Packaging structure of coplanar electrode photoconductive switch

Abstract

This invention provides a packaging structure for a photoconductive switch with in-plane electrodes, including a packaging shell, an output connector, and a power supply connector. The packaging shell contains a packaging chamber, within which the photoconductive switch is disposed. The packaging chamber is filled with transparent insulating oil, which surrounds the photoconductive switch. A first light window is located on the top of the packaging shell, corresponding vertically to the light-transmitting trigger area on the front of the photoconductive switch. The output connector penetrates one side wall of the packaging shell and connects the first electrode of the photoconductive switch to an external circuit. The power supply connector penetrates the other side wall of the packaging shell and connects the second electrode of the photoconductive switch to a power supply line. The packaging structure of the photoconductive switch with in-plane electrodes provided by this invention, by encapsulating the photoconductive switch in the packaging shell and encapsulating the photoconductive switch chip with transparent insulating oil, effectively improves the device's withstand voltage capability, reduces optical loss, and ensures efficient utilization of the trigger light.

Description

Technical Field

[0001] This invention belongs to the field of photoconductive semiconductor device technology, and specifically relates to a packaging structure of a photoconductive switch with coplanar electrodes. Background Technology

[0002] As a core semiconductor device that realizes electrical signal control based on the photoelectric effect, photoconductive switches have become key supporting devices in high-end electronic fields such as high-voltage pulse power systems due to their excellent characteristics such as high power density, ultra-fast response speed, low trigger jitter and strong anti-electromagnetic interference capability.

[0003] Currently, photoconductive switches based on wide-bandgap semiconductor materials such as gallium nitride and silicon carbide can achieve high breakdown voltage and good high-temperature operating stability by leveraging the inherent wide bandgap characteristics of these materials. These devices are mainly divided into bulk electrode structures (such as opposite or obliquely opposite structures) and on-plane electrode structures based on differences in electrode structure. While bulk electrode structures possess high withstand voltage, their photogenerated carrier generation region is located inside the material, resulting in lower photoelectric conversion efficiency and requiring higher trigger light energy. On-plane electrode structures, by fabricating both electrodes on the same surface of the semiconductor material, significantly improves light energy utilization compared to bulk electrode structures and effectively reduces the trigger light energy requirement.

[0004] However, for in-plane electrode structures, electric field concentration easily occurs on the electrode gap surface when subjected to high voltage, leading to surface flashover or breakdown, which severely restricts the operating voltage of the device. In the prior art, to alleviate surface flashover and improve the device's withstand voltage, insulating adhesive is usually used to cover the surface electrodes and light-transmitting area. However, the insulating adhesive will significantly absorb the trigger light, reducing the effective incident light energy, and thus seriously affecting the device's conduction response characteristics. Summary of the Invention

[0005] The packaging structure of the photoconductive switch with coplanar electrodes provided in this invention can solve the technical problems of insufficient high-voltage working capability and low light energy utilization of photoconductive switches with coplanar electrode structures in the prior art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: to provide a packaging structure for a photoconductive switch with in-plane electrodes, comprising: The encapsulation housing has an internal encapsulation chamber, in which a photoconductive switch is disposed. The encapsulation chamber is filled with transparent insulating oil, which surrounds the photoconductive switch. The top of the encapsulation housing has a first light window, which corresponds vertically to the light-transmitting trigger area on the front of the photoconductive switch. An output connector, disposed through one side wall of the encapsulation housing, is used to connect the first electrode of the photoconductive switch to an external circuit; and A power supply connector is provided through the other side wall of the encapsulation housing and is used to connect the second electrode of the photoconductive switch to the power supply line.

[0007] In one possible implementation, a connecting groove is provided on the bottom wall of the encapsulation chamber, and the connecting groove communicates with the encapsulation chamber; the two sides of the opening of the connecting groove are respectively used to support the two ends of the photoconductive switch, and the connecting groove is filled with the transparent insulating oil so that the transparent insulating oil covers the bottom of the photoconductive switch.

[0008] In some embodiments, a second light window is provided at the bottom of the encapsulation housing, the second light window being vertically corresponding to the communicating groove, and the second light window being used to guide trigger light from the back of the photoconductive switch to illuminate the light-transmitting trigger area.

[0009] In one possible implementation, one side wall of the encapsulation housing is provided with a first groove with an outward opening, and the inner wall of the first groove is provided with a connection hole communicating with the encapsulation chamber. The output connector is an output insulator. The inner end of the pin of the output insulator is connected to the first electrode, and the outer end of the pin of the output insulator is connected to an external circuit through an RF connector. The connection end of the RF connector is connected to the connection hole. The first groove is used to fill insulating sealant.

[0010] In some embodiments, a second groove with an outward opening is provided on the other side wall of the packaging housing, and the second groove is disposed opposite to the first groove; The power supply connector is a power supply insulator, the inner end of the needle of the power supply insulator is connected to the second electrode, and the outer end of the needle of the power supply insulator is connected to the power supply line; The distance between the needle of the power supply insulator and the sidewall of the second groove is not less than 3mm, and the second groove is used to fill insulating sealant.

[0011] In some embodiments, the distance from the vertical centerline of the connecting groove to the inner wall of the first groove is less than the distance from the vertical centerline of the connecting groove to the inner wall of the second groove, so that the first electrode is close to the output insulator; The bottom wall of the encapsulation chamber is provided with an upward-opening isolation groove. The isolation groove is located near the side wall of the encapsulation chamber adjacent to the second groove, and the isolation groove corresponds vertically to the pin of the power supply insulator.

[0012] In some embodiments, the bottom wall of the encapsulation chamber is provided with an upward-opening first transition groove, which communicates with the connecting groove.

[0013] In some embodiments, the bottom wall of the encapsulation chamber is further provided with an upward-opening second transition groove, which communicates with the connecting groove; the second transition groove and the first transition groove both extend to the same side of the connecting groove, and the extension length of the second transition groove is greater than the extension length of the first transition groove.

[0014] In some embodiments, the encapsulation housing includes a base and a cover plate, the cover plate being fastened to the top of the base, and the encapsulation chamber being formed between the cover plate and the base; the first light window is disposed on the cover plate, and the second light window is disposed on the bottom wall of the base; The top surface of the base is provided with a circumferentially extending sealing groove, which is located on the outer periphery of the encapsulation chamber. A sealing ring is embedded in the sealing groove. The bottom surface of the cover plate is provided with a pressing boss, which is inserted into the sealing groove and the bottom surface of the pressing boss abuts against the sealing ring.

[0015] In some embodiments, the top surface of the glass of the first light window is lower than the top surface of the cover plate; the bottom surface of the glass of the second light window is higher than the bottom surface of the base.

[0016] The beneficial effects of the packaging structure of the same-surface electrode photoconductive switch provided by the present invention are as follows: Compared with the prior art, the packaging structure of the same-surface electrode photoconductive switch of the present invention encapsulates the photoconductive switch in the packaging cavity through the packaging shell, and fills the packaging cavity with transparent insulating oil, so that the transparent insulating oil encapsulates the photoconductive switch chip. By utilizing the high insulation strength characteristics of the transparent insulating oil, the path of flashover breakdown between electrodes and on the chip surface along the air medium is completely eliminated, thereby effectively improving the high voltage working capability.

[0017] Meanwhile, the transparent insulating oil has high transmittance for trigger light. After the trigger light passes through the first light window on the package housing and the transparent insulating oil in the package cavity, it can directly reach the light-transmitting trigger area on the front of the photoconductive switch with extremely low loss. This solves the problem of significant absorption of trigger light by traditional insulating glue. While achieving high-voltage insulation, it minimizes optical loss and ensures efficient utilization of trigger light.

[0018] Moreover, transparent insulating oil can also serve as a thermally conductive medium, which can more evenly conduct the heat generated by the photoconductive switch chip during operation to the package housing, helping to reduce the chip junction temperature and improve the power handling capacity and lifespan of the device. At the same time, the transparent insulating oil environment effectively isolates external moisture, dust and other contaminants, enhancing the long-term environmental stability and operational reliability of the device.

[0019] Furthermore, the two electrodes of the photoconductive switch are led out to the outside of the package housing via output connectors and power supply connectors, facilitating electrical connection with high-voltage pulse power systems. The structure is simple and reliable. This embodiment provides a compact, robust, and easily integrated package structure for the photoconductive switch chip, the high-insulation medium (transparent insulating oil), and the optical interface (first optical window), significantly simplifying the assembly process and greatly improving assembly efficiency. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of a photoconductive switch with a coplanar electrode structure in the prior art; Figure 2 A schematic diagram of the packaging structure of the same-plane electrode photoconductive switch provided in an embodiment of the present invention (cover plate open). Figure 3 This is an embodiment of the present invention. Figure 2 Schematic diagram of the cross-sectional structure along line AA (cover plate in the fastened state); Figure 4 This is an embodiment of the present invention. Figure 3 A schematic diagram of another embodiment; Figure 5 This is a schematic diagram of the encapsulation structure of the same-surface electrode photoconductive switch provided in an embodiment of the present invention, after the cover plate is hidden. Figure 6 This is an embodiment of the present invention. Figure 5 A structural diagram from another perspective; Figure 7 This is an embodiment of the present invention. Figure 5 A structural diagram viewed from below; Figure 8 This is a schematic diagram of the cover plate and the first light window provided in an embodiment of the present invention.

[0022] The following are the labeling elements in the figure: 1. Encapsulation housing; 11. Base; 111. Encapsulation chamber; 112. Communicating groove; 113. Second light window; 114. Isolation groove; 115. First transition groove; 116. Second transition groove; 117. Sealing groove; 12. Cover plate; 121. First light window; 122. Pressing boss; 13. First groove; 131. Connecting hole; 14. Second groove; 2. Output connector; 21. Output insulator; 3. Power supply connector; 31. Power supply insulator; 4. Sealing ring; 10. Photoconductive switch; 101. First electrode; 102. Second electrode; 103. Light-transmitting trigger area. Detailed Implementation

[0023] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0024] It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or indirectly on the other element. It should be understood that the terms "length," "width," "upper," "lower," "front," "rear," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention.

[0025] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0026] In addition, in the embodiments of this application, "inner" refers to the side facing the encapsulation chamber 111, and "outer" refers to the side away from the encapsulation chamber 111.

[0027] Please refer to the following: Figures 1 to 8The packaging structure of the same-surface electrode photoconductive switch provided by the present invention will now be described. The packaging structure of the same-surface electrode photoconductive switch includes a packaging shell 1, an output connector 2, and a power supply connector 3. The packaging shell 1 has a packaging chamber 111 inside, and the photoconductive switch 10 is disposed in the packaging chamber 111. The packaging chamber 111 is filled with transparent insulating oil, which surrounds the photoconductive switch 10. The top of the packaging shell 1 has a first light window 121, which corresponds vertically to the light-transmitting trigger area 103 on the front of the photoconductive switch 10. The output connector 2 is disposed through one side wall of the packaging shell 1 and is used to connect the first electrode 101 of the photoconductive switch 10 to an external circuit. The power supply connector 3 is disposed through the other side wall of the packaging shell 1 and is used to connect the second electrode 102 of the photoconductive switch 10 to a power supply line.

[0028] The packaging structure of the same-surface electrode photoconductive switch provided in this embodiment has the following advantages compared with the prior art: First, the photoconductive switch 10 is encapsulated in the encapsulation chamber 111 through the encapsulation housing 1, and the encapsulation chamber 111 is filled with transparent insulating oil, so that the transparent insulating oil encapsulates the photoconductive switch 10 chip. By utilizing the high insulation strength characteristics of the transparent insulating oil, the path of flashover breakdown between electrodes and on the chip surface along the air medium is completely eliminated, thereby effectively improving the high voltage working capability.

[0029] Secondly, the transparent insulating oil has high transmittance for trigger light. After the trigger light passes through the first light window 121 on the encapsulation housing 1 and the transparent insulating oil in the encapsulation chamber 111, it can directly reach the light-transmitting trigger area 103 on the front of the photoconductive switch 10 with extremely low loss. This solves the problem of significant absorption of trigger light by traditional insulating glue. While achieving high voltage insulation, it minimizes optical loss and ensures efficient utilization of trigger light.

[0030] Third, the transparent insulating oil can also serve as a heat-conducting medium, which can more evenly conduct the heat generated by the photoconductive switch 10 chip to the package housing 1, helping to reduce the chip junction temperature and improve the power handling capacity and lifespan of the device. At the same time, the transparent insulating oil environment effectively isolates external moisture, dust and other pollutants, enhancing the long-term environmental stability and operational reliability of the device.

[0031] Fourth, the two electrodes of the photoconductive switch 10 are led out to the outside of the package housing 1 through the output connector 2 and the power supply connector 3, which facilitates electrical connection with the high-voltage pulse power system, resulting in a simple and reliable structure. This embodiment provides a compact, robust, and easily integrated package structure for the photoconductive switch 10 chip, the high-insulation medium (transparent insulating oil), and the optical interface (first optical window 121), greatly simplifying the assembly process and significantly improving assembly efficiency.

[0032] Understandably, the photoconductive switch 10 is made of a wide-bandgap semiconductor material (such as gallium nitride or silicon carbide), see [link to relevant documentation]. Figure 1 The front side of the photoconductive switch 10 chip (i.e. Figure 3 The upper surface of the photoconductive switch 10 is provided with a first electrode 101 and a second electrode 102 spaced apart, and the exposed semiconductor area between the two electrodes is the light-transmitting trigger area 103. When a laser of a specific wavelength irradiates the light-transmitting trigger area 103, the semiconductor material absorbs photons to generate electron-hole pairs, thereby forming a conductive channel between the two electrodes and realizing the rapid conduction of the device.

[0033] It should be noted that this embodiment preferably uses a 355nm ultraviolet pulsed laser as the trigger light. Compared with the 532nm laser used in the traditional photoconductive switch 10, the 355nm laser can more effectively excite the intrinsic photoconductive effect. At the same time, the absorption depth of the 355nm laser in the aforementioned semiconductor material is highly matched with the effective working area of ​​the coplanar electrode structure, which can achieve higher bulk absorption efficiency and more concentrated carrier generation, thereby obtaining better conduction characteristics per unit light energy, i.e., higher light energy utilization.

[0034] The first optical window 121 is sealed and installed in the through-hole at the top of the package housing 1. The first optical window 121 is made of a material with high transmittance to 355nm trigger light, such as fused silica glass. The position of the first optical window 121 corresponds vertically to the light-transmitting trigger area 103 on the front of the photoconductive switch 10. To ensure that the first optical window 121 can be adapted to photoconductive switches 10 of different sizes, the area of ​​the first optical window 121 can be designed to match the light-transmitting trigger area 103 of the largest commonly used photoconductive switch 10. In the external optical path design, the spot size of the 355nm trigger light can be precisely adjusted by optical components such as focusing lens groups so that the spot of the trigger light can be effectively concentrated in the light-transmitting trigger area 103 after passing through the first optical window 121, ensuring efficient and concentrated use of light energy and avoiding stray light interference to electrodes or other areas.

[0035] Transparent insulating oils are selected from liquid media with high insulation strength, high light transmittance, and stable chemical properties, such as high-purity silicone oil or fluorinated liquids. On the one hand, the high breakdown field strength of transparent insulating oils provides high-voltage insulation, fundamentally suppressing the surface flashover problem that easily occurs in air. On the other hand, transparent insulating oils have extremely low absorption of 355nm trigger light, resulting in minimal light loss during light transmission and significantly improving light energy utilization.

[0036] The enclosure 1 is made of metal, which not only has high mechanical strength, but also allows for convenient and reliable grounding, improving the safety of high-voltage operation. At the same time, it can effectively shield external electromagnetic interference, ensuring the accuracy and stability of high-voltage switch operation. Moreover, the high thermal conductivity of metal enables the enclosure 1 to play an excellent heat dissipation role, which helps maintain the stability of device performance.

[0037] Specifically, the encapsulation housing 1 has a rectangular structure with dimensions of 20mm × 30mm × 15mm. During use, a micro-assembly process is employed, improving reliability and consistency. Furthermore, the side wall of the encapsulation housing 1 is provided with threaded mounting holes, allowing for quick connection to the fixtures of the testing device via bolts, simplifying the assembly process for performance testing of the photoconductive switch 10.

[0038] In some embodiments, the photoconductive switch 10 chip can be supported and connected in the packaging chamber 111 by a fixed bracket, so that transparent insulating oil can wrap around the bottom of the photoconductive switch 10 to provide all-round protection for the photoconductive switch 10.

[0039] In the parallel embodiments, please refer to Figure 2 and Figure 3 The bottom wall of the encapsulation chamber 111 is provided with a connecting groove 112, which is connected to the encapsulation chamber 111. The two sides of the opening of the connecting groove 112 are respectively used to support the two ends of the photoconductive switch 10. The connecting groove 112 is filled with transparent insulating oil so that the transparent insulating oil covers the bottom of the photoconductive switch 10.

[0040] In this embodiment, the two electrodes of the photoconductive switch 10 are arranged along the width direction of the encapsulation housing 1, that is, the output connector 2 and the power supply connector 3 are arranged through the side wall of the encapsulation housing 1 along the width direction. In the width direction of the encapsulation housing 1, the two ends of the photoconductive switch 10 are respectively connected to the bottom wall of the encapsulation chamber 111 on both sides of the opening of the connecting groove 112, and are fixed by adhesive or snap-fit ​​connections to ensure that the photoconductive switch 10 is firmly installed and to prevent displacement when filling with transparent insulating oil. In the length direction of the encapsulation housing 1, the size of the connecting groove 112 can be larger than the size of the photoconductive switch 10 to facilitate communication between the connecting groove 112 and the encapsulation chamber 111. When filling the encapsulation chamber 111 with transparent insulating oil, the connecting groove 112 can also be filled simultaneously.

[0041] By providing a connecting groove 112 at the bottom of the photoconductive switch 10 and filling it with transparent insulating oil, the transparent insulating oil can fully cover the bottom of the photoconductive switch 10, promoting effective heat dissipation at the bottom of the photoconductive switch 10 and helping to enhance the power handling capacity and operational reliability of the device. At the same time, it achieves all-round oil immersion of the photoconductive switch 10, which can effectively eliminate tiny air gaps at the bottom of the photoconductive switch 10, eliminate weak points in insulation, and further improve the withstand voltage capability of the device. In addition, the connecting groove 112 filled with transparent insulating oil can also buffer thermal stress and provide damping protection, enhancing the structural stability of the device under temperature changes and mechanical vibration environments.

[0042] In some embodiments, see Figure 4 and Figure 7 The bottom of the housing 1 is provided with a second light window 113, which corresponds vertically to the connecting groove 112. The second light window 113 is used to guide the trigger light from the back of the photoconductive switch 10 (i.e., Figure 4 The lower surface of the light-conducting switch 10 is illuminated by the light-conducting trigger area 103.

[0043] A mounting hole is made at the bottom of the encapsulation housing 1 at the position corresponding to the connecting groove 112, and the mounting hole is connected to the connecting groove 112. The second light window 113 is sealed and embedded in the mounting hole to ensure that the second light window 113 can be vertically aligned with the connecting groove 112, and that the trigger light incident from the second light window 113 can be vertically aligned with the light-transmitting trigger area 103 from the back of the light guide switch 10.

[0044] The material of the second optical window 113 is the same as that of the first optical window 121. For example, using highly transparent fused silica glass can better adapt to 355nm wavelength lasers. Specifically, a sealing strip is provided between the second optical window 113 and the mounting hole, and the gaps around the two are filled with sealant to ensure the sealing of the encapsulation chamber 111 and prevent leakage of internal transparent insulating oil.

[0045] Considering that wide-bandgap semiconductor materials such as gallium nitride or silicon carbide have a low effective absorption depth for 355nm wavelength lasers, the thickness of the photoconductive switch 10 chip with the same electrode will cause differences in light source requirements and operating voltage withstand capability between back-illuminated and front-illuminated modes. In this embodiment, the cooperation of the first optical window 121 and the second optical window 113 can realize the switching between front-triggered and back-triggered modes. During triggering, the corresponding mode can be selected according to the working conditions. In front-triggered mode, the 355nm trigger light enters the light-transmitting trigger area 103 on the front of the photoconductive switch 10 through the first optical window 121, which is suitable for low-voltage, low-intensity, high-output triggering scenarios. In back-triggered mode, the 355nm laser enters from the second optical window 113, passes through the second optical window 113 and the transparent insulating oil in the connecting groove 112 in sequence, and accurately illuminates the light-transmitting trigger area 103 from the back of the photoconductive switch 10, which is suitable for high-voltage, high-intensity triggering test scenarios.

[0046] By adding a second optical window 113 corresponding to the connecting slot 112, not only is flexible switching between front and back trigger modes of the photoconductive switch 10 achieved, but it also adapts to different operating conditions. This effectively improves the high-voltage operating capability of the same-surface electrode structure while accommodating testing and verification as well as practical application scenarios, without requiring significant modifications to the original packaging structure. Specifically, front triggering can be used to test and verify the operating limits of the same-surface electrode structure photoconductive switch 10 under 355nm laser front triggering; back triggering is used to test and verify the high light energy utilization and voltage withstand capability of the photoconductive switch 10 made of thick material at the effective absorption depth of 355nm laser. In other words, this packaging structure can both complete the device performance limit calibration through front triggering and meet the usage requirements under high-voltage and high-intensity light conditions through back triggering.

[0047] Meanwhile, the combination of transparent insulating oil and the second light window 113 can effectively avoid energy loss of trigger light when triggered from the back, and will not damage the sealing and insulation protection effect of the encapsulation chamber 111, further expanding the applicable scenarios of the photoconductive switch 10 and improving its versatility and practicality.

[0048] In some embodiments, see Figure 3 , Figure 4 and Figure 7 The packaging housing 1 has a first groove 13 with an outward opening on one side wall. The inner wall of the first groove 13 has a connection hole 131 that communicates with the packaging chamber 111. The output connector 2 is an output insulator 21. The inner end of the pin of the output insulator 21 is connected to the first electrode 101. The outer end of the pin of the output insulator 21 is connected to the external circuit through an RF connector. The connection end of the RF connector is connected to the connection hole 131. The first groove 13 is used to fill the insulating sealant.

[0049] In this embodiment, an insulator structure is used as the output connector 2. It should be noted that the insulator structure is composed of a central metal needle and an outer ceramic insulator through a metallization sealing process, which has good insulation strength and airtightness.

[0050] Specifically, the outer peripheral insulator of the output insulator 21 is fixed on the inner groove wall of the first groove 13, and its inner end is located in the encapsulation chamber 111 and connected to the first electrode 101 of the photoconductive switch 10 through conductive adhesive or gold-plated tape; its outer end extends into the first groove 13 and is connected to the RF connector, while the connection end of the RF connector is threaded to the connection hole 131 to ensure reliable installation of the RF connector and the encapsulation housing 1.

[0051] It should be noted that the connection hole 131 can also serve as an injection port for transparent insulating adhesive. Specifically, during the actual assembly process, the photoconductive switch 10 is first fixed inside the encapsulation chamber 111 and electrically connected to the output insulator 21 and the power supply connector 3. Then, transparent insulating oil is injected through the connection hole 131 using a dedicated oiling device until the entire encapsulation chamber 111 is filled. Next, the RF connector is threaded into the connection hole 131, and simultaneously, the RF connector is inserted into the outer end of the pin of the output insulator 21 to achieve the electrical interface connection at the output end. Afterward, insulating sealant (such as high-temperature curing silicone rubber or epoxy resin) is filled into the surrounding gaps of the connection hole 131, while the first groove 13 is filled to be flush with the side wall of the encapsulation housing 1, leaving only the connection port of the RF connector exposed. After the insulating sealant cures, it not only reliably seals the connection hole 131 but also forms an additional insulating barrier.

[0052] In this embodiment, the output insulator 21 replaces the traditional lead wire structure, avoiding the problems of lead wire detachment and connection failure caused by external force; moreover, the output insulator 21 has a compact structure, and when integrated with a standard RF connector, it can form a continuous transmission channel with controllable impedance (such as 50Ω), minimizing signal reflection and waveform distortion, and ensuring high-fidelity output of high-voltage pulses.

[0053] Based on this, the connection hole 131 connected to the RF connector can also serve as an injection port for transparent insulating oil. After the connection is completed, the gaps in the connection hole 131 and the first groove 13 are filled with insulating sealant to form a reliable sealing structure, eliminating the risk of leakage of transparent insulating oil. At the same time, the cured insulating sealant filled in the first groove 13 significantly increases the surface creepage distance from the internal high voltage point to the external encapsulation housing 1, further improving the insulation safety of this critical interface area and ensuring the long-term high-voltage operation stability of the device.

[0054] In some embodiments, see Figure 3 , Figure 4 and Figure 5 The other side wall of the encapsulation housing 1 is provided with a second groove 14 with the opening facing outward. The second groove 14 is arranged opposite to the first groove 13. The power supply connector 3 is a power supply insulator 31. The inner end of the needle of the power supply insulator 31 is connected to the second electrode 102, and the outer end of the needle of the power supply insulator 31 is connected to the power supply line. The distance between the needle of the power supply insulator 31 and the groove side wall of the second groove 14 is not less than 3mm. The second groove 14 is used to fill the insulating sealant.

[0055] In this embodiment, the power supply connector 3 also adopts an insulator structure. Specifically, the outer peripheral insulator of the power supply insulator 31 is fixedly installed on the inner groove wall of the second groove 14. Its inner end of the needle is located in the encapsulation chamber 111 and is connected to the second electrode 102 of the photoconductive switch 10 through conductive glue or gold-plated tape. Its outer end of the needle extends to the outside of the encapsulation housing 1 for low-impedance connection to the external high-voltage power supply line.

[0056] It should be noted that after the power supply insulator 31 is installed, the minimum straight-line distance L between its pin and the metal groove sidewall of the second groove 14 is limited to not less than 3mm, such as 3.2mm, 3.3mm, or 3.5mm. Afterwards, insulating sealant is filled into the second groove 14. Once the sealant has cured, it completely covers and seals the installation area of ​​the power supply insulator 31, leaving only the outer end of the pin exposed for subsequent line connections.

[0057] By limiting the minimum distance between the power supply insulator 31 pin and the side wall of the second groove 14, the insulation distance between the power supply insulator 31 pin (at high potential) and ground (metallic encapsulation housing 1) is guaranteed, fundamentally preventing high voltage breakdown or surface discharge caused by insufficient insulation distance, and helping to improve the maximum operating voltage of the device.

[0058] Furthermore, by setting a second groove 14 and filling the second groove 14 with insulating sealant, the insulating sealant wraps around the outer periphery of the power supply insulator 31 pin, effectively extending the surface creepage distance, further improving the ultimate operating voltage that the power supply port can withstand, and realizing the overall ultra-high withstand voltage capability of the device.

[0059] In some embodiments, see Figure 3 , Figure 4 and Figure 6 The distance d1 from the vertical center line of the connecting groove 112 to the inner wall of the first groove 13 is less than the distance d2 from the vertical center line of the connecting groove 112 to the inner wall of the second groove 14, so that the first electrode 101 is close to the output insulator 21; the bottom wall of the encapsulation chamber 111 is provided with an upward-opening isolation groove 114, which is located near the side wall of the encapsulation chamber 111 adjacent to the second groove 14, and the isolation groove 114 corresponds vertically to the pin of the power supply insulator 31.

[0060] In this embodiment, the distance between the inner wall of the first groove 13 and the corresponding side wall of the encapsulation chamber 111 is equal to the distance between the inner wall of the second groove 14 and the corresponding side wall of the encapsulation chamber 111. Based on this, the distance d1 is made smaller than the distance d2, which means that the connecting groove 112 is not centered on the bottom wall of the encapsulation chamber 111, but is set close to the side of the first groove 13.

[0061] For the output end of the package structure, the connecting groove 112 is set on the side close to the first groove 13. When installing the photoconductive switch 10, in order to ensure that the light-transmitting trigger area 103 of the photoconductive switch 10 can correspond vertically with the connecting groove 112, the photoconductive switch 10 also needs to be moved closer to the first groove 13. This makes the first electrode 101 on the photoconductive switch 10 closer to the output insulator 21 installed in the area of ​​the first groove 13. Correspondingly, the extension length of the inner end of the pin of the output insulator 21 in the package cavity 111 is shortened.

[0062] It is understandable that in high-speed pulse circuits, any section of wire or conductor will introduce parasitic inductance proportional to its length. This parasitic inductance severely hinders rapid changes in current, causing a slower pulse rise edge, generating a back electromotive force, or even oscillation. This embodiment optimizes the spatial layout by changing the position of the connecting slot 112, forcing the photoconductive switch 10 closer to the output end. This effectively reduces the length of the pin in the output insulator 21, thereby significantly reducing the parasitic inductance of the output circuit and optimizing the fast response characteristics of the photoconductive switch 10.

[0063] For the power supply end of the package structure, the isolation groove 114 is disposed near the side wall adjacent to the second groove 14 of the package chamber 111, and the isolation groove 114 is located below the pin of the power supply insulator 31. The arrangement of the isolation groove 114 is equivalent to making the bottom wall of the package chamber 111 corresponding to the bottom of the pin of the power supply insulator 31 recessed downward, so that the pin of the power supply insulator 31 and the bottom wall of the package chamber 111 in the vertical direction are provided by the groove depth of the isolation groove 114.

[0064] In this embodiment, the encapsulation housing 1 is a metal housing that can be directly used for grounding. The isolation groove 114 added to the bottom wall of the encapsulation chamber 111 effectively increases the spatial distance between the power supply insulator 31 pin and the nearest grounded metal surface, which significantly increases the shortest breakdown path length at that point, improves the insulation strength of the power supply terminal to ground (encapsulation housing 1), and further ensures the overall withstand voltage capability of the device.

[0065] In some embodiments, see Figure 6 The bottom wall of the encapsulation chamber 111 is provided with an upward-opening first transition groove 115, which is connected to the connecting groove 112.

[0066] Before filling with transparent insulating oil, the photoconductive switch 10 needs to be fixed, usually by using adhesive to bond it to the bottom wall of the encapsulation chamber 111. Along the length of the encapsulation housing 1, when the size of the connecting groove 112 is larger than the chip size of the photoconductive switch 10, the transparent insulating oil can be simultaneously filled into the connecting groove 112 through the portion extending beyond the chip of the photoconductive switch 10. As the size of the photoconductive switch 10 increases, it will cover the connecting groove 112 after being bonded and fixed. At this time, transparent insulating oil can be simultaneously filled into the connecting groove 112 through the first transition groove 115, ensuring complete filling of the transparent insulating oil and guaranteeing the insulation withstand voltage and heat dissipation performance of the device.

[0067] Specifically, the first transition groove 115 is an elongated groove located on one side of the connecting groove 112 and extending along the length of the encapsulation housing 1. Its depth is relatively shallow, just enough to allow the transparent insulating oil to flow. Two first transition grooves 115 can be provided, extending to both sides of the connecting groove 112 respectively, to increase the filling speed of the transparent insulating oil.

[0068] In some embodiments, see Figure 6 The bottom wall of the encapsulation chamber 111 is also provided with a second transition groove 116 with an upward opening. The second transition groove 116 is connected to the connecting groove 112. The second transition groove 116 and the first transition groove 115 both extend to the same side of the connecting groove 112, and the extension length of the second transition groove 116 is greater than the extension length of the first transition groove 115.

[0069] As the size of the photoconductive switch 10 chip increases further, its edge may completely cover the first transition groove 115, thus blocking it after it is bonded and fixed around the photoconductive switch 10. At this time, since the extension length of the second transition groove 116 is greater than that of the first transition groove 115, the second transition groove 116 can serve as a filling inlet further away from the connecting groove 112, ensuring that the connecting groove 112 can still maintain communication with the encapsulation chamber 111, and the transparent insulating oil synchronously fills the connecting groove 112 through the second transition groove 116.

[0070] The combined design of the first transition groove 115 and the second transition groove 116 ensures that the same package housing 1 can reliably adapt to a variety of different specifications of photoconductive switch 10 chips without having to produce a new package housing 1 for each chip size, thus improving the compatibility of the package housing 1.

[0071] The effective filling of the connecting groove 112 with transparent insulating oil not only improves the withstand voltage and heat dissipation performance of the photoconductive switch 10, but also effectively reduces the light energy loss of the trigger light and improves the light energy utilization rate when the back is triggered, in the embodiment where back illumination is performed through the second light window 113.

[0072] In some embodiments, see Figure 2 , Figure 4 and Figure 8 The encapsulation housing 1 includes a base 11 and a cover plate 12. The cover plate 12 is fastened to the top of the base 11, and an encapsulation chamber 111 is formed between the cover plate 12 and the base 11. A first light window 121 is provided on the cover plate 12, and a second light window 113 is provided on the bottom wall of the base 11. A circumferentially extending sealing groove 117 is provided on the top surface of the base 11. The sealing groove 117 is located on the outer periphery of the encapsulation chamber 111, and a sealing ring 4 is embedded in the sealing groove 117. A pressing boss 122 is provided on the bottom surface of the cover plate 12. The pressing boss 122 is inserted into the sealing groove 117, and the bottom surface of the pressing boss 122 abuts against the sealing ring 4.

[0073] In this embodiment, the encapsulation housing 1 is designed as a separate structure of base 11 and cover plate 12, so that the fixed installation of the photoconductive switch 10 and its electrical connection with the output connector 2 and the power supply connector 3 can be completed on the open, visible and easy-to-operate base 11 before the cover plate 12 is fastened, which greatly reduces the process difficulty and improves the assembly efficiency and accuracy.

[0074] When the cover plate 12 is fastened, the pressing boss 122 is precisely inserted into the sealing groove 117 and pressed down on the cover plate 12, so that the bottom surface of the pressing boss 122 tightly abuts against and compresses the sealing ring 4 in the sealing groove 117, thereby forming a continuous and reliable annular sealing barrier at the connection interface between the base 11 and the cover plate 12, ensuring the sealing of the encapsulation chamber 111 and preventing leakage of transparent insulating oil or intrusion of external contaminants.

[0075] In some embodiments, see Figure 2 , Figure 4 and Figure 7 The top surface of the glass of the first light window 121 is lower than the top surface of the cover plate 12; the bottom surface of the glass of the second light window 113 is higher than the bottom surface of the base 11.

[0076] The installation of the first light window 121 can be achieved by setting a stepped hole in the cover plate 12. Specifically, a first hole is set on the top surface of the cover plate 12, and a second hole coaxial with the first hole is set on the bottom surface of the cover plate 12. The area of ​​the second hole is larger than the area of ​​the first hole, so that the first hole and the second hole are connected to form a stepped hole that penetrates the thickness of the cover plate 12. The glass sheet for making the first light window 121 can be fixed to the top wall of the second hole by adhesive bonding. At this time, the distance from the top surface of the glass of the first light window 121 to the top surface of the cover plate 12 is the depth of the first hole. The first hole, the second hole, and the glass of the first light window 121 can all be circular or rectangular.

[0077] For the installation of the second light window 113, a countersunk installation can be adopted. Specifically, a countersunk hole is processed on the bottom surface of the base 11. The countersunk hole is connected to the connecting groove 112, and the depth of the countersunk hole is greater than the thickness of the glass sheet of the second light window 113. After the glass sheet of the second light window 113 is embedded in the top wall of the countersunk hole, the bottom surface of the glass of the second light window 113 can be higher than the bottom surface of the base 11.

[0078] The installation method of this embodiment embeds the fragile light window glass inside the outer surface of the metal encapsulation housing 1, thereby providing direct and effective mechanical protection for the first light window 121 and the second light window 113, reducing the risk of scratches and cracks on the glass surface during installation and use, and effectively protecting the integrity and sealing of the light window.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A packaging structure for a photoconductive switch with in-plane electrodes, characterized in that, include: The encapsulation housing (1) has an encapsulation chamber (111) inside, and the photoconductive switch (10) is disposed in the encapsulation chamber (111). The encapsulation chamber (111) is filled with transparent insulating oil, and the transparent insulating oil surrounds the photoconductive switch (10). The top of the encapsulation housing (1) is provided with a first light window (121), and the first light window (121) corresponds vertically to the light-transmitting trigger area (103) on the front of the photoconductive switch (10). An output connector (2), disposed through one side wall of the encapsulation housing (1), is used to connect the first electrode (101) of the photoconductive switch (10) to an external circuit; and A power supply connector (3) is provided through the other side wall of the encapsulation housing (1) for connecting the second electrode (102) of the photoconductive switch (10) to the power supply line.

2. The packaging structure of the photoconductive switch with coplanar electrodes as described in claim 1, characterized in that, The bottom wall of the encapsulation chamber (111) is provided with a connecting groove (112), which is connected to the encapsulation chamber (111); the two sides of the opening of the connecting groove (112) are respectively used to support the two ends of the photoconductive switch (10), and the connecting groove (112) is filled with the transparent insulating oil so that the transparent insulating oil covers the bottom of the photoconductive switch (10).

3. The packaging structure of the photoconductive switch with coplanar electrodes as described in claim 2, characterized in that, The bottom of the encapsulation housing (1) is provided with a second light window (113), which corresponds vertically to the connecting groove (112). The second light window (113) is used to guide the trigger light from the back of the light guide switch (10) to illuminate the light-transmitting trigger area (103).

4. The packaging structure of the photoconductive switch with coplanar electrodes as described in claim 2, characterized in that, The packaging shell (1) has a first groove (13) with an outward opening on one side wall, and the inner wall of the first groove (13) has a connection hole (131) communicating with the packaging chamber (111). The output connector (2) is an output insulator (21). The inner end of the pin of the output insulator (21) is connected to the first electrode (101). The outer end of the pin of the output insulator (21) is connected to an external circuit through an RF connector. The connection end of the RF connector is connected to the connection hole (131). The first groove (13) is used to fill insulating sealant.

5. The packaging structure of the photoconductive switch with coplanar electrodes as described in claim 4, characterized in that, The other side wall of the encapsulation housing (1) is provided with a second groove (14) with the opening facing outward, and the second groove (14) is arranged opposite to the first groove (13); The power supply connector (3) is a power supply insulator (31). The inner end of the needle of the power supply insulator (31) is connected to the second electrode (102), and the outer end of the needle of the power supply insulator (31) is connected to the power supply line. The distance between the needle of the power supply insulator (31) and the groove sidewall of the second groove (14) is not less than 3mm, and the second groove (14) is used to fill the insulating sealant.

6. The packaging structure of the photoconductive switch with coplanar electrodes as described in claim 5, characterized in that, The distance from the vertical centerline of the connecting groove (112) to the inner wall of the first groove (13) is less than the distance from the vertical centerline of the connecting groove (112) to the inner wall of the second groove (14), so that the first electrode (101) is close to the output insulator (21); The bottom wall of the encapsulation chamber (111) is provided with an upward-opening isolation groove (114). The isolation groove (114) is located near the side wall of the encapsulation chamber (111) adjacent to the second groove (14). The isolation groove (114) corresponds vertically to the pin of the power supply insulator (31).

7. The packaging structure of the photoconductive switch with coplanar electrodes as described in claim 2, characterized in that, The bottom wall of the encapsulation chamber (111) is provided with an upward-opening first transition groove (115), which is connected to the connecting groove (112).

8. The packaging structure of the photoconductive switch with coplanar electrodes as described in claim 7, characterized in that, The bottom wall of the encapsulation chamber (111) is also provided with a second transition groove (116) opening upwards, and the second transition groove (116) communicates with the connecting groove (112); the second transition groove (116) and the first transition groove (115) both extend to the same side of the connecting groove (112), and the extension length of the second transition groove (116) is greater than the extension length of the first transition groove (115).

9. The packaging structure of the photoconductive switch with coplanar electrodes as described in claim 3, characterized in that, The encapsulation housing (1) includes a base (11) and a cover plate (12). The cover plate (12) is fastened to the top of the base (11), and the encapsulation chamber (111) is formed between the cover plate (12) and the base (11). The first light window (121) is disposed on the cover plate (12), and the second light window (113) is disposed on the bottom wall of the base (11). The top surface of the base (11) is provided with a circumferentially extending sealing groove (117), the sealing groove (117) is located on the outer periphery of the encapsulation chamber (111), the sealing groove (117) is embedded with a sealing ring (4), the bottom surface of the cover plate (12) is provided with a pressing boss (122), the pressing boss (122) is inserted into the sealing groove (117), and the bottom surface of the pressing boss (122) abuts against the sealing ring (4).

10. The packaging structure of the photoconductive switch with coplanar electrodes as described in claim 9, characterized in that, The top surface of the glass of the first light window (121) is lower than the top surface of the cover plate (12); the bottom surface of the glass of the second light window (113) is higher than the bottom surface of the base (11).

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