Device and method for testing the powder removal performance of low-dielectric glass fiber for ultra-high frequency and high-speed PCBs

Abstract

The present invention belongs to the technical field of printed circuit boards, and specifically relates to a device and method for testing the de-powdering performance of low-dielectric glass fibers for ultra-high-frequency, high-speed PCBs. The device comprises a sample rack, on which a yarn sample is provided. A de-powdering storage box 1, a nozzle, and a de-powdering storage box 2 are sequentially provided from the sample rack to the right. De-powdering storage box 1 and de-powdering storage box 2 are connected via a nozzle, and yarn inlets and yarn outlets on the left and right ends of the nozzle are provided in de-powdering storage box 1 and de-powdering storage box 2, respectively. De-powdering storage box 1 is provided with a yarn guide roller, one end of which passes through de-powdering storage box 1 and is vertically connected to the output shaft of a linear motor. A high-speed camera is provided on the top of de-powdering storage box 2. Pressure sensors are provided at the bottoms of both de-powdering storage box 1 and de-powdering storage box 2. The device also comprises a controller, to which the pressure sensor and the high-speed camera are electrically connected. The present invention can quickly, intuitively, and accurately evaluate the de-powdering performance of yarns.

Description

Technical Field

[0001] The invention belongs to the technical field of printed circuit boards, and in particular relates to a device and a method for testing the powder removal performance of low-dielectric glass fibers used in ultra-high frequency and high-speed PCBs. Background Art

[0002] As electronic products develop towards intelligence, lightweight, high-frequency transmission, and low energy consumption, printed circuit boards (PCBs) also require their core matrix material, low-dielectric glass fiber, to have lower dielectric properties and dielectric loss, and effective adhesion to the reinforced substrate.

[0003] The current production and processing of electronic fabric, the raw material for ultra-high-frequency, high-speed PCBs, presents a significant problem of powder shedding. This is caused by friction causing the protective sizing agent on the surface of low-dielectric glass fiber yarn to fall off. This weakens the sizing's protective properties, leading to fuzzing during weaving and subsequent puncture of the copper foil, impacting PCB performance. Furthermore, because the shed sizing powder is very light, it easily floats and adheres to the glass fabric, causing poor desizing and compromising the bond between the glass fiber and the resin, leading to CAF failure in the PCB. Therefore, evaluating the powder shedding performance of low-dielectric glass fiber is crucial for the production and application of high-performance glass fiber yarns and the development of the high-end electronic information industry.

[0004] Traditional powder shedding performance testing requires measuring the amount of powder shedding during customer use, primarily through manual tracking and collection. This method suffers from long testing cycles, high sample consumption, and large errors in test results. More importantly, traditional powder shedding testing only evaluates the amount of powder shedding, without assessing the composition of the powder shedding or the surface condition of the yarn after friction. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a low-dielectric glass fiber powder removal performance testing device and testing method for ultra-high frequency and high-speed PCBs, which can quickly, intuitively and accurately evaluate the powder removal performance of yarns.

[0006] The low-dielectric glass fiber de-powdering performance testing device for ultra-high frequency and high-speed PCBs described in the present invention includes a sample rack, on which a yarn sample is provided, and a de-powdering storage box 1, a nozzle and a de-powdering storage box 2 are sequentially arranged from the starting point of the sample rack to the right; the de-powdering storage box 1 is provided with a yarn gathering port, the de-powdering storage box 2 is provided with an outlet, and the nozzle is provided with a compressed air inlet. The de-powdering storage box 1 and the de-powdering storage box 2 are connected through the nozzle, and the yarn inlet and the yarn outlet at the left and right ends of the nozzle are respectively arranged in the de-powdering storage box 1 and the de-powdering storage box 2; the de-powdering storage box 1 is provided with a parallel guide roller, the guide roller is provided with a yarn guide hole, and one end of the guide roller passes through the de-powdering storage box 1 and is vertically connected to the output shaft of the linear motor; a high-speed camera is provided on the top of the de-powdering storage box 2, and the high-speed camera shoots and records the surface state of the yarn sample passing through the de-powdering storage box 2; pressure sensors are provided at the bottoms of the de-powdering storage box 1 and the de-powdering storage box 2; and a controller is also included, and the pressure sensor and the high-speed camera are electrically connected to the controller.

[0007] Preferably, auxiliary rods are provided on the left and right sides of the yarn guide roller, and the auxiliary rods are arranged inside a de-powdering storage box. The surface of the auxiliary rods is wrapped with felt. There are 2-4 auxiliary rods. The yarn sample passes through the yarn guide hole. At the same time, the yarn samples at both ends of the yarn guide hole are against the surface of the auxiliary rod. A certain angle is always formed between the yarn guide roller and the adjacent auxiliary rods, which generates a certain tension in the yarn sample and further improves the de-powdering efficiency.

[0008] Preferably, the nozzle includes a main nozzle shell, and a core body is inserted into the main nozzle shell at one end of the main nozzle shell, which is in contact with the inner wall of the main nozzle shell; a yarn channel is provided in the middle of the core body, one end of the yarn channel is connected to the yarn inlet, and the other end of the yarn channel is connected to the yarn outlet through a tapered mouth, and a tapered rectifier chamber is formed between the outer wall of the tapered mouth and the inner wall of the main nozzle shell; an annular air storage chamber is provided on the periphery of the core, and a gas diverter valve is provided between the annular air storage chamber and the tapered mouth, and the annular air storage chamber is connected to the tapered rectifier chamber through the gas diverter valve; a compressed air inlet is provided on the main nozzle shell, and the compressed air inlet is connected to the annular air storage chamber.

[0009] Preferably, the compressed air inlet is connected to a compressed air control box, which controls the delivery and stop of compressed air. The compressed air control box is provided with a compressed air pressure controller and a compressed air time controller, which are used to adjust the compressed air pressure and the compressed air outlet time, respectively.

[0010] Preferably, the first and second powder removal storage boxes and the bottom of the nozzle are all provided with a support frame, which is a telescopic support frame.

[0011] Preferably, the inlet of the first powder removal storage box and the outlet of the second powder removal storage box are parallel and corresponding.

[0012] Preferably, the first and second powder removal storage boxes are both made of metal, more preferably stainless steel.

[0013] Preferably, the first and second powder removal storage boxes are both provided with upper covers, which facilitate the subsequent movement and handling of the powder removal.

[0014] Each yarn is made up of multiple threads. The wetting agent applied to the yarn surface also helps to gather the threads together. When the wetting agent is rubbed off, the nozzle sprays the threads, causing them to become fluffy and expand slightly, resulting in an increase in yarn width. The nozzle sprays the yarn under the action of compressed air; a high-speed camera captures the yarn surface after spraying and records the change in yarn width after friction. The smaller the width change after friction, the better the film-forming property of the wetting agent on the yarn surface, and the better the protection of the yarn. The pressure sensor automatically transmits the detected pressure signal to the controller, which is converted into a weight signal, thereby automatically measuring the weight of the de-powdered yarn.

[0015] The yarn surface images taken by the high-speed camera are transmitted to the controller, processed by the controller, and the yarn width is counted.

[0016] The method for testing the powder removal performance of low-dielectric glass fibers for ultra-high-frequency, high-speed PCBs of the present invention uses the above-mentioned device and includes the following steps:

[0017] S1. Pull out the yarn sample to be tested, enter the interior of the de-powdering storage box 1 through the yarn gathering port at the inlet of the de-powdering storage box 1, pass through the yarn guide hole on the yarn guide roller and enter the yarn inlet, pass through the nozzle and enter the de-powdering storage box 2 from the yarn outlet, and then pull out from the outlet of the de-powdering storage box 2;

[0018] S2, adjusting the height of the powder removal storage box 1, the nozzle, and the powder removal storage box 2 so that the inlet of the powder removal storage box 1, the yarn inlet of the nozzle, the yarn outlet, and the outlet of the powder removal storage box 2 are parallel to each other;

[0019] S3, the external compressed air control box is connected to the compressed air inlet through a pipeline;

[0020] S4. Clear the data, set the injection time to 30-120 minutes, the injection pressure to 3-6 MPa, the linear motor movement frequency to 500 times / min, the movement amplitude to 1-2 cm, the linear motor drives the yarn guide roller to move up and down, start the compressed air control box, and the yarn sample rubs against the edge of the yarn guide hole, the auxiliary rod, and the yarn inlet and yarn outlet of the nozzle during the injection process. When the set time is reached, the injection stops automatically;

[0021] S5. Record the yarn delivery speed V and injection time T, obtain the powder removal weight M1 through the pressure sensor, record the yarn state after injection through a high-speed camera, count the yarn width in the image, record the yarn width W, and evaluate the powder removal performance of the yarn sample.

[0022] Preferably, in step S1, 9 yarn samples are evenly arranged in 3 rows and 3 columns on the sample rack; in step S2, the first inlet of the de-powdering storage box, the nozzle yarn inlet and yarn outlet, and the second outlet of the de-powdering storage box are all arranged opposite to the yarn samples in the 2nd row and 2nd column.

[0023] Preferably, in step S5, the yarn sample powder removal performance evaluation parameters include:

[0024] N: The amount of powder removed per 10,000 meters,

[0025] N = M1 × 10000 / (V × T);

[0026] H: yarn width before spraying,

[0027] I: average yarn width after spraying,

[0028] J: average yarn width before jetting,

[0029] K: expansion degree,

[0030] I=(W1+W2+W3+..+Wn) / n,

[0031] J=(H1+H2+H3+..+Hn) / n,

[0032] K = (IJ) / J; M2: Collect all the powdered powder in the powdered powder storage box 1 and the powdered powder storage box 2, smolder at 625 ° C for 0.5 h, and record the remaining weight after smoldering as M2;

[0033] E: the proportion of inorganic components in the de-powdering process, F: the proportion of organic components in the de-powdering process,

[0034] E=M2 / M1×100%, F=100%-E.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1. The present invention can set up multiple yarn samples for simultaneous testing, avoiding the situation where too little powder removal is caused by too few yarn samples, thereby causing large errors. At the same time, it saves time and reduces errors caused by changes in the test environment.

[0037] 2. The present invention is equipped with an automatic stop system, and the nozzle spraying can be timed. When the friction time reaches the set value, it automatically stops to prevent manual timing errors;

[0038] 3. A high-speed camera is installed on the top of the second powder removal storage box to record the change in yarn width after friction and evaluate the powder removal performance of the yarn;

[0039] 4. A pressure sensor is equipped to automatically record the weight of powder removal to avoid manual weighing errors;

[0040] 5. The tension can be changed by adjusting the injection pressure, with an adjustment range of 3-6 MPa. The appropriate injection pressure can be selected according to different yarn varieties to avoid too little powder removal due to too low pressure, thereby reducing test errors. At the same time, the present invention provides a yarn guide roller, which is provided with a yarn guide hole. While the yarn passes through the yarn guide hole and is transmitted forward, the linear motor maintains a certain frequency and moves up and down, driving the yarn guide roller to move up and down, thereby increasing the friction effect. While the yarn guide roller moves up and down, the angle between the yarn guide roller and the adjacent auxiliary rod is always maintained, so that tension is formed on the yarn sample. The surface of the auxiliary rod is wrapped with felt, which further improves the powder removal efficiency.

[0041] 6. Compared with the traditional method of testing the amount of powder removed during use by customers, the powder removal storage box 1 and the powder removal storage box 2 in the present invention are both sealed devices, which prevents the powder from being scattered everywhere due to its light weight, and the amount of powder removed is large;

[0042] 7. Since static electricity is easily generated during the friction powder removal process, the powder removal storage box is made of metal materials such as stainless steel to facilitate the conduction of the charge generated by friction, avoiding the powder flying around due to static electricity and being difficult to clean. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a schematic structural diagram of a device for testing the powder removal performance of low-dielectric glass fibers for ultra-high frequency and high-speed PCBs according to the present invention;

[0044] Figure 2 This is a schematic diagram of the structure of a powder removal storage box;

[0045] Figure 3 This is a schematic diagram of the structure of the powder removal storage box II;

[0046] Figure 4 It is a schematic diagram of the nozzle structure;

[0047] Figure 5 It is the AA section view;

[0048] In the figure, 1. sample rack; 2. yarn sample; 3. powder removal storage box 1; 4. nozzle; 5. powder removal storage box 2; 6. compressed air inlet; 7. yarn guide roller; 8. high-speed camera; 9. main nozzle housing; 10. core body; 11. yarn channel; 12. conical mouth; 13. uniformly tapered rectifier chamber; 14. annular air storage chamber; 15. gas diverter valve; 16. support frame; 17. compressed air control box; 18. auxiliary rod. DETAILED DESCRIPTION

[0049] The following will be combined with the accompanying drawings and examples to clearly and completely describe the technical solution of the present invention. Figure 1-5As shown, in this embodiment, the low-dielectric glass fiber de-powdering performance testing device for ultra-high frequency and high-speed PCB includes a sample rack 1, on which a yarn sample 2 is provided, and from the sample rack 1 to the right, a de-powdering storage box 1 3, a nozzle 4 and a de-powdering storage box 2 5 are sequentially provided, and a retractable support frame 16 is provided at the bottom of the de-powdering storage box 1 3, the de-powdering storage box 2 5 and the nozzle 4; an inlet is provided on the de-powdering storage box 1 3, an outlet is provided on the de-powdering storage box 2 5, and a compressed air inlet 6 is provided on the nozzle 4, and the de-powdering storage box 1 3 and the de-powdering storage box 2 5 are connected through the nozzle 4, and the left and right ends of the nozzle 4 are The yarn inlet and yarn outlet are respectively arranged in the depowdering storage box 1 3 and the depowdering storage box 2 5; a parallel guide roller 7 is provided inside the depowdering storage box 1 3, and the guide roller 7 is provided with a yarn guide hole. One end of the guide roller 7 passes through the depowdering storage box 1 3 and is vertically connected to the output shaft of the linear motor; a high-speed camera 8 is provided on the top of the depowdering storage box 2 5, and the high-speed camera 8 shoots and records the surface state of the yarn sample 2 passing through the depowdering storage box 2 5; pressure sensors are provided at the bottom of the depowdering storage box 1 3 and the depowdering storage box 2 5; a controller is also included, and the pressure sensor and the high-speed camera 8 are electrically connected to the controller.

[0050] An auxiliary rod 18 is provided on each side of the yarn guide roller 7. The auxiliary rod 18 is arranged inside the powder removal storage box 3, and the surface of the auxiliary rod 18 is wrapped with felt.

[0051] The nozzle 4 includes a main nozzle shell 9, and a core body 10 is inserted into the main nozzle shell 9 at one end thereof, which is fitted into the inner wall of the main nozzle shell 9; a yarn channel 11 is provided in the middle of the core body 10, one end of the yarn channel 11 is connected to the yarn inlet, and the other end of the yarn channel 11 is connected to the yarn outlet through a tapered mouth 12, and a uniformly tapered rectifier chamber 13 is formed between the outer wall of the tapered mouth 12 and the inner wall of the main nozzle shell 9; an annular air storage chamber 14 is provided on the outer periphery of the core body 10, and a gas diverter valve 15 is provided between the annular air storage chamber 14 and the tapered mouth 12, and the annular air storage chamber 14 is connected to the uniformly tapered rectifier chamber 13 through the gas diverter valve 15; a compressed air inlet 6 is provided on the main nozzle shell 9, and the compressed air inlet 6 is connected to the annular air storage chamber 14.

[0052] The compressed air inlet 6 is connected to the compressed air control box 17 .

[0053] The method for testing the powder removal performance of low-dielectric glass fiber for ultra-high frequency and high-speed PCBs comprises the following steps:

[0054] S1. A total of 9 yarn samples 2 are evenly arranged in 3 rows and 3 columns on the sample rack. The yarn samples 2 to be tested are pulled out respectively, enter the interior of the de-powdering storage box 1 through the yarn gathering port of the de-powdering storage box 1 3, pass through the yarn guide hole on the yarn guide roller 7 and enter the yarn inlet. At the same time, the yarn sample 2 is pressed against the surface of the auxiliary rod 18 on both sides of the yarn guide roller 7, passes through the nozzle 4, and enters the de-powdering storage box 2 5 from the yarn outlet, and then is pulled out from the outlet of the de-powdering storage box 2 5;

[0055] S2. Adjust the height of the de-powdering storage box 1 3, the nozzle 4, and the de-powdering storage box 2 5 so that the inlet of the de-powdering storage box 1 3, the yarn inlet and yarn outlet of the nozzle 4, and the outlet of the de-powdering storage box 2 5 are all arranged opposite to the yarn sample 2 in the 2nd row and 2nd column; in this way, the yarn samples 2 that are symmetrical about the middle yarn sample 2 (i.e., the yarn sample 2 in the 2nd row and 2nd column) can form a relatively symmetrical tension.

[0056] S3, the external compressed air control box 17 is connected to the compressed air inlet 6 through a pipeline;

[0057] S4. Clear the data, set the injection time to 100 min, the injection pressure to 3 MPa, the linear motor movement frequency to 500 times / min, the movement amplitude to 1.5 cm, start the compressed air control box 17, and during the injection process, the yarn sample 2 rubs against the edge of the yarn guide hole, the auxiliary rod 18, and the yarn inlet and yarn outlet of the nozzle 4. When the set time is reached, the injection stops automatically;

[0058] S5. Record the yarn delivery speed V and the injection time T, obtain the powder removal weight M1 through the pressure sensor, record the yarn state after injection through the high-speed camera 8, count the yarn width in the picture, record the yarn width W, and evaluate the powder removal performance of the yarn sample 2.

[0059] In step S5, the evaluation parameters for the powder removal performance of the yarn sample 2 include:

[0060] N: The amount of powder removed per 10,000 meters,

[0061] N = M1 × 10000 / (V × T);

[0062] H: yarn width before spraying,

[0063] I: average yarn width after spraying,

[0064] J: average yarn width before jetting,

[0065] K: expansion degree,

[0066] I=(W1+W2+W3+..+Wn) / n,

[0067] J=(H1+H2+H3+..+Hn) / n,

[0068] K = (IJ) / J;

[0069] M2: Collect all the powder in the powder storage box 1 3 and the powder storage box 2 5, smolder at 625℃ for 0.5h, and record the remaining weight after smoldering as M2;

[0070] E: the proportion of inorganic components in the de-powdering process, F: the proportion of organic components in the de-powdering process;

[0071] E=M2 / M1×100%, F=100%-E.

[0072] Samples 1-4 were subjected to de-powdering performance tests respectively through the above steps, with a spraying time of 100 min and a spraying pressure of 3 MPa. The results are shown in Table 1.

[0073] Table 1 Powder removal performance test table of samples 1-4

[0074]

[0075]

[0076] Among them, tex represents the weight of yarn per kilometer, unit: g / km;

[0077] Glass type E indicates ordinary alkali-free glass, and T indicates high-strength and high-modulus glass;

[0078] Sizing agent type Y represents a starch-based sizing agent.

[0079] Table 2 Glass fiber yarn powder removal performance rating table

[0080]

[0081] According to Table 2, the powder removal performance test level of samples 1 and 2 is A, and the powder removal performance test level of samples 3 and 4 is C.

[0082] Through analysis, sample 1 has the smallest powder removal amount and expansion degree after friction, the highest content of de-powdered organic matter, and the best de-powdering performance.

[0083] By comparing samples 1, 2, and 3, it is shown that the finer the fiber diameter, the better the de-powdering performance.

[0084] By comparing samples 3 and 4, it is shown that the powder removal performance of ordinary alkali-free glass is better than that of yarn products made from high-strength and high-modulus glass. The reason may be that the yarn products made from high-strength and high-modulus glass are hard, brittle, not wear-resistant, and shed more powder.

[0085] The powder removal amount is detected by the method of the powder removal device, which is consistent with the on-site usage and has a good evaluation effect. The present invention provides a research direction for the development of low-dielectric glass fiber spun yarn products.

[0086] The low-dielectric glass fiber powder removal performance testing device and testing method of the embodiments of the present invention described above in conjunction with the drawings realize the powder removal performance detection and evaluation of low-dielectric glass fiber yarns, solving the problems existing in the prior art.

Claims

1. A device for testing the powder removal performance of low-dielectric glass fiber for ultra-high frequency and high-speed PCBs, characterized in that: The invention comprises a sample rack (1), a yarn sample (2) is provided on the sample rack (1), and a de-powdering storage box (3), a nozzle (4) and a de-powdering storage box (5) are provided in sequence from the sample rack (1) to the right; the de-powdering storage box (3) is provided with a yarn gathering port, the de-powdering storage box (5) is provided with an outlet, the nozzle (4) is provided with a compressed air inlet (6), the de-powdering storage box (3) and the de-powdering storage box (5) are connected through the nozzle (4), and the yarn inlet and the yarn outlet at the left and right ends of the nozzle (4) are respectively provided in the de-powdering storage box (3) and the de-powdering storage box (5); A yarn guide roller (7) is provided in parallel inside the de-powdering storage box (3), and the yarn guide roller (7) is provided with a yarn guide hole. One end of the yarn guide roller (7) passes through the de-powdering storage box (3) and is vertically connected to the output shaft of the linear motor; a high-speed camera (8) is provided on the top of the de-powdering storage box (5), and the high-speed camera (8) takes pictures and records the surface state of the yarn sample (2) passing through the de-powdering storage box (5); pressure sensors are provided at the bottoms of the de-powdering storage box (3) and the de-powdering storage box (5); and a controller is also included, and the pressure sensor and the high-speed camera (8) are both electrically connected to the controller; Auxiliary rods (18) are also provided on the left and right sides of the yarn guide roller (7), and the auxiliary rods (18) are arranged inside the powder removal storage box (3). The surface of the auxiliary rods (18) is wrapped with felt; The nozzle (4) comprises a main nozzle housing (9), one end of the main nozzle housing (9) is fitted into the inner wall of the main nozzle housing (9) and a core body (10) is inserted therein; a yarn channel (11) is provided in the middle of the core body (10), one end of the yarn channel (11) is connected to the yarn inlet, and the other end of the yarn channel (11) is connected to the yarn outlet through a tapered opening (12), and a uniformly tapered rectifying chamber (13) is formed between the outer wall of the tapered opening (12) and the inner wall of the main nozzle housing (9); an annular air storage chamber (14) is provided on the outer periphery of the core body (10), a gas diverter valve (15) is provided between the annular air storage chamber (14) and the tapered opening (12), and the annular air storage chamber (14) is connected to the uniformly tapered rectifying chamber (13) through the gas diverter valve (15); a compressed air inlet (6) is provided on the main nozzle housing (9), and the compressed air inlet (6) is connected to the annular air storage chamber (14).

2. The low dielectric glass fiber powder removal performance testing device for ultra-high frequency and high-speed PCB according to claim 1, characterized in that: The compressed air inlet (6) is connected to the compressed air control box (17).

3. The low dielectric glass fiber powder removal performance testing device for ultra-high frequency and high-speed PCB according to claim 1, characterized in that: The bottoms of the powder removal storage box 1 (3), the powder removal storage box 2 (5) and the nozzle (4) are all provided with a support frame (16).

4. The low dielectric glass fiber powder removal performance testing device for ultra-high frequency and high-speed PCB according to claim 1, characterized in that: The inlet of the powder removal storage box 1 (3) and the outlet of the powder removal storage box 2 (5) correspond in parallel.

5. A method for testing the powder removal performance of low-dielectric glass fiber for ultra-high frequency and high-speed PCBs, using the device according to any one of claims 1 to 4, characterized in that: The steps include: S1. Pull out the yarn sample (2) to be tested, enter the interior of the de-powdering storage box (3) through the yarn gathering port of the de-powdering storage box (3), pass through the yarn guide hole on the yarn guide roller (7), enter the yarn inlet, pass through the nozzle (4), and enter the de-powdering storage box (5) from the yarn outlet, and then pull out from the outlet of the de-powdering storage box (5); S2, adjusting the height of the de-powdering storage box 1 (3), the nozzle (4), and the de-powdering storage box 2 (5) so that the inlet of the de-powdering storage box 1 (3), the yarn inlet of the nozzle (4), the yarn outlet, and the outlet of the de-powdering storage box 2 (5) are parallel to each other; S3, an external compressed air control box (17) is connected to a compressed air inlet (6) via a pipeline; S4, data is cleared, the injection time is set to 30-120 min, the injection pressure is set to 3-6 MPa, the linear motor movement frequency is set to 500 times / min, the movement amplitude is set to 1-2 cm, the linear motor drives the yarn guide roller (7) to move up and down, and the compressed air control box (17) is started. During the injection process, the yarn sample (2) rubs against the edge of the yarn guide hole, the auxiliary rod (18), the yarn inlet and the yarn outlet of the nozzle (4). When the set time is reached, the injection stops automatically; S5, record the yarn delivery speed V, the injection time T, obtain the powder removal weight M1 through the pressure sensor, record the yarn state after injection through the high-speed camera (8), count the yarn width in the picture, record the yarn width W, and evaluate the powder removal performance of the yarn sample (2).

6. The method for testing the powder removal performance of low dielectric glass fiber for ultra-high frequency and high-speed PCB according to claim 5, characterized in that: In step S1, 9 yarn samples (2) are evenly arranged in 3 rows and 3 columns on the sample rack (1); in step S2, the inlet of the first de-powdering storage box (3), the yarn inlet and yarn outlet of the nozzle (4), and the outlet of the second de-powdering storage box (5) are all arranged opposite to the yarn sample (2) in the second row and the second column.

7. The method for testing the powder removal performance of low dielectric glass fiber for ultra-high frequency and high-speed PCB according to claim 5, characterized in that: In step S5, the evaluation parameters of the powder removal performance of the yarn sample (2) include: N: The amount of powder removed per 10,000 meters, N=M1×10000 / (V×T); H: yarn width before spraying, I: average yarn width after spraying, J: average yarn width before jetting, K: expansion degree, I=(W1+W2+W3+..+Wn) / n, J=(H1+H2+H3+..+Hn) / n, K = (IJ) / J; M2: Collect all the powdered powder in the powdered powder storage box 1 (3) and the powdered powder storage box 2 (5), and smolder them at 625℃ for 0.5h. The remaining weight after smoldering is recorded as M2; E: the proportion of inorganic components in the de-powdering process, F: the proportion of organic components in the de-powdering process, E=M2 / M1×100%, F=100%-E.

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