Electrode welding structure for ceramic heater

Abstract

The invention relates to the technical field of semiconductor manufacturing, in particular to an electrode welding structure for a ceramic heater. Comprising a ceramic substrate provided with a pre-embedded conductive member; the electrode stem is connected with the pre-embedded conductive part through the first connecting hole, and the space between the electrode stem and the pre-embedded conductive part is filled with welding flux; and the threaded part is in threaded connection with the inner side of the first connecting hole and is provided with an assembly hole for the threaded part to pass through. The ceramic base body, the electrode stem, the threaded part and other parts are arranged, the welding flux is arranged between the electrode stem and the pre-embedded conductive part, and a coaxial assembling structure in the assembling hole guides the electrode stem and the first connecting hole to be coaxially assembled. The problem that in the prior art, the assembling coaxiality of the electrode stem and the connecting hole is low is solved, and uniform welding seams between the electrode stem and the connecting hole can be filled with welding flux.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor manufacturing, and in particular to an electrode welding structure for a ceramic heater. Background Art

[0002] Chemical Vapor Deposition (CVD) is an extremely critical process in semiconductor manufacturing. By discharging to form plasma gas reactants in the reaction chamber, chemical vapor deposition can stack multiple layers of thin films with different conductivity on the surface of the wafer, thereby completing device manufacturing. The temperature distribution on the wafer surface has a significant impact on the uniformity of thin film growth. In the chamber used to perform the CVD process, ceramic heaters are generally used to heat the wafer and maintain the temperature uniformity of the wafer surface.

[0003] Ceramic heaters are typically designed with a heating element that adjusts the voltage in real time during the CVD process to keep the temperature of the heating surface and the wafer within the specified process temperature range.

[0004] In current equipment, the electrode rod is directly inserted into the connection hole of the ceramic substrate and connected to the heating element via a pre-embedded conductive component. The electrode rod and the pre-embedded conductive component are then connected by brazing. However, this method may cause low coaxiality between the electrode rod and the connection hole, resulting in an uneven weld. When the solder is welded within the weld, it may cause abnormal hot spots at the weld, affecting the temperature uniformity of the heating surface, and thus affecting the temperature uniformity of the wafer surface and the formation of thin films. Summary of the Invention

[0005] In view of this, the present invention provides an electrode welding structure for a ceramic heater to solve the problem of abnormal hot spots caused by low assembly coaxiality.

[0006] The present invention provides an electrode welding structure for a ceramic heater, comprising:

[0007] A ceramic substrate is provided with embedded conductive parts;

[0008] an electrode rod connected to the embedded conductive member through the first connecting hole, wherein solder is filled between the electrode rod and the embedded conductive member;

[0009] a threaded member, screwed onto the inner side of the first connecting hole, and having an assembly hole for the threaded member to pass through;

[0010] The assembly hole has a coaxial assembly structure, and the coaxial assembly structure is suitable for guiding the electrode rod to extend into the first connecting hole, and enables the electrode rod to be coaxially assembled with the first connecting hole.

[0011] This application provides components such as a ceramic matrix, an electrode rod, and a threaded part, and provides solder between the electrode rod and the embedded conductive part. The coaxial assembly structure in the assembly hole guides the electrode rod to be coaxially assembled with the first connecting hole. This solves the problem of low coaxiality between the electrode rod and the connecting hole in the prior art, allowing the solder to be filled in the uniform weld between the electrode rod and the connecting hole, avoiding abnormal hot spots at the weld, thereby ensuring the uniformity of the heating surface temperature, and thus improving the uniformity of the wafer surface temperature and the quality of the thin film generated.

[0012] In an optional embodiment, the coaxiality assembly structure includes:

[0013] The annular raised section is arranged on the side wall of the assembly hole and is coaxial with the assembly hole.

[0014] The present application provides an annular raised section on the inner side wall of the assembly hole as a coaxial assembly structure. The presence of the annular raised section can guide and limit the insertion of the electrode rod, allowing the electrode rod to more accurately remain coaxial with the first connecting hole during the insertion process. This not only improves the accuracy and reliability of assembly, but also ensures that the solder is evenly distributed in the gap between the electrode rod and the connecting hole, enhancing welding strength, reducing contact resistance fluctuations and uneven heating caused by uneven solder filling, and further improving the performance and stability of the ceramic heater.

[0015] In an optional embodiment, the coaxiality assembly structure includes:

[0016] The tapered section is coaxial with the assembly hole and is located on a side of the assembly hole away from the embedded conductive part. The diameter of the tapered section increases as the position changes along the direction from the embedded conductive part to the electrode rod.

[0017] This application places a tapered section on the side of the assembly hole away from the embedded conductive component. The diameter of the tapered section increases as it moves from the embedded conductive component to the electrode rod. This allows for positioning and guiding the electrode rod. When the electrode rod is inserted into the assembly hole, the tapered section automatically adjusts its insertion angle and position, gradually aligning it with the axis of the assembly hole, thereby improving assembly convenience and coaxiality.

[0018] In an optional embodiment, the portion of the electrode rod extending into the assembly hole has a reduced diameter section adapted to the tapered section.

[0019] A tapered section that matches the tapered section is provided at the section of the electrode rod that extends into the assembly hole. The tapered section and the tapered section cooperate with each other to further improve the coaxial assembly effect between the electrode rod and the assembly hole. When the electrode rod is inserted, the tapered section gradually enters the tapered section, and the two are tightly combined, so that the electrode rod is more accurately positioned at the axial center of the assembly hole. This not only enhances the tightness of the connection between the electrode rod and the assembly hole, but also effectively prevents the electrode rod from shifting or shaking during use, ensuring the stability of the welding quality. In addition, this adaptive design also helps to optimize the stress distribution between the electrode rod and the assembly hole, reduce stress concentration caused by factors such as thermal expansion, extend the service life of the electrode welding structure, and ensure the reliability and stability of the ceramic heater in long-term operation.

[0020] In an optional embodiment, the tapered section fits in with the tapered section.

[0021] The present application makes the tapered section fit with the diameter-reducing section, so that the axis of the tapered section is completely aligned with the axis of the diameter-reducing section, and the axis of the electrode rod is aligned with the axis of the connecting hole.

[0022] In an optional embodiment, the coaxiality assembly structure includes:

[0023] a guide groove, provided on a side wall of the assembly hole along an extension direction of the threaded member;

[0024] The electrode rod is provided with a bite structure matched with the guide groove.

[0025] The present application provides a guide groove on the side wall of the assembly hole along the extension direction of the threaded part, and provides an interlocking structure that is compatible with the guide groove on the electrode rod. The cooperation of the guide groove and the interlocking structure can provide clear directional guidance for the insertion of the electrode rod, so that the electrode rod can accurately enter the assembly hole along the guide groove, ensuring the coaxiality of the electrode rod and the assembly hole. This design not only improves the accuracy and efficiency of assembly, but also effectively prevents the electrode rod from colliding or scratching with the wall of the assembly hole due to directional deviation during the insertion process, protects the surface quality of the electrode rod and the assembly hole, and prolongs its service life. In addition, the interlocking structure can also play a certain limiting role after the electrode rod is inserted, preventing the electrode rod from radial displacement during use, ensuring the stability and reliability of the electrode welding structure, and thus ensuring the normal operation of the ceramic heater.

[0026] In an optional embodiment, the solder layer formed by the solder does not exceed one third of the depth of the first connection hole.

[0027] The present application controls the welding layer formed by the solder to not exceed one-third of the hole depth of the first connecting hole. This design can reserve enough space for the thermal expansion of the electrode rod while ensuring good welding strength between the electrode rod and the embedded conductive part. During the operation of the ceramic heater, the electrode rod and other components will undergo thermal expansion due to temperature changes. If too much solder is filled, the expansion of the electrode rod will be restricted, which can easily generate thermal stress and cause cracking of the ceramic matrix or damage to other components. Controlling the welding layer to within one-third of the hole depth not only ensures the reliability of the welding, but also provides sufficient space for the thermal expansion of the electrode rod, reduces the stress concentration caused by uneven thermal expansion, reduces the risk of failure of the ceramic heater under high-temperature working conditions, and improves its overall stability and durability.

[0028] In an optional embodiment, a second connection hole coaxial with the first connection hole is connected between the first connection hole and the embedded conductive member, and an intermediate conductive member is provided in the second connection hole.

[0029] This application provides a second connection hole between the first connection hole and the embedded conductive member, and an intermediate conductive member is positioned within the second connection hole. The introduction of the intermediate conductive member serves as a transition and buffer, dividing the connection between the electrode rod and the embedded conductive member into two sections, reducing assembly difficulty. The intermediate conductive member can better adapt to the internal structure of the ceramic substrate and the position of the embedded conductive member, improving the flexibility and adaptability of the entire electrode welding structure.

[0030] In an optional embodiment, solder is filled between the intermediate conductive member and the embedded conductive member, and a welding layer formed by the solder is filled between the second connection hole and the intermediate conductive member.

[0031] The present application sets solder between the intermediate conductive part and the embedded conductive part, and fills the welding layer formed by the solder between the second connecting hole and the intermediate conductive part. This design firmly connects the intermediate conductive part and the embedded conductive part together through solder, ensuring the electrical connectivity and mechanical stability between the two. The solder filled between the second connecting hole and the intermediate conductive part can effectively fill the tiny gap between the two, improve the tightness and conductivity of the connection, and reduce the contact resistance. In addition, the solder layer can also play a certain buffering role, to a certain extent, alleviate the stress caused by the difference in thermal expansion coefficient, reduce mutual extrusion and damage between components, and improve the reliability and durability of the electrode welding structure, thereby ensuring that the ceramic heater can operate stably during long-term use.

[0032] In an optional embodiment, the diameter of the electrode rod is greater than the diameter of the intermediate conductive member, and the diameter of the intermediate conductive member is greater than the diameter of the embedded conductive member.

[0033] In this application, the diameter of the electrode rod is designed to be larger than that of the intermediate conductive member, and the diameter of the intermediate conductive member is designed to be larger than that of the embedded conductive member, forming a stacked structure. This effectively connects the electrode rod, the intermediate conductive member, and the embedded conductive member, while also covering the intermediate conductive member and the embedded conductive member with the electrode rod, preventing them from aging and oxidation due to contact with the outside world. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 This is a schematic structural diagram of an embodiment of the present invention;

[0036] Figure 2 This is a partially enlarged schematic diagram of point A in Example 1 of the present invention;

[0037] Figure 3 This is a schematic diagram of the structure of a first threaded member according to an embodiment of the present invention;

[0038] Figure 4 This is a schematic cross-sectional view of a first threaded member according to an embodiment of the present invention;

[0039] Figure 5 This is a schematic diagram of the assembly of the tapered section and the tapered section according to an embodiment of the present invention;

[0040] Figure 6 This is a schematic structural diagram of a second threaded member according to an embodiment of the present invention;

[0041] Figure 7 This is a schematic cross-sectional view of a second threaded member according to an embodiment of the present invention;

[0042] Figure 8 This is a schematic diagram of the position of the guide groove according to an embodiment of the present invention;

[0043] Figure 9 This is a schematic structural diagram of a third threaded member according to an embodiment of the present invention;

[0044] Figure 10 This is an explosion diagram of an embodiment of the present invention;

[0045] Figure 11 This is a schematic diagram of the assembly of the third threaded component according to an embodiment of the present invention.

[0046] Description of reference numerals:

[0047] 1. Ceramic substrate; 2. Embedded conductive part; 3. Ceramic tube; 4. Electrode rod; 5. First connecting hole; 6. Solder; 7. Heating component; 8. Threaded part; 9. Assembly hole; 10. Notch; 11. Annular raised section; 12. Conical section; 13. Reduced diameter section; 14. Guide groove; 15. Engaging structure; 16. Second connecting hole; 17. Intermediate conductive part; 18. First step surface; 19. Second step surface. DETAILED DESCRIPTION

[0048] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0049] Chemical vapor deposition (CVD) is a critical process in semiconductor manufacturing. By using discharge to form plasma-like gaseous reactants in a reaction chamber, CVD can stack multiple layers of thin films with varying conductivity on the surface of a wafer, thereby completing device manufacturing. The temperature distribution on the wafer surface significantly affects the uniformity of thin film growth. Therefore, ceramic heaters are installed in the chamber used to perform the CVD process to heat the wafer and maintain temperature uniformity across the wafer surface.

[0050] To achieve heating and maintain a certain degree of wafer stability, ceramic heaters are typically designed with wafer electrodes and heating elements. The wafer electrodes and the RF electrode at the top of the chamber form a capacitor-like field, ionizing the process gas flowing into the chamber into a plasma. During the CVD process, the heating element adjusts the voltage in real time to maintain the temperature of the disk and wafer within the specified process temperature range.

[0051] However, the existing electrode structure for connecting the wafer electrode and the heating component has a low coaxiality between the components, resulting in uneven welds. The uneven welds on the radial cross section cause uneven distribution of the solder, which is not distributed in a uniform ring shape, but in an eccentric ring shape, resulting in reduced welding strength and difficult to control contact resistance. At the same time, the uneven welds will lead to abnormal hot spots, which will damage the uniformity of the heating surface temperature. On the other hand, the dimensional design of the various components in the existing electrode structure requires very high precision in the coaxial assembly of the invisible components used for positioning in the ceramic heater, which increases the difficulty of the process and increases the risk of unreliable conductivity.

[0052] In short, the electrode structure design of the existing ceramic heater makes it difficult to achieve coaxial assembly of the workpiece, resulting in uneven weld filling, reduced bonding strength, difficult to control contact resistance, and the presence of undesirable hot spots.

[0053] In terms of technology, the electrode structure of existing ceramic heaters requires precise positioning on the ceramic substrate to find the electrode access point. This process is difficult and can easily cause poor contact.

[0054] The following combination Figures 1 to 11 , describing embodiments of the present invention.

[0055] According to an embodiment of the present invention, Figures 1 to 11 As shown, the present invention provides an electrode welding structure for a ceramic heater. The ceramic heater is installed inside a chamber of a semiconductor process machine during a CVD process, and a wafer is placed on it and heated. It includes:

[0056] The ceramic base 1 is provided with embedded conductive members 2. The ceramic heater has a circular plate-shaped ceramic base 1. One side of the ceramic base 1 is a heating surface for heating the wafer, and the other side is a back surface. The back surface of the ceramic base 1 is connected to a hollow ceramic tube 3, which is connected to the machine. The material of the ceramic tube 3 is preferably the same as that of the ceramic base 1.

[0057] The electrode rod 4 is connected to the embedded conductive member 2 through the first connecting hole 5, and the space between the electrode rod 4 and the embedded conductive member 2 is filled with solder 6;

[0058] The ceramic substrate 1 has a parallel heating element 7 and a wafer electrode (not shown). Both are connected to the embedded conductive element 2 and are powered by the external circuit through the electrode rod 4. The heating element 7 is an electrically heated resistive heating element, obtained by winding a heating wire or heating plate into a spiral or bending it flat. The embedded conductive element 2 is provided at each end as a conductive element to form an electrical connection. Before the electrode rod 4 is provided, the embedded conductive element 2 is exposed through the first connection hole 5 in the ceramic substrate 1.

[0059] The threaded member 8 is screwed onto the inner side of the first connecting hole 5 and has an assembly hole 9 for the threaded member 8 to pass through; the opening of the first connecting hole 5 is located on the back side of the base. The first connecting hole 5 has an internal thread section, and the outer side wall of the threaded member 8 has an external thread section and a smooth section. The external thread section is screwed onto the internal thread section of the first connecting hole 5, and the smooth section of the threaded member 8 extends out of the ceramic base 1. When installing the threaded member 8, the threaded member 8 can be screwed into the first connecting hole 5 by clamping the smooth section. A notch 10 can be provided on the end face of the threaded member 8 away from the embedded conductive member 2. Several notches 10 can be symmetrically or evenly distributed axially. There are no special requirements for their shape. In order to facilitate the screwing and assembly of the threaded member 8, a symmetrically distributed rectangular structure is preferred.

[0060] The assembly hole 9 has a coaxial assembly structure, which is suitable for guiding the electrode rod 4 to extend into the first connecting hole 5 and allowing the electrode rod 4 to be coaxially assembled with the first connecting hole 5 .

[0061] like Figure 2 As shown, the heating component 7, the wafer electrode, and the embedded conductive member 2 can be pre-embedded in the ceramic powder when the ceramic substrate 1 is formed, and then formed by co-firing. Since the ceramic heater needs to operate at a high temperature for a long time in the semiconductor process, there is thermal stress release due to the different thermal expansion coefficients between different materials. Therefore, the material of the heating component 7, the material of the wafer electrode, and the material of the embedded conductive member 2 are preferably materials with a thermal expansion coefficient close to that of the ceramic substrate 1.

[0062] The material of the ceramic substrate 1 is not particularly specified. In the process of development of this technical field, the ceramic substrate 1 is designed mainly with materials such as aluminum nitride, aluminum oxide, and silicon nitride. The materials of the heating component 7, the wafer electrode, and the embedded conductive part 2 can preferably be refractory metal materials with a thermal expansion coefficient similar to that of the above-mentioned ceramic materials. The difference in thermal expansion coefficient between the two is preferably less than 5ppm / k, and further preferably less than 1ppm / k. In the process of development of this technical field, the metal materials suitable for the above requirements are preferably molybdenum, tungsten, titanium, etc. The heating wire or heating belt made of metal material is designed as a specific continuous structure to achieve the purpose of uniform heating.

[0063] The electrode rod 4 and embedded conductive member 2 form the conductive portion. The ceramic substrate has one or more pairs of conductive portions depending on functional requirements, with at least one pair forming a circuit with positive and negative poles. The conductive portion is connected to the heating element 7. The electrode rod 4 extends from the back of the ceramic base 1 through the hollow ceramic tube 3 and connects to the external circuit, supplying power to the heating element 7. The threaded member 8 mechanically secures the internally threaded first connection hole 5 with an external thread, and partially covers the electrode rod 4.

[0064] The coaxial assembly structure can guide the coaxial assembly of the electrode rod 4 and the first connecting hole 5. During welding, the solder 6 liquefies and is evenly distributed in a ring shape and covers the outer wall of the electrode rod 4, thereby avoiding the generation of abnormal hot spots.

[0065] The present application provides components such as a ceramic substrate 1, an electrode rod 4, and a threaded member 8, and provides a solder 6 between the electrode rod 4 and the embedded conductive member 2. The coaxial assembly structure in the assembly hole 9 guides the coaxial assembly of the electrode rod 4 and the first connecting hole 5. This solves the problem of low coaxiality between the electrode rod 4 and the connecting hole in the prior art, allowing the solder 6 to be filled in the uniform weld seam on the outer wall of the electrode rod 4, avoiding abnormal hot spots at the weld, thereby ensuring the uniformity of the heating surface temperature, and further facilitating improved wafer surface temperature uniformity and thin film production quality.

[0066] In an optional embodiment, as Figures 3 and 4 As shown, the coaxiality assembly structure includes:

[0067] An annular raised section 11 is provided on the side wall of the assembly hole 9 and is coaxial with the assembly hole 9. The annular raised section 11 can form a tight fit with the electrode rod 4, and the clearance between the annular raised section 11 and the electrode rod 4 is preferably between 0.15-0.5 mm, and more preferably between 0.15-0.3 mm. The guidance and tightening of the annular raised section 11 improves the coaxiality between the electrode rod 4 and the first connection hole 5. The first connection hole 5 may have an internally threaded section and a smooth section, with the smooth section of the first connection hole 5 communicating between the internally threaded section of the first connection hole 5 and the embedded conductive member 2. The outer wall of the threaded member 8 has an externally threaded section and a smooth section, with the externally threaded section being threadedly connected to the internally threaded section of the first connection hole 5, and the smooth section of the threaded member 8 extending from the ceramic substrate 1. The solder 6 is positioned so that when the threaded member 8 is installed, it can be screwed into the first connection hole 5 by clamping the smooth section. The end surface of the threaded member 8 facing away from the embedded conductive member 2 may be provided with a notch 10. Several notches 10 may be symmetrically or evenly distributed axially. Their shape is not particularly critical; to facilitate the screwing and assembly of the threaded member 8, a symmetrically distributed rectangular structure is preferred. The smooth section of the first connecting hole 5 is larger than the electrode rod 4 and is connected to the electrode rod 4 by brazing. The radial gap between the smooth section of the first connecting hole 5 and the electrode rod 4 serves as a weld seam during welding.

[0068] The present application provides an annular raised section 11 on the inner sidewall of the assembly hole 9 as a coaxial assembly structure. The presence of the annular raised section 11 can guide and limit the insertion of the electrode rod 4, allowing the electrode rod 4 to more accurately maintain coaxiality with the first connection hole 5 during insertion. This not only improves the accuracy and reliability of assembly, but also ensures that the solder 6 is evenly distributed in the gap between the electrode rod 4 and the smooth section of the connection hole, enhancing weld strength and reducing contact resistance fluctuations and uneven heating caused by uneven filling of the solder 6, further improving the performance and stability of the ceramic heater.

[0069] In an optional embodiment, as Figures 5 to 7 As shown, the coaxiality assembly structure includes:

[0070] The tapered section 12 is coaxial with the mounting hole 9 and located on the side of the mounting hole 9 away from the embedded conductive component 2. The diameter of the tapered section 12 increases as it moves from the embedded conductive component 2 to the electrode rod 4. The tapered section 12 can be part of the mounting hole 9. Alternatively, it can be considered connected to one end of the mounting hole 9, forming a tapered taper from the tapered section 12 to the mounting hole 9.

[0071] The present application improves the process control level during brazing by improving the assembly coaxiality between components. Therefore, the key point is to use the inner wall of the threaded member 8 to guide the assembly of the electrode rod 4.

[0072] like Figure 4 FIG. 1 is a longitudinal cross-sectional view of a threaded member 8 having a tapered section 12. The inner wall of the threaded member 8 is a tapered section 12 having a gradually tightening guide groove-like structure.

[0073] In this application, the tapered section 12 is positioned on the side of the assembly hole 9 away from the embedded conductive member 2. The diameter of the tapered section 12 increases with position along the direction from the embedded conductive member 2 to the electrode rod 4. This allows for positioning and guiding the electrode rod 4. When the electrode rod 4 is inserted into the assembly hole 9, the tapered section 12 automatically adjusts the insertion angle and position of the electrode rod 4, gradually aligning it with the axis of the assembly hole 9, thereby improving assembly convenience and coaxiality.

[0074] In an optional embodiment, the portion of the electrode rod 4 that extends into the assembly hole 9 has a tapered section 13 that mates with the tapered section 12. The diameter of the tapered section 12 is slightly larger than the minor diameter of the electrode rod 4. The electrode rod 4 is designed with a corresponding tapered diameter. Guided by the tapered section 12, the electrode rod 4 can easily pass through the threaded member 8.

[0075] A narrowing section 13 that matches the tapered section 12 is provided at the section where the electrode rod 4 extends into the assembly hole 9. The narrowing section 13 cooperates with the tapered section 12 to further improve the coaxial assembly effect between the electrode rod 4 and the assembly hole 9. When the electrode rod 4 is inserted, the narrowing section 13 gradually enters the tapered section 12, and the two are tightly combined, so that the electrode rod 4 is more accurately positioned at the axial center position of the assembly hole 9. This not only enhances the tightness of the connection between the electrode rod 4 and the assembly hole 9, but also effectively prevents the electrode rod 4 from shifting or shaking during use, thereby ensuring the stability of the welding quality. In addition, this adaptive design also helps to optimize the stress distribution between the electrode rod 4 and the assembly hole 9, reduce stress concentration caused by factors such as thermal expansion, extend the service life of the electrode welding structure, and ensure the reliability and stability of the ceramic heater in long-term operation.

[0076] In an optional embodiment, as Figure 5 As shown, the tapered section 12 fits in with the tapered section 13 .

[0077] In this application, the tapered section 12 is fitted with the tapered section 13 , so that the axis of the tapered section 12 is completely aligned with the axis of the tapered section 13 , and the axis of the electrode rod 4 is aligned with the axis of the first connecting hole 5 .

[0078] The electrode rod 4 fits tightly against the threaded member 8 at the tapered section 12 at the large diameter. At the small diameter, the electrode rod 4 abuts the bottom end of the first connecting hole 5 (this can be achieved by applying pressure to the electrode rod 4 using a press during assembly), and solder 6 is filled between the electrode rod 4 and the embedded conductive member 2, or between the electrode rod 4 and the assembly hole 9. The first connecting hole 5 may have an internal threaded section. The outer wall of the threaded member 8 includes an external threaded section and a smooth section. The external threaded section is screwed to the internal threaded section of the first connecting hole 5, and the end face of the threaded member 8 abuts against the bottom surface of the first connecting hole 5. The smooth section of the threaded member 8 extends out of the ceramic substrate 1. The assembly hole 9 is larger than the electrode rod 4 and is connected to the electrode rod 4 by brazing. The radial gap between the small diameter of the assembly hole 9 and the electrode rod 4 can serve as a weld seam during welding. The weld seam is filled with solder 6 after brazing, thereby improving the bonding strength.

[0079] In an optional embodiment, as Figures 8 to 11 As shown, the coaxiality assembly structure includes:

[0080] A guide groove 14 is provided on the side wall of the assembly hole 9 along the extension direction of the screw member 8;

[0081] The electrode rod 4 is provided with an engaging structure 15 adapted to the guide groove 14 .

[0082] like Figure 6The figure shows a longitudinal cross-sectional view of a threaded member 8 with a guide groove 14. The guide groove 14 is a through groove. The engaging structure 15 can be provided on the electrode rod 4 as a protruding guide rail that matches the guide groove 14, or it can be a slide rail. The protruding guide rail can be a long strip structure.

[0083] Alternatives, such as Figure 9 As shown, the guide groove 14 can be provided on the electrode rod 4 , and the engaging structure 15 can be provided on the side wall of the assembly hole 9 .

[0084] By designing the guide groove 14 , the electrode rod 4 can achieve precise axis positioning, thereby improving positioning accuracy.

[0085] The present application provides a guide groove 14 on the side wall of the assembly hole 9 along the extension direction of the threaded member 8, and provides an interlocking structure 15 that matches the guide groove 14 on the electrode rod 4. The cooperation between the guide groove 14 and the interlocking structure 15 can provide clear directional guidance for the insertion of the electrode rod 4, so that the electrode rod 4 can accurately enter the assembly hole 9 along the guide groove 14, ensuring the coaxiality of the electrode rod 4 and the assembly hole 9. This design not only improves the accuracy and efficiency of assembly, but also effectively prevents the electrode rod 4 from colliding or scratching with the wall of the assembly hole 9 due to directional deviation during the insertion process, thereby protecting the surface quality of the electrode rod 4 and the assembly hole 9 and extending its service life. In addition, the interlocking structure 15 can also play a certain limiting role after the electrode rod 4 is inserted, preventing the electrode rod 4 from radial displacement during use, ensuring the stability and reliability of the electrode welding structure, and thus ensuring the normal operation of the ceramic heater.

[0086] In an optional embodiment, the solder layer formed by the solder 6 does not exceed one third of the depth of the first connecting hole 5 .

[0087] The present application controls the welding layer formed by the solder 6 to not exceed one-third of the depth of the first connecting hole 5. This design can reserve enough space for the thermal expansion of the electrode rod 4 under the premise of ensuring good welding strength between the electrode rod 4 and the embedded conductive part 2. During the operation of the ceramic heater, the electrode rod 4 and other components will undergo thermal expansion due to temperature changes. If the solder 6 is filled too much, the expansion of the electrode rod 4 will be restricted, and thermal stress will easily be generated, causing the ceramic matrix 1 to crack or other components to be damaged. After the solder 6 is liquefied, it will coat the outer wall of the electrode rod 4, and the welding layer will be controlled within one-third of the hole depth, which not only ensures the reliability of the welding, but also provides sufficient space for the thermal expansion of the electrode rod 4, reduces the stress concentration caused by uneven thermal expansion, reduces the risk of failure of the ceramic heater under high-temperature working conditions, and improves its overall stability and durability.

[0088] In an optional embodiment, a second connection hole 16 coaxial with the first connection hole 5 is connected between the first connection hole 5 and the embedded conductive component 2 , and an intermediate conductive component 17 is disposed in the second connection hole 16 .

[0089] This application provides a second connection hole 16 between the first connection hole 5 and the embedded conductive member 2, and an intermediate conductive member 17 is disposed within the second connection hole 16. The introduction of intermediate conductive member 17 serves as a transition and buffer, dividing the connection between the electrode rod 4 and the embedded conductive member 2 into two sections, thus reducing assembly difficulty. Intermediate conductive member 17 can better adapt to the internal structure of the ceramic substrate 1 and the position of the embedded conductive member 2, thereby improving the flexibility and adaptability of the entire electrode welding structure.

[0090] The intermediate conductive member 17 is connected to the embedded conductive member 2 in the ceramic substrate 1 and exists in the ceramic substrate 1 after assembly. Figure 2 As shown, the ceramic substrate 1 is formed with a first connection hole 5 and a second connection hole 16 in sequence from the back side of the substrate to the heating surface. The diameter of the first connection hole 5 is larger than the diameter of the second connection hole 16. A first step surface 18 on the first connection hole 5 is located between the first connection hole 5 and the second connection hole 16. The portion of the screw member 8 inserted into the ceramic substrate 1 can abut against the first step surface 18 of the first connection hole 5.

[0091] In an optional embodiment, as Figure 10 As shown, solder 6 is filled between the intermediate conductive member 17 and the embedded conductive member 2 , and a welding layer formed by the solder 6 is filled between the second connection hole 16 and the intermediate conductive member 17 .

[0092] The present application sets solder 6 between the intermediate conductive part 17 and the embedded conductive part 2, and fills the welding layer formed by the solder 6 between the second connecting hole 16 and the intermediate conductive part 17. This design firmly connects the intermediate conductive part 17 and the embedded conductive part 2 together through the solder 6, ensuring the electrical connectivity and mechanical stability between the two. The solder 6 filled between the second connecting hole 16 and the intermediate conductive part 17 can effectively fill the tiny gap between the two, improve the tightness and conductivity of the connection, and reduce the contact resistance. In addition, the layer of solder 6 can also play a certain buffering role, to a certain extent, relieve the stress caused by the difference in thermal expansion coefficient, reduce mutual extrusion and damage between components, and improve the reliability and durability of the electrode welding structure, thereby ensuring that the ceramic heater can operate stably during long-term use.

[0093] In an optional embodiment, the diameter of the electrode rod 4 is greater than the diameter of the intermediate conductive member 17 , and the diameter of the intermediate conductive member 17 is greater than the diameter of the embedded conductive member 2 .

[0094] In this application, the diameter of the electrode rod 4 is designed to be larger than that of the intermediate conductive member 17, and the diameter of the intermediate conductive member 17 is designed to be larger than that of the embedded conductive member 2, forming a stacked structure. This effectively connects the electrode rod 4, the intermediate conductive member 17, and the embedded conductive member 2, while also covering the intermediate conductive member 17 and the embedded conductive member 2 via the electrode rod 4, preventing them from aging and oxidation due to contact with the outside world.

[0095] In this embodiment, the diameter of the electrode rod 4 should be larger than that of the intermediate conductive member 17, which in turn should be larger than that of the embedded conductive member 2. The diameter of the first connection hole 5 is larger than that of the electrode rod 4, and the diameter of the second connection hole 16 is larger than that of the intermediate conductive member 17. Through the design of the stacked structure, the electrode rod 4 overlies the intermediate conductive member 17, which in turn overlies the embedded conductive member 2. This ensures reliable electrical connection between the different structures and optimizes positioning and drilling accuracy even when slight errors exist on the ceramic substrate 1, allowing for minor positioning errors.

[0096] The following will further explain the structural design and assembly method in conjunction with the connection method of this embodiment:

[0097] like Figure 8 As shown, the electrode structure connection method of this embodiment includes the following steps:

[0098] S1, a first connecting hole 5 and a second connecting hole 16 are formed in sequence on the ceramic base 1, and the embedded conductive part 2 is exposed. The second connecting hole 16 can be designed as a cylindrical light hole, and its diameter is larger than the embedded conductive part 2 to ensure that the embedded conductive part 2 can be completely exposed. The shape of the embedded conductive part 2 is not particularly specified, and can be designed as a spherical structure, a block structure, or a columnar body, preferably a columnar body. The depth of the second connecting hole 16 is preferably tangent to or flush with the embedded conductive part 2, for example, flush with the upper surface of the columnar embedded conductive part 2. There is a second step surface 19 on the second connecting hole 16 between the second connecting hole 16 and the embedded conductive part 2, and the intermediate conductive part 17 abuts against the second step surface 19 of the second connecting hole 16.

[0099] S2, place the solder 6 on the second step surface 19 of the second connecting hole 16, and then place the intermediate conductive part 17. The shape of the intermediate conductive part 17 is not specifically specified, and its shape is designed according to the shape of the connecting hole. In this embodiment, the shape of the intermediate conductive part 17 is a columnar body, and its diameter is designed to be slightly smaller than the second connecting hole 16, and the height is preferably flush with the second step surface 19. Since the size of the intermediate conductive part 17 is slightly smaller than the second connecting hole 16, there is a gap between the two. The existence of the gap effectively alleviates the phenomenon that the thermal stress generated by the mismatch of thermal expansion coefficients between different materials leads to mutual extrusion and structural damage. The gap can also serve as a weld between the second connecting hole 16 and the intermediate conductive part 17. It should be noted that the size of the intermediate conductive part 17 is slightly smaller than the second connecting hole 16, which can ensure the radial coaxiality of the assembly of the intermediate conductive part 17 and the second connecting hole 16 without affecting the temperature uniformity.

[0100] S3. Form a first connection hole 5 in the ceramic substrate 1. The diameter of the first connection hole 5 is designed to be slightly larger than the diameter of the intermediate conductive member 17 to ensure that the intermediate conductive member 17 is fully exposed. The first connection hole 5 extends from the back surface of the ceramic substrate 1 to the first step surface 18 of the first connection hole 5.

[0101] S4: Solder 6 is placed on the first stepped surface 18 of the first connecting hole 5, followed by the screw 8. The external threaded section of the screw 8 is screwed into the internal threaded section of the first connecting hole 5, and once in place, it abuts against the first stepped surface 18 of the first connecting hole 5. The electrode rod 4 is inserted, guided by the screw 8. The shape of the electrode rod 4 is not specifically specified; it is designed based on the shape of the connecting hole. In this embodiment, the electrode rod 4 is cylindrical, with a diameter slightly smaller than that of the first connecting hole 5. The insertion depth is preferably flush with the first stepped surface 18 of the first connecting hole 5. This creates a gap between the electrode rod 4 and the first connecting hole 5.

[0102] S5, welding the above structures together by brazing to form a welding layer at the gap.

[0103] The material of the electrode rod 4 is not specifically specified in this application, but is based on the operating requirements of the ceramic heater. Considering the operating environment of the ceramic heater, a metal with low electrical resistance, a melting point above the operating temperature, and high-temperature oxidation resistance should be selected. Nickel, copper, titanium, and the like are preferred. The material of the threaded member 8, which directly contacts the ceramic substrate 1, is preferably a metal with a thermal expansion coefficient close to that of the ceramic substrate 1, such as molybdenum, tungsten, or titanium. Other metals with low thermal expansion coefficients, such as Kovar, are also acceptable.

[0104] The composition of the solder 6 in this application is not specifically specified, and nickel-based solder 6, gold-based solder 6, silver-copper-nickel solder 6, etc. can be used. Its properties can be in the form of sheets, wires, or solder paste. After the solder 6 on the first step surface 18 of the first connecting hole 5 and the second step surface 19 of the second connecting hole 16 melts, it fills the gap at the step surface, and this gap is designed to be a free gap. The melted solder 6 also fills the gap between the intermediate conductive part 17 and the ceramic substrate 1, and between the electrode rod 4 and the threaded part 8. The amount of solder 6 used is preferably to completely fill the gap between the intermediate conductive part 17 and the ceramic substrate 1, but the gap between the electrode rod 4 and the threaded part 8 does not exceed 1 / 3 of the maximum connection hole depth. In this way, the remaining free gap is used as a reserved space for the expansion of the electrode rod 4 inserted into the disk body, reducing the cracking of the substrate caused by different thermal expansion coefficients. The solder 6 layer in the gap between the intermediate conductive part 17 and the ceramic substrate 1 can serve as a thermal expansion buffer layer between the intermediate conductive part 17 and the ceramic substrate 1. Since the material of the intermediate conductive member 17 is optimally designed, the use of the welding layer as a buffer layer can maintain the conductive function while ensuring that the disk body does not crack.

[0105] The electrode structure design of this embodiment is designed for the threaded fasteners. The small gap at the contact point between the inner wall of the threaded member 8 and the electrode rod 4 maximizes the coaxiality of the assembly link of the electrode rod 4 inserted into the ceramic substrate 1, and ensures the uniformity of the gap filled by the solder 6. It avoids the difficulty in controlling the contact resistance and the generation of bad hot spots caused by the uneven filling of the gap with the solder 6. The stacking design between the electrode rod 4, the intermediate conductive part 17, and the embedded conductive part 2 maximizes the realization of the conductive function of the conductive part. The solder 6 layer between the intermediate conductive part 17 and the ceramic substrate 1, and the free gap between the electrode rod 4 and the first connecting hole 5 reduce the phenomenon of substrate cracking caused by the mismatch of thermal expansion coefficients between different materials, and ensure good electrical conductivity.

[0106] The diameter of the embedded conductive member 2 of the present application is smaller than that of the intermediate conductive member 17, and the diameter of the intermediate conductive member 17 is smaller than that of the electrode rod 4. Through stacking and assembly, the conductive part is guaranteed to be located on the conductive path to the greatest extent, thereby improving circuit reliability.

[0107] The present application includes a stacked assembly design, and the inner wall of the threaded member 8 has a reduced diameter design. By reducing the diameter, the electrode rod 4 is fixed to the axial center position of the conductive part, the assembly concentricity of the workpiece is improved, and the reserved gap is controlled uniformly.

[0108] The present application includes a stacked assembly design, where the inner wall of the threaded member 8 is guided by a tapered section 12, which fits in with the large diameter of the electrode rod 4, improving the assembly concentricity of the workpiece and ensuring uniform clearance control.

[0109] The present application includes a stacked assembly design in which a guide groove is provided on the inner wall of the screw member 8. The guide groove is precisely docked with the slide rail on the electrode rod 4 to improve the assembly concentricity of the workpiece and to control the reserved gap to be uniform.

[0110] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention. Such modifications and variations are all within the scope defined by the appended claims.

Claims

1. An electrode welding structure for a ceramic heater, characterized in that: include: A ceramic substrate (1) is provided with a pre-embedded conductive member (2); An electrode rod (4) is connected to the embedded conductive part (2) through a first connection hole (5), and solder (6) is filled between the electrode rod (4) and the embedded conductive part (2); a threaded member (8) screwed onto the inner side of the first connecting hole (5) and having an assembly hole (9) for the threaded member (8) to pass through; The assembly hole (9) has a coaxial assembly structure, and the coaxial assembly structure is suitable for guiding the electrode rod (4) to extend into the first connection hole (5), and enables the electrode rod (4) and the first connection hole (5) to be coaxially assembled.

2. The electrode welding structure for a ceramic heater according to claim 1, characterized in that: The coaxiality assembly structure includes: An annular raised section (11) is provided on the side wall of the assembly hole (9) and is coaxial with the assembly hole (9).

3. The electrode welding structure for a ceramic heater according to claim 1, characterized in that: The coaxiality assembly structure includes: The conical section (12) is coaxial with the assembly hole (9) and is located on a side of the assembly hole (9) away from the embedded conductive part (2). The diameter of the conical section (12) increases as the position of the conical section (12) changes along the direction from the embedded conductive part (2) to the electrode rod (4).

4. The electrode welding structure for a ceramic heater according to claim 3, characterized in that: The portion of the electrode rod (4) extending into the assembly hole (9) has a diameter-reducing section (13) adapted to the tapered section (12).

5. The electrode welding structure for a ceramic heater according to claim 4, characterized in that: The tapered section (12) is fitted with the diameter-reducing section (13).

6. The electrode welding structure for a ceramic heater according to claim 1, characterized in that: The coaxiality assembly structure includes: A guide groove (14) is provided on a side wall of the assembly hole (9) along an extension direction of the threaded member (8); The electrode rod (4) is provided with an engaging structure (15) adapted to the guide groove (14).

7. The electrode welding structure for a ceramic heater according to claim 1, characterized in that: The solder layer formed by the solder (6) does not exceed one third of the depth of the first connecting hole (5).

8. The electrode welding structure for a ceramic heater according to claim 1, characterized in that: A second connection hole (16) coaxial with the first connection hole (5) is connected between the first connection hole (5) and the embedded conductive member (2), and an intermediate conductive member (17) is provided in the second connection hole (16).

9. The electrode welding structure for a ceramic heater according to claim 8, characterized in that: Solder (6) is filled between the intermediate conductive part (17) and the embedded conductive part (2), and a welding layer formed by the solder (6) is filled between the second connection hole (16) and the intermediate conductive part (17).

10. The electrode welding structure for a ceramic heater according to claim 8, characterized in that: The diameter of the electrode rod (4) is greater than the diameter of the intermediate conductive part (17), and the diameter of the intermediate conductive part (17) is greater than the diameter of the embedded conductive part (2).

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