A control method for circuit board (CAF) failure

Abstract

The application discloses a control method for CAF failure of a circuit board, and the control method is as follows: S1, the fiberglass looseness and fiberglass hollow of an insulating cloth layer are detected through a microscope, wherein the cloth layer with fiberglass hollow greater than 30ppm is rejected; S2, the line width compensation of a copper foil is increased, and the etching rate of the copper foil is improved, so that copper teeth are avoided on the copper foil; S3, the circuit board is drilled through drilling equipment; S4, defects of the circuit board are monitored through image detection, and the circuit board is repaired; and S5, the circuit board is detected under the environment of 85 DEG C / 85%RH, and good circuit boards without CAF failure are selected. The application comprehensively considers three factors of material, process and environment, constructs a multi-dimensional control model, effectively inhibits the possibility of CAF failure of the circuit board, reduces economic losses caused by CAF failure, and improves long-term reliability of the circuit board.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of CAF failure control, and particularly relates to a control method for CAF failure of a circuit board. BACKGROUND

[0002] Conductive anodic filament (CAF) is a leakage phenomenon of printed circuit board (PCB) under the driving of voltage and in a humid environment, which is caused by the migration of conductive ions along the channel of glass fiber cracks, hollows and the like due to material defects or process problems. CAF failure can seriously reduce the long-term reliability of the circuit board, especially in high temperature and high humidity scenes.

[0003] The existing CAF test method is usually based on the electrical performance detection of finished boards, and whether failure occurs is judged by applying voltage and monitoring leakage current. For example, patent 2024116743258 proposes a test method for a printed circuit board CAF test module, but does not involve material selection and process optimization in the process.

[0004] The existing CAF test method does not combine the key control points in the process of the circuit board, so that the test result cannot guide the process optimization, and still causes great economic loss, and the probability of poor quality circuit board passing the CAF test is large, which affects the long-term reliability of the circuit board.

[0005] Therefore, it is necessary to propose a control method for CAF failure of a circuit board to avoid CAF failure from multiple angles, which is an important technical problem to be solved. SUMMARY

[0006] The present application provides a control method for CAF failure of a circuit board, which aims to solve the problem that the existing CAF test method does not combine the key control points in the process of the circuit board, so that the test result cannot guide the process optimization, still causes great economic loss, and the probability of poor quality circuit board passing the CAF test is large, which affects the long-term reliability of the circuit board.

[0007] To achieve the above-mentioned purpose, the present application provides a control method for CAF failure of a circuit board, and the control method is as follows: S1, detecting the glass fiber looseness and glass fiber hollow of the insulating cloth layer by a microscope, wherein the cloth layer with glass fiber hollow > 30ppm is rejected; S2, increasing the line width compensation of the copper foil and improving the etching rate of the copper foil to avoid the generation of copper teeth on the copper foil; S3, drilling the circuit board by a drilling equipment; S4, monitoring the defects of the circuit board by image detection and repairing; S5, detecting the circuit board in a 85℃ / 85%RH environment, and selecting good circuit boards without CAF failure.

[0008] In some embodiments, the S3 comprises the following steps: S31, inputting the positions of the holes of the circuit board into the drilling device; S32, determining a basic drilling position, the drilling device first forms the basic drilling position; S33, obtaining the distance D between the hole adjacent to the basic drilling position and the basic drilling position, when D is greater than or equal to 7.5mm, the drilling device forms the hole adjacent to the basic drilling position; when D is less than 7.5mm, the hole adjacent to the basic drilling position is ignored, the distance D between the hole next to the basic drilling position and the basic drilling position is obtained, and the above comparison step is repeated; S34, taking the just-formed hole as a new basic drilling position, and repeating step S33.

[0009] In some embodiments, the S32 specifically comprises the following steps: the rotating speed of the drill bit of the drilling device is 30000-36000rpm.

[0010] In some embodiments, the drilling device comprises: a rack; a drilling platform movably arranged on the rack; a transverse carriage movably arranged on the rack; a drill table movably arranged on the transverse carriage, and the drill bit is rotatably arranged on the drill table; a drill bit drive arranged on the drill table and connected to the drill bit; a limiting member installed on the drilling platform, and a limiting cavity is arranged in the limiting member, and the circuit board is located in the limiting cavity; and a pressing member arranged on the limiting member and abutting against the circuit board.

[0011] In some embodiments, it further comprises: a bottom pad layer located at the bottom of the limiting cavity, and the circuit board is located in the limiting cavity and above the bottom pad layer; an aluminum plate layer arranged in the limiting cavity and above the circuit board, and the aluminum plate layer is provided with a through hole matched with the hole of the circuit board.

[0012] In some embodiments, it further comprises: a cutting fluid, the through hole stores the cutting fluid; a plugging layer arranged at the bottom of the through hole; and an aluminum film layer arranged in the limiting cavity and above the aluminum plate layer.

[0013] In some embodiments, it further comprises: a longitudinal movement drive arranged on the rack and connected to the drilling platform; a transverse movement drive arranged on the rack and connected to the transverse carriage; and a vertical movement drive arranged on the transverse carriage and connected to the drill table.

[0014] In some embodiments, the image detection method in the S4 specifically comprises the following steps: full inspection of the circuit board is performed through ccd detection, and whether the circuit board has scratches and impurities is judged.

[0015] In some embodiments, the circuit board detection method in the S5 specifically comprises the following steps: a rated voltage is applied to the circuit board, the ion migration current in the insulating layer of the circuit board is monitored in real time through a high-precision conductivity meter, and the test is continuously performed for 500 hours.

[0016] In some embodiments, the circuit board detection method in S5 is as follows: a rated voltage is applied to the circuit board, and the temperature rise of each region of the circuit board is detected by an infrared imager, and the test is continued for 500 hours.

[0017] The technical scheme of the present application proposes a control method for CAF failure of a circuit board, and the control method is as follows: S1, the looseness of glass fiber and the hollow of glass fiber of an insulating cloth layer are detected by a microscope, and the cloth layer with a hollow of glass fiber > 30ppm is rejected; S2, the line width compensation of copper foil is increased, and the etching rate of copper foil is improved to avoid the generation of copper teeth on the copper foil; S3, the circuit board is drilled by a drilling device; S4, the defects of the circuit board are monitored by image detection and repaired; and S5, the circuit board is detected in an environment of 85℃ / 85%RH to select good circuit boards without CAF failure. The present application selects a high-quality insulating cloth layer with compact glass fiber and a hollow of glass fiber ≤ 30ppm as a raw material of the insulating cloth layer of the circuit board in the material preparation stage, so as to inhibit the possibility of CAF failure of the circuit board from the beginning of the raw material selection stage. The present application increases the line width compensation of copper foil, increases the etching rate, optimizes the parameters of drilling, and performs image full detection on the circuit board, so as to inhibit the possibility of CAF failure of the circuit board in multiple aspects in the process stage. The present application performs CAF failure monitoring in a high-temperature and high-humidity environment, induces CAF failure of poor circuit boards, removes the poor circuit boards, and retains good circuit boards, so as to realize the control of CAF failure of the circuit board. Through the above steps, the present application comprehensively considers three factors of material, process, and environment, constructs a multi-dimensional control model, effectively inhibits the possibility of CAF failure of the circuit board, reduces economic losses caused by CAF failure, and improves the long-term reliability of the circuit board. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor based on these drawings.

[0019] Figure 1 The technical roadmap of the control method for CAF failure of the circuit board in an embodiment of the present application;

[0020] Figure 2 The structural schematic diagram of the circuit board in an embodiment of the present application;

[0021] Figure 3 The top view of the circuit board in an embodiment of the present application;

[0022] Figure 4 It is a perspective view of the drilling device in an embodiment of the present application;

[0023] Figure 5 It is a sectional view of the drilling device in an embodiment of the present application;

[0024] Figure 6 It is Figure 5 It is a partial enlarged view of A part in the middle.

[0025] In the figure: circuit board 1, copper foil layer 101, epoxy resin layer 102, insulating cloth layer 103, connecting hole 104, longitudinal displacement drive 2, transverse displacement frame 3, drill bit drive 4, vertical displacement drive 5, transverse displacement drive 6, drill bit 7, pressing member 8, limiting member 9, drilling platform 10, guide rail frame 11, bearing seat 12, bearing 13, guide rail 14, rack 15, aluminum film layer 16, aluminum plate layer 17, plugging layer 18, bottom pad layer 19. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0027] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present application are only used to explain the relative positional relationship, movement condition, etc. between components in a certain posture (as shown in the drawings), and if the certain posture changes, the directional indications also change accordingly.

[0028] It should also be noted that when an element is referred to as being “fixed to” or “set on” another element, it can be directly on the other element or there can be a middle element. When an element is referred to as being “connected” to another element, it can be directly connected to the other element or there can be a middle element.

[0029] In addition, the description of “first”, “second” and the like in the present application is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined as “first” and “second” can explicitly or implicitly include at least one of the features. In addition, the technical solutions of various embodiments can be combined with each other, but it must be based on the fact that a person skilled in the art can realize it, and when the combination of technical solutions appears to be contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the scope of protection claimed by the present application.

[0030] Referring to Figure 1 and Figure 2 As shown in the figure, the present application proposes a control method for CAF failure of a circuit board 1, the circuit board 1 comprises a copper foil layer 101 and an insulating layer, the insulating layer is arranged between two adjacent copper foil layers 101, the insulating layer comprises an insulating cloth layer 103 and an epoxy resin layer 102 arranged on both sides of the insulating cloth layer 103, in order to realize the electrical connection between the two adjacent copper foil layers 101, a connecting hole 104 is arranged between the two copper foil layers 101, and copper is deposited by electroplating to realize the connection between the two adjacent copper foil layers 101, the process of the circuit board 1 comprises: preparation, pressing, circuit, drilling, copper electroplating, solder mask, text, shape, surface treatment, inspection, packaging, the circuit is formed by etching, the present application combines the process of the circuit board 1 and CAF detection to comprehensively control the CAF failure of the circuit board 1, and the control method is as follows:

[0031] S1, detect the glass fiber looseness and glass fiber hollow of the insulating cloth layer 103 by a microscope, wherein the cloth layer with glass fiber hollow > 30ppm is rejected; in the present application, the insulating cloth layer 103 selects glass fiber cloth, preferably flat yarn or laser cloth, the glass fiber looseness is detected by an optical microscope, the more loose the glass fiber is, the more likely the CAF failure is to occur, the glass fiber cloth layer with compact glass fiber is selected as the raw material of the insulating cloth layer 103, which is beneficial to reduce the possibility of CAF failure of the circuit board 1; and the glass fiber hollow will greatly induce the CAF failure of the circuit board 1, the glass fiber hollow is detected by an electron microscope or an optical microscope, and the glass fiber hollow is ≤ 30ppm.

[0032] S2, increase the line width compensation of the copper foil and improve the etching rate of the copper foil to avoid the formation of copper teeth on the copper foil; the copper foil is preferably RTF copper foil, during the process of etching to form the circuit, copper teeth may be formed on the copper foil due to incomplete etching, the line width compensation is increased as much as possible under the premise of not affecting the resolution of the exposure machine and the line width, and the etching rate is increased, the increase of the etching rate is beneficial to avoid the formation of copper teeth on the copper foil, the large line width compensation can ensure the reliability of the circuit under the condition of large etching rate, the copper teeth are easy to induce the CAF failure of the circuit board 1, and the occurrence of the copper teeth can well control the CAF failure of the circuit board 1;

[0033] S3, drill the circuit board 1 by a drilling equipment; the highest temperature generated during the drilling process of the existing drilling equipment is about 200℃, which has exceeded the TG point of the material, and will damage the resin material in the insulating layer and the insulating cloth layer 103 material, in the present application, low speed (50% to 60% of the conventional speed), low down speed and jump drilling are adopted to avoid damage to the resin material in the insulating layer and the insulating cloth layer 103 material during drilling, so as to achieve the purpose of controlling the CAF failure of the circuit board 1.

[0034] S4, monitor the defects of the circuit board 1 through image detection, and repair; the image detection is realized through CCD detection or AOI full detection, defects on the circuit board 1 are detected, the defects include creases, residual copper and the like, the above defects can all induce CAF failure of the circuit board 1, the above defects are detected and repaired, and the purpose of controlling CAF failure of the circuit board 1 can be achieved. The detection means also includes ion contamination test (performed according to IPC-TM-650 2.3.25), to ensure that the cleanliness of the board surface is ≤10 us / cm².

[0035] S5, detecting the circuit board 1 under the environment of 85℃ / 85%RH, and selecting good circuit boards 1 without CAF failure. The application finally also adopts detection means to control CAF failure of the circuit board 1, and the rated voltage is applied on the circuit board 1 under high temperature and high humidity environment, to induce CAF failure of poor circuit boards 1, and remove the poor circuit boards 1, and keep the good circuit boards 1, so as to realize the control of CAF failure of the circuit board 1.

[0036] In the application, the circuit board 1 with CAF failure in the test process is analyzed, and the analysis means specifically includes: slice analysis: slicing the failure sample, and observing the CAF channel shape (such as glass fiber hollow, candle effect). Data comparison: combining the parameters provided by the material supplier (such as glass fiber hollow rate) and the process record, and positioning the failure source.

[0037] Specifically, in the material preparation stage, the application selects high-quality insulating cloth layer 103 with compact glass fiber and glass fiber hollow ≤30ppm as the raw material of the insulating cloth layer 103 of the circuit board 1, so as to inhibit the possibility of CAF failure of the circuit board 1 from the raw material selection stage. The application increases the copper foil line width compensation, increases the etching rate, optimizes the drilling parameters, and performs image full detection on the circuit board 1, to inhibit the possibility of CAF failure of the circuit board 1 in multiple aspects in the process stage. The application monitors CAF failure under high temperature and high humidity environment, induces CAF failure of poor circuit boards 1, removes the poor circuit boards 1, and keeps the good circuit boards 1, so as to realize the control of CAF failure of the circuit board 1. Through the above steps, the application comprehensively considers the three factors of material, process and environment, constructs a multi-dimensional control model, effectively inhibits the possibility of CAF failure of the circuit board 1, reduces the economic loss caused by CAF failure, and improves the long-term reliability of the circuit board 1.

[0038] Referring to Figure 3 As shown in FIG. 1, in some embodiments, the above S3 includes the following step: S31, inputting each hole position of the circuit board 1 into the drilling equipment; inputting the preset drilling position on the circuit board 1 into the drilling equipment, and the drilling equipment will automatically drill according to the inputted preset drilling position, to form the corresponding hole position.

[0039] S32, determine the basic drilling position, the drilling equipment first forms the basic drilling position; in the initial stage, the hole position at the upper left corner is the basic drilling position, and the basic drilling position is also the first hole position drilled by the drilling equipment on the circuit board 1;

[0040] S33, obtain the interval D between the hole position adjacent to the basic drilling position and the basic drilling position, when D is greater than or equal to 7.5mm, the drilling equipment forms the hole position adjacent to the basic drilling position; since the customer's demand for the circuit board 1 is different, the hole position interval on the circuit board 1 cannot be controlled by the production end, so different drilling methods should be selected according to the hole position interval when drilling, the method for obtaining the hole position adjacent to the basic drilling position is to obtain the adjacent hole position to the right first, when there is no hole position to the right, obtain the adjacent hole position to the bottom, ignore the drilled hole position, and after drilling to the lower right corner, find the adjacent hole position in reverse, until all the hole positions are drilled.

[0041] When D is less than 7.5mm, ignore the hole position adjacent to the basic drilling position, obtain the interval D between the hole position adjacent to the basic drilling position and the basic drilling position, and repeat the above comparison steps; when D is less than 7.5mm, in order to avoid continuous high temperature damage to the insulating layer material, the method of skipping drilling is adopted, the hole position adjacent to the basic drilling position is ignored, and then the hole position adjacent to the hole position adjacent to the basic drilling position is found, which is called the second adjacent hole position in the present application, and the interval D between the second adjacent hole position and the basic drilling position is obtained, when D is less than 7.5mm, drilling starts at the second adjacent hole position, when D is less than 7.5mm, the interval D between the hole position adjacent to the second adjacent hole position and the basic drilling position is found again, and the comparison is continued, generally the interval D between the second adjacent hole position and the basic drilling position is greater than or equal to 7.5mm;

[0042] S34, take the just formed hole position as a new basic drilling position, and repeat step S33. The drilled hole position is always ignored, and the required hole is drilled on the preset drilling position on the circuit board 1 through the above method. In the present application, adjacent means the smallest interval, when there are multiple hole positions to the right of the basic drilling position, the hole position with the smallest interval from the basic drilling position is taken as the hole position adjacent to the basic drilling position.

[0043] In some embodiments, the above S32 specifically comprises the following steps: the rotating speed of the drilling head 7 of the drilling equipment is 30000-36000rpm. Low drilling speed is adopted to avoid excessive temperature rise and damage to the insulating layer material of the circuit board 1, and the down-cut rate of the drilling head 7 is about 0.7-1m / min.

[0044] Referring to Figure 4 Figure 5As shown in the drawings, in some embodiments, the drilling device comprises: a rack 15; the rack 15 is the structural basis of the drilling device, and other structures on the drilling device are directly or indirectly connected to the rack 15. A drilling platform 10 is movably arranged on the rack 15; the drilling platform 10 is longitudinally movable along the rack 15, the length direction of the rack 15 is the longitudinal direction, the width direction of the rack 15 is the transverse direction, and the height direction of the rack 15 is the vertical direction. A transverse carriage 3 is movably arranged on the rack 15; the transverse carriage 3 is transversely movable along the rack 15; a drill table is movably arranged on the transverse carriage 3, and a drill bit 7 is arranged on the drill table; the drill table is vertically movable along the transverse carriage 3, thereby driving the drill bit 7 to drill holes on the circuit board 1. A drill bit 7 drive 4 is arranged on the drill table and connected to the drill bit 7; the drill bit 7 drive 4 is used to drive the drill bit 7 to rotate, thereby driving the drill bit 7 to drill holes on the circuit board 1. A limiting piece 9 is installed on the drilling platform 10, and a limiting cavity is arranged in the limiting piece 9, and the circuit board 1 is located in the limiting cavity; the limiting cavity in the limiting piece 9 is used to place the circuit board 1. A pressing piece 8 is arranged on the limiting piece 9 and abuts against the circuit board 1. The pressing piece 8 is used to press the circuit board 1, so as to avoid movement of the circuit board 1 relative to the drilling platform 10 in the process of drilling. Through the longitudinally movable drilling platform 10 and the transversely movable transverse carriage 3, the drill bit 7 can contact any position on the circuit board, so as to drill corresponding holes on the corresponding positions on the circuit board 1.

[0045] In this embodiment, the pressing piece 8 is installed on the limiting piece 9 by a fastener, and the fastener is preferably a screw.

[0046] As shown in the drawings, Figure 4 , Figure 5 and Figure 6 , in some embodiments, the drilling device further comprises: a bottom pad layer 19, the bottom pad layer 19 is located at the bottom of the limiting cavity, the circuit board 1 is located in the limiting cavity and above the bottom pad layer 19; the material of the bottom pad layer 19 is a high-density melamine pad, and the bottom pad layer 19 is provided with a blind hole corresponding to a through hole of an aluminum plate layer 17; the aluminum plate layer 17 is arranged in the limiting cavity and above the circuit board 1, and the aluminum plate layer 17 is provided with a through hole matched with the hole of the circuit board 1. The inner diameters of the blind hole and the through hole are slightly larger than the outer diameter of the drill bit 7. The aluminum plate layer 17 can protect the circuit structure of the circuit board 1, and the arrangement of the aluminum plate layer 17 is also conducive to heat dissipation generated by drilling.

[0047] As shown in the drawings, Figure 4 , Figure 5 and Figure 6As shown in the figure, in some embodiments, further comprising: cutting fluid, the cutting fluid is stored in the through hole; sealing layer 18, the sealing layer 18 is arranged at the bottom of the through hole; aluminum film layer 16, the aluminum film layer 16 is arranged in the limiting cavity and is located above the aluminum plate layer 17. The pressing member 8 abuts against the aluminum film layer 16, and the sealing layer 18 is arranged at the bottom of the through hole of the aluminum plate layer 17, so that the aluminum plate layer 17 can store a certain amount of cutting fluid. In the process of drilling, the cutting fluid can absorb the heat generated by the drill bit 7, avoid excessive temperature rise of the drill bit 7, and achieve the purpose of protecting the insulating layer material, thereby reducing the possibility of CAF failure of the circuit board 1.

[0048] In the present embodiment, the blind hole and the through hole are arranged to avoid the drill bit 7 from contacting the aluminum plate layer 17 or the bottom pad layer 19 to generate heat. The material of the sealing layer 18 can also be a resin material, which can be reformed after being damaged by the drill bit 7. After drilling is completed, the cutting fluid flows into the blind hole of the bottom pad layer 19. Through the above structure, the position of the cutting fluid can be strictly controlled to effectively cool the cutting fluid and avoid affecting the circuit structure of the circuit board 1. The arrangement of the aluminum film layer 16 is beneficial to prevent the cutting fluid from overflowing and spilling during drilling. Due to the arrangement of the pressing member 8, the cutting fluid is not easy to flow from the gap between the circuit board 1 and the aluminum plate layer 17 or the gap between the circuit board 1 and the bottom pad layer 19 to the circuit board 1.

[0049] Referring to Figure 4 and Figure 5 As shown in the figure, in some embodiments, further comprising: longitudinal movement drive 2, the longitudinal movement drive 2 is arranged on the rack 15 and connected to the drilling platform 10; the longitudinal movement drive 2 is a motor, the longitudinal movement drive 2 is connected with a screw rod, the screw rod is connected with a nut block, the nut block is connected with the drilling platform 10, so that the drilling platform 10 is driven by the longitudinal movement drive 2 to move longitudinally. The rack 15 is further provided with a bearing seat 12, the bearing seat 12 is installed with a bearing 13, one end of the screw rod is connected with the longitudinal movement drive 2, and the other end of the screw rod is connected with the bearing 13. The rack 15 is further provided with a guide rail frame 11, the guide rail frame 11 is provided with a guide rail 14, the drilling platform 10 is installed with a first sliding block matched with the guide rail 14, and the stability of the movement of the drilling platform 10 is enhanced through the cooperation of the guide rail 14 and the first sliding block. The horizontal movement drive 6 is arranged on the rack 15 and connected with the horizontal movement frame 3; the horizontal movement drive 6 drives the horizontal movement frame 3 to move, and the principle is the same as that of the longitudinal movement drive 2 driving the drilling platform 10 to move, which will not be repeated here. The vertical movement drive 5 is arranged on the horizontal movement frame 3 and connected with the drilling table. The vertical movement drive 5 is a hydraulic cylinder, the vertical movement drive 5 is provided with an extendable output rod, and the output rod is connected with the drilling table. The horizontal movement frame 3 is provided with a sliding groove, and the drilling table is provided with a second sliding block matched therewith, so as to enhance the stability of the movement of the drilling table through the cooperation of the second sliding block and the sliding groove.

[0050] In some embodiments, the image detection method in S4 is as follows: the circuit board 1 is detected by ccd to determine whether the circuit board 1 has scratches and impurities. Preferably, the X-ray detection hole alignment degree is used to screen samples with a concentric circle interval of ≤2 Mil to ensure that there is no layer deviation defect.

[0051] In some embodiments, the circuit board 1 detection method in S5 is as follows: the rated voltage is applied to the circuit board 1, and the ion migration current in the insulating layer of the circuit board 1 is monitored in real time by a high-precision conductivity meter for continuous testing for 500 hours. The high-precision conductivity meter measures the change of the conductivity of the insulating layer, thereby detecting the ion migration current in the insulating layer in real time, and determining whether there is a CAF failure. The rated voltage is the working voltage of the circuit board 1.

[0052] In some embodiments, the circuit board 1 detection method in S5 is as follows: the rated voltage is applied to the circuit board 1, and the temperature rise of each region of the circuit board 1 is detected by an infrared imager for continuous testing for 500 hours. After the rated voltage is applied, the lines and electrical components on the circuit board 1 will heat up, and the regions without lines or electrical components will not heat up. The abnormal heating points on the circuit board 1 are found by the infrared image in the orthographic projection direction of the circuit board 1. When there is abnormal heating, it is determined that the insulating layer material of the part has a CAF failure.

[0053] The present application provides two CAF failure detection methods, which can be selected for detection in actual use, and of course both detection methods can be used at the same time to improve the detection rate of CAF failure. The long-term reliability of the circuit board 1 is improved.

[0054] The above only describes some or preferred embodiments of the present application, and neither the text nor the drawings can limit the scope of protection of the present application. Any equivalent structural transformation based on the content of the present application and the drawings, or direct / indirect application in other related technical fields is included in the scope of protection of the present application.

Claims

1. A method for controlling CAF failure in a circuit board, characterized in that, The control method is as follows: S1. The degree of looseness and hollowness of the glass fiber in the insulating cloth layer is detected by microscopy. Cloth layers with more than 30 ppm of hollow glass fiber are rejected. S2. Increase the linewidth compensation of the copper foil and increase the etching rate of the copper foil to avoid the formation of copper teeth on the copper foil; S3. Drill holes in the circuit board using drilling equipment; S4. Detect and repair defects on the circuit board using image detection. S5. Test the circuit board in an environment of 85℃ / 85%RH and select good circuit boards that have not experienced CAF failure. The drilling equipment includes: frame; A drilling platform, which is movably mounted on the frame; A transverse frame, which is movably mounted on the frame; A drilling platform, which is movably mounted on the transverse frame, and a drill bit is rotatably mounted on the drilling platform; A drill bit drive, which is disposed on the drill rig and connected to the drill bit; A limiting component is installed on the drilling platform, and a limiting cavity is provided inside the limiting component, with the circuit board located inside the limiting cavity; A clamping member is disposed on the limiting member and abuts against the circuit board; Also includes: A bottom pad layer is located at the bottom of the limiting cavity, and the circuit board is located inside the limiting cavity and above the bottom pad layer; An aluminum plate layer is disposed within the limiting cavity and located on the circuit board, and the aluminum plate layer is provided with through holes adapted to the hole positions of the circuit board. Also includes: Cutting fluid, wherein the through-hole stores cutting fluid; A sealing layer is disposed at the bottom of the through hole; An aluminum film layer is disposed within the limiting cavity and located above the aluminum plate layer.

2. The method for controlling CAF failure of a circuit board according to claim 1, characterized in that, The above S3 includes the following steps: S31. Input the positions of each hole on the circuit board into the drilling equipment; S32. Determine the basic drilling position; the drilling equipment first forms the basic drilling position. S33. Obtain the distance D between the hole position adjacent to the basic drilling position and the basic drilling position. When D is greater than or equal to 7.5 mm, the drilling equipment forms a hole position adjacent to the basic drilling position. When D is less than 7.5mm, ignore the holes adjacent to the basic drill hole position, obtain the distance D between the holes adjacent to the basic drill hole position and the basic drill hole position, and repeat the above comparison steps. S34. Using the newly formed hole position as the new base drilling position, repeat step S33.

3. The method for controlling CAF failure of a circuit board according to claim 2, characterized in that, The above-mentioned S32 specifically includes the following steps: the rotation speed of the drill bit of the drilling equipment is 30,000 rpm to 36,000 rpm.

4. The method for controlling CAF failure of a circuit board according to claim 1, characterized in that, Also includes: A longitudinal traverse drive, which is mounted on the frame and connected to the drilling platform; A transverse drive, which is mounted on the frame and connected to the transverse frame; A vertical movement drive is mounted on the horizontal movement frame and connected to the drill rig.

5. The method for controlling CAF failure of a circuit board according to claim 1, characterized in that, The image detection method in S4 above is as follows: a full inspection of the circuit board is performed by CCD detection to determine whether the circuit board has scratches or debris.

6. The method for controlling CAF failure of a circuit board according to claim 1, characterized in that, The circuit board testing method in S5 above is as follows: apply a rated voltage to the circuit board, monitor the ion migration current in the insulating layer of the circuit board in real time using a high-precision conductivity meter, and continuously test for 500 hours.

7. The method for controlling CAF failure of a circuit board according to claim 1, characterized in that, The circuit board testing method in S5 above is as follows: apply a rated voltage to the circuit board, detect the temperature rise in each area of ​​the circuit board using an infrared imager, and continue testing for 500 hours.

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