High-density metal package radio frequency assembly and method of assembly

Abstract

The application provides a high-density metal package radio frequency assembly and an assembling method thereof, characterized by comprising: a metal tube shell, the upper surface of the metal tube shell is provided with an up-down penetrating mounting area; a PCB mounting step is arranged in the mounting area and used for arranging a PCB; a cover plate mounting sink is arranged on the upper and lower surfaces of the metal tube shell along the edge of the mounting area and used for arranging a metal cover plate; a radio frequency connector mounting through hole is arranged on the side surface of the metal tube shell, a solder ring arranging hole is arranged on the edge of the axial end of the radio frequency connector mounting through hole; a radio frequency connector is fixedly mounted in the radio frequency connector mounting through hole; the upper and lower surfaces of the metal tube shell are respectively provided with a chamfer adjacent to the corresponding metal cover plate; the edge of the metal cover plate is provided with a chamfer; the chamfers on the upper and lower surfaces of the metal tube shell are respectively assembled with the chamfers on the edges of the corresponding metal cover plates to form a V-shaped sink structure; the application adopts a reflow soldering mode for mounting and connecting, and the package structure has air tightness, and the reliability of the radio frequency assembly can be significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of radio frequency filtering components, and in particular relates to a high-density metal-packaged radio frequency component and its assembly method. Background Technology

[0002] Radio frequency (RF) components refer to miniaturized microwave circuit products composed of RF elements and other parts, connected to external circuits via coaxial, waveguide, or other transmission lines, capable of independently performing specific functions within a system. With the development of communication technology, the requirements for miniaturization and integration of products are becoming increasingly stringent. The manufacturing process of RF components often involves numerous steps such as component mounting, circuit board mounting, RF connector installation, and cover plate encapsulation. In some special application scenarios, RF components are also required to have excellent sealing properties, which further increases the difficulty of product packaging structure and assembly process design.

[0003] Conventional printed circuit boards are mostly mounted on one side and then secured in metal or ceramic housings by screws or conductive adhesive. Double-sided mounting and soldering can effectively increase the board mounting density of components, but it presents the process challenge of using multi-temperature gradient soldering. The reflow temperature of the first side often exceeds the temperature limit of the components, which has an adverse effect on the reliability of the product. Therefore, it is not widely used in actual production.

[0004] For RF connectors used in RF components, silver paste bonding is often used for assembly. Silver paste bonding requires manual application of silver paste to cover the RF connector shell. After being inserted into the shell mounting hole, it is baked at high temperature to cure. The coating process is prone to causing contamination of the shell, and the bonding strength of silver paste is not high. During use, problems such as silver paste embrittlement and RF connector detachment may occur, which are inconvenient in production and use.

[0005] After the RF component printed circuit board is mounted and installed into a housing, it is often sealed with a screw-type cover plate. This requires the housing to have screw mounting holes, and the cover plate to have a certain thickness. The sealed product is not hermetically tight. Although parallel soldering can achieve product sealing, it has strict limitations on the size of the product housing and cannot be used for packaging slightly larger products, so its practical application is relatively limited.

[0006] For the reasons mentioned above, conventional RF component manufacturing processes mostly employ single-sided mounting technology, which suffers from low component mounting density, lack of airtightness, complex production processes, and low actual yield, thus hindering the widespread application of the products. Summary of the Invention

[0007] To address the problems existing in the background technology, this invention provides a high-density metal-packaged RF component and its assembly method. The frame-type metal housing design enables the installation of double-sided printed circuit boards and RF connectors, as well as the hermetic sealing of the metal cover. The same solder is used for double-sided mounting of the circuit board (process optimization), and low-temperature solder reflow soldering is employed to achieve the installation of the circuit board, RF connector, and housing, and the hermetic sealing of the cover. The production process is simple, the product yield is high, and miniaturized, hermetic-packaged, and highly reliable RF components are produced, suitable for mass production.

[0008] To achieve the above-mentioned technical objectives, one aspect of the present invention provides a high-density metal-packaged radio frequency (RF) component, comprising: a metal housing, a PCB board, and an RF connector. The PCB board has components mounted on both sides. A through-mount area is provided on the top of the metal housing. A PCB mounting step and RF signal shielding beams are provided within the mounting area. The PCB board is mounted on the PCB mounting step. Cover plate mounting recesses are provided on the upper and lower surfaces of the metal housing along the edges of the mounting area, and metal cover plates are mounted on the cover plate mounting recesses. An RF connector mounting through-hole is provided on the side of the metal housing. A solder ring mounting groove is provided at the edge of the axial end of the RF connector mounting through-hole. The RF connector is fixedly mounted within the RF connector mounting through-hole. A 45° chamfer is provided on the upper and lower surfaces of the metal housing adjacent to the corresponding metal cover plate. A 45° chamfer is provided at the edge of the metal cover plate. The chamfers on the upper and lower surfaces of the metal housing, when assembled with the chamfers at the edges of the corresponding metal cover plates, form a V-shaped recessed structure.

[0009] Another aspect of the present invention provides an assembly method for a high-density metal-packaged radio frequency (RF) component, the assembly method being applied to the aforementioned high-density metal-packaged RF component, comprising:

[0010] S1: PCB board mounting. Select the side of the board with lighter components or fewer components as the first side. Reflow solder the components on the first side of the PCB board using 63Sn37Pb solder. Then reflow solder the components on the second side of the PCB board using the same 63Sn37Pb solder.

[0011] S2: Apply low-melting-point solder paste to the solder paste receiving tank of the PCB mounting step and RF signal shielding beam in the metal tube; and use tweezers to insert the PCB board into the metal tube and press it lightly to make it fully fit with the PCB mounting step.

[0012] S3: Insert the RF connector into the RF connector mounting through hole, install the solder ring in the solder ring placement hole, and apply adhesive to cover the solder ring, RF connector, and metal housing.

[0013] S4: Install metal cover plates on the cover plate mounting platforms on both the upper and lower sides of the metal tube shell, and place a solder ring in the V-shaped groove structure formed after assembly. After placement, use a clamp to hold and fix it.

[0014] S5: Place the assembled product from step S4 into a reflow oven for reflow soldering. After soldering, remove the fixture to obtain the assembled RF component.

[0015] The present invention has at least the following beneficial effects

[0016] This invention reduces the weight of RF components through a frame-type metal housing design; the internal PCB mounting steps and RF signal shielding beams ensure the installation of double-sided PCB boards; the RF connector is installed on the side wall of the metal housing, and its internal leads overlap the pads on the upper and lower surfaces of the printed circuit board to ensure the output of RF signals; the cover plate is sealed by reflow soldering, realizing the miniaturization, high density, and high reliability of RF components.

[0017] During assembly and manufacturing, this invention utilizes an adhesive process to achieve double-sided mounting of PCB boards using the same 63Sn37Pb solder, thus avoiding the risk of component damage caused by excessively high reflow temperatures when using dissimilar solders.

[0018] By applying low-melting-point solder, adhesive, and reflow tooling to the housing steps, the assembly and packaging of the PCB board, RF connector, and double-sided cover plate are achieved, greatly simplifying the component manufacturing process, achieving a high yield, and meeting the needs of mass production. At the same time, by placing solder rings in the V-shaped recessed structure formed after assembly, the metal cover plate and metal shell are welded through the solder rings in the V-shaped recessed structure, and the RF connector and metal shell are welded through the solder ring placement holes, thus ensuring the hermetic packaging of the RF component.

[0019] In summary, the above-mentioned solutions simplify the production process, increase the product yield, and produce miniaturized, hermetically sealed, and highly reliable radio frequency components suitable for mass production. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the assembly structure of the present invention;

[0021] Figure 2 This is a schematic diagram of the structure of the metal tube shell of the present invention;

[0022] Figure 3 This is a schematic diagram of the assembly structure of the radio frequency connector of the present invention. Detailed Implementation

[0023] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0024] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0025] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present 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, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0026] Please see Figures 1-3 One aspect of the present invention provides a high-density metal-packaged radio frequency (RF) component, comprising: a metal housing, a PCB board, and an RF connector. The PCB board has components mounted on both sides. A through-mount area is provided on the top of the metal housing. A PCB mounting step and RF signal shielding beams are provided within the mounting area. The PCB board is mounted on the PCB mounting step. Cover plate mounting recesses are provided on the upper and lower surfaces of the metal housing along the edges of the mounting area, and metal cover plates are mounted on the cover plate mounting recesses. An RF connector mounting through-hole is provided on the side of the metal housing. A solder ring mounting groove is provided at the edge of the axial end of the RF connector mounting through-hole. The RF connector is fixedly mounted within the RF connector mounting through-hole. A 45° chamfer is provided on the upper and lower surfaces of the metal housing adjacent to the corresponding metal cover plate. A 45° chamfer is provided at the edge of the metal cover plate. The chamfers on the upper and lower surfaces of the metal housing, when assembled with the chamfers at the edges of the corresponding metal cover plates, form a V-shaped recessed structure.

[0027] Preferably, the RF connector mounting hole has a positioning plug at its axial bottom to prevent the RF connector from being inserted too deeply. During installation, the RF connector is positioned by the positioning plug at the axial bottom of the mounting hole and by applying adhesive to the external end.

[0028] Preferably, the RF signal shielding beam and PCB mounting steps are provided with solder paste receiving grooves, and the components, PCB board, metal shell, cover plate and RF connector are all installed and connected by reflow soldering to achieve the airtightness of the packaging structure.

[0029] In this embodiment, a frame-type metal housing is provided with a PCB board mounting step on top; the side of the metal housing has an RF connector mounting through hole; and the upper and lower surfaces of the metal housing have cover plate mounting recesses along the edges of the mounting area for cover plate mounting. The edges of the housing and cover plate have chamfered recesses, forming a V-shaped recess structure after assembly to accommodate the solder paste applied to the cover plate. It is recommended that the V-shaped recess structure be 2-4 mm wide and have a depth equal to the cover plate thickness; the metal housing should be made of materials such as Kovar, stainless steel, or aluminum, with a nickel or gold plating to maintain good solderability. It has a PCB board mounting step and an RF connector mounting through hole. The PCB board mounting step is 1-3 mm wide for applying solder paste and mounting the PCB board. A shallow solder-receiving groove should be provided on the PCB board mounting step, with a groove width of 1 / 2 the width of the PCB board mounting step and a depth of 0.5-1 mm to accommodate the applied solder paste.

[0030] The depth of the mounting through-hole for the RF connector is the same as the length of the RF connector housing, and the hole diameter is generally 0.05–0.15 mm larger than the RF connector housing. The mounting through-hole for the RF connector has the same shape as the RF connector and should maintain a good fit. A positioning plug is provided at the bottom of its axial end to prevent the RF connector from being inserted too deeply, and a solder ring mounting groove is provided at its end.

[0031] The solder ring at the RF connector tip has a width of 0.3–0.5 mm and a thickness of 0.2–0.3 mm, with flux pre-applied to its surface. The solder ring mounting hole size is the same as the corresponding solder ring, with positive tolerance.

[0032] Grounding pads are provided around the contact surface between the PCB board and the metal casing for reflow soldering with the PCB board mounting steps. The width of the grounding pads should be 1mm wider than the width of the PCB board mounting steps to accommodate the overflow of solder after melting, forming a weld with the sidewall of the metal casing, improving the PCB board mounting strength, and avoiding the generation of solder dross and solder balls.

[0033] The metal casing has an extended radio frequency signal shielding rib structure inside, and a grounding pad is provided on the corresponding PCB board. During PCB board installation, solder paste is applied and reflow soldered simultaneously to improve the grounding and signal shielding functions of the radio frequency component, while also enhancing the structural strength of the radio frequency component.

[0034] The metal cover mounting clamp is a spring clamping structure, such as a long tail clamp. It is easy to use and has strong applicability to products of different sizes. It can apply pressure to the four corners of the upper and lower covers respectively, ensuring the flatness of the upper and lower covers and the housing during installation, and improving the pass rate of the sealing airtightness.

[0035] Another aspect of the present invention provides an assembly method for a high-density metal-packaged radio frequency (RF) component, the assembly method being applied to the aforementioned high-density metal-packaged RF component, comprising:

[0036] S1: PCB board mounting. Select the side of the board with lighter components or fewer components as the first side. Reflow solder the components on the first side of the PCB board using 63Sn37Pb solder. Then reflow solder the components on the second side of the PCB board using the same 63Sn37Pb solder.

[0037] Preferably, before reflow soldering the components on the second side of the PCB, the junction between the heavy components weighing more than 2g on the first side of the PCB and the printed circuit board is reinforced with patch red glue or dotted epoxy glue.

[0038] Preferably, the peak temperature of the reflow curve during PCB board mounting is 40-60°C higher than the melting point of the solder paste, and the holding time is 40-70 seconds; the heating rate at any time does not exceed 4°C / s, and the cooling rate during the cooling phase does not exceed 5°C / s.

[0039] In this embodiment, both sides of the PCB board are reflow soldered using 63Sn37Pb solder. Before reflowing the second side, conventional components can be held in place by the solder adhesion. For heavy components (>2g) on ​​the first side, surface-mount adhesive or epoxy glue is applied for reinforcement to prevent component detachment during reflow. The adhesive does not require pre-baking and curing; it cures automatically during the reflow process described in this article.

[0040] The peak temperature of the reflow curve is 40-60°C higher than the melting point of the solder paste, and the holding time is 40-70 seconds; the heating rate should not exceed 4°C / s at any time, and the cooling rate should not exceed 5°C / s during the cooling phase.

[0041] An eight-zone hot air reflux furnace is recommended for reflux. Reflux temperature zone settings: 150℃, 120℃, 155℃, 160℃, 170℃, 180℃, 206℃, 235℃; transfer rate: 62cm / min.

[0042] S2: Apply low-melting-point solder paste to the solder paste receiving tank of the PCB mounting step and RF signal shielding beam in the metal tube; and use tweezers to insert the PCB board into the metal tube and press it lightly to make it fully fit with the PCB mounting step.

[0043] Preferably, the low-melting-point solder paste comprises: SnAg, InSn, or SnBi.

[0044] S3: Insert the RF connector into the RF connector mounting through hole, install the solder ring (SnAg, InSn, SnBi, etc.) in the solder ring placement hole, and apply adhesive to cover the solder ring, RF connector and metal shell.

[0045] Preferably, after step S2, the connection points between the RF connector and the PCB board pads are soldered using SAC305 solder at a soldering iron temperature of 350°C. An adhesive, such as surface mount red glue, is applied to cover the solder ring, RF connector, and metal housing to prevent the RF connector and solder ring from shifting or falling off during reflow.

[0046] In this embodiment, due to the small size of the RF connector, a pre-placed solder ring is used. The PCB board and cover plate are reflow soldered by applying solder paste in a solder bath. After the PCB board is placed, SAC305 solder should be used to solder the connection points between the PCB board and the RF connector's internal pins to prevent displacement of the RF pins and the printed circuit board during reflow.

[0047] S4: Install metal cover plates on the cover plate mounting platforms on both the upper and lower sides of the metal tube shell, and place a solder ring in the V-shaped groove structure formed after assembly. After placement, use a clamp to hold and fix it.

[0048] S5: Place the assembled product from step S4 into a reflow oven for reflow soldering. After soldering, remove the fixture to obtain the assembled RF component.

[0049] Preferably, the peak temperature in the reflow soldering of step S5 does not exceed 185°C, and the reflow chain speed is less than the reflow chain speed during PCB board mounting.

[0050] Preferably, when the adhesive in step S3 is red glue, after the reflow soldering in step S5 is completed, the RF component is placed on a 120°C heating table to fully preheat the metal housing, and then the softened red glue in step S3 is scraped off with a blade.

[0051] In this embodiment, the fixture is designed to achieve RF connector installation and hermetic sealing of the double-sided cover plate in a single reflow soldering operation. The RF connector is secured using red glue, which involves applying adhesive to the solder ring, RF connector, and metal housing to prevent pin or solder pad misalignment during reflow soldering.

[0052] In this embodiment, the reflow profile settings in step S5 should ensure that the low-melting-point solder is fully melted while avoiding remelting of the solder joints of double-sided mounted components on the PCB. Furthermore, due to the large heat capacity of the PCB and metal casing, the reflow chain speed should be appropriately reduced to ensure good solder melting while maintaining a peak temperature not exceeding 185°C during reflow soldering. An eight-zone hot air reflow oven is recommended. Reflow temperature zone settings: 95°C, 115°C, 130°C, 145°C, 155°C, 175°C, 180°C, 185°C; Transfer rate: 45cm / min.

[0053] This embodiment also includes: visual inspection of the weld seams and airtightness testing of the manufactured RF components. The solder should melt well and be bright and wetted; the weld seams at the junction of the RF connector and cover plate with the metal shell should be continuous and without defects; and the packaged product is immersed in fluorinated oil for leak detection, and any leaks due to poor packaging are marked.

[0054] Use a soldering iron or hot air blower to heat and melt the solder wire to repair the marked leak points in the package structure. After repair, inspect again.

[0055] After assembly, weld appearance inspection and component airtightness testing procedures are set up to repair any leaks in the packaging, ensuring the product's airtightness.

[0056] In summary, this invention reduces the weight of the RF component through a frame-type metal housing design; the internal PCB mounting steps ensure the installation of double-sided PCB boards; the RF connector is installed on the side wall of the metal housing, and its internal leads overlap the pads on the upper and lower surfaces of the printed circuit board, ensuring the output of RF signals; the cover plate is sealed by reflow soldering, realizing the miniaturization, high density, and high reliability of the RF component.

[0057] During assembly and manufacturing, this invention utilizes an adhesive process to achieve double-sided mounting of PCB boards using the same 63Sn37Pb solder, thus avoiding the risk of component damage caused by excessively high reflow temperatures when using dissimilar solders.

[0058] By applying low-melting-point solder, adhesive, and reflow tooling to the housing steps, the assembly and packaging of the PCB board, RF connector, and double-sided cover plate are achieved, greatly simplifying the component manufacturing process, achieving a high yield, and meeting the needs of mass production. At the same time, by placing solder rings in the V-shaped recessed structure formed after assembly, the metal cover plate and metal shell are welded through the solder rings in the V-shaped recessed structure, and the RF connector and metal shell are welded through the solder ring placement holes, thus ensuring the hermetic packaging of the RF component.

[0059] In summary, the above-mentioned solutions simplify the production process, increase the product yield, and produce miniaturized, hermetically sealed, and highly reliable radio frequency components suitable for mass production.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A high-density metal-packaged radio frequency component, characterized in that, include: The system comprises a metal housing, a PCB board, and an RF connector. The PCB board mounts components on both sides. The metal housing has a through-mount area on its top. The mounting area includes PCB mounting steps and RF signal shielding beams. The PCB board is mounted on the PCB mounting steps. The metal housing has mounting platforms along the edges of the mounting area on both its top and bottom surfaces, each with a metal cover plate. The side of the metal housing has an RF connector mounting through-hole, with a solder ring mounting groove at the axial end edge of the through-hole. The RF connector is fixedly mounted within the through-hole. The top and bottom surfaces of the metal housing have 45° chamfers adjacent to the corresponding metal cover plates. The edges of the metal cover plates also have 45° chamfers. The chamfers on the top and bottom surfaces of the metal housing, when assembled with the chamfers at the edges of the corresponding metal cover plates, form a V-shaped recessed structure. The RF connector has a positioning plug at the bottom of its mounting hole; during installation, the RF connector is positioned using the positioning plug at the bottom of its mounting hole and the adhesive applied to the external end. The radio frequency signal shielding beam and PCB mounting steps are equipped with solder paste receiving grooves. Components, PCB boards, metal tube shells, cover plates, and radio frequency connectors are all installed and connected by reflow soldering to achieve the airtightness of the packaging structure.

2. A method for assembling a high-density metal-packaged radio frequency component, wherein the assembly method is applied to the high-density metal-packaged radio frequency component according to claim 1, characterized in that, include: S1: PCB board mounting. Select the side of the board with lighter components or fewer components as the first side. Reflow solder the components on the first side of the PCB board using 63Sn37Pb solder. Then reflow solder the components on the second side of the PCB board using the same 63Sn37Pb solder. S2: Apply low-melting-point solder paste to the solder paste receiving tank of the PCB mounting step and RF signal shielding beam in the metal tube; and use tweezers to insert the PCB board into the metal tube and press it lightly to make it fully fit with the PCB mounting step. S3: Insert the RF connector into the RF connector mounting through hole, install the solder ring in the solder ring placement hole, and apply adhesive to cover the solder ring, RF connector, and metal housing. S4: Install metal cover plates on the cover plate mounting platforms on both the upper and lower sides of the metal tube shell, and place a solder ring in the V-shaped groove structure formed after assembly. After placement, use a clamp to hold and fix it. S5: Place the assembled product from step S4 into a reflow oven for reflow soldering. After soldering, remove the fixture to obtain the assembled RF component.

3. The assembly method of a high-density metal-packaged radio frequency component according to claim 2, characterized in that, Before reflow soldering the components on the second side of the PCB, reinforce the junction between the heavy components weighing more than 2g on the first side of the PCB and the printed circuit board by applying red glue or spot-applying epoxy glue.

4. The assembly method of a high-density metal-packaged radio frequency component according to claim 2, characterized in that, The peak temperature of the reflow curve during PCB board mounting is 40-60°C higher than the melting point of the solder paste, and the holding time is 40-70 seconds; the heating rate at any time shall not exceed 4°C / s, and the cooling rate during the cooling phase shall not exceed 5°C / s.

5. The assembly method of a high-density metal-packaged radio frequency component according to claim 2, characterized in that, The low-melting-point solder paste includes SnAg, InSn, or SnBi.

6. The assembly method of a high-density metal-packaged radio frequency component according to claim 2, characterized in that, After step S2 is completed, the connection points between the RF connector and the PCB board pads are soldered using SAC305 solder.

7. The assembly method of a high-density metal-packaged radio frequency component according to claim 2, characterized in that, In step S5, the peak temperature during reflow soldering does not exceed 185°C, and the reflow chain speed is lower than that during PCB board mounting.

8. The assembly method of a high-density metal-packaged radio frequency component according to claim 2, characterized in that, When the adhesive in step S3 is red glue, after the reflow soldering in step S5 is completed, the RF component is placed on a 120°C heating table to fully preheat the metal housing, and then the softened red glue in step S3 is scraped off with a blade.

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