JP2019186379A - Optical module - Google Patents

Abstract

To allow for compaction while avoiding characteristic impedance mismatch.SOLUTION: An optical module has a conductive stem 10 having a through hole 20 penetrating from the first face 16 to the second face 18, a photoelectric element 56 fixed to the stem 10 on the first face 16, a lead pin 26 placed on the inside of the through hole 20 in non-contact with the stem 10 and electrically connected with the photoelectric element 56, and an insulating board 36 fixed to the stem 10 on the first face 16, and holding one or a pair of lead pins 26 on the outside of the through hole 20. The inner peripheral surface 22 of the through hole 20 and the outer peripheral surface 28 of the lead pins 26 are separated by a cavity so as not to be coupled mutually in th opposite area. The inner peripheral surface 22 is a shield surface, and a transmission line is configured with a characteristic impedance according to the dielectric constant of a medium interposed between the inner peripheral surface 22 and the outer peripheral surface 28.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an optical module.

  Currently, most of the Internet and telephone networks are constructed by optical communication networks. Optical modules used as interfaces for routers / switches and transmission devices that are optical communication devices have an important role in converting electrical signals into optical signals.

  A TO-CAN (Transistor Outline-Can) type optical module used in optical communication generally has a stem that is electrically grounded and a lead pin that penetrates the stem and is insulated from the stem. . Moreover, the housing | casing which accommodates an optical semiconductor element is comprised by the stem and the cap attached to a stem. The lead pin and the stem constitute a coaxial line. One end of the lead pin is connected to the optical semiconductor element. The other end of the lead pin is connected to a driving device that outputs a modulated electric signal through a wiring board such as a flexible printed circuit (FPC) having a signal line and a ground formed along the signal line. .

JP 2007-88233 A JP 2004-253419 A US Patent Application Publication No. 2015/0253520

  The lead pin is held and insulated by glass filled in the through hole of the stem (Patent Documents 1 and 2). The relative permittivity of glass is 4 to 7, and a physical space is required to match the characteristic impedance of the glass coaxial portion to a desired value. For example, in order to provide a coaxial line matched to 50Ω with glass having a relative dielectric constant εr = 6.7, a through hole having a diameter of 2 mm or more is required. Therefore, downsizing has become difficult.

  Patent Document 1 discloses that a glass is not provided in a part of a through-hole and a cavity is formed. Since the cavity has a low relative dielectric constant, the characteristic impedance can be partially increased, but mismatching may also occur.

  Patent Document 2 discloses that the diameter of a portion that becomes a cavity of a through hole is reduced to eliminate mismatching, but there is a problem that glass filling control is difficult.

  Patent Document 3 discloses that a carrier on which an optical semiconductor element is mounted is directly connected to an FPC with a bonding wire. However, there are problems such as difficulty in hermetic sealing, high gold plating for wire bonding and high cost, and the absence of lead pins necessitates a wide variety of FPC connectors in assembly and inspection processes.

  An object of the present invention is to enable miniaturization while avoiding mismatching of characteristic impedance.

  (1) An optical module according to the present invention includes a conductive stem having a first surface and a second surface opposite to each other and having a through hole penetrating from the first surface to the second surface, and the stem A photoelectric element that is fixed on the first surface side and converts an optical signal and an electrical signal from at least one to the other, and the stem is disposed in a non-contact manner inside the through hole, and the photoelectric element One or a pair of lead pins that are electrically connected; and an insulating substrate that is fixed to the stem on the first surface side and that holds the one or pair of lead pins outside the through hole. The through hole has an inner peripheral surface, the one or the pair of lead pins has an outer peripheral surface, and the inner peripheral surface and the outer peripheral surface are separated by a gap so as not to be connected to each other in the opposing region. The inner peripheral surface is a shield surface, and the inner peripheral surface In the characteristic impedance in accordance with the dielectric constant of a medium interposed between the outer peripheral surface, characterized in that the transmission line is configured.

  According to the present invention, since the lead pin and the stem are separated by the air gap, a desired characteristic impedance can be obtained according to a medium having a low dielectric constant (that is, the air gap), and miniaturization can be achieved while avoiding the mismatch of the characteristic impedance. Can be possible.

  (2) In the optical module described in (1), the one or the pair of lead pins is one lead pin, and the inner peripheral surface and the one lead pin constitute a coaxial line. It is good.

  (3) In the optical module described in (1), the one or the pair of lead pins is a pair of lead pins, and the inner peripheral surface has a pair of opposed surface regions, The lead pins may be arranged in a direction along the pair of opposed surface regions, and the pair of surface regions and the pair of lead pins may constitute a differential line.

  (4) The optical module according to any one of (1) to (3), wherein the insulating substrate is fixed to the first surface.

  (5) The optical module according to (4), wherein the insulating substrate has a conductive pad facing the through hole and not contacting the stem on a third surface facing the first surface. The lead pin may be bonded to the conductive pad.

  (6) The optical module according to (5), wherein the insulating substrate has a fourth surface opposite to the third surface, and an electrode electrically connected to the conductive pad is the fourth surface. The photoelectric element may be mounted on the fourth surface and electrically connected to the electrode.

  (7) The optical module according to (4), wherein the insulating substrate has a third surface facing the first surface, and a fourth surface opposite to the third surface, The lead pin may have a protruding portion that penetrates the insulating substrate and protrudes from the fourth surface.

  (8) The optical module according to (7), further including a second insulating substrate having an electrode pattern to which the photoelectric element is electrically connected, wherein the lead pin is the protrusion, solder and The electrode pattern may be joined by a filler material including a brazing material.

  (9) The optical module according to (8), wherein the stem has a pedestal that protrudes from the first surface, and the pedestal has a pedestal surface that rises from the first surface. The two insulating substrates may be mounted on the pedestal surface.

  (10) In the optical module described in any one of (1) to (3), the stem includes a pedestal that protrudes from the first surface, and the pedestal extends from the first surface. It has a pedestal surface that rises, and the insulating substrate may be fixed to the pedestal surface.

  (11) In the optical module described in (10), the insulating substrate has an electrode pattern in which the photoelectric element is electrically connected to a surface opposite to the pedestal surface, and the lead pins are The protruding portion from the first surface may be joined to the electrode pattern by a filler material including solder and brazing material.

It is a perspective view of the optical module which concerns on 1st Embodiment. It is a perspective view which shows the optical module without a flexible substrate. It is a perspective view of the optical module which removed the cap. FIG. 4 is a plan view of the optical module shown in FIG. 3. FIG. 5 is a cross-sectional view of the optical module shown in FIG. 4 taken along line VV. FIG. 6 is a cross-sectional view of the optical module shown in FIG. 4 taken along line VI-VI. It is a figure which shows the 3rd surface of an insulated substrate. It is a figure which shows the 4th surface of an insulated substrate. It is the IX-IX sectional view taken on the line of the optical module shown in FIG. It is a top view of a flexible substrate. It is the schematic for demonstrating the detail of joining of a flexible substrate and a lead pin. It is the schematic for demonstrating the modification of joining of a flexible substrate and a lead pin. It is a front side perspective view of the optical module which concerns on 2nd Embodiment. It is a back side perspective view of the optical module which concerns on 2nd Embodiment. It is a top view of the flexible substrate used by a 2nd embodiment. It is a XVI-XVI line cross section of the optical module shown in FIG. It is a perspective view of the optical module which concerns on 3rd Embodiment. It is the XVIII-XVIII sectional view of the optical module shown in FIG.

  Hereinafter, embodiments of the present invention will be described specifically and in detail based on the drawings. Members denoted by the same reference numerals in all the drawings have the same or equivalent functions, and repeated description thereof is omitted. Note that the size of the figure does not necessarily match the magnification.

[First Embodiment]
FIG. 1 is a perspective view of an optical module according to the first embodiment. The optical module is a TO-CAN (Transistor Outline-Can) type optical module, which includes a transmitter optical sub-assembly (TOSA) having a light emitting element and a light receiving subassembly (ROSA) having a light receiving element. Sub-Assembly), and a bidirectional module (BOSA: Bidirectional Optical Sub-Assembly) including both a light emitting element and a light receiving element. The optical module has a casing composed of a stem 10 and a cap 12 attached to the stem 10, and has a flexible substrate 62 described later.

  FIG. 2 is a perspective view showing an optical module without the flexible substrate 62. FIG. 3 is a perspective view of the optical module with the cap 12 removed. FIG. 4 is a plan view of the optical module shown in FIG. FIG. 5 is a cross-sectional view of the optical module shown in FIG. 4 taken along line VV. 6 is a cross-sectional view of the optical module shown in FIG. 4 taken along the line VI-VI.

  The optical module has a conductive stem 10. The stem 10 is electrically grounded. The stem 10 has a disk shape with a thickness of 0.5 mm or more, has a flange 14, and has a first surface 16 and a second surface 18 opposite to each other. Due to the presence of the flange 14, the second surface 18 is larger than the first surface 16. The stem 10 has a through hole 20 that penetrates from the first surface 16 to the second surface 18. The through hole 20 has an inner peripheral surface 22. The inner peripheral surface 22 has a pair of opposing surface regions 22a. The space | interval of a pair of surface area | region 22a is 0.6 mm or more. If the opening of the through hole 20 is rectangular, the length of the side (for example, the short side) is 0.6 mm or more, and if the opening of the through hole 20 is circular, the diameter is 0.6 mm or more. The stem 10 can be reduced in size by reducing the through hole 20. A GND pin 24 for grounding is fixed to the stem 10 (for example, the second surface 18). A pair of GND pins 24 are provided on both sides of the through hole 20.

  The optical module has one or a plurality of (for example, two) lead pins 26 for transmitting an electrical signal (high-frequency signal). The diameter of the lead pin 26 is 0.25 mm or more and less than 0.4 mm (for example, 0.3 mm). A pair of lead pins 26 are arranged in a direction along a pair of opposing surface regions 22a. A pair of GND pins 24 are arranged on both sides of the pair of lead pins 26 in the arrangement direction.

  The lead pin 26 is disposed inside the through hole 20 so as not to contact the stem 10. The lead pin 26 penetrates the stem 10 and is insulated from the stem 10. A pair of lead pins 26 is disposed in one through hole 20. The lead pin 26 has an outer peripheral surface 28. The outer peripheral surface 28 and the inner peripheral surface 22 of the through hole 20 are separated by a gap (air). That is, there is no solid between the outer peripheral surface 28 and the inner peripheral surface 22, or even if there is a solid, the outer peripheral surface 28 and the inner peripheral surface 22 are not connected. The inner peripheral surface 22 and the outer peripheral surface 28 are not connected to each other in the facing region.

  A transmission line is configured in the optical module. The transmission line has a characteristic impedance (for example, 50 ohms) according to the dielectric constant of the medium (air) interposed between the inner peripheral surface 22 and the outer peripheral surface 28 with the inner peripheral surface 22 being a shield surface inside the through hole 20. ). The pair of surface regions 22a and the two lead pins 26 constitute a differential line. In other words, a transmission line having a characteristic impedance that is uniquely determined by the inner peripheral surface 22 and the dielectric constant of the medium interposed therebetween is configured. The differential line constitutes a transmission line having the inner peripheral surface 22 as a ground potential. The inner peripheral surface 22 closer to the lead pin 26 is electrically strongly connected. If the distance between the inner peripheral surface 22 on the far side (for example, the inner peripheral surface in contact with the inner peripheral surface 22a in FIG. 1 in the direction perpendicular to the lead pin 26) and the lead pin 26 is long, the strip line (slab line) formed on the circuit board. Can be regarded as equivalent.

  According to the present embodiment, since the lead pin 26 and the stem 10 are separated by a gap (air), a desired characteristic impedance can be obtained according to a medium (air) having a low dielectric constant, and mismatching of the characteristic impedance can be achieved. Avoiding this can enable miniaturization.

  The stem 10 has a second through hole 30. A second lead pin 34 is fixed inside the second through hole 30 by being insulated by a solid medium 32 such as glass. The second lead pin 34 is used for power supply (DC voltage) or the like, and does not require characteristic impedance matching with higher accuracy than transmission of an electric signal.

  The optical module has an insulating substrate 36. The insulating substrate 36 is fixed to the stem 10 on the first surface 16 side. The insulating substrate 36 has a third surface 38 facing the first surface 16 and a fourth surface 40 opposite thereto. A third surface 38 of the insulating substrate 36 is fixed to the first surface 16 of the stem 10.

  FIG. 7 is a view showing the third surface 38 of the insulating substrate 36. The insulating substrate 36 is made of ceramic and has a first conductive pad 42 on the third surface 38. The first conductive pad 42 is in a position facing the through hole 20 and is not in contact with the stem 10 and is not shown in FIGS. 5 and 6 because it is a thin film. The first conductive pad 42 is connected to a first contact 44 that penetrates the insulating substrate 36. The insulating substrate 36 further has a second conductive pad 46 on the third surface 38. The second conductive pad 46 is connected to a second contact 48 that penetrates the insulating substrate 36. As shown in FIGS. 5 to 6, the insulating substrate 36 and the stem 10 are fixed with solder 50. The solder 50 is interposed between the second conductive pad 46 and the stem 10 to electrically connect them, and fixes the insulating substrate 36 to the stem 10.

  FIG. 8 is a view showing the fourth surface 40 of the insulating substrate 36. The insulating substrate 36 has a first electrode 52 connected to the first contact 44 on the fourth surface 40. The first conductive pad 42 and the first electrode 52 are electrically connected via the first contact 44. The insulating substrate 36 has a second electrode 54 connected to the second contact 48 on the fourth surface 40. The second conductive pad 46 and the second electrode 54 are electrically connected via the second contact 48.

  As shown in FIGS. 5 and 6, the insulating substrate 36 holds one or a pair of lead pins 26 outside the through hole 20. The lead pin 26 is bonded to the first conductive pad 42. One lead pin 26 is joined to one first conductive pad 42. For joining, welding (for example, fusion welding) can be applied.

  The optical module includes a photoelectric element 56 for converting an optical signal and an electrical signal from at least one to the other. The photoelectric element 56 is fixed to the stem 10 on the first surface 16 side. Specifically, the insulating substrate 36 is fixed to the first surface 16 of the stem 10, and the photoelectric element 56 is mounted on the fourth surface 40 of the insulating substrate 36. The photoelectric element 56 is mounted so that light is input and output in a direction orthogonal to the first surface 16 (a direction orthogonal to the mounting surface).

  In this embodiment, the optical module is a ROSA and has an integrated circuit chip 58. The integrated circuit chip 58 includes a TIA (Trance Impedance Amplifier) that impedance-converts the photoelectric element 56 and its small signal, amplifies and outputs the voltage signal, and a CDR (Clock Data Recovery) that demodulates data from a clock signal synchronized with the data signal. Etc. are integrated. The integrated circuit chip 58 is mounted on the insulating substrate 36, the back surface of the integrated circuit chip 58 is electrically connected to the second electrode 54 (ground potential), and the stem is connected via the second contact 48 and the second conductive pad 46. 10 is electrically connected. An electronic component 60 such as a capacitor is also mounted on the stem 10. The electronic component 60 is not mounted on the insulating substrate 36 but is directly mounted on the first surface 16 of the stem 10.

  The integrated circuit chip 58 is connected to the first electrode 52 by a wire W1 and is connected to the photoelectric element 56 by a wire W2. The photoelectric element 56 is connected to the first electrode 52 via the integrated circuit chip 58. The lead pin 26 is electrically connected to the photoelectric element 56. The integrated circuit chip 58 is also connected to the electronic component 60 by a wire W3. The electronic component 60 is connected to the second lead pin 34 by the wire W4. The integrated circuit chip 58 is connected to another second lead pin 34 by a wire W5.

  9 is a cross-sectional view of the optical module shown in FIG. 1 taken along the line IX-IX. FIG. 10 is a plan view of the flexible substrate 62. FIG. 11 is a schematic diagram for explaining the details of joining of the flexible substrate 62 and the lead pins.

  The flexible substrate 62 includes an insulating layer 64. The insulating layer 64 has a planar shape in which the end portion 64E protrudes from the main body. For example, the end 64E protrudes from the center of the short side of the rectangular main body. The flexible substrate 62 includes a pair of signal wirings 66. The pair of signal lines 66 are differential transmission lines. The signal wiring 66 is in close contact with the insulating layer 64 and there is no gap between them. The signal line 66 has a signal terminal 66T that is wider than the transmission line. In the pair of signal lines 66, the signal terminal 66T extends from the transmission line in a direction away from each other. The pair of signal terminals 66T of the pair of signal wirings 66 are arranged next to each other so as to reach one end portion 64E of the insulating layer 64. The signal wiring 66 is covered with a first resist layer 68 (see FIG. 11) not shown in FIG. However, the first resist layer 68 avoids the signal wiring 66 in the junction region (signal terminal 66T) with the lead pin 26.

  The flexible substrate 62 includes a ground plane 70. The ground plane 70 is in close contact with the insulating layer 64 and there is no gap between them. A signal wiring 66 and a ground plane 70 are formed on opposite surfaces of the insulating layer 64, respectively. On the insulating layer 64, a GND terminal 72 that is electrically connected to the ground plane 70 is provided on the same side as the signal wiring 66. The ground plane 70 and the GND terminal 72 are electrically connected by a via 74 that penetrates the insulating layer 64. The ground plane 70 is entirely covered with the second resist layer 76. A transmission line is configured on the flexible substrate 62. The transmission line has a characteristic impedance (for example, 50 ohms) according to the dielectric constant of the insulating layer 64 with the ground plane 70 as a shield. The lead pin 26 and the signal wiring 66 have the same characteristic impedance.

  An end portion 64 </ b> E of the insulating layer 64 enters the through hole 20 from the second surface 18. An end portion (signal terminal 66T) of the signal wiring 66 enters the through hole 20 from the second surface 18. The first resist layer 68 does not exist inside the through hole 20. The ground plane 70 does not enter the through hole 20. The flexible substrate 62 is in contact with the inner peripheral surface 22 of the through hole 20 on the surface opposite to the lead pin 26. Specifically, the second resist layer 76 covering the ground plane 70 is in contact with the inner peripheral surface 22. Thereby, the flexible substrate 62 is supported by the stem 10 (through hole 20).

  The signal wiring 66 is joined to the lead pin 26. A pair of signal wirings 66 are joined to the pair of lead pins 26, respectively. The signal wiring 66 and the lead pin 26 are continuously joined inside and outside the through hole 20. A filler material 78 including solder and brazing material is interposed between the signal wiring 66 and the lead pin 26. There is no air gap (air) between the lead pin 26 and the insulating layer 64 at least outside the through hole 20. There is no air gap (air) between the lead pin 26 and the insulating layer 64 even inside the through hole 20.

  Although not shown, the second lead pin 34 may be connected to a flexible board different from the flexible board 62, or is electrically connected to an external printed circuit board or the like without going through the flexible board. It doesn't matter.

  According to the present embodiment, since the gap between the lead pin 26 and the through hole 20 is an air gap (air), the diameter of the through hole for obtaining the same characteristic impedance as compared with the case of being filled with glass. Can be reduced in size. Therefore, it is possible to reduce the size of the stem 10 and the optical module. It should be noted that the same effect can be obtained even when a gas other than air, such as used in a nitrogen sealed environment, is present in the gap. Furthermore, in order to increase the bonding strength between the lead pin 26 and the flexible substrate 62, the effect of the present invention can be obtained even if the entire bonding portion is covered with an insulating resin or the like as long as the gap is not filled with the resin. . When resin is used, it is preferable to increase the size of the air gap (the distance between the outer peripheral surface 28 of the lead pin 26 and the inner peripheral surface 22 of the through hole 20) as much as possible because the size of the through hole 20 can be further reduced. . Furthermore, since a part of the flexible substrate 62 enters the through hole 20 of the stem 10, the characteristic impedance of the flexible substrate 62 is maintained outside the stem 10. Thereby, mismatch of characteristic impedance can be avoided. Note that the GND pin 24 is joined to the GND terminal 72 adjacent to the stem 10 as shown in FIG. The filler material 78 containing solder and brazing material is also used for the joining.

  FIG. 12 is a schematic diagram for explaining a modified example of joining of the flexible substrate and the lead pins. In this example, the flexible substrate 162 has a first resist layer 168 that covers the signal wiring 166 at least at the tip portion that enters the through hole 120. The first resist layer 168 is interposed between the signal wiring 166 and the lead pin 126 next to the filler material 178. The first resist layer 168 serves as a flow stop for the melted filler material 178.

[Second Embodiment]
FIG. 13 is a front perspective view of the optical module according to the second embodiment. FIG. 14 is a rear perspective view of the optical module according to the second embodiment. In this embodiment, the optical module is TOSA.

  The stem 210 includes a disc-shaped eyelet 280 having a thickness of 0.5 mm or more. The eyelet 280 has a plurality of (for example, two) through holes 220. The opening of the through hole 220 is circular. As shown in FIG. 14, a GND pin 224 is fixed to the eyelet 280 between the two through holes 220. The eyelet 280 has a second through hole 230.

  The stem 210 has a pedestal 282 that protrudes from the first surface 216. The pedestal 282 has a pedestal surface 284 that rises from the first surface 216. The pedestal surface 284 is a ceramic substrate on which a spacer 286 is mounted and a photoelectric element 256 is mounted thereon. A wiring pattern 288 is formed on the upper surface of the spacer 286. The insulating substrate 236 is fixed to the pedestal surface 284. The insulating substrate 236 has an electrode pattern 290. The electrode pattern 290 is formed on the surface opposite to the pedestal surface 284. The photoelectric element 256 is electrically connected to the electrode pattern 290 by wires W6 and W7. Specifically, the photoelectric element 256 and the wiring pattern 288 are connected by a wire W6, and the wiring pattern 288 and the electrode pattern 290 are connected by a wire W7. The photoelectric element 256 is mounted so that light is input and output in a direction orthogonal to the first surface 216 (a direction parallel to the mounting surface).

  The lead pin 226 is joined to the electrode pattern 290. The joint is made by a filler material 278 containing solder and brazing material at the protrusion 226a from the first surface 216. The inner peripheral surface 222 of the through hole 220 and one lead pin 226 constitute a coaxial line. The medium between the inner peripheral surface 222 and the lead pin 226 is air. A second lead pin 234 is fixed inside the second through hole 230 by being insulated by a solid medium 232 such as glass.

  FIG. 15 is a plan view of the flexible substrate 262 used in the second embodiment. The insulating layer 264 of the flexible substrate 262 has a planar shape in which a pair of end portions 264E protrude from the main body. For example, the pair of end portions 264E project at a distance from the center of one side (short side) of the rectangular main body. The flexible substrate 262 includes a pair of signal wirings 266 that are in close contact with the insulating layer 264. An end portion (signal terminal 266T) of one signal wiring 266 reaches one end portion 264E of the insulating layer 264. The flexible substrate 262 includes a ground plane 270 that is in close contact with the insulating layer 264. On the same side as the signal wiring 266, the insulating layer 264 is provided with a GND terminal 272 that is electrically connected to the ground plane 270 by a via 274. The GND terminal 272 is between the pair of signal terminals 266T.

  16 is a cross section taken along line XVI-XVI of the optical module shown in FIG. The signal wiring 266 is joined to the lead pin 226. For the joining, a filler metal 278 containing solder and brazing material is used. There is no gap between the lead pin 226 and the insulating layer 264 at least outside the through hole 220. There is no air gap between the lead pin 226 and the insulating layer 264 even inside the through hole 220.

  According to the present embodiment, since a part of the flexible substrate 262 enters the through hole 220 of the stem 210, the characteristic impedance of the flexible substrate 262 is maintained outside the stem 210. Thereby, mismatch of characteristic impedance can be avoided. Other details correspond to the contents described in the first embodiment.

[Third Embodiment]
FIG. 17 is a perspective view of an optical module according to the third embodiment. A first insulating substrate 336 is fixed to the stem 310. The first insulating substrate 336 has a third surface 338 facing the first surface 316 of the stem 310, and the third surface 338 is fixed to the first surface 316.

  The stem 310 has a through hole 320, and a lead pin 326 is disposed inside the through hole 320. The inner peripheral surface 322 of the through hole 320 and one lead pin 326 constitute a coaxial line. The lead pin 326 passes through the first insulating substrate 336 and is fixed to the first insulating substrate 336. For the fixing, a filler metal 378 including solder and brazing material may be used. The lead pin 326 protrudes from the fourth surface 340 of the first insulating substrate 336.

  The stem 310 has a pedestal 382 that protrudes from the first surface 316. The pedestal 382 has a pedestal surface 384 that rises from the first surface 316. The optical module has a second insulating substrate 392. The second insulating substrate 392 is mounted on the pedestal surface 384.

  The lead pin 326 has a protrusion 326 a that protrudes from the fourth surface 340. The lead pin 326 (projection 326a) is joined to the electrode pattern 390. The joint is made by a filler material 378 including solder and brazing material at the protrusion 326a. That is, the lead pin 326 is also fixed to the second insulating substrate 392.

  A spacer 386 is mounted on the pedestal 382 (pedestal surface 384), and the photoelectric element 356 is mounted thereon. A wiring pattern 388 is formed on the upper surface of the spacer 386. The wiring pattern 388 and the photoelectric element 356 are electrically connected by a wire W8. The wiring pattern 388 and the electrode pattern 390 are connected by a wire W9. Through these, the photoelectric element 356 and the lead pin 326 are electrically connected.

  18 is a cross section taken along line XVIII-XVIII of the optical module shown in FIG. The signal wiring 366 is joined to the lead pin 326. For the joining, a filler metal 378 including solder and brazing material is used. There is no gap between the lead pin 326 and the insulating layer 364 at least outside the through hole 320. There is no air gap between the lead pin 326 and the insulating layer 364 even inside the through hole 320.

  According to the present embodiment, since a part of the flexible substrate 362 enters the through hole 320 of the stem 310, the characteristic impedance of the flexible substrate 362 is maintained outside the stem 310. Thereby, mismatch of characteristic impedance can be avoided. Other details correspond to the contents described in the first embodiment.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the configuration described in the embodiment can be replaced with substantially the same configuration, a configuration that exhibits the same operational effects, or a configuration that can achieve the same purpose.

10 stem, 12 cap, 14 flange, 16 first surface, 18 second surface, 20 through hole, 22 inner peripheral surface, 22a surface area, 24 GND pin, 26 lead pin, 28 outer peripheral surface, 30 second through hole, 32 Medium, 34 Second lead pin, 36 Insulating substrate, 38 Third surface, 40 Fourth surface, 42 First conductive pad, 44 First contact, 46 Second conductive pad, 48 Second contact, 50 Solder, 52 First electrode , 54 Second electrode, 56 Photoelectric element, 58 Integrated circuit chip, 60 Electronic component, 62 Flexible substrate, 64 Insulating layer, 64E End, 66 Signal line, 66T Signal terminal, 68 First resist layer, 70 Ground plane, 72 GND terminal, 74 via, 76 second resist layer, 78 filler material, 120 through hole, 126 lead pin, 162 flexible substrate, 166 communication Wiring, 168 first resist layer, 178 filler material, 210 stem, 216 first surface, 220 through hole, 222 inner peripheral surface, 224 GND pin, 226 lead pin, 226a protrusion, 230 second through hole, 232 medium, 234 2nd lead pin, 236 insulation substrate, 256 photoelectric element, 262 flexible substrate, 264 insulation layer, 264E end, 266 signal wiring, 266T signal terminal, 270 ground plane, 272 GND terminal, 274 via, 278 filler material, 280 Eyelet, 282 pedestal, 284 pedestal surface, 286 spacer, 288 wiring pattern, 290 electrode pattern, 310 stem, 316 first surface, 320 through hole, 322 inner peripheral surface, 326 lead pin, 326a protrusion, 336 first insulating substrate, 338 Third surface, 340 Fourth surface, 356 Photoelement , 362 a flexible substrate, 364 an insulating layer, 366 signal lines, 378 filler metal, 382 mount, 384 base face, 386 spacer, 388 wiring pattern 390 electrode pattern 392 second insulating substrate, Wl - W9 wire.

Claims (11)

A conductive stem having a first surface and a second surface opposite to each other and having a through-hole penetrating from the first surface to the second surface;
A photoelectric element fixed to the stem on the first surface side for converting an optical signal and an electrical signal from at least one to the other;
One or a pair of lead pins that are arranged in a non-contact manner with the stem inside the through hole and are electrically connected to the photoelectric element;
An insulating substrate fixed to the stem on the first surface side and holding the one or a pair of lead pins outside the through hole;
Have
The through hole has an inner peripheral surface,
The one or pair of lead pins has an outer peripheral surface,
The inner peripheral surface and the outer peripheral surface are separated by a gap so as not to be connected to each other in the facing region,
An optical module, wherein the inner peripheral surface is a shield surface, and a transmission line is configured with a characteristic impedance according to a dielectric constant of a medium interposed between the inner peripheral surface and the outer peripheral surface. The optical module according to claim 1,
The one or a pair of lead pins is one lead pin,
The optical module, wherein the inner peripheral surface and the one lead pin constitute a coaxial line. The optical module according to claim 1,
The one or a pair of lead pins is a pair of lead pins,
The inner peripheral surface has a pair of opposing surface regions,
The pair of lead pins are arranged in a direction along the pair of opposed surface regions,
The optical module, wherein the pair of surface regions and the pair of lead pins constitute a differential line. An optical module according to any one of claims 1 to 3, wherein
The optical module, wherein the insulating substrate is fixed to the first surface. An optical module according to claim 4, wherein
The insulating substrate has a conductive pad on the third surface facing the first surface, the conductive pad facing the through hole and not in contact with the stem.
The optical module, wherein the lead pin is bonded to the conductive pad. The optical module according to claim 5, wherein
The insulating substrate has a fourth surface opposite to the third surface, and has an electrode electrically connected to the conductive pad on the fourth surface,
The photoelectric module is mounted on the fourth surface and electrically connected to the electrode. An optical module according to claim 4, wherein
The insulating substrate has a third surface facing the first surface, and a fourth surface opposite to the third surface;
The optical module according to claim 1, wherein the lead pin has a protruding portion that penetrates the insulating substrate and protrudes from the fourth surface. The optical module according to claim 7, comprising:
A second insulating substrate having an electrode pattern to which the photoelectric element is electrically connected;
The optical module, wherein the lead pin is joined to the electrode pattern by a filler material including solder and brazing material at the protruding portion. The optical module according to claim 8, comprising:
The stem has a pedestal that protrudes from the first surface;
The pedestal has a pedestal surface rising from the first surface,
The optical module, wherein the second insulating substrate is mounted on the pedestal surface. An optical module according to any one of claims 1 to 3, wherein
The stem has a pedestal that protrudes from the first surface;
The pedestal has a pedestal surface rising from the first surface,
The optical module, wherein the insulating substrate is fixed to the pedestal surface. The optical module according to claim 10, wherein
The insulating substrate has an electrode pattern in which the photoelectric element is electrically connected to a surface opposite to the pedestal surface;
The optical module is characterized in that the lead pin is a protruding portion from the first surface and is joined to the electrode pattern by a filler material including solder and brazing material.

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