Efficient environmental stress screening method and system for sealing type plate-level products

Abstract

The invention relates to an efficient environmental stress screening method and system for sealing type plate-level products. The method comprises the steps that at least one process edge integrally formed with a main PCB is additionally arranged on the edge of the main PCB of a to-be-screened board-level product, and a golden finger is arranged on the process edge; providing an environmental stress screening tool, arranging a golden finger socket with an elastic sheet type contact and an aviation plug, fixing a to-be-screened plate-level product on the environmental stress screening tool, butting one end of the golden finger socket with a golden finger to realize electrical connection, and connecting the other end of the golden finger socket with test equipment through a cable and the aviation plug; performing vibration stress screening on the to-be-screened plate-level product; after the environmental stress screening tool of the to-be-screened plate-level product is detached, the to-be-screened plate-level product is put into a drying temperature box to execute temperature stress circulation; and cutting along the boundary between the process edge and the main PCB by using a numerical control board dividing machine so as to cut off the process edge. And environmental stress screening can be rapidly and efficiently carried out on sealing type plate-level products such as process edges, golden fingers and drying temperature boxes.

Description

Technical Field

[0001] This invention relates to the field of electronic equipment testing technology, and in particular to a method and system for efficient environmental stress screening of sealed plate-level products. Background Technology

[0002] Environmental stress screening is an important reliability engineering technology that actively stimulates and eliminates components and process defects with potential defects in products by applying environmental stresses (such as temperature cycling, vibration, etc.).

[0003] Environmental stress screening of board-level products (sealed board-level products with process edges, gold fingers, and drying ovens) often requires additional test point leads or other dedicated interfaces within the board space to meet the testing requirements during the environmental stress screening process. This results in PCB area redundancy and increases the workload during design, production, and debugging. Before temperature cycling screening, board-level products often need to be coated with conformal coating on the printed circuit board and components to prevent moisture from affecting test results or causing components to become damp. Summary of the Invention

[0004] Therefore, this invention provides an efficient environmental stress screening method and system for sealed plate-level products, which solves the problems of low screening efficiency, redundant plate area, and insufficient targeting of traditional plate-level product environmental stress screening methods. It can quickly and efficiently screen environmental stress for sealed plate-level products such as process edges, gold fingers, and drying ovens.

[0005] To address the aforementioned technical problems, this invention provides a method for efficient environmental stress screening of sealed plate-level products, comprising: At least one process edge integrally formed with the main PCB board is added to the edge of the main PCB board of the product to be screened. One of the process edges is provided with gold fingers. By routing traces at the connection between the process edge and the main PCB board, the signals on the main PCB board are introduced into the gold fingers to realize the electrical connection with external testing equipment. An environmental stress screening fixture is provided, which is equipped with a gold finger socket with spring-loaded contacts and an air connector. The board-level product to be screened is fixed to the environmental stress screening fixture. At the same time, one end of the gold finger socket is connected to the gold finger to achieve electrical connection, and the other end of the gold finger socket is connected to the test equipment through a cable and the air connector. Install the environmental stress screening fixture with the plate-level product to be screened onto the vibration test bench; Vibration stress screening is performed on the board-level products to be screened using the external testing equipment. In response to the completion of vibration stress screening, the environmental stress screening fixture of the plate-level product to be screened is removed and placed in a drying oven to perform temperature stress cycling. In response to the completion of a temperature stress cycle, a CNC depaneling machine is used to cut along the boundary line between the process edge and the main PCB board to remove the process edge.

[0006] In one embodiment of the present invention, the process edge has the same thickness as the main PCB board.

[0007] In one embodiment of the present invention, two process edges are provided, and are respectively provided on the two opposite edges of the main PCB board.

[0008] In one embodiment of the present invention, the environmental stress screening fixture has reserved screw connection holes, and each of the process edges is provided with mounting holes. The screw connection holes and the mounting holes are connected by screws to fix the plate-level product onto the environmental stress screening fixture.

[0009] In one embodiment of the present invention, when performing vibration stress screening on the vibration table, abnormal vibration signal fluctuations are monitored during the screening process.

[0010] In one embodiment of the present invention, the vibration conditions for vibration stress screening include a frequency of 350 Hz, an acceleration of 20 g, and a duration of 5 min.

[0011] In one embodiment of the present invention, when performing temperature stress cycling in the drying oven, abnormal temperature signal fluctuations are monitored during the screening process.

[0012] In one embodiment of the present invention, the temperature range of the temperature stress cycle is -55°C to 125°C, each cycle is 90 minutes, and the number of cycles is 10.

[0013] In one embodiment of the present invention, the cutting accuracy of the CNC PCB splitter is ±0.1mm.

[0014] This invention also provides a high-efficiency environmental stress screening system for sealed plate-level products, used to implement the high-efficiency environmental stress screening method for the sealed plate-level products, the system comprising: The board-level products to be screened include a main PCB board with a process edge, the process edge being integrally formed with the main PCB board and having gold fingers and mounting holes, and signal output being achieved through the connection between the process edge and the main PCB board; An environmental stress screening fixture is provided, which is equipped with a gold finger socket with spring-loaded contacts and an aviation connector. One end of the gold finger socket is electrically connected to the gold finger, and the other end of the gold finger socket is connected to the testing equipment via a cable and the aviation connector. The environmental stress screening fixture also has reserved screw connection holes, and the board-level product is fixed on the environmental stress screening fixture by connecting the screw connection holes and the mounting holes with screws. A vibration table is used to perform vibration stress screening on the plate-level products to be screened, which are fixed on the environmental stress screening fixture. A drying chamber is used to perform temperature stress cycling on the plate-level products to be screened after vibration stress screening. CNC depaneling machine is used to cut and remove the process edge along the boundary line between the process edge and the main PCB board after temperature stress cycling.

[0015] The technical solution of the present invention has the following advantages compared with the prior art: The present invention provides an efficient environmental stress screening method and system for sealed board-level products, which effectively saves the board space of the main PCB board by arranging the clamping structure, electrical connection interface and MARK point on the process edge, so that the main PCB board does not need to reserve extra area for testing and clamping, and the area of ​​the main PCB board can be reduced by about 10%. Compared with traditional lead wire connection methods, this invention adopts a clamping and electrical connection scheme that combines process edge with gold finger plugging, making the clamping and disassembly process faster and more stable, and improving the overall clamping efficiency by more than 80%. This invention eliminates the need for conformal coating on modules during the environmental stress screening and testing phase, avoiding subsequent rework and cleaning processes. This eliminates the conformal coating step in module assembly and production, significantly shortening the overall product production cycle. It can be extended to environmental stress screening scenarios for board-level products in aerospace, aero-engine, and other industrial electronics fields with high reliability requirements, demonstrating good versatility and engineering application value. Attached Figure Description

[0016] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0017] Figure 1 This is a schematic diagram of the process edge and gold finger structure of the main PCB board of the product to be screened.

[0018] Figure 2 This is a schematic diagram of the environmental stress screening tooling structure.

[0019] Figure 3 This is a cross-sectional view of the temperature cycle stress in the drying oven.

[0020] Explanation of reference numerals on the accompanying drawings: 100. Main PCB board; 200, Process edge; 210, Gold fingers; 220, Mounting hole; 300. Environmental stress screening tooling; 310. Gold finger socket; 320. Aviation socket. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0022] In this invention, when directions (up, down, left, right, front, and back) are described, it is only for the convenience of describing the technical solution of this invention, and does not indicate or imply that the technical features referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0023] In this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," "exceeding," etc., are understood to exclude the stated number; "above," "below," "within," etc., are understood to include the stated number. In the description of this invention, the terms "first" and "second" are used only to distinguish technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0024] In this invention, unless otherwise explicitly defined, the terms "setting," "installing," and "connecting" should be interpreted broadly. For example, they can refer to a direct connection or an indirect connection through an intermediate medium; a fixed connection, a detachable connection, or an integrally formed connection; a mechanical connection, an electrical connection, or a connection capable of mutual communication; or the internal connection of two components or the interaction between two components. Those skilled in the art can reasonably determine the specific meaning of the above terms in this invention based on the specific content of the technical solution.

[0025] Example 1 Reference Figure 1 As shown in this embodiment, a high-efficiency environmental stress screening method for sealed plate-level products includes: S1. At least one process edge 200 integrally formed with the main PCB board 100 of the product to be screened is added to the edge of the main PCB board 100. The process edge 200 has the same thickness as the main PCB board 100. One of the process edges 200 is provided with gold fingers 210, and signals on the main PCB board 100 are introduced into the gold fingers 210 through the connection between the process edge 200 and the main PCB board 100 to achieve electrical connection with external testing equipment.

[0026] For example, two process edges 200 are provided, respectively located on opposite edges of the main PCB board 100. The environmental stress screening fixture 300 has pre-drilled screw connection holes, and each process edge 200 is provided with mounting holes 220. The screw connection holes and mounting holes 220 are connected by screws to fix the board-level product onto the environmental stress screening fixture 300.

[0027] S2. Provide an environmental stress screening fixture 300, which is equipped with a gold finger socket 310 with spring-loaded contacts and an air connector 320. Fix the board-level product to be screened to the environmental stress screening fixture 300. At the same time, one end of the gold finger socket 310 is connected to the gold finger 210 to achieve electrical connection. The other end of the gold finger socket 310 is connected to the test equipment through a cable and the air connector 320. S3. Install the environmental stress screening fixture 300 with the plate-level product to be screened onto the vibration test bench; S4. Perform vibration stress screening on the board-level product to be screened using the external testing equipment; during vibration stress screening on the vibration table, monitor abnormal vibration signal fluctuations. Once abnormal fluctuations occur, the external testing equipment can trigger a marker to locate early defects such as cold solder joints, poor connector contact, device resonance failure, and abnormal stress transmission in the sealing structure.

[0028] S5. In response to the completion of vibration stress screening, the environmental stress screening fixture 300 on the plate-level product to be screened is removed and placed in a drying oven to perform temperature stress cycling. The temperature cycle generally includes a periodic repetition of a heating section, a heat preservation section, a cooling section, and a low-temperature heat preservation section; for example, the temperature can be increased and decreased at a preset slope between a preset high temperature and a preset low temperature, and the dwell time and cycle number of each temperature platform can be set.

[0029] During the temperature stress cycling process in the drying oven, abnormal temperature signal fluctuations are monitored during the screening process. Specifically, the oven temperature and key electrical parameters, functional outputs, and communication quality of the board-level products to be screened are recorded simultaneously during temperature changes. It is observed whether any abnormalities occur at a certain temperature point, such as a significant increase in communication error rate after the temperature reaches a certain threshold, abnormal increase in power consumption during the high-temperature platform, or excessive output drift.

[0030] S6. In response to the completion of the temperature stress cycle, a CNC depaneling machine is used to cut along the boundary line between the process edge 200 and the main PCB board 100 to remove the process edge 200.

[0031] By integrally molding a process edge 200 along the edge of the main PCB board 100, the clamping structures, electrical connection interfaces, and MARK points required for environmental stress screening are uniformly arranged on the process edge 200. This eliminates the need for additional test pads, lead interfaces, or clamping areas on the main PCB board 100, avoiding the problem of sacrificing functional layout space for screening from a structural design perspective. As a result, the surface size of the main PCB board 100 can be significantly reduced without affecting the screening function, with the area of ​​the main PCB board 100 reduced by approximately 10%, which is beneficial for the miniaturization and high integration design of sealing modules.

[0032] The electrical connection between the board-level product and the environmental stress screening fixture 300 is achieved by using a process edge 200 and a gold finger 210 for plug-in connection. Compared with traditional methods such as flying wires, soldering wires, or temporary pin leads, this method avoids the time consumption and consistency problems caused by wiring one wire at a time, manual soldering, or repeated disassembly and assembly. The gold finger 210 and the spring-loaded socket can complete multiple signal, power, and ground connections with a single plug-in. The clamping and disassembly process has a high degree of standardization, and the overall clamping efficiency is improved by more than 80%, significantly improving the production cycle of the environmental stress screening process.

[0033] The process edge 200 is integrally formed with the main PCB board 100 and has the same thickness, ensuring that the gold finger 210 area maintains the same mechanical and thermal response as the motherboard under vibration and temperature stress, avoiding stress concentration problems caused by thickness differences or secondary structures. Combined with the spring-loaded gold finger socket 310 and screw-fixed fixture structure, it can maintain stable contact pressure continuously in vibration table and drying chamber environments, significantly reducing the risk of contact resistance fluctuations, instantaneous disconnections, or poor connections. This ensures the authenticity and repeatability of online monitoring data during vibration stress screening and temperature stress cycling.

[0034] During both vibration stress screening and temperature stress cycling, the board-level product to be screened is kept electrically connected to the external testing equipment, enabling real-time functional monitoring under power-on conditions. By simultaneously monitoring electrical parameters, functional outputs, and communication status during vibration and temperature stress loading, potential defects such as solder joint defects, poor connector contact, device resonance failure, parameter drift, and abnormal stress transmission in the sealing structure can be more easily exposed in advance, thereby improving the ability of environmental stress screening to induce early failures.

[0035] Since the electrical connections and clamping during the environmental stress screening stage are all completed through process edge 200, this invention can meet the vibration and temperature cycling test requirements without applying conformal coating to the module body during the screening and testing stages. This avoids the problem of having to apply conformal coating in advance to prevent the leads from getting damp or short-circuiting, as is required in traditional solutions. This eliminates the need for conformal coating, rework cleaning, and curing waiting processes during module assembly and production, significantly shortening the overall production cycle and reducing manufacturing costs.

[0036] After environmental stress screening and temperature stress cycling are completed, this invention uses a CNC depaneling machine to precisely cut along the boundary line between the process edge 200 and the main PCB board 100, completely removing the process edge 200. The cutting precision is high, and the edge quality is controllable, without adversely affecting the structure, component soldering, or sealing performance of the main PCB board 100. This restores the screened board-level product to its final delivery form, balancing screening reliability with product appearance and assembly requirements.

[0037] This embodiment also provides a high-efficiency environmental stress screening system for sealed plate-level products, used to implement the high-efficiency environmental stress screening method for sealed plate-level products, the system comprising: The board-level products to be screened include a main PCB board 100 with a process edge 200. The process edge 200 is integrally formed with the main PCB board 100 and is provided with gold fingers 210 and mounting holes 220. Signals are brought out through the connection between the process edge 200 and the main PCB board 100. An environmental stress screening fixture 300 is provided, which includes a gold finger socket 310 with spring-loaded contacts and an aviation connector 320. One end of the gold finger socket 310 is electrically connected to the gold finger 210, and the other end of the gold finger socket 310 is connected to the testing equipment via a cable and the aviation connector 320. The environmental stress screening fixture 300 also has pre-drilled screw connection holes, which are used to fix the board-level product onto the environmental stress screening fixture 300 by connecting the screw connection holes and the mounting holes 220 with screws. A vibration table is used to perform vibration stress screening on the plate-level products to be screened, which are fixed on the environmental stress screening fixture 300. A drying chamber is used to perform temperature stress cycling on the plate-level products to be screened after vibration stress screening. A CNC depaneling machine is used to cut and remove the process edge 200 along the boundary line between the process edge 200 and the main PCB board 100 after the temperature stress cycle is completed.

[0038] Example 2 This embodiment provides an efficient environmental stress screening method for sealed plate-level products, including: Process edge 200 design: like Figure 1 As shown, process edges 200 with widths of 8mm and 21.5mm are added to both sides of the main PCB board 100 of a communication module. These process edges 200 are integrally formed with the main PCB board 100 and have the same thickness of 1.8mm. Each process edge 200 has three mounting holes 220 for screw connection and fixation with the environmental stress screening fixture 300. Two sets of gold fingers 210 are provided on each process edge 200. The gold fingers 210 include signal contacts, power contacts, and ground contacts; the gold finger 210 pads are 2mm wide, the pad spacing is 2.54mm, and the pad thickness is 30μm.

[0039] like Figure 2 As shown, a gold finger socket 310 matching the gold finger 210 is installed on the environmental stress screening fixture 300. The spring-type contacts of the gold finger socket 310 correspond one-to-one with the pads of the gold finger 210. The contact width is 2mm and the contact spacing is 2.54mm. The rear end of the gold finger socket 310 is connected to the aviation plug 320 through a wire to realize the conversion and interconnection with external testing equipment.

[0040] Environmental stress screening: The module's gold fingers 210 are mated with the gold finger socket 310, and the module is fixed to the environmental stress screening fixture 300 with screws. An external testing device is connected to the connector 320 via a cable, thus establishing an electrical connection between the module and the testing equipment. Subsequently, the environmental stress screening fixture 300 with the module mounted is fixed on a vibration test bench, and a vibration stress of 350Hz and 20g acceleration is applied to the module for 5 minutes. During the vibration screening process, key electrical signals of the module are monitored online to capture abnormal signal fluctuations.

[0041] After vibration stress screening, the module, along with the environmental stress screening fixture 300, was removed from the vibration test bench and placed in a drying oven for temperature stress cycling. The temperature range of the temperature stress cycling was -55℃ to 125℃, each cycle lasted 90 minutes, and 10 cycles were performed. During the temperature cycling process, key electrical signals of the module were monitored online to identify abnormal temperature-related signal fluctuations. The temperature stress profile of the drying oven is shown below. Figure 3 As shown.

[0042] Figure 3 The temperature cycle is divided into six time periods, T1 to T6, corresponding to processes such as heating, holding, cooling, low-temperature holding, reheating, and reheating. These are: T1 = 5 min: The heating phase from the initial temperature to the high-temperature plateau of 70°C.

[0043] T2 = 30 min: the heat preservation section of the 70℃ high-temperature platform.

[0044] T3≤13min: The cooling period from 70℃ to -55℃ low temperature platform.

[0045] T4 = 30 min: The insulation section during the stay at the -55℃ low temperature platform.

[0046] T5≤13min: The heating phase from -55℃ to the 70℃ high-temperature platform.

[0047] T6 = (60 - T3 - T5) min: the heat preservation period during which the temperature rises and falls on the 70℃ high-temperature platform, and this period is automatically compensated for according to the actual temperature rise and fall time of T3 and T5.

[0048] Board separation process: After the temperature stress cycle is completed, the process edge 200 is removed using a programmable depaneling machine. The cutting method is laser cutting, with a cutting accuracy of ±0.1mm. The cutting path is as follows: Figure 1 As shown. After cutting, the main PCB board 100 is visually inspected to confirm that it is free of defects such as cracks, delamination, chipping, and component displacement, so as to ensure that the screening and board separation process does not introduce new structural damage or assembly risks.

[0049] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, 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 technical solutions 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 method for efficient environmental stress screening of sealed plate-level products, characterized in that, include: At least one process edge (200) integrally formed with the main PCB board (100) is added to the edge of the main PCB board (100) of the product to be screened. One of the process edges (200) is provided with gold fingers (210). By routing traces at the connection between the process edge (200) and the main PCB board (100), the signals on the main PCB board (100) are introduced into the gold fingers (210) to realize electrical connection with external testing equipment. An environmental stress screening fixture (300) is provided, which is equipped with a gold finger socket (310) with spring-loaded contacts and an air connector (320). The plate-level product to be screened is fixed to the environmental stress screening fixture (300). At the same time, one end of the gold finger socket (310) is connected to the gold finger (210) to achieve electrical connection. The other end of the gold finger socket (310) is connected to the test equipment through a cable and the air connector (320). The environmental stress screening fixture (300) with the plate-level product to be screened is installed on the vibration test bench; Vibration stress screening is performed on the board-level products to be screened using the external testing equipment. In response to the completion of vibration stress screening, the environmental stress screening fixture (300) of the plate-level product to be screened is removed and placed in a drying oven to perform temperature stress cycling. In response to the completion of the temperature stress cycle, a CNC depaneling machine is used to cut along the boundary line between the process edge (200) and the main PCB board (100) to remove the process edge (200).

2. The method for efficient environmental stress screening of sealed plate-level products according to claim 1, characterized in that, The process edge (200) has the same thickness as the main PCB board (100).

3. The efficient environmental stress screening method for sealed plate-level products according to claim 1, characterized in that, The process edge (200) has two sides, which are respectively located on the two opposite edges of the main PCB board (100).

4. The efficient environmental stress screening method for sealed plate-level products according to claim 1, characterized in that, The environmental stress screening fixture (300) has reserved screw connection holes, and each of the process edges (200) is provided with mounting holes (220). The screw connection holes and the mounting holes (220) are connected by screws to fix the plate-level product onto the environmental stress screening fixture (300).

5. The efficient environmental stress screening method for sealed plate-level products according to claim 1, characterized in that, When performing vibration stress screening on the vibration table, abnormal vibration signal fluctuations are monitored during the screening process.

6. The method for efficient environmental stress screening of sealed plate-level products according to claim 1, characterized in that, The vibration conditions for the vibration stress screening include a frequency of 350 Hz, an acceleration of 20 g, and a duration of 5 min.

7. The method for efficient environmental stress screening of sealed plate-level products according to claim 1, characterized in that, When performing temperature stress cycling in the drying oven, abnormal temperature signal fluctuations are monitored during the screening process.

8. The efficient environmental stress screening method for sealed plate-level products according to claim 1, characterized in that, The temperature range of the temperature stress cycle is -55℃ to 125℃, each cycle is 90 minutes, and the cycle is 10 rounds.

9. The efficient environmental stress screening method for sealed plate-level products according to claim 1, characterized in that, The cutting accuracy of the CNC PCB splitter is ±0.1mm.

10. A high-efficiency environmental stress screening system for sealed plate-level products, characterized in that, The system for implementing the efficient environmental stress screening method for sealed plate-level products according to any one of claims 1-9 includes: The board-level products to be screened include a main PCB board (100) with a process edge (200) on the edge. The process edge (200) is integrally formed with the main PCB board (100) and is provided with gold fingers (210) and mounting holes (220). Signals are brought out through the connection between the process edge (200) and the main PCB board (100). An environmental stress screening fixture (300) is provided with a gold finger socket (310) with spring-loaded contacts and an aviation connector (320). One end of the gold finger socket (310) is electrically connected to the gold finger (210), and the other end of the gold finger socket (310) is connected to the testing equipment via a cable and the aviation connector (320). The environmental stress screening fixture (300) also has reserved screw connection holes, and the board-level product is fixed on the environmental stress screening fixture (300) by connecting the screw connection holes and the mounting holes (220) with screws. A vibration table for performing vibration stress screening on the plate-level products to be screened, which are fixed on the environmental stress screening fixture (300); A drying chamber is used to perform temperature stress cycling on the plate-level products to be screened after vibration stress screening. A CNC depaneling machine is used to cut and remove the process edge (200) along the boundary line between the process edge (200) and the main PCB board (100) after the temperature stress cycle is completed.

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