A tool and method for detecting residual metal in back drilling of PCB board

Abstract

The present invention discloses a tool and method for detecting residual metal in a back-drilled hole of a PCB board in the technical field of back-drilled holes of a PCB board, aiming to solve the technical problem that most of the residual metal in the back-drilled hole in the prior art is not exposed on the surface, and it is difficult to judge whether there is residual metal in the back-drilled hole. A tool for detecting residual metal in a back-drilled hole of a PCB board comprises an insulating probe, the insulating probe is connected to a guide rod, the guide rod is installed in a shell, and the shell is connected to a conductive part. The present invention designs a detection tool, extends the detection tool into the back-drilled hole, and inputs a detection current through the conductive part. If it is short-circuited, it means that there is residual metal on the side wall of the back-drilled hole; if it is open-circuited, it means that there is no residual metal on the side wall of the back-drilled hole. It can quickly judge whether there is residual metal in the back-drilled hole. The tool is exquisitely designed, simple to operate, high in detection accuracy, high in detection efficiency, and low in cost.

Description

Technical Field

[0001] The invention belongs to the technical field of back drilling of PCB boards, and in particular relates to a tool and a method for detecting residual metal in back drilling of PCB boards. Background Art

[0002] In the PCB (printed circuit board) production process, the back drilling process is often used. The purpose of back drilling is to drill out the through-hole sections that do not play any connection or transmission role, so as to avoid the reflection, scattering, delay and other "distortion" problems of high-speed signal transmission. In the back drilling process, the back drilling hole is often skewed due to inaccurate back drilling positioning, and metals such as copper plating remain in the back drilling hole. The back drilling residual copper is connected to the front copper of the conductive hole, but most of the back drilling residues are not exposed on the surface, and optical monitoring cannot detect small holes or deeper back drilling. The capacitance method cannot identify the holes after etching. Summary of the invention

[0003] The purpose of the present invention is to provide a tool and method for detecting residual metal in back-drilled holes of PCB boards, so as to solve the technical problem in the prior art that most of the residual metal in back-drilled holes is not exposed on the surface, making it difficult to determine whether there is residual metal in the back-drilled holes.

[0004] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a tool for detecting residual metal in the back drilling of a PCB board, comprising an insulating probe, the insulating probe is connected to a guide rod, the guide rod is installed in a shell, and the shell is connected to a conductive part.

[0005] The insulating probe is spindle-shaped.

[0006] The conducting part comprises a plurality of elastic metal sheets, one ends of the plurality of elastic metal sheets are connected to each other and surround the guide rod, and the other ends of the elastic metal sheets have a wedge-shaped structure.

[0007] The insulating probe is in a cone shape, and the bottom surface of the cone is connected to the guide rod.

[0008] The conducting portion is a conductive spring.

[0009] The guide rod is provided with a limit block, the shell is provided with an expansion section, and the limit block is located inside the expansion section.

[0010] The guide rod is provided with a return spring, one end of the return spring is connected to the housing and the other end is connected to the limit block.

[0011] A method for detecting residual metal in a back-drilled hole of a PCB board, comprising:

[0012] Insert the guide rod connected to the insulation probe into the back-drilled hole of the PCB board so that the insulation probe abuts against the bottom of the back-drilled hole;

[0013] The conducting part is pushed by the shell outside the guide rod, and the conducting part is squeezed by the shell and the insulating probe to expand outward to form a trumpet shape and abut against the side wall of the back-drilled hole;

[0014] A detection current is connected to the conductive part. If it shows a short circuit, it means that there is residual metal on the side wall of the back-drilled hole; if it shows an open circuit, it means that there is no residual metal on the side wall of the back-drilled hole.

[0015] The shell is made of metal, and the detection current is conducted to the conducting part through the shell.

[0016] The shell is made of non-metal, and the detection current is conducted to the conducting part through electrodes arranged on the shell.

[0017] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: the present invention designs a detection tooling, extends the detection tooling into the back-drilled hole, and inputs a detection current through a conductive part. If a short circuit occurs, it indicates that there is residual metal on the side wall of the back-drilled hole; if an open circuit occurs, it indicates that there is no residual metal on the side wall of the back-drilled hole. It is possible to quickly determine whether there is residual metal inside the back-drilled hole, and the tooling is sophisticated in design, simple to operate, with high detection accuracy, high detection efficiency, and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The structure of a tool for detecting residual metal in a back-drilled hole of a PCB board provided in the first embodiment of the present invention is schematically shown. Figure 1 ;

[0019] Figure 2 The structure of a tool for detecting residual metal in a back-drilled hole of a PCB board provided in the first embodiment of the present invention is schematically shown. Figure 2 ;

[0020] Figure 3 Different states of a tool for detecting residual metal in a back-drilled hole of a PCB board provided in the first embodiment of the present invention during the process of detecting residual metal;

[0021] Figure 4 This is a schematic diagram of the principle of a method for detecting residual metal in a back-drilled hole of a PCB board provided in Embodiment 1 of the present invention to determine whether there is residual metal;

[0022] Figure 5 The structure of a tool for detecting residual metal in a back-drilled hole of a PCB board provided in the second embodiment of the present invention is schematically shown. Figure 1 ;

[0023] Figure 6 The structure of a tool for detecting residual metal in a back-drilled hole of a PCB board provided in the second embodiment of the present invention is schematically shown. Figure 2 ;

[0024] Figure 7Different states of a tool for detecting residual metal in a back-drilled hole of a PCB board provided in the second embodiment of the present invention during the process of detecting residual metal;

[0025] Figure 8 The present invention is a schematic diagram showing the principle of a method for detecting residual metal in a back-drilled hole of a PCB board provided in a second embodiment of the present invention to determine whether there is residual metal. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0027] It should be noted that in the description of the present invention, the directions or positional relationships indicated by the terms "front", "rear", "left", "right", "up", "down", "inside", "outside", etc. are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention rather than requiring the present invention to be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. The terms "front", "rear", "left", "right", "up", and "down" used in the description of the present invention refer to the directions in the accompanying drawings, and the terms "inside" and "outside" refer to the directions toward or away from the geometric center of a specific component, respectively.

[0028] Embodiment 1:

[0029] like Figure 1 , Figure 2As shown, a tool for detecting residual metal in the back drilling of a PCB board, a spindle-shaped insulating probe 1 is connected to a guide rod 2, the guide rod 2 is installed in a shell 3, a conducting part is provided on the shell 3, the conducting part includes at least two elastic metal sheets 41, one ends of these elastic metal sheets 41 are interconnected and surround the guide rod 2, the elastic metal sheet 41 can be a part that is arranged on the shell 3 and is independent of the shell 3, in this case, the shell 3 part can be made of metal material or non-metallic material; the elastic metal sheet 41 can also be formed as a whole with the shell and then formed by cutting; the other end of the elastic metal sheet 41 has a wedge structure, and the wedge structure facilitates the spindle-shaped insulating probe 1 to open the metal sheet 41. A limit block 21 is provided on the guide rod 2, and an expansion section 31 is provided on the shell 3. The limit block 21 is located inside the expansion section 31. A return spring 5 is provided on the guide rod 2, and one end of the return spring 5 is connected to the shell 3 and the other end is connected to the limit block 21. When not in use, the return spring 5 pushes the guide rod 2 to the side of the conducting part of the shell 3 through the limit block 21. At this time, the elastic metal sheet 41 is in a contracted state and surrounds the guide rod 2. The expansion section 31 and the limit block 21 cooperate with each other to limit the displacement of the guide rod 2 along its axial direction to prevent the guide rod 2 from slipping out of the shell 3; when in use, the shell 3 and the insulating probe 1 move toward each other to squeeze the conducting part, the elastic metal sheet 41 is stretched open, and the limit block 21 moves in the expansion section 31 to the side of the conducting part away from the shell 3 to compress the return spring 5.

[0030] Method for detecting residual metal in back drilling of PCB board using the tooling provided in this embodiment:

[0031] Insert the guide rod 2 connected to the insulating probe 1 into the back-drilled hole of the PCB board, so that the insulating probe 1 abuts against the bottom of the back-drilled hole;

[0032] The conducting part is pushed by the shell 3 outside the guide rod 2, and the conducting part is squeezed by the shell 3 and the insulating probe 1 to expand outward to form a trumpet shape and abut against the side wall of the back-drilled hole;

[0033] A detection current is connected to the conducting part through a probe. If the shell is made of metal, the detection current can be conducted to the conducting part through the shell. If the shell is made of non-metal, the detection current is conducted to the conducting part through an electrode arranged on the shell (i.e., a wire is arranged on the shell, one end of the wire is connected to the conducting part, and the other end is connected to the detection probe); another probe is used as a ground terminal, thereby connecting to form a complete circuit;

[0034] If a short circuit is detected during the detection process, it means that there is residual metal on the side wall of the back-drilled hole; if an open circuit is detected during the detection process, it means that there is no residual metal on the side wall of the back-drilled hole.

[0035] like Figure 3As shown, a schematic diagram of the detection process of whether there is residual copper in the back-drilled hole of the PCB board by the tooling provided in this embodiment, when the insulating probe contacts the bottom of the back-drilled hole, continue to press down the shell so that the elastic metal sheet is stretched to form a trumpet-shaped structure and contacts the inner wall of the back-drilled hole, and connect the detection current to the elastic metal sheet through a probe, and the other probe is used as the ground terminal, so as to connect to a complete circuit. Loosening the shell can make the trumpet-shaped elastic metal sheet shrink back to its original state so that the tooling is lifted out of the back-drilled hole and moved to the next back-drilled hole to be tested. In the figure, a represents the state where the tooling is placed in the back-drilled hole to be tested; b represents the state where the elastic metal sheet is stretched to form a trumpet-shaped structure abutting against the inner wall of the back-drilled hole; c represents the state where the tooling is removed from the back-drilled hole after the detection.

[0036] like Figure 4 As shown, n represents the residual copper in the back-drilled hole of the PCB board, and m represents the normal copper plating on the PCB board; if it appears as a short circuit during the detection process, it means that there is residual copper n on the side wall of the back-drilled hole, as shown in state d, the elastic metal sheet is stretched to form a trumpet-shaped structure abutting against the inner wall of the back-drilled hole, and the residual copper n in the back-drilled hole makes the circuit appear as a short circuit; if it appears as an open circuit during the detection process, it means that there is no residual copper on the side wall of the back-drilled hole, as shown in state e. The detection tooling and detection method of the present invention can quickly determine whether there is residual metal inside the back-drilled hole, and the tooling design is exquisite, the operation is simple, the detection accuracy is high, the detection efficiency is high, and the cost is low.

[0037] Implementation 2:

[0038] like Figure 5 , Figure 6 As shown, the difference between this embodiment and the first embodiment is that the insulating probe 1 is a conical structure, the bottom surface of the cone is connected to the guide rod 2, and the conductive part is a conductive spring 42. The conductive spring 42 is sleeved on the guide rod 2, one end of which is connected to the insulating probe 1, and the other end is connected to the housing 3. When not in use, the reset spring 5 pushes the guide rod 2 to the conductive part side of the housing 3 through the limit block 21, and the conductive spring 42 is in a free state at this time; when in use, the housing 3 and the insulating probe 1 move toward each other to squeeze the conductive part, and the conductive spring 42 is squeezed to produce radial displacement.

[0039] The method for detecting the residual metal in the back-drilled hole of the PCB board using the tooling provided in this embodiment is exactly the same as that in the first embodiment.

[0040] like Figure 7The figure shows a schematic diagram of the detection process of using the tooling described in this embodiment to detect whether there is residual copper in the back-drilled hole of the PCB board. After the insulating probe contacts the bottom of the back-drilled hole, the shell is pressed down continuously so that the conductive spring is stretched to form a trumpet-shaped structure and contacts the inner wall of the back-drilled hole. A detection current is connected to the conductive spring through a probe, and the other probe is used as the ground terminal, thereby connecting to a complete circuit. Loosening the shell can cause the trumpet-shaped conductive spring to shrink back to its original state so that the tooling is lifted out of the back-drilled hole and moved to the next back-drilled hole to be tested. In the figure, a represents the state in which the tooling is placed in the back-drilled hole to be tested; b represents the state in which the conductive spring is stretched to form a trumpet-shaped structure abutting against the inner wall of the back-drilled hole; and c represents the state in which the tooling is removed from the back-drilled hole after the detection.

[0041] like Figure 8 As shown, n represents the residual copper in the back-drilled hole of the PCB board, and m represents the normal copper plating on the PCB board; if a short circuit is shown during the detection process, it means that there is residual copper n on the side wall of the back-drilled hole, as shown in state d, the conductive spring is stretched to form a trumpet-shaped structure abutting against the inner wall of the back-drilled hole, and the residual copper n in the back-drilled hole makes the circuit appear short-circuited; if an open circuit is shown during the detection process, it means that there is no residual copper on the side wall of the back-drilled hole, as shown in state e.

[0042] The invention provides two tools and methods for detecting back-drilled residual copper. The tools can be installed on a common test needle bed, a flying probe test head, or a drilling machine with an electrical test function.

[0043] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A tool for detecting residual metal in back drilling of PCB boards, characterized in that: It includes an insulating probe, the insulating probe is connected to a guide rod, the guide rod is installed in a shell, and the shell is connected to a conducting part; When the insulating probe is spindle-shaped, the conducting portion comprises a plurality of elastic metal sheets, one end of each of the plurality of elastic metal sheets is connected to each other and surrounds the guide rod, and the other end of each of the elastic metal sheets has a wedge-shaped structure; When the insulating probe is in a cone shape, the bottom surface of the cone is connected to the guide rod, and the conducting part is a conductive spring; The guide rod is provided with a limit block, the shell is provided with an expansion section, and the limit block is located inside the expansion section; The guide rod is provided with a return spring, one end of the return spring is connected to the housing and the other end is connected to the limit block.

2. A method for detecting residual metal in back-drilled holes of PCB boards, characterized in that: Using the tooling for detecting residual metal in back drilling of a PCB board according to claim 1, the method comprises: Insert the guide rod connected to the insulation probe into the back-drilled hole of the PCB board so that the insulation probe abuts against the bottom of the back-drilled hole; The conducting part is pushed by the shell outside the guide rod, and the conducting part is squeezed by the shell and the insulating probe to expand outward to form a trumpet shape and abut against the side wall of the back-drilled hole; Connect the detection current to the conductive part. If it is short-circuited, it means that there is residual metal on the side wall of the back-drilled hole; if it is open-circuited, it means that there is no residual metal on the side wall of the back-drilled hole. The shell is made of metal, and the detection current is conducted to the conducting part through the shell; The shell is made of non-metal, and the detection current is conducted to the conducting part through electrodes arranged on the shell.

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