A three-terminal leaded ceramic capacitor

Abstract

This utility model relates to the field of capacitor technology and discloses a three-terminal ceramic capacitor, including a ceramic substrate and a circuit socket. An electrode paste layer is coated on the outer side of the ceramic substrate, and lead terminals are welded to the outer side of the electrode paste layer. The lead terminals include a double lead arranged on one side and a ground lead arranged on one side. The double lead is a U-shaped copper-clad steel tinned lead terminal, formed by fabricating two through terminals on the same side from the same wire. The ground lead is a copper-clad steel tinned straight lead terminal. This utility model simplifies the production process, improves capacitor yield and high-frequency stability, and balances production efficiency and product reliability.

Description

Technical Field

[0001] This utility model relates to the field of capacitor technology, and in particular to a ceramic capacitor with three leads. Background Technology

[0002] Ceramic capacitors are electronic components that use ceramic material as the dielectric, with electrodes coated on both sides of the ceramic substrate and connected to lead terminals. They store charge through dielectric polarization, and their capacity is related to the dielectric constant of the ceramic, the electrode area, and the thickness of the dielectric. They are widely used in filtering, coupling, and other circuit applications.

[0003] Typically, a two-terminal capacitor is constructed by coating electrodes on both sides of a dielectric substrate and then attaching leads, thus forming a leaded ceramic capacitor structure. Because the leads have a small amount of inductance (residual inductance), they will generate inductance with ground when used as a bypass capacitor. In practical applications, since the capacitor's impedance decreases with increasing frequency, the insertion loss should gradually increase in the high-frequency range. However, due to the residual inductance in practical use, interference is generated, reducing frequency performance and resulting in a V-shaped insertion loss. This lowers the cutoff frequency and affects high-frequency characteristics.

[0004] Therefore, to address the aforementioned problems, a three-terminal ceramic capacitor is proposed. Utility Model Content

[0005] To overcome the above shortcomings, this utility model provides a three-terminal ceramic capacitor, which aims to improve the problem in the prior art where the residual inductance of the leads causes the insertion loss to be V-shaped at high frequencies, resulting in a reduced cutoff frequency and affecting the high-frequency characteristics of two-terminal ceramic capacitors.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A ceramic capacitor with three leads includes a ceramic substrate and a circuit socket. The outer side of the ceramic substrate is coated with an electrode paste layer, and lead terminals are welded to the outer side of the electrode paste layer. The lead terminals include a double lead arranged on the same side and a ground lead arranged on one side. The double lead is a U-shaped copper-clad steel tinned lead terminal, which is made from the same wire to form two terminals that are connected on the same side. The ground lead is a copper-clad steel tinned straight lead terminal. Both the double lead and the ground lead are provided with plug-in components at their ends. The plug-in structure includes an elastic snap-fit ​​part at the end of the lead and a slot part of the circuit socket, and the elastic snap-fit ​​part and the slot part are engaged in a snap-fit ​​cooperation. As a further description of the above technical solution: The elastic buckle part includes elastic arms symmetrically arranged on both sides of the end of the lead wire, and the end of the elastic arm is provided with an outwardly protruding snap-fit ​​protrusion. As a further description of the above technical solution: The slot includes a pressing block, a push button is provided on the top of the pressing block, a snap-fit ​​groove adapted to the shape of the snap-fit ​​protrusion is provided on the inner side of the pressing block, and a spring is fixedly connected between the outer end of the pressing block and the inner side of the circuit socket. As a further description of the above technical solution: The circuit socket has three sliding grooves inside, the outer side of the clamping block is slidably connected to the inside of the sliding groove, and one end of the spring is installed on the inner side of the sliding groove. As a further description of the above technical solution: The elastic arm is made of elastic metal material and its surface is covered with an insulating layer; As a further description of the above technical solution: The ceramic matrix is ​​provided with an encapsulation layer on its outer periphery. The encapsulation layer is composed of matrix resin embedded with micron-sized thermally conductive ceramic particles. The ratio of ceramic particles to resin is 55:45, and the viscosity of the matrix resin is controlled at 500-800 mPa·s. As a further description of the above technical solution: The electrode slurry layer is made of copper-silver composite electrode slurry, which can be used as an electrode material. As a further description of the above technical solution: The welding positions of the double leads and grounding leads to the ceramic substrate are greater than 2 / 3 of the diameter of the circular ceramic substrate, and the welding points of the double leads and grounding leads are at the same position on both sides of the ceramic substrate.

[0007] This utility model has the following beneficial effects: 1. In this utility model, through the synergistic structure of "U-shaped terminal integrated molding design + laser welding process + gradient curing encapsulation layer", the U-shaped terminal eliminates the secondary connection process, the laser welding reduces the heat-affected zone to avoid film damage, and the gradient curing suppresses cracks in the encapsulation layer, thereby achieving the effects of simplifying the production process, improving the yield rate of capacitors and high-frequency stability, and taking into account both production efficiency and product reliability.

[0008] 2. In this utility model, through the matching structure of "elastic buckle part (elastic arm + snap-fit ​​protrusion) and snap-fit ​​groove part (pressing block + spring + snap-fit ​​groove)", the elastic arm retracts during insertion to allow the snap-fit ​​protrusion to be accurately snapped in. During disassembly, pressing the push button compresses the spring to separate the buckle, realizing the quick disassembly and assembly of ceramic capacitors and circuit sockets, avoiding the reliance on tools and component damage of traditional soldering and disassembly, and improving the convenience of electronic circuit maintenance. Attached Figure Description

[0009] Figure 1 This is a three-dimensional schematic diagram of a ceramic capacitor with three-terminal leads proposed in this utility model. Figure 2This is a schematic diagram of the ceramic substrate structure of a three-terminal ceramic capacitor proposed in this utility model; Figure 3 This is a schematic diagram of the circuit socket structure of a three-terminal ceramic capacitor proposed in this utility model; Figure 4 for Figure 3 Enlarged view of point A in the middle.

[0010] Legend: 1. Ceramic substrate; 2. Electrode paste layer; 3. Dual leads; 4. Grounding lead; 5. Encapsulation layer; 6. Elastic arm; 7. Snap-fit ​​protrusion; 8. Circuit socket; 9. Clamping block; 10. Push button; 11. Snap-fit ​​groove; 12. Spring. Detailed Implementation

[0011] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0012] Reference Figures 1 to 4This utility model provides an embodiment of a three-terminal ceramic capacitor, comprising a ceramic substrate 1 and a circuit socket 8. The ceramic substrate 1 serves as the basic carrier of the three-terminal ceramic capacitor, bearing the subsequent processing steps and ensuring the overall structural stability of the capacitor. An electrode paste layer 2 is coated on its outer side. The electrode paste layer 2 uses a copper-silver composite electrode paste, which can be used as an electrode material, to achieve good conductivity, facilitate subsequent lead terminal connection, and reduce costs. Lead terminals are welded to the outer side of the electrode paste layer 2. The lead terminals include a double lead 3 arranged on one side and a ground lead 4 arranged on one side. The double lead 3 and the ground lead 4 are welded to the ceramic substrate 1. The position is larger than 2 / 3 of the diameter of the circular ceramic substrate 1, and the welding point is at the same position on both sides of the ceramic substrate 1, which increases the welding contact area, improves conductivity and connection fixation, and ensures stable and reliable electrical connection. The double lead 3 is a U-shaped copper-clad steel tinned lead terminal, which is made from the same wire to form two terminals that are connected on the same side. No additional conductive support is required, which simplifies the structure and steps and achieves circuit connection efficiently. The copper-clad steel tinned material ensures conductivity and mechanical strength. The grounding lead 4 is a copper-clad steel tinned straight lead terminal. With copper-clad steel tinned material, it has good conductivity and mechanical strength, realizes the capacitive grounding function, and ensures the electrical safety and stability of circuit operation. An encapsulation layer 5 is provided on the outer periphery of the ceramic substrate 1. The encapsulation layer 5 is composed of micron-sized thermally conductive ceramic particles embedded in the matrix resin. The ratio of ceramic particles to resin is 55:45. The viscosity of the matrix resin is controlled at 500-800 mPa·s. The embedded micron-sized thermally conductive ceramic particles improve the high-frequency thermal stability of the capacitor. The matrix resin ensures appropriate fluidity for easy molding, thus controlling the cost of raw materials while ensuring the performance of the encapsulation layer 5.

[0013] Both the double lead 3 and the grounding lead 4 have plug-in connectors at their ends. The plug-in structure includes an elastic snap-fit ​​part at the end of the lead and a slot part of the circuit socket 8. The elastic snap-fit ​​part and the slot part engage with each other, providing a convenient and detachable way to connect the capacitor to the circuit, facilitating installation, replacement, and maintenance. The elastic snap-fit ​​part includes elastic arms 6 symmetrically arranged on both sides of the end of the lead. Made of elastic metal material, it has elastic deformation capability to meet the shrinkage and recovery requirements during the snap-fit ​​process. The surface is covered with an insulating layer to prevent short circuits between adjacent elastic arms 6 and ensure stable electrical performance. The end of the elastic arm 6 has an outwardly protruding snap-fit ​​protrusion 7, which can be adapted to engage with the snap-fit ​​groove 11 of the slot part to achieve mechanical and electrical connection fixation. The slot includes a clamping block 9. The circuit socket 8 has three sliding grooves inside, providing a sliding track for the clamping block 9, limiting the direction of movement, and ensuring accurate and stable engagement. The outer side of the clamping block 9 is slidably connected inside the sliding groove, and one end of the spring 12 is installed inside the sliding groove. The top of the clamping block 9 is provided with a push button 10, which can drive the clamping block 9 to move by pressing it, compressing the spring 12 to achieve snap-fit ​​and separation, which is convenient and quick. The inner side of the clamping block 9 has a snap-fit ​​groove 11 that matches the shape of the snap-fit ​​protrusion 7, which is used to accommodate the snap-fit ​​protrusion 7, ensuring the mechanical strength and electrical stability of the connection. The outer end of the clamping block 9 is fixedly connected to the inner side of the circuit socket 8 with the spring 12, which uses its own elasticity to push the clamping block 9 to move, so that the snap-fit ​​protrusion 7 is firmly snapped into the snap-fit ​​groove 11, ensuring the reliability of the snap-fit ​​engagement. When disassembling, external force compresses the spring 12 to separate it, providing power for disassembly and assembly.

[0014] Working Principle: In the fabrication of three-terminal ceramic capacitors, ceramic powder (such as BaTiO3), binder, solvent, and additives are first ball-milled and mixed in proportion to form a uniformly suspended ceramic slurry. The slurry must be stable to avoid agglomeration, which directly affects capacitor performance. Additives include dispersants (to prevent ceramic powder from sticking together), plasticizers (to improve diaphragm flexibility), and defoamers (to avoid bubble defects). The prepared mixture is then ball-milled to achieve nanoscale uniform mixing, ensuring material consistency. The uniformly mixed slurry is granulated to form granular material suitable for molding processes. The granulated material is then pressed or cast into the desired circular blank. The formed blank is sintered in a high-temperature furnace, causing the organic matter to volatilize and the ceramic body to densify, ensuring the capacitor's electrical performance and mechanical strength. A layer of copper-silver composite electrode paste (replacing pure silver paste) is brushed onto the surface of the sintered ceramic body as the electrode material, facilitating subsequent electrode connection and conductivity while reducing costs.

[0015] The U-shaped copper-clad steel tinned lead terminals, made from the same wire, form two through-terminals on the same side. These two through-terminals eliminate the need for two unconnected terminals to be connected by other conductive supports. The structure is simple and the steps are straightforward. The U-shaped terminal is spot-welded to one side of the circular ceramic sheet after electrode paste application. Another pre-prepared copper-clad steel tinned straight lead terminal is spot-welded to the other side of the circular ceramic sheet after electrode paste application, ensuring electrical continuity. Except for the semi-circular bend, the U-shaped terminal must be straight and evenly spaced. The spot-welding points of the U-shaped and straight leads to the circular ceramic should be larger than 2 / 3 of the ceramic's diameter, and the top of the U-shaped lead and the top of the straight lead should be at the same position on both sides of the ceramic to improve conductivity and stability. Laser welding is used instead of traditional spot welding / dip welding. Solder wire laser welding technology is employed to reduce the heat-affected zone (<0.1mm), avoid film damage, and improve welding precision.

[0016] The encapsulation material uses micron-sized thermally conductive ceramic particles embedded in the matrix resin to improve high-frequency thermal stability. The viscosity of the matrix resin is controlled at 500-800 mPa·s (25℃) to ensure fluidity. A moderate ratio of ceramic to resin of 55:45 is used. When the ceramic content exceeds 65%, the fluidity of the slurry decreases, which can easily lead to uneven thickness of the encapsulation layer 5 or residual air bubbles. The unit price of ceramic particles is generally lower than that of high-performance resins, and appropriately increasing the proportion can reduce raw material costs. When the ceramic content is less than 50%, the impact resistance and temperature resistance of the cured encapsulation layer 5 may be insufficient. Refined ceramic powder (purity ≥99.7%) is used instead of high-purity powder (purity ≥99.99%). This process can reduce raw material costs by approximately 20% to 30%. Ceramic powder with a D50 particle size of 0.5 to 1.5 μm is selected. For excessively fine particles (e.g., <0.3 μm), the amount of dispersant needs to be increased, leading to higher costs. A polymeric resin-based binder, primarily polyvinyl butyral (PVB) or acrylic resin, is added to provide adhesion between ceramic particles, preventing agglomeration and forming an interpenetrating network structure with the epoxy resin matrix, thus improving interfacial bonding strength. A planetary mixer is used, and the process is optimized through ball milling at 200-300 rpm for 40 minutes. A three-roll mill is then used for secondary homogenization, with a roller gap ≤10 μm, to eliminate agglomeration. The composite material is injected into the mold cavity using a vacuum injection molding machine (pressure 0.6-0.8 MPa, temperature 80-100℃) to encapsulate the capacitor chip, followed by gradient curing (60℃ / 1h → 100℃ / 2h → 150℃ / 1h) to suppress internal stress cracking.

[0017] When connecting the ceramic capacitor to the circuit socket 8, the operation is as follows: Hold the ceramic substrate 1 and align the elastic latches at the ends of the dual leads 3 and the ground lead 4 with the corresponding slots on the circuit socket 8. At this time, the elastic latches include elastic arms 6 symmetrically arranged on both sides of the lead ends, made of elastic metal material and covered with an insulating layer. The ends of the elastic arms 6 have outwardly protruding latching protrusions 7. Insert the dual leads 3 and the ground lead 4 into the circuit socket 8. During insertion, the elastic arms 6 are compressed by the inside of the circuit socket 8, gradually contracting and deforming, causing the latching protrusions 7 to move closer to the elastic arms 6, so that they can smoothly enter the interior of the circuit socket 8. When the latching protrusions 7 reach the position of the slots inside the circuit socket 8, the clamping block 9 of the slot, under the action of the spring 12, will have its inner latching groove 11, which matches the shape of the latching protrusions 7, precisely engage with the latching protrusions 7. Since one end of the spring 12 is installed inside the inner groove of the circuit socket 8, and the outer side of the clamping block 9 is slidably connected inside the groove, the elastic force of the spring 12 will push the clamping block 9 to move, so that the snap-fit ​​protrusion 7 is snapped into the snap-fit ​​groove 11, completing the snap-fit ​​engagement between the ceramic capacitor and the circuit socket 8, and realizing the electrical connection.

[0018] When it is necessary to disassemble the ceramic capacitor, locate the push button 10 on the top of the clamping block 9 on the circuit socket 8. By pressing the push button 10, the clamping block 9 is moved away from the locking protrusion 7, compressing the spring 12 and separating the locking protrusion 7 from the locking groove 11. Pull out the ceramic substrate 1. As the elastic arms 6 at the ends of the double leads 3 and the ground lead 4 are removed from the circuit socket 8, they are no longer compressed and gradually return to their original shape until the ceramic capacitor is completely removed from the circuit socket 8, so that it can be replaced or repaired later. The entire process, through the above series of steps, achieves convenient connection and disconnection between the three-terminal ceramic capacitor and the circuit socket 8, ensuring the efficiency of capacitor installation and maintenance in electronic circuits.

[0019] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A three-terminal ceramic capacitor, comprising a ceramic substrate (1) and a circuit socket (8), characterized in that: The outer side of the ceramic substrate (1) is coated with an electrode paste layer (2), and the outer side of the electrode paste layer (2) is welded with lead terminals. The lead terminals include double leads (3) arranged on the same side and grounding leads (4) arranged on one side. The double leads (3) are U-shaped copper-clad steel tinned lead terminals, which are made from the same wire to form two terminals that are connected on the same side. The grounding lead (4) is a copper-clad steel tinned straight lead terminal. Both the double lead (3) and the ground lead (4) are provided with plugs at their ends. The plugs include an elastic snap-fit ​​part at the end of the lead and a slot part of the circuit socket (8), and the elastic snap-fit ​​part and the slot part are engaged.

2. A ceramic capacitor with three leads according to claim 1, characterized in that: The elastic buckle part includes elastic arms (6) symmetrically arranged on both sides of the end of the lead wire, and the end of the elastic arm (6) is provided with an outwardly protruding snap-fit ​​protrusion (7).

3. A ceramic capacitor with three leads according to claim 2, characterized in that: The slot includes a pressing block (9), a push button (10) is provided on the top of the pressing block (9), a snap-fit ​​groove (11) that matches the shape of the snap-fit ​​protrusion (7) is provided on the inner side of the pressing block (9), and a spring (12) is fixedly connected between the outer end of the pressing block (9) and the inner side of the circuit socket (8).

4. A ceramic capacitor with three leads according to claim 3, characterized in that: The circuit socket (8) has three grooves inside, the outer side of the clamping block (9) is slidably connected to the inside of the groove, and one end of the spring (12) is installed inside the groove.

5. A ceramic capacitor with three leads according to claim 2, characterized in that: The elastic arm (6) is made of elastic metal material and its surface is covered with an insulating layer.

6. A ceramic capacitor with three leads according to claim 1, characterized in that: The ceramic matrix (1) has an encapsulation layer (5) on its outer periphery. The encapsulation layer (5) is composed of micron-sized thermally conductive ceramic particles embedded in the matrix resin. The ratio of ceramic particles to resin is 55:45, and the viscosity of the matrix resin is controlled at 500-800 mPa·s.

7. A ceramic capacitor with three leads according to claim 1, characterized in that: The electrode slurry layer (2) is made of copper-silver composite electrode slurry, which can be used as an electrode material.

8. A ceramic capacitor with three leads according to claim 1, characterized in that: The welding positions of the double lead (3) and the ground lead (4) to the ceramic substrate (1) are greater than 2 / 3 of the diameter of the circular ceramic substrate (1), and the welding points of the double lead (3) and the ground lead (4) are at the same position on both sides of the ceramic substrate (1).

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