JP5928294B2 - Circuit module and optical communication device - Google Patents

Description

  The present invention relates to a circuit module and an optical communication device, and more particularly to a circuit module and an optical communication device including a flexible substrate.

  In recent years, the Internet has become widespread, and users can access various information on sites operated in various parts of the world and obtain the information. Along with this, devices capable of broadband access such as ADSL (Asymmetric Digital Subscriber Line) and FTTH (Fiber To The Home) are rapidly spreading.

  In IEEE Std 802.3ah (registered trademark) -2004 (non-patent document 1), a plurality of home side devices (ONU: Optical Network Unit) share an optical communication line, and a station side device (OLT: Optical Line Terminal). One method of a passive optical network (PON), which is a medium-sharing communication that performs data transmission with the network, is disclosed. That is, EPON (Ethernet (registered trademark) PON) in which all information is communicated in the form of an Ethernet (registered trademark) frame, including user information passing through the PON and control information for managing and operating the PON, and EPON An access control protocol (MPCP (Multi-Point Control Protocol)) and an OAM (Operations Administration and Maintenance) protocol are defined. By exchanging MPCP frames between the station side device and the home side device, the home side device joins and leaves, and uplink access multiplexing control is performed. Non-Patent Document 1 describes a registration method for a new home device, a report indicating a bandwidth allocation request, and a gate indicating a transmission instruction using an MPCP message.

  In addition, IEEE 802.3av (registered trademark) -2009 is standardized as the next generation technology of GE-PON (Giga Bit Ethernet (registered trademark) Passive Optical Network), which is an EPON realizing a communication speed of 1 gigabit / second. Even in the 10 G-EPON, that is, the EPON corresponding to a communication speed of 10 gigabits / second, the access control protocol is premised on MPCP.

  In recent years, the use of flexible printed circuits (FPC: Flexible Printed Circuits) has been expanded along with miniaturization of electric devices (see, for example, JP-A-2006-32216 (Patent Document 1)). By using a flexible substrate, it is possible to reduce wiring space and perform efficient component placement.

JP 2006-32216 A

  In various fields such as the field of optical communication as described above, downsizing of various devices is required, and it is desired to use a flexible substrate effectively.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a circuit module and an optical device capable of effectively using a flexible substrate in a configuration for transmitting and / or receiving electrical signals. It is to provide a communication device.

  A circuit module according to an aspect of the present invention includes a device for transmitting or receiving an electrical signal, a rigid board for transmitting an electrical signal to the device or transmitting an electrical signal from the device, and the above A flexible board for electrically connecting the device and the rigid board, and a connector provided on the rigid board for detachably connecting the rigid board and the flexible board.

  As described above, the connection between the flexible substrate and the rigid substrate is not performed by soldering but by the connector, so that a device having a short life and easily damaged can be detached from the rigid substrate. That is, it is possible to prevent disposal and replacement of the entire circuit module including the rigid board due to device defects, and to reduce processing costs for soldering and the like. Therefore, in the circuit module according to the present invention, the flexible substrate can be effectively used in a configuration that performs at least one of transmission and reception of electric signals.

  Preferably, the flexible substrate includes an impedance adjusting unit for adjusting an impedance of an electric signal transmission path at a connection portion with the connector.

  With such a configuration, the impedances of the electrical connection portions of the flexible substrate and the flexible substrate connector can be adjusted so as to approach the impedances of the transmission paths on the transmission side and the reception side of the electrical signal, respectively. That is, by improving impedance matching of the electrical connection portions of the flexible substrate and the flexible substrate connector, good transmission characteristics can be obtained even in a system that transmits high-speed electrical signals.

  More preferably, the connecting portion is provided on the first main surface of the flexible substrate, and the impedance adjusting portion is provided in a region of the second main surface of the flexible substrate facing the connecting portion. Yes.

  In this way, the impedance adjustment unit is not provided on the electrical connection part of the flexible substrate, for example, the pad side, but the impedance adjustment part is provided on the back surface of the pad. Is set to a different value, uniformity can be ensured for the structure of the connector for the flexible substrate and the electrical connection portion, for example, the pad in the flexible substrate. As a result, contact failure and the like can be reduced and the life of the device can be extended, so that the reliability of the circuit module can be improved.

  More preferably, the impedance adjusting unit is a ground pattern.

  With such a configuration, when the impedance of the flexible board connector is larger than the impedance of the electrical signal transmission path, the impedance of the flexible board and the electrical connection portion of the flexible board connector can be lowered. Impedance matching at the connecting portion can be improved.

  More preferably, the impedance of the transmission path from the ground connection section, which is the connection section with the ground node of the connector, to the ground pattern is greater than the impedance of the transmission path from the ground connection section to the ground node of the connector. large.

  With such a configuration, it is possible to suppress the formation of a return current path via the ground pattern which is the impedance adjustment unit, and the return current flows from the ground pattern on the first main surface of the flexible board to the flexible board connector. Therefore, transmission characteristics can be improved.

  More preferably, the device includes a transmitting device for transmitting an electrical signal and a receiving device for receiving an electrical signal, and the connection portion of the flexible substrate with the connector is the flexible substrate. The impedance of the transmission path of the electrical signal to the transmitting device is smaller than the impedance of the transmission path of the electrical signal from the receiving device, and the impedance adjusting unit is It is a region on the second main surface of the flexible substrate, and is provided in a region facing a connection portion that is a transmission path of an electric signal to the transmission device among the connection portions.

  With such a configuration, the impedance of the transmission path can be varied with a simple configuration on the reception side and the transmission side of the electrical signal.

  Preferably, in the flexible substrate, the connection portion with the connector is provided on the first main surface of the flexible substrate, and the connection portion includes a signal connection portion and a ground connection portion, The ground connection portion is connected to the ground pattern on the first main surface, and the signal connection portion is connected to the second main surface of the flexible substrate through a via.

  With such a configuration, for example, in a configuration in which a flexible board connector is surface-mounted on a rigid board, the distance from the ground pin of the connector to the ground pattern of the flexible board can be shortened. Can be connected to the ground pin without vias, so that the ground potential can be stabilized and the transmission characteristics can be improved.

  Preferably, the device includes a transmitting device for transmitting an electric signal and a receiving device for receiving an electric signal, and the transmitting device and the rigid substrate are electrically connected as the flexible substrate. And a flexible substrate for transmission for electrical connection and a flexible substrate for reception for electrically connecting the receiving device and the rigid substrate are integrated, and the rigid substrate and the above are used as the connector. A transmission connector for detachably connecting the transmission flexible board and a reception connector for detachably connecting the rigid board and the reception flexible board are integrated.

  As described above, the configuration in which the flexible substrate and the flexible substrate connector are integrated on the electrical signal transmission side and the reception side, respectively, can reduce the component cost, and the mounting work can be halved to reduce the processing cost. it can.

  An optical communication apparatus according to an aspect of the present invention includes an optical device that converts an electrical signal into an optical signal and transmits the received optical signal or converts the electrical signal into an electrical signal, and the electrical signal to the optical device. A rigid substrate for optical communication for transmitting or transmitting an electrical signal from the optical device, a flexible substrate for electrically connecting the optical device and the rigid substrate for optical communication, and the optical communication A rigid board for optical communication, a connector for detachably connecting the rigid board for optical communication and the flexible board, and an electric signal to be converted into the optical signal, and output to the rigid board for optical communication Or a processing unit for processing an electrical signal transmitted from the optical device transmitted by the rigid board for optical communication.

  As described above, the connection between the flexible substrate and the rigid substrate for optical communication is not performed by soldering but by the connector, so that an optical device having a short life and easily damaged can be detached from the rigid substrate for optical communication. it can. That is, it is possible to prevent the entire optical communication module including the rigid substrate for optical communication due to the failure of the optical device from being discarded and replaced, and to reduce the processing cost for soldering or the like. Therefore, a flexible substrate can be effectively used in a configuration that performs at least one of transmission and reception of electrical signals.

  According to the present invention, a flexible substrate can be effectively used in a configuration that performs at least one of transmission and reception of an electrical signal.

It is a figure which shows the structure of the PON system which concerns on embodiment of this invention. It is a figure which shows the structure of ONU in the PON system which concerns on embodiment of this invention. It is a figure which shows the structure of the optical communication module in ONU which concerns on embodiment of this invention. It is a figure which shows an example of the external appearance of the optical communication module which concerns on embodiment of this invention. It is a figure which shows an example of the connection form of TOSA, ROSA, a flexible substrate, and the rigid board | substrate for optical communication in the optical communication module which concerns on embodiment of this invention. It is a figure which shows the structure of a part of flexible substrate for transmission in the optical communication module which concerns on embodiment of this invention. It is a figure which shows notionally the layer structure of the flexible substrate for transmission in the optical communication module which concerns on embodiment of this invention. It is a figure which shows an example of the result of having performed signal transmission using a flexible substrate, and evaluating the impedance of a transmission line. It is a figure which shows the other example of the result of having performed signal transmission using a flexible substrate, and evaluating the impedance of a transmission line. It is a figure which shows the structure of a part of flexible substrate for a reception in the optical communication module which concerns on embodiment of this invention. It is a figure which shows notionally the layer structure of the flexible substrate in the optical communication module which concerns on embodiment of this invention. It is a figure which shows the return current which generate | occur | produces in TOSA and the flexible substrate for transmission in the optical communication module which concerns on embodiment of this invention. It is a figure which shows an example of the return current countermeasure in the flexible substrate for transmission in the optical communication module which concerns on embodiment of this invention. It is a figure which shows an example of the external appearance of the modification of the optical communication module which concerns on embodiment of this invention. It is a figure which shows an example of the connection form of TOSA, ROSA, a flexible substrate, and the rigid board | substrate for optical communications in the modification of the optical communication module which concerns on embodiment of this invention. It is a figure which shows an example of the signal line in the flexible substrate for transmission of the optical communication module which concerns on embodiment of this invention. It is a figure which shows the other example of the signal line in the flexible substrate for transmission of the optical communication module which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is a diagram showing a configuration of a PON system according to an embodiment of the present invention.

  Referring to FIG. 1, a PON system 301 is, for example, 10G-EPON, and includes ONUs 202A, 202B, and 202C, a station-side device 201 connected to an upper network, and a splitter SP. The ONUs 202A, 202B, 202C and the station side device 201 are connected via the splitter SP and the optical fiber OPTF, and transmit / receive optical signals to / from each other.

  FIG. 2 is a diagram showing the configuration of the ONU in the PON system according to the embodiment of the present invention.

  Referring to FIG. 2, the ONU 202 includes an optical communication module 101, a PON reception processing unit 92, a buffer memory 93, a UN transmission processing unit 94, a UNI (User Network Interface) port 95, and a UN reception processing unit 96. A buffer memory 97, a PON transmission processing unit 98, and a control unit 99.

  The optical communication module 101 is detachable from the ONU 202. The optical communication module 101 receives a downstream optical signal transmitted from the station-side device 201, converts it into an electrical signal, and outputs it.

  The PON reception processing unit 92 reconstructs a frame from the electrical signal received from the optical communication module 101 and distributes the frame to the control unit 99 or the UN transmission processing unit 94 according to the type of the frame. Specifically, the PON reception processing unit 92 outputs the data frame to the UN transmission processing unit 94 via the buffer memory 93 and outputs the control frame to the control unit 99.

  The control unit 99 generates a control frame including various control information and outputs it to the UN transmission processing unit 94.

  The UN transmission processing unit 94 transmits the data frame received from the PON reception processing unit 92 and the control frame received from the control unit 99 to a user terminal such as a personal computer (not shown) via the UNI port 95.

  The UN reception processing unit 96 outputs the data frame received from the user terminal via the UNI port 95 to the PON transmission processing unit 98 via the buffer memory 97, and the control frame 99 receives the control frame received from the user terminal via the UNI port 95. Output to.

  The control unit 99 performs home-side processing relating to control and management of the PON line between the station-side device 201 and the ONU 202, such as MPCP and OAM. That is, various controls such as access control are performed by exchanging MPCP messages and OAM messages with the station-side apparatus 201 connected to the PON line. The control unit 99 generates a control frame including various control information and outputs it to the PON transmission processing unit 98. The control unit 99 performs various setting processes for each unit in the ONU 202.

  The PON transmission processing unit 98 outputs the data frame received from the UN reception processing unit 96 and the control frame received from the control unit 99 to the optical communication module 101.

  The optical communication module 101 converts the data frame and the control frame, which are electrical signals received from the PON transmission processing unit 98, into optical signals and transmits them to the station-side apparatus 201.

  FIG. 3 is a diagram showing a configuration of the optical communication module in the ONU according to the embodiment of the present invention.

  Referring to FIG. 3, optical communication module 101 includes a burst transmission unit 151 and a reception unit 152. The burst transmission unit 151 includes a preamplifier 86, an output buffer circuit (modulation current supply circuit) 63, a bias current supply circuit 88, and a light emitting circuit 89. The light emitting circuit 89 includes a light emitting element LD and inductors L1 and L2. The receiving unit 152 includes a light receiving element PD, a TIA (transimpedance amplifier) 81, an LIA (limit amplifier) 82, and an output buffer 85.

  In the burst transmission unit 151, the preamplifier 86 receives the transmission data that is the data frame from the UN reception processing unit 96 and the control frame from the control unit 99, and amplifies and outputs the transmission data. For example, the preamplifier 86 receives the transmission data as a differential signal from the signal lines INP and INN.

  The output buffer circuit 87 supplies a modulation current to the light emitting circuit 89 based on the transmission data received from the preamplifier 86. This modulation current is a current having a magnitude corresponding to the logical value of data to be transmitted to the station side device 201.

  The light emitting circuit 89 transmits the upstream optical signal to the station side device 201. In the light emitting circuit 89, the light emitting element LD is connected to a power supply node supplied with a fixed voltage, for example, a power supply voltage Vdd1, via an inductor L1, and is connected to a bias current supply circuit 88 via an inductor L2. The light emitting element LD emits light based on the bias current supplied from the bias current supply circuit 88 and the modulation current supplied from the output buffer circuit 87, and changes the light emission intensity.

  In the receiving unit 152, the light receiving element PD is connected to a power supply node supplied with a fixed voltage, for example, a power supply voltage Vdd2, and converts the optical signal received from the station side device 201 into an electric signal, for example, a current, and outputs it.

  The TIA 81 converts the current received from the light receiving element PD into a voltage and outputs the voltage to the LIA 82.

  The LIA 82 binarizes the voltage level received from the TIA 81 and outputs it as received data.

  The output buffer 85 amplifies the reception data received from the LIA 82 and outputs the amplified data to the PON reception processing unit 92. For example, the output buffer 85 outputs the received data from the signal lines OUTP and OUTN as a differential signal.

  For example, the preamplifier 86, the output buffer circuit 87, the bias current supply circuit 88, the inductors L1 and L2, the TIA 81, the LIA 82, and the output buffer 85 in the light emitting circuit 89 are mounted on a rigid board for optical communication. Yes. Further, the light emitting element LD is built in an assembled light emitting module (hereinafter also referred to as TOSA: Transmitter Optical Sub-Assembly). The light receiving elements PD and TIA 81 are built in an assembled light receiving module (hereinafter also referred to as ROSA: Receiver Optical Sub-Assembly). The rigid board for optical communication and TOSA and ROSA are connected via a flexible printed circuit board (FPC).

  FIG. 4 is a diagram showing an example of the appearance of the optical communication module according to the embodiment of the present invention.

  Referring to FIG. 4, the optical communication module 101 includes a TOSA 11, a ROSA 12, a transmission flexible substrate 13, a reception flexible substrate 14, a transmission connector 15, a reception connector 16, and a rigid substrate for optical communication. 17 and a host connector 18.

  The optical communication module 101 is connected to the optical fiber OPTF via the TOSA 11 and the ROSA 12.

  The optical communication rigid board 17 in the optical communication module 101 is connected to the PON reception processing unit 92, the PON transmission processing unit 98, and the control unit 99 via the host connector 18.

  Some or all of the units other than the optical communication module 101 in the ONU 202 generate, as a processing unit, an electrical signal to be converted into an optical signal and output it to the rigid board 17 for optical communication, and are converted by the light receiving element PD. The electrical signal from the light receiving element PD transmitted by the rigid board 17 for optical communication is processed.

  The light emitting element LD which is an optical device in the TOSA 11 converts an electrical signal into an optical signal and transmits it. This electric signal is an electric signal including transmission data to the station side device 201. For example, the optical signal transmitted by the light emitting element LD is a burst signal having a bit rate greater than 2.48 gigabits / second.

  The light receiving element PD, which is an optical device in the ROSA 12, receives an optical signal and converts it into an electrical signal. This electric signal is an electric signal including data received from the station side device 201.

  The transmission flexible substrate 13 electrically connects the TOSA 11 and the optical communication rigid substrate 17.

  The receiving flexible substrate 14 electrically connects the ROSA 12 and the optical communication rigid substrate 17.

  The transmission connector 15 and the reception connector 16 are provided on a rigid substrate 17 for optical communication, and are mounted on the surface of the rigid substrate 17 for optical communication, for example.

  The transmission connector 15 removably connects the optical communication rigid board 17 and the transmission flexible board 13.

  The receiving connector 16 removably connects the optical communication rigid board 17 and the receiving flexible board 14.

  The optical communication rigid board 17 amplifies the electric signal received from the PON transmission processing unit 98 via the host connector 18 and transmits the amplified signal to the light emitting element LD, or converts it into an electric signal from the light receiving element PD. The signal is amplified and transmitted to the PON reception processing unit 92 via the host connector 18.

  FIG. 5 is a diagram showing an example of the connection form of the TOSA, ROSA, flexible substrate, and optical communication rigid substrate in the optical communication module according to the embodiment of the present invention.

  Referring to FIG. 5, TOSA 11 and transmission flexible substrate 13 are electrically connected by solder, and transmission flexible substrate 13 and optical communication rigid substrate 17 are electrically connected by transmission connector 15. ing. More specifically, when the pad 21 of the transmission flexible board 13 and the pin of the transmission connector 15 are in contact, the transmission flexible board 13 and the optical communication rigid board 17 are electrically connected.

  Further, the ROSA 12 and the receiving flexible board 14 are electrically connected by solder, and the receiving flexible board 14 and the optical communication rigid board 17 are electrically connected by the receiving connector 16. More specifically, when the pads 22 of the receiving flexible board 14 and the pins of the receiving connector 16 are in contact, the receiving flexible board 14 and the optical communication rigid board 17 are electrically connected.

  The light from the optical fiber OPTF and the light from the TOSA 11 are separated by a wavelength filter (not shown) and guided to the ROSA 12 and the optical fiber OPTF, respectively.

  FIG. 6 is a diagram showing a partial structure of the transmitting flexible substrate in the optical communication module according to the embodiment of the present invention.

  The flexible substrate in the optical communication module 101 includes an impedance adjustment unit that adjusts the impedance of an electric signal transmission path in a connection portion, for example, a pad, with the flexible substrate connector. This electric signal is an electric signal to the light emitting element LD or an electric signal from the light receiving element PD. The impedance adjustment unit is, for example, a ground pattern.

  Specifically, referring to FIG. 6, transmission flexible substrate 13 includes pads 31 and 34 as ground connection portions with transmission connector 15 on main surface A, and pad 32 as a signal connection portion. , 33. The pads 31 to 34 correspond to the pad 21 described above.

  On the main surface A of the transmitting flexible substrate 13, the pads 31 and 34 are connected to a ground region provided on the main surface A, that is, a ground pattern 39.

  The pads 32 and 33 are electrically connected to signal lines 41 and 42 provided on the main surface B of the transmitting flexible board 13 through vias 36 and 37, respectively. For example, an electric signal is transmitted to the light emitting element LD via the signal lines 41 and 42, that is, a modulation current is supplied to the light emitting element LD.

  In addition, the transmission flexible substrate 13 includes a ground region, that is, a ground pattern 43 on the main surface B as an impedance adjustment unit. The ground pattern 43 is provided in a region of the main surface B facing the pads 31 to 34. Ground pattern 43 is electrically connected to pads 31 and 34 and main pattern 39 on main surface A through vias 35 and 38.

  FIG. 7 is a diagram conceptually showing the layer structure of the flexible substrate for transmission in the optical communication module according to the embodiment of the present invention. FIG. 7 shows a cross section of the portion of the transmission flexible substrate 13 provided with the pads 21 as viewed from the side of the transmission flexible substrate 13.

  Referring to FIG. 7, the transmission flexible substrate 13 includes a cover PI (polyimide) layer 61, a cover adhesive layer 62, a copper plating layer 64, a copper foil layer 65, a base PI layer 66, and a via 67. The copper foil layer 69, the copper plating layer 70, the cover adhesive layer 71, the cover PI layer 72, the adhesive layer 73, and the reinforcing PI layer 74 are included.

  A cover PI (polyimide) layer 61, a cover adhesive layer 62, a copper plating layer 64, and a copper foil layer 65 are layers on the main surface A side, a copper foil layer 69, a copper plating layer 70, a cover The adhesive layer 71, the cover PI layer 72, the adhesive layer 73, and the reinforcing PI layer 74 are layers on the main surface B side.

  The pad 21 and the ground pattern 39 are formed in the copper plating layer 64 and the copper foil layer 65, and the signal line 68 and the ground pattern 43 are formed in the copper foil layer 69 and the copper plating layer 70. The signal line 68 corresponds to the signal lines 41 and 42 shown in FIG. 6, and the via 67 corresponds to the vias 36 and 37 shown in FIG.

  For example, the thickness of the cover PI layer 61 is 12.5 micrometers, the thickness of the cover adhesive layer 62 is 25 micrometers, the thickness of the copper plating layer 64 is 15 micrometers, and the thickness of the copper foil layer 65 is The thickness of the base PI layer 66 is 50 micrometers, the thickness of the copper foil layer 69 is 18 micrometers, the thickness of the copper plating layer 70 is 15 micrometers, and the cover adhesive layer 71 The thickness is 25 micrometers, the thickness of the cover PI layer 72 is 12.5 micrometers, the thickness of the adhesive layer 73 is 50 micrometers, and the thickness of the reinforcing PI layer 74 is 92 micrometers. In the completed transmission flexible substrate 13, for example, each adhesive layer is compressed to a thickness smaller than the above numerical value.

  As shown in FIG. 4, when the transmission connector 15 and the reception connector 16 are surface-mounted on the optical communication rigid board 17, the main surface A contacts the transmission connector 15. That is, when the optical communication rigid board 17 is on the lower side, the vertical relationship between the main surfaces A and B is opposite to that in FIG.

  Here, in the PON system 301 that is, for example, 10G-EPON, since the received signal on the optical signal receiving side is weak, it is necessary to set the impedance of the transmission path to be relatively high. On the other hand, on the transmission side of the optical signal, it is necessary to set the impedance of the transmission line to be relatively low in consideration of a loss or the like when the light emitting element LD is driven by current in response to a request for lower voltage of the device.

  Therefore, in the ONU 202, the impedance of the electrical signal transmission path to the optical transmission device, that is, the light emitting element LD, is smaller than the impedance of the electrical signal transmission path from the optical reception device, that is, the light receiving element PD. In other words, the ONU 202 is designed such that the transmission line on the transmission side and the transmission line on the reception side substantially have the impedance relationship as described above. For example, the impedance of the transmission path of the electrical signal from the light receiving element PD is designed to be at least 1.4 times the impedance of the transmission path of the electrical signal to the light emitting element LD. In consideration of manufacturing variations, the impedance of the transmission path of the electrical signal from the light receiving element PD is 1.2 to 2.8 times the impedance of the transmission path of the electrical signal to the light emitting element LD. It is also preferable to implement in the range. In the following example, an example in which the impedance of the transmission path of the electrical signal from the light receiving element PD is twice the impedance of the transmission path of the electrical signal to the light emitting element LD will be described as a preferable example. More specifically, for example, the impedance of the electrical signal transmission path in the transmission connector 15 is smaller than the impedance of the electrical signal transmission path in the reception connector 16.

  FIG. 8 is a diagram illustrating an example of the result of evaluating the impedance of a transmission line by performing signal transmission using a flexible substrate. In FIG. 8, the vertical axis represents normalized impedance z [%], and the horizontal axis represents time [100 ps / div]. Graph G1 shows the case where a flexible substrate without a ground pattern is used on the back surface of the pad mounting surface, and graph G1 shows a flexible substrate with a ground pattern provided on the back surface of the pad mounting surface in the same manner as the transmission flexible substrate 13. The case where it is used is shown.

  Here, it is assumed that the transmission path of the optical signal, for example, the transmission path from the preamplifier 86 to the light emitting element LD is designed for single transmission of, for example, 25Ω.

  Further, a 25Ω single-ended signal is applied to one end of the rigid board, the signal is transmitted to the other end of the rigid board via a signal line on the rigid board, and a flexible board connector provided at the other end is provided. The signal is output to one end of the flexible substrate. The other end of the flexible substrate is open. The flexible substrate connector is a general 100Ω balance transmission connector. The rise time and fall time of the signal are set to 20 picoseconds, that is, the bit rate of the signal is 10 gigabits / second or more.

  Referring to FIG. 8, good impedance matching is obtained at portions corresponding to the rigid board and the flexible board, but impedance mismatching occurs in the flexible board connector.

  Specifically, when a flexible substrate that does not have a ground pattern is used on the back surface of the pad mounting surface, an impedance mismatch of 35.7% occurs (graph G1). In addition, when the impedance adjustment is not made in the electrical connection portion of the flexible substrate and the flexible substrate connector, the electrical connection portion may be in a high impedance state.

  On the other hand, when a flexible substrate provided with a ground pattern on the back surface of the pad mounting surface is used, the impedance mismatch is suppressed to 13.6% (graph G2).

  Therefore, it can be seen that, on the optical signal transmission side, by using a flexible substrate provided with a ground pattern on the back surface of the pad mounting surface, the transmission line impedance can be reduced and the transmission characteristics can be improved.

  FIG. 9 is a diagram showing another example of the result of evaluating the impedance of the transmission line by performing signal transmission using a flexible substrate. In FIG. 9, a graph G3 shows a case where a flexible substrate without a ground pattern is used on the back surface of the pad mounting surface, and a graph G4 shows a flexible circuit in which a ground pattern is provided on the back surface of the pad mounting surface in the same manner as the transmission flexible substrate 13. The case where a substrate is used is shown. The other views are the same as in FIG.

  Here, it is assumed that the transmission path from the optical signal receiving side, for example, the light receiving element PD to the output buffer 85 is designed for 100Ω balanced transmission, for example.

  Also, a 100Ω differential signal is applied to one end of the rigid board, the signal is transmitted to the other end of the rigid board via a signal line on the rigid board, and a flexible board connector provided at the other end is provided. The signal is output to one end of the flexible substrate. The other end of the flexible substrate is open. The flexible substrate connector is a general 100Ω balance transmission connector. The rise time and fall time of the signal are set to 20 picoseconds, that is, the bit rate of the signal is 10 gigabits / second or more.

  Referring to FIG. 9, good impedance matching is obtained at portions corresponding to the rigid board and the flexible board, but impedance mismatching occurs in the flexible board connector.

  Specifically, when a flexible substrate provided with a ground pattern on the back surface of the pad mounting surface is used, an impedance mismatch of -10.8% occurs (graph G4).

  On the other hand, when a flexible substrate without a ground pattern on the back surface of the pad mounting surface is used, the impedance mismatch is suppressed to −5.25% (graph G3).

  Therefore, it can be seen that, on the optical signal receiving side, when a flexible substrate provided with a ground pattern on the back surface of the pad mounting surface is used, the impedance of the transmission path is reduced and the transmission characteristics are deteriorated.

  Therefore, as described above, in the optical communication module 101, the impedance adjustment unit is an area on the main surface B of the transmission flexible substrate 13, and the electrical signal to the optical transmission device, that is, the light emitting element LD in each pad 21. It is provided in a region facing the pad 21 serving as a transmission path.

  On the other hand, unlike the transmission flexible substrate 13, the reception flexible substrate 14 is not provided with a ground pattern as an impedance adjustment unit.

  FIG. 10 is a diagram showing a part of the structure of the receiving flexible substrate in the optical communication module according to the embodiment of the present invention.

  Referring to FIG. 10, receiving flexible substrate 14 includes pads 51 to 54 as a connection portion with receiving connector 16 on main surface A.

  On the main surface A of the receiving flexible substrate 14, pads 51 and 54 corresponding to the above-described pads 22 are connected to a ground region provided on the main surface A, that is, a ground pattern 59.

  Pads 52 and 53 are electrically connected to signal lines 45 and 46 provided on main surface B of receiving flexible substrate 14 via vias 56 and 57, respectively. For example, an electric signal from the light receiving element PD is transmitted to the LIA 82 via the signal lines 45 and 46. More specifically, the voltage converted by the TIA 81 is supplied to the LIA 82.

  The layer configuration of the receiving flexible substrate 14 is the same as the layer configuration of the transmitting flexible substrate 13 shown in FIG.

  FIG. 11 is a diagram conceptually showing the layer structure of the flexible substrate in the optical communication module according to the embodiment of the present invention. FIG. 11 shows a cross section of the portion of the flexible substrate provided with the pad as seen along the extending direction of the flexible substrate. In FIG. 11, the transmission flexible substrate 13 and the reception flexible substrate 14 are collectively shown for easy explanation. In addition, portions corresponding to each signal of the differential signal are collectively shown.

  Referring to FIG. 11, in the transmission flexible substrate 13, the copper foil layer 69 and the copper plating layer 70 on the main surface B facing the pads 21 on the main surface A with which the optical signal transmission pin (TX) contacts. A ground pattern 43 is provided in the region.

  On the other hand, in the receiving flexible substrate 14, the pad 22 on the main surface A with which the optical signal transmission pin (RX) contacts, the copper foil layer 69 on the main surface B and the region 75 of the copper plating layer 70 facing each other, No ground pattern is provided.

  Of the copper foil layer 69 and the copper plating layer 70, the area of the copper foil layer 69 and the copper plating layer 70 on the main surface B facing the pad on the main surface A that the ground pin (GND) contacts is as follows: For example, although it is a ground pattern, the structure which is not a ground pattern is also possible.

  As described above, in the optical communication module 101, the electrical connection portion of the flexible substrate and the connector for the flexible substrate is determined by properly using the optical signal transmission side and the reception side whether or not the ground pattern is provided on the back surface of the pad of the flexible substrate. The impedance of the optical signal transmission path is corrected as appropriate.

  FIG. 12 is a diagram illustrating a return current generated in the TOSA and the flexible transmission board in the optical communication module according to the embodiment of the present invention.

  Referring to FIG. 12, when current I is supplied to light emitting element LD via signal lines 41 and 42, return current Ir is generated by a magnetic field and passes through the ground pattern in the vicinity of light emitting element LD. It flows to the ground pattern 39.

  Then, the return current Ir flows from the ground pattern 39 on the main surface A of the transmission flexible substrate 13 to the ground pattern 43 through the via 38, and the ground pattern 39 on the main surface A of the transmission flexible substrate 13 through the via 35. To flow. Then, there is a possibility that the transmission characteristic of the optical signal is deteriorated by the return current Ir.

  Therefore, in the optical communication module 101, in a state where the transmission flexible board 13 and the transmission connector 15 are connected, a ground connection that is a connection portion between the ground node of the transmission connector 15, specifically, a ground pin. The impedance of the transmission path from the part, that is, the pads 31 and 34 to the ground pattern 39 is set larger than the impedance of the transmission path from the ground connection section to the ground node of the transmission connector 15.

  FIG. 13 is a diagram showing an example of a countermeasure against return current in the transmission flexible substrate in the optical communication module according to the embodiment of the present invention. The contents other than those described below are the same as the contents of FIG.

  Referring to FIG. 13, pattern notch 49 for electrically separating ground pattern 43 between ground pads 31 and 34 is provided on main surface B of transmission flexible substrate 13.

  As a result, the current path between the vias 35 and 38 via the ground pattern 43 is interrupted. Then, for example, the return current Ir does not flow from the ground pattern 39 on the main surface A of the transmission flexible board 13 to the ground pattern 43, but from the ground pattern 39 on the main surface A of the transmission flexible board 13 to the ground of the transmission connector 15. Will flow to the pins.

  FIG. 14 is a diagram showing an example of the appearance of a modification of the optical communication module according to the embodiment of the present invention.

  Referring to FIG. 14, the optical communication module 101 includes a TOSA 11, a ROSA 12, a flexible substrate 10, a transmission / reception connector 20, an optical communication rigid substrate 17, and a host connector 18.

  In this modification, as compared with the example shown in FIG. 4, the transmission flexible substrate 13 for electrically connecting the TOSA 11 and the optical communication rigid substrate 17, and the ROSA 12 and the optical communication rigid substrate 17 are electrically connected. The flexible substrate for reception 14 for connecting to the substrate is integrated as a flexible substrate 10.

  Compared to the example shown in FIG. 4, the transmission connector 15 for detachably connecting the optical communication rigid board 17 and the transmission flexible board 13, the optical communication rigid board 17, and the reception flexible board 14. Are connected as a connector 20 for transmission / reception.

  FIG. 15 is a diagram illustrating an example of a connection form of TOSA, ROSA, a flexible substrate, and a rigid substrate for optical communication in a modification of the optical communication module according to the embodiment of the present invention.

  Referring to FIG. 15, TOSA 11 and ROSA 12 and flexible substrate 10 are electrically connected by solder, and flexible substrate 10 and optical communication rigid substrate 17 are electrically connected by transmission / reception connector 20. Yes. More specifically, the flexible substrate 10 and the optical communication rigid substrate 17 are electrically connected when the pads 23 of the flexible substrate 10 and the pins of the transmission / reception connector 20 come into contact with each other.

  FIG. 16 is a diagram illustrating an example of signal lines on the transmission flexible substrate of the optical communication module according to the embodiment of the present invention.

  Referring to FIG. 16, the flexible board connector is generally designed for balanced transmission, and the flexible board connector pins include, for example, ground pins (G), signal pins (S), The signal pins (S) and the ground pins (G) are arranged in this order.

  When the balanced transmission is adopted as the optical signal transmission method, for example, the width of the pad 21 of the transmission flexible substrate 13 is set to a size corresponding to the interval of one pin 81 of the transmission connector 15.

  FIG. 17 is a diagram illustrating another example of signal lines on the transmission flexible substrate of the optical communication module according to the embodiment of the present invention.

  Referring to FIG. 17, when single transmission is adopted as the optical signal transmission method as compared to the case shown in FIG. 16, two signal pins (S) arranged side by side on the flexible board connector are used. Therefore, for example, the width of the signal pad 21 of the transmitting flexible substrate 13 can be made larger than that shown in FIG.

  The characteristic impedance Z of the transmission line in the flexible substrate is represented by the square root of (L / C).

  Here, the value of L is determined by parameters such as the line width, and the value of C is determined by parameters such as the distance between the signal line and the ground.

  As the width of the signal line is increased, L is reduced and the impedance Z of the transmission line can be reduced. That is, it is easy to lower the impedance of the transmission line by adopting the single transmission on the optical signal transmission side.

  Incidentally, in the field of optical communications, there is a demand for downsizing of various devices, and it is desired to use a flexible substrate effectively.

  Therefore, in the optical communication module according to the embodiment of the present invention, the optical device converts an electrical signal into an optical signal and transmits it, or receives an optical signal and converts it into an electrical signal. The optical communication rigid board 17 transmits an electrical signal to the optical device or transmits an electrical signal from the optical device. The flexible substrate electrically connects the optical device and the optical communication rigid substrate 17. The flexible board connector is provided on the optical communication rigid board 17 and detachably connects the optical communication rigid board 17 and the flexible board.

  In this way, the connection between the flexible substrate and the optical communication rigid substrate 17 is not performed by soldering but by a connector, so that an optical device having a short life and easily fail can be detached from the optical communication rigid substrate 17. be able to. That is, the disposal and replacement of the entire optical communication module 101 including the optical communication rigid board 17 due to the failure of the optical device can be prevented, and the processing cost for soldering or the like can be reduced. Therefore, in the optical communication module according to the embodiment of the present invention, the flexible substrate can be effectively used in the configuration for performing optical communication.

  Here, in an optical communication system such as PON, especially in 10G-EPON, since the received signal on the optical signal receiving side is weak, it is necessary to set the impedance of the transmission line relatively high. Transmission or 50Ω single transmission is adopted. On the other hand, on the transmission side of the optical signal, it is necessary to set the impedance of the transmission line to be relatively low in consideration of a loss or the like when the light emitting element is driven by current in response to a request for lowering the voltage of the device. System balanced transmission or 25Ω single transmission is adopted. Specifically, for example, the power supply voltage of the optical communication module 101 is set to 5 V or less.

  That is, in an optical communication system such as PON, it is highly necessary to design the impedance of the transmission path to different values on the optical signal reception side and transmission side.

  On the other hand, in the optical communication module according to the embodiment of the present invention, the flexible substrate includes an impedance adjusting unit for adjusting the impedance of the electric signal transmission path in the connection portion with the connector for the flexible substrate, for example, the pad. .

  With such a configuration, the impedances of the electrical connection portions of the flexible substrate and the flexible substrate connector can be adjusted so as to approach the impedances of the optical signal transmission side and the reception side transmission path, respectively. That is, it is possible to obtain good transmission characteristics even in a high-speed optical communication system by improving impedance matching of the electrical connection portions of the flexible substrate and the flexible substrate connector.

  Here, general-purpose connectors for high-frequency flexible boards often support 100Ω balanced transmission. Such a connector is designed so that the pins are mechanically uniform so that the contact state between the pins and the connection target is uniform for a plurality of pins. Thereby, the impedance at each pin of the connector is constant.

  However, as described above, in an optical communication system such as a PON, it is necessary to design impedances of transmission lines at different values on the optical signal reception side and transmission side. As for, it is necessary to set different impedance for each pin.

  On the other hand, in the optical communication module according to the embodiment of the present invention, the connection portion with the flexible substrate connector is provided on the first main surface of the flexible substrate. The impedance adjustment part is provided in the area | region facing the said connection part of the 2nd main surface of a flexible substrate.

  In this way, the impedance adjustment unit is not provided on the electrical connection part of the flexible substrate, for example, the pad side, but the impedance adjustment part is provided on the back surface of the pad. Is set to a different value, uniformity can be ensured for the structure of the connector for the flexible substrate and the electrical connection portion, for example, the pad in the flexible substrate. Thereby, contact failure etc. can be reduced and the lifetime of an apparatus can be extended, Therefore The reliability of an optical communication module can be improved.

  In the optical communication module according to the embodiment of the present invention, the impedance adjustment unit is a ground pattern.

  With such a configuration, when the impedance of the flexible board connector is larger than the impedance of the optical signal transmission path, the impedance of the flexible board and the electrical connection portion of the flexible board connector can be lowered. Impedance matching at the connecting portion can be improved.

  In the optical communication module according to the embodiment of the present invention, the impedance of the transmission path from the ground connection portion to the ground pattern 43, which is the connection portion with the ground node of the flexible board connector, is flexible from the ground connection portion. It is larger than the impedance of the transmission line to the ground node of the board connector.

  With such a configuration, it is possible to suppress the formation of a return current path through the ground pattern 43 that is the impedance adjustment unit, and to transfer the return current from the ground pattern on the first main surface of the flexible board to the flexible board connector. Since flow can be facilitated, transmission characteristics can be improved.

  In the optical communication module according to the embodiment of the present invention, the impedance of the electrical signal transmission path to the optical transmission device, that is, the light emitting element LD is the same as that of the electrical signal transmission path from the optical reception device, that is, the light receiving element PD. Less than impedance. And the impedance adjustment part is provided in the area | region in the 2nd main surface of a flexible substrate, Comprising: The area | region facing the connection part used as the transmission path of the electrical signal to the device for optical transmission among the said connection parts. .

  With such a configuration, the impedance of the transmission path can be varied with a simple configuration on the reception side and the transmission side of the optical signal.

  In the optical communication module according to the embodiment of the present invention, in the flexible substrate, the signal connection portion and the ground connection portion, which are the connection portions with the flexible substrate connector, are provided on the first main surface of the flexible substrate. ing. The ground connection portion is connected to the ground pattern on the first main surface. The signal connection portions are respectively connected to the second main surface of the flexible substrate through vias.

  With such a configuration, for example, in a configuration in which a flexible board connector is surface-mounted on the optical communication rigid board 17, the distance from the ground pin of the connector to the ground pattern of the flexible board can be shortened. Since the ground pattern of the substrate can be connected to the ground pins without vias, the ground potential can be stabilized and the transmission characteristics can be improved.

  In the optical communication module according to the embodiment of the present invention, the transmission flexible substrate 13 for electrically connecting the optical transmission device and the optical communication rigid substrate 17, the optical reception device, and the optical communication The flexible substrate for reception 14 for electrically connecting the rigid substrate 17 is integrated as the flexible substrate 10. Also, a transmission connector 15 for detachably connecting the optical communication rigid board 17 and the transmission flexible board 13, and a detachable connection between the optical communication rigid board 17 and the reception flexible board 14. The receiving connector 16 is integrated as a transmitting / receiving connector 20.

  As described above, the configuration in which the flexible substrate and the flexible substrate connector are integrated on the optical signal transmitting side and the receiving side, respectively, can reduce the component cost, and the mounting work can be halved to reduce the processing cost. it can.

  In the optical communication module according to the embodiment of the present invention, the impedance adjustment unit is provided on the flexible substrate. However, the present invention is not limited to this. The impedance adjustment unit may be provided in the flexible substrate connector. Specifically, in the flexible substrate connector, the impedance adjustment can be performed by changing the pin interval or the like as the impedance adjustment unit.

  In the optical communication module according to the embodiment of the present invention, the impedance adjustment unit is provided on the connection part of the flexible substrate, that is, the back surface of the pad. However, the present invention is not limited to this. For example, it is possible to adjust the impedance by changing the width of the pad.

  In the optical communication module according to the embodiment of the present invention, the impedance adjustment is performed depending on whether or not the ground pattern is provided on the reception side and the transmission side of the optical signal. However, the present invention is not limited to this. . It is also possible to adjust the impedance by changing the capacitance value by providing a ground pattern on both the reception side and the transmission side of the optical signal and changing the material of each ground pattern.

  In the optical communication module according to the embodiment of the present invention, the optical communication rigid board 17 is configured to be mounted with an amplifier that amplifies an optical signal. However, the present invention is not limited to this. Even if the rigid substrate 17 for optical communication does not amplify the electric signal, it simply transmits the electric signal to the optical device, that is, the light emitting element LD, or simply transmits the electric signal from the optical device, that is, the light receiving element PD. Good.

  In the optical communication module according to the embodiment of the present invention, the burst transmission unit 151 and the reception unit 152 are mounted on the optical communication rigid board 17, but the present invention is not limited to this. In addition to the burst transmitter 151 and the receiver 152, other units shown in FIG. 2 other than the optical communication module 101 may be mounted on the optical communication rigid board 17.

  The optical communication module according to the embodiment of the present invention is an optical communication module used in the ONU 202. However, the present invention is not limited to this, and the optical communication module used in the station-side apparatus 201 may be used. Good.

  Moreover, in the said embodiment, although the optical communication module containing optical devices, such as a light emitting element and a light receiving element, was illustrated, this invention is applicable not only to an optical communication module but to the circuit module containing a certain device. .

  For example, the circuit module according to the present invention is not limited to optical communication but may be used for wireless communication. Alternatively, the circuit module according to the present invention may be used for transmission / reception of electric signals in the apparatus, such as a head for performing data reading or data writing with respect to a recording medium. In addition, since the device included in the circuit module according to the present invention has some physical structure, specifically, it is difficult to directly connect the device and the rigid board with a connector or the like, so a flexible board is used. It is a member that performs at least one of signal transmission and signal reception that is preferably connected to a rigid board.

  That is, in the circuit module according to the present invention, the device transmits or receives an electrical signal. The rigid substrate transmits an electrical signal to the device or transmits an electrical signal from the device. The flexible substrate electrically connects the device and the rigid substrate. And the connector for flexible boards is provided in a rigid board, and connects a rigid board and a flexible board so that attachment or detachment is possible.

  As described above, the connection between the flexible substrate and the rigid substrate is not performed by soldering but by the connector, so that a device having a short life and easily damaged can be detached from the rigid substrate. That is, it is possible to prevent disposal and replacement of the entire circuit module including the rigid board due to device defects, and to reduce processing costs for soldering and the like. Therefore, in the circuit module according to the present invention, the flexible substrate can be effectively used in a configuration that performs at least one of transmission and reception of electric signals.

  Further, in the circuit module according to the present invention, the flexible substrate includes an impedance adjusting unit for adjusting the impedance of the electrical signal transmission path in the connection portion with the flexible substrate connector, for example, the pad.

  With such a configuration, the impedances of the electrical connection portions of the flexible substrate and the flexible substrate connector can be adjusted so as to approach the impedances of the transmission paths on the transmission side and the reception side of the electrical signal, respectively. That is, by improving impedance matching of the electrical connection portions of the flexible substrate and the flexible substrate connector, good transmission characteristics can be obtained even in a system that transmits high-speed electrical signals.

  In the circuit module according to the present invention, the connection portion with the flexible board connector is provided on the first main surface of the flexible board. The impedance adjustment part is provided in the area | region facing the said connection part of the 2nd main surface of a flexible substrate.

  In this way, the impedance adjustment unit is not provided on the electrical connection part of the flexible substrate, for example, the pad side, but the impedance adjustment part is provided on the back surface of the pad. Is set to a different value, uniformity can be ensured for the structure of the connector for the flexible substrate and the electrical connection portion, for example, the pad in the flexible substrate. As a result, contact failure and the like can be reduced and the life of the device can be extended, so that the reliability of the circuit module can be improved.

  In the circuit module according to the present invention, the impedance adjustment unit is a ground pattern.

  With such a configuration, when the impedance of the flexible board connector is larger than the impedance of the electrical signal transmission path, the impedance of the flexible board and the electrical connection portion of the flexible board connector can be lowered. Impedance matching at the connecting portion can be improved.

  In the circuit module according to the present invention, the impedance of the transmission path from the ground connection portion to the ground pattern, which is the connection portion with the ground node of the flexible substrate connector, is the ground node of the flexible substrate connector from the ground connection portion. Greater than transmission line impedance to.

  With such a configuration, it is possible to suppress the formation of a return current path via the ground pattern which is the impedance adjustment unit, and the return current flows from the ground pattern on the first main surface of the flexible board to the flexible board connector. Therefore, transmission characteristics can be improved.

  In the circuit module according to the present invention, the impedance of the transmission path of the electrical signal to the transmission device is smaller than the impedance of the transmission path of the electrical signal from the reception device. The impedance adjustment unit is provided in a region on the second main surface of the flexible substrate, which is a region facing the connection unit serving as a transmission path of an electrical signal to the transmission device among the connection units.

  With such a configuration, the impedance of the transmission path can be varied with a simple configuration on the reception side and the transmission side of the electrical signal.

  In the circuit module according to the present invention, in the flexible substrate, the signal connection portion and the ground connection portion, which are the connection portions with the flexible substrate connector, are provided on the first main surface of the flexible substrate. The ground connection portion is connected to the ground pattern on the first main surface. The signal connection portions are respectively connected to the second main surface of the flexible substrate through vias.

  With such a configuration, for example, in a configuration in which a flexible board connector is surface-mounted on a rigid board, the distance from the ground pin of the connector to the ground pattern of the flexible board can be shortened. Can be connected to the ground pin without vias, so that the ground potential can be stabilized and the transmission characteristics can be improved.

  In the circuit module according to the present invention, the transmitting flexible substrate for electrically connecting the transmitting device and the rigid substrate, and the receiving flexible substrate for electrically connecting the receiving device and the rigid substrate. Are integrated as a flexible substrate. Also, a transmission connector for detachably connecting the rigid board and the transmission flexible board and a reception connector for detachably connecting the rigid board and the reception flexible board are integrated as a transmission / reception connector. Has been.

  As described above, the configuration in which the flexible substrate and the flexible substrate connector are integrated on the electrical signal transmission side and the reception side, respectively, can reduce the component cost, and the mounting work can be halved to reduce the processing cost. it can.

  Here, when the signal handled by the apparatus becomes high speed, it is necessary to prevent deterioration of signal transmission characteristics by connecting the device and the rigid board through an impedance-matched transmission path. For this reason, the structure which connects a device and a rigid board | substrate widely using the flexible substrate which has the structure of a microstrip line instead of a lead wire etc. is employ | adopted widely.

  That is, the circuit module according to the present invention is preferably a signal having a bit rate of 1 gigabit / second or more as a signal to be transmitted or received, and more preferably a signal having a bit rate of 2.4 gigabit / second or more. It is more effective for signals over gigabit / second.

  The above embodiment should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

10 Flexible substrate 11 TOSA
12 ROSA
DESCRIPTION OF SYMBOLS 13 Transmission flexible board 14 Reception flexible board 15 Transmission connector 16 Reception connector 17 Optical communication rigid board 18 Host connector 20 Transmission / reception connector 21-23, 31-34, 51-54 Pad 35-38, 67 Via 39, 43 Ground pattern 41, 42, 45, 46 Signal line 49 Pattern notch 61, 72 Cover PI layer 62, 71 Cover adhesive layer 64, 70 Copper plating layer 65, 69 Copper foil layer 66 Base PI layer 73 Adhesive layer 74 Reinforced PI layer 75 Area 81 TIA
82 LIA
85 Output buffer 86 Preamplifier 87 Output buffer circuit (modulation current supply circuit)
88 Bias current supply circuit 89 Light emission circuit 92 PON reception processing unit 93 Buffer memory 94 UN transmission processing unit 95 UNI port 96 UN reception processing unit 97 Buffer memory 98 PON transmission processing unit 99 Control unit 101 Optical communication module (circuit module)
151 Burst transmission unit 152 Reception unit 201 Station side device 202A, 202B, 202C ONU
301 PON System SP Splitter OPTF Optical Fiber A, B Main Surface L1, L2 Inductor LD Light Emitting Element PD Light Receiving Element

Claims (8)

A device for transmitting or receiving electrical signals;
A rigid board for transmitting electrical signals to the device or transmitting electrical signals from the device;
A flexible substrate for electrically connecting the device and the rigid substrate;
Provided on the rigid board, comprising a connector for detachably connecting the rigid board and the flexible board ,
In the flexible substrate, a connection portion with the connector is provided on the first main surface, and an impedance adjustment portion for adjusting the impedance of the transmission path of the electric signal in the connection portion is on the second main surface, A circuit module provided in a region facing the connecting portion . The circuit module according to claim 1 , wherein the impedance adjustment unit is a ground pattern. The impedance of the transmission path from the ground connection section, which is the connection section with the ground node of the connector, to the ground pattern is larger than the impedance of the transmission path from the ground connection section to the ground node of the connector. 2. The circuit module according to 2 . The device includes a transmitting device for transmitting an electrical signal and a receiving device for receiving an electrical signal,
The connection portion with the connector in the flexible substrate is provided on the first main surface of the flexible substrate,
The impedance of the transmission path of the electrical signal to the transmitting device is smaller than the impedance of the transmission path of the electrical signal from the receiving device,
The impedance adjusting unit is provided in a region on the second main surface of the flexible substrate, the region facing the connecting portion serving as a transmission path of an electric signal to the transmitting device in the connecting portion. the circuit module according to any one of claims 1 to 3. The flexible board includes the connection portion, a ground connection portion, a signal connection portion serving as a transmission path of an electrical signal from the receiving device, and a ground connection portion.
The circuit module according to claim 4, wherein a region of the second main surface facing the signal connection portion has no ground pattern. The front Symbol connecting portion, and the signal connection part, there is a ground connection part,
The ground connection portion is connected to a ground pattern on the first main surface,
The circuit module as claimed in any one of the signal connection portion through the via are connected to the second major surface of the flexible substrate, claims 1 to 5. The device includes a transmitting device for transmitting an electrical signal and a receiving device for receiving an electrical signal,
As the flexible substrate, a transmitting flexible substrate for electrically connecting the transmitting device and the rigid substrate, and a receiving flexible substrate for electrically connecting the receiving device and the rigid substrate; Are integrated,
The connector includes a transmission connector for detachably connecting the rigid board and the transmission flexible board, and a reception connector for detachably connecting the rigid board and the reception flexible board. are integrated, the circuit module according to any one of claims 1 to 6. An optical device for converting an electrical signal into an optical signal for transmission or receiving an optical signal for conversion into an electrical signal;
A rigid substrate for optical communication for transmitting an electrical signal to the optical device or transmitting an electrical signal from the optical device;
A flexible substrate for electrically connecting the optical device and the rigid substrate for optical communication;
A connector for detachably connecting the optical communication rigid board and the flexible board, provided on the optical communication rigid board,
A processing unit for generating an electrical signal to be converted to the optical signal and outputting the electrical signal to the rigid board for optical communication or processing an electrical signal from the optical device transmitted by the rigid board for optical communication; equipped with a,
In the flexible substrate, a connection portion with the connector is provided on the first main surface, and an impedance adjustment portion for adjusting the impedance of the transmission path of the electric signal in the connection portion is on the second main surface, An optical communication device provided in a region facing a connection unit .

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