Double-ended EML COC assembly

Abstract

A double-ended EML COC assembly, comprising: a ceramic substrate (102), which is provided with a gold-tin eutectic region (301), first to third common grounding regions (302-1, 302-2, 302-3), a high-frequency positive signal line (303), a high-frequency negative signal line (304), first and second matching resistors (305, 306), high-frequency pin bonding pads (307, 308), a laser pin bonding pad (309), first to third signal line gaps (310, 311-1, 311-2), output grounding pin pads (312-1, 312-2, 312-3), high-frequency signal line output pin pads (313, 314), a via hole (305), and a substrate (316), wherein the first to third common grounding regions (302-1, 302-2, 302-3) are regions which are in communication with one another; an EML chip (101), which is located directly above the gold-tin eutectic region (301); and a filter capacitor (103), which is located in the first common grounding region (302-1), wherein there is a gap between the filter capacitor (103) and the gold-tin eutectic region (301). The high-frequency positive signal line (303) and the high-frequency negative signal line (304) are designed beside an EML chip pin side by side, and each signal line includes a high-frequency signal line output pin pad (313 / 314), such that a double-ended differential COC assembly is formed, thereby improving the integrity of a high-frequency signal of an EML assembly, and thus increasing the bandwidth of the EML assembly.

Description

Double-ended EML COC components Technical Field

[0001] The present invention relates to the technical field of optical modules, and in particular to a double-ended EML COC component. Background Art

[0002] Transmitters used in optical communications are core components of optical modules, and the COC (Chip on Carrier) assembly is a key component of these devices. The structure and performance of the COC assembly are crucial to the high-frequency and thermal performance of both the optical device and the module. This is particularly true for high-speed optical modules and those with long transmission distances, such as 400G and 800G. These high-speed optical modules utilize COC assemblies based on EML (Electro-absorption Modulated Laser) lasers. EML laser chips are widely used due to their excellent spectral and chirp characteristics. For the COC component of the EML laser, since the EML laser chip has only one high-frequency pin pad as the output port, the high-frequency pin pad is electrically interconnected with the high-frequency components in the optical device (such as ceramic substrates, TO bases, BOX ceramic parts) through good conductors such as gold wire, forming a GSG (Ground, Signal, Ground) type high-frequency transmission signal transmission structure, such as patents CN113552674A, CN217718170U, CN202310590348.X, US16555363, etc. This structure is suitable for the transmission of most high-frequency signals.

[0003] However, the COC component (including the EML laser chip) is used in conjunction with the high-frequency driver chip (Driver chip, DSP chip) on the PCBA in the optical module assembly, such as CN112505855A. When the COC component and the high-frequency driver chip are not well matched, the high-frequency performance of this single-ended COC component cannot meet the requirements of the optical module.

[0004] Double-ended EML COC components offer superior high-frequency transmission performance and better match performance with high-frequency driver chips. Currently, there are few double-ended solutions on the market. For example, patent CN217693343U proposes a double-ended design, but the other end (5015 port) is overly simple in its structure and fails to account for the equal transmission distance of differential signal lines, resulting in poor signal matching.

[0005] Summary of the Invention

[0006] The main purpose of the present invention is to provide a double-ended EML COC component, aiming to solve the technical problems of existing COC components such as poor matching with high-frequency driver chips and poor signal matching.

[0007] To achieve the above object, the present invention provides a double-ended EML COC assembly, comprising:

[0008] A ceramic substrate, comprising a gold-tin eutectic region, a first common ground region, a second common ground region, a third common ground region, a first signal line, a second signal line, a first matching resistor, a second matching resistor, a high-frequency pin pad, a laser pin pad, a first signal line gap, a second signal line gap, a third signal line gap, an output ground pin pad, a high-frequency signal line output pin pad, a via, and a substrate; wherein the first common ground region, the second common ground region, and the third common ground region are interconnected; the first signal line and the second signal line are arranged in parallel, and each signal line includes one of the high-frequency signal line output pin pads;

[0009] An EML chip is located directly above the gold-tin eutectic region;

[0010] A filter capacitor is located in the first common grounding region, and a gap exists between the filter capacitor and the gold-tin eutectic region.

[0011] In some embodiments, the first signal line and the second signal line are both in a straight line pattern, and the signal paths of the first signal line and the second signal line extend along a first direction;

[0012] Along a second direction perpendicular to the first direction, the third common ground area, the second signal line gap, the second signal line, the second matching resistor, the third signal line gap, the second common ground area, the first signal line gap, the first signal line, the first common ground area, the laser pin pad, the first matching resistor and the high-frequency pin pad are arranged in sequence.

[0013] In some embodiments, the EML chip includes a high-frequency pin pad, a laser pad, a first light-emitting surface, and a second light-emitting surface; the EML chip is provided with adjacent EAM regions and DFB regions; wherein,

[0014] The EAM region and the DFB region are arranged sequentially along the first direction;

[0015] The high-frequency pin pad and the first light-emitting surface are located in the EAM region, and the laser pad and the second light-emitting surface are located in the DFB region.

[0016] In some embodiments, the output ground pin pad includes a first output GND pin pad, a second output GND pin pad, and a third output GND pin pad; wherein,

[0017] The first output GND pin pad, the second output GND pin pad, the third output GND pin pad, the high-frequency signal line output pin pad and the laser pin pad are all located on the other side of the substrate opposite to the EML chip, serving as electrical input and output interfaces of the double-ended EML COC component.

[0018] In some embodiments, the first common ground region, the second common ground region, and the third common ground region are located in the outer region, and semi-enclose the second signal line gap, the second signal line, the second matching resistor, the third signal line gap, the first signal line gap, and the first signal line;

[0019] The gold-tin eutectic region is arranged on the upper surface of the first common ground region and is higher than the first common ground region;

[0020] The first common ground area, the second common ground area, the third common ground area, the first signal line, the second signal line, the first matching resistor, the second matching resistor, the high-frequency pin pad, the laser pin pad, the first signal line gap, the second signal line gap, the third signal line gap, the first output GND pin pad, the second output GND pin pad, the third output GND pin pad and the high-frequency signal line output pin pad are all located in the same plane and are all located on the upper surface of the substrate.

[0021] In some embodiments, the width of the second signal line slot, the width of the third signal line slot, the line width of the second signal line, the thickness and dielectric constant of the substrate, the intermediate reference ground, and the common ground constitute a first single-ended coplanar waveguide structure to form a first characteristic impedance, and the first characteristic impedance is 50 ohms;

[0022] The width of the first signal line gap, the line width of the first signal line, the thickness and dielectric constant of the substrate, the intermediate reference ground and the common ground constitute a second single-ended coplanar waveguide structure, forming a second characteristic impedance, which is 50 ohms.

[0023] In some embodiments, the characteristic impedance of the driver chip of the EML chip is 100 ohms, and the first matching resistor and the second matching resistor respectively use a single-ended impedance of 50 ohms and form a differential impedance of 100 ohms.

[0024] In some embodiments, the output ground pin pad includes a fourth output GND pin pad and a fifth output GND pin pad; wherein,

[0025] The fourth output GND pin pad, the fifth output GND pin pad, the high-frequency signal line output pin pad and the laser pin pad are all located on the other side of the substrate opposite to the EML chip, serving as electrical input and output interfaces of the double-ended EML COC component.

[0026] In some embodiments, the first common ground region, the second common ground region, and the third common ground region are located in the outer region, and semi-enclose the second signal line gap, the second signal line, the second matching resistor, the third signal line gap, the first signal line gap, and the first signal line;

[0027] The gold-tin eutectic region is arranged on the upper surface of the first common ground region and is higher than the first common ground region;

[0028] The first common ground area, the second common ground area, the third common ground area, the first signal line, the second signal line, the first matching resistor, the second matching resistor, the high-frequency pin pad, the laser pin pad, the first signal line gap, the second signal line gap, the third signal line gap, the fourth output GND pin pad, the fifth output GND pin pad and the high-frequency signal line output pin pad are all located in the same plane and are all located on the upper surface of the substrate.

[0029] In some embodiments, the fourth output GND pin pad and the fifth output GND pin pad, the high-frequency signal line output pin pad, and the second signal line slot and the third signal line slot together constitute a differential coplanar waveguide structure.

[0030] The present invention proposes a double-terminal EML COC component, comprising: a ceramic substrate, on which is provided a gold-tin eutectic region, a first common ground region, a second common ground region, a third common ground region, a first signal line, a second signal line, a first matching resistor, a second matching resistor, a high-frequency pin pad, a laser pin pad, a first signal line gap, a second signal line gap, a third signal line gap, an output ground pin pad, a high-frequency signal line output pin pad, a via, and a substrate; wherein the first common ground region, the second common ground region, and the third common ground region are interconnected regions; the first signal line and the second signal line are designed in parallel, and each signal line includes one of the high-frequency signal line output pin pads; an EML chip is located directly above the gold-tin eutectic region; a filter capacitor is located in the first common ground region, and there is a gap between the filter capacitor and the gold-tin eutectic region. The present invention designs a first signal line and a second signal line in parallel next to the EML chip pins. Each signal line includes a high-frequency signal line output pin pad to form a double-ended differential COC component. This can improve the high-frequency signal integrity of the EML component and further increase the bandwidth of the EML component, solving technical problems such as poor compatibility with high-frequency driver chips and poor signal matching in existing COC components. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG1 is a schematic structural diagram of a GSGSG double-ended EML COC assembly according to an embodiment of the present invention;

[0032] FIG2 is a schematic diagram of an EML chip of a double-ended EML COC assembly according to an embodiment of the present invention;

[0033] FIG3 is a schematic diagram of a GSGSG double-terminal substrate according to an embodiment of the present invention;

[0034] FIG4 is a schematic cross-sectional view of a substrate of a double-ended EML COC assembly according to an embodiment of the present invention;

[0035] FIG5 is a schematic diagram of the interconnection between the GSGSG COC component and the external electrical interface according to an embodiment of the present invention;

[0036] FIG6 is a simplified circuit diagram of the interconnection between the GSGSG COC component and the external electrical interface according to an embodiment of the present invention;

[0037] FIG7 is a schematic diagram illustrating the interconnection between a COC component with a DC-block capacitor and an external electrical interface according to an embodiment of the present invention;

[0038] FIG8 is a simplified circuit diagram of the interconnection between a COC component with a DC-block capacitor and an external electrical interface according to an embodiment of the present invention;

[0039] FIG9 is a schematic diagram of a bandwidth simulation curve of a COC component with GSGSG and an external electrical interface according to an embodiment of the present invention;

[0040] FIG10 is a schematic diagram of a GSSG double-ended EML COC assembly according to an embodiment of the present invention;

[0041] FIG11 is a schematic diagram of a substrate of a GSSG double-ended EML COC assembly according to an embodiment of the present invention;

[0042] FIG12 is a schematic diagram of the interconnection between the GSSG COC component and the external electrical interface according to an embodiment of the present invention;

[0043] FIG13 is a simplified circuit diagram of the interconnection between the GSSG COC assembly and the external electrical interface according to an embodiment of the present invention.

[0044] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0045] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0046] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0047] In addition, the descriptions of "first", "second", etc. in the present invention are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention. It should be understood that the specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0048] The present invention provides a double-ended EML COC component.

[0049] 1 , which is a schematic structural diagram of a double-ended EML COC assembly according to an embodiment of the present invention.

[0050] As shown in FIG1 , the double-ended EML COC assembly includes:

[0051] A ceramic substrate 102 is provided with a gold-tin eutectic region 301, a first common ground region 302-1, a second common ground region 302-2, a third common ground region 302-3, a first signal line, a second signal line, a first matching resistor, a second matching resistor, a high-frequency pin pad, a laser pin pad, a first signal line gap, a second signal line gap, a third signal line gap, an output ground pin pad, a high-frequency signal line output pin pad, a via, and a substrate; wherein the first common ground region, the second common ground region, and the third common ground region are interconnected; the first signal line and the second signal line are arranged in parallel, and each signal line includes one of the high-frequency signal line output pin pads;

[0052] The EML chip 101 is located directly above the AuSn eutectic region 301 ;

[0053] The filter capacitor 103 is located in the first common grounding region, and there is a gap between the filter capacitor and the gold-tin eutectic region.

[0054] It should be noted that this embodiment provides a double-ended EML (Electro-absorption Modulated Laser) COC (Chip On Carrier) assembly, also known as a differential EML COC assembly. The EML is arranged on a ceramic carrier, and high-frequency traces are arranged on the upper surface of the ceramic carrier. The high-frequency traces are distributed using pins such as GSGSG (Ground, Signal, Ground, Signal, Ground) and GSSG (Ground, Signal, Signal, Ground). Pin pads are provided at the ends of the ceramic carrier to form a double-ended distributed high-frequency signal line structure. This structure has the advantages of high bandwidth, excellent high-frequency signal integrity, low cost, simple structure, and high reliability. It can be applied to optical devices and modules in the field of optical communications and is widely used in many EML laser scenarios, such as CWDM and LWDM wavelengths. It can be packaged in modules such as QSFP DD, QSFP56, QSFP112, and OSFP.

[0055] This embodiment is described using the example of a first signal line 303 being a high-frequency positive signal line and a second signal line being a high-frequency negative signal line. In this embodiment, the high-frequency traces are arranged using pinouts such as GSGSG and GSSG. The following describes GSGSG and GSSG COC components, respectively.

[0056] Example 1: GSGSG type COC assembly:

[0057] Specifically, the double-ended EML COC assembly, as shown in Figure 1, includes an EML chip 101, a ceramic substrate 102, and a filter capacitor 103. Referring to Figures 1 and 2, a gold-tin eutectic region 301 and a first common ground region 302-1 (common GND) are provided on the top surface of the ceramic substrate 102. The EML chip 101 is positioned directly above the gold-tin eutectic region 301 and can be secured via gold-tin eutectic soldering. The front light-emitting surface 203 of the EML chip 101 faces the left side of the ceramic substrate 102. The filter capacitor 103 is positioned on the top surface of the first common ground region 302-1 (common GND), directly below it as shown in Figure 1, and spaced apart from the gold-tin eutectic region 301. The filter capacitor 103 is secured via gold-tin eutectic soldering or conductive adhesive.

[0058] It can be understood that, in actual applications, if necessary, a double-ended EML COC component is provided with an MPD backlight chip (not shown in the figure) on the right side of the rear light-emitting surface 204 of the EML chip 101 and on the upper surface of the first common ground area 302-1 (common GND), and the MPD backlight chip is fixed by gold-tin eutectic soldering or conductive adhesive bonding.

[0059] 2 , in some embodiments, the EML chip 101 includes a high-frequency pin pad, a laser pad, a first light-emitting surface, and a second light-emitting surface; the EML chip is provided with adjacent EAM regions and DFB regions; wherein,

[0060] The EAM region and the DFB region are arranged sequentially along the first direction;

[0061] The high-frequency pin pad and the first light-emitting surface are located in the EAM region, and the laser pad and the second light-emitting surface are located in the DFB region.

[0062] Specifically, as shown in Figure 2, the EML chip 101 is a rectangular parallelepiped and includes a high-frequency pin pad 201, a laser pad 202, a first or front light-emitting surface 203, and a second or rear light-emitting surface 204. Functionally, the EML chip includes an electroabsorption modulator (EAM) region and a distributed feedback laser (DFB) region. In Figure 2, the dotted line 205 is used as the dividing line, with the EAM region on the left and the DFB region on the right. The high-frequency pin pad 201 and the first or front light-emitting surface 203 are located in the EAM region, while the laser pad 202 and the second or rear light-emitting surface 204 are located in the DFB region.

[0063] Specifically, as shown in FIG3 , the ceramic substrate 102 includes a gold-tin eutectic region 301, a common GND region (i.e., a first common ground region 302-1), a second common ground region 302-2, and a third common ground region 302-3, a high-frequency positive signal line 303, a high-frequency negative signal line 304, a first matching resistor 305, a second matching resistor 306, high-frequency pin pads (307, 308), a laser pin pad 309, signal line slots (i.e., a first signal line slot 310, a second signal line slot 311-1, and a third signal line slot 311-2), output ground pin pads (i.e., output GND pin pads (312-1, 312-2, and 312-3), high-frequency signal line output pin pads (313, 314), a via 315, and a substrate 316. The common GND region (i.e., the first common ground region 302-1, the second common ground region 302-2, and the third common ground region 302-3) are interconnected.

[0064] In some embodiments, for a GSGSG type COC component: the output ground pin pad includes a first output GND pin pad, a second output GND pin pad, and a third output GND pin pad; wherein,

[0065] The first output GND pin pad, the second output GND pin pad, the third output GND pin pad, the high-frequency signal line output pin pad and the laser pin pad are all located on the other side of the substrate opposite to the EML chip, serving as electrical input and output interfaces of the double-ended EML COC component.

[0066] In some embodiments, referring to FIG3 , the first signal line and the second signal line both adopt a straight line pattern, and the signal paths of the first signal line and the second signal line extend along a first direction;

[0067] Along a second direction perpendicular to the first direction, the third common ground area, the second signal line gap, the second signal line, the second matching resistor, the third signal line gap, the second common ground area, the first signal line gap, the first signal line, the first common ground area, the laser pin pad, the first matching resistor and the high-frequency pin pad are arranged in sequence.

[0068] Specifically, as shown in Figure 3, the X direction in Figure 3 is the first direction and the Y direction is the second direction. Observing from top to bottom along the second direction, they are, in order, the third common ground area 302-3 (common GND), the second signal line gap 311-1, the second signal line, i.e., the high-frequency negative signal line 304 and the second matching resistor 306, the third signal line gap 311-2, the second common ground area 302-2 (common GND), the first signal line gap 310, the first signal line, i.e., the high-frequency positive signal line 303, the first common ground area 302-1 (common GND), the laser pin pad 309, the first matching resistor 305 and the high-frequency pin pad 307.

[0069] The common GND (302-1, 302-2, 302-3) is located at the outer edge, semi-enclosing the second signal line slot 311-1, the high-frequency negative signal line 304, the second matching resistor 306, the third signal line slot 311-2, the first signal line slot 310, and the high-frequency positive signal line 303. The gold-tin eutectic region 301 is provided on the upper surface of the first common ground region 302-1 (common GND) and is higher than the first common ground region 302-1 (common GND). The common GND (302-1, 302-2, 302-3), the high-frequency positive signal line 303, the high-frequency negative signal line 304, the first matching resistor 305, the second matching resistor 306, the high-frequency pin pads 307, 308, the laser pin pad 309, the signal line gaps (310, 311-1, 311-2), the output GND pin pads (312-1, 312-2, 312-3) and the high-frequency signal line output pin pads (313, 314) are all located in the same plane and are all located on the upper surface of the substrate 316. They can all use the same film material, such as Ti / pt / Au, with a thickness of micron level. The only difference is the pattern size. The via 315 is filled with conductive material, including but not limited to copper, silver, tungsten and other materials, for connecting the common GND (302-1, 302-2, 302-3) and the intermediate reference GND401, and passes through the first ceramic layer 316-1 of the substrate (as shown in FIG4).

[0070] Specifically, a gold-tin eutectic region 301 is pre-deposited on the upper surface of the first common ground region 302-1 (common GND) via electroplating, evaporation, or sputtering. It is a micron-level thin film material with a thickness of approximately 2 to 10 μm. A first matching resistor 305 and a second matching resistor 306 can be thin film resistors made of the same material and using the same process. They are pre-determined on the upper surface of the substrate 316. The first matching resistor 305 connects the high-frequency pin pad 307 to the first common ground region 302-1 (common GND), while the second matching resistor 306 connects the high-frequency negative signal line 304 to the third common ground region 302-3 (common GND).

[0071] Specifically, both the high-frequency positive signal line 303 and the high-frequency negative signal line 304 employ a linear pattern. The high-frequency positive signal line 303 includes a high-frequency pin pad 308, a linear waveguide, and a high-frequency signal line output pin pad 313. The high-frequency pin pad 308 is located on the left side, near the gold-tin eutectic region 301. The high-frequency negative signal line 304 includes a linear waveguide and a high-frequency signal line output pin pad 314. A second matching resistor 306 is positioned to the left of the high-frequency negative signal line 304. Between the second common ground region 302-2 and the third common ground region 302-3 are a second signal line gap 311-1, a third signal line gap 311-2, the high-frequency negative signal line 304, and the second matching resistor 306. The second signal line gap 311-1 and the third signal line gap 311-2 further surround the high-frequency negative signal line 304 and the second matching resistor 306. Between the first common ground region 302-1 and the second common ground region 302-2 is a first signal line gap 310 and a high-frequency positive signal line 303. The output GND pin pads (312-1, 312-2, 312-3), the high-frequency signal line output pin pads (313, 314), and the laser pin pads 309 are all located on the right side of the substrate, serving as the electrical input and output interfaces of the COC assembly. The width of the output GND pin pads (312-1, 312-2, 312-3) and the high-frequency signal line output pin pads (313, 314) is greater than 150 μm, meeting the bonding requirements of two gold wires.

[0072] Regarding the high-frequency characteristic impedance, the width W1 of the second signal line slot 311-1 and the third signal line slot 311-2, the line width W2 of the high-frequency negative signal line 304, the thickness T and dielectric constant of the substrate, the intermediate reference GND 401, and the common GNDs (302-1, 302-2, 302-3) together form a single-ended coplanar waveguide structure, forming the required characteristic impedance, typically 50 ohms. Similarly, the width W3 of the first signal line slot 310, the line width W2 of the high-frequency positive signal line 303, the thickness T and dielectric constant of the substrate, the intermediate reference GND 401, and the common GNDs (302-1, 302-2, 302-3) together form a single-ended coplanar waveguide structure, forming the required characteristic impedance, typically 50 ohms.

[0073] Typically, the characteristic impedance of the driver chip of the EML laser chip is 100 ohms. To match the characteristic impedance, the first matching resistor 305 and the second matching resistor 306 respectively use a single-ended impedance of 50 ohms and form a differential impedance of 100 ohms.

[0074] It should be noted that the output GND pin pads (312-1, 312-2, 312-3) and the high-frequency signal line output pin pads (313, 314) also meet the characteristic impedance requirements. Since the output GND pin pads (312-1, 312-2, 312-3) and the high-frequency signal line output pin pads (313, 314) need to be made wider due to gold wire bonding, the gaps of the second and third signal line gaps (311-1, 311-2) are adjusted accordingly. To reduce reflection, a trapezoidal structure with a gradually changing width is provided between the straight waveguide area of ​​the high-frequency positive signal line 303 and the high-frequency negative signal line 304 and the high-frequency signal line output pin pads (313, 314) for transition. In addition, to ensure that the differential high-frequency signal transmission distance is close, the lengths of the high-frequency positive signal line 303 and the high-frequency negative signal line 304 are substantially equal. In order to obtain good high-frequency characteristics, the size of the high-frequency pin pad 308 is increased to form an equivalent capacitor, and the equivalent inductance and equivalent resistance of the gold wire of the EML chip are added to form an RLC circuit to reduce the loss of high-frequency signals.

[0075] For example, the laser pin pad 309 is located at the lower right corner of the substrate (as shown in FIG3 ), and is disconnected from the common GND ( 302 - 1 , 302 - 2 , 302 - 3 ) by a gap. In addition, for process considerations, a narrow blank area is reserved around the outer edge of the upper surface of the substrate 316 .

[0076] Specifically, the material of substrate 316 includes, but is not limited to, AlN ceramic and high-resistance silicon. Substrate 316 employs a double-layer or multi-layer structure. This embodiment uses a double-layer ceramic structure as an example. As shown in FIG4 , substrate 316 comprises a first ceramic layer 316-1, a second ceramic layer 316-2, an intermediate reference GND 401, a bottom reference GND 402, and vias 315. Vias 315 are distributed in the common GND (302-1, 302-2, 302-3) region and comprise multiple independent vias. The via diameter is not limited, preferably 0.1 mm in diameter. The number of vias is also not limited. As shown in FIG3 , there are 18 vias, all of which penetrate the first ceramic layer 316-1 and provide conductive connections between the common GND (302-1, 302-2, 302-3) and the intermediate reference GND 401. As shown in Figure 4, from top to bottom, the following are the top surface common GND (302-1, 302-2, 302-3), the first ceramic layer 316-1, the intermediate reference GND 401, the second ceramic layer 316-2, and the bottom reference GND 402. If necessary, the second ceramic layer 316-2 can also be provided with vias to provide electrical connection between the intermediate reference GND 401 and the bottom reference GND 402.

[0077] Correspondingly, the COC component is electrically interconnected with the electrical interface pins in the PCBA or BOX shell of the optical module, as shown in Figure 5. An external electrical interface pin plate (501-506) is set on the right side of the EML COC component. The input and output pins 309, 312, 313 and 314 of the COC are electrically interconnected with the electrical interface pin plates (501-506) through gold wires (507-512), one to one. The corresponding relationship is as follows: the output GND pin plate 312-1, the gold wire 507 and the electrical interface GND pin plate 501 are a group; the high-frequency signal line output pin plate 314, the gold wire 508 and the electrical The interface differential negative pin pad 502 forms a group; the output GND pin pad 312-2, gold wire 509, and electrical interface GND pin pad 503 form a group; the high-frequency signal line output pin pad 313, gold wire 510, and electrical interface differential positive pin pad 504 form a group; the output GND pin pad 312-3, gold wire 511, and electrical interface GND pin pad 505 form a group; and the laser pin pad 309, gold wire 512, and electrical interface laser pin pad 506 form a group. Specifically, the gold wires (507-511) are all double-wired, while gold wire 512 is a single-wired.

[0078] It's understandable that the COC assembly itself also has gold wire interconnects. The high-frequency pin pad 201 of the EML chip 101 is interconnected to the high-frequency pin pad 308 via gold wire 513. The high-frequency pin pad 201 is interconnected to the high-frequency pin pad 307 via gold wire 514. The laser pad 202 is interconnected to the filter capacitor 103 via gold wire 515. The filter capacitor 103 is interconnected to the laser pin pad 309 via gold wire 516. Gold wires 513 and 516 are all single wires; gold wire 513 can be doubled if necessary.

[0079] It should be noted that the equivalent circuit of Figure 5 is shown in Figure 6. The EML chip 101 is equivalent to an EAM 601 and a DFB 602. The EAM 601 and DFB 602 are connected to GND. The EAM 601 is connected in parallel with a first matching resistor 305. A second matching resistor 306 is connected in series between the high-frequency positive signal line 304 and the common GND 302-3. The DFB 602 is connected in parallel with the filter capacitor 103.

[0080] Similarly, a modified structure is described: the high-frequency pin pad 307 is enlarged, for example, to a length greater than 0.45 mm, and the first matching resistor 305 is shifted to the right. A DC-block capacitor 701 is surface-mounted on the high-frequency pin pad 307. As shown in Figures 7 and 8, the DC-block capacitor 701 is connected in series with the first matching resistor 305. This RC circuit forms a high-frequency impedance match.

[0081] As shown in Figure 9, the bandwidth simulation curve of the GSGSG COC component and the external electrical interface (PCBA) shows a 3dB bandwidth of 49 GHz. When matched with an EML chip from a certain manufacturer in the industry, the bandwidth is approximately 49 GHz, which is fully sufficient for 100G PMA4 applications.

[0082] Example 2: GSSG type COC assembly:

[0083] Specifically, for a GSSG type COC component, in some embodiments, the output ground pin pad includes a fourth output GND pin pad 1002-1 and a fifth output GND pin pad 1002-2; wherein,

[0084] The fourth output GND pin pad 1002-1, the fifth output GND pin pad 1002-2, the high-frequency signal line output pin pad and the laser pin pad are all located on the other side of the substrate opposite to the EML chip, serving as electrical input and output interfaces of the double-ended EML COC component.

[0085] It should be noted that when the external PCBA or BOX housing uses a GSSG structure for electrical interface, the COC's electrical interface pins also adopt a GSSG structure to maintain synchronization. GSSG-type COC components are similar to GSGSG-type components, differing in that the central GND pin pad 312-2 is removed from the COC's input and output pin pads. However, the common GND (second common ground area 302-2) remains within the COC assembly body. Due to the reduction of GND pin pad 312-2, the signal line gaps (310, 311-1, 311-2) and high-frequency signal line output pin pads (313, 314) are adjusted accordingly to meet characteristic impedance requirements.

[0086] As shown in Figure 10, it includes an EML chip 101, a ceramic substrate 901 and a filter capacitor 103. In order to facilitate comparison with the GSGSG type (Example 1), the parts of the same structure of the two COC components are coded with the same number. A gold-tin eutectic area 301 and a common GND 1001-1 are set on the upper surface of the ceramic substrate 901. The EML chip 101 is set directly above the gold-tin eutectic area 301 and is fixed by gold-tin eutectic welding, and the front light-emitting surface 203 of the EML chip 101 faces the left side of the ceramic substrate 102. The filter capacitor 103 is set on the upper surface of the common GND 1001-1 and the area directly below as shown in Figure 10, and is spaced a certain distance from the gold-tin eutectic area 301. The filter capacitor 103 is fixed by gold-tin eutectic welding or conductive adhesive bonding. If necessary, an MPD backlight chip (not shown) is arranged on the right side of the rear light emitting surface 204 of the EML chip 101 and on the upper surface of the common GND 1001 - 1 and fixed by gold-tin eutectic soldering or conductive adhesive bonding.

[0087] As shown in FIG11 , the ceramic substrate 901 includes a gold-tin eutectic region 301, common GNDs (1001-1, 1001-2, 1001-3), a high-frequency positive signal line 303, a high-frequency negative signal line 304, a first matching resistor 305, a second matching resistor 306, high-frequency pin pads 307 and 308, a laser pin pad 309, signal line gaps 310, 311-1, and 311-2, output GND pin pads (1002-1 and 1002-2), high-frequency signal line output pin pads 1003 and 1004, a via 315, and a substrate 316. Common GND 1001-1, common GND 1001-2, and common GND 1001-3 are interconnected regions.

[0088] As shown in FIG11 , the X direction in FIG11 is the first direction, and the Y direction is the second direction. When viewed from top to bottom along the second direction, the following are, in order: common GND 1001-3, second signal line slot 311-1, high-frequency negative signal line 304 and second matching resistor 306, third signal line slot 311-2, common GND 1001-2, first signal line slot 310, high-frequency positive signal line 303, common GND 1001-1, laser pin pad 309, first matching resistor 305, and high-frequency pin pad 307. Common GND 1001 is located in the outer edge area, semi-enclosing the signal line slot 311-1, high-frequency negative signal line 304, second matching resistor 306, signal line slot 311-2, signal line slot 310, and high-frequency positive signal line 303. The AuSn eutectic region 301 is provided on the upper surface of the common GND 1001 - 1 and is higher than the common GND 1001 - 1 .

[0089] Specifically, the common GND (1001-1, 1001-2, 1001-3), high-frequency positive signal line 303, high-frequency negative signal line 304, first matching resistor 305, second matching resistor 306, high-frequency pin pads (307, 308), laser pin pad 309, signal line slots (310, 311-1, 311-2), output GND pin pads (1002-1, 1002-2), and high-frequency signal line output pin pads (1003, 1004) are all located in the same plane and are all located on the upper surface of substrate 316. They are all made of the same film material, such as Ti / PT / Au, with a thickness of microns, and the only difference is the pattern size. The via 315 is filled with conductive material, including but not limited to copper, silver, tungsten, etc., for connecting the common GND 1001 and the intermediate reference GND 401, and passes through the first ceramic layer 316-1 of the substrate (as shown in Figure 4).

[0090] Exemplarily, both the high-frequency positive signal line 303 and the high-frequency negative signal line 304 employ a linear pattern. The high-frequency positive signal line 303 comprises a high-frequency pin pad 308, a linear waveguide, and a high-frequency signal line output pin pad 1004. The high-frequency pin pad 308 is located on the left side, near the gold-tin eutectic region 301. The high-frequency negative signal line 304 comprises a linear waveguide and a high-frequency signal line output pin pad 1003. A second matching resistor 306 is provided on the left side of the high-frequency negative signal line 304. Between the common GND 1001-2 and the common GND 1001-3 are signal line gaps (311-1, 311-2), the high-frequency negative signal line 304, and the second matching resistor 306. The signal line gaps (311-1, 311-2) further surround the high-frequency negative signal line 304 and the second matching resistor 306. Between common GND 1001-1 and common GND 1001-2 is a signal line gap 310 and a high-frequency positive signal line 303. The output GND pin pads (1002-1, 1002-2), high-frequency signal line output pin pads (1003, 1004), and laser pin pads 309 are all located on the right side of the substrate, serving as the electrical input and output interfaces of the COC assembly. The width of the output GND pin pads (1002-1, 1002-2) and high-frequency signal line output pin pads (1003, 1004) is greater than 150 μm, meeting the bonding requirements of two gold wires.

[0091] It should be noted that, with respect to the high-frequency characteristic impedance, the width W1 of the signal line slots 311-1 and 311-2, the width W2 of the high-frequency negative signal line 304, the thickness T and dielectric constant of the substrate, the intermediate reference GND, and the common GND together form a single-ended coplanar waveguide structure, resulting in the required characteristic impedance, typically 50 ohms. Similarly, the width W3 of the signal line slot 310, the width W2 of the high-frequency positive signal line 303, the thickness T and dielectric constant of the substrate, the intermediate reference GND, and the common GND together form a single-ended coplanar waveguide structure, resulting in the required characteristic impedance, typically 50 ohms.

[0092] The characteristic impedance of the driver chip of the EML laser chip is 100 ohms. To match this, the first matching resistor 305 and the second matching resistor 306 each use a single-ended impedance of 50 ohms, forming a differential impedance of 100 ohms. In particular, the output GND pin pad 1002 and the high-frequency signal line output pin pads (1003, 1004) also meet the characteristic impedance requirements. Because the output GND pin pad 1002 and the high-frequency signal line output pin pads (1003, 1004) need to be made wider due to gold wire bonding, the gap of the signal line gap 311 is adjusted accordingly.

[0093] In order to reduce reflections, a trapezoidal structure with a gradually changing width is provided between the straight waveguide area of ​​the high-frequency positive signal line 303 and the high-frequency negative signal line 304 and the high-frequency signal line output pin pad (1003, 1004) for transition. The output GND pin pad 1002 and the high-frequency signal line output pin pad (1003, 1004) and the signal line gap 311 together constitute a differential coplanar waveguide structure. In addition, in order to ensure that the differential high-frequency signal transmission distance is similar, the length of the high-frequency positive signal line 303 and the high-frequency negative signal line 304 are substantially equal. In particular, in order to obtain good high-frequency characteristics, the size of the high-frequency pin pad 308 is increased to form an equivalent capacitor, and the equivalent inductance and equivalent resistance of the gold wire of the EML chip are added to form an RLC circuit to reduce the loss of high-frequency signals.

[0094] Correspondingly, the COC component is electrically interconnected with the electrical interface pins in the PCBA or BOX shell of the optical module, as shown in Figure 12. External electrical interface pin pads 1101-1105 are set on the right side of the EML COC component. The input and output pins 309, 1002-1, 1002-2, 1003 and 1004 of the COC are electrically interconnected with the electrical interface pin pads 1101-1105 through gold wires 1106-1110, one to one. The corresponding relationship is: the output GND pin pad 1002-1, the gold wire 1106 and the electrical interface GND pin pad 1101 are a group; high The high-frequency signal line output pin pad 1003, gold wire 1107, and electrical interface differential negative pin pad 1102 form a group; the high-frequency signal line output pin pad 1004, gold wire 1108, and electrical interface differential positive pin pad 1103 form a group; the output GND pin pad 1002-2, gold wire 1109, and electrical interface GND pin pad 1104 form a group; and the laser pin pad 309, gold wire 1110, and electrical interface laser pin pad 1105 form a group. Specifically, gold wires 1106-1109 are dual-wire, while gold wire 1110 is a single-wire.

[0095] It should be noted that the COC component itself has gold wire interconnection, which is the same as the above-mentioned GSGSG type (Example 1) and will not be repeated here.

[0096] The equivalent circuit of Figure 12 is shown in Figure 13. Referring to Figure 13, the EML chip 101 is equivalent to an EAM 601 and a DFB 602. Both EAM 601 and DFB 602 are connected to GND. A first matching resistor 305 is connected in parallel to the EAM 601. A second matching resistor 306 is connected in series between the high-frequency positive signal line 304 and the common GND 1001-3. A filter capacitor 103 is connected in parallel to the DFB 602.

[0097] Similarly, a modified structure exists: the high-frequency pin pad 307 is enlarged, for example, to a length of at least 0.45 mm, the first matching resistor 305 is shifted to the right, and a DC-block capacitor is surface-mounted on the high-frequency pin pad 307. This structure is identical to that shown in FIG7 of the first embodiment and will not be further described here.

[0098] It is understandable that the bandwidth simulation curve of the GSSG COC component and the external electrical interface (PCBA) is similar to FIG9 in the first embodiment, and will not be described again here.

[0099] In addition, for technical details not fully described in this GSSG type COC component embodiment, please refer to the GSGSG type COC component provided in the embodiment of the present invention as described above, and will not be repeated here.

[0100] It should be understood that the above is only an example and does not constitute any limitation to the technical solution of the present invention. In specific applications, those skilled in the art can make settings as needed, and the present invention does not impose any limitation on this.

[0101] It should be noted that the workflow described above is merely illustrative and does not limit the scope of protection of the present invention. In practical applications, technicians in this field can select part or all of it according to actual needs to achieve the purpose of the embodiment scheme, and no limitation is made here.

[0102] In addition, it should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or system comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or system. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or system comprising the element.

[0103] The serial numbers of the above embodiments of the present invention are for description only and do not represent the advantages or disadvantages of the embodiments.

[0104] Through the description of the above embodiments, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus the necessary general hardware platform, or of course by hardware, but in many cases the former is a better embodiment. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. The computer software product is stored in a storage medium (such as a read-only memory (ROM) / RAM, a magnetic disk, or an optical disk), and includes a number of instructions for enabling a terminal device (which can be a mobile phone, a computer, a server, or a network device, etc.) to execute the methods described in each embodiment of the present invention.

[0105] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A double-ended EML COC component, characterized in that: The double-ended EML COC component comprises: A ceramic substrate, on which a gold-tin eutectic region, a first common ground region, a second common ground region, a third common ground region, a first signal line, a second signal line, a first matching resistor, a second matching resistor, a high-frequency pin pad, a laser pin pad, a first signal line gap, a second signal line gap, a third signal line gap, an output ground pin plate, a high-frequency signal line output pin plate, a via and a substrate are provided; wherein the first common ground region, the second common ground region and the third common ground region are interconnected regions; the first signal line and the second signal line are designed in parallel, and each signal line includes one high-frequency signal line output pin plate; An EML chip is located directly above the AuSn eutectic region; A filter capacitor is located in the first common grounding region, and there is a gap between the filter capacitor and the gold-tin eutectic region.

2. The double-ended EML COC assembly according to claim 1, characterized in that: The first signal line and the second signal line both adopt a straight line pattern, and the signal paths of the first signal line and the second signal line extend along a first direction; Along a second direction perpendicular to the first direction, the third common ground area, the second signal line gap, the second signal line, the second matching resistor, the third signal line gap, the second common ground area, the first signal line gap, the first signal line, the first common ground area, the laser pin pad, the first matching resistor and the high-frequency pin pad are arranged in sequence.

3. The double-ended EML COC assembly according to claim 2, characterized in that: The EML chip comprises a high-frequency pin pad, a laser pad, a first light-emitting surface and a second light-emitting surface; the EML chip is provided with adjacent EAM areas and DFB areas; wherein, The EAM region and the DFB region are arranged sequentially along the first direction; The high-frequency pin pad and the first light-emitting surface are located in the EAM region, and the laser pad and the second light-emitting surface are located in the DFB region.

4. The double-ended EML COC assembly according to claim 1, characterized in that: The output ground pin plate includes a first output GND pin plate, a second output GND pin plate and a third output GND pin plate; wherein, The first output GND pin plate, the second output GND pin plate, the third output GND pin plate The foot plate, the high-frequency signal line output pin plate and the laser pin pad are all located on the other side of the substrate opposite to the EML chip, serving as electrical input and output interfaces of the double-ended EML COC component.

5. The double-ended EML COC assembly according to claim 4, characterized in that: The first common grounding area, the second common grounding area and the third common grounding area are located in the outer edge area, and surround the second signal line gap, the second signal line, the second matching resistor, the third signal line gap, the first signal line gap and the first signal line in a semi-enclosed manner; The gold-tin eutectic region is arranged on the upper surface of the first common grounding region and is higher than the first common grounding region; The first common ground area, the second common ground area, the third common ground area, the first signal line, the second signal line, the first matching resistor, the second matching resistor, the high-frequency pin pad, the laser pin pad, the first signal line gap, the second signal line gap, the third signal line gap, the first output GND pin pad, the second output GND pin pad, the third output GND pin pad and the high-frequency signal line output pin pad are all located in the same plane and are all located on the upper surface of the substrate.

6. The double-ended EML COC assembly according to claim 5, characterized in that: The slit width of the second signal line, the slit width of the third signal line, the line width of the second signal line, the thickness and dielectric constant of the substrate, the intermediate reference ground and the common ground constitute a first single-ended coplanar waveguide structure to form a first characteristic impedance, and the first characteristic impedance is 50 ohms; The slit width of the first signal line, the line width of the first signal line, the thickness and dielectric constant of the substrate, the intermediate reference ground and the common ground constitute a second single-ended coplanar waveguide structure to form a second characteristic impedance, and the second characteristic impedance is 50 ohms.

7. The double-ended EML COC assembly according to claim 6, characterized in that: The characteristic impedance of the driving chip of the EML chip is 100 ohms, and the first matching resistor and the second matching resistor respectively use a single-ended impedance of 50 ohms and form a differential of 100 ohms.

8. The double-ended EML COC assembly according to claim 1, characterized in that: The output ground pin plate includes a fourth output GND pin plate and a fifth output GND pin plate; wherein, The fourth output GND pin pad, the fifth output GND pin pad, the high-frequency signal line output pin pad and the laser pin pad are all located on the other side of the substrate opposite to the EML chip, serving as electrical input and output interfaces of the double-ended EML COC component.

9. The double-ended EML COC assembly according to claim 8, characterized in that: The first common grounding area, the second common grounding area and the third common grounding area are located in the outer edge area, and surround the second signal line gap, the second signal line, the second matching resistor, the third signal line gap, the first signal line gap and the first signal line in a semi-enclosed manner; The gold-tin eutectic region is arranged on the upper surface of the first common grounding region and is higher than the first common grounding region; The first common ground area, the second common ground area, the third common ground area, the first signal line, the second signal line, the first matching resistor, the second matching resistor, the high-frequency pin pad, the laser pin pad, the first signal line gap, the second signal line gap, the third signal line gap, the fourth output GND pin pad, the fifth output GND pin pad and the high-frequency signal line output pin pad are all located in the same plane and are all located on the upper surface of the substrate.

10. The double-ended EML COC assembly according to claim 9, characterized in that: The fourth output GND pin pad and the fifth output GND pin pad, the high-frequency signal line output pin pad, and the second signal line slot and the third signal line slot together constitute a differential coplanar waveguide structure.

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