JP2013092689A - Optical module and fpc holder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent detachment in a connection part between a flexible printed circuit (FPC) and a circuit board.SOLUTION: An optical module 1 has a circuit board 4, a TOSA 5, a first FPC 7 and an FPC holder 10. The FPC holder 10 comprises: a first arm 12 including a first part 12a extending from a side surface 11a along a principal surface 4a, a second part 12b extending from the first part 12a along an end face 4c, and a third part 12c extending from the second part 12b along a rear face 4b; a second arm 13 including a protrusion part 13b protruding toward the principal surface 4a; and a third arm 14 including a fourth part 14a extending from the side surface 11a along the principal surface 4a, a fifth part 14b extending from the fourth part 14a along the end face 4c, and a sixth part 14c extending from the fifth part 14b along the rear face 4b. The protrusion part 13b presses, to the principal surface 4a, a wiring part 7c provided between one end connected to the principal surface 4a and the other end connected to the TOSA 5.

Description

  The present invention relates to an optical module and an FPC holder.

  Conventionally, an optical module has a structure in which a circuit board and an optical sub-assembly (OSA) are connected by a flexible printed circuit (FPC). In this structure, the FPC is bent and accommodated in the space between the circuit board and the optical subassembly. In FPC, the terminal is usually connected to a pad of a circuit board by solder. A force may be applied to the solder connection portion between the FPC and the circuit board by an assembly process such as an FPC connection operation or a bent FPC. In this case, peeling may occur at the solder connection portion.

  In order to solve such a problem, Patent Document 1 below discloses a structure that prevents a soldered portion from being peeled off by mounting a lead device so as to limit bending of the FPC. Patent Document 2 below discloses a structure in which an FPC is sandwiched between a circuit board and a staple and the staple is fixed to the circuit board.

JP 2009-199083 A US Patent Application Publication No. 2005/0245118

  However, the techniques disclosed in Patent Documents 1 and 2 have the following problems. That is, in the technique disclosed in Patent Document 1, when the read device does not constitute a part of the circuit, the read device is provided on the circuit board only to hold down the FPC. In this case, it is necessary to provide a through hole for the lead device in the circuit board. In addition, the number of man-hours for the circuit board manufacturing process such as the process of soldering the through hole provided with the lead device is increased. In the technique disclosed in Patent Document 2, it is necessary to provide holes for staple posts in the circuit board.

  Therefore, the present invention has been made to solve such problems, and an optical module having a structure that prevents peeling at the connection portion between the FPC and the circuit board without reducing the component mounting space of the circuit board. And it aims at providing an FPC holder.

  In order to solve the above problems, an optical module according to the present invention includes: (a) a rigid substrate; (b) an optical subassembly; (c) a flexible printed circuit board connecting the rigid substrate and the optical subassembly; And an FPC holder that presses the flexible printed circuit board against the main surface of the rigid circuit board. The FPC holder includes a main body portion extending in the first direction, and a first arm, a second arm, and a third arm that intersect with the first direction and extend from the main body portion. The first portion extends from the main body in a second direction intersecting the first direction along the main surface, and the second portion is formed along the end surface of the rigid substrate. The third part extends from the first part in the third direction intersecting the two directions, and the third part extends from the second part in the fourth direction from the second part toward the main body along the back surface of the rigid substrate. The third arm includes a fourth portion, a fifth portion, and a sixth portion, and the fourth portion extends from the main body portion in a fifth direction that intersects the first direction along the main surface. The portion extends from the fourth portion in a sixth direction that intersects the fifth direction along the end surface, and the sixth portion Is extended from the fifth portion in the seventh direction from the fifth portion toward the main body along the back surface, the second arm is disposed between the first arm and the third arm, and the second arm is The flexible printed circuit board has a protruding portion that protrudes toward the main surface, the one end connected to the main surface of the rigid substrate, the other end connected to the optical assembly, and the one end and the other end. And a protruding portion pressing the wiring portion of the flexible printed circuit board against the main surface.

  An FPC holder according to the present invention includes a main body portion extending in a first direction, and a first arm, a second arm, and a third arm that are provided on one side surface of the main body portion and extend across the first direction. The first arm includes a first portion, a second portion, and a third portion. The first portion extends from one side surface in a second direction that intersects the first direction, and the second portion includes the first direction and the first direction. Extending from the first portion in a third direction intersecting a plane defined by the second direction, the third portion extending from the second portion in a fourth direction from the second portion toward the body portion. The third arm includes a fourth portion, a fifth portion, and a sixth portion. The fourth portion extends from one side surface in a fifth direction intersecting the first direction, and the fifth portion is in the first direction. And a sixth portion extending in a sixth direction intersecting a plane defined by the fifth direction and the sixth direction, Extends from the fifth portion in a seventh direction from the fifth portion toward the body portion, the second arm is disposed between the first arm and the third arm, and the second arm is the third portion and It has the protrusion part which protrudes toward the area | region pinched | interposed into 6th part, It is characterized by the above-mentioned.

  In the optical module and the FPC holder, the FPC holder is fixed to the rigid substrate by the first arm and the third arm. In the wiring portion, the flexible printed board is pressed against the main surface of the rigid board by the second arm. For this reason, it can suppress that a tensile load is directly added to the junction part of a flexible printed circuit board and a rigid board | substrate, without providing a hole etc. in a rigid board | substrate. As a result, it is possible to prevent peeling at the joint portion between the flexible printed board and the rigid board without reducing the component mounting space of the circuit board.

  The main body portion preferably has a pair of leg portions provided so as to contact the main surface. In this case, the contact between the main body portion of the FPC holder and the flexible printed board can be prevented by the pair of leg portions. For this reason, it can suppress that the impedance of the signal line provided in FPC changes with an FPC holder.

  The main body is preferably provided on one end, and the pair of legs are in contact with the main surface on both sides of the one end. In this case, the pair of legs can prevent contact between the main body of the FPC holder and the joint between the flexible printed circuit board and the rigid circuit board. For this reason, it can suppress that the impedance of the signal line provided in FPC changes with an FPC holder.

  Either one of the first part and the fourth part preferably has a protrusion extending toward the main surface, and the main surface is preferably provided with an opening at a position facing the protrusion. In this case, the FPC holder can be more securely fixed to the rigid board by fitting the protrusion and the opening.

  The FPC holder is made of resin, and the distance between the third portion and the sixth portion is preferably smaller than the width of the flexible printed circuit board. In this case, since the distance between the third portion and the sixth portion is smaller than the width of the flexible printed board, it is possible to prevent the FPC holder from being detached from the rigid board after the FPC holder is attached.

  The protrusion preferably has a curved surface that curves away from the main surface of the rigid substrate. In this case, the flexible printed circuit board can be bent along the curved surface, and the force applied to the flexible printed circuit board can be dispersed. For this reason, disconnection of the signal line of a flexible printed circuit board by bending a flexible printed circuit board can be controlled.

  According to the present invention, it is possible to prevent peeling at the connection portion between the FPC and the circuit board without reducing the component mounting space of the circuit board.

It is an upper perspective view which decomposes | disassembles and shows schematically the optical module which concerns on this embodiment. It is an enlarged view of the FPC holder periphery of FIG. It is a figure which shows the connection method of FPC. It is an upper perspective view which shows the structure of the FPC holder of FIG. 1 schematically. It is a downward perspective view which shows the structure of the FPC holder of FIG. 1 schematically. (A) is a front view schematically showing the structure of the FPC holder of FIG. 1, and (b) is a right side view schematically showing the structure of the FPC holder of FIG. It is a top view which shows roughly the structure of the FPC holder of FIG. It is a figure which shows schematically the FPC holder 10 attached to the circuit board 4. FIG. It is sectional drawing along the IX-IX line of FIG. It is a figure for demonstrating the positional relationship of the FPC holder of FIG. 1, and FPC. It is a figure which shows schematically the FPC holder seen from the back surface of the circuit board of FIG. It is a figure for demonstrating the positional relationship of the FPC holder of FIG. 1, and a housing. It is a figure for demonstrating the attachment process of the FPC holder of FIG. It is a figure for demonstrating the subsequent process of FIG. (A) is a partially enlarged view before FPC holder attachment, (b) is a partially enlarged view after FPC holder attachment. (A) is an upper perspective view schematically showing the structure of the FPC holder according to the modification, and (b) is a front view schematically showing the structure of the FPC holder according to the modification.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is an upper perspective view schematically showing the optical module according to the present embodiment in an exploded manner. FIG. 2 is an enlarged view showing a part of the optical module shown in FIG. The optical module 1 is a module that is attached to a host device (not shown) and used for optical communication. As shown in FIGS. 1 and 2, the optical module 1 includes an upper housing 2, a lower housing 3, a circuit board 4, and an optical transmission subassembly (hereinafter referred to as “TOSA”). 5, a receiver optical sub-assembly (hereinafter referred to as “ROSA”) 6, a first flexible printed circuit board (hereinafter referred to as “first FPC”) 7, and a second flexible printed circuit board (hereinafter referred to as “ROSA”). , “Second FPC”) 8 and a flexible printed circuit board holder (hereinafter referred to as “FPC holder”) 10. In the following description, the top, bottom, front, back, left and right of the optical module 1 mean the orientation when the upper housing 2 side is up, the lower housing 3 side is down, and the side where the TOSA 5 and ROSA 6 are arranged is the front. Shall.

  The upper housing 2 and the lower housing 3 are long casings in the front-rear direction, and the components of the optical module 1 such as the circuit board 4, the TOSA 5, the ROSA 6, the first FPC 7, the second FPC 8, and the FPC holder 10 are contained therein. It is a housing for holding. The upper housing 2 and the lower housing 3 are made of a metal such as zinc, for example. The upper housing 2 functions as a lid that covers the upper portion of the lower housing 3, and the lower housing 3 functions as a bottom surface and a side wall.

  The circuit board 4 is a rigid board and has a main surface 4a, a back surface 4b, and an end surface 4c. A plurality of circuit components 41 are mounted on the main surface 4a and the back surface 4b. The end surface 4 c is a surface facing the rear end of the TOSA 5. In the circuit board 4, predetermined processing is performed on the electrical signal transmitted from the outside of the optical module 1 by the circuit component 41, and the processed signal is transmitted to the TOSA 5. In the circuit board 4, a predetermined process is performed on the signal received from the ROSA 6 by the circuit component 41, and the processed signal is transmitted to the outside of the optical module 1 as an electric signal. The main surface 4a is provided with a plurality of connection terminals 42 for electrically connecting the first FPC 7 and a plurality of connection terminals 43 for electrically connecting the second FPC 8. Furthermore, an opening 44 may be provided in the main surface 4a. The opening 44 is a hole for positioning the FPC holder 10.

  The TOSA 5 is an optical subassembly for converting an electrical signal received from the circuit board 4 into an optical signal and transmitting the converted optical signal to the outside of the optical module 1 through an optical fiber. The TOSA 5 has a plurality of lead pins 5 a for receiving an electrical signal from the circuit board 4. The ROSA 6 is an optical subassembly for converting an optical signal received from the outside of the optical module 1 through an optical fiber into an electrical signal. The ROSA 6 has a plurality of lead pins 6 a for transmitting the converted electrical signal to the circuit board 4.

  The first FPC 7 is a flexible printed circuit board extending in a band shape, and connects the circuit board 4 and the TOSA 5 to each other. A plurality of connection terminals 7a are provided at one end of the first FPC 7, and a plurality of connection holes 7b are provided at the other end. In addition, the first FPC 7 has a wiring portion 7c provided between one end and the other end. Each of the connection terminals 7a is connected to the connection terminal 42 of the circuit board 4 by soldering. Each of the connection holes 7b is connected to the lead pin 5a of the TOSA 5 by soldering. The wiring portion 7c is a portion where signal lines are arranged, and the surface thereof is covered with a cover layer. The first FPC 7 is bent and accommodated between the end face 4 c of the circuit board 4 and the TOSA 5. The first FPC 7 needs to be shortened so as not to affect the characteristics. For this reason, the first FPC 7 is connected to the main surface 4a (A surface) of the circuit board 4 at one end, is bent upward from the main surface 4a in the wiring portion 7c, and is further curved in a U shape in the wiring portion 7c. In this way, it is folded downward so as to be connected to the TOSA 5 at the other end so-called A-plane connection turning. An electrical signal from the circuit board 4 is transmitted to the TOSA 5 via the first FPC 7.

  The second FPC 8 is a flexible printed circuit board extending in a band shape, and connects the circuit board 4 and the ROSA 6 to each other. A plurality of connection terminals 8a are provided at one end of the second FPC 8, and a plurality of connection holes 8b are provided at the other end. In addition, the second FPC 8 has a wiring portion 8c provided between one end and the other end. Each of the connection terminals 8a is connected to the connection terminal 43 of the circuit board 4 by soldering. Each of the connection holes 8b is connected to the lead pin 6a of the ROSA 6 by soldering. The wiring portion 8c is a portion where signal lines are arranged, and the surface thereof is covered with a cover layer. Further, the second FPC 8 is bent and accommodated between the end face 4 c of the circuit board 4 and the ROSA 6. Specifically, the second FPC 8 is connected to the main surface 4a of the circuit board 4 at one end, is bent below the circuit board 4 at the wiring portion 8c, and is further bent in a U shape at the wiring portion 8c. And is connected to the ROSA 6 at the other end. In this way, the second FPC 8 is arranged with a so-called A-plane connection lowering. The electrical signal converted by the ROSA 6 is transmitted to the circuit board 4 via the second FPC 8. The TOSA 5 and the ROSA 6 are accommodated side by side in the left-right direction on the front side of the lower housing 3.

  Here, an FPC connection method will be described. FIG. 3 is a diagram illustrating an FPC connection method. The FPC is covered with a cover layer up to the vicinity of the terminals provided at both ends thereof. Since the FPC is mechanically protected by the cover layer, the FPC is resistant to bending at the portion covered by the cover layer. However, when it is bent at a portion not covered with the cover layer, the wiring provided in the FPC may be broken. As shown in FIG. 3A, when the first FPC 7 is connected to the TOSA 5 and the circuit board 4 by the A-side downward connection, the bending position 7e of the first FPC 7 is limited by the board edge, and the first FPC 7 is more than the board edge. It can suppress that 1st FPC7 bends in the connecting terminal 7a side of 1FPC7. Further, a force in the direction of peeling the first FPC 7 from the circuit board 4 is not applied to the solder connection portion between the connection terminal 7 a of the first FPC 7 and the connection terminal 42 of the circuit board 4. For this reason, it is preferable to use this connection method unless there is a special reason. The second FPC 8 is connected by this method.

  However, the TOSA 5 to which the first FPC 7 is connected contains an element that generates a large amount of heat. In addition, the light emitting element may be affected by heat to cause a decrease in light emission power, a change in light emission wavelength, or the like, resulting in a change in communication quality. For this reason, it is necessary to secure a heat dissipation path, and it is conceivable that heat is radiated to the outside via the upper surface 5c of the TOSA 5 and the housing in contact with the upper surface 5c. Further, by arranging the light emitting element near the heat dissipation path, the temperature of the heat generating element can be stabilized. On the other hand, a terminal 5b for transmitting / receiving a high frequency signal is connected to the light emitting element, and it is preferable to shorten the transmission path of the high frequency signal as much as possible. For this reason, it is preferable that the first FPC 7 is connected to the circuit board 4 and the TOSA 5 by an upward connection.

  Here, when the first FPC 7 is connected to the circuit board 4 and the TOSA 5 by the upward connection, it is necessary to prevent the first FPC 7 from being bent at a portion not covered by the cover layer. Therefore, as shown in FIG. 3B, a connection terminal 42 is provided on the back surface 4b (B surface) of the circuit board 4, and the connection terminal 7a and the connection terminal 42 are solder-connected on the back surface 4b. It is conceivable that the first FPC 7 is connected to the circuit board 4 and the TOSA 5 by turning on the surface. However, since the circuit component 41 is mounted on the main surface 4a, the circuit component 41 is connected to the main surface 4a from the back surface 4b provided with the connection terminals 42 via the vias 46. The connection via the via 46 is not preferable for transmission of a high-frequency signal because it causes impedance mismatch.

  Therefore, as shown in FIG. 3C, it is most advantageous for the transmission of the high-frequency signal that the first FPC 7 is connected to the circuit board 4 and the TOSA 5 by the A-side upward connection. However, in this connection method, there is no member that restricts the bending position 7e of the first FPC 7, so that the first FPC 7 is not necessarily bent at the portion (wiring portion 7c) covered with the cover layer. In addition, since the first FPC 7 is bent in the direction in which the first FPC 7 is peeled off from the main surface 4a, a force in the direction in which the first FPC 7 is peeled off from the main surface 4a of the circuit board 4 may be applied. There is a risk of adversely affecting the reliability of the solder connection part. Therefore, the bending position 7e of the first FPC 7 is limited to the wiring portion 7c by the FPC holder 10 described later, and the adverse effect on the reliability of the solder connection portion between the connection terminal 7a and the connection terminal 42 is prevented.

  The FPC holder 10 is an insulating member for pressing the first FPC 7 against the main surface 4a of the circuit board 4, and is made of a resin such as PPS (polyphenylene sulfide) or POM (polyoxymethylene). . Here, the FPC holder 10 will be described in detail with reference to FIGS. FIG. 4 is an upper perspective view schematically showing the structure of the FPC holder 10. FIG. 5 is a lower perspective view schematically showing the structure of the FPC holder 10. FIG. 6A is a front view schematically showing the structure of the FPC holder 10, and FIG. 6B is a right side view schematically showing the structure of the FPC holder 10. FIG. 7 is a plan view schematically showing the structure of the FPC holder 10. As shown in FIGS. 4 to 7, the FPC holder 10 includes a main body 11, a first arm 12, a second arm 13, and a third arm 14.

The main body 11 is a long portion extending in the first direction A1, and has a columnar shape having a side surface 11a (one side surface) and a lower surface 11b. The first arm 12 is provided on the side surface 11a of the main body 11 and extends so as to intersect the first direction A1. The first arm 12 includes a first portion 12a, a second portion 12b, and a third portion 12c, and has a shape that is folded back into a substantially U shape. The first portion 12a is in the second direction A2 crossing the first direction A1, a columnar portion extending from a side 11a, a length _{L 1} is, for example, about 5.3 mm. The first portion 12a has a first lower surface 12r. The second portion 12b is a columnar portion extending from the first portion 12a in a third direction A3 intersecting a plane defined by the first direction A1 and the second direction A2. The second portion 12b extends below the lower surface 11b. The second portion 12b has a first inner side surface 12s facing the side surface 11a. The third portion 12c is a columnar portion extending from the second portion 12b in the fourth direction A4 from the second portion 12b toward the main body 11, and has a length of about 2.5 mm, for example. The third portion 12c has a first upper surface 12t that faces the first lower surface 12r. As described above, the first arm 12 is configured so that the end of the circuit board 4 is formed by the first lower surface 12r of the first portion 12a, the first inner surface 12s of the second portion 12b, and the first upper surface 12t of the third portion 12c. Configured to hold.

The third arm 14 is provided on the side surface 11a of the main body 11 and extends across the first direction A1. The third arm 14 includes a fourth portion 14a, a fifth portion 14b, and a sixth portion 14c, and has a shape that is folded back into a substantially U shape. The fourth portion 14a is in the fifth direction A5 crossing the first direction A1, a columnar portion extending from a side 11a, a length _{L 3} is about 5.3 mm. The fourth portion 14a has a third lower surface 14r. The fifth portion 14b is a columnar portion extending from the fourth portion 14a in a sixth direction A6 intersecting a plane defined by the first direction A1 and the fifth direction A5. The fifth portion 14b extends below the lower surface 11b. The fifth portion 14b has a third inner side surface 14s facing the side surface 11a. The sixth portion 14c is a columnar portion extending from the fifth portion 14b in the seventh direction A7 from the fifth portion 14b toward the main body 11, and has a length of about 2.5 mm, for example. The sixth portion 14c has a third upper surface 14t that faces the third lower surface 14r. As described above, the third arm 14 is configured so that the end portion of the circuit board 4 is formed by the third lower surface 14r of the fourth portion 14a, the third inner surface 14s of the fifth portion 14b, and the third upper surface 14t of the sixth portion 14c. Configured to hold. Further, the distance W _ARM between the first portion 12a of the first arm 12 and the fourth portion 14a of the third arm 14 is at least larger than the width W _{FPC of the first FPC 7} .

The second arm 13 is provided on the side surface 11a of the main body 11 and extends so as to intersect the first direction A1. The second arm 13 is disposed between the first arm 12 and the third arm 14. The second arm 13 includes a seventh portion 13a and a protruding portion 13b. Seventh portion 13a is in the eighth direction A8 crossing the first direction A1, a columnar portion extending from a side 11a, a length _{L 2} is about 3.35 mm. The protruding portion 13b is a portion that protrudes in a ninth direction A9 that intersects a plane defined by the first direction A1 and the eighth direction A8. The protruding portion 13b extends below the lower surface 11b and protrudes toward a region sandwiched between the third portion 12c and the sixth portion 14c. The protruding portion 13b has a second lower surface 13r, and is gradually curved in a direction opposite to the ninth direction A9 as it proceeds from the second lower surface 13r to the eighth direction A8 (for example, a curved surface having a curvature of R1.0 mm). ). The width of the second lower surface 13r is preferably at least half of the width of the first FPC 7, for example, when the width of the first FPC 7 is 3.6 mm, it is about 2.5 mm. The length of the second lower surface 13r is, for example, about 1.6 mm in order to ensure a bending radius of 1 mm or more. Thus, the second arm 13 is configured to press the first FPC 7 against the main surface 4a of the circuit board 4 by the second lower surface 13r of the protruding portion 13b.

  Two or more of the second direction A2, the fifth direction A5, and the eighth direction A8 may be the same direction. The fourth direction A4 and the seventh direction A7 may be the same direction. Furthermore, the second direction A2 and the fourth direction A4 may be opposite directions, and the fifth direction A5 and the seventh direction A7 may be opposite directions. In the present embodiment, the second direction A2, the fifth direction A5, and the eighth direction A8 are substantially the same direction. The fourth direction A4 and the seventh direction A7 are substantially the same direction. The second direction A2 and the fourth direction A4 are opposite directions, and the fifth direction A5 and the seventh direction A7 are opposite directions. Further, the second direction A2, the fifth direction A5, and the eighth direction A8 are directions substantially orthogonal to the side surface 11a. The ninth direction A9 is a direction substantially orthogonal to the plane defined by the first direction A1 and the eighth direction A8. Further, the third direction A3 and the sixth direction A6 are inclined so as to go inward as they proceed downward.

  Further, the difference between the height of the lower surface 11b of the main body 11 and the height of the first lower surface 12r of the first portion 12a, the difference between the height of the lower surface 11b and the height of the second lower surface 13r of the protruding portion 13b, and the height of the lower surface 11b. The difference from the height of the third lower surface 14r of the fourth portion 14a is substantially the same. The difference between the height of the lower surface 11b and the height of the first upper surface 12t of the third portion 12c and the difference between the height of the lower surface 11b and the height of the third upper surface 14t of the sixth portion 14c are substantially the same. Furthermore, the distance from the side surface 11a of the main body 11 to the first inner side surface 12s of the second portion 12b and the distance from the side surface 11a to the third inner side surface 14s of the fifth portion 14b are substantially the same. Further, the length L2 of the seventh portion 13a is shorter than the length L1 of the first portion 12a and the length L3 of the fourth portion 14a. Further, the length of the third portion 12c and the length of the sixth portion 14c are such lengths that do not affect the mountability, and connect the tip of the third portion 12c and the tip of the sixth portion 14c. The straight line B is a length that intersects the triangle defined by the position P1, the position P2, and the position P3. Thus, in the present embodiment, the FPC holder 10 has a substantially symmetric shape with respect to a plane orthogonal to the longitudinal direction of the main body 11 at the center in the longitudinal direction of the main body 11.

The FPC holder 10 may further include a pair of leg portions 15 and 16. The leg portions 15 and 16 are portions provided respectively at both ends in the longitudinal direction of the main body portion 11 and projecting downward from the lower surface 11 b of the main body portion 11. Interval _{W LEG} the leg portion 15 and the leg portion 16 is larger than at least a 1FPC7 width _{W FPC} of preferably about 1.4~2.0mm greater than the width _{W FPC.} The legs 15 and 16 have substantially the same length H from the lower surface 11b. This length H is shorter than the distance from the lower surface 11b to the first upper surface 12t of the third portion 12c and the distance from the lower surface 11b to the third upper surface 14t of the sixth portion 14c, and the length H of the first portion 12a from the lower surface 11b. The distance from the first lower surface 12r and the distance from the lower surface 11b to the third lower surface 14r of the fourth portion 14a are approximately the same.

  The FPC holder 10 may further include a protrusion 17. The protrusion 17 is a portion that is provided on at least one of the first lower surface 12r of the first portion 12a and the third lower surface 14r of the fourth portion 14a and protrudes downward from the first lower surface 12r or the third lower surface 14r. The protrusion 17 is used for positioning the FPC holder 10 and is configured to fit into an opening 44 provided on the main surface 4 a of the circuit board 4. A plurality of protrusions 17 may be provided. However, in the present embodiment, the protrusions 17 are provided on the third lower surface 14r due to a click feeling for confirming that the protrusions 17 are fitted into the openings 44 and space restrictions. ing.

  Next, the FPC holder 10 attached to the circuit board 4 will be described in detail. FIG. 8 is a diagram schematically showing the FPC holder 10 attached to the circuit board 4. FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. FIG. 10 is a view for explaining the positional relationship between the FPC holder 10 and the first FPC 7. FIG. 11 is a diagram schematically showing the first FPC 7 viewed from the back surface 4 b of the circuit board 4. FIG. 12 is a view for explaining the positional relationship between the FPC holder 10 and the upper housing 2.

  As shown in FIGS. 8 to 12, in a state where the FPC holder 10 is attached to the circuit board 4, the main body 11 extends substantially parallel to the end surface 4 c of the circuit board 4, and the connection terminals 42 of the circuit board 4. And the connection terminal 7 a of the first FPC 7. The first portion 12 a of the first arm 12, the seventh portion 13 a of the second arm 13, and the fourth portion 14 a of the third arm 14 extend from the side surface 11 a of the main body 11 toward the end surface 4 c of the circuit board 4. It extends along the main surface 4a. The second portion 12b of the first arm 12 and the fifth portion 14b of the third arm 14 extend along the end surface 4c in the direction from the main surface 4a to the back surface 4b. Further, the third portion 12 c of the first arm 12 and the sixth portion 14 c of the third arm 14 extend along the back surface 4 b of the circuit board 4 in the direction from the end surface 4 c toward the main body 11. And the protrusion part 13b of the 2nd arm 13 is extended toward the main surface 4a.

  More specifically, the first lower surface 12r of the first portion 12a and the third lower surface 14r of the fourth portion 14a are in contact with the main surface 4a, and the first inner side surface 12s of the second portion 12b and the fifth surfaces 14b of the fifth portion 14b. The third inner surface 14s is in contact with the end surface 4c, and the first upper surface 12t of the third portion 12c and the third upper surface 14t of the sixth portion 14c are in contact with the back surface 4b. The first inner side surface 12s of the second portion 12b and the third inner side surface 14s of the fifth portion 14b are in contact with the end surface 4c. Further, the first FPC 7 is disposed along the outer shape of the protruding portion 13b.

  The pair of leg portions 15 and 16 are in contact with the main surface 4 a of the circuit board 4 on both the left and right sides of the joint portion between the connection terminal 7 a and the connection terminal 42 of the first FPC 7. Here, the dielectric constant of the FPC holder 10 is different from the dielectric constant of air. For this reason, when the distance between the joint between the connection terminal 42 of the circuit board 4 and the connection terminal 7a of the first FPC 7 and the FPC holder 10 is small, the impedance of the signal line passing through the joint changes with respect to the design value. May adversely affect transmission characteristics. For this reason, as shown in FIG. 10, the FPC holder 10 is separated from the joint between the connection terminal 42 of the circuit board 4 and the connection terminal 7 a of the first FPC 7 by a predetermined distance. Specifically, the distance D1 between the leg portion 15 and the connection terminal 42, the distance D2 between the leg portion 16 and the connection terminal 42, and the distance D3 between the lower surface 11b of the main body portion 11 and the joint portion are signals from the FPC holder 10, respectively. The distance is such that the influence on the impedance of the line can be ignored, and is preferably 0.7 mm or more, for example, about 1.0 mm. The first portion 12a has a step on the first lower surface 12r, and the fourth portion 14a has a step on the third lower surface 14r. This step secures the distance between the first portion 12a and the joint and the distance between the fourth portion 14a and the joint.

Further, as shown in FIG. 11, the distance W _HOLD (for example, 3.05 mm) between the third portion 12 c of the first arm 12 and the sixth portion 14 c of the third arm 14 is equal to the wiring portion 7 c of the first FPC 7. The width in the left-right direction W _FPC (for example, 3.6 mm) is smaller.

  As shown in FIG. 12, the upper housing 2 has a wall portion 2 a along the outer shape of the first arm 12 of the FPC holder 10. In a state where the optical module 1 is assembled, the first outer surface 12e of the first arm 12 is in contact with the wall surface 2b of the wall portion 2a. Further, the circuit board 4 has a protruding portion 4e extending forward from the end face 4c. This protrusion 4e is provided adjacent to the mounting position of the FPC holder 10, and has a side surface 4f that intersects the end surface 4c. The third outer surface 14e of the third arm 14 is in contact with the side surface 4f.

  Next, a method for attaching the FPC holder 10 will be described. FIG. 13 and FIG. 14 are diagrams for explaining an attachment process of the FPC holder 10. First, as shown in FIG. 13A, the main surface 4a of the circuit board 4 and the one surface 7e of the first FPC 7 face each other so that the connection terminals 42 provided on the main surface 4a of the circuit board 4 are connected to each other. The connection terminals 7a of the first FPC 7 are aligned. Then, the connection terminal 42 and the connection terminal 7 a are soldered, and one end of the first FPC 7 is joined to the main surface 4 a of the circuit board 4. Next, the lead pin 5 a of the TOSA 5 is inserted into the connection hole 7 b of the first FPC 7 from the other surface 7 d of the first FPC 7. Then, the connection hole 7 b and the lead pin 5 a are soldered, and the other end portion of the first FPC 7 is joined to the rear end portion of the TOSA 5. Subsequently, the wiring portion 7 c of the first FPC 7 is bent so that the TOSA 5 is positioned below the circuit board 4. The first arm 12, the second arm 13, and the third arm 14 are on the TOSA 5 side, the main body 11 is on the circuit board 4 side, the third portion 12c and the sixth portion 14c are on the bottom, and the FPC holder 10 is on the first FPC 7. Install from above. Specifically, the FPC holder 10 is moved downward between the circuit board 4 and the TOSA 5 so as to sandwich the wiring portion 7 c between the first arm 12 and the third arm 14.

  Then, as shown in FIG. 13B, up to a position where the second lower surface 13r comes into contact with the wiring portion 7c (or a position where the pair of leg portions 15 and 16 comes into contact with the main surface 4a of the circuit board 4). The FPC holder 10 is moved downward. Next, the FPC holder 10 is moved in the direction from the TOSA 5 toward the circuit board 4. At this time, the FPC holder 10 has the first portion 12a and the third portion 12c of the first arm 12 and the fourth portion 14a and the sixth portion 14c of the third arm 14 sandwiching the end portion of the circuit board 4, respectively. To move. Then, as shown in FIG. 14A, the FPC holder is moved to a position where the first inner side surface 12s of the second portion 12b and the third inner side surface 14s of the fifth portion 14b abut against the end surface 4c of the circuit board 4. Move 10.

  Subsequently, as illustrated in FIG. 14B, the wiring portion 7 c of the first FPC 7 is bent so that the TOSA 5 is positioned above the main surface 4 a of the circuit board 4. At this time, the wiring portion 7c is bent along the outer shape of the protruding portion 13b. The FPC holder 10 is attached to the circuit board 4 as described above.

  After the FPC holder 10 is attached to the circuit board 4, components including the circuit board 4 and the TOSA 5 are accommodated in the lower housing 3. Then, the optical module 1 is assembled by covering the opening of the lower housing 3 with the upper housing 2.

  Then, the effect of the optical module 1 is demonstrated. FIG. 15A is a partially enlarged view of the optical module 1 before the FPC holder 10 is attached, and FIG. 15B is a partially enlarged view of the optical module 1 after the FPC holder 10 is attached. As shown in FIG. 15A, since the first FPC 7 is arranged in a relatively narrow space between the end face 4c of the circuit board 4 and the rear end of the TOSA 5, with the A-plane connection turned up, the FPC holder 10 When the first FPC 7 is not attached, an upward tensile load is generated at the joint portion between the one end portion of the first FPC 7 and the circuit board 4 due to the reaction force of the first FPC 7. This tensile load is concentrated on the portion where the connection terminal 7a of the first FPC 7 and the connection terminal 42 of the circuit board 4 are joined. For this reason, there exists a possibility that the junction part of the one end part of the 1st FPC7 and the circuit board 4 may peel by the tensile load. Further, since the vicinity (one end) of the connection terminal 42 of the first FPC 7 is not covered with the cover layer, the wiring of the first FPC 7 may be broken by bending the first FPC 7 in the vicinity of the connection terminal 42.

  On the other hand, as shown in FIG. 15B, when the FPC holder 10 is attached to the circuit board 4, the wiring part 7 c of the first FPC 7 is connected to the main surface 4 a of the circuit board 4 by the protruding part 13 b of the second arm 13. Pressed against. For this reason, a tensile load is applied to the first FPC 7 at a position in contact with the protruding portion 13b. Therefore, it is possible to suppress a tensile load from being directly applied to the joint portion between the first FPC 7 and the circuit board 4. As a result, it is possible to prevent peeling of the joint portion between the first FPC 7 and the circuit board 4. Further, the protruding portion 13b has a curved shape so as to gradually move away from the main surface 4a from the second lower surface 13r toward the front. For this reason, the bending load applied to the first FPC 7 can be dispersed by bending the first FPC 7 along the outer shape of the protruding portion 13b. Moreover, since the wiring part 7c is covered with the cover layer, it can suppress that the signal line of the first FPC 7 is broken by a tensile load.

  The first lower surface 12r of the first portion 12a and the third lower surface 14r of the fourth portion 14a are in contact with the main surface 4a, and the first inner surface 12s of the second portion 12b and the third inner surface 14s of the fifth portion 14b. Is in contact with the end surface 4c, and the first upper surface 12t of the third portion 12c and the third upper surface 14t of the sixth portion 14c are in contact with the back surface 4b. For this reason, the FPC holder 10 is fixed to the circuit board 4 in the vertical direction by the first arm 12 and the third arm 14. In particular, when the first upper surface 12t of the third portion 12c and the third upper surface 14t of the sixth portion 14c are in contact with the back surface 4b, it is possible to suppress the FPC holder 10 from being lifted by the reaction force of the first FPC 7. Therefore, the protruding portion 13b can firmly press the first FPC 7 against the main surface 4a, and can prevent a tensile load from being directly applied to the joint portion between the first FPC 7 and the circuit board 4.

  Since the first inner side surface 12s of the second portion 12b and the third inner side surface 14s of the fifth portion 14b are in contact with the end surface 4c, the FPC holder 10 can be prevented from moving backward. Moreover, since the 1st FPC7 is arrange | positioned so that the external shape of the protrusion part 13b may be followed, it can suppress that the FPC holder 10 moves to a front direction. In this way, the FPC holder 10 is fixed to the circuit board 4 in the front-rear direction. Further, as shown in FIG. 12, the first outer surface 12 e of the first arm 12 is in contact with the wall surface 2 b of the upper housing 2, so that the FPC holder 10 can be prevented from moving in the right direction. As shown in FIGS. 8, 11, and 12, the third outer surface 14e of the third arm 14 is in contact with the side surface 4f of the protruding portion 4e of the circuit board 4, so that the FPC holder 10 moves to the left. Can be suppressed. Thus, the FPC holder 10 is fixed in the left-right direction with respect to the circuit board 4. As described above, the FPC holder 10 is fixed to the circuit board 4. For this reason, when a force is applied in the direction in which the FPC holder 10 is lifted by the reaction force of the first FPC 7, the position of the FPC holder 10 can be prevented from shifting, and the wiring portion 7c is connected to the main surface 4a of the circuit board 4 by the protruding portion 13b. It is possible to reliably press against.

The FPC holder 10 is made of resin and has elasticity. For this reason, the first arm 12 and the third arm 14 bend when the FPC holder 10 is attached to the circuit board 4. Therefore, the FPC holder 10 can be attached to the circuit board 4 even after the circuit board 4 and the first FPC 7 are joined and the first FPC 7 and the TOSA 5 are joined. That is, the FPC holder 10 is snap-fit to the circuit board 4. As shown in FIG. 11, since the interval W _HOLD is smaller than the width W _FPC, it is possible to prevent the FPC holder 10 from being detached due to the weight of the FPC holder 10 after the FPC holder 10 is attached to the circuit board 4. The interval W _HOLD may be larger than the width W _FPC . In this case, the FPC holder 10 can be attached to the circuit board 4 even after the circuit board 4 and the first FPC 7 are joined and the first FPC 7 and the TOSA 5 are joined regardless of whether or not the FPC holder 10 has elasticity. .

  As shown in FIG. 7, the FPC holder 10 abuts against the main surface 4a of the circuit board 4 at the pair of legs 15 and 16 (position P1 and position P2), and contacts the first FPC 7 at the protrusion 13b (position P3). Abut. As described above, the first FPC 7 can be stably held by contacting at three points. The length L2 of the seventh portion 13a is shorter than the length L1 of the first portion 12a and the length L3 of the fourth portion 14a. For this reason, the workability | operativity of attachment of the FPC holder 10 is securable. Further, by making the length L2 as long as possible, the displacement per unit length can be reduced and the stress can be dispersed. As a result, creep resistance is improved and the range of selection of the resin used for the FPC holder 10 is expanded. Further, the length of the third portion 12c and the length of the sixth portion 14c are such lengths that do not affect the mountability, and connect the tip of the third portion 12c and the tip of the sixth portion 14c. The straight line B is a length that intersects the triangle defined by the position P1, the position P2, and the position P3. By doing in this way, the load in 3 points | pieces (position P1, position P2, and position P3) by the side of the main surface 4a can be received by the 3rd part 12c and the 6th part 14c in the back surface 4b side.

[Modification]
FIG. 16A is an upper perspective view schematically showing the structure of the FPC holder according to the modification, and FIG. 16B is a front view schematically showing the structure of the FPC holder according to the modification. In the FPC holder 10, the second portion 12 b and the fifth portion 14 b are inclined so as to go inward as they go downward, whereas the second portion 22 b has the extension direction of the main body portion 21 and the first direction. It extends in a direction substantially perpendicular to the surface defined by the extending direction of the portion 22a. Similarly, the 5th part 24b is extended in the direction substantially orthogonal to the surface prescribed | regulated by the extension direction of the main-body part 21, and the extension direction of the 4th part 24a.

  Thus, since the shape of the FPC holder 20 is simpler than the shape of the FPC holder 10, the FPC holder 20 is more manufacturable than the FPC holder 10. On the other hand, the cross-sectional area of the second portion 12b along the line S12-S12 in FIG. 6A and the cross section of the fifth portion 14b along the line S14-S14 in FIG. The area is the cross-sectional area of the second portion 22b along the line S22-S22 in FIG. 16B and the cross-section of the fifth portion 24b along the line S24-S24 of FIG. Since it is larger than the cross-sectional area, the FPC holder 10 is stronger than the FPC holder 20.

  The optical module and the FPC holder according to the present invention are not limited to those described in the above embodiment. For example, the shape of each part of the FPC holder 10 is merely an example, and is not limited thereto. The main body 11, the first portion 12a, the second portion 12b, the third portion 12c, the fourth portion 14a, the fifth portion 14b, and the sixth portion 14c are columnar in shape, but may be in other shapes. . The first arm 12 and the third arm 14 may have any shape that can be attached to the circuit board 4 to which the first FPC 7 is joined. The second arm 13 pushes the first FPC 7 against the main surface 4 a of the circuit board 4. Any shape that can be applied is acceptable. At least the first inner surface 12s and the third inner surface 14s are in contact with the end surface 4c, the first upper surface 12t and the third upper surface 14t are in contact with the back surface 4b, and the protrusion 13b is in contact with the wiring portion 7c. That's fine.

  As described above, according to the present embodiment, it is possible to prevent peeling at the solder connection portion between the FPC and the circuit board without reducing the component mounting space of the circuit board.

  DESCRIPTION OF SYMBOLS 1 ... Optical module, 4 ... Circuit board, 4a ... Main surface, 4b ... Back surface, 4c ... End surface, 5 ... TOSA, 7 ... 1st FPC, 7a ... Connection terminal, 7b ... Connection hole, 7c ... Wiring part 10, 20 ... FPC holder, 11, 21 ... Main body, 11a, 21a ... Side, 12, 22 ... First arm, 12a, 22a ... First part, 12b, 22b ... Second part, 12c, 22c ... Third part, 13 , 23 ... 2nd arm, 13b, 23b ... Projection, 14, 24 ... 3rd arm, 14a, 24a ... 4th part, 14b, 24b ... 5th part, 14c, 24c ... 6th part, 15, 16, 25, 26 ... Legs, 17, 27 ... Projections, 44 ... Openings, A1 ... First direction, A2 ... Second direction, A3 ... Third direction, A4 ... Fourth direction, A5 ... Fifth direction, A6 ... Sixth direction, A7 ... seventh direction.

Claims (7)

A rigid board;
An optical subassembly;
A flexible printed circuit board connecting the rigid board and the optical subassembly;
An FPC holder that presses the flexible printed circuit board against a main surface of the rigid circuit board;
An optical module comprising:
The FPC holder includes a main body portion extending in a first direction, and a first arm, a second arm, and a third arm that intersect the first direction and extend from the main body portion,
The first arm includes a first part, a second part, and a third part,
The first portion extends from the main body portion in a second direction intersecting the first direction along the main surface,
The second portion extends from the first portion in a third direction that intersects the second direction along an end surface of the rigid substrate.
The third portion extends from the second portion in a fourth direction from the second portion toward the main body along the back surface of the rigid substrate,
The third arm includes a fourth part, a fifth part, and a sixth part,
The fourth portion extends from the main body in a fifth direction that intersects the first direction along the main surface,
The fifth portion extends from the fourth portion in a sixth direction intersecting the fifth direction along the end surface;
The sixth part extends from the fifth part in a seventh direction from the fifth part toward the main body along the back surface;
The second arm is disposed between the first arm and the third arm;
The second arm has a protrusion protruding toward the main surface,
The flexible printed circuit board includes one end connected to the main surface of the rigid board, the other end connected to the optical subassembly, and a wiring provided between the one end and the other end. And
The projecting portion presses the wiring portion of the flexible printed circuit board against the main surface.   The optical module according to claim 1, wherein the main body portion has a pair of leg portions provided so as to contact the main surface. The main body is provided on the one end,
The optical module according to claim 2, wherein the pair of legs are in contact with the main surface on both sides of the one end. Either one of the first part and the fourth part has a protrusion extending toward the main surface,
The optical module according to claim 1, wherein an opening is provided in the main surface at a position facing the protrusion. The FPC holder is made of resin,
5. The optical module according to claim 1, wherein an interval between the third portion and the sixth portion is smaller than a width of the flexible printed board.   The optical module according to claim 1, wherein the protrusion has a curved surface that is curved away from the main surface. A main body extending in the first direction;
A first arm, a second arm and a third arm which are provided on one side surface of the main body and extend across the first direction;
With
The first arm includes a first part, a second part, and a third part,
The first portion extends from the one side surface in a second direction intersecting the first direction;
The second portion extends from the first portion in a third direction intersecting a plane defined by the first direction and the second direction;
The third portion extends from the second portion in a fourth direction from the second portion toward the main body,
The third arm includes a fourth part, a fifth part, and a sixth part,
The fourth portion extends from the one side surface in a fifth direction intersecting the first direction;
The fifth portion extends from the fourth portion in a sixth direction intersecting a plane defined by the first direction and the fifth direction;
The sixth portion extends from the fifth portion in a seventh direction from the fifth portion toward the main body;
The second arm is disposed between the first arm and the third arm;
The FPC holder, wherein the second arm has a protruding portion that protrudes toward a region sandwiched between the third portion and the sixth portion.