JP2006066467A - Laser diode module multilayer substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small and an inexpensive laser diode (LE) module multilayer substrate which realizes optical pickup of little spurious radiation. <P>SOLUTION: A low temperature calcination multilayer substrate or an organic multilayer substrate of a resin material is provided with a light emitting/receiving unit mounting part capable of mounting a light emitting/receiving unit including LD and a light receiving element, and an LD protection component mounting part capable of mounting an LD protection component protecting LD from electrostatic destruction and destruction by surge current. The multilayer substrate incorporates at least a part of circuit elements of a high frequency superposition circuit superimposing a high frequency current on LD, and at least a part of circuit elements of an EMC countermeasure circuit reducing electromagnetic wave noise generated from the high frequency superposition circuit. A coil mounting part mounting the coil of the EMC countermeasure circuit is installed on the surface of the substrate, and the capacitor of the EMC countermeasure circuit is arranged inside the substrate positioned just below the coil mounting part. A connection pattern for the flexible printed board is installed and the pattern is arranged on a substrate face opposite to the light emitting/receiving unit mounting part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a laser diode module multilayer substrate, and more particularly to a substrate structure for forming a semiconductor laser diode module of an optical pickup provided in an optical disc apparatus such as a DVD, CD, or MO drive.

  An optical disc apparatus using an optical disc such as a DVD, CD, or MO as a recording medium includes an optical pickup incorporating a semiconductor laser diode (hereinafter referred to as LD), and records information by irradiating the disc with light generated by the LD. Perform playback.

  In addition to the LD as a component, the optical pickup includes an LD protection component that protects the LD from electrical breakdown due to electrostatic breakdown or surge current, a high-frequency superposition circuit that superimposes a high-frequency current on the drive current of the LD, It may contain EMC countermeasure parts that reduce electromagnetic noise generated from the superimposed circuit, and it also has a flexible printed circuit board and optical parts for mounting and connecting them, a frame that forms the skeleton of the optical pickup, and a shape-preserving part Provided with metal plates, screws, etc.

Further, there are the following patent documents as disclosing optical pickup devices.
JP 2002-184013 A JP 2000-138411 A JP 2001-014720 A

  By the way, in recent years, as with various electronic devices, there has been a strong demand for optical disc apparatuses that are small, thin, high-performance, and low-priced. However, although miniaturization of each component is progressing year by year, it is difficult to sufficiently satisfy these demands with the conventional optical pickup structure.

  Accordingly, the present inventor has studied the structure of the optical pickup and found an improvement in order to further reduce the size, thickness, performance, and cost of the optical pickup.

  That is, conventional optical pickups are generally packaged LD components (light emitting / receiving unit components including a semiconductor laser diode that generates light irradiated to a storage medium and a light receiving element that receives reflected light from the storage medium), and LD protection Components, high-frequency superimposed circuit components and EMC countermeasure components provided as necessary are mounted on a flexible printed circuit board, and these are incorporated in a frame incorporating optical components.

  However, if each component is individually mounted on the flexible printed circuit board and incorporated in this way, a wasteful space tends to be generated when the components are stored in the frame, and further miniaturization is difficult. Further, in the conventional structure in which each component is individually incorporated, it is difficult to shorten the length of the connection line between the LD and the high frequency superimposing circuit, and therefore, it is difficult to generate unnecessary radiation.

  In addition, the life cycle of electronic devices tends to become shorter and there is a need to shorten the time required for product development and design as well as miniaturization and higher functionality. In addition, it takes time and effort to design and adjust the LD and each circuit (components), check the operation, etc., which is disadvantageous in terms of cost.

  Further, these problems cannot be sufficiently solved even by the invention described in the above patent document.

  Accordingly, an object of the present invention is to realize a high-performance optical pickup that is smaller, lower cost, and has less unnecessary radiation.

  In order to achieve the object and solve the problem, a first laser diode module multilayer substrate of the present invention includes a semiconductor laser diode that generates irradiation light to a storage medium and a light receiving element that receives reflected light from the storage medium. A light emitting / receiving unit mounting part capable of mounting a light receiving / emitting unit part, and a laser diode protection part mounting part capable of mounting a laser diode protection part for protecting the semiconductor laser diode from electrical breakdown.

  In an optical pickup that records and reproduces information on a storage medium such as a DVD, CD, or MO, an LD (semiconductor laser diode) that generates irradiation light to the storage medium and a light receiving element that receives reflected light from the storage medium are provided. A light receiving / emitting unit component (for example, a hologram laser diode) is provided.

  The multilayer substrate of the present invention includes a light emitting / receiving unit mounting portion on which such a light receiving / emitting unit component can be mounted, and a laser diode protection component mounting portion on which an LD protection component for protecting the LD from electrical breakdown can be mounted. Here, “electrical breakdown” refers to breakdown due to electrostatic breakdown (breakdown due to electrostatic discharge (ESD)) or surge current. Therefore, LD and LD protection components can be mounted on a substrate as a single unit to form an LD module with LD protection components. This makes the optical pickup smaller than before and simplifies the design and assembly process. It becomes possible to do.

  The multilayer substrate of the present invention can be, for example, a ceramic multilayer substrate, a low-temperature fired multilayer substrate using alumina and a glass component, or an organic multilayer substrate based on a resin material. The organic multilayer substrate includes a composite material substrate in which an inorganic material is mixed with a resin material.

  A second laser diode module multilayer substrate according to the present invention is the first laser diode module multilayer substrate, wherein at least a part of a circuit element of a high-frequency superimposing circuit that superimposes a high-frequency current on an LD drive current, and the high-frequency superimposing circuit In the circuit board, at least a part of the circuit elements of the EMC countermeasure circuit for reducing electromagnetic noise generated from the optical pickup can be built in, thereby making it possible to further reduce the size of the optical pickup.

  According to a third laser diode module multilayer substrate of the present invention, in the second laser diode module multilayer substrate, a coil mounting portion capable of mounting a coil constituting the EMC countermeasure circuit is provided on the substrate surface, and the EMC countermeasure circuit is provided. Is provided in the substrate, and the capacitor is arranged at a position almost immediately below the coil mounting portion.

  An EMC countermeasure circuit that reduces electromagnetic noise generated from a high-frequency superimposing circuit in an optical pickup, for example, forms a filter with a coil and a capacitor and inserts this between a terminal to which an LD drive current is input and the high-frequency superimposing circuit. However, if the coil and the capacitor constituting the filter are mounted apart from each other, the parasitic reactance increases and the filter characteristics are deteriorated.

  On the other hand, according to the third substrate structure of the present invention, the coil and the capacitor forming the filter can be brought close to each other, and the wiring between the coil and the capacitor can be shortened. The resonance frequency of the filter can be shifted to the high frequency side and the notch of the filter can be deepened. Therefore, it is possible to realize a high-performance laser diode module excellent in EMC countermeasures.

  According to a fourth laser diode module multilayer substrate of the present invention, in the first to third laser diode module multilayer substrates, the laser diode module multilayer substrate penetrates the laser diode module multilayer substrate and receives the heat generated from the semiconductor laser diode. A heat radiating via hole is provided in the formation region of the light receiving / emitting unit mounting portion to escape to the side of the substrate surface opposite to the substrate surface on which the light emitting unit mounting portion is provided.

  According to such a fourth substrate structure, by providing the heat radiating via hole in the formation region of the light receiving and emitting unit mounting portion, the heat generated from the LD is released straight (at the shortest distance) to the back surface of the substrate, and The heat dissipation of the LD module can be improved.

  As the heat dissipation via hole, for example, a plated through hole can be filled with a heat conductive material (for example, a conductive resin paste). Further, when it is necessary to ensure higher heat dissipation, it is preferable from the viewpoint of heat dissipation efficiency to form a so-called filled via in which a plating metal is deposited so as to fill the through hole and the plating metal is formed in a columnar shape.

  The fifth laser diode module multilayer substrate of the present invention further comprises a connection pattern for the flexible printed circuit board in the first to fourth laser diode module multilayer substrates, and the light emitting / receiving unit mounting portion is provided as the laser diode module multilayer substrate. The connection pattern for the flexible printed circuit board is provided on the other surface of the laser diode module multilayer substrate.

  Thus, if the light receiving / emitting unit mounting portion is provided on one surface of the substrate and the connection pattern for the flexible printed circuit board is provided on the other surface, the substrate surface can be used efficiently, thereby forming the LD module. The LD module can be miniaturized by reducing the substrate. The light emitting / receiving unit components are mounted on the substrate by, for example, wire bonding. If the light receiving / emitting unit mounting portion and the connection pattern for the flexible printed circuit board are arranged separately on the front and back surfaces of the substrate, the LD When connecting a flexible printed circuit board to the module, the connection work can be performed only on one surface of the substrate provided with the connection pattern, and it is not necessary to touch the substrate surface on the light emitting / receiving unit component mounting side. The possibility of damage to the light emitting / receiving unit parts during handling of the process or the occurrence of a disconnection accident by touching the bonding wire is reduced, and the product yield can be increased.

  According to a sixth laser diode module multilayer substrate of the present invention, a connection pattern for the flexible printed circuit board is arranged on the side edge portion of the laser diode module multilayer substrate. Connection work of the flexible printed circuit board can be facilitated.

  Furthermore, the seventh laser diode module multilayer substrate of the present invention is a substrate that penetrates through the laser diode module multilayer substrate and transmits heat generated from the laser diode opposite to the substrate surface on which the light emitting / receiving unit mounting portion is provided. A heat radiating via hole that escapes to the surface side is provided in a region where the light emitting and receiving unit mounting portion is formed, and connection patterns for the flexible printed circuit board are arranged on both sides of the region where the heat radiating via hole is formed.

  By arranging the connection pattern with respect to the heat dissipation via hole and the flexible printed circuit board in this manner, the flexible printed circuit board with respect to the laser diode module multilayer substrate can be secured in the same manner as the sixth substrate while ensuring good heat dissipation of the LD module. Connection work can be facilitated. Further, by arranging the connection patterns on both sides of the heat-dissipating via hole forming region, the substrate can be miniaturized.

  The eighth laser diode module multilayer substrate of the present invention further comprises an active element mounting portion capable of mounting a semiconductor active element constituting a high frequency superposition circuit for superposing a high frequency current on a driving current of the semiconductor laser diode, and receiving and emitting the light The unit mounting portion is provided on one surface of the laser diode module multilayer substrate, and the active element mounting portion is provided on the other surface of the laser diode module multilayer substrate.

  According to a ninth laser diode module multilayer substrate of the present invention, a reference potential layer is provided between the light emitting / receiving unit mounting portion and the active element mounting portion in the eighth substrate.

  Furthermore, a tenth laser diode module multilayer substrate of the present invention comprises two or more reference potential layers.

  When the LD and the high-frequency superimposing circuit are integrated as a module, there is a concern that the LD may be adversely affected by electromagnetic coupling with the high-frequency superimposing circuit, particularly the semiconductor active element included in the oscillation circuit in the circuit. In contrast, in the ninth substrate structure of the present invention, the light emitting / receiving unit mounting portion is provided on one surface of the laser diode module multilayer substrate, and the active element mounting portion is provided on the other surface. In the ninth substrate structure, by interposing a reference potential layer between the light emitting / receiving unit mounting part (LD) and the active element mounting part (semiconductor active element), the coupling is cut off and the influence on the LD is affected. Can be reduced or eliminated. In order to prevent the influence of the coupling more reliably, it is desirable to provide two or more reference potential layers as in the tenth substrate of the present invention.

  The laser diode module multilayer substrate of the present invention includes DVD (DVD-ROM, DVD-RAM, DVD-R, DVD-RW, etc.), CD (CD-ROM, CD-R, CD-RW, etc.), MD (Mini Disk), MO (magneto-optical disc), optical video disc, optical PCM audio disc, and other optical disc devices that use various optical discs as recording media (combo drive device or DVD capable of recording / reproducing on multiple types of recording media) It can be used as a substrate for forming a laser diode module of an optical pickup provided in a multi-drive device and the like.

  According to the laser diode module multilayer substrate of the present invention, it is possible to realize a high-performance optical pickup that is smaller, lower cost, and has less unnecessary radiation.

  Other objects, features and advantages of the present invention will become apparent from the following description of embodiments of the present invention.

  FIGS. 1 to 5 show a laser diode module configured by using a laser diode module multilayer substrate according to an embodiment of the present invention (hereinafter referred to as this embodiment), and FIGS. 6A to 6D show the embodiment. 1 shows such a laser diode module multilayer substrate. In addition, in each figure, the same code | symbol shows the same or an equivalent part.

  The LD module multilayer substrate according to the present embodiment can constitute the LD module provided in the optical pickup. First, an LD module that can be configured using the substrate of the present embodiment will be described, and then the present module will be described. The LD module multilayer substrate of the embodiment will be described.

  As shown in FIGS. 1 and 2, the LD module 11 that can be configured by the substrate according to the present embodiment has a high frequency to drive current of the hologram laser element 15 (light emitting / receiving unit component) and the LD 15 a included in the hologram laser element 15. The high-frequency superimposing circuit 14 for superimposing current, the EMC countermeasure circuit 13 for reducing electromagnetic wave noise generated from the high-frequency superimposing circuit 14, and the hologram laser element 15 (LD 15 a) from electrical breakdown such as electrostatic breakdown or breakdown due to surge current or the like. The LD protection circuit 16 to be protected is integrated as a module, and each of these elements or circuit components is integrated by being mounted on a substrate (indicated by reference numeral 21 in FIG. 3 and subsequent figures) according to this embodiment. .

  The hologram laser element 15 includes a single mode LD 15a, a light receiving element (not shown), and a hologram element (not shown). The laser light emitted from the LD 15a reaches the optical disk through the hologram element, and the reached laser light is reflected by the optical disk, diffracted by the hologram element and incident on the light receiving element, and information recorded on the disk is recorded. Read.

  The hologram laser element 15 includes a signal line for inputting / outputting a recording / reproducing signal to / from the hologram laser element 15 and LD protection for protecting the LD 15a from electrostatic breakdown (electrostatic discharge / ESD breakdown) or surge current breakdown. A circuit (for example, a varistor) 16 is connected. The signal line can be formed by a flexible printed circuit board (hereinafter referred to as FPC). In addition, the LD module 11 includes, as external connection terminals 12, a power input terminal 12b that supplies a drive current for the LD 15a, a ground terminal 12c, and an output terminal 12a to a PD (photo detector) that monitors and controls the output of the LD 15a. I have.

  The hologram laser element 15 is further connected with a high frequency superimposing circuit 14 between the high frequency circuit 14 and the external connection terminal 12 (power input terminal 12b, ground terminal 12c), and with the external connection terminal 12 (output terminal 12a). An EMC countermeasure circuit 13 is provided between each of the hologram laser elements 15. The high-frequency superposition circuit 14 includes an oscillation circuit and a matching circuit configured by a transistor Q1, a coil L3, capacitors C2 to C6, and resistors R1 and R2. The EMC countermeasure circuit 13 includes a coil L2 and a capacitor C1 connected between the power input terminal 12b and the high frequency superposition circuit 14, and a coil L1 and a capacitor C7 connected between the output terminal 12a and the hologram laser element 15. Constitute. Note that the capacitor C1 included in the EMC countermeasure circuit 13 also functions as a power source stabilization capacitor for allowing the oscillation circuit to operate stably.

  Among the passive elements constituting the high frequency superimposing circuit 14 and the EMC countermeasure circuit 13, the capacitors C1, C2, C3, C4, C5, C6 and the coil L3 are described later with reference to FIGS. 6A to 6D. The capacitor C7 and the coils L1 and L2 are built in the substrate 21 according to the present embodiment, and are mounted on the surface of the substrate 21 according to the present embodiment using chip components.

  3 to 5 show the external configuration of the LD module 11. FIG. 3 shows one surface of the substrate 21 of this embodiment (for the sake of explanation, it is assumed to be the upper surface), and FIG. FIG. 5 shows the other side of the substrate 21 (for the sake of explanation, the lower side). As shown in these drawings, the substrate 21 of the present embodiment has a substantially rectangular shape in a plane, and as shown in FIG. 3, the hologram laser element 15 and the passive elements constituting the EMC countermeasure circuit 13 are formed on the upper surface. A part and the LD protection circuit component 16 can be surface-mounted.

  The hologram laser element 15 can be arranged at a substantially central position in the longitudinal direction of the substrate 21, and the hologram laser element 15 is wire-bonded and mounted at both ends thereof (therefore, both ends in the longitudinal direction of the substrate 21). Conductor patterns 22 are arrayed (bonding wires are not shown, and so on). In addition, a plurality of heat dissipation via holes 23 for releasing heat generated from the LD 15a to the lower surface of the substrate 21 are provided in the lower region of the hologram laser element of the substrate 21 (see FIGS. 6A to 6D).

  These heat radiating via holes 23 are formed in the lower surface of the multilayer substrate through the multilayer substrate 21 through the heat radiating conductor pattern 24 formed on the upper surface of the multilayer substrate 21 in a substantially vertical direction in the mounting region of the hologram laser element 15. It extends to the heat sink connection pattern 25 (described later), and is connected to the heat sink connection pattern 25 so as to allow heat conduction. As described above, the heat radiating via hole 23 is formed, for example, by filling the plated through hole with a conductive resin paste, or by a filled via in which plated metal is deposited in a columnar shape so as to fill the through hole. I can do it.

  On the other hand, on the lower surface of the substrate 21, the transistor Q1 included in the high-frequency superposition circuit 14 and the resistors R1 and R2 are surface-mounted. Further, a heat sink connection pattern 25 is formed at a substantially central position in the longitudinal direction of the substrate 21 so as to correspond to the mounting position of the hologram laser element 15. The heat dissipation connection hole 25 is connected to the heat sink connection pattern 25, and the heat generated by the LD 15a is conducted to the bottom surface of the substrate in a shortest distance substantially straight, and is efficiently radiated to the outside through the heat sink connection pattern 25. Is done.

  With respect to the longitudinal direction of the substrate 21, a conductor pattern for connecting an FPC (flexible printed circuit board) to both sides (both ends in the longitudinal direction of the multilayer substrate 21) of the heat sink connection pattern 25 (region where the heat dissipation via hole 23 is formed). 26 are arranged along the edge of the substrate 21 (the short side of the substrate 21). By arranging the pattern 26 at the end of the substrate in this way, it is possible to easily perform the operation of connecting the FPC to the LD module 11. The number of terminals constituting the FPC connection pattern 26 is preferably the same or substantially the same at the left end and the right end of the substrate 21 from the viewpoint of reducing the size of the substrate 21.

  6A to 6D are views of each layer of the substrate 21 according to the present embodiment as viewed from the upper surface side. In the following description, the upper surface to the lower surface of the substrate are sequentially referred to as the first layer to the twentieth layer. 6D (t) is a view of the wiring layer in the substrate viewed from the upper surface side as in FIGS. 6A (a) to 6D (s). Therefore, FIG. 20 layer) is shown in a transparent state.

  As shown in these drawings, the LD module multilayer substrate according to this embodiment is a low-temperature fired multilayer substrate including 20 wiring layers including both the front and back surfaces of the substrate, and the first layer (substrate upper surface) 21a includes: A hologram laser element mounting portion 31 for mounting the hologram laser element 15 is provided at the center position in the longitudinal direction of the substrate 21. A conductive pattern 24 is formed on the hologram laser element mounting portion 31, and a heat radiating via hole 23 extending through the substrate to the heat sink connection pattern 25 on the lower surface of the substrate is connected to the conductive pattern. The first layer 21a is provided with connection pads 32a to 32e for mounting the surface mount components 13 and 16 shown in FIG. Among these connection pads, the connection pad 32e at the corner of the substrate 21 is for mounting the coil L2 constituting the EMC countermeasure circuit 13.

  On the other hand, the capacitor C1 constituting the EMC countermeasure circuit 13 is formed by a conductor pattern provided on the fourth layer 21d and a ground pattern provided on the third layer 21c and the fifth layer 21e.

  Here, the capacitor C1 is formed at a position substantially directly below L2 (connection pad 32e for the coil L2) that is surface-mounted on the substrate upper surface (first layer) 21a, and is as close as possible to the mounting position of the coil L2. . This is because if the coil L2 and the capacitor C1 constituting the EMC countermeasure circuit 13 are separated from each other, the parasitic reactance increases, and the characteristics of the filter formed by the coil L2 and the capacitor C1 deteriorate. Since the wiring between the coil L2 and the capacitor C1 can be shortened if the connection position of the connection pad 32e on which the coil L2 is mounted and the capacitor C1 are made close as in the substrate 21 of the present embodiment, the parasitic reactance can be reduced. It is possible to further reduce the generation of noise by shifting the resonance frequency of the filter to the high frequency side and deepening the notch of the filter.

  The “substantially directly below position” (same in the claims) does not necessarily mean only a position that is strictly vertically below (directly below), and may be slightly shifted in the horizontal direction. This is because the object of reducing the distance between the coil L2 and the capacitor C1 can be achieved. For the same reason, the capacitor C1 is not necessarily formed in the adjacent lower layer in the vertical direction, and the capacitor C1 may be formed in a layer separated by two or more layers.

  The capacitor C2 constituting the high frequency superimposing circuit 14 has a conductor pattern formed from the thirteenth layer 21m to the eighteenth layer 21r, and the capacitor C3 has a ground pattern provided on the ninth layer 21i and the eleventh layer 21k and the tenth pattern. The conductive patterns provided on the layer 21j and the twelfth layer 21l are respectively formed. Similarly, the capacitor C4 included in the high-frequency superimposing circuit 14 is based on the ground pattern of the ninth layer 21i and the conductor pattern of the tenth layer 21j, and the capacitor C5 is based on the conductor patterns provided on the tenth layer 21j to the thirteenth layer 21m. The capacitor C6 is formed by a conductor pattern and a ground pattern provided on the fifth layer 21e to the ninth layer 21i, respectively. Further, the coil L3 included in the high-frequency superposing circuit 14 is formed by a loop-shaped conductor pattern provided from the fifteenth layer 21o to the eighteenth layer 21r.

  On the lower surface (20th layer) 21t of the substrate, together with the heat sink connection pattern 25 and the FPC connection pattern 26, connection pads 33a, 33b for surface mounting the transistor Q1 and the resistors R1, R2 included in the high frequency superposition circuit 14 are provided. 33c is provided.

  In addition, in order to connect between the conductor pattern and connection pad of each said layer, it can carry out by a plating through hole, for example. Further, each of the conductor patterns such as the FPC connection pattern 26, the connection pads 32 and 33 of the surface mount component, and the conductor pattern inside the substrate can be formed by, for example, a thick film method of printing a conductor paste on the substrate. It is also possible to form it by a thin film method such as.

  In the present embodiment, the substrate 21 is a low-temperature fired multilayer substrate (LTCC substrate) using alumina and a glass component as an insulating layer. However, the substrate 21 is an organic multilayer substrate using a resin material as an insulating base, or an inorganic resin material. It is also possible to use a composite material substrate in which materials are mixed.

  In the circuit of FIG. 2, the high frequency superposition current is input to the LD 15a from the oscillation circuit portions Q1, C2, L3, etc. in the high frequency superposition circuit via the matching elements C4 to C6 and passes through the return path (ground). Return to. Unnecessary radiation is generated by the loop circuit until this high-frequency current leaves the oscillation circuit section and returns. The generation state of the unnecessary radiation basically changes depending on the impedance and the length of the loop circuit and has a relationship with the wavelength. However, the unnecessary radiation increases in proportion to the length. In addition, high-frequency current leaks from other lines connected to the LD 15a and the high-frequency superposition circuit 14, leading to generation of unnecessary radiation. Further, a packaged LD is generally used. In this case, since the package wiring (terminals, etc.) also operates as an antenna, it adversely affects unwanted radiation.

  On the other hand, when the LD module is formed using the substrate of the above embodiment, the high frequency superimposing circuit 14 is mounted on the substrate surface or inside the substrate, and the LD 15a is also directly mounted on the substrate including peripheral components as a module. Since they can be integrated, the shape of the high-frequency current loop circuit and the path through which the high-frequency current leaks (that is, the portion serving as the antenna) can be shortened and reduced. Therefore, unnecessary radiation can be reduced, and it is possible to reduce the size and cost of the optical pickup by eliminating radiation measures such as providing a shield case.

  The embodiments of the present invention have been described above based on the drawings. However, the present invention is not limited to these embodiments, and various modifications can be made within the scope of the claims. Is obvious.

It is a block diagram which shows the LD module which can be comprised using the LD module multilayer substrate concerning one Embodiment of this invention. It is a circuit diagram which shows the LD module which can be comprised using the LD module multilayer substrate of the said embodiment. It is a top view which shows the LD module multilayer substrate (state which mounted the component of LD module) of the said embodiment. It is a side view which shows the LD module multilayer substrate (state which mounted the component of LD module) of the said embodiment. It is a bottom view which shows the LD module multilayer substrate (state which mounted the component of LD module) of the said embodiment. FIG. 6 is a perspective view showing first to fifth layers of the LD module multilayer substrate according to the embodiment. It is a perspective view which shows the 6th layer to the 10th layer of the LD module multilayer substrate of the embodiment. It is a perspective view which shows the 11th layer to the 15th layer of the LD module multilayer substrate of the embodiment. It is a perspective view which shows the 16th layer to the 20th layer of the LD module multilayer substrate of the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Laser diode module 12 External connection terminal 13 EMC countermeasure circuit 14 High frequency superimposition circuit 15 Hologram laser element (light emitting / receiving unit components)
16 LD protection circuit 21 LD module multilayer substrate 21a to 21t Wiring layer of LD module multilayer substrate 23 Heat radiating via hole 25 Heat sink connection pattern 26 FPC connection pattern 31 Hologram laser element mounting part 32a to 32e, 33a to 33c Surface mounting component connection pad

Claims (10)

A light receiving / emitting unit mounting portion capable of mounting a light receiving / emitting unit component including a semiconductor laser diode that generates irradiation light to the storage medium and a light receiving element that receives reflected light from the storage medium;
A laser diode protection component mounting portion capable of mounting a laser diode protection component that protects the semiconductor laser diode from electrical breakdown; and
A laser diode module multilayer substrate comprising: At least a part of a circuit element of a high-frequency superimposing circuit that superimposes a high-frequency current on a driving current of the semiconductor laser diode, and at least a part of circuit elements of an EMC countermeasure circuit that reduces electromagnetic wave noise generated from the high-frequency superimposing circuit. The laser diode module multilayer substrate according to claim 1, wherein the laser diode module multilayer substrate is incorporated in the substrate. A coil mounting portion capable of mounting a coil constituting the EMC countermeasure circuit is provided on the substrate surface,
A capacitor constituting the EMC countermeasure circuit is provided inside the substrate,
The laser diode module multilayer substrate according to claim 2, wherein the capacitor is disposed at a position substantially immediately below the coil mounting portion. The light receiving / emitting unit mounting portion has a heat dissipation via hole that passes through the laser diode module multilayer substrate and releases heat generated from the semiconductor laser diode to the substrate surface side opposite to the substrate surface on which the light receiving / emitting unit mounting portion is provided. The laser diode module multilayer substrate according to any one of claims 1 to 3, wherein the laser diode module multilayer substrate is provided in a formation region. A connection pattern for the flexible printed circuit board is further provided.
The light emitting / receiving unit mounting portion is provided on one surface of the laser diode module multilayer substrate,
The laser diode module multilayer substrate according to any one of claims 1 to 4, wherein a connection pattern for the flexible printed circuit board is provided on the other surface of the laser diode module multilayer substrate. 6. The laser diode module multilayer substrate according to claim 5, wherein a connection pattern for the flexible printed circuit board is arranged on a side edge of the laser diode module multilayer substrate. The light receiving / emitting unit mounting portion has a heat dissipation via hole that passes through the laser diode module multilayer substrate and releases heat generated from the semiconductor laser diode to the substrate surface side opposite to the substrate surface on which the light receiving / emitting unit mounting portion is provided. In the formation region of
The laser diode module multilayer substrate according to claim 6, wherein connection patterns for the flexible printed circuit board are arranged on both sides of a region where the heat dissipation via hole is formed. An active element mounting portion capable of mounting a semiconductor active element that constitutes a high-frequency superposition circuit that superimposes a high-frequency current on the drive current of the semiconductor laser diode;
The light emitting / receiving unit mounting portion is provided on one surface of the laser diode module multilayer substrate,
The laser diode module multilayer substrate according to any one of claims 1 to 7, wherein the active element mounting portion is provided on the other surface of the laser diode module multilayer substrate. The laser diode module multilayer substrate according to claim 8, wherein a reference potential layer is provided between the light emitting / receiving unit mounting portion and the active element mounting portion. The laser diode module multilayer substrate according to claim 9, comprising two or more reference potential layers.

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