Optical module

Abstract

The utility model provides an optical module. The optical module includes: a circuit board; the optical detector is used for converting an optical signal into an electric signal; the transimpedance amplifier is provided with a chip mounting area for flip-chip bonding of the optical detector and a first signal bonding pad electrically connected with the circuit board; the optical detector is arranged in the chip installation area, the chip installation area comprises a second signal bonding pad electrically connected with the first signal bonding pad, and the second signal bonding pad is electrically connected with a signal electrode of the optical detector. And the second signal bonding pad is positioned on one side, which is adjacent to the first signal bonding pad, of the chip mounting area. The high-speed link of the optical module provided by the utility model has small inductance and impedance, thereby facilitating the improvement of bandwidth and link rate.

Description

Technical Field

[0001] The utility model relates to the technical field of optical communication, in particular to an optical module. Background Art

[0002] With the rapid development of optical communication and Internet in recent years, users' demand for network has also increased sharply, which has led to the rapid growth of traffic in telecommunication backbone network at a rate of 50% to 80% per year. In order to adapt to the trend of rapid development of network market, the transmission speed of optical modules is also increasing rapidly, from traditional single-channel 25G optical modules to 100G optical modules, and even single-channel 200G or higher optical modules.

[0003] For an optical module with a light receiving function, it usually includes a circuit board, a transimpedance amplifier, and a photodetector. The optical signal received by the optical module is converted into an electrical signal by the photodetector, and the electrical signal is then transmitted to the circuit board via the transimpedance amplifier. In the process of transmitting the electrical signal from the photodetector to the circuit board via the transimpedance amplifier, the inductance will cause the impedance to increase, which will have an important impact on the bandwidth and limit the link rate. Utility Model Content

[0004] The purpose of the utility model is to provide an optical module, so as to reduce the inductance in the link to a certain extent, thereby improving the link rate.

[0005] To achieve the above object, an embodiment provides an optical module. The optical module includes:

[0006] Circuit boards;

[0007] A photodetector for converting an optical signal into an electrical signal; and

[0008] A transimpedance amplifier having a chip mounting area for flip-chip bonding of the photodetector and a first signal pad electrically connected to the circuit board;

[0009] The photodetector is arranged in the chip mounting area, and the chip mounting area includes a second signal pad electrically connected to the first signal pad, the second signal pad is electrically connected to the signal electrode of the photodetector, and the second signal pad is located on a side of the chip mounting area adjacent to the first signal pad.

[0010] As a further improvement of an implementation mode, the transimpedance amplifier includes a front edge and a rear edge that are relatively arranged, the first signal pad is relatively close to the rear edge, and the chip mounting area is relatively close to the front edge;

[0011] The second signal pad is located at a rear side of the chip mounting area.

[0012] As a further improvement of an embodiment, the transimpedance amplifier further comprises a signal transmission circuit, and the signal transmission circuit comprises an amplification circuit for amplifying the electrical signal of the transimpedance amplifier;

[0013] The signal transmission line is electrically connected between the second signal pad and the first signal pad, and is arranged between the second signal pad and the first signal pad in a front-to-rear direction.

[0014] As a further improvement of an embodiment, in the front-to-back direction, the signal transmission line extends from the second signal pad gradually toward the first signal pad.

[0015] As a further improvement of an implementation manner, the signal transmission circuit includes:

[0016] A first surface circuit, formed with the first signal pad;

[0017] A second surface layer circuit is formed with the second signal pad; and

[0018] The inner layer circuit is located inside the transimpedance amplifier, the inner layer circuit includes the amplifier circuit, and two ends of the inner layer circuit are electrically connected to the second signal pad and the first signal pad through conductive holes.

[0019] As a further improvement of an implementation mode, the chip mounting area further includes:

[0020] a support pad, the support pad being located at a front side of the chip mounting area; and / or,

[0021] a power pad, the power pad being located at the rear side of the chip mounting area and arranged side by side with the second signal pad;

[0022] The light detector further comprises:

[0023] a mechanical support pad flip-chip fixed to the support pad; and / or,

[0024] A power electrode is electrically connected to the power pad by flip-chip bonding.

[0025] As a further improvement of an embodiment, the number of the chip mounting areas is more than two, and the more than two chip mounting areas are distributed side by side along a second direction perpendicular to the front-rear direction;

[0026] The transimpedance amplifier further includes a second ground pad located between two adjacent chip mounting areas or located on both sides of any chip mounting area in the second direction, and the second ground pad is electrically connected to the circuit board.

[0027] As a further improvement of an implementation manner, the first signal pad is electrically connected to the signal line of the circuit board through welding, conductive glue or bonding wires.

[0028] As a further improvement of an implementation manner, the optical module further comprises a conductive silver glue layer, and the transimpedance amplifier is adhered to the ground pattern layer on the surface of the circuit board through the conductive silver glue layer.

[0029] As a further improvement of an implementation manner, the first signal pad is electrically connected to the signal line of the circuit board through four bonding wires;

[0030] In the thickness direction of the circuit board, heights of two of the four bonding wires are greater than heights of the other two.

[0031] As a further improvement of an implementation manner, the first signal pad is electrically connected to the signal line of the circuit board through two bonding wires;

[0032] The distance between two solder joints of the two bonding wires at the first signal pad is smaller than the distance between two solder joints at the signal line.

[0033] As a further improvement of an implementation mode, the transimpedance amplifier includes a pad group;

[0034] The pad group includes the first signal pad and at least two first ground pads, and is arranged in a GSG structure, a GSSG structure or a GSGSG structure, wherein the two first ground pads on both sides of the pad group are electrically connected through bonding wires.

[0035] As a further improvement of an implementation manner, the transimpedance amplifier is disposed on the circuit board, or the transimpedance amplifier and the circuit board are arranged side by side.

[0036] As a further improvement of an implementation manner, the transimpedance amplifier is fixedly mounted on the surface of the circuit board;

[0037] The first signal pad is electrically connected to the signal line of the circuit board through a bonding wire, and in the thickness direction of the circuit board, the difference between the height of the bonding wire from the circuit board and the height of the first signal pad from the circuit board is less than 100 μm.

[0038] As a further improvement of an implementation manner, the optical module further includes an optical mirror and a support block, wherein the support block is fixed on the transimpedance amplifier, and the optical mirror is fixed on the support block and extends to the light incident path of the photodetector.

[0039] Compared with the prior art, the beneficial effect of one embodiment of the utility model is that the first signal pad of the transimpedance amplifier is electrically connected to the circuit board, the optical detector is electrically connected to the second signal pad of the chip mounting area of ​​the transimpedance amplifier through flip-chip welding, and the second signal pad is arranged on a side of the chip mounting area close to the first signal pad, so that the transmission position of the electrical signal from the optical detector to the transimpedance amplifier is close to the first signal pad, and further, the high-speed link of the optical module has a smaller inductance, which reduces the impedance, thereby facilitating the improvement of bandwidth and link rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic diagram of the three-dimensional structure of an optical module in one embodiment of the utility model;

[0041] Figure 2 It is a three-dimensional schematic diagram of a partial structure of an optical module in one embodiment of the utility model;

[0042] Figure 3 It is a projection schematic diagram of a transimpedance amplifier in an embodiment of the utility model;

[0043] Figure 4 is a schematic projection diagram of a first side surface of a light detector in one embodiment of the utility model;

[0044] Figure 5 It is a partial side view schematic diagram of a light detector, a transimpedance amplifier and a circuit board in one embodiment of the utility model;

[0045] Figure 6 It is a schematic diagram of the three-dimensional structure of a light detector, a transimpedance amplifier and a partial circuit board in one embodiment of the utility model;

[0046] Figure 7 It is a projection schematic diagram of a partial structure of an optical module in one embodiment of the utility model;

[0047] Figure 8 is a three-dimensional schematic diagram of a partial structure of an optical module in one embodiment of the utility model from one viewing angle;

[0048] Fig. 9 is a three-dimensional schematic diagram of a partial structure of an optical module in one embodiment of the utility model from another viewing angle;

[0049] Fig.10 It is a schematic diagram of the three-dimensional structure of a light detector, a transimpedance amplifier and a partial circuit board in another embodiment of the utility model;

[0050] Fig.11 It is a projection diagram of a partial structure of an optical module in another embodiment of the utility model. DETAILED DESCRIPTION

[0051] The present application will be described in detail below in conjunction with the specific implementations shown in the accompanying drawings. However, these implementations do not limit the present application, and any structural, methodological, or functional changes made by a person of ordinary skill in the art based on these implementations are all included in the protection scope of the present application.

[0052] In various drawings of the present application, for the convenience of illustration, some sizes of structures or parts are exaggerated relative to other structures or parts, and thus, are only used to illustrate the basic structure of the subject matter of the present application.

[0053] As used herein, terms indicating spatial relative positions such as "upper," "above," "lower," and "below" are used for the purpose of convenience to describe the relationship of one unit or feature relative to another unit or feature as shown in the accompanying drawings. Terms of spatial relative position may be intended to include different orientations of the device in use or operation in addition to the orientation shown in the drawings. For example, if the device in the figure is turned over, units described as being "below" or "beneath" other units or features will be located "above" the other units or features. Thus, the exemplary term "below" can encompass both above and below orientations. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatially relative descriptors used herein interpreted accordingly.

[0054] Example 1

[0055] Ginseng Figure 1 , this embodiment provides an optical module 100.

[0056] The optical module 100 at least has a light receiving function; one end of the optical module 100 has an optical interface, and the other end has an electrical interface 100A.

[0057] The optical module 100 is optically connected to an external mechanism through the optical interface, and allows an external optical signal to enter the optical module 100 via the optical interface to achieve a light receiving function.

[0058] The optical module 100 is electrically connected to another external mechanism through the electrical interface 100A, and the electrical signal in the optical module 100 is outputted externally through the electrical interface 100A. For example, a portion of the circuit board 10 described below is electrically connected to the other external mechanism at the electrical interface 100A.

[0059] Specifically, refer to Figure 2 The optical module 100 includes a housing 90 , and includes a light detector 30 , a transimpedance amplifier 20 and a circuit board 10 accommodated in the housing 90 .

[0060] The optical detector 30 is used to convert the optical signal of the optical module 100 into an electrical signal.

[0061] The photodetector 30 is electrically connected to the transimpedance amplifier 20 , and at the same time, the transimpedance amplifier 20 is electrically connected to the circuit board 10 , whereby the electrical signal is transmitted from the photodetector 30 to the transimpedance amplifier 20 , and then to the circuit board 10 , thereby forming a high-speed link from the photodetector 30 to the circuit board 10 via the transimpedance amplifier 20 .

[0062] Specifically, combined Figure 3 and Figure 4 The transimpedance amplifier 20 has a first signal pad 21S, and the first signal pad 21S is electrically connected to the circuit board 10 , that is, the electrical signal of the transimpedance amplifier 20 leaves the transimpedance amplifier 20 via the first signal pad 21S and is transmitted to the circuit board 10 .

[0063] The transimpedance amplifier 20 further has a chip mounting area D, and the photodetector 30 is disposed in the chip mounting area D.

[0064] The chip mounting area D includes a second signal pad 22S electrically connected to the first signal pad 21S. The photodetector 30 is disposed in the chip mounting area D of the transimpedance amplifier 20 by flip-chip bonding, and the signal electrode 31S of the photodetector 30 is electrically connected to the second signal pad 22S.

[0065] The second signal pad 22S is located at one side of the chip mounting area D adjacent to the first signal pad 21S.

[0066] That is to say, in the chip mounting area D, the second signal pad 22S is closer to the first signal pad 21S than other pads, or at least not far from the first signal pad 21S relative to other pads (i.e., the distance between the second signal pad 22S and the first signal pad 21S is smaller or substantially equal to that between the second signal pad 22S and the first signal pad 21S). Here, the other pads are, for example, the support pad 23 and the power pad 26 described later. In the chip mounting area D, the second signal pad 22S is closer to the first signal pad 21S relative to the support pad 23, and the distance between the second signal pad 22S and the first signal pad 21S relative to the power pad 26 is substantially the same.

[0067] In this way, the transmission position of the electrical signal from the optical detector 30 to the transimpedance amplifier 20 (i.e., the location of the second signal pad 22S) is close to the first signal pad 21S. As a result, the high-speed link of the optical module 100 has a smaller inductance and reduces the impedance, thereby facilitating the improvement of bandwidth and link rate.

[0068] In one embodiment, Figure 3 The transimpedance amplifier 20 has a first edge 201 and a second edge 202 that are arranged opposite to each other in a first direction, the first signal pad 21S is relatively close to the second edge 202 , and the chip mounting area D is relatively close to the first edge 201 .

[0069] For ease of understanding and description, the front-to-back direction is defined by the first direction. From another perspective, the front-to-back direction is defined by the relative positions of the first signal pad 21S and the chip mounting area D; wherein, the first edge 201 close to the chip mounting area D defines the direction "front", and the second edge 202 close to the first signal pad 21S defines the direction "back".

[0070] Therefore, the first edge 201 may also be referred to as a front edge 201 , and the second edge 202 may also be referred to as a rear edge 202 .

[0071] Furthermore, in one embodiment, the aforementioned “second signal pad 22S is located on a side of the chip mounting area D adjacent to the first signal pad 21S” means that the second signal pad 22S is located on the rear side of the chip mounting area D.

[0072] Furthermore, in one embodiment, the optical interface and the electrical interface 100A are also arranged relatively along the first direction, that is, arranged relatively in the front-to-back direction. For example, the optical interface is located at the front end of the optical module 100 and the electrical interface 100A is located at the rear end of the optical module 100.

[0073] Correspondingly, the first signal pad 21S is located on a side of the transimpedance amplifier 20 relatively close to the electrical interface 100A, and the chip mounting area D is located on a side of the transimpedance amplifier 20 relatively close to the optical interface; and the second signal pad 22S is located on a side of the chip mounting area D relatively close to the electrical interface 100A, that is, a side relatively far away from the optical interface.

[0074] Furthermore, in one embodiment, the chip mounting area D further includes a plurality of power pads 26; Figure 4 The photodetector 30 further includes a plurality of power supply electrodes 33 .

[0075] The power electrodes 33 correspond to the power pads 26 one by one. Each power electrode 33 is fixedly connected to the corresponding power pad 26 by flip-chip bonding.

[0076] That is, in the flip-chip connection state, the signal electrode 31S and the second signal pad 22S are directly connected, and at this time, each power electrode 33 and the corresponding power pad 26 are directly connected.

[0077] By providing the power electrode 33 and the power pad 26 , power supply between the photodetector 30 and the transimpedance amplifier 20 can be achieved.

[0078] In one embodiment, the chip mounting area D further includes a plurality of supporting pads 23; Figure 4 The photodetector 30 further includes a plurality of mechanical support pads 32 .

[0079] The plurality of mechanical support pads 32 correspond to the plurality of support pads 23 one by one, and each mechanical support pad 32 is fixedly connected to the corresponding support pad 23 by flip-chip bonding.

[0080] That is, in the flip-chip connection state, the signal electrode 31S and the second signal pad 22S are connected oppositely, and each mechanical support pad 32 and the corresponding support pad 23 are connected oppositely.

[0081] In this way, by setting the support pad 23 and the mechanical support pad 32, the fixed installation of the light detector 30 on the transimpedance amplifier 20 can be strengthened, and the position stability of the light detector 30 can be maintained, thereby facilitating stable and precise optical coupling between the light detector 30 and the optical element (such as the optical mirror 40 described later).

[0082] The support pad 23 is located at the front side of the chip mounting area D; the power pad 26 is located at the rear side of the chip mounting area D and is arranged side by side with the second signal pad 22S along a second direction perpendicular to the first direction (ie, the defined front-to-back direction).

[0083] In the accompanying drawings, the number of the power electrode 33, the power pad 26, the mechanical support pad 32, and the support pad 23 are all set to two. It can be understood that the present application is not limited thereto, for example, the number can be changed to one, three or more; of course, in a variant embodiment, only one of the power pad 26 and the support pad 23 can be set, and the other can be omitted; correspondingly, one of the mechanical support pad 32 and the power electrode 33 can be omitted.

[0084] Furthermore, the transimpedance amplifier 20 includes more than two chip mounting areas D, and the chip mounting areas D are distributed side by side along the second direction perpendicular to the front-to-back direction.

[0085] It can be understood that each chip mounting area D is adapted to mount a photo detector 30 .

[0086] That is to say, the optical module 100 has more than two photodetectors 30, which are mounted side by side on the transimpedance amplifier 20 along the second direction by flip-chip bonding. Thus, each photodetector 30 can convert an optical signal into an electrical signal, and the electrical signal is transmitted to the circuit board 10 via the transimpedance amplifier 20, so that the optical module 100 has multiple signal channels.

[0087] In the drawings, the number of the chip mounting areas D and the photodetectors 30 is set to 4, but the present application is not limited thereto and may be 2, 3, 6, 8 or even more.

[0088] In one embodiment, the transimpedance amplifier 20 further includes one or more second ground pads 24 .

[0089] The second ground pad 24 is located between two adjacent chip mounting areas D, and / or located on both sides of each chip mounting area D in the second direction.

[0090] To put it another way, that is, the second ground pad 24 is located between two adjacent photodetectors 30 and / or located on both sides of each photodetector 30 in the second direction.

[0091] The second ground pad 24 is electrically connected to the circuit board 10 through a bonding wire (the bonding wire is omitted in the figure). In this way, the transimpedance amplifier 20 and the circuit board 10 are directly grounded and electrically connected through the bonding wire near the photodetector 30, avoiding signal crosstalk between different signal channels, reducing impedance, and improving bandwidth and link rate.

[0092] Further, Figure 5 The transimpedance amplifier 20 also has a signal transmission line.

[0093] The signal transmission line has an amplifier circuit, and the amplifier circuit is used to amplify the electrical signal of the transimpedance amplifier.

[0094] The signal transmission line is electrically connected between the second signal pad 22S and the first signal pad 21S to transmit the power supply signal from the second signal pad 22S to the first signal pad 21S.

[0095] The signal transmission line is arranged between the second signal pad 22S and the first signal pad 21S in the front-to-back direction. In this way, the link impedance and inductance of the electrical signal from the second signal pad 22S to the first signal pad 21S via the signal transmission line are small, thereby facilitating the improvement of bandwidth and link rate.

[0096] In one embodiment, the signal transmission circuit includes a first surface circuit, an inner circuit 29 and a second surface circuit.

[0097] The first surface circuit is located on the surface of the transimpedance amplifier 20 and at least has a first signal pad 21S formed thereon.

[0098] Similarly, the second surface layer circuit is located on the surface of the transimpedance amplifier 20 , and at least a second signal pad 22S is formed thereon.

[0099] The inner layer line 29 is located inside the transimpedance amplifier 20 and includes the amplifying circuit of the transimpedance amplifier 20 ; one end of the inner layer line 29 is electrically connected to the second signal pad 22S through a conductive via 27 , and the other end thereof is electrically connected to the first signal pad 21S through a conductive via 28 .

[0100] In this way, this embodiment further reduces the impedance and inductance of the link through the provision of the inner layer line 29 and the two conductive vias 28 and 27, thereby improving the bandwidth and link rate.

[0101] More specifically, in the example of the accompanying drawings, the first signal pad 21S and the second signal pad 22S are located on the same surface 204 (see reference numerals) of the transimpedance amplifier 20 in the thickness direction. Figure 8 Correspondingly, the first surface layer circuit and the second surface layer circuit are located on the same surface 204 of the transimpedance amplifier 20 in the thickness direction.

[0102] For example, the transimpedance amplifier 20 has a first surface 204 and a second surface 203 opposite to each other in the thickness direction.

[0103] In a variation, the first signal pad 21S and the second signal pad 22S may be respectively located on different surfaces of the transimpedance amplifier 20 in the thickness direction compared to the example in the attached figure. For example, the second signal pad 22S is located on the first surface 204, and the first signal pad 21S is located on the second surface 203. Correspondingly, the first surface layer circuit and the second surface layer circuit are respectively located on different surfaces of the transimpedance amplifier 20 in the thickness direction. For example, the second surface layer circuit is located on the first surface 204, and the first surface layer circuit is located on the second surface 203.

[0104] Furthermore, the first signal pad 21S may be electrically connected to the signal line 11S of the circuit board 10 by welding, conductive adhesive bonding, wire bonding, or other feasible methods.

[0105] For example, as shown in the drawings, the first signal pad 21S is electrically connected to the signal line 11S of the circuit board 10 through the bonding wire 91 , so that the electrical signal is transmitted from the transimpedance amplifier 20 to the circuit board 10 .

[0106] Alternatively, in a variation embodiment different from the drawings, if the first signal pad 21S is located on the second surface 203 , the first signal pad 21S can be directly electrically connected to the signal line 11S of the circuit board 10 by welding or conductive adhesive.

[0107] In more detail, see Figure 3 The transimpedance amplifier 20 has at least one pad group 21 .

[0108] In this embodiment, the pad group 21 is configured as a ground-signal-ground-signal-ground (abbreviated as GSGSG in this application) structure, that is, it includes two first signal pads 21S, two first ground pads 21G located on both sides, and a first ground pad 21G located between the two first signal pads 21S.

[0109] Of course, in a variant embodiment, the pad group 21 can also be set to a ground-signal-signal-ground (GSSG for short in this application), that is, it includes two first signal pads 21S in the middle and two first ground pads 21G located on both sides. To put it another way, the first ground pad 21G located between the two first signal pads 21S in the embodiment of the accompanying drawings is omitted.

[0110] In another variation, the pad group 21 may also be configured as a ground-signal-ground (GSG for short in this application) structure, that is, including a first signal pad 21S in the middle and two first ground pads 21G on both sides.

[0111] Corresponding to the structure of the transimpedance amplifier 20, Figure 6 The circuit board 10 has at least one circuit group 11, and the at least one circuit group 11 corresponds to the at least one pad group 21 one by one.

[0112] In this embodiment, the line group 11 is configured as a ground-signal-signal-ground (hereinafter referred to as GSSG) structure, that is, it includes two signal lines 11S in the middle and two ground lines 11G on both sides.

[0113] Among them, between the corresponding pad group 21 and line group 11 : the first ground pad 21G is electrically connected to the ground line 11G through the bonding wire, and the first signal pad 21S is electrically connected to the signal line 11S through the bonding wire 91 .

[0114] In a variant embodiment, the line group 11 of the GSSG structure may also correspond to the pad group 21 of the GSSG structure.

[0115] Furthermore, in another variation embodiment, the line group 11 can also be set to a ground-signal-ground-signal-ground (abbreviated as GSGSG in this application) structure, that is, it includes two signal lines 11S, two grounding wires 11G located on both sides, and a grounding wire 11G located between the two signal lines 11S; the corresponding pad group 21 adopts a GSGSG structure, for example, and the corresponding first signal pad 21S and the signal line 11S, the corresponding first ground pad 21G and the grounding wire 11G are electrically connected through bonding wires.

[0116] In another variant embodiment, the line group 11 can also be set to a ground-signal-ground (GSG for short in this application) structure, that is, it includes a signal line 11S in the middle and two ground wires 11G on both sides; the corresponding pad group 21 adopts a GSG structure, for example, and the corresponding first signal pad 21S and signal line 11S, and the corresponding first ground pad 21G and ground wire 11G are electrically connected through bonding wires.

[0117] In addition, it can be understood that in addition to the GSSG structure, GSGSG structure and GSG structure introduced above, the pad group 21 can also be set to other known structures in the art including at least one signal pad and at least one ground pad, and the line group 11 can also be set to other known structures in the art including at least one signal line and at least one ground line, which are not enumerated.

[0118] As described above, in one embodiment, the first signal pad 21S is electrically connected to the signal line 11S of the circuit board 10 through the bonding wire 91. It can be understood that the number of bonding wires 91 between the first signal pad 21S and the corresponding signal line 11S can be one, two or more.

[0119] Ginseng Figure 6 In one embodiment, the bonding wire 91 between the first signal pad 21S and the corresponding signal line 11S is specifically configured as follows: the first signal pad 21S is electrically connected to the signal line 11S through four bonding wires 91A and 91B.

[0120] That is to say, Figure 6 In this example, the number of bonding wires 91 between the first signal pad 21S and the corresponding signal line 11S is set to four.

[0121] In this way, the electrical connection between the first signal pad 21S and the signal line 11S is realized through four bonding wires, which can greatly reduce the inductance, thereby reducing the impedance, and further improving the bandwidth and link rate.

[0122] The four bonding wires 91A and 91B are arranged such that, in the thickness direction of the circuit board 10 , the heights of two bonding wires 91A are greater than the heights of the other two bonding wires 91B.

[0123] For example, Figure 6 and Figure 7 The height of any bonding lead is defined by the maximum distance from the bonding lead to the signal line 11S of the circuit board 10 in the thickness direction of the circuit board 10. The maximum distance ha from the two bonding leads 91A to the signal line 11S in the thickness direction is greater than the maximum distance hb from the other two bonding leads 91B to the signal line 11S in the thickness direction.

[0124] In this way, by adopting a structural arrangement of four bonding wires 91A and 91B stacked in pairs, the inductance of the electrical connection between the first signal pad 21S and the signal line 11S can be reduced, the impedance can be reduced, and the bandwidth and link rate can be improved.

[0125] As described above, in the thickness direction of the circuit board 10 , two bonding leads 91A are taller and constitute upper bonding leads 91A, and the other two bonding leads 91B are shorter and constitute lower bonding leads 91B.

[0126] Furthermore, continue to participate Figure 6 In this embodiment, the spacing between the two solder joints P2A of the two upper bonding wires 91A at the first signal pad 21S is substantially consistent with the spacing between the two solder joints P1A at the signal line 11S. Similarly, the spacing between the two solder joints P2B of the two lower bonding wires 91B at the first signal pad 21S is substantially consistent with the spacing between the two solder joints P1B at the signal line 11S.

[0127] In a variant embodiment, the spacing between the two solder joints P2A of the two upper bonding wires 91A at the first signal pad 21S is smaller than the spacing between the two solder joints P1A at the signal line 11S. For example, the two upper bonding wires 91A are arranged in an eight-shaped pattern from the first signal pad 21S to the signal line 11S, that is, the spacing between the two solder joints P1A of the two upper bonding wires 91A at the signal line 11S is increased compared with the attached figure; for example, the signal line 11S has a first edge 11S1 and a second edge 11S2 that are arranged opposite to each other, and the solder joints P1A of the two upper bonding wires 91A are located at the first edge 11S1 and the second edge 11S2, respectively. In this way, the inductance can be further reduced, the impedance can be lowered, and the bandwidth and link rate can be improved.

[0128] Similarly, in a variant embodiment, the spacing between the two solder joints P2B of the two lower bonding wires 91B at the first signal pad 21S is smaller than the spacing between the two solder joints P1B at the signal line 11S. For example, the two lower bonding wires 91B are arranged in an eight-shaped pattern from the first signal pad 21S to the signal line 11S, that is, the spacing between the two solder joints P1B of the two lower bonding wires 91B at the signal line 11S is increased compared with the attached figure; for example, the two solder joints P1B of the two lower bonding wires 91B are located at the first edge 11S1 and the second edge 11S2, respectively. In this way, the inductance can be further reduced, the impedance can be lowered, and the bandwidth and link rate can be improved.

[0129] Furthermore, in the thickness direction of the circuit board 10 , the circuit board 10 has a first circuit board surface 101 and a second circuit board surface 102 that are oppositely arranged, and the at least one circuit group 11 is formed on the surface 101 .

[0130] In one embodiment, the transimpedance amplifier 20 is disposed on the circuit board 10 , that is, the circuit board 10 and the transimpedance amplifier 20 are arranged in a stacked manner along the thickness direction.

[0131] Specifically, the transimpedance amplifier 20 is fixedly mounted on the first circuit board surface 101 of the circuit board 10 .

[0132] Correspondingly, in the thickness direction of the circuit board 10, the difference Δh between the height of the four bonding leads from the circuit board 10 (i.e., from the first circuit board surface 101) and the height of the first signal pad 21S from the circuit board 10 (i.e., from the first circuit board surface 101) satisfies R<Δh<100μm, and more preferably R<Δh<50μm; wherein R is the diameter of the bonding lead.

[0133] In this way, when the circuit board 10 and the transimpedance amplifier 20 are stacked in the thickness direction of the circuit board, the impedance can be further reduced and the bandwidth and link rate can be improved by reasonably setting the height of the bonding wires.

[0134] In addition, as mentioned above, the transimpedance amplifier 20 is fixedly mounted on the first circuit board surface 101 of the circuit board 10. Specifically in this embodiment, the optical module 100 further comprises a conductive silver adhesive layer 12, and the transimpedance amplifier 20 is fixedly mounted on the ground pattern layer 10G (reference numeral 100) of the first circuit board surface 101 of the circuit board 10 by the conductive silver adhesive layer 12. Figure 5 ), thereby increasing the common potential.

[0135] In a variation of the embodiment, the transimpedance amplifier 20 may also be fixed on the circuit board 10 by flip-chip bonding or other methods, and is not limited to using the conductive silver paste layer 12 .

[0136] Of course, the positional relationship between the circuit board 10 and the transimpedance amplifier 20 of the utility model is not limited to being stacked in the thickness direction. For example, in a variant embodiment, the transimpedance amplifier 20 can also be changed to be arranged side by side with the circuit board 10, for example, the circuit board 10 and the transimpedance amplifier 20 are fixed side by side on the heat sink of the optical module in the front-to-back direction.

[0137] Furthermore, the pad group 21 is configured as a GSG structure, a GSGSG structure or a GSSG structure. In one pad group 21 , two first ground pads 21G located on both sides may be electrically connected via one, two or more bonding wires 92 .

[0138] In this way, the first ground pads 21G on both sides of a pad group 21 are electrically connected to avoid crosstalk between the signal channel formed by the pad group 21 and other signals outside the pad group 21 (such as signal channels of other pad groups 21), thereby improving bandwidth and link rate.

[0139] Furthermore, corresponding to the number of the photodetectors 30 and the number of the chip mounting areas D mentioned above, the number of the signal transmission lines and pad groups 21 of the transimpedance amplifier 20, and the number of the line groups 11 of the circuit board 10 are also set to more than two, and the specific number is consistent with the number of the photodetectors 30 and the number of the chip mounting areas D.

[0140] For example, the number can be set to 4 as shown in the figure, or it can be changed to 2, 3, 6 or other numbers.

[0141] Furthermore, in one embodiment, as shown in the figure, the adjacent first ground pads 21G of two adjacent pad groups 21 can be separately arranged; and in a variant embodiment, the adjacent first ground pads 21G of two adjacent pad groups 21 can also be changed into an integrated arrangement, for example Figure 3 Several first ground pads 21G in the middle dotted frame S are merged into one.

[0142] Furthermore, in one embodiment, continue to Figure 6 , the adjacent grounding wires 11G of two adjacent line groups 11 are arranged as one body; of course, in a variation embodiment, the adjacent grounding wires 11G of two adjacent line groups 11 may also be changed to be arranged separately.

[0143] In addition, the transimpedance amplifier 20 is provided with a plurality of power supply pads 25 at both side edges in the second direction, and the power supply pads 25 are electrically connected to the power supply circuit of the circuit board 10 or other power supply circuits of the optical module 100 through bonding wires (not shown in the figure).

[0144] Among them, the bonding wires mentioned in the present application can be set as metal conductive wires such as gold wires, silver wires, and copper wires.

[0145] The bonding wires mentioned in the present application can be set to have a diameter of 1 μm. Such a setting can reduce impedance, increase bandwidth and link rate while ensuring processing convenience and operability.

[0146] Further, in one embodiment, Figure 4 and Figure 5 The light detector 30 includes a first side surface 301 and a second side surface 302 disposed opposite to the first side surface 301 .

[0147] The signal electrode 31S is disposed on the first side surface 301 . The first side surface 301 is arranged toward the transimpedance amplifier 20 , while the second side surface 302 is arranged away from the transimpedance amplifier 20 .

[0148] Ginseng Figures 7 to 9 The light detector 30 includes an incident light window 34 disposed on one side of the second side surface 302. The light detector 30 receives the optical signal through the incident light window 34.

[0149] In this embodiment, by disposing the support pad 23 and the mechanical support pad 32 , the position and / or angle of the incident light window 34 relative to the photodetector 30 can be accurately adjusted so that the optical signal can be accurately incident on the incident light window 34 .

[0150] Furthermore, the optical module 100 further includes an optical mirror 40 accommodated in the housing 90 , and the optical mirror 40 is located on the light incident path of the light detector 30 .

[0151] Specifically, the optical mirror 40 includes a coupling lens 41 and a carrying body that carries the coupling lens 41 .

[0152] The optical signal received by the optical module 100 from the outside via the optical interface is coupled to the optical detector 30 via the coupling lens 41 , so that the optical signal is received by the optical detector 30 and converted into an electrical signal.

[0153] The optical module 100 further includes a support block 50 for fixing and supporting the optical mirror 40, and the support block 50 is fixed on the transimpedance amplifier 20. The optical mirror 40 is fixed on the support block 50 and extends to the light incident path of the photodetector 30, so that the coupling lens 41 is located on the light incident path of the photodetector 30.

[0154] In this way, by fixing the support block 50 for fixing the optical mirror 40 on the transimpedance amplifier 20, that is, the support block 50 and the transimpedance amplifier 20 are stacked instead of side by side, and the other end of the optical mirror 40 is suspended, it is only necessary to set the support block 50 at one end thereof, which can greatly reduce the occupied area, facilitate the miniaturization of optical module products, and facilitate improving the integration of optical modules, thereby helping to further improve the optical module rate within the standard optical module size and realize an ultra-high-speed optical module.

[0155] Furthermore, when the transimpedance amplifier 20 is stacked and fixed on the first circuit board surface 101 installed on the circuit board 10, by fixing the support block 50 on the transimpedance amplifier 20, or by fixing the optical detector 30 on the transimpedance amplifier 20, the space layout of the first circuit board surface 101 of the circuit board 10 can be saved, the wiring compactness of the circuit board 10 can be improved, and the possibility of product miniaturization can be further improved, which helps to improve the integration of the optical module, thereby facilitating the realization of an ultra-high-speed optical module.

[0156] For ease of understanding, the up and down directions are defined herein by the thickness direction of the circuit board 10 , wherein the first circuit board surface 101 is relative to the side where it is located and the second circuit board surface 102 is relative to the side where it is located and the direction is defined as “down”.

[0157] As mentioned above, the coupling lens 41 is used to couple the optical signal to the optical detector 30. More specifically, the coupling lens 41 can be arranged vertically opposite to the incident light window 34 of the optical detector 30 so that the light spot of the optical signal falls into the incident light window 34 as completely as possible.

[0158] Furthermore, the optical mirror 40 has a fixed area 401 and a suspended area 402 .

[0159] The fixed area 401 is fixed on the support block 50, that is, the fixed area 401 overlaps directly above the support block 50; the suspended area 402 extends laterally from the support block 50 and is suspended, that is, there is no support block 50 directly below the suspended area 402, and the coupling lens 41 is located in the suspended area 402.

[0160] Furthermore, the support block 50 is fixed on the transimpedance amplifier 20 by adhesive bonding, and the optical mirror 40 is fixed on a side of the support block 50 facing away from the transimpedance amplifier 20 by adhesive bonding.

[0161] In this installation and fixing method, the optical mirror 40, the support block 50, and the transimpedance amplifier 20 are stacked up and down, the structure is more compact, and the installation is simple and convenient.

[0162] In addition, in the present embodiment, the optical detector 30 adopts a surface receiving type device, and the light receiving direction of its incident light window 34 is perpendicular to the main axis of the light propagation path in the optical module 100. Correspondingly, the optical module 100 also includes an optical path deflector 60 having a reflecting mirror 61. Thus, on the light propagation path of the optical module 100, after the optical signal whose main axis is perpendicular to the up and down directions enters the optical path deflector 60, it is reflected at the reflecting mirror 61 and converted into an optical signal whose main axis is parallel to the up and down directions (or the main axis is perpendicular to the incident light window 34 of the optical detector 30), and then coupled to the optical detector 30 by the coupling lens 41.

[0163] The above describes that the optical mirror 40 including the coupling lens 41 shown in the example in the accompanying drawings is fixed on the support block 50, and the optical path deflector 60 and the coupling lens 41 are separately arranged; of course, in a variant embodiment, for example, the optical mirror may also include an integrated structure composed of an optical path deflector with a reflecting mirror surface (for example, the optical path deflector 60 in the accompanying drawings) and a coupling lens whose focus is located at the incident light window 34 of the light detector 30 (for example, the coupling lens 41 in the accompanying drawings is directly fixed on the optical path deflector 60), and the integrated structure is fixed on the support block 50 (for example, the optical path deflector 60 in the accompanying drawings is fixed on the support block 50, and at the same time, the reflecting mirror surface 61 of the optical path deflector 60 is suspended on the light incident path of the light detector 30, and the coupling lens 41 is fixed on the exit surface of the optical path deflector 61, and the light signal is reflected by the reflecting mirror surface 61 and then emitted to the coupling lens 61 through the exit surface of the optical path deflector 60). The above-mentioned variations of the implementation of the optical mirror 40 do not deviate from the technical purpose of the present application.

[0164] Further, in the front-rear direction, the support block 50 is located between the photodetector 30 and the first signal pad 21S.

[0165] In one embodiment, in an optical module including more than two optical detectors 30 , each optical detector 30 and a support block 50 are arranged side by side along the front-to-back direction, and the distance between any two optical detectors 30 and the support block 50 is equal.

[0166] Furthermore, the optical mirror 40 extends to the light incident path of each photodetector 30 , and the optical mirror 40 has two or more coupling lenses 41 corresponding to the two or more photodetectors 30 , and each coupling lens 41 is located on the light incident path of the corresponding photodetector 30 .

[0167] In this way, multiple coupling lenses 41 of the optical mirror 40 supported by the same support block 50 can simultaneously match at least two or more photodetectors 30, thereby further reducing the complexity of the assembly process, saving assembly area, and facilitating the miniaturization and high speed of the optical module.

[0168] Furthermore, the optical module 100 also includes any one or more of an optical fiber, an optical fiber jack, an optical attenuation element, an optical enhancement element, a collimating lens, a periscope, a wavelength division multiplexer, a focusing lens, and a coupling lens located in the light propagation path between the optical interface and the optical mirror 40.

[0169] Furthermore, the light detector 30 can be specifically configured as a PN photodiode, a PIN photodiode, an avalanche photodiode or a single-photon avalanche photodiode; from another perspective, the light detector 30 can be a waveguide diode or a silicon photodiode; from yet another perspective, the light detector 30 can be a single diode or an integrated diode.

[0170] The specific selection of the light detector 30 can be applied by any technique known in the art.

[0171] Furthermore, the circuit board 10 can be specifically configured as the circuit board 30 which can be a flexible circuit board, a rigid circuit board, or a rigid-flexible board in which multiple layers of rigid circuit boards and flexible circuit boards are pressed into one.

[0172] As mentioned above, the optical module of the present application has at least a light receiving function, and it is known that in one embodiment, the optical module 100 may be an optical receiver having only a light receiving function; and in another embodiment, the optical module 100 may also be an optical transceiver having both a light receiving function and a light transmitting function, so that the optical module 100 further includes an optical transmitter electrically connected to the circuit board 10, the optical transmitter is used to receive an electrical signal from the circuit board 10 and convert the electrical signal into an optical signal, and the optical signal is transmitted to an external device by the optical module 100. The optical transmitter may be a laser diode, such as an edge emitting laser diode, a Fabry-Perot (FP) laser, a vertical cavity surface emitting laser (VCSEL), a distributed feedback (DFB) laser or other suitable light sources.

[0173] Example 2

[0174] This embodiment provides an optical module. Fig.10 and Fig.11 The optical module 100 of this embodiment is different from the previous embodiment 1 in that the number of bonding wires between the first signal pad 21S and the corresponding signal line 11S and the arrangement shown in the figure are different. The following only describes the technical contents related to the differences. The rest of the technical contents except the differences are exactly the same as those of the previous embodiment 1 and will not be repeated.

[0175] In the foregoing first embodiment, the first signal pad 21S and the corresponding signal line 11S are electrically connected via four bonding wires.

[0176] In this embodiment, Fig.10 and Fig.11 The first signal pad 21S and the corresponding signal line 11S are electrically connected via two bonding wires 91 .

[0177] The spacing between the solder joints P2 of the two bonding wires 91 at the first signal pad 21S is smaller than the spacing between the solder joints P1 at the signal line 11S. This can optimize processing operability and reduce inductance and impedance, thereby improving bandwidth and link rate overall.

[0178] The two bonding wires 91 are arranged in an eight-shaped pattern from the first signal pad 21S to the signal line 11S.

[0179] For example, the signal line 11S has a first edge 11S1 and a second edge 11S2 that are arranged opposite to each other in a first direction, and the solder joints P1 of the two bonding wires 91 are located at the first edge 11S1 and the second edge 11S2 respectively.

[0180] In this way, the inductance can be further reduced, the impedance can be lowered, and the bandwidth and link rate can be improved.

[0181] In this embodiment, in the thickness direction of the circuit board 10, the difference Δh between the height of the two bonding wires 91 from the circuit board 10 (specifically, from the first circuit board surface 101) and the height of the first signal pad 21S from the circuit board 10 (specifically, from the first circuit board surface 101) satisfies R<Δh<100μm, more preferably R<Δh<50μm. Wherein, R is the diameter of the bonding wire.

[0182] In this way, when the circuit board 10 and the transimpedance amplifier 20 are stacked in the thickness direction, the impedance can be further reduced and the bandwidth and link rate can be improved by setting the height of the bonding wire 91.

[0183] As mentioned above, except for the differences, the optical module 100 of this embodiment is completely the same as that of the previous embodiment 1, and will not be described again.

[0184] In summary, compared with the prior art, the beneficial effect of the utility model is at least that: the first signal pad of the transimpedance amplifier is electrically connected to the circuit board, the optical detector is electrically connected to the second signal pad of the chip mounting area of ​​the transimpedance amplifier through flip-chip welding, and the second signal pad is arranged on the side of the chip mounting area close to the first signal pad, so that the transmission position of the electrical signal from the optical detector to the transimpedance amplifier is close to the first signal pad, and thus, the high-speed link of the optical module 100 has a smaller inductance, which reduces the impedance, thereby facilitating the improvement of bandwidth and link rate.

[0185] It should be understood that although this specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each implementation mode may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

[0186] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the utility model and are not intended to limit the protection scope of the utility model. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the utility model should be included in the protection scope of the utility model.

Claims

1. An optical module, comprising: Circuit boards; A photodetector for converting optical signals into electrical signals; and A transimpedance amplifier having a chip mounting area for flip-chip bonding of the photodetector and a first signal pad electrically connected to the circuit board; It is characterized in that the photodetector is arranged in the chip mounting area, the chip mounting area includes a second signal pad electrically connected to the first signal pad, the second signal pad is electrically connected to the signal electrode of the photodetector, and the second signal pad is located on a side of the chip mounting area adjacent to the first signal pad.

2. The optical module according to claim 1, characterized in that: The transimpedance amplifier comprises a front edge and a rear edge which are arranged opposite to each other, the first signal pad is relatively close to the rear edge, and the chip mounting area is relatively close to the front edge; The second signal pad is located at a rear side of the chip mounting area.

3. The optical module according to claim 2, characterized in that: The transimpedance amplifier also has a signal transmission line, and the signal transmission line has an amplification circuit for amplifying the electrical signal of the transimpedance amplifier; The signal transmission line is electrically connected between the second signal pad and the first signal pad, and is arranged between the second signal pad and the first signal pad in a front-to-rear direction.

4. The optical module according to claim 3, characterized in that: The signal transmission circuit comprises: A first surface circuit, formed with the first signal pad; A second surface layer circuit is formed with the second signal pad; and The inner layer circuit is located inside the transimpedance amplifier, the inner layer circuit includes the amplifier circuit, and two ends of the inner layer circuit are electrically connected to the second signal pad and the first signal pad through conductive holes.

5. The optical module according to claim 2, characterized in that: The chip mounting area also includes: a support pad, the support pad being located at a front side of the chip mounting area; and / or, a power pad, the power pad being located at the rear side of the chip mounting area and arranged side by side with the second signal pad; The light detector further comprises: a mechanical support pad flip-chip fixed to the support pad; and / or, A power electrode is electrically connected to the power pad by flip-chip bonding.

6. The optical module according to claim 2, characterized in that: The number of the chip mounting areas is more than two, and the more than two chip mounting areas are distributed side by side along a second direction perpendicular to the front-to-back direction; The transimpedance amplifier further includes a second ground pad located between two adjacent chip mounting areas or located on both sides of any chip mounting area in the second direction, and the second ground pad is electrically connected to the circuit board.

7. The optical module according to claim 1, characterized in that: The first signal pad is electrically connected to the signal line of the circuit board through welding, conductive glue or bonding wire.

8. The optical module according to claim 7, characterized in that: The optical module also has a conductive silver glue layer, and the transimpedance amplifier is adhered to the ground pattern layer on the surface of the circuit board through the conductive silver glue layer.

9. The optical module according to claim 7, characterized in that: The first signal pad is electrically connected to the signal line of the circuit board through four bonding wires; In the thickness direction of the circuit board, heights of two of the four bonding wires are greater than heights of the other two.

10. The optical module according to claim 7, characterized in that: The first signal pad is electrically connected to the signal line of the circuit board through two bonding wires; The distance between two solder joints of the two bonding wires at the first signal pad is smaller than the distance between two solder joints at the signal line.

11. The optical module according to claim 1, characterized in that: The transimpedance amplifier includes a pad group; The pad group includes the first signal pad and at least two first ground pads, and is arranged in a GSG structure, a GSSG structure or a GSGSG structure, wherein the two first ground pads on both sides of the pad group are electrically connected via bonding wires.

12. The optical module according to claim 1, characterized in that: The transimpedance amplifier is disposed on the circuit board, or the transimpedance amplifier and the circuit board are arranged side by side.

13. The optical module according to claim 1, characterized in that: The transimpedance amplifier is fixedly mounted on the surface of the circuit board; The first signal pad is electrically connected to the signal line of the circuit board through a bonding wire, and in the thickness direction of the circuit board, the difference between the height of the bonding wire from the circuit board and the height of the first signal pad from the circuit board is less than 100 μm.

14. The optical module according to claim 1, characterized in that: The optical module further comprises an optical mirror and a support block, wherein the support block is fixed on the transimpedance amplifier, and the optical mirror is fixed on the support block and extends to the light incident path of the light detector.

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