Flexible board, optical transmission/reception module and optical transmission/reception device

The present invention relates to a flexible substrate, and an optical transmission / reception module and an optical transmission / reception device provided with the flexible substrate. Specifically, tapered portions that are oriented in the vicinity of the connection portion of the signal wiring via of the microstrip line and the vicinity of the portion corresponding to the position of the ground connection terminal of the ground conductor portion corresponding to the microstrip line are provided. This makes it possible to improve the transmission characteristics of high-frequency signals in the vicinity of the connection portion with the connector.

When electrically connecting a flexible substrate having flexibility to another substrate or the like, a method of connecting via a connector for connecting the flexible substrate is used. Further, when transmitting a high frequency signal on a printed circuit board, a printed circuit board having a microstrip line structure is used.

14 to 17 are explanatory views showing the structure of the conventional flexible substrate 50 electrically connected to the connector. FIG. 14 is a plan view showing an outline of the flexible substrate 50, and is shown by a broken line in a state where a part of the configuration is seen through for explanation. FIG. 15 is a schematic view showing the MM cross section of FIG. FIG. 16 is a plan view showing the first wiring layer 3 of the flexible substrate 50, which will be described later, and shows a state seen from above of FIG. FIG. 17 is a plan view showing the second wiring layer 5 of the flexible substrate 50, which will be described later, and shows a state seen from below of FIG. Further, FIG. 18 is a cross-sectional view showing a state in which the flexible substrate 50 is connected to the FPC (Flexible Printed Circuit) connector 7 provided on the substrate 18. The flexible substrate 50 of FIG. 18 shows the MM cross section of FIG. A part of the configuration of the substrate 18 is shown.

As shown in FIGS. 14 to 17, the flexible substrate 50 is formed by alternately stacking the first to third insulating layers and the first and second wiring layers on the upper and lower sides. The first insulating layer 2 and the third insulating layer 6 are formed of a coverlay, for example, as a protective film. In a predetermined area at the edge of the substrate, the third insulating layer 6 is not formed in order to make an electrical connection with the FPC connector 7. A reinforcing plate 53 is provided on the upper surface of the first insulating layer 2 to prevent damage when the FPC connector 7 is connected.

As shown in FIGS. 14 and 16, a solid ground layer 12b is formed on the first wiring layer 3. As shown in FIGS. 14 and 17, a signal line 9 described later is connected as each connection pad for making an electrical connection with the FPC connector 7 in the vicinity of the substrate end portion of the second wiring layer 5. A signal connection pad 52 for connecting the ground layer and a ground connection pad 51 for connecting the ground layer are provided. Each ground connection pad 51 is connected to the ground layer 12b formed in the first wiring layer 3 by a ground via 54 which is a penetrating via formed through the flexible substrate 50. Further, a pair of signal lines 9c and 9d, which are microstrip lines, are wired in the second wiring layer 5, and are connected to the signal connection pads 52, respectively.

Further, as shown in FIG. 18, the FPC connector 7 is mounted and connected on a substrate 18 configured to include a signal wiring layer 18a, an insulating layer 18b, and a ground layer 18c. The FPC connector 7 is formed by including an FPC contact portion 35a that contacts each connection pad of the flexible substrate 50, a support portion 35c that supports the housing 36, and a lead portion 35b that is connected to the substrate 18 in a resin housing 36. The metal contacts 35 to be formed are arranged in parallel in a predetermined quantity at a predetermined interval. The spacing of each connection pad on the flexible substrate 50 corresponds to the spacing of each contact 35.

Each contact 35 of the FPC connector 7 is connected by solder to a connection pad (not shown) formed on the signal wiring layer 18a of the outermost layer of the substrate 18 at a portion indicated by P of the lead portion 35b. Each connection pad of the substrate 18 is connected to a signal line, a ground pattern, or the like (not shown) formed on the signal wiring layer 18a of the substrate 18, respectively.

The FPC connector 7 shown in FIG. 18 is a type of FPC connector called a lower contact type, and as shown by O, the flexible substrate 50 is connected to the FPC connector 7 with each connection pad located on the lower surface.

With such a configuration, a high-frequency signal current is transmitted through the signal line 9 of the flexible substrate 50, the contact 35 corresponding to the signal line 9 of the FPC connector 7, and the signal line formed on the substrate 18. At this time, the feedback current for the signal current is applied to the ground layer 12b of the flexible substrate 50, the ground via 15, the contact 35 corresponding to the ground line of the FPC connector 7, and the ground layer 18c of the substrate 18 in the direction opposite to the signal current. It flows. FIG. 19 is a plan view showing the flow of the signal current and the feedback current, showing the ground layer 12b provided on the first wiring layer 3 and the signal line 9 provided on the second wiring layer 5 of the flexible substrate 50. There is. In the flexible substrate 50, as shown by the arrow Q in FIG. 19, when the signal current flows through the signal line 9, the feedback current flows through the ground layer 12b of the first wiring layer 3 as shown by the arrow R.

In addition to the above, a flexible substrate connection connector that enables insertion of a flexible substrate with a low insertion force has been proposed (see, for example, Patent Document 1).

The flexible substrate connection connector disclosed in Patent Document 1 includes a substrate insertion portion into which a flexible substrate is inserted, and also includes a cover insertion portion into which a slide cover is freely inserted and retracted on the opposite side of the substrate insertion portion. Further, the flexible substrate connection connector disclosed in Patent Document 1 includes a contact for pressing and releasing the pressure on the flexible substrate inserted into the substrate insertion portion by inserting and removing the slide cover. By providing such a configuration, the flexible substrate can be inserted with a low insertion force without interfering with the operation of the slide cover.

<patcit num="1"><text>Japanese Patent Application Laid-Open No. 2002-50423</text></patcit>

<p> However, the conventional flexible substrate 50 electrically connected to the connector described with reference to FIGS. 14 to 19 has the following problems. As shown in FIG. 18, when the flexible substrate 50 is connected to the FPC connector 7, the second wiring layer 5 provided with the signal line 9 is located on the substrate 18 side. As a result, the signal line 9 provided in the second wiring layer 5 and the ground layer 12b of the substrate 18 shown in N are coupled to generate capacitance, and the characteristic impedance of the signal line 9 is lowered. As a result, the characteristic impedance of the signal line 9 does not reach a predetermined value, so that there is a problem that the transmission characteristic of the high frequency signal is deteriorated.</p><p> Further, the flexible substrate connector disclosed in Patent Document 1 has a configuration for inserting a flexible substrate with a low insertion force, and cannot improve the transmission characteristics of a high frequency signal.</p><p> The present invention has been made to solve such a problem, and is a flexible substrate capable of improving the transmission characteristics of a high-frequency signal in the vicinity of a connection portion with a connector, and optical transmission / reception provided with this flexible substrate. It is an object of the present invention to provide a module and an optical transmitter / receiver.</p>

<p> In order to solve the above-mentioned problems, the flexible substrate according to the present invention includes a signal wiring layer having a microstrip line in the outermost signal wiring layer, and the flexible substrate electrically connected to the connector, the flexible substrate having the microstrip line. On the other outermost layer, a signal connection terminal for connecting a microstrip line to the connector is provided, and a ground connection terminal for connecting the ground conductor portion to the connector is provided at a predetermined position with respect to the signal connection terminal. The line and the signal connection terminal are connected by a signal wiring via formed through the flexible substrate, and the microstrip line gradually widens toward the signal wiring via in the vicinity of the signal wiring via. The grounding conductor part of the grounding conductor layer corresponding to the microstrip line, which is provided with a tapered part formed so as to be It is characterized by having a tapered portion formed in accordance with the shape of the tapered portion.</p><p> In the flexible substrate according to the present invention, a high-frequency signal current flows through the microstrip line provided in the signal wiring layer of the outermost layer of the flexible board and the signal wiring via connecting the microstrip line and the signal connection terminal. At this time, a feedback current flows in the ground conductor layer corresponding to the microstrip line in the direction opposite to the signal current.</p><p> Here, the microstrip line includes a tapered portion formed in the vicinity of the signal wiring via so that the line width gradually increases toward the signal wiring via. Further, the ground conductor portion of the ground conductor layer corresponding to the microstrip line is formed from the position corresponding to the position of the ground connection terminal toward the wiring direction of the microstrip line in accordance with the shape of the tapered portion of the microstrip line. It has a tapered portion.</p><p> Therefore, the coupling between the microstrip line and the ground conductor portion can be strengthened in the vicinity of the connection portion between the microstrip line and the signal wiring via, and a sudden change in the characteristic impedance of the transmission line can be suppressed.</p><p> In order to solve the above-mentioned problems, the optical transmission / reception module according to the present invention includes an optical transmission / reception circuit board, an optical transmission module connected to the optical transmission / reception circuit board, and an optical transmission module that converts an electric signal into an optical signal and outputs the optical signal. In an optical transmission / reception module including an optical reception module that converts and outputs an electric signal, the optical transmission / reception circuit board is provided on another board via a flexible board having a microstrip line in the signal wiring layer of the outermost layer. The flexible substrate is electrically connected to the connector, and the flexible substrate is provided with a signal connection terminal for connecting the microstrip line to the connector on the other outermost layer of the signal wiring layer including the microstrip line, and a predetermined value for the signal connection terminal. A ground connection terminal for connecting the ground conductor to the connector is provided at the position of, and the microstrip line and the signal connection terminal are connected by a signal wiring via formed through the flexible substrate, and the microstrip line is connected. , The ground conductor part of the ground conductor layer corresponding to the microstrip line is provided with a tapered part formed so that the line width gradually widens toward the signal wiring via in the vicinity of the signal wiring via, and is a ground connection terminal. It is characterized in that a tapered portion formed in accordance with the shape of the tapered portion of the microstrip line is provided from a portion corresponding to the position of 1 to the wiring direction of the microstrip line.</p><p> In the flexible substrate of the optical transmission / reception module according to the present invention, a high-frequency signal current is provided in the microstrip line provided in the signal wiring layer of the outermost layer of the flexible substrate and the signal wiring via connecting the microstrip line and the signal connection terminal. Flows. At this time, a feedback current flows in the ground conductor layer corresponding to the microstrip line in the direction opposite to the signal current.</p><p> Here, the microstrip line includes a tapered portion formed in the vicinity of the signal wiring via so that the line width gradually increases toward the signal wiring via. Further, the ground conductor portion of the ground conductor layer corresponding to the microstrip line is formed from the position corresponding to the position of the ground connection terminal toward the wiring direction of the microstrip line in accordance with the shape of the tapered portion of the microstrip line. It has a tapered portion.</p><p> Therefore, the coupling between the microstrip line and the ground conductor portion can be strengthened in the vicinity of the connection portion between the microstrip line and the signal wiring via, and a sudden change in the characteristic impedance of the transmission line can be suppressed.</p><p> In order to solve the above-mentioned problems, the optical transmission / reception device according to the present invention includes an optical transmission / reception circuit board, an optical transmission module connected to the optical transmission / reception circuit board, which converts an electric signal into an optical signal and outputs the signal, and an optical signal. In an optical transmitter / receiver having an optical transceiver module provided with an optical receiver module that converts Connected to the parent board via a flexible board with lines, the flexible board is provided with a signal connection terminal on the other outermost layer of the signal wiring layer with microstrip lines to connect the microstrip lines to the connector. A ground connection terminal for connecting the ground conductor to the connector is provided at a predetermined position with respect to the signal connection terminal, and the microstrip line and the signal connection terminal are connected by a signal wiring via formed through the flexible substrate. , The microstrip line is provided with a tapered portion formed in the vicinity of the signal wiring via so that the line width gradually increases toward the signal wiring via, and the ground conductor portion of the ground conductor layer corresponding to the microstrip line. Is characterized in that a tapered portion formed in accordance with the shape of the tapered portion of the microstrip line is provided from a portion corresponding to the position of the ground connection terminal toward the wiring direction of the microstrip line.</p><p> In the flexible substrate of the optical transmitter / receiver according to the present invention, a high-frequency signal current is provided in the microstrip line provided in the signal wiring layer of the outermost layer of the flexible substrate and the signal wiring via connecting the microstrip line and the signal connection terminal. Flows. At this time, a feedback current flows in the ground conductor layer corresponding to the microstrip line in the direction opposite to the signal current.</p><p> Here, the microstrip line includes a tapered portion formed in the vicinity of the signal wiring via so that the line width gradually increases toward the signal wiring via. Further, the ground conductor portion of the ground conductor layer corresponding to the microstrip line is formed from the position corresponding to the position of the ground connection terminal toward the wiring direction of the microstrip line in accordance with the shape of the tapered portion of the microstrip line. It has a tapered portion.</p><p> Therefore, the coupling between the microstrip line and the ground conductor portion can be strengthened in the vicinity of the connection portion between the microstrip line and the signal wiring via, and a sudden change in the characteristic impedance of the transmission line can be suppressed.</p>

<p> According to the flexible substrate according to the present invention, the microstrip line includes a tapered portion formed so that the line width gradually increases toward the signal wiring via, and the grounding conductor layer corresponding to the microstrip line is grounded. The conductor portion includes a tapered portion formed in accordance with the shape of the tapered portion of the microstrip line. As a result, a sudden change in the characteristic impedance of the signal current transmission line can be suppressed. Therefore, it is possible to improve the transmission characteristics of high-frequency signals in the vicinity of the connection portion between the flexible substrate and the connector.</p><p> According to the optical transmission / reception module according to the present invention, the microstrip line of the flexible substrate is provided with a tapered portion formed so that the line width gradually increases toward the signal wiring via, and is grounded corresponding to the microstrip line. The grounding conductor portion of the conductor layer includes a tapered portion formed in accordance with the shape of the tapered portion of the microstrip line. As a result, a sudden change in the characteristic impedance of the signal current transmission line can be suppressed. Therefore, it is possible to improve the transmission characteristics of high-frequency signals in the vicinity of the connection portion between the flexible substrate and the connector, and it is possible to stably transmit and receive high-speed data.</p><p> According to the optical transmitter / receiver according to the present invention, the microstrip line of the flexible substrate is provided with a tapered portion formed so that the line width gradually increases toward the signal wiring via, and is grounded corresponding to the microstrip line. The grounding conductor portion of the conductor layer includes a tapered portion formed in accordance with the shape of the tapered portion of the microstrip line. As a result, a sudden change in the characteristic impedance of the signal current transmission line can be suppressed. Therefore, it is possible to improve the transmission characteristics of high-frequency signals in the vicinity of the connection portion between the flexible substrate and the connector, and it is possible to stably transmit and receive high-speed data.</p>

Hereinafter, embodiments of the flexible substrate, the optical transmission / reception module, and the optical transmission / reception device of the present invention will be described with reference to the drawings. First, an embodiment of the flexible substrate of the present invention will be described.

&lt;Structure Example of Flexible Substrate of the Present Embodiment&gt; FIGS. 1 to 6 are explanatory views showing the configuration of the flexible substrate 1 of the present embodiment. FIG. 1 is a plan view showing an outline of the flexible substrate 1, and is shown by a broken line in a state where a part of the configuration is seen through for explanation. FIG. 2 is a schematic view showing a cross section of AA in FIG. FIG. 3 is a plan view showing the first wiring layer 3 of the flexible substrate 1 described later, and shows a state seen from above of FIG. 4 and 5 are plan views showing the second wiring layer 5 of the flexible substrate 1 described later, and show a state seen from the lower side of FIG. FIG. 4 shows a portion corresponding to FIGS. 1 and 3, and FIG. 5 shows a state in which the left-right direction of FIG. 4 is lengthened.

Further, FIG. 6 is a cross-sectional view showing a state in which the flexible substrate 1 is connected to the FPC (Flexible Printed Circuit) connector 7 provided on the substrate 18. The flexible substrate 1 of FIG. 6 shows the AA cross section of FIG. A part of the configuration of the substrate 18 is shown.

As shown in FIGS. 1 to 5, the flexible substrate 1 is formed by alternately stacking the first to third insulating layers and the first and second wiring layers on the upper and lower sides. The first and second wiring layers are formed of, for example, a metal film such as CCL (Copper Clad Laminate). The first to third insulating layers are made of epoxy-based or polyimide-based resin. The first insulating layer 2 and the third insulating layer 6 are formed of a coverlay, for example, as a protective film. In a predetermined area at the edge of the substrate, the third insulating layer 6 is not formed in order to make an electrical connection with the FPC connector 7. A reinforcing plate 8 is provided on the upper surface of the first insulating layer 2 to prevent damage when the FPC connector 7 is connected.

As shown in FIGS. 1 and 3, signal lines 9a and 9b are formed as microstrip lines in the first wiring layer 3. Further, at the end of the second wiring layer 5, a signal connection pad 10 for electrically connecting the FPC connector 7 and each signal line 9 and a ground connection pad for connecting the FPC connector 7 and the ground layer are connected. 11 is formed. Further, as shown in FIGS. 1, 4 and 5, a ground layer 12a is formed in the second wiring layer 5. As shown in L16 of FIG. 5, the ground layer 12a is formed to have a predetermined width at a location corresponding to the signal lines 9a and 9b. The width of the ground layer 12a indicated by L16 is determined in consideration of the influence of the resonance of the ground layer 12a on the surroundings.

The signal line 9 of the first wiring layer 3 and the signal connection pad 10 of the second wiring layer 5 are connected by a signal via 13 which is a penetrating via formed through the flexible substrate 1. The signal line 9 and the signal connection pad 10 are connected by, for example, three signal vias 13 in order to reduce the potential difference between them.

Further, as shown in FIG. 3, a ground guard portion 14 is formed at a portion corresponding to the position of the ground connection pad 11 in order to prevent noise from entering from the outside and interference between each signal line. In order to form the ground guard portion 14, the ground layer 12a formed in the first wiring layer 3 and the second wiring layer 5 is connected by the ground via 15 at a portion corresponding to the ground connection pad 11. In order to reduce the potential difference between the first wiring layer 3 and the second wiring layer 5 of the ground guard portion 14, they are connected by, for example, three or more ground vias 15.

As shown in FIGS. 1 and 3, the signal lines 9a and 9b include a signal line tapered portion 16 formed in the vicinity of the signal via 13 so that the line width gradually increases toward the signal via 13. Further, as shown in FIGS. 1 and 4, the ground layer 12a of the second wiring layer 5 is formed on the signal lines 9a and 9b from the location corresponding to the ground connection pad 11 in the wiring direction of the signal lines 9a and 9b. A ground layer tapered portion 17 formed in accordance with the shape of the signal line tapered portion 16 is provided.

As shown in FIG. 6, the FPC connector 7 is mounted and connected on a substrate 18 configured to include a signal wiring layer 18a, an insulating layer 18b, and a ground layer 18c. The FPC connector 7 is formed by including an FPC contact portion 35a that contacts each connection pad of the flexible substrate 1, a support portion 35c that supports the housing 36, and a lead portion 35b that is connected to the substrate 18 in a resin housing 36. The metal contacts 35 to be formed are arranged in parallel in a predetermined quantity at a predetermined interval. The spacing between the connection pads on the flexible substrate 1 corresponds to the spacing between the contacts 35.

Each contact 35 of the FPC connector 7 is connected by solder to a connection pad (not shown) formed on the signal wiring layer 18a of the outermost layer of the substrate 18 at a portion indicated by C in the lead portion 35b. Each connection pad of the substrate 18 is connected to a signal line, a ground pattern, or the like (not shown) formed on the signal wiring layer 18a of the substrate 18, respectively.

The FPC connector 7 shown in FIG. 6 is a type of FPC connector called a lower contact type, and as shown by D, the flexible substrate 1 is connected to the FPC connector 7 with each connection pad located on the lower surface.

The flexible substrate 1 of the present embodiment shown in FIGS. 1 to 6 may be configured such that a single-ended mode signal is transmitted by one signal line 9, and a differential signal is transmitted by a pair of signal lines 9. It may be configured to be transmitted.

&lt;Operation example of the flexible substrate of the present embodiment&gt; Next, an operation example of the flexible substrate 1 of the present embodiment will be described. In the flexible substrate 1 of the present embodiment, signals are transmitted by the signal lines 9a and 9b and each signal via 13. As shown in FIG. 6, when the flexible substrate 1 of the present embodiment is connected to the lower contact type FPC connector, the FPC connector 7 is mounted on the first wiring layer 3 provided with the signal line 9. It is located on the opposite side of the substrate 18. Therefore, the signal line 9 is mainly coupled to the ground layer 12a provided on the second wiring layer 5 of the flexible substrate 1, and is not coupled to the ground layer 18c provided on the substrate 18 shown in B. Therefore, it is possible to prevent a decrease in the characteristic impedance of the signal line 9 due to the coupling between the signal line 9 and the ground layer 18c of the substrate 18 to generate a capacitance, and it is possible to prevent a decrease in the transmission characteristics of a high frequency signal. ..

FIG. 7 is a plan view showing the flow of signal current and feedback current when a high-frequency signal is transmitted on the signal line 9 of the flexible substrate 1 of the present embodiment. FIG. 7 shows the signal lines 9a and 9b provided on the first wiring layer 3 of the flexible substrate 1 and the ground layer 12a provided on the second wiring layer 5. When a high-frequency signal is transmitted to each signal line 9 of the flexible substrate 1, a current flows through the signal lines 9a and 9b as shown by arrow E in FIG. At this time, a feedback current flows through the ground layer 12a as shown by the arrow F in FIG.

Here, in the flexible substrate 1 of the present embodiment, the signal lines 9a and 9b provided in the first wiring layer 3a are formed so as to gradually widen toward the signal via 13 in the vicinity of the signal via 13. The signal line taper portion 16 is provided. Further, in the vicinity of the ground connection pad 11 of the second wiring layer 5, a ground layer tapered portion 17 formed in a direction matching the signal line tapered portion 16 of the signal line 9 is provided.

Therefore, it is possible to strengthen the coupling of the ground layer 12a of the second wiring layer 5 with the signal lines 9a / 9b in the vicinity of the connection portion between the signal lines 9a / 9b and the signal via 13, and the characteristic impedance of the transmission line is abrupt. Change is suppressed. Further, as shown by the arrow F in FIG. 6, a sudden change in the feedback current path is suppressed in the vicinity of the ground connection pad 11. This makes it possible to improve the transmission characteristics of high-frequency signals at the connection points between the flexible substrate 1 and the FPC connector 7.

FIG. 8 shows the reflection loss of the signal current on the signal line 9 (S11) at each frequency of the flexible substrate 1 of the present embodiment shown in FIGS. 1 to 6 and the conventional flexible substrate 50 shown in FIGS. 14 to 18. It is a figure which shows the measurement result of). G indicates the measurement result of the flexible substrate 1 of the present embodiment, and H indicates the measurement result of the conventional flexible substrate 50.

FIG. 9 shows the transmission loss of the signal current on the signal line 9 (S21) at each frequency of the flexible substrate 1 of the present embodiment shown in FIGS. 1 to 6 and the conventional flexible substrate 50 shown in FIGS. 14 to 18. It is a figure which shows the measurement result of). I shows the measurement result of the flexible substrate 1 of this embodiment, and J shows the measurement result of the conventional flexible substrate 50.

The dimensions of each part in each measurement result are as follows. In the flexible substrate 1 of the present embodiment, the diameters of the signal vias 13 and the ground vias 15 are 0.25 mm, and the distance between the signal vias 13 and the ground vias 15 shown by L4 and L5 in FIG. 3 is 0.725 mm. The length indicated by L7 is 0.95 mm, and the length indicated by L8 is 0.65 mm. Further, the length indicated by L1 and L2 is 0.5 mm, the length indicated by L3 is 2.0 mm, the length indicated by L17 is 0.25 mm, and the length indicated by L5 is 3.0 mm.

Further, in the flexible substrate 1 of the present embodiment, the width of the signal connection pad 10 shown in L11 of FIG. 4 is 0.95 mm, and the width of the ground connection pad 11 shown in L13 is 0.65 mm. Further, the length indicated by L9 is 0.35 mm, the length indicated by L10 is 0.1025 mm, and the length indicated by L12 is 1.35 mm. In FIG. 5, the length indicated by L14 is 1.5 mm, the length indicated by L15 is 2.0 mm, and the length indicated by L16 is 2.5 mm.

Further, in the flexible substrate 1 of the present embodiment, the second insulating layer 18b is made of a polyimide resin, the relative permittivity value is 3.2, and the tan δ value is 0.005. The thickness of the substrate is 0.05 mm, and the characteristic impedance value is controlled to 50 Ω.

In order to perform stable transmission of high-speed signals, it is necessary that the reflection loss (S11) of the transmission line is -10 dB or less and the transmission loss (S21) is -3 dB or more at the frequency of the transmission data rate. Will be done. As shown in FIGS. 8 and 9, in the flexible substrate 1 of the present embodiment, the reflection loss is -16 dB or less and the transmission loss is -0.3 dB or more at 10 GHz. Therefore, in the flexible substrate 1 of the present embodiment, high-speed serial transmission of 10 Gbps can be stably performed. From the above, it can be confirmed that the flexible substrate 1 of the present embodiment can improve the transmission characteristics of high-frequency signals in the vicinity of the connection portion with the FPC connector 7.

Next, as an embodiment of the optical transmission / reception module and the optical transmission / reception device according to the present invention, an optical transmission / reception module and a network card using the flexible substrate 1 of the present embodiment will be described.

&lt;Example of Configuration of Optical Transmission / Transmission Module and Network Card of the Present Embodiment&gt; FIGS. 10 to 13 are explanatory views showing the configuration of the optical transmission / reception module 19 and the network card 20 of the present embodiment. FIG. 10 is a plan view showing an outline of a first example of the optical transmission / reception module 19 and the network card 20 of the present embodiment, and FIG. 11 is a first view of the optical transmission / reception module 19 and the network card 20 of the present embodiment. It is sectional drawing which shows the outline of an example. FIG. 12 is a plan view showing an outline of a second example of the optical transmission / reception module 19 and the network card 20, and FIG. 13 is a cross-sectional view showing an outline of the second example of the optical transmission / reception module 19 and the network card 20. In FIGS. 11 and 13, the bezel 24 described later is not shown.

The network card 20 of the present embodiment includes an optical transmission / reception module 19, is mounted in an expansion slot of a personal computer or the like, and communicates with an external information communication device or the like through an optical cable connected to an optical cable connection connector 33 described later. It enables the transmission and reception of data. The optical transmission / reception module 19 and the network card 20 have the following configurations, for example.

As shown in FIGS. 10 to 13, the network card 20 includes an optical transmission / reception module 19 having an optical cable connection connector 33, an FPC 21 for connecting an optical transmission / reception board, a host board 23 having an optical transmission / reception circuit unit B22, and an end portion of the host board 23. It is configured with a bezel 24 that can be attached to. The optical transmission / reception module 19 is attached to the host board 23 so that the optical cable connection connector 33 projects from the bezel 24. Further, the host board 23 has a card edge portion 25, and the network card 20 can be mounted in an expansion slot of a personal computer or the like at the card edge portion 25.

The optical transmission / reception module 19 includes an optical transmission / reception module housing 26, TOSA27, ROSA28, a TOSA connection FPC30, a ROSA connection FPC29, and an optical transmission / reception board 32 having an optical transmission / reception circuit unit A31.

The TOSA 27 and ROSA 28 are arranged side by side at positions corresponding to the optical cable connection connector 33 of the optical transmission / reception module housing 26. TOSA (Transmitter Optical Sub-Assembly) 27 is an optical device for transmission equipped with a laser diode or the like, has an interface to the connector of the optical cable connected to the optical cable connection connector 33, and converts an electric signal into an optical signal. And output. TOSA27 is an example of an optical transmission module. ROSA (Receiver Optical Sub-Assembly) 28 is an optical device for reception equipped with a photodiode or the like, has an interface to an optical cable connector connected to an optical cable connection connector 33, and converts an optical signal into an electric signal. And output. ROSA28 is an example of an optical receiver module.

The TOSA 27 and ROSA 28 are connected to the optical transmission / reception board 32 by the TOSA connection FPC30 and the ROSA connection FPC29, respectively. The optical transmission / reception board 32 is composed of a rigid board, and includes an optical transmission / reception circuit unit A31 connected to TOSA27 and ROSA28 via a TOSA connection FPC30 and a ROSA connection FPC29. The optical transmission / reception circuit unit A31 is provided with, for example, a drive circuit for a laser diode of TOSA27, a post-amplifier circuit for a signal received by a photodiode of ROSA28, and the like.

The optical transmission / reception board 32 is connected to the host board 23 via the optical transmission / reception board connection FPC 21. As a result, each circuit of the optical transmission / reception circuit unit A31 is connected to each circuit of the optical transmission / reception circuit unit B22 via the optical transmission / reception board connection FPC21. The optical transmission / reception circuit unit B22 is provided with, for example, a chip for PHY (Physical layer), a chip for MAC (Media Access Control), and the like. The optical transmission / reception board 32 is an example of an optical transmission / reception circuit board, and the host board 23 is an example of a parent board. The flexible substrate 1 of the present embodiment described with reference to FIGS. 1 to 6 is applied to the FPC 21 for connecting the optical transmission / reception board.

The optical transmission / reception module 19 of the first example shown in FIGS. 10 and 11 is the TOSA connection FPC30, the ROSA connection FPC29, and the optical transmission / reception board connection FPC21 and the optical transmission / reception board 32 are K in FIGS. 10 and 11. Soldering is performed at the connection points of the respective boards shown. Therefore, each board should be manufactured separately as compared with the case where the FPC30 for TOSA connection, the FPC29 for ROSA connection, the FPC21 for connecting the optical transmission / reception board, and the optical transmission / reception board 32 are integrally formed of a flex-rigid board. Is possible. Therefore, each substrate can be manufactured at low cost. Further, since each board is manufactured separately, for example, even if the design change occurs only in the FPC21 for connecting the optical transmission / reception board, only the manufacturing process of the FPC21 for connecting the optical transmission / reception board needs to be changed, and the influence of the design change. Can be suppressed to a small range.

Further, in the optical transmission / reception module 19 of the second example shown in FIGS. 12 and 13, the TOSA connection FPC30, the ROSA connection FPC29, the optical transmission / reception board connection FPC21 and the optical transmission / reception board 32 are composed of a flex rigid board. .. This eliminates the need for soldering work during manufacturing, as compared with a configuration in which each flexible board of the TOSA connection FPC30, the ROSA connection FPC29, and the optical transmission / reception board connection FPC21 is soldered to the optical transmission / reception board 32. Therefore, the manufacturing work time can be shortened, and further, it is possible to prevent the occurrence of manufacturing defects due to adverse effects on the surrounding parts due to the soldering work defects and the heat during the soldering operations.

Further, in the optical transmission / reception module 19 and the network card 20 of the present embodiment shown in FIGS. 10 to 13, the FPC 21 for connecting the optical transmission / reception board is connected by the FPC connector 34 provided on the host board 23. This makes it possible to easily attach the FPC 21 for connecting the optical transmission / reception board to the host board 23.

Further, in the optical transmission / reception module 19 and the network card 20 of the present embodiment, the TOSA27, ROSA28, the optical transmission / reception board 32 and the host board 23 are connected by a flexible board. Thereby, the arrangement of each member can be changed within the length range of each flexible substrate. For example, the optical transmission / reception module housing to which the optical transmission / reception board 32 is attached after each member is connected by the flexible substrate. It is possible to adjust the position so that the end face of the bezel 24 is aligned with the position of the bezel 24.

Further, in the optical transmission / reception module 19 and the network card 20 of the present embodiment, a part of each module and a circuit for performing optical transmission / reception is configured as an optical transmission / reception module. This makes it possible to standardize the specifications of the optical transmission / reception module with the optical transmission / reception device such as another network card, and to use the optical transmission / reception module having the same specifications as the optical transmission / reception device such as another network card. This makes it possible to reduce design and manufacturing costs.

&lt;Operation example of the optical transmission / reception module and the network card of the present embodiment&gt; Next, an operation example of the optical transmission / reception module 19 and the network card 20 described with reference to FIGS. 10 to 13 will be described. The optical transmission / reception module 19 and the network card 20 are mounted in an expansion slot of a personal computer or the like, and data is transmitted / received to / from an external information / communication device or the like through an optical cable connected to the optical cable connection connector 33 as shown below. ..

Data is transmitted to an external information communication device or the like as follows. Information necessary for data transmission is input to the optical transmission / reception circuit unit B22 as an electric signal via the card edge unit 25 connected to an expansion slot of a personal computer or the like. The information required for data transmission input to the optical transmission / reception circuit unit B22 as an electric signal is processed by the MAC chip, PHY chip, etc., and the light on the optical transmission / reception board 32 is processed via the FPC21 for connection to the optical transmission / reception board. It is input as an electric signal to the transmission / reception circuit unit A31. After that, based on the information input to the optical transmission / reception circuit unit A31, the laser diode of TOSA27 is driven by an electric signal via the FPC30 for TOSA connection, and data is transmitted as an optical signal to an external information communication device through an optical cable. Is done.

Data is received from an external information communication device or the like as follows. Data from external information and communication equipment is input to the photodiode of ROSA28 as an optical signal through an optical cable. The optical signal input to the photodiode of ROSA28 is converted into an electric signal, and is input as an electric signal to the optical transmission / reception circuit unit A31 on the optical transmission / reception board 32 via the ROSA connection FPC29. The electric signal input to the optical transmission / reception circuit unit A31 is processed by a post-amplifier circuit or the like, and then input to the optical transmission / reception circuit unit B22 on the host board 23 via the optical transmission / reception board connection FPC21. The electric signal input to the optical transmission / reception circuit unit B22 is processed by the PHY chip, the MAC chip, and the like, and is output as the received data to the personal computer and the like via the card edge unit 25.

Further, as described above, when data is transmitted / received to / from an external information / communication device through an optical cable, TOSA connection FPC30, ROSA connection FPC29, optical transmission / reception board connection FPC21, optical transmission / reception board 32, and host board 23 High-frequency electric signals are transmitted at each signal line and the joint of each substrate. For example, when high-speed serial data transmission such as 10 Gbit / s is performed, it is necessary to support high-frequency signals exceeding 10 GHz.

In the optical transmission / reception module 19 and the network card 20 of the present embodiment, the flexible substrate 1 of the present embodiment shown in FIGS. 1 to 6 is applied to the FPC 21 for connecting the optical transmission / reception board. As a result, by transmitting and receiving high-speed data, even when a high-frequency signal is transmitted at the connection point of the signal line of the flexible board to the FPC connector, high-quality signal can be transmitted and is stable. It is possible to send and receive the data.

The present invention is applied to a flexible substrate electrically connected to a connector, and an optical transmission / reception module and an optical transmission / reception device provided with this flexible substrate.

<figref num="1">It is a top view of the flexible substrate of this embodiment.</figref><figref num="2">It is sectional drawing of the flexible substrate of this embodiment.</figref><figref num="3">It is a top view of the flexible substrate of this embodiment.</figref><figref num="4">It is a top view of the flexible substrate of this embodiment.</figref><figref num="5">It is a top view of the flexible substrate of this embodiment.</figref><figref num="6">It is sectional drawing of the connector connection state of the flexible substrate of this embodiment.</figref><figref num="7">It is a top view of the flexible substrate of this embodiment.</figref><figref num="8">It is a measurement result of reflection loss.</figref><figref num="9">This is the measurement result of transmission loss.</figref><figref num="10">It is a top view of the optical transmission / reception module and the network card of the first example.</figref><figref num="11">It is sectional drawing of the optical transmission / reception module and the network card of the 1st example.</figref><figref num="12">It is a top view of the optical transmission / reception module and the network card of the 2nd example.</figref><figref num="13">It is sectional drawing of the optical transmission / reception module and the network card of the 2nd example.</figref><figref num="14">It is a top view of the conventional flexible substrate.</figref><figref num="15">It is sectional drawing of the conventional flexible substrate.</figref><figref num="16">It is a top view of the conventional flexible substrate.</figref><figref num="17">It is a top view of the conventional flexible substrate.</figref><figref num="18">It is sectional drawing of the connector connection state of the conventional flexible board.</figref><figref num="19">It is a top view of the conventional flexible substrate.</figref>

Code description

1 Flexible board, 9a Signal line, 9b Signal line, 9c Signal line, 9d Signal line, 10 Signal connection pad, 11 Ground connection pad , 12a ... ground layer, 13 ... signal via, 15 ... ground via, 17 ... ground layer taper, 19 ... optical transmission / reception module, 21 ... optical transmission / reception board connection FPC, 23 Host board, 27 TOSA, 28 ROSA, 29 ROSA connection FPC, 30 TOSA connection FPC, 32 Optical transmission / reception board