JP2019083228A - Light receiving module - Google Patents

Abstract

To provide a light receiving module capable of arranging a photodiode at an appropriate position on the main surface of a stem.SOLUTION: A light receiving module includes a light receiving element 21 that includes a main surface 21a and an opposite surface 21b opposite to the main surface and receives light from the main surface, a carrier 25 that includes a first surface 25b and a second surface 25a opposite to the first surface and in which a light receiving element is mounted on the first surface, an integrated circuit chip 26 that includes a third surface 26a and a fourth surface 26b opposite to the third surface and in which a carrier is mounted on the third surface, a stem 24 in which the integrated circuit chip is mounted on the main surface, and a wiring pattern that is provided on the first surface of the carrier, and in which first and second pads are disposed at both ends, and that connects the light receiving element and the integrated circuit chip.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a light receiving module.

  Patent Document 1 discloses a coaxial type light receiving module attached to an optical fiber. The light receiving module includes a package, a photodiode provided on the top surface of the package, and a preamplifier IC provided on the top surface of the package. The photodiode and the preamplifier IC are electrically connected to the power supply terminal and the signal output terminal fixed to the package via bonding wires.

Patent No. 3623144 gazette

  There is known a coaxial type light receiving module in which a photodiode is mounted on the main surface of a stem intersecting with the optical axis of an optical fiber (see, for example, Patent Document 1). In such a light receiving module, there are cases where the integrated circuit chip such as a preamplifier and the photodiode can not be freely disposed due to the limitation of the area of the main surface of the stem. In particular, such problems become significant as the dimensions of the integrated circuit chip increase due to high functionalization and the like. In such a case, if the position of the photodiode is largely deviated from the central axis of the incident light, the light reception sensitivity is lowered. Conversely, if the position of the photodiode is too close to the central axis of incident light, return light due to reflection on the light receiving surface of the photodiode increases, and optical return loss (ORL) increases.

  The present invention has been made in view of such problems, and it is an object of the present invention to provide a light receiving module capable of arranging a photodiode at an appropriate position on the main surface of a stem.

  In order to solve the problems described above, a light receiving module according to an embodiment has a main surface and an opposite surface opposite to the main surface, and a light receiving element that receives light from the main surface, a first surface and a first The carrier has a second surface opposite to the surface, and has a carrier for mounting the light receiving element on the first surface, a third surface and a fourth surface opposite to the third surface, and the carrier on the third surface The integrated circuit chip to be mounted, the stem on which the integrated circuit chip is mounted on the main surface, the first surface of the carrier provided on the first surface, the first and second pads are disposed at both ends, and the light receiving element and the integrated circuit chip And a wiring pattern to be connected.

  According to the light receiving module according to the present invention, the photodiode can be disposed at an appropriate position on the main surface of the stem.

FIG. 1 is a cross-sectional view showing the configuration of a light receiving module according to an embodiment of the present invention. FIG. 2 is an enlarged side view showing the configuration in the vicinity of the photodiode of the light receiving unit. FIG. 3 is a plan view of the light receiving unit from which the package and the lens are removed. FIG. 4 is a plan view of the second surface of the integrated circuit chip. FIG. 5 is a plan view of the fourth surface of the carrier. FIG. 6 is a plan view showing a carrier according to a first modification. FIG. 7 is a plan view showing a carrier according to a second modification. FIG. 8 is a plan view showing a configuration on a stem in the second modified example. FIG. 9 is a plan view showing a case where an electrode pad and a lead pin are connected via a bonding wire and a plurality of capacitors as a comparative example. FIG. 10 is a plan view showing the configuration on the stem of the light receiving module according to the comparative example. FIG. 11 is a plan view showing the configuration on the stem of the light receiving module according to the comparative example.

Description of the embodiment of the present invention
First, the contents of the embodiment of the present invention will be listed and described. A light receiving module according to an embodiment has a main surface and an opposite surface opposite to the main surface, and a light receiving element that receives light from the main surface, and a first surface and a second surface opposite to the first surface An integrated circuit chip having a carrier on which the light receiving element is mounted on the first surface, a third surface and a fourth surface opposite to the third surface, on which the carrier is mounted on the third surface, And a wiring pattern provided on the first surface of the carrier, the first and second pads disposed at both ends, and connecting the light receiving element and the integrated circuit chip.

  In this light receiving module, the carrier on which the light receiving element is mounted is mounted on the integrated circuit chip. Thus, even in the case where the integrated circuit chip has a large size, the degree of freedom in the arrangement of the light receiving elements can be increased. However, when the distance between the electrode pad of the integrated circuit chip and the light receiving element becomes long, the bonding wire connecting the electrode pad and the light receiving element becomes long, which leads to the deterioration of the waveform of the electric signal. Further, if the distance between the electrode pad of the integrated circuit chip and the light receiving element is shortened, the arrangement of the light receiving element is restricted by the position of the electrode pad in the integrated circuit chip. Therefore, in the above-described light receiving module, a wiring pattern for electrically connecting the light receiving element and the integrated circuit chip is provided on the first surface of the carrier. Thus, the distance between the electrode pad of the integrated circuit chip and the light receiving element can be increased, and the light receiving element can be freely disposed regardless of the position of the electrode pad.

  In the above light receiving module, the area of the first surface of the carrier may be half or more of the area of the third surface of the integrated circuit chip. As described above, since the ratio of the first surface of the carrier to the third surface of the integrated circuit chip is large, the degree of freedom in the arrangement of the light receiving elements can be further enhanced. Also, the ORL can be reduced by appropriately separating the light receiving element from the central axis of the incident light.

  In the light receiving module described above, the length of the wiring pattern in the direction connecting the first pad connected to the light receiving element and the second pad connected to the integrated circuit chip is one of the lengths of the first surface in the same direction. It may be 4 or more. As described above, since the ratio of the length of the wiring pattern to the length of the first surface of the carrier is large, the degree of freedom in the arrangement of the light receiving elements can be further enhanced. Also, the ORL can be reduced by appropriately separating the light receiving element from the central axis of the incident light.

  In the above-described light receiving module, the integrated circuit chip further includes another electrode pad on the third surface electrically connected to the lead pin provided on the stem, and the carrier is connected to the other electrode pad through the bonding wire. The first surface may further include another wiring pattern including a first bonding pad to be connected and a second bonding pad to be connected to the lead pin through a bonding wire. Thus, a wiring pattern for shortening other bonding wires may be further provided on the first surface of the carrier. Thereby, the wiring can be arranged more simply on the stem. Further, the inductance component can be reduced by shortening the length of the wire.

Details of the Embodiment of the Present Invention
Specific examples of the light receiving module according to the embodiment of the present invention will be described below with reference to the drawings. The present invention is not limited to these exemplifications, but is shown by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims. In the following description, the same reference numerals are given to the same elements in the description of the drawings, and the redundant description will be omitted.

  FIG. 1 is a cross-sectional view showing the configuration of a light receiving module 1A according to an embodiment of the present invention, showing a cross section along an optical axis of incident light. As shown in FIG. 1, the light receiving module 1 </ b> A of the present embodiment includes an optical receptacle 10 connected to an optical fiber, and a light receiving unit 20 fixed to the optical receptacle 10. The optical receptacle 10 also has a fiber stub (stub ferrule) 12, a metal member 14, a sleeve 16, and an outer shell member (shell) 18. The fiber stub 12 has a ferrule 11 and an optical fiber 13.

  The ferrule 11 is a member having a cylindrical shape (or a cylindrical shape). The central axis of the ferrule 11 extends along the direction A1, and the cross section perpendicular to the central axis of the ferrule 11 is circular. The ferrule 11 has a base end face 11a and a tip end face 11b aligned in the direction A1. The front end surface 11 b is a surface that makes physical contact with the ferrule of the optical connector connected to the optical receptacle 10, and is, for example, spherically polished. The base end surface 11 a is a surface on the opposite side to the tip end surface 11 b and faces the light receiving unit 20 attached to the optical receptacle 10. The base end face 11 a is slightly inclined (for example, about 8 °) with respect to a plane perpendicular to the central axis of the ferrule 11. The ferrule 11 further has an outer peripheral surface 11 c which is a cylindrical surface.

The ferrule 11 further has a fiber holding hole 11d. The fiber holding hole 11 d extends along the direction A 1 and is formed on the central axis of the ferrule 11. The cross section of the fiber holding hole 11 d is circular, and the inner diameter thereof is slightly larger than the outer diameter of the optical fiber 13. One opening of the fiber holding hole 11d is included in the tip end face 11b, and the other opening of the fiber holding hole 11d is included in the proximal end face 11a. That is, the fiber holding hole 11d penetrates between the base end face 11a and the tip end face 11b of the ferrule 11 along the direction A1. The ferrule 11 is made of, for example, zirconia (ZrO ₂ ). By forming the ferrule 11 with zirconia having high toughness and Young's modulus, physical contact can be suitably performed on the tip end face 11 b.

  The optical fiber 13 is, for example, a single mode fiber, and is a bare fiber from which a resin coating has been removed. The optical fiber 13 is made of, for example, quartz. The optical fiber 13 extends in the longitudinal direction (optical axis direction) in the direction A1 and has one end 13a and the other end 13b. The optical fiber 13 is inserted into the fiber holding hole 11d. Then, one end 13a is exposed from the opening of the fiber holding hole 11d on the tip end surface 11b side, and the other end 13b is exposed from the opening of the fiber holding hole 11d on the base end face 11a side. One end 13 a contacts one end of the optical fiber on the optical connector side connected to the optical receptacle 10. The other end 13 b is optically coupled to a photodiode 21 (described later) of the light receiving unit 20. The outer diameter of the optical fiber 13 is, for example, 125 μm.

  The metal member 14 has a through hole 14a extending in the direction A1, and is a member for holding the fiber stub 12 in the through hole 14a. The metal member 14 is made of, for example, a metal material such as stainless steel. The metal member 14 has a cylindrical shape extending along the direction A1. The metal member 14 has a base end surface 14 b and a tip end surface 14 c, and an outer peripheral surface 14 d. The base end face 14b and the tip end face 14c are aligned in the direction A1, and the through hole 14a penetrates between the base end face 14b and the tip end face 14c. The cross section of the through hole 14a perpendicular to the direction A1 is circular. The base end surface 14 b faces the package 22 (described later) of the light receiving unit 20. The fiber stub 12 is press-fit into the through hole 14a of the metal member 14 along the direction A1. That is, the outer peripheral surface 11 c of the ferrule 11 is in contact with the inner surface of the through hole 14 a, whereby the fiber stub 12 is fixed to the metal member 14.

  The sleeve 16 is a cylindrical member extending along the direction A1, and is made of, for example, ceramic. In one example, the sleeve 16 is made of the same material as the ferrule 11 (e.g., zirconia). The inner diameter of the sleeve 16 is approximately equal to the outer diameter of the fiber stub 12. The sleeve 16 has a proximal end 16a and a distal end 16b aligned in the direction A1. The sleeve 16 also has an outer circumferential surface 16 c and an inner circumferential surface 16 d. The fiber stub 12 is inserted from the opening on the proximal end 16 a side of the sleeve 16. In other words, a part of the proximal end 16 a side of the sleeve 16 is inserted into the gap between the outer peripheral surface 11 c of the ferrule 11 and the metal member 14. Accordingly, the outer peripheral surface 16 c of the sleeve 16 is in contact with the metal member 14, and the inner peripheral surface 16 d of the sleeve 16 is in contact with the outer peripheral surface 11 c of the ferrule 11. The optical connector ferrule is inserted from the opening on the tip 16 b side of the sleeve 16. The tip end face 11 b of the ferrule 11 and the tip end face of the optical connector ferrule contact each other in the sleeve 16. Thus, the optical fiber 13 held by the ferrule 11 and the optical fiber held by the optical connector ferrule are optically coupled to each other with high coupling efficiency.

  The outer shell member 18 is a member fixed to the metal member 14 and connected to the optical connector. The outer shell member 18 is a cylindrical member extending along the direction A1, and is made of metal such as stainless steel. The outer shell member 18 has a flange portion 18a and a through hole 18d extending along the direction A1. Further, the outer shell member 18 has a base end face 18 b and a tip end 18 c aligned in the direction A1. The flange portion 18 a is a disk-shaped portion that protrudes toward the outside of the outer shell member 18. The flange portion 18a is provided on the proximal end surface 18b side of the outer shell member 18, and in the present embodiment, one surface of the flange portion 18a constitutes the proximal end surface 18b. The through hole 18 d penetrates between the proximal end surface 18 b and the distal end portion 18 c. The cross section of the through hole 18d perpendicular to the direction A1 is circular, and its central axis coincides with the central axis of the fiber stub 12 and the metal member 14. The outer shell member 18 includes, as a part of the through hole 18d, a first portion 18e on the proximal end surface 18b side and a second portion 18f on the distal end portion 18c side. The first portion 18e extends from the proximal end face 18b along the direction A1 to the second portion 18f. The second portion 18f extends from the tip portion 18c along the direction A1 to the first portion 18e. The first portion 18 e and the second portion 18 f are connected (communicated) with each other between the tip 16 b and the tip 18 c of the sleeve 16. The inner diameter of the first portion 18 e is approximately equal to or slightly larger than the outer diameter of the outer circumferential surface 16 c of the sleeve 16. The inner diameter of the second portion 18 f is slightly larger than the inner diameter of the inner circumferential surface 16 d of the sleeve 16. As described above, since the inner diameter of the first portion 18e is larger than the inner diameter of the second portion 18f, the step surface 18g is formed between the first portion 18e and the second portion 18f. The step surface 18 g faces the tip 16 b of the sleeve 16.

  The light receiving unit 20 includes a photodiode 21 (light receiving element), a package 22, a lens 23, a stem 24, a carrier 25, an integrated circuit chip 26, and a plurality of lead pins 27.

  The stem 24 is a substantially circular flat insulating member and has a flat major surface 24 a. The major surface 24 a intersects the optical axis of the optical fiber connected to the optical receptacle 10 (that is, the optical axis of the optical fiber 13). In one example, the major surface 24 a is perpendicular to the optical axis of the optical fiber connected to the optical receptacle 10 (the optical axis of the optical fiber 13). The stem 24 is made of, for example, a material such as ceramic.

  The package 22 is a substantially cylindrical metal member, and its central axis is along the optical axis of the optical fiber 13. The proximal end 22 a of the package 22 in the optical axis direction of the optical fiber 13 is fixed to the main surface 24 a of the stem 24 via an annular member 29. Specifically, the annular member 29 has one end surface 29a and the other end surface 29b in the optical axis direction. One end 22 a on the proximal end side of the package 22 is fixed to one end face 29 a of the member 29, and the main surface 24 a of the stem 24 is fixed to the other end face 29 b of the member 29. Further, one end 22 b on the tip end side of the package 22 in the optical axis direction of the optical fiber 13 is fixed to the metal member 14 via the cylindrical member 19. Specifically, the metal member 14 is inserted from one end of the tip end side of the member 19 and the outer peripheral surface of the metal member 14 and the inner peripheral surface of the member 19 are fixed to each other. Further, one end 22 b on the distal end side of the package 22 is fixed to the surface on the proximal end side of the member 19. The package 22 is made of, for example, a material such as an iron-nickel alloy.

  The plurality of lead pins 27 are bar-like metal members extending in a direction intersecting the main surface 24 a of the stem 24. A plurality of lead pins 27 are provided through the stem 24 and fixed to the stem 24. The plurality of lead pins 27 transmit and receive electric signals and power to the photodiodes 21 and the integrated circuit chip 26 disposed in the space defined by the package 22 and the stem 24.

  The lens 23 is held inside the package 22 and is fixed to the inner peripheral surface of the package 22 via the resin 23 a. The lens 23 is a condensing lens made of a light transmitting member, and is disposed on the optical axis of the optical fiber 13. The lens 23 condenses the light emitted from the other end 13 b of the optical fiber 13 toward the vicinity of the photodiode 21. In order to prevent return light from the photodiode 21, the optical axis of the lens 23 is slightly offset with respect to the optical axis of the optical fiber 13.

  The photodiode 21 is optically coupled to the other end 13 b of the optical fiber 13 via the lens 23, receives light from the optical fiber connected to the optical receptacle 10, and has a size according to the intensity of the light Output a current signal of The photodiode 21 is mounted on the insulating carrier 25, and the carrier 25 is disposed on the integrated circuit chip 26. That is, the photodiode 21 is mounted on the integrated circuit chip 26 via the carrier 25. The integrated circuit chip 26 is a semiconductor IC that receives a current signal from the photodiode 21 and converts the current signal into a voltage signal.

  Here, FIG. 2 is an enlarged side view showing a configuration in the vicinity of the photodiode 21 of the light receiving unit 20. As shown in FIG. As shown in FIG. 2, the integrated circuit chip 26 has a third surface 26 b and a fourth surface 26 a opposite to the third surface 26 b. The fourth surface 26 a and the third surface 26 b are aligned in the optical axis direction of the optical fiber 13 and extend along a plane intersecting (eg, orthogonal to) the optical axis direction. The integrated circuit chip 26 faces the main surface 24 a of the stem 24 at the fourth surface 26 a. The carrier 25 has a first surface 25 b and a second surface 25 a opposite to the first surface 25 b. The carrier 25 faces the third surface 26 b of the integrated circuit chip 26 at the second surface 25 a. The photodiode 21 has the main surface 21 a and the opposite surface 21 b opposite to the main surface 21 a, and receives light from the main surface 21 a. The carrier 25 mounts the photodiode 21 on the first surface 25 b such that the first surface 25 b and the opposite surface 21 b of the photodiode 21 face each other.

  FIG. 3 is a plan view of the light receiving unit 20 from which the package 22 and the lens 23 are removed. FIG. 4 is a plan view of the third surface 26 b of the integrated circuit chip 26. FIG. 5 is a plan view of the first surface 25 b of the carrier 25. As shown in FIG. 3, a GND pattern 24 b defined at a reference potential (ground potential) is provided on the main surface 24 a of the stem 24. Further, a plurality of lead pins 27 a to 27 f are provided at the peripheral edge of the stem 24.

  As shown in FIG. 4, the third surface 26b of the integrated circuit chip 26 is a rectangle having a pair of sides 26c, 26d extending along the short direction and a pair of sides 26e, 26f extending along the longitudinal direction. It has a shape. The integrated circuit chip 26 has a plurality of electrode pads 28 on the third surface 26 b. Of the electrode pads 28, the three electrode pads 28 a to 28 c aligned along the side 26 c of the third surface 26 b are electrically connected to the photodiodes 21. Specifically, the two electrode pads 28 a and 28 c are connected to the cathode electrode of the photodiode 21 and apply a bias voltage to the photodiode 21. The electrode pad 28 b is connected to the anode electrode of the photodiode 21, and receives the current signal output from the photodiode 21.

  Further, the electrode pad 28d positioned closer to the side 26e of the third surface 26b inputs a bias voltage to the photodiode 21 from the outside of the light receiving module 1A. As shown in FIG. 3, the electrode pad 28d is electrically connected to one electrode of the capacitor (chip capacitor) 41 mounted on the GND pattern 24b via a bonding wire. The one electrode of the capacitor 41 is electrically connected to the lead pin 27d through a bonding wire. The other electrode of the capacitor 41 is electrically connected to the GND pattern 24 b via a conductive adhesive (for example, solder or the like). The via hole 51 is a via hole connecting the GND pattern 24 b and the stem body.

  The electrode pads 28e and 28f arranged along the side 26f of the third surface 26b input the power supply voltage to the integrated circuit chip 26 from the outside of the light receiving module 1A. As shown in FIG. 3, the electrode pads 28e and 28f are electrically connected to one electrode of a capacitor (chip capacitor) 42 mounted on the GND pattern 24b via a bonding wire. The one electrode of the capacitor 42 is electrically connected to the lead pin 27a via a bonding wire. The other electrode of the capacitor 42 is electrically connected to the GND pattern 24 b via a conductive adhesive.

  The electrode pads 28g and 28h arranged along the side 26d of the third surface 26b output the voltage signal generated based on the current signal from the photodiode 21 to the outside of the light receiving module 1A. As shown in FIG. 3, one electrode pad 28g is electrically connected to the lead pin 27e through a bonding wire. The other electrode pad 28 h is electrically connected to another lead pin 27 f via a bonding wire.

  The plurality of electrode pads 28 include a plurality of electrode pads 28i to 28n that define the reference potential (ground potential) of the integrated circuit chip 26. The electrode pads 28i to 28n are electrically connected to the GND pattern 24b via bonding wires and the conductive GND block 43 (see FIG. 3). The other electrode pads 28 include an electrode pad for current monitoring, an electrode pad for gain adjustment, and the like.

  As shown in FIG. 5, the first surface 25b of the carrier 25 has a rectangular shape having a pair of sides 25c, 25d extending along the short direction and a pair of sides 25e, 25f extending along the longitudinal direction. It is presenting. As shown in FIG. 3, the longitudinal direction of the carrier 25 coincides with the longitudinal direction of the integrated circuit chip 26. The area of the first surface 25 b of the carrier 25 is half or more of the area of the third surface 26 b of the integrated circuit chip 26. The square frame D1 shown in FIG. 5 indicates the mounting area of the photodiode 21.

  The carrier 25 has wiring patterns 31 to 33 electrically connected to the photodiode 21 on the first surface 25 b. The wiring patterns 31 to 33 extend along the longitudinal direction of the first surface 25 b and are arranged in this order in the short direction. The wiring patterns 31 to 33 include pads 31 b to 33 b (first pads) at one end in their extending direction. The pad 32 b of the wiring pattern 32 is provided on one electrode pad provided on the opposite surface 21 b of the photodiode 21, and the pads 31 b and 33 b of the wiring patterns 31 and 33 are provided on the other surface 21 b of the photodiode 21. Each of the electrode pads is electrically connected via a conductive adhesive. In addition, the wiring patterns 31 to 33 include bonding pads 31 a to 33 a (second pads) at the other end in the extending direction. The bonding pads 31a to 33a are arranged along the side 25c of the first surface 25b. The distance between the bonding pads 31a to 33a is, for example, 50 μm. As shown in FIG. 3, the bonding pads 31a to 33a are respectively connected to the electrode pads 28a to 28c via individual bonding wires. Thus, the wiring patterns 31 to 33 electrically connect the electrode pad 28 b to one electrode of the photodiode 21 and electrically connect the electrode pads 28 a and 28 c to the other electrode of the photodiode 21.

  A wiring pattern 34 is further provided on the first surface 25 b of the carrier 25. The wiring pattern 34 is disposed between the wiring patterns 31 to 33 and the side 25 d. The wiring pattern 34 is electrically connected to the wiring patterns 31 and 33 via the flow prevention region 35 of the conductive adhesive. A part of the flow stop area 35 overlaps the photodiode 21. A capacitor (chip capacitor) is mounted on the wiring pattern 34. In addition, the square frame D2 shown by FIG. 5 has shown the mounting area | region of the capacitor. One electrode of the capacitor is electrically connected to the wiring pattern 34, and the other electrode is electrically connected to one of the electrode pads 28g to 28k of the integrated circuit chip 26 through a bonding wire.

  Here, in FIG. 3 and FIG. 5, the central axis AX of incident light is shown. The central axis AX is slightly offset with respect to the central axes of the package 22 and the stem 24. And in this embodiment, electrode pad 28a-28c and bonding pad 31a-33a are arrange | positioned on the opposite side to the center O of the photodiode 21 on both sides of central axis AX. In other words, the central axis AX is located between the electrode pads 28 a to 28 c and the bonding pads 31 a to 33 a and the center O of the photodiode 21. Therefore, the center O of the photodiode 21 does not coincide with the central axis AX, and is off the central axis AX. The distance W1 between the center O of the light receiving surface of the photodiode 21 and the central axis AX in the longitudinal direction of the first surface 25b is, for example, 200 μm. The length L1 of the wiring patterns 31 to 33 in the direction connecting the bonding pads 31b to 33b and the bonding pads 31a to 33a (that is, the longitudinal direction of the first surface 25b) is 1 of the length L2 of the first surface 25b in the same direction. It is / 4 or more, more preferably 1/2 or more.

  The effects obtained by the light receiving module 1A according to the present embodiment described above will be described together with the problems of the comparative example. FIGS. 10 and 11 are plan views showing the configuration on the stem 24 of the light receiving modules 100 and 200 according to the comparative example. In these examples, the carrier 125 carrying the photodiode 21 is arranged side by side with the integrated circuit chip 26 not on the integrated circuit chip 26 but on the GND pattern 24 b. Although the carrier 125 has the wiring patterns 131 to 133 electrically connected to the photodiodes 21 on the mounting surface, these lengths are shorter than the wiring patterns 31 to 33 in the present embodiment.

  When the ratio of the area of the integrated circuit chip 26 to the area of the main surface 24 a of the stem 24 is sufficiently small as in the light receiving module 100 shown in FIG. 10, the photodiode 21 is made near the central axis of incident light. In addition to the arrangement, the carrier 125 can be arranged in the vicinity of the electrode pads 28 a to 28 c of the integrated circuit chip 26 to shorten the bonding wire connecting them. However, as in the light receiving module 200 shown in FIG. 11, when the ratio of the area of the integrated circuit chip 26 to the area of the main surface 24 a of the stem 24 becomes large due to the functionalization of the integrated circuit chip 26 or the like, It can not be disposed in the vicinity of the pads 28a to 28c, and the bonding wires connecting them become long. As the bonding wire becomes longer, the signal waveform is degraded. In addition, the position of the photodiode 21 largely deviates from the central axis of the incident light, and the light reception sensitivity is lowered.

  Therefore, in the light receiving module 1A of the present embodiment, the second surface 25a of the carrier 25 on which the photodiode 21 is mounted and the third surface 26b of the integrated circuit chip 26 are opposed to each other. That is, the carrier 25 carrying the photodiode 21 is mounted on the integrated circuit chip 26. As a result, even when the integrated circuit chip 26 has a large size, the degree of freedom of the arrangement of the photodiodes 21 can be increased, so that the photodiodes 21 can be arranged near the central axis of the incident light. A decrease in light receiving sensitivity can be suppressed.

  However, simply arranging the carriers 125 of the light receiving modules 100 and 200 shown in FIGS. 10 and 11 on the integrated circuit chip 26 causes the following problem. That is, when the distance between the electrode pads 28a to 28c of the integrated circuit chip 26 and the photodiode 21 increases, the bonding wires connecting the electrode pads 28a to 28c and the carrier 125 become longer, which leads to deterioration of the waveform of the electric signal. In addition, if the distance between the electrode pads 28a to 28c of the integrated circuit chip 26 and the photodiode 21 is shortened, the arrangement of the carrier 125 is restricted by the positions of the electrode pads 28a to 28c. Therefore, in the light receiving module 1A of the present embodiment, the wiring patterns 31 to 33 extending long are provided on the first surface 25b of the carrier 25. As a result, the distance between the electrode pads 28 a to 28 c of the integrated circuit chip 26 and the photodiode 21 can be increased, and the photodiode 21 can be freely disposed regardless of the positions of the electrode pads 28 a to 28 c. Further, in the light receiving module 1A, the electrode pads 28a to 28c and the bonding pads 31a to 33a are disposed on the opposite side of the center O of the photodiode 21 with respect to the central axis AX of incident light. Accordingly, even when the ratio of the integrated circuit chip 26 to the main surface 24 a of the stem 24 is large, the photodiode 21 can be appropriately separated from the central axis AX of the incident light to reduce the ORL.

  Further, as in the present embodiment, the area of the first surface 25 b of the carrier 25 may be half or more of the area of the third surface 26 b of the integrated circuit chip 26. As described above, since the ratio of the first surface 25b of the carrier 25 to the third surface 26b of the integrated circuit chip 26 is large, the degree of freedom in the arrangement of the photodiodes 21 can be further enhanced. Also, the ORL can be reduced by appropriately separating the photodiode 21 from the central axis AX of the incident light.

  Further, as in the present embodiment, the lengths of the wiring patterns 31 to 33 in the direction connecting the bonding pads 31b to 33b and the bonding pads 31a to 33a are at least 1/4 of the length of the first surface 25b in the same direction. It may be As described above, when the ratio of the lengths of the wiring patterns 31 to 33 in the length of the first surface 25 b of the carrier 25 is large, the degree of freedom in the arrangement of the photodiodes 21 can be further enhanced. Also, the ORL can be reduced by appropriately separating the photodiode 21 from the central axis AX of the incident light.

(First modification)
FIG. 6 is a plan view showing a carrier 25A according to a first modification of the embodiment. The difference between the carrier 25A of this modification and the carrier 25 of the above embodiment is the shape of the wiring pattern. That is, the carrier 25A of this modification has the same wiring patterns 31, 32 and 34 as the above embodiment but does not have the wiring pattern 33. Therefore, one electrode of the photodiode 21 is electrically connected to the integrated circuit chip 26 only through the wiring pattern 31 and the bonding wire connected to the wiring pattern 31. Even when the light receiving module 1A of the above embodiment includes the carrier 25A shown in FIG. 6 instead of the carrier 25 shown in FIG. 5, the effects of the above embodiment can be obtained. Further, the distance between the bonding pad 31a and the bonding pad 32a can be made wider than in the above embodiment.

(2nd modification)
FIG. 7 is a plan view showing a carrier 25B according to a second modification of the embodiment. Moreover, FIG. 8 is a top view which shows the structure on the stem 24 in this modification. The difference between the carrier 25B of this modification and the carrier 25 of the above embodiment is the shape of the wiring pattern. That is, as shown in FIG. 7, the carrier 25B of this modification further includes the wiring pattern 36 on the first surface 25b in addition to the wiring patterns 31, 32 and 34 similar to the above embodiment. The wiring pattern 36 extends along the longitudinal direction of the first surface 25 b (along the side 25 e of the first surface 25 b). The wiring patterns 31, 32 and 36 are arranged in this order in the short direction.

  The wiring pattern 36 includes a bonding pad 36 a (first bonding pad) at one end in the extending direction. The bonding pad 36 a is disposed at a position near the side 25 e of the first surface 25 b and adjacent to the wiring pattern 34. As shown in FIG. 8, the bonding pad 36 a is connected to one other control electrode pad 28 except the electrode pads 28 a to 28 k of the integrated circuit chip 26 via a bonding wire.

  The wiring pattern 36 also includes a bonding pad 36 b (second bonding pad) at the other end in the extending direction. The bonding pads 31a, 32a and 36b are arranged along the side 25c of the first surface 25b. As shown in FIG. 8, the bonding pad 36b is connected to one lead pin 27c via a bonding wire. Thus, the control electrode pad 28 of the integrated circuit chip 26 and the lead pin 27 c are electrically connected.

  Even when the light receiving module 1A of the above embodiment includes the carrier 25B shown in FIG. 7 instead of the carrier 25 shown in FIG. 5, the effects of the above embodiment can be obtained. Further, as in the present modification, by providing the wiring pattern 36 on the first surface 25 b of the carrier 25 B, the other electrode pads 28 except the electrode pads 28 a to 28 k of the integrated circuit chip 26 and the lead pins 27 c are electrically The bonding wire connecting to can be shortened. FIG. 9 is a plan view showing the case where the electrode pad 28 and the lead pin 27 c are connected via the bonding wire 61 and the plurality of capacitors 62 as a comparative example. According to this modification, the wiring can be arranged more simply on the stem 24 as compared with the configuration shown in FIG. In addition, the bonding wire can be shortened, the inductance component can be reduced, and the electrical characteristics of the light receiving module 1A can be further enhanced.

  The light receiving module according to the present invention is not limited to the embodiment described above, and various other modifications are possible. For example, the above-mentioned embodiment and each modification may be combined with each other according to the required purpose and effect. For example, the carrier may have the wiring pattern 36 of the second modification in addition to the wiring patterns 31 to 33 of the above embodiment. Moreover, although the case where a capacitor is provided on the carrier in addition to the photodiode is illustrated in the above embodiment, only the photodiode may be provided on the carrier.

  DESCRIPTION OF SYMBOLS 1A ... Light reception module, 10 ... Optical receptacle, 11 ... Ferrule, 11a ... Base end surface, 11b ... Tip surface, 11c ... Outer peripheral surface, 11d ... Fiber holding hole, 12 ... Fiber stub, 13 ... Optical fiber, 13a ... One end, 13b ... Other end, 14 ... Metal member, 14a ... Through hole, 14b ... Base end face, 14c ... Tip surface, 14d ... Outer peripheral surface, 16 ... Sleeve, 16a ... Base end, 16b ... Tip, 16c ... Outer peripheral surface, 16d ... Inside Peripheral surface, 18 Outer shell member 18a Flange portion 18b Base end face 18c Tip portion 18d Through hole 18e First portion 18f Second portion 18g Step surface 19 19 member 20: light receiving portion 21: photodiode (light receiving element) 21a: main surface 21b: opposite surface 22: package 23: lens 23: resin 24: stem 24: 24a main surface 2 b GND pattern 25 25 A 25 B carrier 25 a second surface 25 b first surface 25 c to 25 f side 26 integrated circuit chip 26 a fourth surface 26 b third surface 26 c 26f: Side, 27a to 27f: Lead pin, 28, 28a to 28n: Electrode pad, 29: Member, 31 to 34, 36: Wiring pattern, 31a to 33a, 36a, 36b: Bonding pad, 31b to 33b: Pad, 35: Stop flow region 41, 42: capacitor 43: GND block 61: bonding wire 62: capacitor AX: central axis of incident light

Claims (5)

A light receiving element having a main surface and an opposite surface opposite to the main surface and receiving light from the main surface;
A carrier having a first surface and a second surface opposite to the first surface, the carrier mounting the light receiving element on the first surface;
An integrated circuit chip having a third surface and a fourth surface opposite to the third surface, the carrier being mounted on the third surface;
A stem mounting the integrated circuit chip on the main surface;
A wiring pattern provided on the first surface of the carrier, having first and second pads disposed at both ends, and connecting the light receiving element and the integrated circuit chip;
, A light receiving module.   The light receiving module according to claim 1, wherein an area of the first surface of the carrier is half or more of an area of the third surface of the integrated circuit chip. The light receiving element has an electrode pad on the opposite surface,
The light receiving module according to claim 1, wherein the electrode pad is connected to the first pad of the wiring pattern provided on the first surface of the carrier.   The length of the wiring pattern in the direction connecting the first pad connected to the light receiving element and the second pad connected to the integrated circuit chip is one of the lengths of the first surface in the same direction. The light receiving module according to any one of claims 1 to 3, which is 4/4 or more. The integrated circuit chip further includes another electrode pad on the third surface electrically connected to a lead pin provided on the stem,
The carrier further includes another wiring pattern including a first bonding pad connected to the other electrode pad via a bonding wire, and a second bonding pad connected to the lead pin via a bonding wire. The light receiving module according to any one of claims 1 to 4, further comprising one surface.

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