A vertical interconnect high-precision coplanar capacitive displacement sensor and a manufacturing method thereof
By generating a central electrode and a protective ring in situ on a single insulating substrate, combined with vertical interconnection and double insulating dielectric encapsulation, the assembly error and coplanarity problems of traditional capacitive displacement sensors are solved, achieving high-precision and stable capacitive displacement measurement.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SANYING MOTIONCONTORL TIANJIN INSTR CO LTD
- Filing Date
- 2026-02-03
- Publication Date
- 2026-06-12
Smart Images
Figure CN122192138A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of capacitive displacement sensor technology, and specifically to a vertically interconnected high-precision coplanar capacitive displacement sensor and its manufacturing method. Background Technology
[0002] A high-precision capacitive displacement sensor is a precision sensing device that performs non-contact measurement based on the principle of capacitance. Its core principle is to detect the change in capacitance between the sensor probe and the conductive object being measured, and convert this change into a highly linear electrical signal, thereby achieving precise measurement of minute displacements or gaps at the nanometer to submicrometer level. Due to its extremely high resolution, stability, and dynamic response characteristics, it is widely used in precision manufacturing, microelectronics engineering, and industrial inspection.
[0003] Existing high-precision capacitive displacement sensors typically employ a triaxial structure of "center electrode-protective ring-housing". However, the existing technology has the following problems: 1. Large error in separate assembly: In existing technologies, the center electrode and the guard ring are usually two separate metal parts assembled in the middle by an insulating sleeve. This "sandwich" mechanical assembly has serious cumulative tolerances, making it difficult to ensure the concentricity of the center electrode and the guard ring, resulting in asymmetrical electric field distribution and affecting linearity.
[0004] 2. Coplanarity is difficult to control: Due to the different parts being assembled, each part has a different coefficient of thermal expansion and there are assembly gaps, making it difficult to ensure that the front end face is on the same plane, which can easily lead to steps during grinding and polishing.
[0005] 3. Lead interference: Traditional lateral leads compromise the integrity of the protective ring.
[0006] Therefore, how to provide a vertically interconnected high-precision coplanar capacitive displacement sensor to overcome the shortcomings of existing technologies is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention
[0007] Therefore, the present invention provides a vertically interconnected high-precision coplanar capacitive displacement sensor to solve the problems in the prior art.
[0008] To achieve the above objectives, the present invention provides the following technical solution: This invention discloses a vertically interconnected high-precision coplanar capacitive displacement sensor, comprising: Metal casing; An insulating substrate is disposed inside the metal casing; A functional electrode layer is disposed on the front end surface of the insulating substrate; An insulating trench is formed on the front end face of the insulating substrate, and the insulating trench divides the functional electrode layer into a concentric central electrode and a protective ring; At least two sets of metallized vias are provided, which penetrate through the interior of the insulating substrate. The center electrode and the guard ring respectively cover and are electrically connected to the top of the corresponding metallized via. The signal lead is electrically connected to the metallized via.
[0009] Furthermore, the interior of the insulating trench is filled with a first insulating medium for supporting the edge of the central electrode, the first insulating medium being a high-hardness rigid material; the space between the insulating substrate and the inner wall of the metal shell is filled with a second insulating medium for suspending and fixing the insulating substrate, the second insulating medium being a low-modulus flexible material.
[0010] Furthermore, the depth of the insulating trench is greater than the thickness of the functional electrode layer, and the insulating trench extends to the front end face of the insulating substrate and forms an overcut anchoring structure.
[0011] Furthermore, the functional electrode layer includes a seed layer and a main metal layer stacked with the seed layer.
[0012] Furthermore, the seed layer is a titanium layer or a chromium layer, and the main metal layer is a gold layer or a copper layer.
[0013] Furthermore, the first insulating medium is a high-temperature epoxy resin with a Shore hardness of D85 or higher, and the second insulating medium is a low-modulus modified silicone rubber or polyurethane elastomer.
[0014] Furthermore, the mixed surface composed of the metal shell end face, the central electrode, the protective ring, the first insulating medium, and the second insulating medium is ground and polished to form a seamless full-plane structure.
[0015] Furthermore, the insulating substrate is an integrally formed columnar structure, and the central electrode and the protective ring are metal thin film layers.
[0016] Furthermore, the metallized via is formed by filling conductive silver paste with a through hole that extends through the interior of the insulating substrate using a vacuum casting method and then co-firing at high temperature. The signal lead is soldered to the bottom surface of the metallized via.
[0017] According to a second aspect of the present invention, a method for manufacturing the aforementioned vertically interconnected high-precision coplanar capacitive displacement sensor is provided, comprising the following steps: S1. Substrate preparation: Through holes are machined and metallized on a single piece of insulating material; S2, In-situ forming: A functional electrode layer is formed on the front end face of the insulating substrate. The center electrode and the protective ring are separated in-situ through a precision removal process, and the concentricity is directly guaranteed by the processing precision. S3, rigid filling: fill the divided insulation trenches with a high-hardness rigid material; S4, Flexible Assembly: The insulating substrate is placed into the metal shell, and a low-modulus flexible material is injected into the annular gap between the insulating substrate and the metal shell. S5, Overall Coplanarity: The front face of the insulating substrate is uniformly ground.
[0018] The present invention has the following advantages: This invention achieves "self-alignment" by setting a single integral insulating substrate and generating the central electrode and protective ring in situ through a "coating + scribing / photolithography" process. It abandons the traditional split structure and reduces the concentricity error from the 0.05mm level of traditional assembly to the 0.005mm level, significantly improving the linearity and interchangeability of the sensor.
[0019] By incorporating metallized vias and signal leads, an inverted T-shaped conductive structure is formed, avoiding damage to the electrode pattern caused by surface welding. This vertical interconnection design ensures that the sensor's front-end face is completely free of any protruding solder joints, leads, or via pits. Combined with subsequent grinding and polishing of the multi-medium hybrid surface—comprising the metal housing end face, flexible rubber layer, protective ring, hard resin layer, and central electrode—an atomically smooth and flat surface is achieved on the sensor's front-end face. This surface is less prone to dust accumulation, exhibits excellent aerodynamic characteristics, and can operate safely in applications with extremely small gaps, such as air bearings. Furthermore, it completely eliminates the cutting interference of traditional lateral leads on the protective ring's electric field.
[0020] By setting a second insulating medium between the insulating substrate and the metal shell, a flexible encapsulation of the integral substrate is achieved, completely cutting off the stress transmission path of the shell, thereby ensuring the long-term stability of the electrode geometry and solving the temperature drift problem. Attached Figure Description
[0021] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.
[0022] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.
[0023] Figure 1 A perspective view of the vertically interconnected high-precision coplanar capacitive displacement sensor provided by the present invention; Figure 2 Cross-sectional view of the vertically interconnected high-precision coplanar capacitive displacement sensor provided by the present invention; Figure 3 A cross-sectional view of the vertically interconnected high-precision coplanar capacitive displacement sensor provided by the present invention; Figure 4 Top view of the vertically interconnected high-precision coplanar capacitive displacement sensor provided by the present invention; Figure 5 A schematic diagram of the microstructure of the functional electrode layer and insulating trench provided by the present invention; Figure 6 This is a schematic diagram illustrating the signal transmission principle provided by the present invention.
[0024] In the figure: 1 Metal casing; 3 Insulating substrate; 4 Functional electrode layer; 41 Seed layer; 42 Main metal layer; 5 Insulating trench; 6 Center electrode; 7 Guard ring; 8 Metallized via; 9 Signal lead; 10 First insulating medium; 11 Second insulating medium. Detailed Implementation
[0025] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0026] Please refer to Figures 1-6 The vertically interconnected high-precision coplanar capacitive displacement sensor disclosed in this invention will now be described. This invention consists of six parts, as follows: Figure 1 , Figure 2As shown, the device includes a metal casing 1, an insulating substrate 3, a functional electrode layer 4, an insulating trench 5, metallized vias 8, and signal leads 9. The insulating substrate 3 is disposed inside the metal casing 1. The functional electrode layer 4 is disposed on the front end face of the insulating substrate 3. The insulating trench 5 is formed on the front end face of the insulating substrate 3. The insulating trench 5 divides the functional electrode layer 4 into a concentric central electrode 6 and a protective ring 7. At least two sets of metallized vias 8 are provided, penetrating inside the insulating substrate 3. The central electrode 6 and the protective ring 7 respectively cover and are electrically connected to the top of the corresponding metallized via 8. The signal leads 9 are electrically connected to the metallized via 8.
[0027] Preferably, the insulating substrate 3 is a one-piece molded columnar structure, and the central electrode 6 and the protective ring 7 are metal thin film layers. Preferably, the functional electrode layer 4 includes a seed layer 41 and a main metal layer 42 stacked with the seed layer 41.
[0028] This application presents an integrated structure based on a monolithic substrate, the specific structure of which is as follows: Figure 1 , Figure 2 As shown. The vertically interconnected high-precision coplanar capacitive displacement sensor provided in this embodiment differs from the multi-part mechanical assembly structure of "central electrode 6 pillars + insulating sleeve + protective ring 7 sleeve" in traditional technology. This sensor has a core component - a single integral insulating substrate 3.
[0029] 1. Substrate Material: The insulating substrate 3 is made of a material with a low coefficient of thermal expansion and extremely high rigidity, such as 99% alumina ceramic or microcrystalline glass, and is made into a cylindrical structure. The integrated structure eliminates the cumulative tolerances and thermal stress interfaces caused by the assembly of multiple components.
[0030] 2. Electrode Forming: The central electrode 6 and the protective ring 7 are not independently manufactured metal parts, but rather functional electrode layers 4 grown in situ on the front end face of the insulating substrate 3. Specifically, using magnetron sputtering or vacuum evaporation, a high-adhesion seed layer 41 is first deposited on the front end face of the insulating substrate 3, followed by the deposition of a high-conductivity main metal layer 42. The seed layer 41 serves to anchor the ceramic substrate and the main metal layer 42 at the atomic level, ensuring that the extremely thin functional electrode layer 4 will not peel or flake off during subsequent drastic in-situ cutting and coplanar polishing processes. Preferably, the seed layer 41 is a titanium or chromium layer, and the main metal layer 42 is a gold or copper layer.
[0031] 3. Self-alignment concentricity: such as Figure 5 As shown, the insulating trench 5 between the central electrode 6 and the protective ring 7 is not formed by the gap in the component assembly, but is formed by in-situ cutting on the functional electrode layer 4 using high-precision laser etching or diamond tools. Preferably, as shown... Figure 5As shown, the depth of the insulating trench 5 is greater than the thickness of the functional electrode layer 4, and the insulating trench 5 extends to the front end surface of the insulating substrate 3 and forms an overcut anchoring structure.
[0032] The advantage of this is that the concentricity of the center electrode 6 and the protective ring 7 depends entirely on the positioning accuracy of the machine tool (up to the micrometer level), realizing the "self-alignment" of the structure and completely eliminating the risk of eccentricity that is difficult to avoid in traditional mechanical assembly, thereby ensuring the high symmetry of the electric field distribution of the protective ring 7.
[0033] This application establishes a vertical interconnect structure based on metallized vias 8, the specific structure of which is as follows: Figure 2 , Figure 3 , Figure 6 As shown. This embodiment focuses on demonstrating the vertical signal output path of the sensor, which is the key electrical foundation for achieving the "fully planar seamless structure" of the front end. Inside the monolithic insulating substrate 3, at least two sets of metallized vias 8 are pre-fabricated, penetrating its axial thickness.
[0034] Preferably, the metallized via 8 is formed by an axial through-hole extending into the insulating substrate 3, filled with conductive silver paste using vacuum casting, and then co-fired at high temperature. The signal lead 9 is soldered to the bottom surface of the metallized via 8. The conductive silver paste inside the metallized via 8 is co-fired at high temperature to form a solidified columnar structure, and the signal lead 9 is soldered to its bottom to form electrical conductivity.
[0035] Preferably, the mixed surface consisting of the end face of the metal shell 1, the central electrode 6, the protective ring 7, the first insulating medium 10, and the second insulating medium 11 is ground and polished to form a seamless full-plane structure.
[0036] 1. Central signal path: The central electrode 6 directly covers the top of the metallized via 8 located at the center of the insulating substrate 3, and the two form an electrical connection.
[0037] 2. Guard ring 7 signal path: Guard ring 7 covers the top of the metallized via 8 (or a set of via arrays) located on the periphery of the substrate, forming electrical conduction.
[0038] like Figure 6 As shown, this connection method forms an "inverted T-shaped" conductive structure. The top of the metallized via 8 is microscopically fused with the functional electrode layer 4 (seed layer 41 is a titanium / chromium layer, and main metal layer 42 is a gold / copper thin film), without the need for any solder or conductive adhesive; the bottom of the metallized via 8 extends to the back of the insulating substrate 3 and forms a "pad structure" for soldering. The signal lead 9 is connected to the "pad structure" by reflow soldering or conductive adhesive.
[0039] This vertical interconnect design ensures that the sensor front face is completely free of any protruding solder joints, leads, or via pits. Combined with subsequent grinding processes, the sensor front face can be machined into a perfect mirror finish, allowing the sensor to operate safely in applications with extremely small gaps (<10μm), such as air bearings, and completely eliminating the cutting interference of traditional lateral leads on the electric field of the guard ring 7.
[0040] like Figure 3 , Figure 4 As shown, the interior of the insulating trench 5 is filled with a first insulating medium 10 for supporting the edge of the central electrode 6. The first insulating medium 10 is a high-hardness rigid material. The space between the insulating substrate 3 and the inner wall of the metal shell 1 is filled with a second insulating medium 11 for suspending and fixing the insulating substrate 3. The second insulating medium 11 is a low-modulus flexible material. Preferably, the first insulating medium 10 is a high-temperature epoxy resin with a Shore hardness of D85 or higher, and the second insulating medium 11 is a low-modulus modified silicone rubber or polyurethane elastomer.
[0041] This application presents a double-insulated encapsulation structure. The specific structure is as follows: Figure 3 , Figure 4 As shown in the figure. The following detailed examples illustrate how to resolve the technical contradiction between "coplanar machining accuracy" and "environmental stress isolation".
[0042] 1. Dual differentiated packaging strategy, such as Figure 3 and Figure 4 As shown. This application innovatively employs a combination of "hard inside and soft outside" filling media: Inner hard dielectric layer: Filled within the insulating trench 5 between the central electrode 6 and the protective ring 7. In this embodiment, a high-temperature epoxy resin with a Shore hardness of D85 or higher is selected.
[0043] Operating principle: Because this location is in the core sensing area and is extremely narrow (typically <0.5mm), hard resin can provide mechanical strength similar to that of metal electrodes and ceramic substrates. During the final coplanar grinding and polishing, the hard resin will not dent, ensuring the sharpness and flatness of the electrode edges.
[0044] Outer flexible medium: fills the annular gap between the outer edge of the protective ring 7 and the inner wall of the metal shell 1. In this embodiment, a low-modulus modified silicone rubber or polyurethane elastomer is selected.
[0045] Working principle: This layer acts as a "suspending damper". For example... Figure 3 As shown, when the metal casing 1 undergoes mechanical deformation due to the tightening of the mounting threads, or when it expands and contracts due to changes in ambient temperature, this flexible medium absorbs stress through its own elastic deformation, blocking the transmission of stress to the internal rigid substrate, thereby ensuring the long-term stability of the electrode's geometric position.
[0046] The purpose of this application is: The core objective of this application is to solve the assembly problem of the three coaxial structure of the traditional capacitive displacement sensor, namely "center electrode 6-protective ring 7-shell", and to provide a capacitive sensor based on "integrated substrate + in-situ molding".
[0047] The technical solution of the present invention: 1. Integrated Electrode Design: Abandoning separate components, a single, integral insulating substrate 3 is adopted. The central electrode 6 and protective ring 7 are generated in situ on the insulating substrate 3 through a "film deposition + scribing / photolithography" process. The concentricity of the electrodes depends entirely on the micron-level precision of the photolithography or machining tool, independent of the assembly method, achieving "self-alignment." Furthermore, both electrodes are naturally located on the same reference plane, solving the coplanarity problem.
[0048] 2. Vertical via interconnect: In conjunction with the integrated substrate, internal vias are used to vertically guide signals to the back side, avoiding damage to the electrode pattern caused by surface soldering.
[0049] 3. Dual Encapsulation and Overcutting Process: The first insulating medium 10 within the insulating trench 5 provides mechanical strength similar to that of the metal electrode and ceramic substrate, ensuring the sharpness and flatness of the electrode edges. The second insulating medium 11 between the insulating substrate 3 and the inner wall of the metal shell 1 acts as a "suspending damper," absorbing stress through its own elastic deformation and blocking the transmission of stress to the internal rigid substrate, thereby ensuring the long-term stability of the electrode's geometric position.
[0050] According to a second aspect of the present invention, a method for manufacturing a vertically interconnected high-precision coplanar capacitive displacement sensor is provided, comprising the following steps: S1. Substrate preparation: Through holes are machined and metallized on a single piece of insulating material; Specifically, alumina ceramic rods are selected, axial through holes are machined, conductive silver paste is filled by vacuum casting and co-fired at high temperature to form an integral insulating substrate with metallized through holes.
[0051] S2, In-situ forming: A functional electrode layer is formed on the front end face of the insulating substrate. The center electrode and the protective ring are separated in-situ through a precision removal process, and the concentricity is directly guaranteed by the processing precision. Specifically, after precision grinding of the substrate's front end face, a titanium / tungsten seed layer and a gold conductive layer are sputtered. Subsequently, high-precision laser etching or diamond cutting tools are used to remove the metal layer in specific areas, and the central electrode and protective ring are separated in situ.
[0052] Key process points: The etching depth is set to be greater than the metal layer thickness, extending 0.05mm to 0.2mm into the insulating substrate. For example... Figure 5As shown, this "overcutting" process not only geometrically eliminates micro-short circuits caused by metal residue, but also provides physical anchoring space for subsequent glue filling.
[0053] S3, rigid filling: fill the divided insulation trenches with a high-hardness rigid material; Specifically, rigid epoxy resin (the first insulating medium) is vacuum-filled into the deep grooves cut out above. After heating and curing, a rough surface grinding is performed to remove excess colloid.
[0054] S4, Flexible Assembly: The insulating substrate is placed into the metal shell, and a low-modulus flexible material is injected into the annular gap between the insulating substrate and the metal shell. Specifically, the prepared core is placed inside a metal shell, and tooling is used to ensure approximate alignment. Liquid silicone rubber (a second insulating medium) is injected into the gap between the core and the shell, and then allowed to cure.
[0055] S5, Overall Coplanarity: The front face of the insulating substrate is uniformly ground.
[0056] Specifically, after all media have fully cured, the sensor is mounted on an ultra-precision grinding machine. The multi-media mixed surface, consisting of the metal shell end face, flexible rubber layer, protective ring, hard resin layer, and central electrode, is uniformly ground and chemically mechanically polished (CMP) until it reaches the optical mirror level (surface roughness Ra < 0.02 μm), forming a completely seamless planar structure.
[0057] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.
Claims
1. A vertically interconnected high-precision coplanar capacitive displacement sensor, characterized in that, include: Metal casing (1); An insulating substrate (3) is disposed inside the metal casing (1); A functional electrode layer (4) is disposed on the front end surface of the insulating substrate (3); An insulating trench (5) is formed on the front end surface of the insulating substrate (3), and the insulating trench (5) divides the functional electrode layer (4) into a concentric central electrode (6) and a protective ring (7). At least two sets of metallized vias (8) are provided, which penetrate the interior of the insulating substrate (3). The center electrode (6) and the protective ring (7) respectively cover and are electrically connected to the top of the corresponding metallized via (8). The signal lead (9) is electrically connected to the metallized via (8).
2. The vertically interconnected high-precision coplanar capacitive displacement sensor as described in claim 1, characterized in that, The interior of the insulating trench (5) is filled with a first insulating medium (10) for supporting the edge of the central electrode (6), the first insulating medium (10) being a high-hardness rigid material; the space between the insulating substrate (3) and the inner wall of the metal shell (1) is filled with a second insulating medium (11) for suspending and fixing the insulating substrate (3), the second insulating medium (11) being a low-modulus flexible material.
3. The vertically interconnected high-precision coplanar capacitive displacement sensor as described in claim 2, characterized in that, The depth of the insulating trench (5) is greater than the thickness of the functional electrode layer (4), and the insulating trench (5) extends to the front end face of the insulating substrate (3) and forms an overcut anchoring structure.
4. The vertically interconnected high-precision coplanar capacitive displacement sensor as described in claim 1, characterized in that, The functional electrode layer (4) includes a seed layer (41) and a main metal layer (42) stacked with the seed layer (41).
5. The vertically interconnected high-precision coplanar capacitive displacement sensor as described in claim 4, characterized in that, The seed layer (41) is a titanium layer or a chromium layer, and the main metal layer (42) is a gold layer or a copper layer.
6. The vertically interconnected high-precision coplanar capacitive displacement sensor as described in claim 2, characterized in that, The first insulating medium (10) is a high-temperature epoxy resin with a Shore hardness of D85 or higher, and the second insulating medium (11) is a low-modulus modified silicone rubber or polyurethane elastomer.
7. The vertically interconnected high-precision coplanar capacitive displacement sensor as described in claim 2, characterized in that, The mixed surface, consisting of the end face of the metal shell (1), the central electrode (6), the protective ring (7), the first insulating medium (10), and the second insulating medium (11), is ground and polished to form a seamless full-plane structure.
8. The vertically interconnected high-precision coplanar capacitive displacement sensor as described in claim 1, characterized in that, The insulating substrate (3) is an integrally formed columnar structure, and the central electrode (6) and the protective ring (7) are metal thin film layers.
9. The vertically interconnected high-precision coplanar capacitive displacement sensor as described in claim 1, characterized in that, The metallized via (8) is formed by filling conductive silver paste with a through hole that penetrates the interior of the insulating substrate (3) using a vacuum casting method and co-firing at high temperature. The signal lead (9) is welded to the bottom surface of the metallized via (8).
10. A method for manufacturing a vertically interconnected high-precision coplanar capacitive displacement sensor according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Substrate preparation: Through holes are machined and metallized on a single piece of insulating material; S2, In-situ forming: A functional electrode layer is formed on the front end face of the insulating substrate. The center electrode and the protective ring are separated in-situ through a precision removal process, and the concentricity is directly guaranteed by the processing precision. S3, rigid filling: fill the divided insulation trenches with a high-hardness rigid material; S4, Flexible Assembly: The insulating substrate is placed into the metal shell, and a low-modulus flexible material is injected into the annular gap between the insulating substrate and the metal shell. S5, Overall Coplanarity: The front face of the insulating substrate is uniformly ground.