JP2016027351A - Connection structure between lenses and photoelectric composite wiring module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that optical coupling efficiency is significantly reduced due to angle deviation between two lenses so that an optical signal cannot be transmitted.SOLUTION: A connection structure between lenses includes a first lens, a second lens, and elastic bodies on both sides of a back faces of at least one of the first and second lenses.SELECTED DRAWING: Figure 1(a)

Description

  The present invention relates to a connection structure between two lenses, and more particularly to a photoelectric composite wiring module that collectively processes a large-capacity optical signal and a transmission device using the same.

  2. Description of the Related Art In recent years, communication traffic using optical signals has been rapidly developed in the information and communication field, and optical fiber networks have been deployed over long distances of several kilometers or more such as trunk, metro, and access systems. In the future, it will be effective to use optical signals to process large volumes of data without delay even at short distances between transmission devices (several meters to several hundreds of meters) and within devices (several centimeters to several tens of centimeters). Opticalization of transmission between LSIs in an information device such as a router and a server or between an LSI and a backplane is being promoted.

  When constructing a transmission device using optical signals, what is important is how to transmit optical signals simply and efficiently. It is important to efficiently propagate an optical signal from the light emitting element to an optical wiring such as an optical fiber or an optical waveguide, or to efficiently enter an optical signal propagated from the optical transmission path to the light receiving element. In general, in order to improve the optical coupling efficiency between the optical element and the optical transmission line, it is necessary to align the optical element and the optical transmission line with high precision. Considering this, it is necessary to avoid an increase in mounting man-hours and an increase in mounting difficulty due to highly accurate alignment.

  In other words, it is desirable that electrical coupling and optical coupling can be performed at the same time with a simple mounting equivalent to that of a conventional electronic component with only electrical connection without being conscious of using an optical signal. Furthermore, a mounting structure that can achieve high optical coupling efficiency even with such simple mounting is desired.

  For example, in Japanese Patent Application Laid-Open No. 2002-189137 (Patent Document 1), the lead frame of an optical package containing an optical element and the substrate are electrically joined with solder or the like to form the optical element and the substrate. The optical waveguide and the optical waveguide are optically coupled, and electrical connection and optical coupling can be performed simultaneously by conventional electronic component mounting.

JP 2002-189137 A

  However, the above-described conventional technique has the following problems. The optical coupling between the optical element and the optical waveguide uses a collimating optical system using two lenses. This optical system has a large positional displacement tolerance between the two lenses in the direction perpendicular to the optical axis and in the optical axis direction. Therefore, a two-lens structure is also used in this prior art so that a high optical coupling can be obtained even if a positional deviation occurs to some extent by soldering.

  However, this optical system is characterized by a small tolerance for the angular deviation between the lenses. In this structure, there are many dangers that an angle deviation occurs between the lens optical axis on the optical package side and the lens optical axis on the substrate side due to lead frame distortion, solder thickness variation, electrode height variation, and the like. Even if the optical axes are parallel during mounting, there is still a possibility that an angle deviation such as deformation of the lead frame due to external force occurs during use. In other words, the conventional structure has a problem that the optical coupling efficiency is significantly lowered due to the angle shift during mounting and use as described above, and the optical signal cannot be transmitted.

  It is an object of the present invention to have a connection structure that eliminates the angular deviation between two lenses, and a structure that can easily perform electrical connection and optical coupling at the same time and that can ensure high optical coupling efficiency. It is to provide a photoelectric composite module and to provide a transmission device using the same.

  In order to achieve the above object, the present invention is characterized by having elastic bodies on both sides of the back surface of at least one of the two lenses.

Furthermore, in the photoelectric composite wiring module having a structure for performing electrical connection and optical coupling simultaneously,
An optical element, an IC for driving the optical element, a first substrate having a first lens for optical connection between the optical element and the optical wiring, an electrical wiring, an optical wiring, and the optical wiring In the photoelectric composite wiring module having a second substrate provided with a second lens for optical connection between the optical element and the optical element, provided behind either or both of the first lens and the second lens It has a structure in which lenses are pressed and fixed by an elastic body.

  According to the present invention, an angle shift between two lenses can be prevented with a simple structure.

  In addition, electrical connection and optical coupling can be performed simultaneously with a simple mounting equivalent to a conventional electronic circuit using only electrical wiring, and high optical coupling efficiency can be ensured. As a result, it is possible to provide a highly reliable and low-cost photoelectric composite wiring module and a transmission apparatus using the same.

  Further structures and effects of the present invention will be apparent from the entire description of the present application based on the description of the embodiments below.

It is sectional drawing which shows 1st embodiment by this invention. It is sectional drawing which shows 1st embodiment by this invention. It is a top view which shows 1st embodiment by this invention. It is a top view which shows 1st embodiment by this invention. It is a schematic diagram which shows the optical axis direction shift | offset | difference between the lenses by two lenses. It is a figure which shows the fluctuation | variation of the optical coupling efficiency at the time of the shift | offset | difference in Fig.3 (a). It is a schematic diagram which shows the vertical direction shift | offset | difference between the lenses by two lenses. It is a figure which shows the fluctuation | variation of the optical coupling efficiency at the time of the shift | offset | difference generate | occur | produced in Fig.4 (a). It is a mimetic diagram showing angle gap between lenses by two lenses. It is a figure which shows the fluctuation | variation of the optical coupling efficiency at the time of the shift | offset | difference generate | occur | produced in Fig.5 (a). It is a schematic diagram which shows 2nd embodiment by this invention. It is a schematic diagram which shows 2nd embodiment by this invention. It is a schematic diagram which shows 2nd embodiment by this invention. It is a schematic diagram which shows 3rd embodiment by this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  First, FIG. 1 and FIG. 2 show a first embodiment of the present invention. FIG. 1 is a cross-sectional view of a photoelectric composite wiring module according to the present invention. FIG. 1A shows an assembly process, and FIG. 1B shows a state where mounting is completed. 2 (a) and 2 (b) are top views.

  This photoelectric composite wiring module is composed of a first substrate 1 and a second substrate 2. On the first substrate 1, an optical element 11 such as a semiconductor laser or a photodiode and an optical transmission / reception circuit 12 for the optical element 11 are mounted. In this embodiment, the mounting method is flip-chip mounting using the solder bumps 13. The optical element 11 and the optical transmission / reception circuit 12 are electrically connected to each other by a solder bump and an electric wiring 14 formed on the first substrate 1. When the optical element 11 is a semiconductor laser, an electrical signal is transmitted from the optical transmission circuit 12 to the semiconductor laser via the electrical wiring 14, and converted from electricity to an optical signal by the semiconductor laser. Regarding the mounting method, both the optical element 11 and the optical transmission / reception circuit 12 may be a combination of die bonding and wire bonding other than flip-chip mounting.

  An optical signal emitted from the light emitting element / incident on the light receiving element is propagated below the first substrate. That is, the portion immediately below where the optical element 11 is mounted on the first substrate 1 is transparent to the propagating light. In this embodiment, transparency is ensured by using the first substrate as a glass material. A first lens 15 is disposed immediately below the optical element 11. This lens is shaped so that the light emitted from the light emitting element is converted into parallel light, or the parallel light incident on the light receiving element can be efficiently condensed on the aperture of the light receiving element. As a result, the light emitted from the light emitting element emits parallel light downward in the first substrate. Alternatively, parallel light incident from below the first substrate 1 enters the light receiving element. In addition, electrical wiring 16 is formed on the first substrate 1. The structure is electrically connected to the opposite side of the surface on which the optical element 11 and the optical transmission / reception circuit 12 on the first substrate 1 are mounted by a through hole or the like.

  FIG. 2A and FIG. 2B are top views of the first substrate. A light emitting element array 111, a light receiving element array 112, an optical transmission circuit 121, and an optical reception circuit 122 are mounted on the first substrate 1. The optical element and the optical transmission / reception circuit are electrically connected to appropriate portions by wiring 14 on the substrate.

  In this embodiment, the light emitting element array and the light receiving element array are in the form of an optical transceiver mounted on the same substrate. However, only the light emitting element or only the light receiving element may be used. In the present embodiment, two array elements are provided, but one or three or more array elements may be provided. Further, in this embodiment, one optical transmission / reception circuit is configured for one optical element array, but other configurations, for example, a combination of two or more optical element arrays in one optical cleaning reception circuit may be used. I do not care.

  Next, the second substrate 2 will be described with reference to FIGS. 1 (a), 1 (b), 2 (a), and 2 (b). An optical fiber 22 having a second lens 21 at the tip is disposed on the second substrate 2. The optical fiber 22 is disposed in the back surface direction of the second substrate through the through hole 23 provided in the second substrate. The optical fiber 22 and the second substrate 2 are connected by an elastic body 24 represented by a spring. An electric socket 25 is also installed on the second substrate 2.

  For example, a spring, rubber, sponge or the like can be used as the elastic body.

  The electrode 17 on the lower surface of the first substrate 1 and the terminal 26 of the electric socket 25 installed on the second substrate 2 have the same electrode arrangement, and the first substrate 1 is placed on the electric socket. It has a structure that can be connected electrically by installing.

  On the other hand, with respect to the optical coupling portion, the first lens 15 provided on the first substrate 1 and the second lens 21 provided on the second substrate 2 are in contact with each other when mounted on the electrical socket 25. It has a structure to do. At this time, the surface 19 of the first lens and the surface 29 of the second lens are formed substantially perpendicular (85 to 95 degrees) with respect to the optical axis of the lens. These two surfaces come into contact when the first substrate is attached to the electrical socket. At this time, since the elastic body exists behind the second lens, the two lenses in contact with the two surfaces are pressed by the restoring force of the elastic body 24.

  At this time, it is desirable to dispose elastic bodies on both sides of the back surface of the lens, since it is impossible to wipe off the possibility that an angle shift occurs due to one side of the back surface of one lens. More desirably, it is a ring-shaped elastic body such as a rubber ring.

  The electrical socket 25 of the second board of the first board is aligned with a fitting pin 27 or the like. The alignment accuracy is about 30 μm. The first lens and the second lens have a structure in which an optical signal emitted from the optical element is converted into parallel light by the first lens and condensed on the core of the optical fiber by the second lens. Alternatively, the optical signal emitted from the optical fiber is converted into parallel light by the second lens and is condensed on the light receiving element by the first lens. That is, the optical coupling system in this structure is a two-lens system.

  3A, FIG. 4A, and FIG. 5A are schematic diagrams showing the occurrence of positional deviation between the lenses in the two-lens system, and the fluctuation of the optical coupling efficiency at that time in FIG. b), FIG. 4B, and FIG.

  3A is briefly described as an example. In the configuration, 201 is a light source, 202 is a first lens, 400 is light, 301 is an optical fiber, 302 is a second lens, and 500 is a second member. is there.

  FIG. 3A shows the case where the optical axis is shifted in parallel, FIG. 4A shows the case where the optical axis is shifted vertically, and FIG. 5C shows the case where the angular deviation occurs. Regarding the shift parallel to the optical axis, the optical coupling efficiency hardly fluctuates as shown in FIG. As shown in FIG. 4B, the amount of positional deviation that decreases by 1 dB with respect to the vertical deviation is approximately ± 30 μm, which is relatively large.

On the other hand, as shown in FIG. 5B, regarding the angle deviation, in the present invention, which is lowered by 1 dB with a change of ± 1 degree, the alignment pins of the two lenses are used as described above. With the fitting pin structure, high-precision alignment cannot be performed, but high optical coupling efficiency can be ensured by the optical characteristics of the two-lens system. With respect to the direction parallel to the optical axis, the surface of each lens is abutted, and the structure is less likely to cause a positional shift.

  With regard to the angle deviation between the lenses, the surfaces perpendicular to the lens optical axis are abutted and pressed by the restoring force of the elastic body, so there is very little risk of positional displacement. This is a novel invention proposed by the present inventors.

  As for the optical fiber 22, an array-like ribbon fiber is used in the present embodiment, but it may be bundled or separated one by one. Furthermore, a film in which an optical waveguide is formed may be used.

  The cap 31 may be attached as necessary to avoid moisture and dust. As a device sealing method, a method such as molding other than the cap as in the present embodiment may be used.

  As described above, it is possible to provide an opto-electric composite wiring module capable of simultaneously performing high-efficiency optical coupling at the time of mounting by simple mounting equivalent to an electronic device with only electrical connection.

  Next, a second embodiment of the present invention will be described with reference to FIGS. 6 (a), 6 (b), and 6 (c).

  These drawings are sectional views showing variations of the installation structure of the optical fiber 22. FIG. 6A shows a structure in which a plate spring structure is used for the elastic body 24 instead of the coil-type spring as shown in FIG. Even in such a structure, when the lenses are pressed against each other, a restoring force is exerted, and the positional variation between the lenses is less likely to occur. Further, it is possible to obtain the same effect by disposing a resin having a small elastic modulus represented by rubber, for example, as the elastic body.

  Next, FIG. 6B shows a structure in which the optical fiber 22 is routed to the upper surface instead of the lower surface of the second substrate 2. For this reason, the second substrate is provided with a groove 231 on the upper surface instead of the through hole 23, and the optical fiber 22 is drawn from the groove 231. This groove may be provided on the lower surface of the electrical socket 25 instead of the second substrate 2. An appropriate structure may be selected according to the space on the upper and lower surfaces of the second substrate, the placement of other mounted components, and the like.

  Next, FIG. 6C is a structural example in the case where the lens 15 provided on the first substrate is made of a member different from the first substrate. A through hole 151 is provided immediately below the optical element 11 mounting portion of the first substrate 1 so that light can pass therethrough. The lens 15 is provided immediately below the hole.

  Next, as a third embodiment of the present invention, an embodiment in which the optoelectric interconnection module according to the present invention is applied to a transmission device will be described with reference to FIG.

  In FIG. 7, an IC 101 such as a switch LSI is mounted on the second substrate 2. The IC 101 is electrically connected to the optical transmission / reception circuit 12 via the electric wiring 28 on the second substrate, the electrode 26 of the electric socket, the wiring 16 of the first substrate 1 and the like. That is, an electrical signal from the IC 101 is transmitted to the optical transmission circuit 12, and further, an electrical signal is transmitted from the optical transmission circuit 12 to the light emitting element 11, and after being converted into an optical signal, the optical signal is transmitted through the optical fiber 22. Is done. Alternatively, the optical signal propagated through the optical fiber 22 is converted into an electric signal by the light receiving element 11 and reaches the IC 101 through the optical receiving circuit 12. An optical connector 102 is provided at the end of the optical fiber, and by connecting another optical fiber or the like to this end, optical transmission between boards or racks becomes possible.

  In this embodiment, the configuration of the first embodiment shown in FIG. 1 is applied as the photoelectric composite wiring module. However, the configuration of the second embodiment is also applicable.

DESCRIPTION OF SYMBOLS 1 ...... 1st board | substrate 11 ... Optical element 111 ... Light emitting element 112 ... Light receiving element 12 ... Optical transmission / reception circuit 121 ... Optical transmission circuit 122 ... Optical receiving circuit 13, 131, 132 ..Solder bump 14 ... Electric wiring 15 on first substrate 15 ... Lens 151 provided on first substrate ... Through hole 16 provided on first substrate ... Installed in first substrate Electrical wiring 17 ... Electrode pad 18 provided on the first substrate ... Fitting pin hole 19 ... Plane 2 perpendicular to the optical axis of the first lens 2 ... Second substrate 21 ... Lens 22... Optical fiber 23... Through hole 231 provided in second substrate... Groove 24... Elastic body 25. ... Electric wiring 29 on the second substrate ... perpendicular to the optical axis of the first lens Surface 31 ... cap 100 ... light electrical interconnect module 101 ... IC
102 .. Optical connector

Claims (5)

  A lens connection structure comprising a first lens and a second lens, and comprising elastic bodies on both sides of the back surface of at least one of the first lens and the second lens.   An optical apparatus using the lens connection structure according to claim 1. A first substrate comprising an optical element, an IC for driving the optical element, and a first lens for optically connecting the optical element and the optical wiring;
In the photoelectric composite wiring module having a second substrate provided with an electrical wiring, an optical wiring, and a second lens for optical connection between the optical wiring and the optical element,
A photoelectric composite wiring module having a structure in which lenses are pressed and fixed by an elastic body provided at the rear of either or both of the first lens and the second lens. A first substrate having an optical element, an IC for driving the optical element, and a first lens for optical connection between the optical element and the optical wiring;
An optical wiring, an optical wiring, and a second substrate having a second lens for optical connection between the optical wiring and the optical element; and an optical connection between the optical element and the optical wiring; In the photoelectric composite wiring module that performs electrical connection between the IC and the electrical wiring simultaneously using a connector,
A structure in which optical joining and electrical joining are performed simultaneously by bringing a plane perpendicular to the optical axis of the first lens into contact with a plane perpendicular to the optical axis of the second lens,
An optoelectric composite wiring module having a structure in which the flat surface is pressed by an elastic body provided at the back of one or both of the first lens and the second lens. 5. A transmission apparatus using the photoelectric composite wiring module according to claim 3 or 4.

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