JP2005223269A - Optical module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical module for suppressing crosstalks cased between each of the leads of an optical transmission side and an optical reception side. <P>SOLUTION: The optical module includes a photoelectric conversion element 2, provided with an optical transmission and an optical reception, the lead 16 at the optical transmission side is projectingly formed to one side 9a of adjacent sides 9a, 9b orthogonal to each other of the photoelectric conversion element 2, and the lead 17 at the optical reception side is projectedly formed to the other side 9b. A notch 12 for locating the photoelectric conversion element 2 is provided to a circuit board 3. The photoelectric conversion element 2 is located to the notch 12 of the circuit board 3, in an attitude with the lead projected forming side 9a of the optical transmission side being perpendicular to a side 3a of the circuit board 3, and the lead projected forming side 9b of the optical reception side is tilted obliquely downwardly to the side 3a of the circuit board 3. A part of the photoelectric conversion element 2 is projected from the rear side of the circuit board 3, and a housing 4 containing the photoelectric conversion element 2, and the circuit board 3 is provided with a recessed part 14 for positioning the photoelectric conversion element 2, in which the projected part of the photoelectric conversion element 2 is fitted. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical module that converts electrical signals and optical signals.

  FIG. 4 shows an example of the internal configuration of the optical module simplified by a solid line. The optical module 1 is of the SFP (Small-Form-Pluggable) type, and the optical module 1 includes an optical-electric conversion element 2 and a circuit board 3 on which an electric circuit is formed. The photoelectric conversion element 2 and the electric circuit of the circuit board 3 are accommodated and arranged in the housing 4 in a state where they are electrically connected.

  In FIG. 5, an example of the internal configuration of the photoelectric conversion element 2 is schematically shown by a solid line. The photoelectric conversion element 2 includes an optical transmission unit 6, an optical reception unit 7, a filter 8, and a package case 9. The optical transmitter 6 has a configuration that converts an electrical signal applied through the lead 16 into an optical signal having a predetermined wavelength λ1, for example, and outputs the optical signal, and includes, for example, a laser diode (LD). Yes. The optical receiving unit 7 has a configuration that, when receiving an optical signal having a set wavelength λ2, converts the received optical signal into an electrical signal and outputs the electrical signal through the lead 17, and includes, for example, a photodiode (PD). ing.

  The package case 9 has a cubic shape or a rectangular parallelepiped shape, and the optical transmission unit 6 is provided on one side 9a of adjacent surfaces orthogonal to each other, and the optical reception unit 7 is provided on the other side surface 9b. . As a result, a plurality of leads 16 on the side of the optical transmitter that are electrically connected to the optical transmitter 6 project from the surface 9 a of the package case 9, and the optical receiver 7 and the surface 9 b of the package case 9 A plurality of leads 17 on the side of the optical receiver that are electrically connected are formed to protrude.

  Furthermore, the front end portion of the ferrule 10 incorporating the optical fiber is introduced into the package case 9 from the surface 9c of the package case 9 that faces the surface on which the optical transmission unit 6 is provided. The optical fiber of the ferrule 10, the light output unit of the light transmission unit 6, and the light receiving unit of the light reception unit 7 are provided with substantially the same height.

  The filter 8 has the property of transmitting the optical signal having the wavelength λ1 output from the optical transmission unit 6 and reflecting the optical signal having the wavelength λ2 received by the optical receiving unit 7, and the wavelength emitted from the optical transmission unit 6 A filter 8 is provided so that the optical signal of λ1 can be transmitted and incident on the optical fiber of the ferrule 10, and the optical signal of wavelength λ2 emitted from the optical fiber can be reflected and received by the optical receiver 7. ing.

  Such a photoelectric conversion element 2 is arranged on one end side of the circuit board 3, and the leads 16 and 17 of the photoelectric conversion element 2 are electrically connected to the electric circuit of the circuit board 3. . An electrode pad 18 for external connection of an electric circuit provided on the circuit board 3 is formed on the other end side of the circuit board 3, and an end portion of the circuit board 3 on which the electrode pad 18 is provided is The edge connector E is used to electrically connect the optical module 1 to the outside.

  In addition, the code | symbol 11 in FIG. 4 has shown the optical connector for connector-connecting the ferrule (optical fiber) 10 with an external ferrule (optical fiber).

JP-A-11-64674

  By the way, it is preferable that the lengths of the lead 16 on the optical transmitter side and the lead 17 on the optical receiver side are short. This is because the leads 16 and 17 function as antennas, and for example, electromagnetic waves caused by electrical signals that conduct through the leads 16 on the optical transmitter side are radiated, and the leads 17 on the optical receiver side transmit the electromagnetic waves. This causes a problem of crosstalk in which noise is generated in the electrical signal picked up and conducted through the lead 17. Since the problem of crosstalk increases as the lengths of the leads 16 and 17 become longer, it is preferable that the leads 16 and 17 are shorter.

  However, the SFP type optical module 1 is manufactured based on MSA (Multi-Source-Agreement), and in the MSA, the height of the edge connector E (that is, the board surface of the circuit board 3). Therefore, the optical axis of the optical fiber is set higher by a predetermined height. Due to this standard, in the configuration shown in FIG. 4, the lengths of the leads 16 and 17 are fixed, and it is difficult to shorten the leads 16 and 17.

  The object of the present invention is to electrically connect the photoelectric conversion element and the electric circuit of the circuit board even when the distance between the circuit board surface and the height position of the optical axis of the optical fiber is fixed. An object of the present invention is to provide an optical module that facilitates shortening of leads to be connected.

  In order to achieve the above object, the present invention has the following configuration as means for solving the above problems. That is, the present invention provides an optical-electrical conversion element including an optical transmission unit that converts an electrical signal into an optical signal and outputs the optical signal, and an optical reception unit that receives the optical signal and converts the optical signal into an electrical signal and outputs the electrical signal. And a circuit board on which an electric circuit is provided. The photoelectric conversion element has adjacent surfaces orthogonal to each other, and one of the surfaces orthogonal to each other has an optical transmitter and an electric circuit. A plurality of optical transmission unit side leads that are electrically conductive are projected and formed on the other surface, and a plurality of optical reception unit side leads that are electrically conductive with the optical reception unit are projected and formed. An optical module having a configuration in which a photoelectric conversion element and a circuit board are housed and arranged in a housing in a state where the leads are electrically connected to the electric circuit of the circuit board. , A notch or through-hole for installing the photoelectric conversion element is provided. In the photoelectric conversion element, the lead protrusion formation surface on the optical transmitter side is perpendicular to the circuit board surface, and the lead protrusion formation surface on the optical receiver side is perpendicular to the circuit board surface. In the position inclined obliquely downward, it is arranged in the notch or through hole for arranging the photoelectric conversion element on the circuit board, and a part of the photoelectric conversion element protrudes to the back side of the circuit board The wall portion of the housing on the protruding side of the photoelectric conversion element is provided with a concave portion for fixing the positioning of the photoelectric conversion element in which a part of the protruding photoelectric conversion element is fitted. It is a feature.

  According to the present invention, the photoelectric conversion element is disposed on the circuit board with the lead projecting formation surface on the optical receiver side inclined obliquely downward with respect to the circuit board surface. Compared with the case where the lead protrusion forming surface on the part side is perpendicular to the circuit board surface, the part where the lead on the light receiving part side protrudes can be brought closer to the circuit board. The length of the lead can be shortened. Since the electric signal flowing through the lead on the optical receiver side is much smaller and weaker than the electric signal flowing through the lead on the optical transmitter side, the SN ratio of the electric signal flowing through the lead on the optical receiver side However, in the present invention, the lead on the optical receiver side can be shortened as described above, so that the adverse effect of crosstalk received by the electrical signal flowing through the lead on the optical receiver side is reduced, and the optical receiver It is possible to suppress the deterioration of the S / N ratio due to the crosstalk of the electric signal flowing through the side lead.

  In addition, the lead-projection forming surface on the light receiving portion side of the photoelectric conversion element is provided with a front surface connecting lead and a back surface connecting lead, for example, a light receiving portion side light- Similarly, it is easy to shorten the lengths of all the leads protruding from the electrical conversion element.

  In this invention, it is difficult to shorten all the leads protruding from the lead protrusion forming surface on the optical transmission unit side like the leads on the optical reception unit side, but among the plurality of leads on the optical transmission unit side By making the lead with the shortest lead length for signal conduction through which an electrical signal for optical signal conversion flows, the radiation amount of electromagnetic waves caused by the electrical signal for optical signal conversion can be kept small. Thereby, the crosstalk between the lead on the optical transmitter side and the lead on the optical receiver side can be suppressed.

  In addition to the above-mentioned lead for signal conduction as the lead on the optical transmitter side, the lead projecting surface on the optical transmitter side projects, as well as the lead for power supply and ground connection. Leads and the like are formed to protrude. Of these multiple leads, the lead for ground connection has the least adverse effect on the outside and the negative effect from the outside, so the lead with the longest lead length among the multiple optical transmitter side leads is connected to ground. This makes it easy to prevent problems caused by the length of the leads.

  In this invention, a part of the photoelectric conversion element protrudes to the back side of the circuit board, and a concave portion for arranging the photoelectric conversion element is formed in the housing wall on the protruding side of the photoelectric conversion element. Therefore, a part of the photoelectric conversion element can be fitted into the recess for arranging the photoelectric conversion element so that the photoelectric conversion element can be positioned and fixed to the housing.

  Embodiments according to the present invention will be described below with reference to the drawings. In the description of the embodiment described below, the same components as those of the optical module shown in FIG. 4 are denoted by the same reference numerals, and redundant description of the common portions is omitted.

  1A and 1B show a state in which the photoelectric conversion element and the circuit board constituting the optical module of this embodiment are extracted and the photoelectric conversion element and the circuit board are connected to each other. Has been. 1A is a perspective view of the optical-electrical conversion element 2 and the circuit board 3 as viewed from the edge connector E side, and FIG. 1B is an optical-electrical conversion element from the optical connector side. 2 is a perspective view when the circuit board 3 is viewed.

  An edge connector E is provided at one end of the circuit board 3, and a notch 12 is provided at the other end of the circuit board 3. The photoelectric conversion element 2 is provided in the notch 12. Is arranged. That is, the notch 12 is a notch for arranging the photoelectric conversion element.

  The photoelectric conversion element 2 has adjacent lead protrusion formation surfaces 9a and 9b orthogonal to each other, and the lead protrusion formation surface 9a is a lead protrusion on the optical transmission section side where the lead 16 on the optical transmission section side is formed to protrude. The lead projecting formation surface 9b is formed as a lead projecting formation surface on the optical receiving unit side where the lead 17 on the optical receiving unit side is formed to project. Further, in the photoelectric conversion element 2, a ferrule (optical fiber) 10 is introduced into the inside from a surface 9c facing the lead protrusion forming surface 9a, and the optical axis of the optical fiber is the lead protrusion on the optical transmission unit side. It passes through the center of the formation surface 9a and is arranged perpendicular to the lead protrusion formation surface 9a.

  This embodiment is most characteristic in the posture of the arrangement of the photoelectric conversion element 2 with respect to the circuit board 3. That is, in the conventional configuration shown in FIG. 4, both the lead protrusion formation surfaces 9 a and 9 b of the photoelectric conversion element 2 are perpendicular to the substrate surface 3 a of the circuit board 3, and thus the photoelectric conversion element. 2 was arranged. FIG. 2B schematically shows a front view when the lead protrusion forming surface 9a is viewed from the edge connector E side.

  On the other hand, in this embodiment, the lead projecting formation surface 9a on the light transmitting portion side of the photoelectric conversion element 2 is perpendicular to the circuit board surface 3a, whereas the lead on the light receiving portion side. The protrusion forming surface 9b is inclined obliquely downward with respect to the circuit board surface 3a.

  In other words, in this embodiment example, the photoelectric conversion element 2 has the optical axis of the optical fiber (in this embodiment example, the lead protrusion forming surface 9a on the optical transmission section side as shown in FIG. 2B). A straight line that passes through the center O and is perpendicular to the lead protrusion forming surface 9a) is rotated from the posture shown in FIG. The posture is as shown in 2 (a). In this embodiment, the inclination angle θ of the photoelectric conversion element 2 shown in FIG. 2A with respect to the attitude of the photoelectric conversion element 2 as shown in FIG. 2B is about 30 °. .

  In this manner, the photoelectric conversion element 2 is formed in the notch 12 of the circuit board 3 in such a posture that the lead protrusion forming surface 9b on the optical receiver side of the photoelectric conversion element 2 is inclined obliquely downward with respect to the circuit board surface. By disposing, the lead protrusion forming surface 9b on the optical receiver side is closer to the circuit board surface 3a than when the lead protruding surface 9b on the optical receiver side is perpendicular to the circuit board surface 3a. It becomes easy to shorten the lead 17 on the optical receiver side.

  In this embodiment, four leads 17 are formed in a matrix from the lead protrusion formation surface 9b on the optical receiver side, and the upper two leads 17 are formed on the surface of the circuit board 3. It is joined to an electrode pad (not shown) for connecting an electric circuit with a joining material such as solder to form a lead for surface connection. Further, the lower two leads 17 are joined to an electrode pad (not shown) for electrical circuit connection formed on the back surface of the circuit board 3 by a joining material such as solder, and are used for back surface connection. Made with Reed. That is, in this embodiment example, the front surface connection lead 17 and the back surface connection lead 17 are arranged in such a manner that the circuit board 3 is sandwiched from both the front and back sides and joined to the circuit board 3. .

  In this embodiment, the two leads 17 having the shorter lead length out of the two front surface connecting leads 17 and the two back surface connecting leads 17 are differential signals (electrical signals). This is a lead for signal conduction that conducts. Thereby, the noise of a differential signal can be reduced. That is, by reducing the length of the lead 17 through which the differential signal is conducted, the area in the loop (loop area) formed by the conduction path of the differential signal can be reduced. Since the magnetic flux of the electrical signal flowing through the lead 16 on the optical transmitter side crosses the loop, noise is added to the differential signal of the lead 17 on the optical receiver side. And the area of the loop due to the differential signal conduction path can be reduced, thereby reducing the noise of the differential signal of the lead 17 on the optical receiver side caused by the electrical signal of the lead 16 on the optical transmitter side. Can do.

  In addition, an electrical signal for optical signal conversion that is supplied to the optical transmission unit 6 through the lead 16 on the optical transmission unit side and converted into an optical signal, and after being converted from an optical signal to an electrical signal by the optical reception unit 7 Among the electrical signals after the optical signal conversion passing through the lead 17 on the optical receiver side, the electrical signal after the optical signal conversion is much smaller and weaker than the electrical signal for optical signal conversion, and crosstalk. It is easy to be affected. This embodiment is configured to shorten the lead 17 on the side of the optical receiver, which is more susceptible to crosstalk, out of the lead 16 on the side of the optical transmitter and the lead 17 on the side of the optical receiver. Thus, it is possible to effectively suppress the SN ratio deterioration caused by the crosstalk of the electrical signal after the optical signal conversion passing through the lead 17 on the optical receiver side.

  In this embodiment, the lead 16 on the optical transmitter side protrudes from each of the positions A to D in FIG. 2A on the lead protruding surface 9a on the optical transmitter side of the photoelectric conversion element 2. Has been. That is, in this embodiment, the four leads 16 on the side of the optical transmitter are formed so as to protrude from positions different from each other with respect to the circuit board surface 3a. Two of the four leads 16 on the optical transmission unit side are leads through which a differential signal (that is, an electrical signal for optical signal conversion) is conducted, and the other one is a lead for ground connection. The remaining one is a power supply lead. Of these leads, in consideration of the fact that the lead involved in the crosstalk between the lead 16 on the optical transmitter side and the lead 17 on the optical receiver side is a lead for electrical signal conduction, this embodiment example Then, the two leads 17 having a shorter lead length (that is, the two leads 17 projecting from the positions C and D in FIG. 2A) are the leads for electrical signal conduction. It is made. That is, by using the lead 17 having a shorter lead length as a lead for electrical signal conduction, the radiation amount of electromagnetic waves caused by the electrical signal for optical signal conversion from the lead 17 on the optical receiver side can be suppressed. Thereby, crosstalk between the lead 16 on the optical transmitter side and the lead 17 on the optical receiver side can be suppressed.

  In addition, among the four optical receiver side leads 17, the lead that is not easily affected by the length of the lead length is a lead for ground connection. Therefore, in this embodiment, the four optical receiver units are used. Of the leads 17 on the side, the lead having the longest lead length (that is, the lead projecting from the position B in FIG. 2A) is the lead for ground connection.

  In this embodiment, the photoelectric conversion element 2 is tilted with respect to the circuit board surface 3a and disposed in the notch 12 of the circuit board 3, so that the photoelectric conversion is performed as shown in FIG. A part of the element 2 is formed to protrude on the back side of the circuit board 3. Specifically, a corner portion (ridge line portion) K composed of a lead protrusion formation surface 9 b on the light receiving portion side of the photoelectric conversion element 2 and a bottom surface 9 d is formed to protrude on the back surface side of the circuit board 3. FIG. 3 schematically shows a part of the housing 4 in which the photoelectric conversion element 2 and the circuit board 3 are accommodated. In the housing 4, a recess (recessed portion) 14 into which the corner K protruding from the photoelectric conversion element 2 is formed is formed on the casing wall portion on the protruding side of the photoelectric conversion element 2. By fitting the protruding corner portion K of the photoelectric conversion element 2 into the recess 14, the photoelectric conversion element 2 is positioned and fixed and supported by the housing 4. That is, the concave portion 14 is a concave portion for positioning and fixing the photoelectric conversion element.

  Conventionally, the photoelectric conversion element 2 may be supported on the circuit board 3 only by the leads 16 and 17, and in this case, a large force is applied to the root portions of the leads 16 and 17, There is a possibility that the root portions 16 and 17 and the surrounding portions may be damaged. On the other hand, in this embodiment, since the entire photoelectric conversion element 2 is supported by the housing 4, it is possible to avoid applying a large force to the root portions of the leads 16 and 17. As a result, damage to the root portions of the leads 16 and 17 and the peripheral portions thereof can be prevented.

  In addition, this invention is not limited to this embodiment, Various embodiments can be taken. For example, in this embodiment, the circuit board 3 is provided with the notch 12 for arranging the photoelectric conversion elements, but instead of the notch 12, the circuit board 3 penetrates from the front surface to the back surface. You may provide the through-hole for photoelectric conversion element arrangement | positioning.

  Further, in this embodiment, four leads 16 and 17 are formed on the lead protrusion forming surfaces 9a and 9b of the photoelectric conversion element 2 respectively, but from the lead protrusion forming surfaces 9a and 9b, respectively. The number of leads formed to protrude is set according to the internal configuration of the optical transmitter 6 and the optical receiver 7, and the number of leads formed to protrude from the lead protruding surfaces 9a and 9b is four. It is not limited. In addition, the number of leads 16 that are formed to protrude on the lead protrusion formation surface 9a on the optical transmission unit side and the number of leads 17 that are formed to protrude on the lead protrusion formation surface 9b on the optical reception unit side are not necessarily the same. Sometimes they are different.

  Further, in this embodiment, the inclination angle θ of the photoelectric conversion element 2 is about 30 °, but the inclination angle θ of the photoelectric conversion element 2 is not limited to 30 °, and is notched. 12 may be set as appropriate in consideration of the size of 12 and the distance between the back surface of the circuit board 3 and the housing 4.

  Further, in this embodiment, the two leads 17 on the light receiving portion side of the photoelectric conversion element 2 are formed as front surface connecting leads, and the other two leads 17 are formed as rear surface connecting leads. However, depending on various conditions such as the inclination angle of the photoelectric conversion element 2 with respect to the circuit board surface 3a and the number of leads 17 provided on the lead protrusion forming surface 9b, all of the leads 17 on the optical receiver side May be formed as leads for front surface connection, or all of the leads 17 on the optical receiver side may be formed as leads for back surface connection. The connection configuration between the lead 17 and the circuit board is as follows. It is not particularly limited.

  Further, in this embodiment example, the optical module 1 is an SFP type optical module, which is manufactured based on the MSA. However, the present invention is an optical module including an optical transmitter and an optical receiver. Any optical module having an electrical conversion element and a circuit board electrically connected to the electrical conversion element can be applied to optical modules other than the SFP type. In the present invention, a part of the photoelectric conversion element protrudes from the back side of the circuit board, and the photoelectric conversion element is a recess for arranging the photoelectric conversion element provided on the housing. And is supported by the housing. With this configuration, for example, when the distance between the optical axis of the optical fiber and the circuit board surface is changed due to a design change, the opto-electric conversion element is conventionally supported by the circuit board. The design was troublesome due to significant changes such as changing all the lead lengths of the conversion elements and also changing the support portions of the photoelectric conversion elements. In this invention, since only the rotation angle of the photoelectric conversion element is changed, the change of the lead length of the photoelectric conversion element is minimal, and the design can be changed by slightly moving the recess on the housing side. Can respond quickly.

It is a figure for demonstrating one embodiment of the optical module which concerns on this invention. It is a figure for demonstrating the example of arrangement | positioning of the photoelectric conversion element with respect to the circuit board shown in FIG. It is a model figure for demonstrating the form example of the housing | casing which comprises the optical module of the example of an embodiment. It is a model figure for demonstrating an example of the conventional optical module. It is a figure for demonstrating an example of the internal structure of a photoelectric conversion element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical module 2 Optical-electric conversion element 3 Circuit board 4 Case 6 Optical transmission part 7 Optical reception part 12 Notch 14 Recessed part for optical-electrical conversion element arrangement | positioning 16 Lead on the optical transmission part side 17 Optical reception part side Lead

Claims (3)

  An optical-electrical conversion element including an optical transmission unit that converts an electrical signal into an optical signal and outputs the optical signal, an optical reception unit that receives the optical signal and converts the optical signal into an electrical signal, and outputs the electrical signal, and an electrical circuit are provided And the photoelectric conversion element has adjacent surfaces orthogonal to each other, and a plurality of surfaces electrically orthogonal to the optical transmitter are provided on one side of the surfaces orthogonal to each other. A lead on the optical transmitter side is formed to protrude, and a plurality of leads on the side of the optical receiver that are electrically connected to the optical receiver unit are formed to protrude on the other side. An optical module having a configuration in which an optical-electrical conversion element and a circuit board are accommodated in a housing in a state of being electrically connected to an electric circuit, wherein the circuit board includes the optical-electrical conversion element There are notches or through-holes for installation, and light-electricity In the conversion element, the lead protrusion forming surface on the optical transmitter side is perpendicular to the circuit board surface, and the lead protrusion forming surface on the optical receiver side is inclined obliquely downward with respect to the circuit board surface. The optical-electrical conversion element is arranged in a notch or a through-hole for arranging the optical-electrical conversion element on the circuit board, and a part of the optical-electrical conversion element protrudes to the back side of the circuit board. An optical module, wherein a wall portion of a housing on the projecting side is provided with a concave portion for positioning the light-electrical conversion element in which a part of the projecting optical-electrical conversion element is fitted.   The lead projection forming surface on the optical receiver side of the photoelectric conversion element is provided with a lead for surface connection connected to the surface of the circuit board and a lead for back connection connected to the back surface of the circuit board. The optical module according to claim 1, wherein:   The plurality of leads on the optical transmission part side of the photoelectric conversion element are formed to protrude from positions where the heights relative to the circuit board surface are different from each other on the surface of the lead projection formation surface on the optical transmission part side, and are connected to the circuit board. The lead length to the part is different from each other, and the lead having the shortest lead length among the plurality of leads on the optical transmission part side is used for signal conduction for conducting an electrical signal for optical signal conversion, 3. The optical module according to claim 1, wherein the lead having the longest lead length is used for ground connection.

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