Flexible eddy current array detection probe

Abstract

The present subject matter can include a flexible Eddy Current Array (ECA) probe assembly that is capable of conforming to complex profiles of a structure under test, without causing damage to the probe assembly; the structure being, for example, a structure having curved portions extending in two orthogonal directions (e.g., the structure under test can have complex surface curvature in both the index and scan axes). The ECA probe assembly can include a slot structure that extends through a flexible Printed Circuit Board (PCB) assembly or other substrate, facilitating flexure and bending.

Description

Technical Field

[0001] This document relates generally, but not in a limited way, to apparatuses and techniques for nondestructive testing, such as apparatuses and techniques for facilitating eddy current testing, and more specifically to apparatuses and techniques including flexible eddy current array (ECA) sensor assemblies capable of conforming to curved or other complex surface profiles. Background Technology

[0002] Non-destructive testing (NDT) refers to the use of one or more different techniques to: inspect the surface or internal areas of a workpiece (DUT) to determine the presence of cracks or defects; or to characterize the DUT for other purposes. One type of NDT may include eddy current testing, in which electromagnetic energy is applied to the DUT, induced currents generated on or within the DUT are detected, and the detected current value (or associated impedance value) indicates the structure of the DUT, such as the presence of cracks, porosity, looseness, or other inhomogeneities. Typically, eddy current (EC) sensors contain one or more sensor elements, such as induction coils that can be excited by alternating current (AC) power. Such coils (or other electromagnetic sensing elements such as Hall sensors) can be used to receive signals indicating induced eddy currents on or within the surface of the structure under test. Summary of the Invention

[0003] In one aspect, this disclosure provides a circuit arrangement for an eddy current array (ECA) probe. The arrangement may include a substrate, a coil array, and conductive traces. The substrate may include: a sensing region located at a first end of the substrate; a wiring region located at a second end of the substrate opposite to the first end; and an intermediate region extending between the sensing region and the wiring region. The coil array may be defined within the sensing region and arranged laterally along the sensing region. The conductive traces may be defined within the intermediate region and the wiring region and extend longitudinally along the intermediate region and the wiring region for coupling the coil array to a probe connector of the ECA probe. A longitudinal slot may be defined in the intermediate region of the substrate, located between at least some of the conductive traces, to mechanically decouple the curvature of the sensing region from the wiring region.

[0004] In one aspect, this disclosure provides an eddy current array (ECA) sensing assembly. The ECA sensing assembly may include a probe and a acquisition device. The probe may include a circuit board and a resilient backing, the circuit board having a coil array, and the resilient backing being positionable to abut a surface of the circuit board. The acquisition device may be operatively coupled to the coil array to achieve a predetermined timing coil excitation sequence and acquire corresponding eddy current signals. The circuit board may further include a substrate and conductive traces. The substrate may include a sensing region located at a first end thereof, and the coil array may be defined within and laterally arranged along the sensing region. The substrate may further include: a wiring region located at a second end of the substrate opposite to the first end; and an intermediate region extending between the sensing region and the wiring region. The conductive traces may be defined within and longitudinally extending along the intermediate and wiring regions for coupling the coil array to the acquisition device. A longitudinal slot may be defined in the intermediate region of the substrate, located between at least some of the conductive traces. When the probe is pressed against a workpiece under test, the resilient backing may cause the sensing region of the substrate to bend to conform to the contour of the workpiece under test. The longitudinal slot can mechanically decouple the bending of the sensing area from the wiring area.

[0005] In one aspect, this disclosure provides a circuit arrangement for an eddy current array (ECA) probe. The arrangement may include a substrate, a coil array, and conductive traces. The substrate may include: a sensing region located at a first end of the substrate; a wiring region located at a second end of the substrate opposite to the first end; and an intermediate region extending between the sensing region and the wiring region. The coil array may be defined within the sensing region. The conductive traces may be defined within and extend along the intermediate and wiring regions for coupling the coil array to a probe connector of the ECA probe. A longitudinal slot may be defined within the intermediate region of the substrate. An elastic backing of the ECA probe may cause the sensing region of the substrate to bend to conform to the contour of a device under test (e.g., when the ECA probe is pressed against the device under test). The longitudinal slot may mechanically decouple the bending of the sensing region from the wiring region. Attached Figure Description

[0006] Figure 1 It is a test piece having regions that bend in multiple directions, according to at least one embodiment of the present disclosure.

[0007] Figure 2 This is a top view of a circuit arrangement for an eddy current array (ECA) probe according to at least one embodiment of the present disclosure.

[0008] Figure 3 According to at least one embodiment of this disclosure Figure 2 A magnified view of a portion of the sensing area of ​​the circuit device.

[0009] Figure 4 It is a circuit arrangement for an eddy current array (ECA) probe comprising a four-layer substrate, according to at least one embodiment of the present disclosure.

[0010] Figure 5 According to at least one embodiment of this disclosure Figure 4 The first layer of the circuit device.

[0011] Figure 6 According to at least one embodiment of this disclosure Figure 4 The second layer of the circuit device.

[0012] Figure 7 According to at least one embodiment of this disclosure Figure 4 The third layer of the circuit device.

[0013] Figure 8 According to at least one embodiment of this disclosure Figure 4 The fourth layer of the circuit device.

[0014] Figure 9 An impedance plane schematic diagram and an image diagram illustrating a defect indication that can be obtained using an ECA sensing component, according to at least one embodiment of the present disclosure, are shown.

[0015] Figure 10 This is a schematic diagram of an ECA sensing component according to at least one embodiment of the present disclosure.

[0016] Figure 11 This is a perspective view of an ECA probe assembly according to at least one embodiment of the present disclosure.

[0017] Figure 12 This is an image of a printed circuit board showing an ECA probe attached to a complex region of the test subject according to at least one embodiment of the present disclosure. Detailed Implementation

[0018] Eddy current array (ECA) probes can be fabricated using flexible printed circuit board (PCB) materials. This flexible component can adapt to different surface shapes of the structure being inspected. However, even when fabricated using flexible PCB materials, commercially available conventional probes may still suffer from high stiffness and are generally not stretchable (e.g., such ECA sensors cannot be extended). For example, commercially available ECA sensors may include strip-like structures (e.g., approximately 2.54 cm or approximately 1 inch wide), a construction that limits the probe's ability to adhere to certain surfaces. For instance, commercially available flexible probes may not be able to adhere to complex contours that are concave along the scanning axis, or contours that have curvature in two directions simultaneously (e.g., the root region of a turbine blade).

[0019] Figure 1 The diagram shows a test piece 100, whose region 102 has a curvature in both a first direction 104 and a second direction 106. Commercially available ECA probes may struggle to conform to a profile with curvature in both directions simultaneously. For example, a flexible printed circuit board (PCB) can be bent sufficiently to conform to curvature present only in the first or second direction. However, a flexible PCB may not be able to bend sufficiently along curvature present in both directions simultaneously, causing a portion of the sensing area of ​​the flexible PCB (i.e., the area on the substrate containing the ECA) to detach from the surface of the test piece. This detachment reduces the coupling effect between the coil and the test piece surface, thereby reducing the sensitivity and accuracy of eddy current detection. In particular, areas of the sensing area that are not in close contact with the test piece will experience a more severe lift-off effect, leading to signal strength attenuation, increased noise, and unreliable detection of cracks or abnormal defects. Furthermore, uneven overall contact of the sensing area can cause deviations in the acquired data, increasing the difficulty of interpreting the detection results and potentially causing missed defects.

[0020] This disclosure provides a variety of apparatuses and techniques for ECA testing, which can solve many challenges encountered in the inspection of various surfaces of the test piece. For example, the subject of this invention includes a flexible ECA probe assembly that can better conform to complex contours extending in two orthogonal directions (e.g., the test structure has complex surface curvatures on both the index axis and the scan axis) without damaging the probe assembly.

[0021] According to various embodiments, this disclosure provides a circuit arrangement for an eddy current array (ECA) probe. This circuit arrangement can be implemented as a printed circuit board (PCB), such as a flexible PCB. As further described below, the circuit arrangement is designed to conform to the complex surfaces of the test object.

[0022] The circuitry may include: a coil array for generating and detecting eddy currents; and conductive traces for electrically coupling the coil array to a probe connector of an ECA probe and / or a multiplexer unit integrated into the probe. The coupling of the coil array to the probe connector allows the probe and / or acquisition device to excite the coil array to generate and detect eddy currents. During operation, the acquisition device can selectively energize the coils and acquire nondestructive testing (NDT) data from the device under test.

[0023] The circuit device includes a substrate. The substrate can be formed of a flexible material such as polyimide, which combines electrical insulation properties with mechanical flexibility. Other suitable materials for the substrate may include polyester (PET), polyethylene naphthalate (PEN), liquid crystal polymer (LCP), polytetrafluoroethylene (PTFE), and aramid fiber (Nomex).

[0024] Coils and traces can be defined on a substrate using copper or other conductive materials and patterned using photolithography and etching processes. Other conductive materials suitable for defining coils and traces may include aluminum, silver, gold, nickel, and conductive alloys such as copper-clad steel.

[0025] The substrate may include multiple layers, with coils and traces defined in different layers to optimize electrical performance and mechanical flexibility. Vias can be used to achieve electrical connections between traces and coils across different layers.

[0026] The substrate may include a sensing region located at its first end. An array of coils may be defined within the sensing region and arranged laterally along the sensing region. In this context, the coils may be defined by patterned conductive traces formed within the substrate in one or more loops or spirals extending across one or more layers. Laterally arranged coils mean that the coils are arranged along the length of the sensing region (e.g., Figure 2 SR shown in the embodiment L The coils are arranged side-by-side (in the direction of the first end edge of the substrate) and, in some embodiments, at least partially overlap. Compared to a longitudinally staggered arrangement of coils, this lateral and partially overlapping arrangement allows the sensing area to be positioned relative to its length (e.g., SR). L The width of the substrate remains narrower than the width of the entire lateral width of the substrate (e.g., the width defined along the direction of the first end edge of the substrate). Figure 2 The narrower SR shown in the embodiment W This allows the sensing elements to be concentrated in a compact area.

[0027] By arranging the coils within a relatively narrow sensing region, the circuitry can more easily bend simultaneously along a first direction (e.g., parallel to the scanning direction) and a second direction orthogonal to the longitudinal axis of the substrate. For example, as further described below, a narrow sensing region coupled with a longitudinal slot defined on the substrate can reduce the resistance to simultaneous bending of the sensing region along multiple transverse axes, allowing the sensing region to conform to surfaces that bend in multiple directions. This flexibility enables the circuitry to adapt to complex test surface and ensures that the sensing region, including the coil array, remains in close contact (e.g., against) the test surface, thereby improving detection coverage and detection sensitivity.

[0028] In some embodiments, the coil array may include alternating first and second coils, wherein portions of the first coils overlap portions of the second coils. This arrangement can be achieved by placing a portion of the first coil on one or more layers of a substrate, and placing the overlapping portions of the second coils on one or more other layers of the substrate. For example, the coils may be formed as coil traces, with the coil traces of the first coil defining a first subset of the sensing region layer, and the coil traces of the second coil defining a second subset of the sensing region layer.

[0029] In some embodiments, the first coil and the second coil may be collinearly aligned along the sensing region. For example, the coil array including the first coil may be arranged along a straight line or a substantially straight line, while the second coil may be arranged along the same straight line or a substantially straight line as the first coil. This linear arrangement can maximize the coil coverage within the sensing region while maintaining a narrow width (e.g., compared to a nonlinear arrangement with an interlaced or offset pattern, which may require a wider sensing region and reduce flexibility).

[0030] In some implementations, a first subset of the sensing region layer may include two layers, and a second subset of the sensing region layer may include two layers located between the two layers of the first subset. For example, a first coil may be formed in the first and fourth layers of the sensing region (e.g., the top and bottom layers), while a second coil may be formed in the second and third layers (e.g., the middle layer). This vertical offset allows the first and second coils to overlap within the sensing region without increasing the overall width of the sensing region. Furthermore, arranging the first coil in the first and fourth layers and the second coil in the second and third layers balances the average lift-off effect of each coil, resulting in more uniform sensitivity across the entire array. Therefore, this overlapping arrangement can improve coil density and detection sensitivity while maintaining a compact sensing region.

[0031] In addition to the sensing region, the substrate may further include: a wiring region located at a second end opposite to the first end; and an intermediate region extending between the sensing region and the wiring region. Conductive traces may be defined within the intermediate region and the wiring region, and extend longitudinally along the intermediate region and the wiring region, for electrically coupling the coil array to the probe connector of the ECA probe. The traces may be patterned conductive lines laid along the substrate, with each coil connected to the probe connector via a pair of dedicated traces. Vias may be used to couple traces and / or coils between layers.

[0032] Longitudinal slots can be defined in the middle region of the substrate, between at least some conductive traces. The longitudinal slots can mechanically decouple the curvature of the sensing area from the wiring area. The slots can be elongated openings extending parallel to the length of the substrate and can be arranged in a repeating pattern laterally along the middle region. In some embodiments, the slots can extend through all substrate layers, thereby forming a continuous gap that completely penetrates the substrate thickness. In other embodiments, the slots can penetrate only a subset of the substrate layers. The shape of the slots can include elongated portions with arcuate ends, wherein the width of the arcuate ends is greater than that of the middle portion, which helps to disperse mechanical stress and prevent tearing at the edges of the slots.

[0033] By incorporating the aforementioned longitudinal slots, the substrate can be divided into multiple mechanically independent segments, allowing the sensing area to bend more freely without transmitting mechanical stress to the wiring area. This mechanical decoupling means that when the sensing area presses against a contoured workpiece, the suppression or restriction effect of the wiring area on the bending of the sensing area is minimized. Consequently, the sensing area can maintain close contact with complex surfaces, while the wiring area remains largely unaffected by deformation, reducing the risk of circuit damage during testing and improving the reliability of the circuitry.

[0034] The substrate can be elongated, with its (lateral) width being relatively smaller than its (vertical) length. A sensing area can be positioned at a first end, a wiring area at a second end, and an intermediate area extending between the two. This geometry allows the sensing area to be concentrated at the edge of the circuitry, while the wiring area provides space for electrical connections and integration with probe connectors.

[0035] The sensing region may have a width extending longitudinally from the edge of a first end of the substrate toward a central region and a length extending along the edge of the first end. In some embodiments, the length of the sensing region is at least 5 times its width, for example, at least 8 times, at least 12 times, at least 16 times, or at least 32 times. The aspect ratio of the width to the length of the sensing region may be in the range of 1:5 to 1:32, for example, in the range of 1:8 to 1:32. For example, the width of the sensing region may be in the range of 1-5 mm, and the length may be in the range of 5-25 mm (e.g., 1 mm wide and 5 mm long, 3 mm wide and 15 mm long, 5 mm wide and 25 mm long). A width smaller than the length of the sensing region allows it to bend more effectively in multiple orthogonal dimensions.

[0036] The intermediate region may have a width similar to or equal to the length of the longitudinal slot and may extend longitudinally from the sensing region to the wiring region. In a particular embodiment, the width of the intermediate region is greater than one-third of the length of the sensing region (i.e., IRw > SR). L / 3). For example, if the length of the sensing area is in the range of 5-25 mm and the width of the middle area can be in the range of 2-10 mm (e.g., sensing area length 5 mm and middle area width 2 mm, sensing area length 18 mm and middle area width 10 mm, or sensing area length 25 mm and middle area width 10 mm), the length of the longitudinal slot can be greater than one-third of the sensing area length (e.g., slot length > SR). L / 3). For example, if the length of the sensing area is in the range of 5-25 mm, the length of the longitudinal slot can be in the range of about 2-10 mm (e.g., sensing area length of 5 mm and longitudinal slot length of 2 mm, sensing area length of 18 mm and longitudinal slot length of 10 mm, or sensing area length of 25 mm and longitudinal slot length of 10 mm).

[0037] In some embodiments, the width of the intermediate region is at least three times the width of the sensing region. For example, if the width of the sensing region is in the range of 1-5 mm, the width of the intermediate region can be in the range of 3-15 mm (e.g., sensing region width 1 mm and intermediate region width 3 mm, sensing region width 3 mm and intermediate region width 10 mm, sensing region width 5 mm and intermediate region width 15 mm). The length of the longitudinal slot can be at least three times the width of the sensing region. For example, if the width of the sensing region is in the range of 1-5 mm, the length of the slot can be in the range of 3-15 mm (e.g., sensing region width 1 mm and slot length 3 mm, sensing region width 3 mm and slot length 10 mm, sensing region width 5 mm and slot length 15 mm).

[0038] In some embodiments, the substrate may include a structure in which a sensing region is located at or near the longitudinal midpoint of the substrate, and intermediate regions extend outward from opposite sides of the sensing region (e.g., in a mirror or near-mirror arrangement). Each intermediate region may include a corresponding set of conductive traces and longitudinal slots, such that both sides of the sensing region possess the mechanical decoupling characteristics and bending properties described herein. This arrangement allows the circuitry to bend or fit together in two lateral directions with similar stiffness and deformation response (e.g., suitable for applications requiring bidirectional scanning or where the orientation of the probe relative to the test object may change). The width and length of the sensing region, as well as the geometry and / or length of the longitudinal slots in each intermediate region, may be similar to the dimensions described herein.

[0039] In some embodiments, the number of layers in the intermediate region of the substrate may be less than the number of layers in the sensing region. For example, the sensing region may have four layers to accommodate overlapping coils, while the intermediate region may have only two layers to increase flexibility and reduce material usage. Pairs of conductive traces corresponding to each coil may be routed back and forth along the corresponding layers of the two intermediate regions. The transition in the number of layers between the intermediate region and the sensing region may be achieved using fabrication processes such as selective lamination (i.e., stacking additional layers in the sensing region) or stepped wiring.

[0040] In some embodiments, each coil in the array can be coupled to a pair of conductive traces, each pair of traces extending in an overlapping manner along adjacent layers in the intermediate region. For example, the transmit and return traces for a particular coil can be arranged on two adjacent layers, facing each other vertically, to minimize loop area and reduce electromagnetic interference. Minimizing loop area reduces the generation of unwanted eddy currents and crosstalk between channels.

[0041] In some embodiments, no more than two pairs of conductive traces may be positioned between adjacent longitudinal slots. The traces may lie between the longitudinal slots, each providing mechanical isolation. Providing longitudinal slots between each trace improves mechanical decoupling. However, adding more longitudinal slots increases manufacturing difficulty and complexity. Limiting the number of traces between longitudinal slots to no more than two pairs allows for good mechanical decoupling while maintaining sufficient electrical connectivity. In some embodiments, only one pair of traces may be placed between each longitudinal slot, further enhancing flexibility. In some embodiments, more than two pairs of traces may also be placed between each longitudinal slot.

[0042] In some embodiments, advanced printed circuit board (PCB) manufacturing processes can be used to fabricate the circuit devices, such as photolithography, chemical or plasma etching, and multilayer lamination. The substrate can be fabricated layer by layer, each layer being patterned to define the desired coil and trace geometry. Conductive materials can be deposited using processes such as electroplating or sputtering, and then etched to form precise coil and trace patterns. Longitudinal slots can be formed using high-precision laser cutting and / or mechanical stamping processes. The slots can be formed after lamination to ensure they penetrate the required number of substrate layers. Additional steps, such as drilling and electroplating, can be used to form vias for interlayer electrical connections.

[0043] The circuitry can be integrated into the ECA probe assembly, where the sensing area is positioned at the probe tip, and the wiring area connects to the probe connector. An elastic backing material, such as foam or an elastomer, can be provided to press the sensing area against the test piece and ensure a close contact. The elastic backing can be designed to distribute pressure evenly along the length and / or width of the sensing area when pressed against the test surface, ensuring a tight fit even if the surface has curvature in multiple directions. The elastic backing can be made of materials such as silicone rubber, polyurethane, or other elastomers, which possess the property of returning to their original shape after compression deformation. This elastic deformation and recovery characteristic allows the backing to maintain a continuous and uniform contact force in the sensing area during use, thereby reducing lift-off effect deviations and improving detection reliability. The backing can be located directly on the back of the sensing area within the probe assembly and can be adhesively or mechanically fixed to the substrate or probe housing.

[0044] During operation, the acquisition device, coupled to the circuitry via a probe, executes a timing coil excitation sequence, selectively energizing the coils and acquiring the corresponding eddy current signals. A multiplexer (MUX) can be used to select which coil is energized and read at a given time. The MUX can be incorporated into the circuitry itself, for example, within a wiring area at the second end of the circuitry, or in other embodiments, into the probe assembly. The acquired data can be processed by the acquisition device to detect defects, cracks, or other anomalies in the test piece. The flexible decoupling design of the circuitry enables reliable inspection of surfaces with complex geometries.

[0045] Figure 2 A circuit arrangement 200 for an ECA probe is shown, while Figure 3 yes Figure 2 A partial enlarged view of the circuit device. Figure 2 and Figure 3 All aspects of the circuit arrangement can be implemented in any embodiment of the circuit arrangement and / or ECA probe described herein, and vice versa. The circuit arrangement may include a substrate 206 extending longitudinally from a first end 202 toward a second end 204. The first end may be located near one edge of the substrate, while the second end may be located near the opposite edge of the substrate.

[0046] The substrate may be elongated, with its length greater than its width, and may provide electrical and mechanical support for the various components of the circuit device. At a first end, the substrate may include a sensing region 208. At a second end, the substrate may include a wiring region 210. An intermediate region 212 may extend longitudinally between the sensing region and the wiring region.

[0047] The coil array 214 can be arranged laterally along the sensing region. The coils can be formed from a patterned conductive material within the substrate, with each coil positioned side-by-side and overlapping at least one adjacent coil portion. The coils can be defined within one or more layers of the substrate for a compact arrangement. In some embodiments, the coil array can include alternating first coils 220 and second coils 222, portions of the first coils overlapping portions of the second coils. This overlapping arrangement can be achieved by forming the first coils on a subset of the substrate and the second coils on another subset of the substrate (e.g., forming the first coils on a subset of the sensing region layers and the second coils on another subset of the sensing region layers). This configuration can improve coil density and detection sensitivity while maintaining a narrow width of the sensing region.

[0048] Conductive traces 216 can extend longitudinally along the intermediate region and wiring region. These conductive traces can electrically couple each coil in the array to the probe connector and / or multiplexer of the probe, thereby enabling signal transmission between the coil and external electronic equipment. Each coil can correspond to a pair of traces to electrically couple the coil to the probe, and the two traces in each pair can be arranged on adjacent layers of the substrate and can be vertically overlapped to minimize the loop area, thereby reducing electromagnetic interference and crosstalk. In this context, "loop area" refers to the effective electromagnetic loop area formed by the conductive traces associated with each coil for transmission and return, rather than the physical winding of the coil itself. The loop area can represent the size of the current-carrying loop formed by the trace pair. A larger loop area increases the magnetic flux linkage with the external magnetic field, making it more susceptible to induced noise, parasitic eddy currents, and inter-channel crosstalk. By arranging the traces in adjacent layers so that they vertically overlap, the effective loop area of ​​each pair of traces can be reduced, thereby improving signal integrity and reducing electromagnetic interference.

[0049] To enhance mechanical flexibility, a longitudinal slot 218 can be defined within the central region, positioned between at least some conductive traces. The slot can extend parallel to the length of the substrate and mechanically decouple the bending of the sensing area from the wiring area. This decoupling allows the sensing area to flex independently of the wiring area, reducing the transmission of mechanical stress and minimizing the risk of circuit damage during use on complex surfaces. The slot can include an arcuate edge 228 at its ends, the width of which is greater than the elongated central portion of the slot. This geometry helps to disperse mechanical stress and prevents the substrate from tearing or cracking at the slot ends.

[0050] The edge 224 of the substrate can define the boundary of the first end, adjacent to the sensing area. Vias 226 can be used throughout the substrate to enable electrical connections between traces and coils between different layers. This design enables complex wiring and overlapping coil arrangements without increasing the overall width of the sensing area.

[0051] Width IR of the middle region W It can be larger than the width of the sensing area SR W For example, at least 3, 4, or 5 times its original value. The width of the sensing area SR W The length SR of the sensing area extending along the edge of the first end can be relative to the length of the sensing area. L Narrower. For example, the length SR of the sensing area. L It can be at least 5, 6, or 7 times its width. In some embodiments, the width IR of the middle region is... W It can be greater than the length SR of the sensing area. L one-third (i.e., IR) W >SR L / 3).

[0052] Figure 3 It is a magnified view of a part of the circuit device, focusing on the sensing area and the arrangement of the coil array. Figure 3 The diagram illustrates the lateral arrangement of the coils, with the first and second coils positioned alternately and collinearly along the sensing area. Vias for interlayer connections are also shown.

[0053] exist Figure 2 and Figure 3 In various embodiments of the circuit device, a narrow (e.g., 1.6 mm wide) active region (i.e., sensing region) comprises overlapping eddy current coils fabricated using a multilayer PCB structure. In this example, the first coil may be formed using conductors from the second and third layers of the substrate, while the second coil may be formed using conductors from the first and fourth layers of the substrate. A series of cuts, such as slots, holes, grooves, or notches (extending 14 mm in this example) (e.g., longitudinal grooves), may be included in the flexible PCB assembly to decouple the bending of the sensitive coil region (e.g., sensing region) from the rest of the flexible circuit assembly (e.g., wiring areas), particularly areas located at opposite ends of the circuit assembly, away from the sensitive coil region. The areas at the ends of each cut may be designed with an arc shape to reduce the risk of mechanical stress concentration at that location during deformation. Such features can suppress or prevent tearing, delamination, or other mechanical damage to the sensor assembly.

[0054] Figure 4 It is a circuit device 400 for eddy current array (ECA) probes, comprising four substrate layers. Figure 4 It shows four substrate layers stacked on top of each other, and Figures 5 to 8 The different layers of the four layers are shown respectively. Figure 4 The circuit device is similar to in many ways. Figure 2 The circuit devices are similar. This article focuses on... Figure 4 Any aspect disclosed in the circuit device can be incorporated. Figure 2 In embodiments of the circuit device, the reverse is also true. Figure 4 The circuit arrangement includes a sensing region 408, an intermediate region 412, and a coil array 414. The array includes a first coil 420 and a second coil 422. The circuit arrangement also includes conductive traces 416 and longitudinal slots 418. Vias 426 are included for coupling between interlayer coil portions and / or conductive traces. Although... Figure 4 The non-limiting embodiment illustrates a four-layer arrangement, but this configuration is not restrictive, and other embodiments may employ more or fewer substrate layers. For example, a simpler structure may use two or three substrate layers, while embodiments requiring higher wiring density, shielding performance, or mechanical tuning may use five, six, or more substrate layers. Unless otherwise explicitly stated, the specific number of layers used can be adjusted according to design requirements and is not limiting.

[0055] Figure 5 yes Figure 4 The first layer 432 of the circuit device. For example... Figure 5 As shown, a multi-turn winding of a first coil is defined in the first layer. Vias are used to connect the winding of the first coil in the first layer to... Figure 8 The fourth layer is shown to be coupled to the winding of the first coil. Conductive traces are defined in the first layer and coupled to the winding of the first coil defined in the first layer. The conductive traces in the first layer also extend to vias for connection to… Figure 7 The winding coupling of the second coil defined in the third layer shown.

[0056] Figure 6 yes Figure 4 The second layer 434 of the circuit device. For example... Figure 6 As shown, a multi-turn winding of a second coil is defined in the second layer. Vias are used to connect the winding of the second coil in the second layer to... Figure 7 The winding of the second coil is coupled within the third layer shown. Conductive traces are defined in the second layer and coupled to the winding of the second coil defined in the second layer. The conductive traces in the second layer also extend to vias for connection to… Figure 8 The winding coupling of the first coil defined in the fourth layer shown.

[0057] Figure 7 yes Figure 4 The third layer 436 of the circuit device. For example... Figure 7As shown, a multi-turn winding of a second coil is defined in the third layer. The winding of the second coil defined in the third layer is coupled to the corresponding winding of the second coil defined in the second layer at a via. The other end of the winding of the second coil defined in the third layer is coupled to the conductive trace in the first layer at a via.

[0058] Figure 8 yes Figure 4 The fourth layer 438 of the circuit device. For example... Figure 8 As shown, a multi-turn winding of the first coil is defined in the fourth layer. The winding of the second coil defined in the fourth layer is coupled to the corresponding winding of the first coil defined in the first layer at a via. The other end of the winding of the first coil defined in the fourth layer is coupled to a conductive trace in the second layer at a via.

[0059] Therefore, as Figures 4 to 8 As shown, a first coil is defined in a first layer and a fourth layer, while the traces for coupling the first coil to the probe are defined in a first layer and a second layer. Furthermore, each pair of traces corresponding to the first coil overlaps with each other as they extend along their respective first and second layers of the substrate. A second coil is defined in a second layer and a third layer, while the traces for coupling the second coil to the probe are defined in a first layer and a second layer. Furthermore, each pair of traces corresponding to the second coil overlaps with each other as they extend along their respective first and second layers of the substrate.

[0060] Figure 9 Experimental test data 900 is shown, including an impedance plane plot 902 and a corresponding imaging result 904, which illustrates a defect indication 906 obtained using an ECA sensing component according to an embodiment of this disclosure. In this example, the test piece is a turbine blade, whose surface profile exhibits curvature in multiple directions, posing a challenge for detection by conventional probes. The impedance plane plot demonstrates the response of the ECA probe as it scans the test piece, with defect indications appearing as significant deviations or features in the impedance data. The corresponding imaging result provides the spatial distribution of the location and size of the defects on the test piece.

[0061] Figure 9 The defect indications shown demonstrate the improved detection sensitivity and coverage provided by the ECA sensing component described in this disclosure. In contrast, conventional eddy current array devices may struggle to maintain adequate contact with surfaces that have curvature in multiple directions, causing portions of the sensing area to detach from the surface and resulting in decreased detection sensitivity. Therefore, Figure 9 The defects shown in the image may be missed when using conventional probes.

[0062] Figure 10This is a schematic diagram of an ECA sensing component 1000. The sensing component may include a test instrument 1040 (i.e., a data acquisition device), such as a handheld or portable component. The test instrument may, for example, be electrically coupled to a probe component 1050 using a multi-conductor interconnect 1030. The probe component may include one or more transducers, such as an EC transducer array 1052 comprising corresponding eddy current sensors 1054A to 1054N. The transducer array may have a linear or arcuate profile and may also comprise an array of elements extending along multiple axes. In some embodiments, the probe component may include, or be coupled to, embodiments of the circuitry disclosed herein (e.g., including an array of coils as an eddy current sensor).

[0063] Modular probe assemblies can be employed, allowing the test instrument to be used with a variety of different probe assemblies. Typically, the transducer array may include an EC coil located on or within a substrate. The EC coil is electromagnetically coupled to the target part 1058 (e.g., the sample under test or "test object"). The test instrument may include digital and analog circuitry, such as front-end circuitry, which includes one or more transmit signal chains, receive signal chains, or switching circuitry (e.g., transmit / receive switching circuitry). The transmit signal chains may include amplification and filtering circuitry for generating transmit pulses and transmitting them to the probe assemblies via interconnects. For example, defects 1060 associated with the target part can be detected by monitoring the impedance or other electrical characteristics associated with each sensor in the transducer array.

[0064] although Figure 10 A single probe assembly and a single transducer array are shown, but other configurations are also possible, such as multiple probe assemblies connected to the same test instrument, or multiple transducer arrays used for a single probe assembly. Similarly, multiple test instruments can be used to collaboratively execute test procedures, for example, in response to an overall test plan developed by a single test instrument, or by another remote system (such as computing device 1008) or a general-purpose computing device (laptop 1032, tablet, smartphone, or desktop computer).

[0065] The front-end circuitry 1022 may be coupled to and controlled by one or more processor circuits, such as the processor circuitry 1002 built into the test instrument. The processor circuitry may be coupled to memory circuitry 1004, for example, for executing instructions to cause the test instrument to perform one or more EC tests, process or store data related to the EC tests, or perform other techniques shown and described herein. The test instrument may, for example, use a wired or wireless communication interface 1020 to communicate with other parts of the system.

[0066] The testing instrument may include: a display 1010 for displaying configuration information or test results; and an input device 1012, which may include, for example, one or more of a keyboard, trackball, function keys or soft keys, mouse interface, touch screen, touch or pen, for receiving operator instructions, configuration information or query responses.

[0067] Figure 11 An ECA probe assembly 1100 is shown. This probe assembly may include a circuit arrangement 1102 coupled to a probe 1104. The probe may include a connector 1106 for electrically coupling the probe to a data acquisition device. The probe may also include a resilient backing 1108. The circuit arrangement may employ any of the embodiments disclosed herein, including various variations in substrate material, coil arrangement, trace wiring, and slot construction.

[0068] exist Figure 11 In this design, the resilient backing is cylindrical and attached to the probe's test surface. This cylindrical shape allows the circuitry (e.g., the sensing area) to bend laterally, enabling the sensing area to conform to the contour of the test piece. The resilient backing can also allow the circuitry to bend longitudinally to conform to the test piece surface, which may have curvature in multiple directions. In other embodiments, depending on the desired contact profile and flexibility, the resilient backing can take other shapes, such as arcuate, saddle-shaped, wedge-shaped, dome-shaped, crescent-shaped, annular, or segmented structures. The backing can be made of materials such as silicone rubber, polyurethane, foam, or other elastomers, which are capable of returning to their original shape after deformation while providing pressure against the circuitry to conform to the test piece surface.

[0069] In some embodiments, the elastic backing may not be required. Figure 11 As shown, it is positioned directly below the probe. For example, the backing can extend outward from the probe along with the circuitry, allowing the circuitry and backing to move and press more freely into the contour of the test piece. This arrangement can accommodate the testing of complex or irregular geometric surfaces, and during non-destructive testing, the circuitry and backing can be manipulated in tandem to achieve optimal contact and coverage.

[0070] Figure 12 Image 1200 shows a printed circuit board of an ECA probe, which has been manually pressed and bent into a complex area of ​​the test piece. This image demonstrates that the printed circuit board, as an embodiment of the circuitry disclosed herein, can fit snugly against the surface of the test piece, which exhibits curvature in multiple directions. This ability to adapt to complex surfaces and maintain contact fully demonstrates the effectiveness of this flexible circuitry design in non-destructive testing applications.

[0071] The component construction shown and described herein and in the accompanying figures facilitates non-destructive testing of structures with curved profiles or shapes, such as structures with large curvature in two directions simultaneously. Examples of structures with such shapes include turbine blades, such as the crown region near the blade root of a high-pressure turbine blade used in a gas turbine engine.

[0072] Each of the non-limiting aspects in the foregoing and accompanying figures may be practiced individually or in combination with one or more other aspects or topics described herein in various permutations or combinations.

[0073] The above detailed description includes references to the accompanying drawings, which form part of the detailed description. The drawings illustrate specific embodiments in which the invention can be implemented by way of example. These embodiments are also collectively referred to herein as "examples". Such examples may include elements other than those illustrated or described. However, the inventors also contemplate examples that provide only illustrated or described elements. Furthermore, the inventors contemplate examples that, for a particular example (or one or more aspects thereof), or for other examples shown or described herein (or one or more aspects thereof), employ any combination or arrangement of illustrated or described elements (or one or more aspects thereof).

[0074] In the event of any conflict between the usage in this article and any other reference incorporated by way of citation, the usage in this article shall prevail.

[0075] In this document, consistent with common usage in patent literature, the terms "a" or "an" are used to indicate the inclusion of one or more, regardless of any scenario or usage of "at least one" or "one or more." In this document, the term "or" is used to indicate a non-exclusive "or," so unless otherwise stated, "A or B" includes "A but not B," "B but not A," and "A and B." In this document, the terms "comprising" and "wherein" are used as common English equivalents of the corresponding terms "comprising" and "in this scheme." Furthermore, in the appended claims, the terms "comprising" and "comprising" are open-ended expressions, meaning that a system, apparatus, product, composition, formulation, or method that includes other elements besides those listed after the term is still within the scope of protection of that claim. Additionally, in the appended claims, the terms "first," "second," and "third," etc., are used merely as labels and are not intended to impose numerical requirements on their objects.

[0076] The above description is intended to be illustrative and not restrictive. For example, the above examples (or one or more aspects thereof) can be used in combination with each other. Other embodiments can also be adopted by those skilled in the art after reading the above description. The purpose of providing the abstract is to enable the reader to quickly identify the core content of the technical disclosure. When submitting the abstract, it should be understood that it is not intended to interpret or limit the scope or meaning of the claims. Furthermore, in the above detailed description, various features can be combined together to simplify the disclosure. This should not be construed as meaning that unclaimed disclosed features are essential to any claim. Rather, the subject matter of the invention may be fewer than all the features of a particular disclosed embodiment. Therefore, the appended claims are incorporated herein by way of example or embodiment, each claim existing independently as a separate embodiment, and these embodiments are contemplated to be combined with each other in various combinations or arrangements.

Claims

1. A circuit arrangement for an ECA probe, wherein the ECA probe is an eddy current array probe, the arrangement comprising: A substrate, the substrate comprising: The sensing area is located at the first end of the substrate; A wiring region located at a second end of the substrate opposite to the first end; and The intermediate region extends between the sensing region and the wiring region; A coil array, the coil array being defined in the sensing region and arranged laterally along the sensing region; A conductive trace, defined and extending longitudinally along the intermediate region and the wiring region, for coupling the coil array to the ECA probe; and A longitudinal slot, defined in the middle region of the substrate and located between at least some of the conductive traces, is used to mechanically decouple the bending of the sensing region from the wiring region.

2. The apparatus according to claim 1, wherein, The coil array includes an alternating arrangement of a first coil and a second coil, wherein portions of the first coil and portions of the second coil overlap.

3. The apparatus according to claim 2, wherein, The longitudinal slots and the conductive traces are defined by a laterally alternating arrangement across the intermediate region.

4. The apparatus according to claim 2, wherein, The first coil and the second coil are collinearly aligned.

5. The apparatus according to claim 2, wherein: The sensing area of ​​the substrate includes multiple sensing area layers, and the coil includes coil traces; The coil traces of the first coil are defined in a first subset of the sensing region layer; and The coil traces of the second coil are defined in a second subset of the sensing region layer.

6. The apparatus according to claim 5, wherein, The first subset of the sensing region layer comprises two layers, while the second subset of the sensing region layer comprises two layers located between the two layers of the first subset.

7. The apparatus according to claim 5, wherein, The number of layers in the middle region of the substrate is less than the number of layers in the sensing region.

8. The apparatus according to claim 1, wherein, Each coil in the array is coupled to a pair of conductive traces, and the pair of conductive traces extend in an overlapping manner along adjacent layers of the intermediate region.

9. The apparatus according to claim 8, wherein, The number of conductive traces positioned between adjacent longitudinal slots shall not exceed two pairs.

10. The apparatus according to claim 1, wherein, The sensing area includes: The width of the sensing area extends longitudinally from the edge of the first end of the substrate toward the middle region; and The sensing region has a length that extends along the edge of the first end of the substrate, and the length of the sensing region is at least 5 times the width of the sensing region.

11. The apparatus according to claim 1, wherein, The intermediate region includes an intermediate width, which is equal to the length of the longitudinal slot and extends longitudinally from the sensing region to the wiring region. The width of the intermediate region is at least three times the width of the sensing region.

12. The apparatus according to claim 1, wherein, The longitudinal slot includes: Arc-shaped ends; and The elongated portion is located between the arc-shaped ends, and the width of the arc-shaped ends is greater than the width of the middle portion of the elongated portion.

13. An ECA sensing component, wherein the ECA sensing component is an eddy current array sensing component, the ECA sensing component comprising: The probe includes: A circuit board comprising a coil array; and A resilient backing that can be positioned against the surface of the circuit board; and A data acquisition device is operably coupled to the coil array to realize a preset timing coil excitation sequence and acquire the corresponding eddy current signal; wherein, the circuit board further includes: A substrate, the substrate comprising: A sensing region located at a first end of the substrate, wherein the coil array is defined in the sensing region and arranged laterally along the sensing region; A wiring region located at a second end of the substrate opposite to the first end; and The intermediate region extends between the sensing region and the wiring region; A conductive trace, defined within and extending longitudinally along the intermediate region and the wiring region, is used to couple the coil array to the acquisition device; and A longitudinal slot, defined in the middle region of the substrate, is located between at least some of the conductive traces, wherein the elastic backing is configured to bend the sensing area of ​​the substrate to conform to the contour of the test object.

14. The ECA sensing component according to claim 13, wherein, The coil array includes an alternating arrangement of a first coil and a second coil, with portions of the first coil overlapping portions of the second coil, and the first coil and the second coil being collinearly aligned.

15. The ECA sensing component according to claim 14, wherein, The longitudinal slots and the conductive traces are defined in a laterally alternating manner across the intermediate region.

16. The ECA sensing component according to claim 13, wherein: The sensing area of ​​the substrate includes multiple sensing area layers; The coil includes coil traces, and the coil traces of the first coil are defined in a first subset of the sensing region layer; and The coil traces of the second coil are defined in a second subset of the sensing region layer.

17. The ECA sensing component of claim 16, wherein, The first subset of the sensing region layer comprises two layers, while the second subset of the sensing region layer comprises two layers located between the two layers of the first subset.

18. The ECA sensing component according to claim 16, wherein, The number of layers in the middle region of the substrate is less than the number of layers in the sensing region.

19. The ECA sensing component according to claim 13, wherein, Each coil in the array is coupled to a pair of conductive traces, and the pair of conductive traces extend in an overlapping manner along adjacent layers of the intermediate region.

20. The ECA sensing component according to claim 13, wherein, The sensing area includes: The width of the sensing area extends longitudinally from the edge of the first end of the substrate toward the middle region; and The sensing region length extends along the edge of the first end of the substrate, wherein the intermediate region includes an intermediate width equal to the length of the longitudinal slot and extending longitudinally from the sensing region to the wiring region, and the width of the intermediate region is greater than one-third of the length of the sensing region.

21. A circuit arrangement for an ECA probe, wherein the ECA probe is an eddy current array probe, the arrangement comprising: A substrate, the substrate comprising: The sensing area is located at the first end of the substrate; A wiring region located at a second end of the substrate opposite to the first end; and The intermediate region extends between the sensing region and the wiring region; A coil array defined in the sensing region; A conductive trace, defined and extending along the intermediate region and the wiring region, for coupling the coil array to a probe connector of the ECA probe; and A longitudinal slot is defined in the middle region of the substrate, wherein the elastic backing of the ECA probe is configured to bend the sensing area of ​​the substrate to conform to the contour of the test object.

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