FCT test point for optimizing differential wiring impedance

Abstract

The utility model relates to the technical field of PCB circuit design, and discloses an FCT test point for optimizing differential wiring impedance, which is arranged on a pair of differential signal wiring on a circuit board and comprises a solder resist window, and the solder resist window is positioned at the coupling position of the differential signal wiring. According to the utility model, the solder resist window is arranged at the coupling part of the differential signal wire, so that the copper wire part of the differential signal wire is exposed, and the exposed copper wire of the differential signal wire and the solder resist window are used as test points to carry out FCT test. Therefore, the test process is simplified, the test cost is reduced, the influence on the impedance of the differential signal wiring is remarkably reduced, and the accuracy and reliability of the test result are ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of PCB circuit design, and more specifically, to an FCT test point for optimizing the impedance of differential traces. Background Art

[0002] In the circuit board design of electronic devices, differential signal traces are a pair of conductors used to transmit two complementary signals. Differential signal transmission is widely used in various high-speed data transmission systems due to its noise suppression ability and high bandwidth characteristics. To ensure the stable and reliable performance of differential signal traces, it is particularly important to precisely control and test their impedance.

[0003] After the circuit board is produced, testing is carried out to verify the product performance. Testing is a common form of testing, mainly by contacting the test points on the circuit board with a bed of nails, applying a certain current and voltage, checking for open circuits and short circuits on the circuit board, etc., and paying attention to the physical characteristics of the circuit. Conventional test points are composed of solder mask openings and copper plating, which are completely sufficient for detecting open circuits and short circuits. However, due to the development of the industry, especially the rise of industries such as servers and automobiles, the requirements for the impedance of signal lines are also getting higher and higher.

[0004] When traditional test points are set on high-speed differential signal traces, it will cause a sudden change in impedance. The sudden change in impedance will not only affect the quality of signal transmission but may also have an adverse impact on the device performance. If no test points are added, although the problem of sudden impedance change can be avoided, it will make the later debugging process long and complex, which is not conducive to quickly discovering and solving potential fault problems. Summary of the Utility Model

[0005] In order to overcome the problem that when existing test points are set on high-speed differential signal traces, it will cause a sudden change in impedance, and the sudden change in impedance will not only affect the quality of signal transmission but may also have an adverse impact on the device performance, the utility model provides a test point for optimizing the impedance of differential traces.

[0006] The technical solution of the utility model is as follows:

[0007] An FCT test point for optimizing the impedance of differential traces is applied to a pair of differential signal traces on a circuit board, including a solder mask opening, and the solder mask opening is located at the coupling of the differential signal traces.

[0008] According to the utility model of the above solution, the width of the solder mask opening is greater than the width of the differential signal trace.

[0009] According to the utility model of the above solution, the difference between the width of the solder mask opening and the width of the differential signal trace is 1 mil.

[0010] For the present utility model according to the above solution, the length range of the solder mask opening is 0.5 - 1.0 mm.

[0011] For the present utility model according to the above solution, the length of the solder mask opening is 0.6 mm.

[0012] For the present utility model according to the above solution, it is characterized in that the solder mask opening is located at one end of the differential signal trace adjacent to the device pin on the circuit board.

[0013] For the present utility model according to the above solution, the beneficial effect is that a solder mask opening is provided at the coupling of the differential signal traces of the present utility model, so that the copper wire part of the differential signal traces is exposed. Thus, the exposed copper wire of the differential signal traces and the solder mask opening are used as test points for FCT testing. This not only simplifies the testing process and reduces the testing cost, but also significantly reduces the impact on the impedance of the differential signal traces, ensuring the accuracy and reliability of the test results. Description of the Drawings

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0015] Figure 1 It is a schematic structural diagram of the present utility model;

[0016] Figure 2 It is Figure 1 An enlarged structural diagram of part C in

[0017] In the figure, the reference numerals are as follows:

[0018] 1, circuit board; 11, differential signal trace; 12, solder mask opening; 13, device pin. Detailed Embodiments

[0019] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present utility model more clear, the following further details the present utility model in conjunction with the drawings and embodiments.

[0020] It should be noted that the terms "comprising" and "having" in the description and claims of the present utility model, as well as any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally further include unlisted steps or units, or may optionally further include other steps or units inherent to these processes, methods, products, or devices. Terms such as "arranged" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and can be the communication inside two components or the interaction relationship between two components, unless otherwise clearly defined. The directions or positions indicated by terms such as "upper", "lower", "left", "right", "front", "rear", "bottom", etc. are based on the directions or positions shown in the drawings, and are only for convenience of description and should not be construed as a limitation to the technical solution of the present application.

[0021] It should be noted that in the circuit board design of electronic devices, differential signal traces are a pair of conductors used to transmit two complementary signals. Differential signal transmission is widely used in various high-speed data transmission systems due to its noise suppression ability and high bandwidth characteristics. In order to ensure the stable and reliable performance of differential signal traces, it is particularly important to precisely control and test their impedance.

[0022] After the circuit board is produced, tests are carried out to verify the product performance. Testing is a common form of test, mainly involving the contact between the bed of nails and the test points on the circuit board, applying a certain current and voltage, checking for open circuits and short circuits on the circuit board, etc., and paying attention to the physical characteristics of the circuit. Conventional test points are composed of solder mask openings and copper pours, which are completely sufficient for detecting open circuits and short circuits. However, due to the development of the industry, especially the rise of industries such as servers and automobiles, the requirements for the impedance of signal lines are also getting higher and higher.

[0023] When traditional test points are set on high-speed differential signal lines, it will cause sudden changes in impedance. Sudden impedance changes will not only affect the quality of signal transmission, but may also have an adverse impact on the performance of the device. If no test points are added, although the problem of sudden impedance changes can be avoided, it will make the later debugging process long and complex, which is not conducive to quickly discovering and solving potential fault problems.

[0024] Such as Figure 1 - Figure 2As shown in the figure, this embodiment provides an FCT test point for optimizing the impedance of differential traces. A solder mask opening 12 is provided at the coupling of the differential signal traces 11, so that the copper wire part of the differential signal traces 11 is exposed. Thus, the exposed copper wire of the differential signal traces 11 and the solder mask opening 12 are used as test points for FCT testing. This not only simplifies the testing process and reduces the testing cost, but also significantly reduces the impact on the impedance of the differential signal traces 11, ensuring the accuracy and reliability of the test results.

[0025] Specifically, the FCT test point for optimizing the impedance of differential traces is applied to a pair of differential signal traces 11 on the circuit board 1, including a solder mask opening 12, and the solder mask opening 12 is located at the coupling of the differential signal traces 11. Without adding additional test points, the differential signal traces 11 on the circuit board 1 are directly used for the functional test of the FCT tester, reducing the impact on impedance.

[0026] In one embodiment, the width of the solder mask opening 12 is greater than the width of the differential signal traces 11, so that the copper wire part of the differential signal traces 11 is exposed for FCT testing. When the width of the solder mask opening 12 is greater than the width of the differential signal traces 11, the test probe can more easily contact the copper wire, reducing the test errors caused by poor contact or misalignment, and helping to improve the accuracy and reliability of the test.

[0027] Preferably, during the production process of the circuit board 1, there may be a certain line width adjustment error. The difference between the width of the solder mask opening 12 and the width of the differential signal traces 11 is 1 mil, providing a certain tolerance range for the line width adjustment error. In the case of adjusting the line width in the factory or having FCT errors, the test point can still accurately and reliably contact the differential signal traces 11.

[0028] The appropriate width design of the solder mask opening 12 ensures that it will not have a significant impact on the impedance of the differential signal traces 11 during the test process. A larger area of the solder mask opening 12 can reduce the additional impedance introduced by the test point.

[0029] In one embodiment, the solder mask opening 12 is an area on the circuit board 1 for exposing the differential signal traces 11 for functional circuit testing (FCT).

[0030] First of all, the length of the solder mask opening 12 should not be too long. If the length of the solder mask opening 12 is too long, the exposed copper wire part is more likely to be affected by oxygen and other pollutants in the environment, resulting in oxidation. Oxidation will not only affect the electrical performance of the circuit board 1, but may also reduce its mechanical strength, thus shortening the service life of the circuit board 1. Therefore, when designing the length of the solder mask opening 12, it is necessary to balance the test requirements and the service life of the circuit board 1.

[0031] On the other hand, the length of the solder resist opening 12 should not be too short. If the length of the solder resist opening 12 is too short, the test probe may not be able to accurately and stably contact the copper wire, thereby affecting the detection effect of FCT. Too short solder resist opening 12 may also increase the difficulty and cost of testing because more precise testing equipment and operating skills are required.

[0032] Based on the above considerations, the length range of the solder resist opening 12 is set between 0.5 mm and 1.0 mm. This range can ensure that the test probe can stably contact the copper wire and reduce the risk of copper wire oxidation.

[0033] Preferably, the length of the solder resist opening 12 is in the range of 0.6 mm. A length of 0.6 mm can provide sufficient test stability and reliability in most applications while reducing the risk of copper wire oxidation. In practical applications, it is best to adjust and optimize according to the specific test environment and requirements.

[0034] In one embodiment, the location selection of the solder mask opening 12 is critical, especially when it comes to the differential signal trace 11. The differential signal trace 11 is a key signal transmission path on the circuit board 1, and its performance directly affects the signal quality and stability of the entire circuit board 1. In order to optimize the testing and maintenance of the differential signal trace 11, the solder mask opening 12 is usually designed at one end of the differential signal trace 11 adjacent to the device pin 13 on the circuit board 1.

[0035] The solder resist window 12 is located at one end of the differential signal trace 11 adjacent to the device pin 13 on the circuit board 1, which helps to directly and accurately contact the differential signal trace 11 during functional circuit testing (FCT), thereby obtaining accurate test data.

[0036] By precisely controlling the size and position of the solder mask opening 12, the impact on the differential trace impedance can be minimized, thereby ensuring the accuracy of the test results.

[0037] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the claims attached to the utility model.

[0038] The above is an exemplary description of the utility model patent in conjunction with the accompanying drawings. It is obvious that the implementation of the utility model patent is not limited to the above-mentioned method. As long as various improvements are made by adopting the method concept and technical solution of the utility model patent, or the concept and technical solution of the utility model patent are directly applied to other occasions without improvement, they are all within the protection scope of the utility model.

Claims

1. An FCT test point for optimizing differential trace impedance, characterized in that, Applied to a pair of differential signal traces on a circuit board, including a solder mask opening, the solder mask opening is located at the coupling of the differential signal traces, and the length range of the solder mask opening is 0.5 - 1.0 mm.

2. An FCT test point for optimizing differential trace impedance according to claim 1, characterized in that The width of the solder mask opening is greater than the width of the differential signal trace.

3. An FCT test point for optimizing differential trace impedance according to claim 2, characterized in that The difference between the width of the solder mask opening and the width of the differential signal trace is 1 mil.

4. An FCT test point for optimizing differential trace impedance according to claim 1, characterized in that, The length range of the solder mask opening is 0.6 mm.

5. An FCT test point for optimizing differential trace impedance according to claim 1, 2, 3 or 4, characterized in that The solder mask opening is located at one end of the differential signal trace adjacent to the device pin on the circuit board.

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