Installation method and system for isolating complex installation stress of printed circuit board

Abstract

The invention belongs to the technical field of electronic device assembly protection, and discloses an installation method and system for isolating complex installation stress of a printed circuit board, and the method comprises the steps: arranging a groove with a structure with a large inner part and a small outer part on an installation substrate, and employing a specifically designed flexible connection column, and at least two annular clamping parts are arranged on the column body of the connecting column and are respectively clamped with the groove of the substrate and the through hole of the printed circuit board in an interference fit manner. The system comprises a mounting substrate with a groove, a flexible connecting column and a printed circuit board with a through hole. Through the elastic deformation of the flexible connecting column, the printed circuit board is quickly and reliably fastened, complex stress generated by non-conformal mounting planes, mechanical vibration and mismatch of thermal expansion coefficients of different materials is effectively isolated and absorbed, and the flexible connecting column is particularly suitable for mounting protection of precision electronic devices sensitive to mechanical stress and has a wide application prospect. And the problems caused by a traditional screw fastening or gluing mode are avoided.

Description

Technical Field

[0001] This invention belongs to the field of electronic device assembly protection technology, specifically relating to an installation method and installation system for protecting printed circuit boards and stress-sensitive components soldered on them under harsh mechanical and thermal environments. Background Technology

[0002] In modern electronic devices, printed circuit boards (PCBs) are the core carriers that support various electronic components. Typically, PCBs are directly fastened to the device housing or mounting bracket using screws. However, this rigid connection method has inherent drawbacks: First, when there are flatness errors on the mounting surface, forcibly tightening the screws will generate static installation stress, causing the PCB to bend; second, during device operation, dynamic loads such as vibration and impact will cause the rigid connection to directly transfer stress to the PCB; third, when the ambient temperature changes, the significant difference in the coefficients of thermal expansion between the PCB material (such as FR-4) and the mounting substrate material (such as aluminum or steel) will generate enormous thermal stress.

[0003] These complex static and dynamic stresses are extremely detrimental to many stress-sensitive components soldered on the board (such as large-size BGA packaged chips, high-precision crystal oscillators, MEMS sensors, ceramic capacitors, etc.), causing performance drift, reliability degradation, or even direct damage.

[0004] To address the aforementioned issues, existing technologies have employed methods such as using rubber gaskets or rubber adhesives for cushioning and fixation. However, rubber gaskets typically require the use of screws, offering limited cushioning and failing to resolve thermal stress issues. Furthermore, rubber adhesives involve complex curing processes, long production cycles, and difficulty in controlling post-curing consistency, causing significant inconvenience for subsequent maintenance and making them unsuitable for the large-scale, high-efficiency automated production needs of the electronics industry.

[0005] Therefore, there is an urgent need in this field for a PCB mounting solution that can be installed quickly and reliably, effectively isolate various complex stresses, and facilitate maintenance and replacement. Summary of the Invention

[0006] The primary objective of this invention is to provide an installation method for isolating complex installation stresses on printed circuit boards. This method enables screwless, rapid installation and removal of PCBs, and effectively absorbs and isolates installation stress, vibration, and thermal stress by utilizing the deformation of elastic elements. It solves the problems of installation stress inevitably generated by existing screw-fastening installation methods, and the complex operation, long waiting time, and poor uniformity of traditional rubber bonding methods.

[0007] Another object of the present invention is to provide an installation system for implementing the above method, which system should be simple in structure, convenient to assemble, have good consistency, and be suitable for automated production.

[0008] The technical solution of the present invention is realized as follows: In a first aspect, the present invention provides an installation method for isolating complex installation stresses of a printed circuit board, which comprises the following steps: Provide an installation substrate, and prepare one or more installation grooves on the installation substrate; Provide one or more flexible connecting columns made of an elastic material, wherein at least two annular engaging portions distributed along the axial direction are provided on the column body of the flexible connecting column, so as to form at least one upper engaging structure and at least one lower engaging structure on the column body; Press and snap the lower engaging structure of the flexible connecting column into the installation groove of the installation substrate; Provide a printed circuit board, and one or more installation through holes corresponding to the positions of the flexible connecting columns are provided on the printed circuit board; Align the installation through holes of the printed circuit board with and press them into the upper engaging structure of the flexible connecting column, so that the flexible connecting column fastens the printed circuit board to the installation substrate through its elastic deformation, and the elasticity of the flexible connecting column is used to isolate and absorb the installation stress and thermal stress between the printed circuit board and the installation substrate.

[0009] Its core steps include: S1: Preparation of the installation substrate. On the installation substrate (usually made of metal, such as aluminum alloy) of the device, one or more installation grooves are prepared by mechanical processing (such as milling, drilling) or die-casting. The key feature of the groove is that its structure is "larger inside and smaller outside", for example, it can be a chamfered cylindrical groove with a limiting lip at the opening, or a dovetail groove structure. This structural design aims to form an interlock with the subsequent flexible connecting column.

[0010] S2: Preparation of the flexible connecting column. Provide a flexible connecting column made of an elastic material. The cross-section of the connecting column is preferably circular, and at least two annular engaging portions distributed along the axial direction are integrally formed on its column body by a molding process. These annular engaging portions make the column body present a profile similar to the shape of the Chinese character "king" macroscopically, thus naturally forming at least one upper engaging structure and at least one lower engaging structure. The diameter of the column body part between the upper and lower engaging structures is smaller than the maximum outer diameter of the engaging portion, and this area constitutes the main elastic deformation area.

[0011] S3: Substrate-side installation. Align the lower engaging structure of the flexible connecting column with the groove of the mounting substrate and press it into the groove. Due to the "larger inner diameter and smaller outer diameter" structure of the groove and the elasticity of the connecting column material, the lower engaging structure will undergo compressive deformation and pass through the narrow opening of the groove, and then recover its deformation and be stuck inside the groove, forming a firm and axially non-detachable connection.

[0012] S4: Printed circuit board installation. Align the preset mounting through-hole on the printed circuit board with the upper engaging structure of the flexible connecting column already installed on the substrate, and then press it down. The upper engaging structure also undergoes elastic deformation due to interference fit until the bottom surface of the PCB contacts the shoulder or the middle cylinder of the connecting column. At this time, the upper engaging structure recovers its deformation and is stuck above the mounting through-hole of the PCB, thereby reliably fixing the PCB above the mounting substrate.

[0013] As a further technical solution of the present invention: The mounting groove on the mounting substrate is a chamfered cylindrical groove or a dovetail groove structure with an inner cavity diameter larger than the opening diameter, and the lower engaging structure of the flexible connecting column is adapted to the shape of the groove to form an interlocking fit.

[0014] As a further technical solution of the present invention: The cross-section of the flexible connecting column is circular, and its overall structure is a "king" shape. The upper engaging structure and the lower engaging structure are formed by the annular engaging portion; the upper engaging structure has an interference fit with the mounting through-hole of the printed circuit board, and the lower engaging structure has an interference fit with the mounting groove of the mounting substrate.

[0015] As a further technical solution of the present invention: The material of the flexible connecting column is one of silicone rubber, fluorosilicone rubber, polyurethane elastomer or nitrile rubber.

[0016] As a further technical solution of the present invention: The diameter of the middle cylinder part between the upper engaging structure and the lower engaging structure of the flexible connecting column is smaller than the maximum outer diameter of the upper engaging structure and the lower engaging structure, and this middle cylinder part constitutes the main elastic deformation area.

[0017] As a further technical solution of the present invention: The size design of the flexible connecting column satisfies that under the action of the expected maximum installation stress or thermal stress, the maximum shear strain generated by the middle cylinder part of the flexible connecting column is less than 50% of the yield limit of its material.

[0018] As a further technical solution of the present invention: The inner diameter of the flexible connecting column is not less than 2 mm, and its overall height matches the installation distance between the printed circuit board and the mounting substrate.

[0019] Second aspect, the present invention provides a stress isolation installation system, which includes: <00000The mounting base plate has one or more mounting grooves with an inner large and outer small structure; One or more flexible connecting posts, made of elastic material, are provided with at least two axially distributed annular engaging portions on the post body, forming an upper engaging structure for engaging printed circuit boards and a lower engaging structure for engaging mounting substrates. A printed circuit board having one or more mounting through holes for engaging with the upper engaging structure of the flexible connecting post; The lower engaging structure of the flexible connecting post is engaged in the mounting groove of the mounting substrate, and the printed circuit board is engaged in the upper engaging structure of the flexible connecting post through its mounting through hole, thereby achieving fastening and stress isolation through the elastic deformation of the flexible connecting post.

[0020] Mainly includes: Mounting base plate: As a supporting structure of the system, it is provided with at least one mounting groove with a "larger inside and smaller outside" feature. The opening of the groove is preferably provided with a guide chamfer to facilitate the pressing in of the flexible connecting post.

[0021] Flexible connecting pillars: As a core functional component of the system, they are made of elastic materials with specific hardness (such as silicone rubber with a Shore A rating of 40-60) and have a pillar-like structure with annular interlocking parts. Their dimensions (such as inner diameter and height) and quantity need to be calculated and configured based on the weight and size of the PCB and the expected environmental loads (such as impact, vibration levels, and temperature range).

[0022] Printed circuit board: It has mounting through holes that match the position and size of the flexible connecting posts.

[0023] As a further technical solution of the present invention: the opening of the mounting groove of the mounting substrate is provided with a guide chamfer, and the edge of the lower engaging structure of the flexible connecting column is provided with a mating chamfer to facilitate press-fit alignment.

[0024] As a further technical solution of the present invention: the material hardness of the flexible connecting post is between Shore A 30 and 70 degrees, and its size and quantity are configured according to the weight, size and impact vibration load to be resisted of the printed circuit board.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Excellent stress isolation capability: The elastic deformation zone of the flexible connecting column can effectively buffer and absorb stress from three directions: installation pressure and impact on the Z-axis, vibration and shear force on the XY plane, and thermal stress caused by CTE mismatch, providing comprehensive protection for sensitive components on the PCB.

[0026] 2. Quick assembly and maintenance: The entire installation process requires no tools and only simple pressing operations, greatly improving the assembly efficiency and being especially suitable for automated production lines. When maintenance is needed, simply pull up the PCB to complete disassembly. The connecting columns and the substrate can be reused, and the maintenance cost is extremely low.

[0027] 3. High reliability and consistency: The use of adhesives is abandoned, avoiding the consistency problems and unstable factors brought by the curing process. The mechanically interlocked structure is stable and reliable, with good performance consistency.

[0028] 4. Flexible design: The size, hardness, and quantity of the flexible connecting columns can be flexibly designed and arranged according to specific application scenarios to meet the application requirements in different fields from consumer electronics to aerospace.

[0029] 5. High cost-effectiveness: The structure is simple, suitable for large-scale injection molding production, and the cost of each part is low. At the same time, the improvement of assembly efficiency and product qualification rate brings a decrease in the overall cost.

[0030] The following further describes the present invention in detail with reference to the accompanying drawings of the embodiments. Brief Description of the Drawings

[0031] Figure 1 is a schematic cross-sectional structure diagram of the installation system of the present invention.

[0032] Figure 2 is a three-dimensional exploded view of the installation system of the present invention.

[0033] Figure 3 is a separate schematic diagram of the flexible connecting column (the "king" - shaped structure) of the present invention.

[0034] Figure 4 is a partially enlarged schematic diagram of the grooved structure with a guiding chamfer on the installation substrate.

[0035] Explanation of the reference numerals in the drawings: 1 - installation substrate, 2 - printed circuit board, 3 - "king" - shaped rubber column. Detailed Embodiment

[0036] To make the purpose, technical solutions, and advantages of the implementation of the present invention clearer, the technical solutions in the embodiments of the present invention will be described in more detail below with reference to the accompanying drawings in the embodiments of the present invention. In the drawings, the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The described embodiments are part of the embodiments of the present invention, not all of the embodiments.

[0037] The embodiments described below by referring to the drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0038] Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0039] The following will describe the embodiments of the present invention in detail with reference to the accompanying Figure 1-4 drawings.

[0040] Embodiment 1 The embodiment of the present invention discloses the installation of a MEMS sensor printed circuit board in a certain high-precision inertial navigation unit.

[0041] In a certain inertial navigation unit, the core sensor board is welded with high-precision MEMS gyroscopes and accelerometers. These sensors are extremely sensitive to board-level mechanical stress. Originally, M3 screws were used for four-point fastening on an aluminum housing. During the temperature cycle test (-40°C to +85°C), due to the CTE difference between the FR-4 board and the aluminum housing, the sensor output signal showed unacceptable drift. At the same time, during the vibration test, the rigid connection amplified the vibration response in a specific frequency band.

[0042] The implementation scheme of the present invention: Step 1: System design and part preparation.

[0043] Mounting substrate 1: That is, the aluminum alloy housing of the device. On its bottom plate plane, 4 mounting grooves are machined using a CNC milling machine. The grooves are chamfered cylindrical, with a bottom cavity diameter of 6.0 mm. Due to the limiting lip at the opening, the diameter is reduced to 5.0 mm, and the total depth of the groove is 2.5 mm. A 0.2 mm C chamfer is machined at the opening as a guiding chamfer ( Figure 4 ).

[0044] Flexible connection column 3: Entrust a rubber products factory to form it by a molding process using fluorosilicone rubber with a Shore A hardness of 50 degrees. Its structure is a standard "king" shape ( Figure 3 ). Lower clamping structure: The outer diameter is 5.2 mm and the height is 1.0 mm. It is designed to have an interference fit with the substrate groove (opening 5.0 mm).

[0045] Upper clamping structure: The outer diameter is 5.2 mm and the height is 1.0 mm.

[0046] Middle elastic deformation area: The diameter is 3.0 mm and the height is 4.0 mm. This area is the main deformation and energy absorption part.

[0047] Inner diameter: A through hole passing through the center of the column body, with a diameter of 2.5 mm, used to provide additional deformation space during press-fitting and reduce the press-fitting force.

[0048] Printed Circuit Board 2: The PCB thickness of this sensor is 1.6mm. At its four corners, there are circular mounting holes with a diameter of 5.0mm, which form an interference fit with the snap-fit ​​structure (5.2mm) on the connecting post.

[0049] Step 2: Assembly process.

[0050] Housing pretreatment: Clean the grooves on the aluminum alloy housing to ensure there is no oil or debris.

[0051] Install the connecting posts: The operator or automated equipment vertically aligns the lower locking structure of the four fluorosilicone rubber flexible connecting posts 3 with the grooves on the housing 1, and then applies a force of approximately 5 kgf to press them into place one by one. A slight "click" sound or a feeling of them being in place indicates that the lower locking structure has successfully engaged in the groove.

[0052] PCB Installation: Align the four mounting holes of sensor PCB2 with the upper locking structure of the four pre-installed connecting posts. Then, press the PCB down evenly until its bottom surface contacts the upper end of the elastic deformation zone in the middle of the connecting posts. At this point, the upper locking structure has deformed and passed through the PCB through holes, and then returns to its original shape from above, reliably locking the PCB in place.

[0053] Effect verification: Temperature cycling test: In the same temperature cycle from -40℃ to +85℃, the zero-bias output stability of the MEMS sensor was improved by about 70%, and the signal drift caused by thermal stress was significantly suppressed.

[0054] Random vibration test: Under the vibration spectrum of 10-2000Hz, the resonant peak acceleration of the PCB decreased by about 50%, and the vibration energy transmitted to the sensor was greatly reduced.

[0055] Assembly efficiency: Compared with the original screw fastening, the assembly time is reduced by about 60%, and stress differences caused by inconsistent screw torque are completely avoided.

[0056] Maintainability: During subsequent debugging, when a PCB needed to be replaced, the disassembly and installation of the new board were completed in less than 1 minute, demonstrating excellent maintainability.

[0057] This invention provides a highly efficient, reliable, and low-cost PCB stress isolation solution through ingenious mechanical structure design and the application of elastic material mechanics, and is especially suitable for high-end electronic equipment fields with stringent requirements for reliability and environmental adaptability.

[0058] Example 2 This embodiment takes the installation of a high-performance FPGA chip, which is extremely sensitive to vibration and thermal stress, on a printed circuit board in a certain type of airborne radar signal processing module as an application scenario, and describes in detail the entire installation process, key parameters, and verification results.

[0059] Example: Stress-isolated mounting of FPGA printed circuit board in airborne radar signal processing module 1. Problem Background and Requirements Analysis: Equipment: A certain type of airborne radar signal processing module.

[0060] Core component: A 12-layer high-frequency PCB (printed circuit board 2) with a Xilinx UltraScale+ series large FPGA, 2.4mm thick and 200mm x 150mm in size.

[0061] challenge: Mechanical vibration: The airborne environment has wide-bandwidth, high-intensity random vibrations. Traditional screw tightening can easily cause PCB resonance, leading to fatigue fracture of BGA solder joints.

[0062] Thermal stress: When the module is working, the FPGA power consumption can reach 40W, causing local temperature rise on the PCB. The mounting substrate 1 (aluminum alloy housing) serves as a heat dissipation path, and there is a mismatch in the coefficients of thermal expansion between it and the PCB of approximately 14 ppm / °C (FR-4) and 23 ppm / °C (Al), which generates huge alternating thermal stress during temperature cycling (-55°C to +105°C).

[0063] Mounting flatness: The flatness error of large-area aluminum alloy housings is usually in the range of 0.1-0.2mm. Tightening screws will convert this into bending stress on the PCB.

[0064] 2. Detailed design and fabrication of the stress isolation installation system of the present invention: Step 201: Design and fabrication of mounting substrate 1.

[0065] Substrate: 6061-T6 aluminum alloy, heat-treated to stabilize dimensions and mechanical properties.

[0066] Recessed design: Layout: Based on the weight of the FPGA board (approximately 150g) and dynamic simulation analysis, it was determined that 8 flexible connecting pillars 3 would be used, distributed under the PCB in a "four-point support, central reinforcement" layout.

[0067] Structure: Each mounting point is machined with a "beveled cylindrical groove". This groove consists of two parts: Bottom cavity: diameter Φ6.5+0.05 / 0mm, depth 2.0mm.

[0068] Limiting lip: The diameter of the opening is Φ5.2+0.05 / 0mm, and the height is 0.5mm.

[0069] Guiding feature: A guiding chamfer of 0.3x45° is machined at the edge of the lip to guide the smooth pressing of the connecting column.

[0070] Processing technology: Using a CNC precision milling machine, first use a flat-end milling cutter with a diameter of Φ5.2mm to mill the lip, and then change to a milling cutter with a diameter of Φ6.5mm to mill the bottom cavity. After processing, the groove is sandblasted (100-mesh white corundum) and anodized to enhance surface hardness, wear resistance and adhesion to rubber (although not necessary, it is beneficial). <00,00176>

[0071] Step 202: Design and preparation of the flexible connecting column 3.

[0072] Material selection: After comprehensive evaluation, fluorosilicone rubber with a Shore A hardness of 55±5 is selected. This material combines the wide temperature range (-60°C to +200°C) and excellent elasticity of silicone rubber, as well as better fuel and chemical resistance than ordinary silicone rubber, making it very suitable for the airborne environment.

[0073] Structural design (refer to Figure 3 ) : Adopt the standard "king" - shaped integrated structure, and the specific dimensions are as follows: Lower clamping structure: Outer diameter: Φ5.4 - 0.1 / 0mm (forming an interference fit of about 0.2mm with the lip of the substrate groove Φ5.2mm).

[0074] Height: 1.2mm.

[0075] An inlet angle of 0.2x45° is designed at the upper edge.

[0076] Upper clamping structure: Outer diameter: Φ5.4 - 0.1 / 0mm (forming an interference fit of about 0.4mm with the PCB through - hole Φ5.0mm).

[0077] Height: 1.2mm.

[0078] An inlet angle of 0.2x45° is designed at the lower edge.

[0079] Middle elastic deformation zone: Diameter: Φ3.5±0.1mm.

[0080] Height: 5.0mm. This area is the core part for absorbing vibration energy and compensating for thermal expansion differences.

[0081] Central through - hole: Runs through the entire connecting column with a diameter of Φ2.0mm. This hole is crucial as it allows the connecting column to deform inward when compressed, not just outward, significantly reducing the press - fitting force and providing additional deformation space to handle larger displacements. [[ID=!8]]

[0082] Manufacturing process: Precision injection molding is used. The mold cavity precision requirement is ISO3302-1 Class 2. After molding, a second vulcanization is performed to eliminate internal stress and stabilize material properties. 100% visual inspection and sampling inspection of key dimensions are carried out on the finished products.

[0083] Step 203: Preparation of printed circuit board 2.

[0084] Through-hole design: Non-metallic mounting through-holes with a diameter of Φ5.0+0.1 / 0mm are designed at the 8 corresponding mounting positions on the PCB.

[0085] Peripheral design: On the PCB, a component-free area with a diameter of not less than Φ8mm is reserved around each mounting through hole to ensure that the connecting post has enough space when deformed and will not collide with surrounding components.

[0086] 3. Precision assembly process flow: Step 301: Preparation.

[0087] Environment: Conducted in a cleanroom with a temperature of 23°C ± 2°C and a humidity of 40%-60%.

[0088] Cleaning: Use high-purity isopropyl alcohol and a lint-free cloth to thoroughly clean the grooves of the mounting substrate 1, the surface of the flexible connecting post 3, and the mounting through holes of the printed circuit board 2.

[0089] Step 302: Installation of flexible connecting post 3 (to the substrate).

[0090] Tools: Use a custom-made small vacuum pen or a robotic arm with soft grippers to pick up and place the connecting posts to avoid damage.

[0091] operate: Align the guide angle of the lower locking structure of the connecting post 3 with the guide chamfer of the groove in the substrate 1.

[0092] Apply a vertically downward force to slowly and steadily press the connecting post into the groove.

[0093] Pressing force monitoring: The process is verified using a press equipped with a force sensor. The pressing force of a single connecting column is approximately 15-25N. When the force value felt by hand or displayed on the equipment suddenly drops, it indicates that the lower locking structure has passed the lip and locked into the bottom cavity, and is installed in place.

[0094] Check that the connecting post is perpendicular to the substrate plane and that its bottom is in full contact with the bottom surface of the groove.

[0095] Step 303: Installation of printed circuit board 2.

[0096] Alignment: Lift PCB2 horizontally and align its 8 mounting through holes precisely with the upper engagement structure of the 8 connecting posts already mounted on the substrate.

[0097] Pressing: A parallel pressing stage with multi-point pressure feedback is used. The indenter plane has a soft polyurethane pad to ensure uniform pressure distribution.

[0098] Slowly press down on the PCB at a speed of 1-5mm / s.

[0099] When the bottom surface of the PCB contacts the upper surface of the middle elastic deformation zone of the connecting post, the pressure will begin to rise linearly. Continue pressing down until the PCB is fully supported and the pressure feedback at each connection point is stable.

[0100] Total pressing force: It has been verified that the total pressing force at 8 points is approximately 80-120N.

[0101] Final inspection: After installation, the PCB should be visually inspected for flatness and no warping. Gently twist the PCB by hand; it should feel firmly supported and elastic, without any looseness. The upper locking mechanism should be clearly visible above the PCB through-holes.

[0102] 4. Verification Testing and Effect Analysis: Mechanical vibration testing: Conditions: Random vibration tests were conducted according to MIL-STD-810G, Method 514.7, Procedure I (helicopter-borne).

[0103] Results: An accelerometer was installed at the center of the PCB. Compared to the original screw-fastening method, the first-order resonant frequency of the PCB decreased from approximately 450Hz to approximately 180Hz. More importantly, the amplification factor (Q value) at the resonant frequency was significantly reduced by approximately 70%. This means that the dynamic stress transmitted to the FPGA BGA solder joints is greatly reduced. After vibration testing, X-ray inspection showed no cracks in the BGA solder joints.

[0104] Thermal cycling test: Conditions: -55°C to +105°C, 500 cycles.

[0105] Results: Measured using strain gauges attached to the PCB surface. Under the original screw-based method, the central region of the PCB experienced periodic tensile and compressive stresses exceeding 800 microstrains. With this invention, the strain value decreased to below 150 microstrains, achieving a strain isolation efficiency exceeding 80%. The FPGA's operational stability at high temperatures was significantly improved, and the logic error rate decreased.

[0106] Assembly and maintainability: Assembly time: Reduced from approximately 3 minutes (tightening 8 screws and checking torque) to approximately 30 seconds (one-time pressing).

[0107] Disassembly and Reassembly: To verify maintainability, 10 disassembly-reassembly cycles were carried out. After each disassembly, the connecting columns were inspected and no visible damage or permanent deformation was found. The vibration and thermal performance after reassembly showed no significant difference from the newly installed state.

[0108] Conclusion: This specific embodiment fully demonstrates that the stress isolation installation method and system provided by the present invention, through careful material selection, structural design and process control, successfully solve the reliability problem of the PCB in high-end electronic devices caused by complex installation stress. It not only provides excellent dynamic and static stress isolation performance, but also achieves rapid assembly and convenient maintenance, and has extremely high engineering application value.

[0109] Embodiment 3 The embodiment of the present invention discloses a method for isolating complex installation stress of a printed circuit board that is easy to install. By converting the original screw fastening installation method into a flexible rubber column press-fitting method, it can ensure the installation strength, and can be installed quickly, improve the product assembly efficiency, and can rely on the micro-deformation of the rubber column to eliminate the installation stress and improve the environmental adaptability of the printed circuit board. The steps include: (1) Process a cylindrical groove with a larger inner diameter and a smaller outer diameter on the printed board mounting substrate; (2) Process the rubber material into a "king" - shaped cylinder, which contains two grooves on the upper and lower sides and can respectively hold the through holes of the printed board and the grooves of the mounting base; (3) Press the lower layer of the card slot of the "king" - shaped rubber column into the groove of the mounting substrate; (4) Press the printed circuit board into the upper layer of the card slot of the "king" - shaped rubber column to fasten the printed circuit board and the mounting substrate; Through the above steps, the stress - sensitive printed circuit board can be installed quickly. While fastening the printed board, it can also rely on the micro - deformation of the rubber column to eliminate the installation stress generated during the installation process or the temperature change process, and improve the performance and environmental adaptability of stress - sensitive devices.

[0110] Furthermore, the height of the grooves at both ends of the "king" - shaped rubber column is slightly smaller than the thickness of the printed board and the thickness of the groove of the mounting substrate, so that the "king" - shaped rubber column can tightly press the printed board and the mounting substrate.

[0111] The thickness of the spacer is 300 microns, and the thickness can be adjusted within the range of 50 microns to 400 microns, which needs to be determined according to the magnitude of the installation stress and the temperature stress, and the shear strain of the formed rubber column under the action of stress or temperature should be less than 50% Furthermore, the sizes of the "king" - shaped rubber column, the through holes of the printed board, and the grooves of the mounting substrate can be adjusted according to the size of the printed board. The inner diameter of the "king" - shaped rubber column is usually not less than 2 mm.

[0112] Furthermore, the material of the "king" - shaped rubber column can be selected from deformable elastic materials such as silicone rubber, epoxy glue or capacitive glue.

[0113] In order to solve the problems that the existing screw fastening installation method will inevitably generate installation stress, and the traditional rubber bonding method is complex in operation, requires a long waiting time, and has poor uniformity, the present invention proposes a method for isolating the complex installation stress of a printed circuit board that is easy to install. By converting the original screw fastening installation method into a flexible rubber column press - fitting method, the flexible rubber column is a special "king" - shaped one. Its upper end can hold the printed board, and its lower end can be stuck in the groove of the mounting substrate. Using this method can quickly install stress - sensitive printed circuit boards. While fastening the printed board, it can also rely on the micro - deformation of the rubber column to eliminate the installation stress generated during the installation process or the temperature - change process, improve the performance and environmental adaptability of stress - sensitive devices. The following gives typical operation steps.

[0114] The present invention has the following effects: The present invention proposes a method for isolating the complex installation stress of electronic devices. Electronic devices are usually welded on printed boards and then fastened to various installation structures through mounting screws. However, the direct fastening method will generate relatively large installation stress due to problems such as the fitting degree of the installation plane and temperature change. For stress - sensitive electronic devices, it will significantly affect their performance and use. This method is to convert the original screw fastening installation method into a flexible rubber column installation method. It can, while ensuring the installation strength, rely on the micro - deformation of the rubber column to eliminate the installation stress, and at the same time avoid problems such as rubber curing. It is simple in operation, fast in assembly speed, and good in uniformity, and can meet the requirements of mass assembly production in the electronics industry.

[0115] Thus, the object of the present invention is achieved.

[0116] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A mounting method for isolating complex mounting stresses of a printed circuit board, characterized in that The method comprises the following steps: providing a mounting substrate (1) on which one or more mounting grooves are prepared; providing one or more flexible connecting columns (3) made of elastic material, the column body of the flexible connecting column (3) being provided with at least two annular clamping portions distributed in the axial direction, thereby forming at least one upper clamping structure and at least one lower clamping structure on the column body; pressing and clamping the lower clamping structure of the flexible connecting column (3) into the mounting groove of the mounting substrate (1); providing a printed circuit board (2) provided with one or more mounting through holes corresponding to the positions of the flexible connecting column (3); aligning and pressing the mounting through hole of the printed circuit board (2) into the upper clamping structure of the flexible connecting column (3), so that the printed circuit board (2) is fastened to the mounting substrate (1) by the elastic deformation of the flexible connecting column (3), and the elasticity of the flexible connecting column (3) is used to isolate and absorb the mounting stress and thermal stress between the printed circuit board (2) and the mounting substrate (1).

2. The mounting method for isolating complex mounting stresses of a printed circuit board according to claim 1, characterized in that The mounting groove on the mounting substrate (1) is a chamfered cylindrical groove or a dovetail groove structure with an inner cavity diameter greater than an opening diameter, the lower clamping structure of the flexible connecting column (3) is matched with the shape of the groove to form an interlocking fit.

3. The mounting method for isolating complex mounting stresses of a printed circuit board according to claim 1, characterized in that, The cross section of the flexible connecting column (3) is circular, and the whole is in the shape of a "king" character, the upper clamping structure and the lower clamping structure are formed by the annular clamping portions; the upper clamping structure is in interference fit with the mounting through hole of the printed circuit board (2), and the lower clamping structure is in interference fit with the mounting groove of the mounting substrate (1).

4. The method of claim 1, wherein the method further comprises: The material of the flexible connecting column (3) is one of silicone rubber, fluorosilicone rubber, polyurethane elastomer or nitrile rubber.

5. The method of claim 1, wherein the method further comprises: The diameter of the intermediate column body portion between the upper clamping structure and the lower clamping structure of the flexible connecting column (3) is less than the maximum outer diameter of the upper clamping structure and the lower clamping structure, and the intermediate column body portion constitutes the main elastic deformation area.

6. The method of claim 1, wherein the method further comprises: The flexible connecting column (3) is designed in size to meet the requirement that the maximum shear strain generated in the intermediate column body portion of the flexible connecting column (3) under the action of the maximum expected mounting stress or thermal stress is less than 50% of the yield limit of the material thereof.

7. The method of claim 1, wherein the method further comprises: The inner diameter of the flexible connecting column (3) is not less than 2 mm, and the overall height thereof is matched with the mounting spacing between the printed circuit board (2) and the mounting substrate (1).

8. A stress isolation mounting system for implementing the method of any of claims 1-7, characterized by The method comprises: a mounting substrate (1) provided with one or more mounting grooves with an inner large and outer small structure; one or more flexible connecting columns (3) made of elastic material, the column body of the flexible connecting column (3) being provided with at least two annular clamping portions distributed in the axial direction, thereby forming an upper clamping structure for clamping a printed circuit board and a lower clamping structure for clamping a mounting substrate; a printed circuit board (2) provided with one or more mounting through holes for cooperating with the upper clamping structure of the flexible connecting column (3); and a mounting substrate (1) provided with one or more mounting grooves with an inner large and outer small structure. The lower clamping structure of the flexible connecting column (3) is clamped in the mounting groove of the mounting substrate (1), and the printed circuit board (2) is clamped on the upper clamping structure of the flexible connecting column (3) through the mounting through hole, so that fastening and stress isolation are realized through the elastic deformation of the flexible connecting column (3).

9. The system of claim 8, wherein, A guide chamfer is arranged at the opening of the mounting groove of the mounting substrate (1), and the edge of the lower clamping structure of the flexible connecting column (3) is provided with a matching chamfer, so as to facilitate the press-fitting alignment.

10. The system of claim 8, wherein, The material hardness of the flexible connecting column (3) is between 30 and 70 degrees of Shore A, and the size and number thereof are configured according to the weight, size and required impact vibration load to be resisted of the printed circuit board (2).

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