JP2012222212A - Optical data link - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical data link which is formed by electrically connecting an OSA having a ceramic package and a circuit board in a housing via an FPC, and can be made compact.SOLUTION: In the optical data link, a TOSA 20 where an LD is mounted in a ceramic package 21a formed by stacking rectangular ceramic frames is connected electrically with a circuit board, on which an electronic component group transmitting and receiving electric signals is mounted, via the FPC 30 in the housing. The FPC 30 is arranged along one side of the ceramic package 21a parallel with the surface of the circuit board where electrode pads are formed, and connected electrically by soldering without being folded.

Description

  The present invention relates to an optical data link for transmitting and / or receiving optical signals.

  The optical data link used for optical communication includes a transmitting optical sub-assembly (TOSA) that transmits optical signals and a receiving optical sub-assembly (ROSA) that receives optical signals. An optical sub-assembly (OSA: Optical Sub-Assembly) is mounted in a housing together with a circuit board on which a large number of electronic components are mounted. Of these optical data links, one having both transmission and reception functions is generally called an optical transceiver.

  FIG. 8 is a diagram illustrating an example of an OSA used in an optical transceiver, in which 101 indicates TOSA. The TOSA 101 includes an optical module 102 on which a laser diode (LD) is mounted and a sleeve portion 103 for connection to an optical fiber. The optical module 102 has a CAN package 102a which is a cylindrical package, and a lead terminal 102b for wiring to a circuit board (hereinafter referred to as an external circuit board) in the optical transceiver is provided at the bottom of the package 102a. Is provided.

  When used for high-speed transmission optical communication of 10 Gbit / s or more, a flexible printed circuit board (FPC) 110 is attached to a lead terminal 102b for impedance matching of a signal path, and an external circuit board is passed through the FPC 110. And OSA 101 are electrically connected (see, for example, Patent Document 1).

In recent years, development of an optical module using a ceramic package formed by laminating a rectangular ceramic frame that is smaller and less expensive than the above-mentioned CAN package has been advanced.
FIG. 9 is a diagram illustrating an example of an OSA having an optical module using a ceramic package, in which 201 indicates TOSA. As shown in the drawing, the TOSA 201 includes an optical module 202 having a ceramic package 202a (hereinafter referred to as PKG 202a) containing an LD, and a sleeve portion 203 for connection to an optical fiber. Similarly to the TOSA 101 in FIG. 8, the TOSA 201 uses an FPC for electrical connection with the circuit board.

10A and 10B are diagrams for explaining an example of a method for attaching the FPC 210 to the TOSA 201 in FIG. 9, FIG. 10A is a perspective view of the TOSA 201 with the FPC 210 attached, and FIG. 10B is a side view thereof.
As shown in FIG. 10A, the FPC 210 is soldered to the PKG 202a in a state where it is set in contact with the bottom surface 202b of the PKG 202a. At this time, the solder spreads at the interface between the PKG 202a and the FPC 210, and at the same time becomes a fillet in the castellation portion 202c (see FIG. 9) on the side of the PKG 202a.

  Further, the connection surface of the external circuit board with the FPC 210 extends in a direction perpendicular to the bottom surface 202b of the PKG 202a, and the FPC 210 can be electrically connected to the external circuit board as shown in FIG. It is bent so as to project toward the outer side of the PKG 202a (see, for example, Patent Document 2).

  The polyimide reinforcing plate 220 is attached to the side opposite to the solder connection surface of the FPC 210 so that a large stress is not applied to the solder fillet F by bending as described above. Further, the end of the reinforcing plate 220 is the bent portion 211, but it is bent at a bending radius of 0.5 mm or more because it is necessary to maintain a bending radius that does not break from the viewpoint of the flexibility of the FPC 210. The FPC 210 jumps out of the PKG 202a by the sum of the bending radius and the fillet F, that is, about 1.5 mm.

JP 2005-286305 A US Pat. No. 7,476,040

However, the jumping out of the FPC 210 described above may interfere with or come into contact with the housing of the optical transceiver in a small optical transceiver, which hinders downsizing.
The above problems are neither disclosed nor suggested in Patent Document 1.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to provide an optical data link that can be reduced in size, in which an OSA having a ceramic package and a circuit board are electrically connected via an FPC in a housing. .

  The optical data link of the present invention includes an optical module in which a photoelectric conversion element is mounted in a ceramic package formed by stacking rectangular ceramic frames, and a circuit board on which an electronic component group that transmits and receives electrical signals is mounted. Is electrically connected through a flexible printed circuit board in the casing, and the flexible printed circuit board is arranged along the side surface of one side of the ceramic package parallel to the surface on which the electrode pads of the circuit board are formed. In addition, the electrode formed on the side surface of one side is electrically connected by soldering without being bent.

  Further, the flexible printed circuit board may be arranged along the side surface of the other side of the ceramic package, and electrically connected to the electrode formed on the side surface of the other side by soldering.

  According to the present invention, the flexible printed circuit board is disposed along the side surface of one side of the ceramic package parallel to the surface on which the electrode pads of the circuit board are formed, and is electrically connected to the electrode formed on the side surface of the one side by soldering. Since the flexible printed circuit board does not come into contact with the housing because it is connected, the housing of the optical data link can be reduced in size.

1 is an external view of an optical transceiver that is an example of an optical data link according to the present invention. FIG. It is a figure of the state which removed the upper cover of FIG. It is sectional drawing for demonstrating TOSA of FIG. It is a perspective view for demonstrating TOSA of FIG. It is a figure which shows typically a mode when FPC is attached to TOSA of FIG. It is a figure which shows the specific example of FPC of FIG. It is a figure which shows the other example of FPC in connection with this invention. It is a figure which shows an example of OSA used for the conventional optical transceiver. It is a figure which shows an example of OSA which has an optical module using a ceramic package. It is a figure explaining the subject of this invention.

  Embodiments of the present invention will be described with reference to the drawings. The optical data link according to the present invention can be applied to an optical transceiver 10 having a shape as shown in FIG. 1 as an example. The optical transceiver 10 includes an upper cover 11 and a lower cover 12 that cover an OSA having a ceramic package on which a photoelectric conversion element such as an LD is mounted and a circuit board on which an electronic component group that transmits and receives electrical signals is mounted. Configured.

  The upper cover 11 and the lower cover 12 also serve as a housing of the optical transceiver 10 and have a function as a heat radiating body for heat-generating components mounted inside by being made of metal. A front portion of the upper and lower covers 11, 12 has a flange portion 13 for mounting the host device so as to close the mounting opening, and a receptacle portion 14 for mounting an optical connector is provided in front of the flange portion 13. At the rear of the upper and lower covers 11 and 12, an electrical connector portion 15a formed at the hard end of the circuit board protrudes and is used for electrical connection with the host device.

  FIG. 2 is a diagram showing a state in which the upper cover 11 of FIG. 1 is removed, and shows the inside of the optical transceiver 10. A circuit board 15 is mounted on the lower cover 12, and an electronic component group, an IC 19, and the like for photoelectric conversion and transmission / reception of electrical signals are mounted. A TOSA 20 that transmits an optical signal and a ROSA 40 that receives an optical signal are mounted on the front of the lower cover 12, and are electrically connected to the circuit board 15 via flexible circuit boards 30 and 50. In addition, the heat dissipation block 16 is thermally adhered to the TOSA 20 using the elastic member 17 so that heat from the heat generating component in the TOSA 20 is transmitted to the upper cover 11 via the heat dissipation block 16.

  3 and 4 are views for explaining the TOSA 20, FIG. 3 is a sectional view of the TOSA 20, and FIGS. 4A and 4B are perspective views thereof. As shown in FIG. 3, the TOSA 20 is connected to an optical module 21 having a ceramic package 21a (hereinafter referred to as PKG 21a) formed by laminating a plurality of rectangular ceramic frames. A sleeve 23 for forming a bond is combined. The PKG 21a of the optical module 21 forms a side wall portion 21b by laminating a plurality of rectangular ceramic frames, and uses a metal plate as a bottom wall on the back surface to form a heat radiating surface portion 24. A connecting portion 21d is provided on the upper portion of the side wall portion 21b to be fitted and connected to the joint sleeve 22 via the auxiliary wall 21c.

  An electronic cooling device (TEC: Thermo-Electric Cooler) 25 such as a Peltier element is mounted on the heat radiating surface portion 24 forming the bottom wall of the PKG 21 a, and the heat generating electrode side is joined to the heat radiating surface portion 24. On the heat absorbing electrode side of the TEC 25, an LD or the like as a heat generating component is mounted, and the operating temperature of the LD is adjusted and controlled. In addition to the LD, a photodiode for monitoring the light emission state of the LD, a condensing lens for condensing the signal light from the LD and optically coupling it to the optical fiber, and the like are mounted inside the PKG 21a.

  The joint sleeve 22 is for aligning and connecting the optical module 21 and the sleeve 23. The optical module 21 is aligned with respect to the axial direction indicated by the arrow Z in the cylindrical fitting portion of the connecting portion 21f. The sleeve 23 is performed by adjusting the joining position in the surface direction of the sleeve end by aligning in the arrow XY direction.

  The sleeve 23 is for connecting an optical fiber for sending an optical signal to the outside. The sleeve 23 has a ferrule insertion hole 23a into which a ferrule attached to the end of the optical fiber is inserted, and includes a stub 23b in which a short optical fiber 23c is accommodated. The signal light transmitted from the LD of the optical module 21 is collected at the input end of the short optical fiber 23c, and transmitted from the output end to the optical fiber inserted into the ferrule insertion hole 23a.

  As shown in FIG. 4, the heat radiating surface portion 24 that forms the bottom wall of the back surface of the PKG 21a is formed in a rectangular shape so as to slightly protrude from the back surface of the PKG 21a. Further, the side wall portion 21a of the PKG 21a is provided with a first terminal portion 21e on one side of the two sides avoiding the heat radiating surface portion 24, and a second terminal portion 21f on the other side. The first terminal portion 21e is provided on the electrode pad 21g provided on the bottom surface below the side wall portion 21a (upward in FIG. 4B) and on the side surface on the same lower side that is electrically continuous with the electrode pad 21g. The second terminal portion 21f includes an electrode pad 21j provided on the side bottom surface of the side wall portion 21a, and a side surface on the same side that is electrically continuous with the electrode pad 21j. It consists of the provided electrode, ie, the castellation part 21k. The FPC 30 (see FIG. 2) is connected to the first terminal portion 21e and the second terminal portion 21f, and is electrically connected to the circuit board 15.

FIGS. 5A and 5B are views schematically showing the FPC 30 attached to the TOSA 20, FIGS. 5A and 5B are perspective views, and FIG. 5C is a side view.
As shown in FIGS. 5A and 5B, the FPC 30 includes a first circuit terminal portion 31 connected to the first terminal portion 21e of the optical module 21 and a second circuit connected to the second terminal portion 21f. The terminal part 32, the board side circuit terminal part 33 connected to the circuit board 15 (see FIG. 2), the first circuit terminal part 31, and the wiring connecting the second circuit terminal part 32 and the board side circuit terminal part 33 Part 34.

The FPC 30 is set so that the first circuit terminal portion 31 is in contact with the first terminal portion 21e on the side surface side of the PKG 21a without being bent, and the second terminal portion 21f on the bottom surface side is in contact with the second circuit terminal portion 32. In this state, it is soldered to the PKG 21a.
At the time of this soldering, the connection surface of the circuit board 15 (see FIG. 2) with the FPC 30 and the side surface of the first terminal portion 21e of the PKG 21a connected to the first circuit terminal portion 31 of the FPC 30 are parallel. As shown in FIG. 5C, it is not necessary to bend the first circuit terminal portion 31 side. Therefore, the amount of protrusion of the FPC 30 adjacent to the lower cover 12 (see FIG. 2) with respect to the PKG 21a on the first circuit terminal portion 31 side can be suppressed to the thickness of the FPC 30, and the lower cover 12, that is, the housing of the optical transceiver 10 and the FPC 30 Therefore, the housing of the optical transceiver 10 can be reduced in size.

Further, since the FPC 30 is not bent, the length of the FPC 30 can be shortened, so that the electrical characteristics can be improved and the durability can be improved.
In addition, although the formation part of the 2nd circuit terminal part 32 of FPC30 is bent when setting for soldering with PKG21a, it is preferable to attach a bending crease to FPC30 beforehand.

FIG. 6 is a development view showing a specific example of the FPC 30.
As shown in the figure, the FPC 30 has electrode pads 31 a, 32 a, and 33 a formed on a first circuit terminal portion 31, a second circuit terminal portion 32, and a substrate side circuit terminal portion 33. Further, the FPC 30 has a wiring pattern (not shown), and the electrode pad 31a of the first circuit terminal portion 31 and the electrode pad 33a of the substrate side circuit terminal portion 33 are electrically connected by the wiring pattern. The electrode pad 32a of the two-circuit terminal portion 32 and the electrode pad 33a of the substrate-side circuit terminal portion 33 are electrically connected. Further, the flat FPC 30 has a cut 35 formed between the first circuit terminal portion 31 and the second circuit terminal portion 32. If this notch 35 is not present, the bending radius of the portion where the second circuit terminal portion 32 of the FPC 30 is formed becomes small, which is not preferable from the viewpoint of flexibility. However, the notching 35 can increase the bending radius. So there is no problem with flexibility.

FIG. 7 is a perspective view showing another example of the FPC according to the present invention, and parts similar to those in FIG. 6 are denoted by the same reference numerals, and description thereof is omitted.
In the FPC 30 ′ of FIG. 7, unlike the FPC 30 of FIG. 6, the second terminal portion 21f on the side surface side of the PKG 21a and the second circuit terminal portion 32 ′ are set to be in contact with each other and soldered to the PKG 21a. Therefore, the amount of protrusion of the FPC 30 ′ with respect to the PKG 21a on the second circuit terminal portion 32 side can be suppressed to the thickness of the FPC 30 ′, and the side portion of the housing of the optical transceiver 10 and the FPC 30 do not interfere with or come into contact with each other. The size of the optical transceiver 10 can be reduced not only in the thickness direction but also in the width direction.

DESCRIPTION OF SYMBOLS 10 ... Optical transceiver, 20 ... TOSA, 21 ... Optical module, 21a ... Ceramic package, 21e ... 1st terminal part, 21f ... 2nd circuit terminal part, 22 ... Joint sleeve, 23 ... Sleeve, 30, 50 ... FPC, 31 ... 1st circuit terminal part, 32 ... 2nd circuit terminal part, 33 ... Board side circuit terminal part, 34 ... Wiring part, 40 ... ROSA.

Claims (2)

An optical module in which photoelectric conversion elements are mounted in a ceramic package formed by stacking rectangular ceramic frames, and a circuit board on which an electronic component group for transmitting and receiving electrical signals is mounted is a flexible printed circuit board. An optical data link electrically connected via
The flexible printed circuit board is disposed along a side surface of one side of the ceramic package parallel to a surface on which the electrode pads of the circuit board are formed, and is soldered without being bent with respect to the electrode formed on the side surface of the one side. An optical data link characterized by being electrically connected by attachment.   The said flexible printed circuit board is distribute | arranged along the side surface of the other side of the said ceramic package, and is electrically connected with the electrode formed in the side surface of the said other side by soldering. Optical data link.

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