Method for assembling and connecting microminiature radio frequency connector on high-density antenna array plane

Abstract

The invention relates to the technical field of radar electronic equipment antenna feeder subsystem manufacturing, in particular to a method for assembling a microminiature radio frequency connector on a high-density antenna array plane, which comprises the following steps of: S1, manufacturing a light antenna reflecting plate with step through holes uniformly distributed on the surface and weldable plating layers pre-plated in the holes; s2, manufacturing a metalized tapered slot Vivaldi obliquely polarized antenna unit with a blind hole and a weldable coating pre-plated in the hole; s3, a welding tool which is provided with an elastic device and has a shape maintaining function is manufactured; s4, designing a special solder ring pre-coated with a soldering flux; and S5, welding a microminiature radio frequency connector on the reflecting plate, and simultaneously realizing high-quality interconnection of the connector and the antenna array through one-time welding, thereby solving the problems of array surface deformation and poor welding in the process of assembling the microminiature (SMP / SSMP) radio frequency connector on the existing antenna array surface.

Description

Technical Field

[0001] The invention relates to the technical field of manufacturing antenna feed subsystems of radar electronic equipment, and in particular to a method for assembling a miniature radio frequency connector on a high-density antenna array. Background Art

[0002] Modern radar electronic equipment has greatly increased its performance requirements. On the one hand, the operating frequency band of RF antennas has developed from meter waves and millimeter waves to C, X, Ku and even higher; on the other hand, the volume and quality requirements are getting smaller and smaller, especially for various launch equipment, small multi-purpose vehicles and other platforms. The focus of antenna miniaturization is the trade-off between performance and size. Therefore, under this urgent demand for high performance and high reliability, as well as light weight and high integration, a series of advanced electronic interconnection methods and high-level process technologies have emerged.

[0003] Traditional ultra-wideband antenna units such as log-periodic antennas, planar or conical spiral antennas, biconical antennas, etc. are not suitable for use in ultra-wideband arrays due to their large size. Vivaldi antennas are a type of tapered slot antennas and are ultra-wideband antennas. This type of antenna has the advantages of wide bandwidth, symmetrical radiation pattern, stable gain, simple structure, low profile, and easy integration. It has been widely used in radar systems, indoor and outdoor communication systems, measurement equipment and other fields. The antenna array involved in the present invention is a metallized tapered slot Vivaldi oblique polarization antenna unit, which has azimuth and elevation dual polarization capabilities; and because the antenna frequency band covers 6-18GHz, the antenna unit spacing is only 9mm. In order to meet the functional requirements of high frequency bands and small spacing, SMP connectors or smaller SSMP connectors are generally used to transmit radio frequency signals during antenna design. When the frequency band is low or the antenna is designed to be single-polarized, the distance between adjacent connectors is large, which meets the machining requirements, and a screw-mounted connector can be used to install it in the structure. However, when the frequency band is increased and the antenna is designed to be dual-polarized, the installation space for the connector will be greatly constrained. For example, in the antenna array involved in the embodiment of the present invention, the dual-polarized antenna has a minimum center distance of less than 6 mm (margin less than 3 mm) between adjacent connectors. Due to the design structure size and machining accuracy of the antenna array, a screw-mounted connector cannot be used, which increases the difficulty of assembly.

[0004] Existing micro-miniature (SMP / SSMP) RF connectors are mainly fixed and grounded by flange installation, threaded installation, conductive adhesive bonding and welding. Due to structural spacing limitations, the first two installation methods are not applicable to the embodiments of the present invention; when conductive adhesive bonding is used, the conductivity of the conductive adhesive and the structural strength after curing are low, so it cannot meet the requirements of multiple plugging and unplugging of subsequent cables or modules, and is also not applicable to the embodiments of the present invention; therefore, the micro-miniature (SMP / SSMP) RF connector involved in the present invention is fixed and grounded by welding. During welding installation, the existing process generally uses hot plate welding, induction welding, low-temperature vacuum brazing or vacuum vapor phase welding in conjunction with corresponding tooling, which has certain defects:

[0005] 1. When using hot plate welding, the size of the product is greatly restricted due to the size of the hot plate and the uniformity of heating. When the product size is large, it cannot be applied; and generally there is a certain temperature difference between the middle and the surrounding of the hot plate, which can easily lead to uneven solder spreading around the solder joints, affecting the grounding effect of the connector.

[0006] 2. When using induction welding, due to its heating principle and the material properties of the welding object, the temperature surge during welding of aluminum alloy shells is generally large, which can easily cause temperature overshoot and damage the shell; when the connectors are relatively dense (the distance is less than or equal to 2 times the diameter of its heating coil), the solder of other connectors around it is easy to melt repeatedly during the heating process, causing solder loss or performance degradation, and excessively high temperatures can easily cause excessive solder overflow at the gap, resulting in defects such as internal short circuits in the connector.

[0007] 3. When using low-temperature vacuum brazing or vacuum vapor phase welding, high requirements are placed on the antenna array opening size accuracy, positioning method, etc. However, due to limitations such as the antenna array weight reduction design and processing technology, the structural strength is often reduced, and deformation is prone to occur during assembly or welding, affecting the next step of assembly.

[0008] 4. When using ordinary pressing plates or pressing blocks as tooling, the tooling only provides downward pressure, and its ability to maintain the shape of the antenna array is minimal. At the same time, the downward pressure applied by ordinary tooling during welding is difficult to be evenly distributed on each micro-miniature (SMP / SSMP) RF connector, resulting in protrusions, skewness, poor solder penetration or excessive tin overflow, short circuits and other defects in the connector after welding. The qualified rate after welding is only 40-55%, which seriously affects the performance of the product antenna feeder.

[0009] The traditional integration method can meet the design requirements of antenna array RF connector installation under low frequency band and low density, but it is not applicable to the dual-polarization high-density antenna array with light weight, high density and connector center spacing of less than 6mm in the present invention. Therefore, it is urgent to establish a method for installing micro-miniature (SMP / SSMP) RF connectors on high-density antenna arrays to solve the series of problems such as array deformation and poor welding in the process of installing micro-miniature (SMP / SSMP) RF connectors on existing antenna arrays, further improve the performance of antenna feed, and at the same time, the process is simple and fast, the telecommunications indicators are excellent, and the reliability is high.

[0010] In view of the above-mentioned defects, the inventors of the present invention finally obtained the present invention after a long period of research and practice. Summary of the invention

[0011] The purpose of the present invention is to solve the problems of array deformation and poor welding that occur during the process of attaching micro-miniature (SMP / SSMP) radio frequency connectors to the existing antenna array surface, and to provide a method for attaching micro-miniature radio frequency connectors to a high-density antenna array surface.

[0012] In order to achieve the above object, the present invention discloses a method for assembling a micro-sized radio frequency connector on a high-density antenna array, comprising the following steps:

[0013] S1, manufacturing a lightweight antenna reflector with evenly distributed step through holes and pre-plated solderable coating inside the holes;

[0014] S2, manufacturing a metallized gradient slot Vivaldi oblique polarization antenna unit with blind holes and pre-plated solderable coating in the holes;

[0015] S3, manufacture welding tooling with elastic devices and shape-preserving functions;

[0016] S4, design a special solder ring with pre-flux coating;

[0017] S5, first fill the blind hole of the antenna unit with solder, install it at the corresponding position on the antenna reflector and combine it with the bottom plate of the welding tooling, after installation, the antenna unit faces downward and the antenna reflector faces upward, then put the special solder ring pre-coated with flux into the step through hole of the antenna reflector so that it is just flat in the hole, and then install the micro-sized RF connector, the positioning device of the welding tooling and the part providing downward pressure in sequence;

[0018] S6 uses low-temperature brazing equipment to determine the appropriate temperature curve and then set the corresponding program. After placing the assembled products and tooling into the equipment, the program is started to complete the assembly process of the micro-RF connector, and high-quality interconnection between the connector and the antenna array and the antenna reflector is achieved through one-time welding.

[0019] In step S1, the processing steps of the reflector are heat treatment, shape processing, drilling and milling of step holes, burr removal, cleaning, overall surface conductive oxidation, and local solderability coating. The aperture accuracy of the step holes of the reflector is required to be ±0.01-0.02mm, and the flatness of the reflector is required to be 0.05±0.01mm.

[0020] In step S2, the antenna array material is made of aluminum alloy 5A06 and 3A21. The antenna array is processed by high-speed milling method, and the dimensional accuracy is ±0.02-0.03mm. The aperture accuracy of the blind hole of the antenna array is required to be ±0.01-0.02mm. The antenna array is provided with positioning pins and is fixed to the antenna reflector plate by screws. It has its own positioning pins to achieve installation positioning, and the verticality of the positioning pins and its base is within 0.02mm.

[0021] In the step S1 and step S2, the main material of the solderable plating layer in the welding area is silver or gold, the thickness of silver is 0.07 μm, and the middle layer material includes copper or nickel, and the thickness of the middle layer is 0.03 μm.

[0022] In step S3, the welding tool is of split assembly design, including a base plate, a spring pin assembly fixing plate, a guide limit bolt, a guide limit pin, a spring pin assembly and a customized non-metallic ejector pin. The welding tool applies radial pressure to the connector through an elastic device, directly contacts the connector through the non-metallic ejector pin, controls the direction and size of the pressure through the guide limit pin, and controls the downward pressure within a range of 0N to 3N.

[0023] The downward pressure of the pin assembly is 2N. The non-metallic ejector pin material is any one of polytetrafluoroethylene plate, polytetrafluoroethylene rod, epoxy glass cloth plate, epoxy glass cloth rod, synthetic stone, ceramic, and glass. The welding tooling material is 5A06, 3A21 series aluminum or synthetic stone.

[0024] In step S4, the material of the solder ring is Sn63Pb37, Sn70Pb18In12 or Sn62Pb36Ag2, the thickness is customized according to the volume of the welding area, and the solder ring is pre-coated with flux.

[0025] In step S4, the material of the solder ring is Sn70Pb18In12, the pre-coated flux is ROL0 no-clean type, the pre-coated flux content is 0.5wt.%-3.5wt.%, and the volume V of the material ring is calculated according to the theoretical formula: solder amount = α×V theoretical amount, where 0.6<α<1

[0026] In step S5, the outer conductor of the micro-sized RF connector is fixed by welding to the stepped through hole on the antenna reflector through a solder ring, and the inner conductor of the micro-sized RF connector is fixed by welding to the blind hole on the antenna array through Sn70Pb18In12 solder paste. Before welding, the antenna array surface is first installed on the bottom plate and fixed with the guide limit pin; then the solder ring and the corresponding connector are installed; then the spring pin assembly and the spring pin assembly fixing plate are combined together and fixed to the antenna array surface with the guide limit bolt.

[0027] In the step S5, low-temperature vacuum brazing or vacuum vapor phase welding is used once to complete the assembly of the inner / outer conductors of the micro-sized RF connector.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] 1. The present invention uses a one-time low-temperature vacuum brazing or vacuum vapor phase welding method to complete the simultaneous assembly of the inner and outer conductors of the micro-RF connector. While saving energy and improving efficiency, it avoids the fatigue effect and thermal stress deformation of solder and metal materials caused by multiple heating. The actual measured appearance and indicators after welding are good, the defective rate of connector protrusions exceeding the surface is reduced by 95%, and the defective rate of outer conductor connection is reduced by 99%. It is suitable for use in the X-Ku band, meets the environmental test requirements of 500 temperature cycles (-50℃~+65℃) and 6.06g random vibration, and has good reliability and environmental adaptability;

[0030] 2. The present invention can realize the assembly of micro-miniature (SMP / SSMP) RF connectors on antenna reflectors with a center distance of ≤6mm between adjacent connectors. Compared with the traditional assembly method, it basically solves the problems of connector protrusion, skewness, poor solder penetration or excessive tin overflow after welding, and has better plane consistency. The defective rate of connector protrusion and skewness is reduced by 95%, and the rate of poor connection or short circuit of the outer conductor is reduced by 99%. It meets the higher technical requirements of products for miniaturization and high consistency;

[0031] 3. The process method of the present invention has higher production efficiency. The outer / inner conductor of the micro-miniature (SMP / SSMP) RF connector is connected to the antenna reflector / antenna array by one welding, which reduces repeated steps and reduces the impact of multiple heating on the flatness of the antenna reflector, ensuring assembly accuracy and reliability, and greatly improving production efficiency. Compared with the production time of traditional micro-miniature (SMP / SSMP) RF connector assembly, it is shortened by 30%. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a structural schematic diagram of Example 1;

[0033] Figure 2 It is the process flow chart of Example 1;

[0034] Figure 3 It is a structural schematic diagram of Example 2;

[0035] Figure 4 It is the process flow chart of Example 2;

[0036] Figure 5 The welding temperature curves of Example 1 and Example 2 are shown;

[0037] Figure 6 It is a structural schematic diagram of a comparative example;

[0038] Figure 7 This is the welding temperature curve of the comparative example.

[0039] The numbers in the figure represent:

[0040] 1-pressing plate tooling; 2-weldable step through hole of antenna array; 3-antenna reflector; 4-weldable blind hole; 5-antenna element; 6-inner conductor of RF connector; 7-outer conductor of RF connector; 8-micro-miniature (SMP / SSMP) RF connector; 9-Sn63Pb37 solder wire; 10-limiting tooling; 11-spring; 12-Sn70Pb18In12 solder ring; 13-guide limiting bolt; 14-spring pin assembly fixing plate; 15-guide limiting pin; 16-Sn70Pb18In12 solder paste; 17-base plate; 18-spring pin assembly. DETAILED DESCRIPTION

[0041] The above and other technical features and advantages of the present invention are described in more detail below in conjunction with the accompanying drawings.

[0042] Example 1

[0043] The structure of Example 1 is as follows Figure 1 As shown, compared with the comparative example, the main differences are:

[0044] (1) A limit fixture 10 and a spring 11 are placed under the pressing block of Example 1, wherein the spring contacts the inside of the micro-miniature (SMP / SSMP) RF connector to provide downward pressure during welding;

[0045] (2) In Example 1, the solder wire is replaced with a customized Sn70Pb18In12 solder ring 12, and the steps of applying the solder wire are reduced.

[0046] The assembly process of Example 1 is as follows Figure 2As shown, a Sn70Pb18In12 solder ring 12, a micro-miniature (SMP / SSMP) RF connector 8, a limit fixture 10, a spring 11, and a pressure plate fixture 1 are placed in sequence on the antenna reflector 3, and the outer conductor 7 of the micro-miniature (SMP / SSMP) RF connector and the antenna reflector 3 are interconnected by low-temperature vacuum brazing or vacuum vapor phase welding process; the antenna array 5 is installed to the other side of the antenna reflector 3 by screws, and the inner conductor 6 of the micro-miniature (SMP / SSMP) RF connector and the antenna array 5 are hard-connected by interference fit through a solderable blind hole 4.

[0047] Example 2

[0048] The structure of Example 2 is as follows Figure 3 As shown in the process flow chart Figure 4 As shown, compared with the comparative example, the main differences are:

[0049] (1) In Example 2, a welding tool is designed, including: a base plate 17, a spring pin assembly fixing plate 14, a guide limit bolt 13, a guide limit pin 15, and a spring pin assembly 18; the welding tool can accurately apply downward pressure to the micro-miniature (SMP / SSMP) RF connector during welding, thereby reducing connector protrusions after welding, tin overflow inside the connector, poor contact of the outer conductor, and short circuit of the outer conductor.

[0050] (2) In Example 2, the blind hole of the antenna element and the inner conductor of the micro-miniature (SMP / SSMP) RF connector are connected by welding using Sn70Pb18In12 solder paste 16 instead of hard connection by interference fit.

[0051] The assembly process of Example 2 is as follows Figure 3 As shown, first, the spring pin assembly 18 is integrated into the spring pin assembly fixing plate 14; the antenna reflector 3 is integrated onto the bottom plate 17 with the guide limit pin 15; an appropriate amount of Sn70Pb18In12 solder paste 16 is added into the antenna element blind hole 4, and the antenna element is fixed to the corresponding position of the antenna reflector with screws, and Sn70Pb18In12 solder ring 12 and micro-miniature (SMP / SSMP) RF connector 8 are placed on the antenna reflector in sequence, and then the integrated spring pin assembly is installed and fixed together with the guide limit bolt 13. After the assembly is completed, a low-temperature vacuum brazing or vacuum vapor phase welding process is used to simultaneously complete the interconnection between the inner and outer conductors of the micro-miniature (SMP / SSMP) RF connector and the antenna reflector, as well as the interconnection between the antenna element.

[0052] Comparative Example

[0053] The comparative structure is as follows Figure 6As shown, it includes an antenna reflector 3, a micro-miniature (SMP / SSMP) RF connector 8, an antenna array solderable step through hole 2, an antenna array 5, an antenna array solderable blind hole 4, a pressing plate fixture 1 and a Sn63Pb37 solder wire 9. For a clearer illustration effect, the number of connectors is reduced.

[0054] The assembly process of the comparative example is as follows Figure 6 As shown. First, the antenna reflector 2 is prepared by mechanical processing, and the antenna array surface solderable step through hole 2 and the antenna element solderable blind hole 4 are partially silver-plated; during assembly, a small amount of flux is applied to the welding surface, and then Sn63Pb37 solder wire 9, micro-miniature (SMP / SSMP) RF connector 8, and pressing plate tooling 1 are placed in sequence; during welding, the micro-miniature (SMP / SSMP) RF connector outer conductor 7 and the antenna reflector 3 are interconnected by low-temperature vacuum brazing or vacuum vapor phase welding process; the antenna element 5 is installed to the other side of the antenna reflector 3 by screws, and the micro-miniature (SMP / SSMP) RF connector inner conductor 6 and the antenna element 5 are hard-connected by interference fit through the solderable blind hole 4.

[0055] like Figure 5 and Figure 7 As shown, compared with the comparative example, the post-welding effect of Example 1 is that the defective rate of connector protrusion exceeding the surface is reduced by 64%, and the defective rate of outer conductor connection is reduced by 87%, but some connectors still have tin overflow after soldering, which needs manual repair. The prepared product meets the environmental test requirements of 500 temperature cycles (-50℃~+65℃) and 6.06g random vibration, and has good reliability and environmental adaptability.

[0056] Compared with the comparative example, the post-welding effect of Example 2 is that the defective rate of connector protrusion exceeding the surface is reduced by 95%, and the defective rate of outer conductor connection is reduced by 99%. It is suitable for use in the X-Ku band, meets the environmental test requirements of 500 temperature cycles (-50℃~+65℃) and 6.06g random vibration, and has good reliability and environmental adaptability.

[0057] The above description is only a preferred embodiment of the present invention, which is only illustrative and not restrictive of the present invention. Those skilled in the art understand that many changes, modifications, and even equivalences may be made to the present invention within the spirit and scope defined by the claims of the present invention, but all of them will fall within the scope of protection of the present invention.

Claims

1. A method for attaching a miniature radio frequency connector to a high-density antenna array, characterized in that: The following steps are involved: S1, manufacturing a lightweight antenna reflector with evenly distributed step through holes and pre-plated solderable coating inside the holes; S2, manufacturing a metallized gradient slot Vivaldi oblique polarization antenna unit with blind holes and pre-plated solderable coating in the holes; S3, manufacture welding tooling with elastic devices and shape-preserving functions; S4, design a special solder ring with pre-flux coating; S5, first fill the blind hole of the antenna unit with solder, install it at the corresponding position on the antenna reflector and combine it with the bottom plate of the welding tooling, after installation, the antenna unit faces downward and the antenna reflector faces upward, then put the special solder ring pre-coated with flux into the step through hole of the antenna reflector so that it is just flat in the hole, and then install the micro-sized RF connector, the positioning device of the welding tooling and the part providing downward pressure in sequence; S6 uses low-temperature brazing equipment to determine the appropriate temperature curve and then set the corresponding program. After placing the assembled products and tooling into the equipment, the program is started to complete the assembly process of the micro-RF connector, and high-quality interconnection between the connector and the antenna array and the antenna reflector is achieved through one-time welding.

2. A method for attaching a micro-sized RF connector to a high-density antenna array as claimed in claim 1, characterized in that: In step S1, the processing steps of the antenna reflector are heat treatment, shape processing, drilling and milling step holes, burr removal, cleaning, overall surface conductive oxidation, and local solderability coating. The aperture accuracy of the step holes of the reflector is required to be ±0.01-0.02mm, and the flatness of the reflector is required to be 0.05±0.01mm.

3. The method for attaching a micro-sized RF connector to a high-density antenna array as claimed in claim 1, characterized in that: In step S2, the antenna array material in the oblique polarization antenna unit is selected from aluminum alloy 5A06 and 3A21. The antenna array is processed by high-speed milling method, and the dimensional accuracy is ±0.02-0.03mm. The aperture accuracy of the blind hole of the antenna array is required to be ±0.01-0.02mm. The antenna array is provided with a positioning pin and is fixed to the antenna reflector plate by screws. It has its own positioning pin to achieve installation positioning, and the verticality of the positioning pin and its base is within 0.02mm.

4. The method for assembling a micro-sized RF connector on a high-density antenna array as claimed in claim 1, characterized in that: In the step S1 and step S2, the main material of the solderable plating layer in the welding area is silver or gold, the middle layer material includes copper or nickel, the silver thickness is 0.07 μm, and the middle layer thickness is 0.03 μm.

5. The method for assembling a micro-sized RF connector on a high-density antenna array as claimed in claim 1, characterized in that: In step S3, the welding tool is of split assembly design, including a base plate, a spring pin assembly fixing plate, a guide limit bolt, a guide limit pin, a spring pin assembly and a customized non-metallic ejector pin. The welding tool applies radial pressure to the connector through an elastic device, directly contacts the connector through the non-metallic ejector pin, controls the direction and size of the pressure through the guide limit pin, and controls the downward pressure within a range of 0N to 3N.

6. A method for attaching a micro-sized radio frequency connector to a high-density antenna array as claimed in claim 5, characterized in that: The downward pressure of the pin assembly is 2N. The non-metallic ejector pin material is any one of polytetrafluoroethylene plate, polytetrafluoroethylene rod, epoxy glass cloth plate, epoxy glass cloth rod, synthetic stone, ceramic, and glass. The welding tooling material is 5A06, 3A21 series aluminum or synthetic stone.

7. A method for assembling a micro-sized RF connector on a high-density antenna array as claimed in claim 1, characterized in that: In step S4, the material of the solder ring is Sn63Pb37, Sn70Pb18In12 or Sn62Pb36Ag2, the thickness is customized according to the volume of the welding area, and the solder ring is pre-coated with flux.

8. The method for assembling a micro-sized radio frequency connector on a high-density antenna array as claimed in claim 1, characterized in that: In step S4, the solder ring material is Sn70Pb18In12, the pre-coating flux is ROL0 no-clean type, the pre-coating flux content is 0.5wt.%-3.5wt.%, and the volume V of the material ring is calculated according to the theoretical formula: solder amount = α×V theoretical amount, wherein 0.6<α<1.

9. The method for assembling a micro-sized radio frequency connector on a high-density antenna array as claimed in claim 1, characterized in that: In step S5, the outer conductor of the micro-sized RF connector is fixed by welding to the stepped through hole on the antenna reflector through a solder ring, and the inner conductor of the micro-sized RF connector is fixed by welding to the blind hole on the antenna array through Sn70Pb18In12 solder paste. Before welding, the antenna array surface is first installed on the bottom plate and fixed with the guide limit pin; then the solder ring and the corresponding connector are installed; then the spring pin assembly and the spring pin assembly fixing plate are combined together and fixed to the antenna array surface with the guide limit bolt.

10. The method for assembling a micro-sized radio frequency connector on a high-density antenna array as claimed in claim 1, characterized in that: In the step S5, low-temperature vacuum brazing or vacuum vapor phase welding is used once to complete the assembly of the inner / outer conductors of the micro-sized RF connector.

Images