JP2009008764A - Photoelectric transducer and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoelectric transducer in which the covering of an electrode for mounting by a resin for clad is suppressed, and to provide a method of manufacturing the photoelectric transducer. <P>SOLUTION: The photoelectric transducer 1 is provided with a substrate 3 on which the electrode 36 for mounting is formed for mounting components around a waveguide 31 which transmits an optical signal. A resin material 35 which sheds the liquid resin 31b' for clad before hardened is coated around a groove 32 for forming waveguide on the substrate 3. Thus, the coated resin material 35 blocks the flow of the liquid resin 31b' for clad and the covering of the electrode 36 for mounting with a resin 31b' is suppressed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a photoelectric conversion device and a method for manufacturing the same.

  2. Description of the Related Art Conventionally, there is an optoelectric conversion device including a substrate on which mounting electrodes for component mounting are formed around a waveguide that propagates an optical signal (see Reference 1).

  By the way, in the step of forming the waveguide on the substrate, the waveguide forming groove 61 and the mounting electrode 62 are formed on the substrate 60 as shown in FIG. 9A, and the waveguide is formed as shown in FIG. A liquid clad resin (epoxy) 63 is applied to the waveguide forming groove 61, and the core groove 65 is embossed by a mold 64 as shown in FIGS. After the mold release, the waveguide is formed by filling the core groove 65 with the core resin, although not specifically shown.

  In the mold transfer method such as emboss molding, it is necessary to make a fluid state (liquid state) once in order to transfer the mold in the course of the process regardless of whether the resin material is thermosetting or thermoplastic. is there.

For this reason, the liquid cladding resin 63 overflows on the substrate 60 by the mold pressure of the mold 64 as shown in FIG. 10 during the embossing of FIG. 9D (see the two-dot chain line a), When the mounting electrode 62 is provided around the waveguide forming groove 61, if the mounting electrode 62 is covered with the cladding resin 63, bonding failure occurs during component mounting. Need to be removed.
JP-A-10-170769

  However, when the clad resin 63 is a thermosetting resin typified by epoxy or the like, it is difficult to remove only an arbitrary portion because it has high chemical and mechanical resistance. As a countermeasure, the resin was removed by the excimer laser LB or the like as shown in FIG. 9 (f), but the influence of the excimer laser LB or the like affected the mounting electrode 62, and the adhesion of the mounting electrode 62 was reduced. There was a problem that decreased.

  The present invention has been made to solve the above-described problems, and provides a photoelectric conversion apparatus and a method for manufacturing the photoelectric conversion apparatus that can prevent a mounting electrode from being covered with a cladding resin.

  In order to solve the above-mentioned problems, the photoelectric conversion device of the present invention is a photoelectric conversion device including a substrate on which a mounting electrode for component mounting is formed around a waveguide that propagates an optical signal. The substrate is coated with a resin material that repels the liquid clad resin before curing around the waveguide forming groove of the substrate.

  As in claim 2, the resin material is preferably a photocurable resin.

  According to a third aspect of the present invention, the resin material may have a configuration in which a mounting portion is opened and coated on a mounting electrode.

  According to a fourth aspect of the present invention, the resin material may be coated on the substrate between the mounting electrodes.

  A method for manufacturing a photoelectric conversion device according to the present invention is a method for manufacturing a photoelectric conversion device including a substrate on which a mounting electrode for component mounting is formed around a waveguide that propagates an optical signal. After the step of forming the waveguide forming groove, a resin material that repels the liquid clad resin before curing is coated around the waveguide forming groove, and then the liquid forming resin is applied to the waveguide forming groove. After coating, the core groove is embossed, and the core groove is filled with a core resin to form a waveguide.

  According to a sixth aspect of the present invention, a step of opening a mounting pattern portion of the mounting electrode after coating the resin material on the mounting electrode can be provided.

  According to a seventh aspect of the present invention, after the waveguide is formed, a step of peeling the resin material at a predetermined position can be provided.

  According to the photoelectric conversion device and the manufacturing method thereof of the present invention, a resin material that repels the liquid clad resin before curing is coated around the waveguide forming groove so that the liquid clad resin is applied or the core is coated. When embossing the groove, the surplus liquid clad resin overflows from the waveguide forming groove onto the substrate, and the coating resin material prevents the liquid clad resin from flowing. It becomes possible to prevent the clad resin from being covered.

  According to the second aspect, by using the photocurable resin, the coating resin material can be patterned by a simple process as compared with the thermosetting resin.

  According to claim 3 and claim 6, since the mounting portion is not coated with a resin material, there is no hindrance to component mounting, and at the time of reflow of component mounting in a later process, the coating resin material is mounted with solder or the like. It plays a role of a solder resist that suppresses the flow on the electrode.

  According to the fourth aspect, since the dielectric constant between the mounting electrodes can be controlled by changing the coating width and thickness of the coating resin material, the characteristics of the high-frequency device can be improved.

  According to the seventh aspect, the portion where the mounting electrode is not covered with the cladding resin can be peeled off from the substrate with an excimer laser or the like, if necessary. The electrode is not affected by excimer laser or the like.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  7 and 8 show the basic structure of the photoelectric conversion device 1. The photoelectric conversion device 1 includes a light emission side photoelectric conversion unit 1A, a light reception side photoelectric conversion unit 1B, and the conversion units 1A, 1A, And an external waveguide 9 that optically connects 1B. In FIG. 7, the vertical direction in FIG. 7 is referred to as the vertical direction, the direction orthogonal to the paper surface is referred to as the horizontal direction, and the right side of FIG. For the light-receiving side photoelectric conversion unit 1B, the left side in FIG.

  The light emission side photoelectric conversion unit 1A includes a wiring board 2 and a mount board 3 mounted on the upper surface of the wiring board 2 at a predetermined interval. On the lower surface 3a of the mount substrate 3, a light emitting element 4A for converting an electric signal into an optical signal and an IC substrate 5A on which an IC circuit 50A for transmitting the electric signal to the light emitting element 4A is formed are mounted. ing. In the mount substrate 3, a waveguide 31 that is optically coupled to the light emitting element 4A is formed.

  As the light emitting element 4A, a VCSEL (Vertical Cavity Surface Emitting Laser) having a size of 300 μm □ in a plan view that emits light upward from the upper surface is employed. The IC substrate 5A is a driver IC that drives the VCSEL, and is disposed in the vicinity of the light emitting element 4A. The light emitting element 4A and the IC substrate 5A are connected to an unillustrated wiring pattern (the light emitting element 4A is a mounting electrode 36 to be described later) formed on the lower surface 3a of the mount substrate 3 with gold bumps 11 (see FIG. 8). Has been. As the light emitting element 4A, an LED or the like can also be adopted. However, the LED or the like has no directivity, and the ratio of optical coupling to the waveguide 31 is small. In some cases, it is advantageous in terms of low price.

  The mount substrate 3 has a rectangular shape extending in the front-rear direction in plan view, and is connected to an unillustrated wiring pattern formed on the upper surface of the wiring substrate 2 by solder bumps 10. The mount substrate 3 needs to be rigid in order to avoid the influence of heat during mounting and the influence of stress due to the use environment. In the case of optical transmission, since light transmission efficiency from the light emitting element to the light receiving element is required, it is necessary to mount the optical element with high accuracy and to suppress position fluctuation during use as much as possible. For this reason, a silicon substrate is employed as the mount substrate 3. The mount substrate 3 is preferably made of a material having a linear expansion coefficient close to that of the light emitting element 4A, and may be made of a compound semiconductor such as GaAs of the same system as the VCSEL material other than silicon.

  The mount substrate 3 is provided with a 45 ° mirror 33 for bending the optical path by 90 ° at a position directly above the light emitting element 4A.

  The waveguide 31 extends forward from the 45 ° mirror 33 and has an end face that is substantially flush with the front end face of the mount substrate 3. As shown in FIG. 8, the waveguide 31 includes a core 31 a having a substantially square cross section and a clad 31 b that covers the core 31 a from the periphery, and is inside the waveguide forming groove 32 formed on the mount substrate 3. It is arranged.

  The sizes of the core 31a and the clad 31b are determined giving priority to light efficiency from the distance from the light emitting element 4A to the waveguide 31, the divergence angle of the light emitting element 4A, and the size of the light receiving element 4B described later.

  For example, in a general VCSEL used for high-speed transmission of 5 to 10 Gbps or more and a PD (photodiode) which is a light receiving element 4B, the emission diameter of the VCSEL is 5 to 10 μm and the divergence angle is about 20 °. Since the light receiving diameter is about 60 μm, the size of the core 31 a is 40 μm □, and the thickness of the clad 31 b is 2 to 10 μm.

  At the front end of the mount substrate 3, a pair of left and right resin structures 6 spaced apart from each other with the waveguide 31 interposed between the lower surface 3a and an adapter 7A are attached. An optical connector 8A provided at the end of the external waveguide 9 is detachably attached to the adapter 7A, whereby the external waveguide 9 is optically coupled to the waveguide 31 of the mount substrate 3. It has become so.

  The external waveguide 9 is a flexible film having a predetermined width, and although not specifically illustrated, the core is placed on the lower cladding, and the core is covered with the upper cladding. It has become.

  When the optical connector 8A is attached to the adapter 7A, the position of the core 31a of the waveguide 31 of the mount substrate 3 matches the position of the core of the external waveguide 9.

  Since the basic configuration of the light-receiving side photoelectric conversion unit 1B is the same as that of the light-emitting side photoelectric conversion unit 1A, detailed description thereof is omitted. The light emitting side photoelectric conversion unit 1A differs from the light receiving element 4B that converts an optical signal into an electric signal on the lower surface 3a of the mounting substrate 3, and an IC circuit for receiving an electric signal from the light receiving element 4B. The IC board 5B on which 50B is formed is mounted. PD is adopted as the light receiving element 4B, and the IC substrate 5B is a TIA (Trans-impedance Amplifier) element that performs current / voltage conversion. In addition, an amplifier element may be mounted on the mount substrate 3.

  Next, the manufacturing method of the photoelectric conversion apparatus 1 of this invention is demonstrated based on FIG. The photoelectric conversion device 1 can separately manufacture the light emission side photoelectric conversion unit 1A and the light reception side photoelectric conversion unit 1B, and the manufacturing method thereof is the same. A method for manufacturing the side photoelectric conversion unit 1A will be described. In FIG. 5, the lower surface 3a of the mount substrate 3 is displayed upward for convenience of drawing.

  First, a method of forming the waveguide 31 and the 45 ° mirror (45 ° inclined surface) 33 on the mount substrate 3 will be briefly described with reference to FIG. Normally, a plurality of mount substrates 3 are simultaneously formed using a silicon wafer (silicon substrate), and finally the silicon wafer is cut to separate the mount substrates 3 into pieces. The mounting substrate 3 will be described.

  First, as shown in FIG. 5A, the waveguide forming groove 32 and the 45 ° mirror 33 are formed on the mount substrate 3. These are formed by anisotropic etching utilizing the difference in etching rate of silicon crystals.

Next, a mounting electrode 36 for mounting the light emitting element 4 </ b> A is formed on the mount substrate 3.
The electrode 36 is patterned by depositing gold on the mount substrate 3. At this time, gold (high reflectivity) is simultaneously deposited on the 45 ° mirror 33. Although depending on the wavelength used, it is possible not to deposit gold on the 45 ° mirror 33.

  Then, as in the step of FIG. 5B, mounting is performed on the mount substrate 3 around the waveguide forming groove 32 along the upper side of the waveguide forming groove 32 in the first embodiment of FIG. A resin material (hereinafter sometimes referred to as a coating resin material) 35 that repels the liquid clad resin 31b ′ before curing is coated (so-called water-repellent coating) so as not to cover the electrode 36 for curing, Cured by light curing. Thereafter, a liquid clad resin (epoxy... Lower clad resin) 31 b ′ is applied to the waveguide forming groove 32.

  Next, as shown in FIGS. 5C and 5D, the core groove 37 is embossed with a mold 39 (for example, 120 ° C. for 30 minutes), and then released as shown in FIG. 5E. Thereafter, although not specifically shown, the core groove 37 is filled with the core resin to form the core 31a, and finally the upper clad resin is applied on the core 31a to form the clad 31b. Thus, the waveguide 31 is formed.

  In addition, after the mold release step shown in FIG. 5E, that is, after the waveguide 31 is formed, an excimer laser or the like may be used as necessary at a portion where the mounting electrode 36 is not covered with the cladding resin 31b ′. Thus, the coating resin material 35 can be peeled from the mount substrate 3, and in this case, the mounting electrode 36 is not affected by an excimer laser or the like.

  When the light emitting element 4A is mounted on the mount substrate 3, gold bumps 11 are formed on the light emitting element 4A by stud bump bonding, the mount substrate 3 and the light emitting element 4A are heated to 200 ° C., and the light emitting element 4A is mounted on the mount substrate. 3 is mounted on the mounting electrode 36 by ultrasonic bonding or the like. The IC substrate 5A is mounted on the mount substrate 3 simultaneously with the light emitting element 4A.

  In the first embodiment of FIG. 1, as described above, the liquid clad resin 31b ′ before curing is applied so as not to cover the mounting electrode 36 along the upper side of the waveguide forming groove 32 of the mount substrate 3. The resin material 35 to be repelled is coated.

  According to the first embodiment, by coating the resin material 35 that repels the liquid clad resin 31b ′ before curing along the upper side of the waveguide forming groove 32, the liquid clad resin 31b ′ can be applied or When emboss molding of the core groove 37 is performed, an excess of the liquid clad resin 31 b ′ overflows from the waveguide forming groove 32 onto the mount substrate 3. Since the flow of 31b ′ is prevented, it is possible to prevent the mounting electrode 36 from being covered with the clad resin 31b ′ after being cured from the liquid state.

  Therefore, since the mounting electrode 36 is not covered with the clad resin 31b ′, no bonding failure occurs when the light emitting element 4A (component) is mounted.

  FIG. 2 shows the second embodiment, which is different from the first embodiment in a liquid before curing so as to cover only the mounting electrode 36 located around the waveguide forming groove 32 of the mount substrate 3. A resin material 35 that repels the clad resin 31b 'is coated.

  In this case, the coating resin material 35 is coated on the mounting electrode 36 by opening the mounting portion 35a of the mounting electrode 36 as shown in FIG. Specifically, in the step of FIG. 5B, after the resin material 35 is coated on the mounting electrode 36, the mounting portion 35a of the mounting electrode 36 is opened (that is, the coating resin material 35 is removed). ) Add a process.

  According to the second embodiment, since the coating resin material 35 opens the mounting portion 35a and coats the mounting electrode 36, the liquid clad resin 31b 'is applied or the core groove is embossed. Even if the surplus liquid clad resin 31b ′ overflows from the waveguide forming groove 32 onto the mount substrate 3 (see the two-dot chain line a in FIG. 2A), the resin material 35 as the coating material remains. Since the flow of the liquid clad resin 31b ′ is prevented, it is possible to suppress the mounting electrode 36 from being covered with the clad resin 31b ′ after being cured from the liquid state.

  In addition, since the mounting portion 35a is not coated with the resin material 35, there is no hindrance to the mounting of the light emitting element 4A, and at the time of reflowing the mounting of the light emitting element 4A in a later process, the coating resin material 35 is mounted with solder or the like Thus, it plays the role of a solder resist that suppresses the flow on the electrode 36.

  FIG. 3 shows a modification of the second embodiment. Instead of coating the resin material 35 so as to cover only the mounting electrode 36 as in the second embodiment, the upper side of the waveguide forming groove 32 is shown in FIG. A resin material 35 is coated in a substantially square shape so as to cover the mounting electrode 36 and the mounting substrate 3 around it. Also in this case, the mounting portion 35a of the mounting electrode 36 is opened.

  FIG. 4 shows the third embodiment, which is different from the first embodiment in that a resin material 35 that repels the liquid clad resin 31 b ′ before curing is coated on the mount substrate 3 between the mounting electrodes 36. Is.

  According to the third embodiment, since the dielectric constant between the mounting electrodes 36 can be controlled by changing the coating width W and thickness of the coating resin material 35, the characteristics of the high-frequency device can be improved.

  As the thermosetting resin, the resin material 35 that repels the liquid clad resin 31b ′ described above, that is, the coating resin material 35 is amorphous (trade name Teflon (registered trademark) AF manufactured by 3M), fluorine coating material (Asahi Glass). There is a product name “CYTOP” manufactured by the company, and a silicon-based coating material (product name “FRESERA DA100” manufactured by Matsushita Electric Works).

  Examples of the photocurable resin include a fluorine-based coating material.

  The thermosetting resin is used in a manufacturing method by a lift-off method, and after forming a mounting electrode 36 on the mount substrate 3 as shown in FIG. 6A, a resist 45 is applied as shown in FIG. 6B. Then, as shown in FIG. 6C, the resist on the mounting electrode 36 is removed by resist patterning (exposure / development), and the coating resin material is applied on the mounting electrode 36 as shown in FIG. 6D. As shown in FIG. 6E, the coating resin material 35 of the coated mounting electrode 36 is left, and the resist around the resin is peeled off to cover the mounting electrode 36 as shown in FIG. The material 35 can be coated.

  The photo-curable resin is used in a manufacturing method by UV patterning, and after forming the mounting electrode 36 on the mount substrate 3 as shown in FIG. 6 (f), the coating is applied as shown in FIG. 6 (g). By coating the resin material 35 and removing the coating resin material 35 by patterning (exposure / development) as shown in FIG. 6H, the resin material 35 can be coated so as to cover the mounting electrode 36. .

  Therefore, by using a photo-curing resin as the coating resin material 35, the coating resin material 35 can be patterned by a simple process as compared with the thermosetting resin.

BRIEF DESCRIPTION OF THE DRAWINGS It is the photoelectric conversion apparatus which concerns on 1st Embodiment of this invention, (a) is a top view, (b) is the AA line expanded sectional view of (a). It is the photoelectric conversion apparatus which concerns on 2nd Embodiment, (a) is a top view, (b) is the BB line expanded sectional view of (a). It is a top view of the modification of 2nd Embodiment. It is a top view of the photoelectric conversion apparatus concerning a 3rd embodiment. (A)-(e) is process drawing which forms a waveguide in the board | substrate of the photoelectric conversion apparatus which concerns on 1st Embodiment of this invention. (A)-(e) is process drawing which shows the lift-off method, (f)-(h) is process drawing which shows UV patterning method. It is a side view of the basic structure of the photoelectric conversion apparatus which concerns on this invention. (A) is a side view of a mount substrate, (b) is the sectional view on the AA line of (a). (A)-(f) is process drawing which forms a waveguide in the conventional board | substrate. It is a top view in the state where resin for liquid clad overflowed on the substrate.

Explanation of symbols

1 Photoelectric conversion device 3 Mount substrate (substrate)
31 Waveguide 31a Core 31b Clad 31b ′ Liquid clad resin 32 before curing 32 Waveform forming groove 33 45 ° mirror 35 Resin material that repels liquid clad resin (coating resin material)
35a Mounting part 36 Mounting electrode 37 Core groove 39 Mold 4A Light emitting element (optical element)

Claims (7)

A photoelectric conversion device comprising a substrate on which a mounting electrode for component mounting is formed around a waveguide that propagates an optical signal,
A photoelectric conversion device, wherein a resin material that repels a liquid clad resin before curing is coated around a waveguide forming groove of the substrate.   The photoelectric conversion apparatus according to claim 1, wherein the resin material is a photocurable resin.   The photoelectric conversion apparatus according to claim 1, wherein the resin material is coated on the mounting electrode by opening a mounting portion.   The photoelectric conversion apparatus according to claim 1, wherein the resin material is coated on a substrate between mounting electrodes. A method of manufacturing a photoelectric conversion device comprising a substrate on which a mounting electrode for component mounting is formed around a waveguide that propagates an optical signal,
After the step of forming the waveguide forming groove on the substrate, the periphery of the waveguide forming groove is coated with a resin material that repels the liquid clad resin before curing, and then the waveguide forming groove is liquid clad resin. A method for manufacturing an optoelectric conversion device, comprising: embossing a core groove after coating and filling a core resin into the core groove to form a waveguide.   6. The method of manufacturing a photoelectric conversion device according to claim 5, further comprising a step of opening a mounting pattern portion of the mounting electrode after coating the resin material on the mounting electrode.   6. The method of manufacturing an optoelectric conversion device according to claim 5, further comprising a step of peeling the resin material at a predetermined position after forming the waveguide.

Images