPC 200 is arbitrary. 5B is a cross-sectional view taken along the line CC in FIG. 5A, and FIG. 5C is a cross-sectional view taken along the line DD in FIG. 5A. The FPC 200 is formed on the substrate 201, the electric wiring 202 provided on the upper surface of the substrate 201, the cover lay 204 that covers the upper surface of the electric wiring 202, and the portion of the electric wiring 202 that is not covered by the cover lay 204. The electrode 203 is provided. The substrate 201 and the coverlay 204 are formed using an insulating material such as polyimide, and support and protect the electric wiring 202 and the electrode 203. Since the polyimide substrate 201 is soft, a reinforcing film 205 formed of glass fiber or the like is provided in a region located below the electrode 203 on the lower surface of the substrate 201 to reinforce the electrode 203 from the back side. . The electrical wiring 202 is formed using a conductive material such as copper, and the electrode 203 is formed by plating a part (for example, both ends) of the electrical wiring 202 with a conductive material such as gold. By connecting the electrode 156 of the PLC 150 and the electrode 203 of the FPC 200, the electrical wiring 155 of the PLC 150 and the electrical wiring 202 of the FPC 200 can be made conductive. Further, by connecting a control unit to the electrode 203 of the FPC 200, the control unit and the PLC 150 are electrically connected, and the control unit can control the switch unit 130 included in the PLC 150. In this embodiment, although not limited to these specific numerical values, the width L of the electrode 203 is about 150 μm, and the pitch between the centers of the adjacent electrodes 203 is about 250 μm.

  FIGS. 6A, 6 </ b> B, and 6 </ b> C are cross-sectional views illustrating a state before and after connecting the PLC 150 and the FPC 200 with the ACF 300. 6A, 6B and 6C are cross sections of the PLC 150 taken along the line AA in FIG. 4A and the cross section of the FPC 200 taken along the line CC in FIG. 5A. The combined state is shown. The ACF 300 includes a film-like adhesive 301 and conductive particles 302 mixed in the adhesive 301. As the adhesive 301, for example, a thermosetting epoxy resin or an acrylic resin can be used. As the conductive particles 302, for example, metal particles or particles formed by coating a conductive layer on a resin can be used. It is preferable that the outermost periphery of the conductive particles 302 is covered with an insulating layer configured to be broken by pressure. In that case, when the conductive particles 302 are sandwiched between the electrode 156 of the PLC 150 and the electrode 203 of the FPC 200, the insulating layer is broken by pressure and conductivity is generated, so that only the conductive between the electrode 156 and the electrode 203 is conducted. In addition, insulation is maintained in other portions. As a result, the occurrence of a short circuit can be more effectively suppressed. As an adhesion means between the PLC 150 and the FPC 200, an anisotropic conductive paste (ACP) containing conductive particles in a paste adhesive may be used in place of the film-like ACF300. The configuration of the form and the connection method are the same.

  When connecting the PLC 150 and the FPC 200, first, as shown in FIG. 6A, the upper surface of the PLC 150 (the surface on the side where the electrode 156 is provided) and the upper surface of the FPC 200 (the side on which the electrode 203 is provided). The electrode 156 and the electrode 203 are aligned with each other. Thereafter, the ACF 300 is sandwiched between the PLC 150 and the FPC 200, and pressure is applied in a direction in which the PLC 150 and the FPC 200 approach while heating. As a result, the PLC 150 and the FPC 200 are bonded by the ACF 300 as shown in FIG.

  In the present embodiment, in the opening 160, the upper surface of the PLC 150 in a region where the electrode 156 is not disposed is recessed with respect to the upper surface of the electrode 156 (that is, concave or d <0). Specifically, in the region between the two electrodes 156 adjacent to each other (in the region around the electrode 156 in which another electrode 156 does not exist next to it), the upper surface of the PLC 150 is higher than the upper surface of the electrode 156. It is depressed. With such a configuration, it is possible to suppress the occurrence of poor conduction between the electrode 156 and the electrode 203 even at the time when the positional deviation occurs between the PLC 150 and the FPC 200, and at the same time, the insulating film 158 (or The pressure applied to the base substrate 157) from the electrode 203 via the conductive particles 302 is reduced. As shown in FIG. 6B, even when a positional deviation occurs between the PLC 150 and the FPC 200, the conductive particles 302 are sandwiched between the electrode 156 and the electrode 203 (that is, Since the conductive particles 302 are in contact with the electrode 156 and the electrode 203 at the same time, electrical conduction is ensured. On the other hand, since the upper surface of the PLC 150 is recessed with respect to the upper surface of the electrode 156, another conductive particle 302 having the same or smaller particle diameter than the conductive particle 302 is formed between the insulating film 158 and the electrode 203. There is no contact with both at the same time. In this state, since the conductive particles 302 do not transmit the pressure from the electrode 203 to the insulating film 158 provided on the upper surface of the PLC 150, damage to the insulating film 158 can be suppressed. That is, when the conductive particle 302 having the same or smaller particle diameter than the conductive particle 302 sandwiched between the electrode 156 and the electrode 203 is positioned between the insulating film 158 and the electrode 203, the insulating particle Generation of force applied to the film 158 can be prevented.

  A large number of conductive particles 302 are included in the connection portion between the PLC 150 and the FPC 200, but the size of the conductive particles 302 varies, and not all the conductive particles 302 have the same particle diameter. However, the conductive particles 302 are considered to have the highest probability of having an average particle diameter R. Therefore, in many cases, the particle diameter of the conductive particles 302 positioned between the insulating film 158 and the electrode 203 is the same as the particle diameter of the conductive particles 302 sandwiched between the electrode 156 and the electrode 203. It will be smaller than that. Therefore, as long as at least the upper surface of the PLC 150 is recessed with respect to the upper surface of the electrode 156 (that is, it is concave or d <0), the entire connecting portion between the PLC 150 and the FPC 200 is the insulating film 158. The pressure applied to the insulating film 158 can be reduced, and damage to the insulating film 158 can be suppressed.

In order to suppress damage to the insulating film 158 more reliably, d is preferably as small as possible (that is, the absolute value of d is large). For example, as shown in FIG. 6C, when the maximum particle diameter of the conductive particles 302 including variation is R _max and the minimum particle diameter is R _min , the height of the upper surface of the PLC 150 with respect to the upper surface of the electrode 156 is set. For d (upward is positive), it is preferable that | d |> R _max −R _min . By using such d, the conductive particle 302 having the minimum particle diameter R _min is positioned between the electrode 156 and the electrode 203, and at the same time, the maximum particle diameter R _max is set between the insulating film 158 and the electrode 203. Even when the conductive particles 302 having the conductive particles 302 are located, the conductive particles 302 do not apply pressure to the insulating film 158. Therefore, damage to the insulating film 158 can be more reliably suppressed.

  When the upper surface of the PLC 150 (insulating film 158) is recessed with respect to the upper surface of the electrode 156 (that is, d <0), the side surface of the electrode 156 is exposed. If wire bonding is performed in this state as in the prior art, the side surfaces of the electrode 156 remain exposed even after connection, and oxidation of the electrode 156 and the layer under the electrode 156 may occur. On the other hand, in this embodiment, since the PLC 150 and the FPC 200 are connected using the ACF 300, the side surface of the electrode 156 is covered with the adhesive 301 of the ACF 300 after the connection, so the side surface of the electrode 156 is not exposed, and the electrode 156 And oxidation of the layer under the electrode 156 can be reduced.

  The width L of the electrode 203 of the FPC 200 and the width W of the electrode 156 of the PLC 150 can be arbitrarily set, but preferably L ≧ W. As a result, even when the demand for reducing the size of the PLC 150 as described above (decreasing W) is met, a sufficient contact area between the electrode 203 and the electrode 156 is ensured and the connectivity is improved. Can do. On the contrary, when L <W as in the technique described in Patent Document 1, if the size of the PLC 150 is reduced, the FPC 200 needs to be further reduced, so that the contact area between the electrode 203 and the electrode 156 Becomes smaller and the connectivity deteriorates. In addition, errors occur in the width, pitch, and alignment of the electrodes 203 and 156. Therefore, it is more preferable that L ≧ W + X using the maximum error X. By setting L and W in this way, even when the maximum error X occurs, the electrode 203 and the electrode 156 can be brought into contact with each other with the maximum area. Specifically, the maximum error may be 10% and L ≧ 1.1W.

  FIGS. 7A and 7B are cross-sectional views showing a state before and after connecting the PLC 150 and the FPC 200 by the ACF 300. 7A and 7B show a state in which the cross section of the PLC 150 taken along the line BB in FIG. 4A and the cross section of the FPC 200 taken along the line DD in FIG. 5A are combined. Show. Since a general FPC is provided with a coverlay having a thickness (about 50 μm in this embodiment) for protecting an electrode, the coverlay may interfere with the PLC when the FPC is directly bonded to the PLC. is there. On the other hand, in the present embodiment, the opening 160 in which the electrode 156 is disposed is provided in a region including the end face 153 of the PLC 150. Therefore, the upper surface of PLC 150 is recessed with respect to the upper surface of electrode 156 in the region between electrode 156 and end surface 153. With such a configuration, the FPC 200 can be connected to the PLC 150 such that the coverlay 204 is positioned outside the end face 153 of the PLC 150 as shown in FIG. As a result, the coverlay 204 does not interfere with the PLC 150 even when the PLC 150 and the FPC 200 are connected.

(First embodiment)
A sample in which the PLC 150 and the FPC 200 having the configuration of the first embodiment were connected was manufactured, and a continuity test was performed. ACF300 was sandwiched between PLC150 and FPC200, and a sample was produced by pressure bonding under conditions of 180 ° C., 3 MPa, and 20 seconds. When the continuity test of the sample was performed after the connection, it was confirmed that the continuity was established between the electrode 156 and the electrode 203. Furthermore, a pressure cooker test (120 ° C., humidity 100%, 20 hours) for measuring resistance to high-temperature and high-humidity conditions, and a heat shock test (−40 ° C.˜ 85 ° C., 500 cycles). When conducting the continuity test of the sample after performing these tests, there was no change from the resistance value before the test, and there was no peeling between the PLC 150 and the FPC 200. From the above, it was confirmed that the configuration according to the first embodiment has sufficient conductivity and resistance.

(Second Embodiment)
FIG. 8 is a top view of the switch unit 130 according to the present embodiment. In the first embodiment, as shown in FIG. 3, an opening 160 is provided for each group of adjacent electrodes 156. On the other hand, in this embodiment, as shown in FIG. 8, the opening portion includes all the electrodes 156 arranged along one end surface (third end surface 153 or fourth end surface 154) of the PLC 150. 160 is provided.

  When the FPC 200 is connected to the PLC 150 by providing the opening 160 as in the present embodiment, all the electrodes provided along the end surface can be obtained by performing connection work once on one end surface of the PLC 150. 156 connections can be made. Therefore, the time required for the connection work can be reduced as compared with the case where the opening 160 is provided for each group of the electrodes 156 as in the first embodiment.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 100 Switch apparatus 110 Housing | casing 120 Splitter part 121 Optical splitter 130 Switch part 131 Optical switch 140 Shuffle fiber array 150 Planar optical waveguide board (PLC)
151, 152, 153, 154 End face 155 Electrical wiring 156 Electrode 157 Base substrate 158 Insulating layer 160 Opening 200 Flexible printed wiring board (FPC)
201 Substrate 202 Electric wiring 203 Electrode 204 Coverlay 205 Reinforcing film 300 Anisotropic conductive film (ACF)
301 Adhesive 302 Conductive Particle

Claims (10)

An optical module comprising a wiring board and a planar optical waveguide substrate connected to the wiring board,
The wiring board is
A first substrate;
First electrical wiring provided on the first substrate;
A first electrode provided on the first substrate and electrically connected to the first electrical wiring;
With
The planar optical waveguide substrate is:
A second substrate;
An optical waveguide provided inside the second substrate;
A second electrical wiring provided inside the second substrate;
An opening formed by recessing a part of the surface of the second substrate;
A second electrode provided on the second substrate in the opening and electrically connected to the electrical wiring;
With
The surface of the second substrate other than the region where the second electrode is disposed in the opening is recessed with respect to the surface of the second electrode,
The optical module, wherein the first electrode and the second electrode are electrically connected in the opening.   The optical module according to claim 1, wherein the wiring board and the planar optical waveguide substrate are connected via an anisotropic conductive film (ACF) or an anisotropic conductive paste (ACP).   The optical module according to claim 1, wherein a width L of the first electrode is equal to or greater than a width W of the second electrode. At least two second electrodes are provided,
The opening includes the at least two second electrodes;
The surface of the second substrate in a region between the at least two second electrodes is recessed with respect to the surface of the at least two second electrodes. The optical module of any one of -3. The opening is formed in a region including a part of an end surface adjacent to the surface of the second substrate;
The surface of the second substrate in a region between the second electrode and a part of the end face is recessed with respect to the surface of the second electrode. 5. The optical module according to any one of 4 above.   6. The heater according to claim 1, further comprising a heater provided in the vicinity of the optical waveguide in the second substrate and electrically connected to the second electrical wiring. The optical module as described in. A substrate,
An optical waveguide provided inside the substrate;
Electrical wiring provided inside the substrate;
An opening formed by recessing a part of the surface of the substrate;
An electrode provided on the substrate in the opening and electrically connected to the electrical wiring;
With
The planar optical waveguide substrate, wherein the surface of the substrate other than the region where the electrode is disposed in the opening is recessed with respect to the surface of the electrode. At least two of the electrodes are provided,
The opening includes the at least two electrodes;
The planar optical waveguide substrate according to claim 7, wherein the surface of the substrate in a region between the at least two electrodes is recessed with respect to the surface of the at least two electrodes. The opening is formed in a region including a part of an end surface adjacent to the surface of the substrate;
The planar optical waveguide substrate according to claim 7 or 8, wherein the surface of the substrate in a region between the electrode and a part of the end surface is recessed with respect to the surface of the electrode.   The planar optical waveguide according to any one of claims 7 to 9, further comprising a heater provided in the vicinity of the optical waveguide in the substrate and electrically connected to the electrical wiring. substrate.