A high-precision patch welding method and device for a microwave plate

Abstract

The application provides a microwave plate high-precision patch welding method and device, and the method comprises micro-nano level pretreatment, micron level positioning clamping, layered temperature control welding, low-oxygen inert atmosphere protection, micro stress step cooling solidification and radio frequency performance online closed loop detection. The activity of the welding surface is improved through argon plasma cleaning and inkjet soldering coating, high magnification vision and six-axis piezoelectric platform are used to realize high-precision positioning of ≤±1μm; the core welding area is rapidly heated by high-frequency induction, and the device area is protected by constant temperature hot air, which is matched with nitrogen low-oxygen atmosphere to inhibit oxidation and reduce the void rate of the welding point; the internal stress is eliminated by step cooling, and the quality is detected online by X-ray and radio frequency vector network analysis. The device integrates pretreatment, positioning, welding, cooling, detection and intelligent control modules, and has the advantages of accurate positioning, small thermal shock, low welding stress and high reliability, which can significantly improve the radio frequency performance and service life of the microwave assembly, and is suitable for high-precision, high-consistency automatic micro-assembly of miniature radio frequency devices.

Description

Technical Field

[0001] This invention relates to the field of microwave component micro-assembly technology, and in particular to a high-precision patch welding method and apparatus for microwave boards. Background Technology

[0002] In the micro-assembly of microwave components, the quality of the surface mount soldering between the microwave board and miniature RF devices (filters, power amplifier chips, bare chips, etc.) directly determines the product's RF performance, environmental adaptability, and on-orbit lifespan. Traditional soldering processes suffer from five major defects: low positioning accuracy (conventional visual positioning deviation > ±5μm, easily causing device misalignment, pad bridging, RF path mismatch, and significantly increased high-frequency losses); crude heating methods (failure to distinguish between the solder area and the device body, resulting in large overall temperature differences, causing chip performance drift and substrate warping); open soldering atmosphere (solder joints are prone to oxidation, high void ratio, and poor long-term reliability); lack of gradient cooling control (rapid cooling generates internal stress, leading to substrate micro-cracks and pin detachment); and lagging quality inspection (relying solely on visual inspection, failing to incorporate RF performance into the online closed loop, allowing defective products to flow into later stages, resulting in cost waste). Existing technologies cannot meet the stringent requirements of high precision, low stress, high reliability, and long lifespan for next-generation microwave components. Summary of the Invention

[0003] The purpose of this invention is to provide a high-precision patch welding method and apparatus for microwave boards. Through innovative processes including micro-nano pretreatment, micron-level positioning, layered temperature-controlled welding, low-oxygen inert protection, micro-stress stepped cooling, and online closed-loop radio frequency detection, this invention achieves positioning deviation ≤ ±1μm, solder joint void rate ≤ 3%, extremely low welding stress, and online qualification of radio frequency performance. This solves the problems of insufficient precision, large thermal shock, stress concentration, and delayed detection in traditional processes, and significantly improves the welding quality and consistency of microwave components.

[0004] According to one objective of the present invention, a high-precision patch bonding method for microwave boards is provided, comprising the following steps: S1. Micro-nano-level surface pretreatment for soldering: Argon plasma cleaning is used, and then micro-nano-level halogen-free flux is precisely coated on the solder pad area by inkjet printing. S2, Micron-level positioning and clamping: Device positioning is achieved through high-magnification visual recognition and a six-axis piezoelectric ceramic fine-tuning platform, and micro pre-pressure is applied using a flexible pressure head; S3, Layered Temperature Controlled Soldering: High-frequency induction rapid heating is applied to the core soldering area, and constant-temperature hot air heating is applied to the heat-affected zone protecting the device. S4. Low-oxygen inert atmosphere protection: High-purity nitrogen is introduced into the sealed welding cavity to control the oxygen content of the cavity; S5, Micro-stress stepped cooling and curing: segmented gradient cooling and heat preservation, maintaining an inert atmosphere throughout the process; S6. Online closed-loop testing: Solder joint void rate is detected by X-ray, and radio frequency performance is detected by radio frequency vector network analyzer.

[0005] Furthermore, in step S1, the argon plasma cleaning power is 50. 100W, cleaning time is 30 seconds. 60s; the thickness of the halogen-free flux coating is 5. 15μm, and only covers the area of ​​the pads to be soldered.

[0006] Furthermore, in step S2, the device positioning deviation is ≤ ±1μm; the flexible pressure head is a flexible polyimide pressure head with microgrooves, and the applied pre-pressure is 0.3N. 1.5N.

[0007] Furthermore, in step S3, the heating rate of the core solder area is 10. 20℃ / s, peak temperature is 230℃ 250℃, heat preservation time is 5 10s; the heating temperature of the heat-affected zone of the device is 100℃. 130℃.

[0008] Furthermore, in step S4, the nitrogen purity is ≥99.999%, and the flow rate is 0.8. 2L / min, oxygen content in the sealed welding chamber ≤30ppm.

[0009] Furthermore, in step S5, first use 5 Cool to 150℃ at a rate of 8℃ / s and hold for 10s, then cool at a rate of 2... Cool to room temperature at a rate of 3℃ / s.

[0010] Furthermore, in step S6, the acceptance criteria are: weld void rate ≤ 3%, 2 Insertion loss variation in the 40GHz band is ≤0.08dB, and voltage standing wave ratio is ≤1.2.

[0011] According to another objective of the present invention, the present invention provides a high-precision patch welding device for microwave boards, comprising a micro-nano pretreatment module, a micron-level positioning and clamping module, a layered temperature control welding module, a low-oxygen inert protection module, a micro-stress stepped cooling module, an online detection module, and a total control system; The micro-nano pretreatment module includes an argon plasma cleaning unit and an inkjet flux coating unit. The micron-level positioning and clamping module includes a high-magnification industrial camera and a six-axis piezoelectric ceramic fine-tuning platform. The layered temperature-controlled welding module includes a high-frequency induction heating unit and a constant-temperature hot air heating unit. The online detection module includes an X-ray detector and a radio frequency vector network analyzer.

[0012] Furthermore, the low-oxygen inert protection module includes a sealed welding cavity and a high-purity nitrogen supply system, wherein the oxygen content in the sealed welding cavity is ≤30ppm; the micro-stress stepped cooling module is a programmable temperature control unit.

[0013] Furthermore, the overall control system supports the MODBUS TCP / IP protocol, connects to the MES system, and enables welding parameter control and production data traceability.

[0014] The technical solution of this invention significantly improves the precision and reliability of microwave board patch welding through a synergistic process encompassing micro / nano-level pretreatment, micron-level positioning and clamping, layered temperature-controlled welding, low-oxygen inert protection, micro-stress stepped cooling, and online closed-loop RF testing. Micro / nano-level pretreatment effectively removes surface contaminants and precisely coats flux, avoiding RF path contamination; micron-level positioning significantly reduces the risk of device misalignment, ensuring assembly consistency; layered temperature control and stepped cooling greatly reduce thermal shock and welding stress, preventing device performance drift and substrate deformation; the low-oxygen atmosphere inhibits solder joint oxidation and reduces void ratio; online testing enables dual control of physical quality and RF performance, achieving high-precision, low-stress, and high-reliability welding overall, meeting the stringent requirements of high-end microwave component micro-assembly. Attached Figure Description

[0015] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention; Figure 2 This is a process flow diagram of the method in an embodiment of the present invention; Figure 3 This is a temperature curve diagram of layered temperature control according to an embodiment of the present invention.

[0017] In the diagram: 1. Feeding conveyor belt; 2. Plasma cleaning unit; 3. Inkjet flux coating unit; 4. High-magnification industrial camera; 5. Six-axis piezoelectric ceramic fine-tuning platform; 6. Patch control unit; 7. Sealed welding cavity; 8. High-frequency induction heating unit; 9. Constant temperature hot air heating unit; 10. Programmable temperature control unit; 11. X-ray detector; 12. Radio frequency vector network analyzer; 13. Discharge conveyor belt; 14. MES system; 15. Overall control system. Detailed Implementation

[0018] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0019] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0020] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; and they may refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] Example 1 like Figure 2 As shown, a high-precision patch soldering method for microwave boards includes the following steps: S1. Micro-nano-level surface pretreatment for soldering: Argon plasma cleaning is used to remove oxide layer and contaminants; micro-nano-level halogen-free flux is precisely coated by inkjet printing, covering only the solder pad area and not contaminating the RF path; S2. Micrometer-level visual positioning and flexible clamping: High-magnification visual recognition combined with a six-axis piezoelectric ceramic fine-tuning platform achieves positioning of ≤±1μm; a flexible pressure head with microgrooves is used to apply micro pre-pressure to ensure fit without damaging the device; S3, Layered Temperature Control Welding: The core welding area uses high-frequency induction rapid heating, while the heat-affected zone of the device protection uses constant-temperature hot air low-potential heating to form a gradient temperature control protection device. S4. Low-oxygen inert atmosphere protection throughout the process: High-purity nitrogen is introduced into the sealed cavity to control the oxygen content to ≤30ppm, which inhibits the oxidation of the solder joints and reduces the void rate. S5. Micro-stress stepped cooling and curing: segmented gradient cooling, first fast cooling and then slow cooling and heat preservation, to eliminate the internal stress of the solder joint and the substrate. S6. Online closed-loop testing: including X-ray solder joint quality inspection and RF vector network analysis performance testing. X-ray inspection detects solder joint void rate, and RF vector network analyzer detects insertion loss and VSWR, achieving dual judgment of physical quality and RF performance.

[0022] Specifically, in S1, the cleaning power of the argon atmosphere plasma cleaning is 50. 100W, cleaning time is 30 seconds. 60s; When inkjet printing technology precisely coats halogen-free flux, the flux thickness is 5. 15μm.

[0023] Specifically, in S2, the micron-level positioning clamping uses a flexible polyimide indenter with microgrooves, applying 0.3N. 1.5N micro pre-pressure.

[0024] Specifically, in S3, the heating parameters for the core solder area are: heating rate 10 20℃ / s, peak temperature 230℃ 250℃, heat preservation time 5 10s; the heating temperature of the heat-affected zone of the device is 100℃. A constant temperature of 130℃.

[0025] like Figure 3 The figure shows a schematic diagram of the temperature control curves for layered temperature-controlled soldering according to the present invention. In the figure, the horizontal axis represents time (s) and the vertical axis represents temperature (°C). Curve A is the temperature change curve of the core soldering area, reflecting a rapid heating rate of 10-20°C / s, a peak temperature of 230-250°C, and a holding time of 5-10s. Curve B is the temperature change curve of the heat-affected zone protecting the device, reflecting a constant temperature control state of 100-130°C. Curve C is the temperature change curve of the stepped cooling stage, reflecting the control process of first cooling to 150°C at 5-8°C / s and holding for 10s, and then cooling to room temperature at 2-3°C / s. This figure clearly shows the temperature parameters of layered temperature control and stepped cooling, reflecting the design principle of the present invention to reduce thermal stress and protect micro RF devices.

[0026] Specifically, in step S4, nitrogen gas with a purity ≥99.999% is introduced into the sealed welding cavity at a flow rate of 0.8 kJ / L. 2L / min.

[0027] Specifically, in S5, the micro-stress stepped cooling curing process is as follows: first, at 5... Cool to 150℃ at a rate of 8℃ / s and hold for 10s, then cool at a rate of 2... Cooled to room temperature at a rate of 3℃ / s, maintaining an inert atmosphere throughout the process.

[0028] Specifically, in S6, the online closed-loop detection pass standard is: weld void rate ≤3%, 2 Insertion loss variation in the 40GHz band is ≤0.08dB, and voltage standing wave ratio is ≤1.2.

[0029] like Figure 1 As shown, a high-precision microwave board patch welding device includes a micro / nano pretreatment module, a micron-level positioning and clamping module, a layered temperature-controlled welding module, a low-oxygen inert protection module, a micro-stress stepped cooling module, an online detection module, and a main control system; wherein: The micron-level positioning and clamping module includes a high-magnification industrial camera 4 and a six-axis piezoelectric ceramic fine-tuning platform 5; The layered temperature-controlled welding module includes a high-frequency induction heating unit 8 and a constant-temperature hot air heating unit 9.

[0030] The low-oxygen inert protection module includes a sealed welding chamber 7 and a high-purity nitrogen supply system, which can control the oxygen content inside the chamber to ≤30ppm.

[0031] The online detection module includes X-ray detectors 11 and 2. 40GHz Broadband Radio Frequency Vector Network Analyzer 12.

[0032] The micro-stress stepped cooling module is a programmable temperature control unit 10, which can output segmented gradient cooling curves.

[0033] The main control system 15 supports the MODBUS TCP / IP communication protocol and can be connected to the production line MES system 14 to realize welding parameter control and production data traceability.

[0034] The micro-nano pretreatment module includes an argon plasma cleaning unit 2 and an inkjet flux precision coating unit 3.

[0035] The micron-level positioning and clamping module is equipped with a flexible polyimide microgroove pressure head. The pre-pressure of the flexible polyimide microgroove pressure head is adjustable within a range of 0.3N, controlled by the patch control unit 6. 1.5N.

[0036] The layered temperature-controlled welding and micro-stress stepped cooling curing process is completed entirely in the inert atmosphere of a sealed cavity.

[0037] The device of this invention integrates a feeding conveyor belt 1 and a discharging conveyor belt 13, enabling fully automated assembly line-style chip bonding operations. The method of this invention is suitable for high-precision, low-stress bonding of microwave filters, power amplifier chips, RF bare chips, and microwave boards.

[0038] Example 2 This embodiment is based on embodiment 1 and provides a filter. The method for welding polytetrafluoroethylene (PTFE) microwave plates includes the following steps: Pretreatment: Argon plasma cleaning at 70W for 50 seconds; inkjet printing to coat with 10μm thick halogen-free flux, then air drying at room temperature for 5 minutes. Positioning and clamping: visual positioning deviation ±1μm, flexible polyimide indenter applies 0.6N pre-pressure; Welding atmosphere: Nitrogen flow rate 1.2 1.5L / min, oxygen content 30ppm; Layered welding: The core welding area has a heating rate of 15℃ / s, a peak temperature of 240℃, and a holding time of 7s; the heat-affected zone is kept at a constant temperature of 110℃. Step cooling: Reduce the temperature to 150℃ at a rate of 6℃ / s, hold for 10 seconds, and then reduce the temperature to room temperature at a rate of 2.5℃ / s. Test results: X-ray void ratio ≤ 3% 2.2%; 2 The insertion loss variation at 18GHz is 0.05dB≤0.08dB, and the VSWR is 1.12≤1.15, all of which are qualified.

[0039] This invention achieves a positioning accuracy of ±1μm, meeting the high-precision assembly requirements of micro-devices; employing layered temperature control and stepped cooling significantly reduces thermal shock and welding stress, preventing device performance drift; through low-oxygen atmosphere protection, the solder joint void rate is ≤3%, meeting the long-life requirements of high-reliability products such as satellites; this invention features online closed-loop detection of RF performance, enabling real-time quality control, improving yield, and reducing losses; with high automation integration, it can seamlessly integrate with existing micro-assembly production lines, resulting in low modification costs and short cycles.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-precision patch bonding method for microwave boards, characterized in that, Includes the following steps: S1. Micro-nano-level surface pretreatment for soldering: Argon plasma cleaning is used, and then micro-nano-level halogen-free flux is precisely coated on the solder pad area by inkjet printing. S2, Micron-level positioning and clamping: Device positioning is achieved through high-magnification visual recognition and a six-axis piezoelectric ceramic fine-tuning platform, and micro pre-pressure is applied using a flexible pressure head; S3, Layered Temperature Control Welding: High-frequency induction rapid heating is applied to the core welding area, and constant-temperature hot air heating is applied to the heat-affected zone of the device protection. S4. Low-oxygen inert atmosphere protection: High-purity nitrogen is introduced into the sealed welding cavity to control the oxygen content of the cavity; S5, Micro-stress stepped cooling and curing: segmented gradient cooling and heat preservation, maintaining an inert atmosphere throughout the process; S6. Online closed-loop testing: Solder joint void rate is detected by X-ray, and radio frequency performance is detected by radio frequency vector network analyzer.

2. The high-precision patch welding method for microwave boards according to claim 1, characterized in that, In step S1, the argon plasma cleaning power is 50. 100W, cleaning time is 30 seconds. 60s; the thickness of the halogen-free flux coating is 5. 15μm, and only covers the area of ​​the pad to be soldered.

3. The high-precision patch welding method for microwave boards according to claim 1, characterized in that, In step S2, the device positioning deviation is ≤ ±1μm; the flexible indenter is a flexible polyimide indenter with microgrooves, and the applied pre-pressure is 0.3N. 1.5N.

4. The high-precision patch welding method for microwave boards according to claim 1, characterized in that, In step S3, the heating rate of the core solder area is 10. 20℃ / s, peak temperature is 230℃ 250℃, heat preservation time is 5 10s; the heating temperature of the heat-affected zone of the device is 100℃. 130℃.

5. The high-precision patch welding method for microwave boards according to claim 1, characterized in that, In step S4, the nitrogen purity is ≥99.999%, and the flow rate is 0.

8. 2L / min, oxygen content in the sealed welding chamber ≤30ppm.

6. The high-precision patch welding method for microwave boards according to claim 1, characterized in that, In step S5, first use 5 Cool to 150℃ at a rate of 8℃ / s and hold for 10s, then cool at a rate of 2... Cool to room temperature at a rate of 3℃ / s.

7. The high-precision patch welding method for microwave boards according to claim 1, characterized in that, In step S6, the pass / fail criteria are: weld void rate ≤ 3%, 2 Insertion loss variation in the 40GHz band is ≤0.08dB, and voltage standing wave ratio is ≤1.

2.

8. A high-precision microwave board patch welding device, characterized in that, It includes a micro-nano pretreatment module, a micron-level positioning and clamping module, a layered temperature-controlled welding module, a low-oxygen inert protection module, a micro-stress stepped cooling module, an online detection module, and a total control system; The micro-nano pretreatment module includes an argon plasma cleaning unit and an inkjet flux coating unit. The micron-level positioning and clamping module includes a high-magnification industrial camera and a six-axis piezoelectric ceramic fine-tuning platform. The layered temperature-controlled welding module includes a high-frequency induction heating unit and a constant-temperature hot air heating unit. The online detection module includes an X-ray detector and a radio frequency vector network analyzer.

9. The high-precision microwave board patch welding device according to claim 8, characterized in that, The low-oxygen inert protection module includes a sealed welding cavity and a high-purity nitrogen supply system, wherein the oxygen content in the sealed welding cavity is ≤30ppm; the micro-stress stepped cooling module is a programmable temperature control unit.

10. The high-precision microwave board patch welding device according to claim 8, characterized in that, The overall control system supports the MODBUS TCP / IP protocol, connects to the MES system, and enables welding parameter control and production data traceability.

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