Low stress in-plane light guide switch

Abstract

The application provides a low-stress coplanar waveguide switch, which comprises a ceramic bottom plate, a central area of the ceramic bottom plate is provided with a light-transmitting hole, a corresponding position above the light-transmitting hole is provided with a packaging module, an upper ceramic cover is arranged above the packaging module, an energy storage capacitor is arranged on the peripheral ceramic bottom plate of the packaging module, a high-voltage electrode column and a grounding electrode column are arranged on the periphery of the energy storage capacitor, and an upper ceramic cover is arranged above the packaging module, the energy storage capacitor, and the high-voltage electrode column and the grounding electrode column. The packaging structure adopts a modularization and flexible compression connection mode, and wider repair window and reconstruction capability are achieved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor device packaging, and in particular to a low-stress coplanar photoconductive switch. Background Technology

[0002] Photoconductive switches (PCSS) are light-controlled switches. Due to their picosecond (ps) level response speed, large power capacity, small size, and immunity to electromagnetic interference when triggered by light pulses, they have extremely wide applications in fields such as generating high-power pulses, ultrafast photoelectric control, and terahertz sources.

[0003] Compared with crystalline materials such as Si and GaAs, SiC crystalline materials have advantages such as high breakdown field strength, large bandgap, fast saturated electron velocity, and high thermal conductivity, making them ideal substrate materials for photoconductive switches. To achieve high power output, power input of ≥25KV, and protection against electrical breakdown, SiC crystals are surrounded by large-sized cables, capacitors, electrodes, and heat dissipation structures.

[0004] However, the assembly quality of these large-sized cables, capacitors, electrodes, and heat dissipation structures can damage the SiC crystal structure. At the same time, because the SiC crystal needs to withstand random vibrations and high and low temperature shocks in its operating environment, a low-stress packaging and efficient reconfiguration structure are required. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this application proposes a low-stress coplanar photoconductive switch, the switch comprising:

[0006] A ceramic base plate, wherein a light-transmitting hole is provided in the central area of ​​the ceramic base plate;

[0007] An encapsulation module is provided at the corresponding position above the light-transmitting hole;

[0008] A high-voltage electrode sheet is provided above the packaging module;

[0009] An energy storage capacitor is provided on the outer ceramic base plate of the packaging module. A high-voltage electrode post and a grounding electrode post are provided around the energy storage capacitor. The lower end of the energy storage capacitor is in contact with the grounding electrode plate, and the upper end is in contact with the high-voltage electrode.

[0010] A ceramic cover is provided above the encapsulation module, energy storage capacitor, high-voltage electrode sheet, high-voltage electrode post and grounding electrode post, and the interconnection is achieved by screws.

[0011] In one possible implementation, a thermally conductive layer is provided on the upper surface of the ceramic base plate.

[0012] In one possible implementation, the ceramic base plate, the high-voltage electrode post, and the grounding electrode post are provided with threaded holes, the high-voltage electrode post and the grounding electrode post support and fix the ceramic base plate, and the nut fixes the ceramic top cover.

[0013] In one possible implementation, the ceramic base plate is provided with a locking groove to achieve precise installation of each part.

[0014] In one possible implementation, the grounding electrode plate is fixed on two diagonally arranged high-voltage electrode posts to achieve grounding of the energy storage capacitor.

[0015] In one possible implementation, the high-voltage electrode plate is fixed on two other diagonally arranged high-voltage electrode posts to facilitate power connection.

[0016] In one possible implementation, the ceramic cover is provided with a connection structure for connecting to the output cable.

[0017] In one possible implementation, the encapsulation module includes: an inner electrode and an outer electrode disposed outside the inner motor;

[0018] The inner electrode is provided with an elastic insulating sleeve for electrical isolation and docking guidance, and insulating adhesive is provided between the inner electrode and the outer electrode;

[0019] A positioning pin is provided in the middle of the inner electrode.

[0020] In one possible implementation, the packaging module has a positioning protrusion structure corresponding to the light-transmitting hole, and a SiC wafer is disposed on the positioning protrusion structure. The SiC wafer has an input electrode and an output electrode.

[0021] On the other hand, a method for manufacturing a packaged module is provided, comprising the following steps:

[0022] Step a: Attach the elastic insulating sleeve to the designated position on the output electrode;

[0023] Step b: Solder the output electrode and input electrode to the designated positions on the SiC wafer and check the solder seal.

[0024] Step c: Fill with insulating adhesive, bringing the liquid level to the designated position;

[0025] Step d: Install the fixing pin.

[0026] On the other hand, a method for manufacturing a low-stress coplanar photoconductive switch is also provided, the method comprising the following steps:

[0027] Step S1: Process the ceramic into the specified structure, including a ceramic base plate and a ceramic top cover;

[0028] Step S2: Attach a thermally conductive layer to the ceramic surface, avoiding the alignment area and the assembly stress area;

[0029] Step S3: Install the grounding electrode plate, energy storage capacitor and high voltage electrode plate in sequence;

[0030] Step S4: Install the SiC wafer module according to the alignment groove on the ceramic base plate;

[0031] Step S5: Install the ceramic top cover and align the mounting holes;

[0032] Step S6: Install 4 electrode posts, adjust the grounding electrode plate and the high voltage electrode plate so that the electrode plate leads pass through the electrode posts, and then tighten with torque.

[0033] Due to the application of the above technical solutions, the present invention has the following beneficial effects compared with the prior art: The low-stress coplanar photoconductive switch packaging structure of the present invention, through SiC modular packaging, reconfigurable structure and stress isolation design, can reduce the stress of SiC wafer and improve the reconfigurability of packaging, thereby improving the reliability and service life of the switch. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the cross-sectional structure of a coplanar optical guide switch in an exemplary embodiment of the present invention;

[0036] Figure 2 This is a cross-sectional view of the SiC packaging module in an exemplary embodiment of the present invention;

[0037] Figure 3 This is a flowchart of the SiC module packaging process in an exemplary embodiment of the present invention;

[0038] Figure 4 This is a flowchart of the packaging process for a coplanar photoconductor switch in an exemplary embodiment of the present invention;

[0039] Figure 5 This is a three-dimensional diagram of the grounding and high-voltage electrode contact transition in an exemplary embodiment of the present invention;

[0040] Figure 6 This is a stress cloud diagram for the simulation optimization of the SiC packaging module structure in an exemplary embodiment of the present invention;

[0041] Figure 7 This is a design diagram of the same-plane metal electrodes of a SiC wafer in an exemplary embodiment of the present invention.

[0042] Labeling Explanation: 101-SiC wafer; 102-Ceramic substrate; 103-Heat-conducting layer; 104-Grounding electrode; 105-High-voltage electrode post; 106-Energy storage capacitor; 107-Grounding electrode post; 108-High-voltage electrode; 109-Ceramic top cover; 110-Output cable; 201-Encapsulation module; 202-Outer electrode; 203-Insulating adhesive; 204-Inner electrode; 205-Positioning pin; 206-Elastic insulating sleeve; 207-Positioning protrusion structure; 501-Card slot. Detailed Implementation

[0043] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0044] In order to achieve a minimized reconfigurable structure for photoconductive switches and improve the reliability and lifespan of switch operation, this application provides the following technical solutions.

[0045] See Figure 1 This invention provides a low-stress coplanar photoconductive switch, comprising: a ceramic base plate 102, with a light-transmitting hole in the central region of the ceramic base plate 102; an encapsulation module 201 positioned above the light-transmitting hole; a ceramic top cover 109 positioned above the encapsulation module 201; an energy storage capacitor 106 positioned on the outer ceramic base plate of the encapsulation module 201; a high-voltage electrode post 105 and a grounding electrode post 107 positioned around the energy storage capacitor 106; and a ceramic top cover 109 positioned above the encapsulation module, the energy storage capacitor, the high-voltage electrode post, and the grounding electrode post.

[0046] See Figure 2The SiC wafer 101 module packaging model is designed using the above-mentioned electrode pattern. Due to the environmental factors of photoconductive switch applications, the SiC wafer 101 requires a highly reliable structure to support the long lifespan and high heat dissipation of the device. To ensure that the SiC wafer 101 is not damaged by stress, the following structure is implemented: the inner electrode and the outer electrode are connected by an insulating adhesive. The inner electrode 204 requires a diameter of 6mm for microwave transmission, and a 1mm protrusion is added in the middle to cooperate with the insulating adhesive 203 to reduce the stress of cable assembly. A fixed elastic insulating sleeve 206 is installed on the upper end of the inner electrode 204. A positioning protrusion structure 207 is provided at the corresponding light-transmitting hole of the packaging module. The SiC wafer is placed at the positioning protrusion structure 207, and the input electrode and output electrode are provided on the SiC wafer. The structure and shape of the outer electrode are determined by simulation. A step is provided at the upper end of the outer electrode to match the high-voltage electrode plate. A guide boss is provided on the lower end face of the outer electrode for ceramic base plate assembly and positioning.

[0047] See Figure 3 The elastic insulating sleeve 206 is inserted into the inner electrode 204, with a negative tolerance in the inner circle of the elastic insulating sleeve 206; the inner electrode 204, the outer electrode 202, and the SiC wafer 101 are brazed together by a fixture; then the welding surface is checked for any gaps.

[0048] In a preferred embodiment, the interconnection of the inner electrode, the outer electrode, and the SiC wafer is not limited to welding, but can also be extended to silver paste bonding.

[0049] Insulating adhesive is poured into the cavity of the external electrode and cured at room temperature for 48 hours. After that, positioning pin 205 is installed.

[0050] See Figure 4 The ceramic base plate 102 is formed by mold making and precision carving. Threads are processed at the assembly point of the electrode post 105, and then the heat-conducting layer 103 is attached.

[0051] In a preferred embodiment, the thermally conductive layer may be a copper film with an oxide film, graphene, or other highly thermally conductive materials.

[0052] See Figure 5 The electrodes are distributed and grounding electrode 104 is assembled. A slot 501 is provided on the ceramic base plate to achieve precise installation of each part. The energy storage capacitor 106 and SiC package module 201 are placed and precisely assembled through the slot of the ceramic base plate 102; then the high voltage electrode 108 and ceramic top cover 109 are placed, and the positions of each connection hole are aligned to achieve coaxiality through tooling.

[0053] See Figure 4 Insert the high-voltage electrode post 105 and the grounding electrode post 107, and adjust the force on the four posts to be balanced.

[0054] See Figure 4 The output cable 110 is an external connection; simply tighten it during assembly.

[0055] In a preferred embodiment, the output cable 110 interface connection can be a snap-fit ​​method.

[0056] See Figure 6 Based on the above design structure, the external electrode 202 structure was modeled. A 2mm step was added to the upper end to accommodate the high-voltage electrode 105. To accommodate the height of the energy storage capacitor 106, the external electrode was designed with a height of 14.8mm, matching the height of the energy storage capacitor 106. Simulation was performed using ANSYS software, with static structural simulation module used for static force analysis. The actual stress environment was simplified; the bottom was set as a fixed support, and the stress surface was the contact area of ​​the high-voltage electrode 108. A downward force of 10 Newtons was set for analysis and optimization. Specific structural details were optimized, and the optimal stress cloud diagram was finally obtained (see [link]). Figure 6 It can be seen that the peak stress of the SiC wafer 101 is 0.04 MPa, which is far below the median.

[0057] See Figure 7 In one exemplary implementation, the metal electrode pattern of the SiC wafer 101 adopts a concentric circle structure; the isolation distance between the inner and outer electrodes is set to 3.2 mm, taking into account voltage strength and the breakdown value of the insulating adhesive.

[0058] The present invention also provides a method for manufacturing a low-stress coplanar photoconductive switch, the method comprising the following steps:

[0059] Step S1: Process the ceramic into the specified structure, including a ceramic base plate and a ceramic top cover;

[0060] Step S2: Attach a thermally conductive layer to the ceramic surface, avoiding the alignment area and the assembly stress area;

[0061] Step S3: Install the grounding electrode plate, energy storage capacitor and high voltage electrode plate in sequence;

[0062] Step S4: Install the SiC wafer module according to the alignment groove on the ceramic base plate;

[0063] Step S5: Install the ceramic top cover and align the mounting holes;

[0064] Step S6: Install 4 electrode posts, adjust the grounding electrode plate and the high voltage electrode plate so that the electrode plate leads pass through the electrode posts, and then tighten with torque.

[0065] This article uses specific examples to illustrate the inventive concept in detail. The description of the above embodiments is only for the purpose of helping to understand the core idea of ​​the present invention. It should be noted that any obvious modifications, equivalent substitutions or other improvements made by those skilled in the art without departing from the inventive concept should be included within the protection scope of the present invention.

[0066] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the foregoing claims.

[0067] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

[0068] It should be understood that "multiple" as used in this article refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0069] Those skilled in the art will understand that all or part of the steps of the above embodiments can be implemented by hardware or by a program instructing related hardware. The program can be stored in a computer-readable storage medium, such as a read-only memory, a disk, or an optical disk.

[0070] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A low stress in-plane light guide switch, characterized by, The switch comprises: A ceramic base plate, the center area of which is provided with a light transmission hole; A packaging module is arranged at the corresponding position above the light transmission hole; A high-voltage electrode sheet is arranged above the packaging module; An energy storage capacitor is arranged on the peripheral ceramic base plate of the packaging module, the periphery of which is provided with a high-voltage electrode column and a grounding electrode column, the lower end of the energy storage capacitor is in contact with the grounding electrode sheet, and the upper end is in contact with the high-voltage electrode; A ceramic upper cover is arranged above the packaging module, the energy storage capacitor, the high-voltage electrode sheet, the high-voltage electrode column and the grounding electrode column, and fastening interconnection is realized through screws; A heat conduction layer is arranged on the upper surface of the ceramic base plate; Threaded holes are arranged on the ceramic base plate, the high-voltage electrode column and the grounding electrode column, the high-voltage electrode column and the grounding electrode column support and fix the ceramic base plate, and nuts fix the ceramic upper cover; A clamping groove is arranged on the ceramic base plate to realize precise installation of each part.

2. The photoconductive switch of claim 1, wherein, The grounding electrode sheet is fixed on two high-voltage electrode columns arranged at opposite angles, and cooperation realizes energy storage capacitor grounding.

3. The photoconductive switch of claim 2, wherein, The high-voltage electrode sheet is fixed on the other two high-voltage electrode columns arranged at opposite angles, and cooperation realizes power input.

4. The photoconductive switch of any of claims 1 to 3, wherein, A connecting structure is arranged on the ceramic upper cover for connecting with an output cable.

5. The photoconductive switch of any of claims 1 to 3, wherein, The packaging module comprises an inner electrode and an outer electrode arranged outside the inner electrode; An elastic insulation sleeve for realizing electrical isolation and butt joint guidance is arranged outside the inner electrode, and an insulating glue is arranged between the inner electrode and the outer electrode; A positioning needle is arranged in the middle of the inner electrode.

6. The photoconductive switch of any of claims 1 to 3, wherein, A positioning protruding structure is arranged on the packaging module corresponding to the light transmission hole, a SiC wafer is arranged at the positioning protruding structure, and an input electrode and an output electrode are arranged on the SiC wafer.

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