A test method and device for improving FPC test yield from process and procedure

Abstract

The present application is suitable for the field of flexible printed circuit board testing, and provides a test method and device for improving FPC test yield from process and technology. The method comprises: measuring the size parameters of the flexible board in advance, determining the positioning size and tolerance of the first needle mold; placing the flexible board on the first needle mold, and positioning in X and Y directions; taking the contact surface of the first needle mold and the second needle mold as the size chain reference surface in the Z-axis direction, so that the relative distance between the tip of the long probe and the test point of the flexible board forms a closed loop; the bottom surface of the first needle mold is in contact with the top surface of the second needle mold, and at the same time the long probe touches the test point of the flexible board; the circuit is turned on, and the test is completed. The positioning of the product is carried out on the flexible board shape and B2B shape, the test yield is improved from the production process, the processing reference is changed from the processing technology, the size chain is shortened, the tolerance of the closed loop is reduced, and the test yield is improved.

Description

Technical Field

[0001] This invention belongs to the field of flexible printed circuit board testing, and in particular relates to a testing method and apparatus for improving FPC testing yield from the perspective of process and technology. Background Technology

[0002] Flexible printed circuit boards (FPCs) are bendable and foldable circuit boards made of flexible insulating materials. They feature high-density wiring, thinness, and bend resistance, and are widely used in electronic products. As the performance of consumer electronics continues to improve, FPCs, acting as bridges between two rigid boards, require increasingly dense wiring. FPCs utilize multilayer board technology and high-density B2B connectors, significantly increasing the number of ICT test points. While the high-density B2B connectors have significantly smaller pin widths and spacing compared to conventional B2B connectors, the required product yield rates are becoming increasingly stringent.

[0003] Conventional test probe modules require more precise and accurate positioning of the product to ensure that the probes can penetrate the designated positions without deviation, which could lead to open circuits in the test. The probes also need to penetrate the designated area with an accurate and appropriate protrusion to ensure that the test resistance is not too high; both open circuits and excessive resistance will result in test failure. Therefore, it is evident that existing FPC testing methods suffer from insufficient test yield. Summary of the Invention

[0004] The purpose of this invention is to provide a testing method that improves FPC testing yield from the perspective of process and technology, aiming to solve the problem of insufficient testing yield in existing FPC testing.

[0005] This invention is implemented as follows: a testing method for improving FPC testing yield from the perspective of process and technology, the testing method for improving FPC testing yield from the perspective of process and technology includes the following steps:

[0006] Pre-measure the dimensional parameters of the flexible plate to determine the positioning dimensions and tolerances of the first needle die;

[0007] The flexible plate is placed on the first needle mold for positioning in the X and Y directions;

[0008] A second needle mold is floating below the first needle mold, and a third needle mold is connected to the second needle mold through a support column. A long probe is provided on the third needle mold. The contact surface between the first needle mold and the second needle mold is used as the dimensional chain reference plane in the Z-axis direction, so that the relative distance between the tip of the long probe and the test point of the flexible plate forms a closed loop.

[0009] The driving device drives the bottom surface of the first needle mold to contact the top surface of the second needle mold, while the long probe touches the test point of the flexible plate.

[0010] Connect the circuit to complete the test.

[0011] Furthermore, the pre-measurement of the dimensional parameters of the flexible plate to determine the positioning dimensions and tolerances of the first needle mold specifically includes:

[0012] Randomly select several flexible boards, measure the actual dimensions of the shape and B2B shape of each flexible board, and obtain the dimensional parameters;

[0013] By analyzing the CPK, tolerance range, and offset of the flexible plate using the aforementioned dimensional parameters, the positioning dimensions and tolerances of the first needle mold are determined.

[0014] Several flexible plates are obtained in batches from the production line, and data measurement and PPK analysis are performed. The positioning dimensions of the first needle mold are corrected based on the variation of the shape parameters.

[0015] Furthermore, the support column is connected to the second needle mold via the first support surface, and to the third needle mold via the second support surface;

[0016] Taking the contact surface of the first and second needle molds as the reference plane for the dimensional chain in the Z-axis direction, the constituent loops of the dimensional chain are: the relative distance between the flexible plate test point and the bottom surface of the first needle mold, the relative distance between the top surface of the second needle mold and the first support surface, the relative distance between the first support surface and the second support surface, the relative distance between the second support surface and the top surface of the third needle mold, the relative distance between the top surface of the third needle mold and the mounting position of the long probe, and the relative distance between the mounting position of the long probe and the tip of the long probe; the closing loop is: the relative distance between the tip of the long probe and the flexible plate test point.

[0017] Furthermore, during workpiece machining, the bottom surface of the first needle die, the top surface of the second needle die, and the top surface of the third needle die are used as machining reference surfaces.

[0018] Another objective of this invention is a testing apparatus for improving FPC testing yield, the testing apparatus comprising:

[0019] The first needle mold has a station for placing the flexible plate;

[0020] The second needle mold is floatingly connected to the first needle mold;

[0021] Support column;

[0022] The third needle mold is connected to the second needle mold via the support column;

[0023] A long probe is mounted on the third needle mold and extends to the first needle mold for testing B2B points on the flexible plate. The contact surface between the first and second needle molds is used as the dimensional chain reference plane in the Z-axis direction, so that the relative distance between the tip of the long probe and the test point on the flexible plate forms a closed loop.

[0024] Furthermore, the testing apparatus for improving FPC test yield also includes:

[0025] Fourth needle mold;

[0026] The fifth needle mold is fixedly connected to the fourth needle mold and also fixedly connected to the second needle mold; a needle sleeve is provided between the fifth needle mold and the fourth needle mold;

[0027] A single-headed probe, mounted on the needle sleeve, is used to test the HOTBAR point on the flexible plate.

[0028] Furthermore, the support column is connected to the second needle mold via the first support surface, and to the third needle mold via the second support surface;

[0029] Taking the contact surface of the first and second needle molds as the reference plane for the dimensional chain in the Z-axis direction, the constituent loops of the dimensional chain are: the relative distance between the flexible plate test point and the bottom surface of the first needle mold, the relative distance between the top surface of the second needle mold and the first support surface, the relative distance between the first support surface and the second support surface, the relative distance between the second support surface and the top surface of the third needle mold, the relative distance between the top surface of the third needle mold and the mounting position of the long probe, and the relative distance between the mounting position of the long probe and the tip of the long probe; the closing loop is: the relative distance between the tip of the long probe and the flexible plate test point.

[0030] Furthermore, during workpiece machining, the bottom surface of the first needle die, the top surface of the second needle die, and the top surface of the third needle die are used as machining reference surfaces.

[0031] Furthermore, the needle mold has four positioning dimensions, namely the positioning dimensions in the X and Y directions of the B2B point, and the positioning dimensions in the X and Y directions of the HOTBAR point.

[0032] Furthermore, a PCB board is provided at the bottom of the third needle mold.

[0033] This invention provides a testing method to improve FPC testing yield from the perspectives of process and technology. A first die positions the product in terms of both the flexible board shape and the B2B shape, thus improving testing yield from the production process perspective. Furthermore, by changing the processing benchmark in the manufacturing process, the dimensional chain is shortened, and the closed-loop tolerance is reduced, thereby improving testing yield. This embodiment has been verified through mass production and can significantly improve the testing yield of this type of product, maintaining this improvement over a long period. This improvement method also has certain reference value for the positioning design of different types of products. Attached Figure Description

[0034] Figure 1 An exploded view of the testing apparatus for improving FPC testing yield provided in an embodiment of the present invention;

[0035] Figure 2 A perspective view of a testing apparatus for improving FPC testing yield provided in an embodiment of the present invention;

[0036] Figure 3 This is a three-dimensional view of the needle output dimension chain analysis provided in an embodiment of the present invention;

[0037] Figure 4 An exploded view of the needle output dimension chain analysis provided in an embodiment of the present invention;

[0038] Figure 5 Measurement view of a flexible plate provided in an embodiment of the present invention;

[0039] Figure 6 A positioning view of the first needle mold provided in an embodiment of the present invention;

[0040] Figure label:

[0041] 1. First needle mold; 2. Second needle mold; 3. Support column; 4. Third needle mold; 5. Long probe; 6. Fourth needle mold; 7. Fifth needle mold; 8. Single-headed probe; 9. Spring; 10. Limiting copper sleeve; 11. Guide pin; 12. Linear bearing; 13. Positioning pin; 14. PCB board; 15. Needle sleeve; 16. Flexible board;

[0042] A1. Flexible plate test point; A2. Bottom surface of the first needle mold; A3. Top surface of the second needle mold; A4. First support surface; A5. Second support surface; A6. Top surface of the third needle mold; A7. Installation position of the long probe; A8. Tip of the long probe. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0044] It is understood that the terms “first,” “second,” etc., used in this application may be used herein to describe various elements, but unless otherwise stated, these elements are not limited by these terms. These terms are used only to distinguish one element from another.

[0045] like Figure 1-6 As shown, in one embodiment, a testing method for improving FPC test yield from the perspective of process and technology is proposed. The testing method for improving FPC test yield from the perspective of process and technology includes the following steps S102~S110:

[0046] Step S102: Pre-measure the dimensional parameters of the flexible plate 16 to determine the positioning dimensions and tolerances of the first needle mold 1.

[0047] Step S102 specifically includes steps S202~S206:

[0048] Step S202: Randomly select several flexible boards, measure the actual dimensions of the shape and B2B shape of each flexible board, and obtain the dimensional parameters;

[0049] Step S204: Analyze the CPK, tolerance range, and offset of the flexible plate 16 using the dimensional parameters to determine the positioning dimensions and tolerances of the first needle mold 1, such as... Figure 5 As shown;

[0050] Step S206: Obtain several flexible plates from the production line in batches, perform data measurement and PPK analysis, and correct the positioning dimensions of the first needle mold 1 based on the variation of the shape parameters, such as... Figure 6 As shown.

[0051] The flexible PCB 16, acting as a bridge between two rigid PCBs, exhibits increased wiring density as electronic product performance improves. It utilizes multilayer PCB technology and high-density B2B connectors. Compared to conventional B2B connectors, high-density B2B connectors have a similar overall size but significantly higher wiring density, resulting in a substantial reduction in pin width and pin spacing. ICT testing of B2B connectors typically involves using a probe module to position the flexible PCB and B2B, followed by probes in a probe module that strike designated areas on the B2B with a specified pin extension. To achieve high-yield testing of high-density B2B connectors and other test points on the flexible PCB, accurate and effective positioning of the flexible PCB and B2B is crucial, as is ensuring the probes strike the designated points with the appropriate pin extension. Determining the appropriate positioning gap, tolerance settings, and pin extension accuracy to meet testing requirements are key factors for achieving high-yield testing.

[0052] In this embodiment, the product needs to be tested for high-density B2B and high-density HOTBAR points on the flexible board 16. To perform high-yield testing on the B2B, the positioning gaps and tolerances in the XY directions of the B2B need to be considered to ensure that the long probe 5 can be 100% inserted into the designated pin, without any deviation causing the probe to miss and resulting in an open circuit. To perform high-yield testing on the HOTBAR, the positioning gaps and tolerances in the XY directions of the flexible board near the HOTBAR need to be considered to ensure that each single-headed probe 8 can be inserted into the designated point, avoiding open circuits caused by deviation from the insertion area; at the same time, the gaps cannot be too small to avoid interference between the flexible board 16 and the positioning points, leading to material jamming. Typically, the flexographic and B2B drawings have relatively wide tolerance ranges for their external shape, while the actual positioning tolerance range during flexible board production is relatively small. This is related to the Six Sigma management requirements of mass production and the process capabilities of the production line. When positioning flexible plates with less stringent positioning requirements, empirical dimensions are usually used to set the positioning gap and tolerance. However, for products with high requirements for positioning accuracy and yield, empirical dimensions may become ineffective.

[0053] like Figure 5 As shown, L1 is the X-direction positioning measurement dimension of B2B, L2 is the Y-direction positioning measurement dimension of B2B, L3 is the X-direction positioning measurement dimension of HOTBAR, and L4 is the Y-direction positioning measurement dimension of HOTBAR. Figure 6 As shown, D1 is the X-direction positioning dimension of B2B, D2 is the Y-direction positioning dimension of B2B, D3 is the X-direction positioning dimension of HOTBAR, and D4 is the Y-direction positioning dimension of HOTBAR.

[0054] Therefore, this embodiment adopts a design method based on actual product parameters to ensure the best positioning accuracy. A certain number of products are randomly selected from the flexible board production line, and the actual dimensions of each flexible board and the product at the B2B shape precision positioning point are measured to obtain a batch of the aforementioned dimensional parameters (L1~L4). By analyzing the product's CPK (Process Capability Index), tolerance range, and offset through the dimensional parameters, the positioning dimensions and tolerances of the first needle die 1 are determined, thereby ensuring accurate positioning accuracy. At the same time, products are selected from the production line in batches, and the PPK (Process Performance Index) of the product dimensions is measured and analyzed to analyze the variation of the shape parameters of different batches of products to correct the positioning dimensions (D1~D4) of the first needle die, which is the design for product (DFP) for the actual product, and the design parameters are improved using quality management methods.

[0055] Step S104: Place the flexible plate 16 on the first needle mold 1 for positioning in the X and Y directions.

[0056] In this embodiment, the first needle mold 1 is provided with a station for placing the flexible plate 16.

[0057] In step S106, a second needle mold 2 is floating below the first needle mold 1, and a third needle mold 4 is connected to the second needle mold 2 through a support column 3. A long probe 5 is provided on the third needle mold 4. The contact surface between the first needle mold 1 and the second needle mold 2 is taken as the dimensional chain reference surface in the Z-axis direction, so that the relative distance between the tip A8 of the long probe and the test point A1 of the flexible plate forms a closed loop.

[0058] In this embodiment, precise positioning is achieved from both process and technology perspectives, thereby improving test yield. Step S102 is implemented from the process perspective. From a technological perspective, to improve test yield, the tolerance range of the needle output must be reduced. Considering that the needle output dimension is the closed loop of the assembly dimension chain, reducing the tolerance of the closed loop can be achieved by reducing the number of component loops and reducing the range of tolerances with a large contribution rate among the component loops. Therefore, the machining datum is changed from the machining process perspective, shortening the dimension chain. Using appropriate cutting tools improves the machining accuracy of the component loops, reducing the tolerance of the closed loop and thus improving the test yield.

[0059] Specifically, such as Figure 4 As shown, the support column 3 is connected to the second needle mold 2 via the first support surface A4, and to the third needle mold 4 via the second support surface A5. Taking the contact surface between the first needle mold 1 and the second needle mold 2 as the reference surface for the dimensional chain in the Z-axis direction, the constituent loops of the dimensional chain are: the relative distance between the flexible plate test point A1 and the bottom surface A2 of the first needle mold, the relative distance between the top surface A3 of the second needle mold and the first support surface A4, the relative distance between the first support surface A4 and the second support surface A5, the relative distance between the second support surface A5 and the top surface A6 of the third needle mold, the relative distance between the top surface A6 of the third needle mold and the long probe mounting position A7, and the relative distance between the long probe mounting position A7 and the tip A8 of the long probe. The closing loop is the relative distance between the tip A8 of the long probe and the flexible plate test point A1. During workpiece machining, the bottom surface A2 of the first needle mold, the top surface A3 of the second needle mold, and the top surface A6 of the third needle mold are used as the machining reference surfaces.

[0060] Therefore, the protrusion of the long probe 5 should be appropriate and its tolerance range should be as small as possible to ensure that the spring force of the probe hitting the PIN is appropriate, avoid the phenomenon of excessive test resistance, reduce the needle mark phenomenon, and improve the test yield.

[0061] In step S108, the driving device drives the bottom surface A2 of the first needle mold to contact the top surface A3 of the second needle mold, while the long probe 5 touches the test point of the flexible plate 16.

[0062] In this embodiment, a guide pin 11 and a spring 9 are provided between the first needle mold 1 and the second needle mold 2. The guide pin 11 is inserted into a linear bearing 12, which is located inside the second needle mold 2. The first needle mold 1 and the second needle mold 2 are limited by a limiting copper sleeve 10, allowing them to float relative to each other. During operation, the pressure block is pressed onto the first needle mold 1 at a certain speed under the action of a cylinder until the first needle mold 1 and the second needle mold 2 are completely fitted together, forming the reference surface of the dimensional chain. At the same time, the long probe 5 touches the test point of the FPC.

[0063] Step S110: Connect the circuit to complete the test.

[0064] In this embodiment, when the probe product points are connected, the PCB board 14, ribbon cable, and pin sleeve 15 lead the points on the probes to the test motherboard, allowing ICT testing of the circuitry in the product. This embodiment proposes a method to improve FPC testing yield from a process and technology perspective. The first pin mold 1 positions the product in terms of flexible board shape and B2B shape, improving testing yield from the production process perspective; from the processing technology perspective, it changes the processing benchmark, shortens the dimensional chain, and reduces closed-loop tolerances, thereby improving testing yield. This embodiment has been verified through mass production and can significantly improve the testing yield of this type of product, and this improvement can be maintained for a long time. This improvement method also has certain reference value for the positioning design of different types of products.

[0065] like Figure 1-6 As shown, in one embodiment, a testing apparatus for improving FPC testing yield is proposed, the testing apparatus for improving FPC testing yield includes:

[0066] The first needle mold 1 is provided with a station for placing the flexible plate 16;

[0067] The second needle mold 2 is floatingly connected to the first needle mold 1;

[0068] Support column 3;

[0069] The third needle mold 4 is connected to the second needle mold 2 via the support column 3;

[0070] A long probe 5 is mounted on the third needle mold 4 and extends to the first needle mold 1 to test the B2B point on the flexible plate 16; the contact surface of the first needle mold 1 and the second needle mold 2 is used as the dimensional chain reference plane in the Z-axis direction, so that the relative distance between the tip A8 of the long probe and the test point A1 of the flexible plate forms a closed loop.

[0071] Fourth needle mold 6;

[0072] The fifth needle mold 7 is fixedly connected to the fourth needle mold 6 and the second needle mold 2; a needle sleeve 15 is provided between the fifth needle mold 7 and the fourth needle mold 6;

[0073] A single-headed probe 8 is mounted on the needle sleeve 15 and is used to test the HOTBAR point on the flexible plate 16.

[0074] This embodiment is the device corresponding to the above embodiments, and can realize the testing method described in the above embodiments to improve the FPC testing yield from the perspective of process and technology. In this embodiment, a spring 9 is provided between the first needle mold 1 and the second needle mold 2, and the two are connected by a limiting copper sleeve 10, so that the first needle mold 1 and the second needle mold 2 can float relative to each other within a certain position and can be reset. A guide pin 11 is provided between the first needle mold 1 and the second needle mold 2, and the guide pin 11 is inserted into a linear bearing 12. The linear bearing 12 is set in the second needle mold 2 and plays a guiding role. The second needle mold 2 and the third needle mold 4 are connected by a support column 3. A long probe 5 is installed between the third needle mold 4 and the first needle mold 1, and the third needle mold 4 restricts and fixes the ball head of the long probe. A positioning pin 13 is provided at the bottom of the third needle mold 4 for connecting and positioning the PCB board 14 at the bottom. After positioning, the two are connected by screws. The fourth needle mold 6 and the fifth needle mold 7 are connected by screws, and a needle sleeve 15 is installed between them. A single-headed probe 8 is installed on the needle sleeve 15. The fifth needle mold 7 is connected to the second needle mold 2 by pins and screws.

[0075] In this embodiment, as Figure 4 As shown, the support column 3 is connected to the second needle mold 2 via the first support surface A4, and to the third needle mold 4 via the second support surface A5. The contact surface between the first needle mold 1 and the second needle mold 2 is used as the reference surface for the dimensional chain in the Z-axis direction. The constituent loops of the dimensional chain are the relative distances between the flexible plate test point A1 and the bottom surface A2 of the first needle mold, the relative distances between the top surface A3 of the second needle mold and the first support surface A4, the relative distances between the first support surface A4 and the second support surface A5, the relative distances between the second support surface A5 and the top surface A6 of the third needle mold, the relative distances between the top surface A6 of the third needle mold and the long probe mounting position A7, and the relative distances between the long probe mounting position A7 and the tip A8 of the long probe. The closing loop is the relative distance between the tip A8 of the long probe and the flexible plate test point A1. During workpiece machining, the bottom surface A2 of the first needle mold, the top surface A3 of the second needle mold, and the top surface A6 of the third needle mold are used as the machining reference surfaces.

[0076] During testing, the flexible board 16 is placed in the positioning slot of the first pin mold 1 to position the product and B2B. The second pin mold 2 is fixed on the machine base, and the first pin mold 1 and the second pin mold 2 can float relative to each other. A pressure block is pressed onto the first pin mold 1 at a certain speed under the action of a cylinder until the first pin mold 1 and the second pin mold 2 are completely attached. At this time, the long probe 5 and the single-headed probe 8 are inserted into the designated pinning areas of B2B and HOTBAR with a specified needle output. The probes are connected to the product points, and the PCB board 14, ribbon cable, and pin sleeve 15 lead the points on the probes to the test motherboard, so that ICT testing can be performed on the circuitry in the product. After the test is completed, the pressure block is moved away from the first pin mold 1 by the cylinder, and the first pin mold 1 is moved away from the second pin mold 2 by the action of the spring 9, reaching the limit surface. At this time, the test ends.

[0077] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0078] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

[0079] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A testing method for improving FPC testing yield from the perspectives of process and technology, characterized in that, The testing method for improving FPC test yield from the perspective of process and technology includes the following steps: Pre-measure the dimensional parameters of the flexible plate to determine the positioning dimensions and tolerances of the first needle die; The flexible plate is placed on the first needle mold for positioning in the X and Y directions; A second needle mold is floating below the first needle mold, and a third needle mold is connected to the second needle mold through a support column. A long probe is provided on the third needle mold. The contact surface between the first needle mold and the second needle mold is used as the dimensional chain reference plane in the Z-axis direction, so that the relative distance between the tip of the long probe and the test point of the flexible plate forms a closed loop. The driving device drives the bottom surface of the first needle mold to contact the top surface of the second needle mold, while the long probe touches the test point of the flexible plate. Connect the circuit to complete the test; The support column is connected to the second needle mold via the first support surface, and to the third needle mold via the second support surface; Taking the contact surface of the first and second needle molds as the reference plane for the dimensional chain in the Z-axis direction, the constituent loops of the dimensional chain are: the relative distance between the flexible plate test point and the bottom surface of the first needle mold, the relative distance between the top surface of the second needle mold and the first support surface, the relative distance between the first support surface and the second support surface, the relative distance between the second support surface and the top surface of the third needle mold, the relative distance between the top surface of the third needle mold and the mounting position of the long probe, and the relative distance between the mounting position of the long probe and the tip of the long probe; the closing loop is: the relative distance between the tip of the long probe and the flexible plate test point.

2. The testing method for improving FPC testing yield from the perspective of process and technology as described in claim 1, characterized in that, The pre-measured dimensional parameters of the flexible plate are used to determine the positioning dimensions and tolerances of the first needle mold, specifically including: Randomly select several flexible boards, measure the actual dimensions of the shape and B2B shape of each flexible board, and obtain the dimensional parameters; By analyzing the CPK, tolerance range, and offset of the flexible plate using the aforementioned dimensional parameters, the positioning dimensions and tolerances of the first needle mold are determined. Several flexible plates are obtained in batches from the production line, and data measurement and PPK analysis are performed. The positioning dimensions of the first needle mold are corrected based on the variation of the shape parameters.

3. The testing method for improving FPC test yield from the perspective of process and technology as described in claim 1, characterized in that, During workpiece machining, the bottom surface of the first needle die, the top surface of the second needle die, and the top surface of the third needle die are used as machining reference surfaces.

4. A testing apparatus for improving FPC testing yield, characterized in that, The testing apparatus for improving FPC test yield includes: The first needle mold has a station for placing the flexible plate; The second needle mold is floatingly connected to the first needle mold; Support column; The third needle mold is connected to the second needle mold via the support column; A long probe is mounted on the third needle mold and extends to the first needle mold for testing B2B points on the flexible plate; the contact surface between the first and second needle molds is taken as the dimensional chain reference plane in the Z-axis direction, so that the relative distance between the tip of the long probe and the test point of the flexible plate forms a closed loop. The support column is connected to the second needle mold via the first support surface, and to the third needle mold via the second support surface; Taking the contact surface of the first and second needle molds as the reference plane for the dimensional chain in the Z-axis direction, the constituent loops of the dimensional chain are: the relative distance between the flexible plate test point and the bottom surface of the first needle mold, the relative distance between the top surface of the second needle mold and the first support surface, the relative distance between the first support surface and the second support surface, the relative distance between the second support surface and the top surface of the third needle mold, the relative distance between the top surface of the third needle mold and the mounting position of the long probe, and the relative distance between the mounting position of the long probe and the tip of the long probe; the closing loop is: the relative distance between the tip of the long probe and the flexible plate test point.

5. The testing apparatus for improving FPC testing yield according to claim 4, characterized in that, The testing apparatus for improving FPC test yield also includes: Fourth needle mold; The fifth needle mold is fixedly connected to the fourth needle mold and also fixedly connected to the second needle mold; a needle sleeve is provided between the fifth needle mold and the fourth needle mold; A single-headed probe, mounted on the needle sleeve, is used to test the HOTBAR point on the flexible plate.

6. The testing apparatus for improving FPC testing yield according to claim 4, characterized in that, During workpiece machining, the bottom surface of the first needle die, the top surface of the second needle die, and the top surface of the third needle die are used as machining reference surfaces.

7. The testing apparatus for improving FPC testing yield according to claim 5, characterized in that, The first needle mold is provided with four positioning dimensions, namely the positioning dimensions in the X and Y directions of the B2B point, and the positioning dimensions in the X and Y directions of the HOTBAR point.

8. The testing apparatus for improving FPC testing yield according to claim 4, characterized in that, The bottom of the third needle mold is provided with a PCB board.

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