Automated control of electrical connection joining process

Abstract

To establish electrical connection to a flexible circuit strip of a catheter.SOLUTION: There is provided a method of electrically connecting a wire to a connection pad of a flexible circuit strip by using a heat joining tool. The flexible circuit strip includes a polymer body, a plurality of electrodes, a plurality of connection pads, and a plurality of conductive traces, a trace connecting each of the plurality of electrodes to a connection pad of the plurality of connection pads. The method includes: positioning the joining tool in proximity to a connection pad of the plurality of connection pads and a wire to be connected to the connection pad; activating the joining tool to heat a tip of the joining tool and electrically connecting the wire to the connection pad; monitoring, during the activating, a resistance between the joining tool and an electrode electrically connected to the connection pad, resistance indicative of temperature of the flexible circuit strip; and controlling the activating to maintain the resistance below an upper threshold associated with the flexible circuit strip reaching a damaging temperature.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] (Related Applications) This application claims priority from U.S. Provisional Patent Application No. 63 / 603,144, filed on November 28, 2023, the content of which is incorporated herein by reference as if fully set forth herein.

[0002] (Field of the Invention) In some embodiments, the present disclosure relates to catheter manufacturing, and more specifically, but not limited thereto, to establishing electrical connections to flexible circuit strips of catheters.

Background Art

[0003] A wide range of medical procedures involve placing a probe, such as a catheter, inside a patient's body. Electrode catheters have been commonly used in the medical industry for many years. They are used to stimulate, map, and ablate sites of abnormal electrical activity in the heart.

[0004] A catheter having a plurality of electrodes attached to an expandable distal end assembly of the catheter can be used to map and / or ablate the wall cavity of a patient's organ, such as a heart chamber. The expandable distal end assembly is connected to the distal end of a catheter shaft for insertion into the cavity. The expandable distal end assembly can be shaped in the form of a balloon, a basket, and / or another type of cage and can include a plurality of electrodes configured to sense and / or deliver a treatment signal.

Brief Description of the Drawings

[0005] To better understand the subject matter disclosed herein and to illustrate how the subject matter can actually be practiced, embodiments will be described by way of mere non-limiting examples with reference to the accompanying drawings here.

Figure 1A

Figure 1B

Figure 2

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Figure 5C

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Figure 5E

[0006] In some embodiments, by way of non-limiting example, like elements are referenced using like numerals.

DETAILED DESCRIPTION

[0007] In some embodiments, the present disclosure relates to catheter manufacturing, and more specifically, but not limited thereto, to establishing electrical connections to the flexible circuit strips of catheters.

[0008] Summary Some catheters, such as basket catheters, can have many (e.g., 30 to 100) electrodes mounted on a plurality of splines of the basket, and the basket is coupled to a connector at the proximal end of the shaft via the catheter shaft. In some embodiments, the electrodes can be housed by a plurality of flexible printed circuit boards (PCBs), each of which is mounted on a spline of the basket. Both the flexible PCB on the spline (also referred to herein as a “flexible circuit strip”) and the PCB of the connector have pads and a plurality of wires (e.g., wires for each electrode extending through the shaft) to provide an electrical connection. The distal end of each wire is coupled to a predetermined pad on the spline, and the proximal end of each wire is coupled to a corresponding pad in the connector to exchange electrical signals between the electrodes and a control console, such as the catheter's PIU (patient interface unit), via the shaft. Due to the limited area on the spline, the pads need to cover a small area. For example, the pad size (e.g., pad surface area) can be in the order of tens of square micrometers (also referred to herein as square microns) for each pad on the printed circuit board, resulting in a potentially time-consuming and / or costly bonding process between the wires and their respective pads. The pads can also be placed in close proximity to each other. For example, the spacing between pads is less than the length and / or width of the pads, and / or here, the distance between adjacent pads is less than 0.1 to 0.5 mm. The pads can densely occupy the area on the flexible circuit strip. Here, for example, the percentage of the surface area occupied by the pads is 20 to 50%.

[0009] In manufacturing, for example, the (e.g., sequential) thermal bonding (e.g., soldering or welding) of many wires to many pads of a flexible circuit strip, which involves repeated heating of the wires and pads, can increase the temperature of the flexible circuit strip to a level where, for example, the material of the strip (e.g., the polymer body of the flexible circuit strip) is damaged. For example, in connection with the repeated heating for connecting a plurality of pads, the heat applied to connect a wire to one pad can lead to undesired heating of another adjacent pad to which the wire is already connected, for example, further affecting the polymer body around the previously connected and heated pad and / or potentially degrading the quality of the already established connection.

[0010] In broad aspects, some embodiments of the present disclosure relate to monitoring the resistance between a bonding tool for connecting a wire to a pad and an electrode corresponding to the pad. The resistance and / or the change in resistance over time can potentially provide an indication of the temperature of the flexible polymer strip, where, for example, an increase in resistance generally indicates an increase in temperature. For example, the detected resistance includes the resistance of the pad, the electrode, and the trace connecting the pad and the electrode, each of which can be affected by temperature.

[0011] In certain aspects, some embodiments of the present disclosure relate to establishing an electrical connection to a pad of a flexible circuit strip using a bonding tool, where the heating of the bonding tool to form the connection is controlled using the detected resistance between the bonding tool and an electrode connected to the pad.

[0012] In some embodiments, the flexible circuit strip includes a heat-sensitive material (e.g., includes a polymer). Heat sensitivity can manifest as deformation and / or chemical changes to the material due to exposure to a temperature above a threshold and / or an elevated temperature for a duration longer than a threshold.

[0013] The detected resistance potentially indicates the temperature of the polymer body of the flexible polymer strip, and the polymer body may tend to increase in temperature during the connection process, and this increase is related to the heat insulation property of the polymer material, for example, compared to electrical components.

[0014] In some embodiments, the flexible circuit strip includes a plurality of pads, and establishing the connection is, for example, a plurality of connections to each of the plurality of pads sequentially and / or by a single bonding tool.

[0015] In some embodiments, the pads are filled adjacent to and / or disposed directly on a heat-sensitive material, such as a polymer body. In some embodiments, the electrical circuit connected to the pads (e.g., the traces and electrodes of each pad) conducts heat from the pads to other regions of the flexible circuit strip, and the heat in the pads potentially increases the temperature of other locations, such as the polymer portions adjacent to the traces and / or electrodes.

[0016] In some embodiments, the heating of the bonding tool during the bonding process is discontinuous. Here, for example, the power supply to the heating element is a pulsed power supply (e.g., including voltage pulses). Without wishing to be bound by theory, the heating and cooling cycles allow the heating of the elements being connected (e.g., one or more of the pads, the wire connected to the pads, and the solder material) to rise to a temperature suitable for establishing the connection, while theorizing that the heat-sensitive portion of the flexible circuit strip remains below a temperature at which damage can still occur. The high thermal conductivity of the elements being connected (e.g., metal) is theorized to allow the heating and cooling cycles to raise the temperature of the elements being connected while minimally increasing the temperature of the heat-sensitive portion, compared to the low thermal conductivity of other portions of the flexible circuit strip (e.g., polymer).

[0017] In some embodiments, one or more characteristics of the pulsed power supply are controlled using the detected resistance level. For example, here the characteristics include one or more of pulse duration (width), amplitude, and temporal pattern (e.g., frequency). In some embodiments, the control of the pulsed power supply to the heating element is by pulse width modulation (PWM). In some embodiments, the resistance is detected during the bonding process, for example, to provide feedback for controlling the power supply to the heating element during the bonding process.

[0018] In some embodiments, the control is to maintain the resistance below an upper threshold resistance, for example, here the upper threshold resistance is related to the damage temperature of the flexible circuit strip.

[0019] In some embodiments, the control is to ensure the quality of the bonding process (e.g., the quality of heating). Here, if the quality of heating is identified as low, the power supply (e.g., the amplitude of the voltage pulse to the heating element) is increased. In some embodiments, the quality of the bonding process is ensured by maintaining the resistance above a lower threshold resistance, for example, here the threshold is associated with the temperature at which the bonding process is efficient and / or effective. Alternatively or additionally, in some embodiments, the quality of the bonding process is ensured by maintaining the rate of change of resistance during heating (e.g., during the power supply pulse) above a threshold rate.

[0020] In some embodiments, the threshold is determined, for example, for a plurality of flexible circuit strips and / or their electrodes and pads, by detecting the resistance levels at different flexible circuit strip temperatures. Here, in some embodiments, an average value is used to determine the threshold.

[0021] In some embodiments, resistance is additionally detected between the pad connected to the bonding tool. In some embodiments, this "pad resistance" is used, independent of the pad, to determine a part (e.g., the total part) of the "electrode resistance" (the resistance detected between the bonding tool and the electrode) related to the temperature of the flexible circuit strip. In some embodiments, the pad resistance is monitored during the bonding process, where both types of detected resistances are used to control the power supply to the heating element. Alternatively, in some embodiments, the pad resistance is detected during the data collection process, for example, as described above with respect to the determination of the threshold. Here, in some embodiments, the threshold is determined using both types of resistances, where the threshold itself corresponds only to the electrode resistance.

[0022] One aspect of some embodiments of the present disclosure relates to identifying when a sufficient quality electrical and / or mechanical connection is established between the pad and the wire. Here, upon identification, the heating of the bonding tool can be stopped. The potential advantages of an accurate and / or early identification of the establishment of a sufficiently good connection enable a reduction in the heating duration and / or a reduction in the heating temperature.

[0023] In some embodiments, a decrease in resistance is identified from one or both of the pad resistance and the electrode resistance. Here, the decrease is related, for example, to the establishment of the connection and not related to cooling. For example, here, in some embodiments, the decrease is identified during a power supply pulse to the heating element of the bonding tool.

[0024] Alternatively or additionally, in some embodiments, the initial resistance (pad and / or electrode) detected before the initial operation of the bonding tool is compared with the resistance detected after the bonding process and after the flexible circuit strip has cooled to the initial temperature. Here, a decrease in resistance is identified in this comparison. In some embodiments, if this decrease is insufficient, the bonding process can be repeated to increase, for example, the mechanical and / or electrical quality of the connection.

[0025] Before describing in detail at least one embodiment of the present invention, it is to be understood that the invention is not necessarily limited to the details of the structure and arrangement of the components and / or methods described in the following description, and / or illustrated in the drawings and / or examples, in its application. The invention is capable of other embodiments or of being practiced or carried out in various ways.

[0026] Exemplary catheter FIG. 1A is a schematic view of a basket catheter 111 according to some embodiments of the present disclosure.

[0027] The basket catheter 111 includes an elongate deflectable element 112 having a distal end 114, a coupler 116 connected to the distal end 114, and an optional pusher 118. The optional pusher 118 is configured to advance and retract through the deflectable element 112, for example, using a manipulator or handle (not shown). The basket catheter 111 also includes an expandable assembly 122 comprising a plurality of flexible circuit strips 124 (only some are labeled for simplicity), also referred to herein as "flexible splines". Here, in some embodiments, the flexible circuit strip 124 is a polymer circuit strip. Each flexible circuit strip 124 includes a plurality of electrodes 126 (only some are labeled for simplicity) disposed on its upper portion. The formation of the various elements and the way they are connected to each other are described in detail in U.S. Patent Application Publication No. 2021 / 0187241.

[0028] In some embodiments, the form and / or structure of the basket catheter 111 is provided by a basket structure that, in some embodiments, comprises, for example, a plurality of nitinol strips (also referred to herein as "splines") and that is made of nitinol (e.g., formed from nitinol). Here, at least a portion of each of the flexible circuit strips 124 is supported by a corresponding nitinol strip. In some embodiments, the strips of the nitinol basket structure are connected to each other, for example, at the proximal end of the basket catheter 111. The flexible circuit strip 124 can be attached to the nitinol basket structure either before or after establishing an electrical connection to a pad of the flexible circuit strip 124 (e.g., pad 110 of FIG. 1B). In some embodiments, the electrical connection to the pad 110 of the flexible circuit strip 124 is established when the flexible circuit strip is in a flat configuration and / or a non-disconnected configuration (e.g., the configuration illustrated in FIG. 1B), either before or after connecting the flexible circuit strip to the nitinol support structure.

[0029] Exemplary Embodiments of Flexible Circuit Strips FIG. 1B is a top view of the flexible polymer circuit strip 124 prior to assembly for use with the basket catheter of FIG. 1A.

[0030] Referring now to FIG. 1B, which is a schematic view of the flexible polymer circuit strip 124 for use with the basket catheter 111 of FIG. 1A. The flexible polymer circuit strip 124 can be formed from a single polymer component such as polyimide. The circuit strips 124 can be connected to each other by polyimide or assembled as individual components held in proper alignment and secured to the coupler 116 of FIG. 1A. Manufacturing the circuit strip 124 as individual components can increase the yield of the base circuit because, in the event of an electrode failure, only one circuit strip rather than the entire strip assembly is scrapped. Each first end 142 of each flexible polymer circuit strip 124 includes an electrical connection array 160.

[0031] The insertion portion 162 shows that the electrical connection array 160 includes pads 110 on its upper part (only some are labeled for simplicity). The pads 110 are connected to respective electrodes among the electrodes 126 disposed on the front surface of the flexible circuit strip 124 via traces (not shown) optionally located on the rear surface of the flexible circuit strip 124. Away from the region of the first end 142, the flexible circuit strip 124 is separate from each other so as to enable the flexible circuit strip 124 to form an expandable assembly 122 (FIG. 1A) when connected to the basket catheter 111. A wire (not shown) can connect the electrode 126 to a control circuit (not shown) via the pad 110. The wire can be disposed within the lumen (not illustrated) of the elongated deflectable element 112 (FIG. 1A).

[0032] The flexible circuit strip 124 can have any suitable dimensions. For example, the length of the flexible circuit strip 124 can be in the range of 10 mm to 60 mm, such as 30 mm, the width of the flexible circuit strip 124 can be in the range of 0.25 mm to 3 mm, such as 0.72 mm, and the thickness of the flexible circuit strip 124 can be in the range of 0.005 mm to 0.14 mm.

[0033] In some embodiments, the electrodes 126 extend so as to occupy most of the width of the flexible circuit strip 124 in which they are accommodated. Here, in some embodiments, the electrode width 192 is 0.25 to 3 mm, and / or the electrode length 190 is 0.25 to 3 mm.

[0034] In some embodiments, one or more pad dimensions are smaller than the electrode dimensions. Here, the surface area shown by the pad for contact (e.g., to a measurement probe or bonding tool) is smaller than the surface area shown by the electrode. For example, the upper surface area of the pad is 1 to 20% of the surface area of the electrode. For example, the pad width 194 is 0.05 to 0.5 mm, and / or the pad length 196 is 0.1 to 1 mm.

[0035] The surface area 162 of the flexible circuit strip 124 on which the pads 142 are disposed can be small and / or the density of the pads on that area can be high. For example, the area having a width 178 of 0.25 to 3 mm and a length 198 of 0.5 to 6 mm and / or the ratio of the surface area occupied by the pads is 20 to 50%.

[0036] Exemplary electrical connection system FIG. 2 is a schematic diagram of a system 200 for providing an electrical connection to a flexible circuit strip 124 according to some embodiments of the present disclosure.

[0037] In some embodiments, the flexible circuit strip 124 is a part of a catheter having one or more features as illustrated and / or described with respect to the catheter 111 of FIG. 1A. Here, in some embodiments, the flexible circuit strip 124 corresponds to one or more (e.g., each) of the flexible circuit strips 124 of FIGS. 1A and / or 1B.

[0038] In some embodiments, the system 200 includes a joining tool 216 configured to join an electrical connector, such as a wire (not illustrated), to each of the pads 110 (e.g., to one pad at a time). In some embodiments, the joining tool 216 is a thermal joining tool that generates heat and joins by supplying it to the objects to be joined (e.g., a soldering iron, or a welding gun, or an ultrasonic joining tool).

[0039] In some embodiments, the system 200 includes one or more sensors 220, where the sensor 220 is a resistance sensor. In some embodiments, the resistance sensor 220 detects the resistance between the joining tool 216 and an electrode (e.g., the electrode 126a illustrated in FIG. 2). In some embodiments, a probe 242 is used to provide electrical contact to the electrode. Optionally (not illustrated), in some embodiments, the resistance is detected directly between the joining tool 216 and the pad 210a, for example by contacting the pad.

[0040] In FIG. 2, in some embodiments, electrical connections (e.g., for resistance detection) are illustrated by solid lines, and data connections (e.g., transfer of the detected resistance level to controller 218) are illustrated by dashed arrows.

[0041] In some embodiments, the bonding tool 216 is controlled by a controller 218 that receives sensor signals from one or more sensors, e.g., one or more of the resistance sensors 220.

[0042] In some embodiments, the controller 218 generates a control signal for the operation of the bonding tool 216 based on, e.g., the detected resistance level (e.g., from sensor 220). In some embodiments, the controller 218 generates a control signal and transmits it to the power supply 226 of the bonding tool 216, where the control signal controls the power supplied to the heating element 208 by the power supply. Alternatively or additionally, in some embodiments, the controller 218 generates a control signal that is converted (e.g., by a processor) into a control signal for the power supply 226 by the bonding tool.

[0043] In some embodiments, the power supply 226 is configured to supply pulses of power to the heating element 208, where in some embodiments, one or more characteristics of the pulses (e.g., one or more of amplitude, pulse repetition frequency, and pulse duration) are controlled based on the detected resistance. In some embodiments, pulse width modulation (PWM) is used.

[0044] Optionally, in some embodiments, the system 200 includes one or more temperature sensors (not illustrated), e.g., the bonding tool may include a temperature sensor that provides temperature feedback measurements to the controller 218 for control of the temperature of the bonding tool.

[0045] In some embodiments, system 200 includes a rigid support (not illustrated) that provides mechanical support to flexible circuit strip 124, enabling, for example, bonding tool 216 to apply pressure to the pads during the bonding process.

[0046] In some embodiments, flexible circuit strip 124 has at least one (e.g., a plurality of) electrodes 126. Here, electrodes 126 may be disposed on distal portion 206 of flexible circuit strip 124. Electrodes 126 may be disposed on the outer surface of flexible circuit strip 124. For example, one or more of electrodes 126 may protrude from a substantially flat outer surface (e.g., the upper surface) of flexible circuit strip 124, and / or one or more of electrodes 126 may have an electrode upper surface that is coplanar with (or recessed from) the upper surface of flexible circuit strip 124.

[0047] In some embodiments, a plurality of pads 110 are disposed on proximal portion 228 of flexible circuit strip 124. In some embodiments, one or more of electrodes 126, e.g., each electrode, is electrically connected to a corresponding one of the plurality of pads 110. For example, each electrode is connected to the pad by an individual trace 212, and flexible circuit strip 124 includes a plurality of traces 212. In some embodiments, the electrical connection (e.g., a trace or wire) extends through the body 214 of flexible circuit strip 124.

[0048] In some embodiments, flexible circuit strip 124 includes a plurality of layers. Here, for example, wire 212 that connects pad 110 to electrode 126 is sandwiched between at least two layers. Here, in some embodiments, the outer surface 252 (also referred to herein as the "upper surface" 252) of flexible circuit strip 124 houses pads 110 and electrodes 126. In some embodiments, upper surface 252 includes an electrically insulating material (e.g., portions that are not pads or electrodes are formed from a polymer).

[0049] Alternatively or additionally, in some embodiments, the traces are disposed on the back surface 254 of the flexible circuit strip, where, for example, the connectors extend through the body 214 to connect the pads and electrodes to their respective traces. Here, the back surface 254 is, in some embodiments, the surface of the body 214 that generally faces the top surface 252.

[0050] In some embodiments, the bonding tool 216 is automatically movable relative to the flexible circuit strip 124 (e.g., by one or more actuators) to move the bonding tool between the positions of the plurality of pads. Here, in some embodiments, one or both of the bonding tool 216 and the support on which the flexible circuit strip is disposed are movable relative to each other. In some embodiments, the positioning of the bonding tool 216 relative to the flexible circuit strip 123 is controlled by the controller 218.

[0051] In some embodiments, the bonding tool tip 238 includes a cover on the outer surface, e.g., a cover including a material that is highly conductive and / or thermally conductive and / or heat resistant. For example, the bonding tool includes a cover configured to cover (e.g., surround) at least a portion of the bonding tool 216 between the regions of electrical contact between the resistance sensor 220 and the bonding tool 216. In some embodiments, the resistance characteristics and / or capacitance characteristics of the bonding tool (e.g., in relation to high conductivity and / or thermal conductivity) have low temperature dependence.

[0052] In some embodiments, at least a portion of the bonding tool (e.g., the tip 238 and / or a portion of the tip) that contacts the pad while establishing a connection to the pad is non-adhesive to the material of the pad 110, e.g., at the temperature used while establishing a connection to the pad. If the bonding tool is a soldering iron, the material of the bonding tool that contacts the solder can be non-adhesive to the solder and, for example, alternatively or additionally, non-adhesive to the pad surface.

[0053] In some embodiments, the region of the bonding tool tip and / or the cover and / or the bonding tool in the electrical path between the bonding tool and the sensor 208 contains gold (e.g., is formed of gold).

[0054] In some embodiments, user instructions (e.g., to initiate a bonding process) are received through one or more user interfaces (UI) 236, and / or information is transferred to the user through one or more user interfaces (UI) 236. Here, in some embodiments, data is transferred between the UI 236 and the controller 218. For example, in some embodiments, user instructions are transferred by the UI 236 to the controller 218, and the controller 218, in some embodiments, controls the operation of the system 200 based on the user instructions. One or more UIs may be local to the bonding tool 216 and / or other system components, and / or one or more UIs may be located remotely.

[0055] Optionally, in some embodiments, the external processing and / or memory circuit 234 communicates with the UI 236 and / or the controller 218. For example, the circuit 234 enables remote control of the system 200, e.g., via a remote UI.

[0056] Exemplary Electrical Connection Method FIG. 3A is a method for establishing a connection to a workpiece according to some embodiments of the present disclosure.

[0057] At 304, in some embodiments, the resistance between the bonding tool and the electrode is detected.

[0058] At 306, in some embodiments, the operation and / or temperature of the bonding tool is controlled based on the detected resistance level. In an exemplary embodiment, the operation of the bonding tool is controlled by controlling the power supplied to the heating element of the bonding tool.

[0059] In some embodiments, the heating of the bonding tool during the bonding process is discontinuous. Here, for example, the power supply to the heating element is a pulsed power supply (e.g., including voltage pulses).

[0060] In some embodiments, one or more characteristics of the pulsed power supply are controlled using the detected resistance. For example, here, the characteristics include one or more of pulse duration (width), amplitude, and temporal pattern (e.g., frequency). In some embodiments, the control of the pulsed power supply to the heating element is by pulse width modulation (PWM). In some embodiments, the resistance is detected during the bonding process and provides feedback, for example, for controlling the power supply to the heating element during the bonding process.

[0061] In some embodiments, the control is to maintain the resistance below an upper threshold resistance. For example, here, the threshold is associated with a flexible circuit strip reaching a damage temperature.

[0062] Optionally, in some embodiments, the control is to ensure the quality of the bonding process (e.g., the quality of heating). Here, if the quality of heating is identified as low, the power supply (e.g., voltage, e.g., the amplitude of the voltage pulse to the heating element) is increased. In some embodiments, the quality of the bonding process is ensured by maintaining the resistance above a lower threshold resistance. For example, here, the threshold is associated with a temperature at which the bonding process is efficient and / or effective. Alternatively or additionally, in some embodiments, the quality of the bonding process is ensured by maintaining the rate of change of the resistance during heating (e.g., during a power supply pulse) above a threshold rate.

[0063] In some embodiments, the threshold value is received, for example, from a memory (such as that of circuit 234). In some embodiments, the threshold value is provided by a user, for example, through a user interface. In some embodiments, the threshold value is determined by detecting resistance while heating the flexible circuit strip to different temperatures, for example, by detecting resistance levels at different flexible circuit strip temperatures for a plurality of flexible circuit strips and / or their electrodes and pads. In some embodiments, an average is used to determine the threshold value.

[0064] Figure 3B is a method for establishing a connection to a workpiece according to some embodiments of the present disclosure.

[0065] At 301, in some embodiments, a resistance measurement circuit is set. For example, here, a measurement probe is brought into contact with an electrode corresponding to a pad (such as probe 242, electrode 126a, and pad 210a in FIG. 2). In some embodiments, the resistance measurement circuit has a fixed position. For example, the connection to the electrode for determining resistance is provided by a jig, and here, for example, positioning the flexible circuit strip for the electrical connection process sets the resistance measurement circuit.

[0066] At 303, in some embodiments, the tip of the bonding tool (such as tip 238 of bonding tool 216 in FIG. 2) is brought close to (such as into contact with) a pad and / or a wire connected to the pad and / or solder (such as when the bonding tool is a soldering iron). In some embodiments, the proximity is such that sufficient heat is conducted from the bonding tool to the pad and / or wire and / or solder to be sufficient to melt the connection process, such as the solder and / or pad and / or wire material. In some embodiments, the positioning of the bonding tool is an automated process. For example, here, one or more actuators controlled by a controller (such as controller 218 in FIG. 2) are configured to move the bonding tool relative to the flexible circuit strip.

[0067] At 305, in some embodiments, the electrode resistance is monitored according to, for example, one or more features of step 300 in FIG. 3A.

[0068] At 307, optionally, in some embodiments, the resistance is additionally monitored between the bonding tool and the pad to which it is connected. In some embodiments, this “pad resistance” is used to determine a portion of the “electrode resistance” (the resistance detected between the bonding tool and the electrode at step 305), which is associated with the temperature of the traces and electrodes, independent of, for example, the pads indicating the temperature of the flexible circuit strip.

[0069] In some embodiments, both resistances are monitored during the bonding process and used to control the power supply to the heating element.

[0070] Alternatively, in some embodiments, the pad resistance is detected during the data collection process, as described, for example, in step 302 of determining the threshold. In some embodiments, the threshold is determined from the data collection of both detected types of resistance, but the detected electrode resistance level (e.g., the electrode resistance level only) is used during the bonding process.

[0071] At 309, optionally, in some embodiments, the detected electrode resistance and / or pad resistance are used to identify the contact between the bonding tool and the pad and / or to verify that the quality of the contact is sufficient. Here, in some embodiments, the contact is identified as a detected decrease in resistance (e.g., the slope of the resistance decrease is above a threshold) and / or as a detected resistance that drops below a threshold.

[0072] If contact is not verified and / or the quality of the contact is not verified (e.g., the detected resistance is higher than a threshold value), the tip can be repositioned, for example, back to step 303. Here, for example, the tip can be moved towards the pad to increase the pressure, for example, between the pad and the tip to improve the electrical and / or thermal contact therebetween.

[0073] In 311, in some embodiments, the heating of the bonding tool tip is controlled using the detected resistance. Here, for example, electrode resistance can be used according to one or more features of step 302 of FIG. 3A, and optionally, here, pad resistance can additionally be used.

[0074] In 313, in some embodiments, the quality of the connection between the wire and the pad is evaluated using the detected resistance. For example, in some embodiments, a decrease in resistance is identified in one or both of the pad resistance and the electrode resistance. This decrease can be related to, for example, the establishment of an electrical connection rather than cooling. For example, here, in some embodiments, the decrease is identified during a power supply pulse to the heating element of the bonding tool. In some embodiments, the decrease is identified when the solder and / or wire form part of the circuit where the resistance is detected. Without wishing to be bound by theory, it is theorized that the melting of the solder and / or wire onto the pad reduces the resistance from the bonding tool through the pad, for example, in relation to improving the electrical connection therebetween.

[0075] Optionally, in some embodiments, upon identification, the heating of the bonding tool can be stopped. The potential advantages of accurate and / or early identification of a well-established connection sufficiently enable a reduction in the heating duration and / or a reduction in the heating temperature.

[0076] Alternatively or additionally, in some embodiments, the initial resistance (pad and / or electrode) detected at the initial temperature and prior to activation of the bonding tool is compared to the resistance detected after the bonding process and after the flexible circuit strip has been cooled to the initial temperature. Here, a decrease in resistance is identified in this comparison. In some embodiments, if this decrease is insufficient, the bonding process may be repeated to, for example, increase the mechanical and / or electrical quality of the connection.

[0077] FIG. 4 is a simplified plot of resistance over time according to some embodiments of the present disclosure.

[0078] In some embodiments, FIG. 4 illustrates the detected resistance between a bonding tool (e.g., bonding tool 216) and a pad (e.g., pad 210a) to which the bonding tool has established a connection. Here, the resistance may be detected at the electrode as "electrode resistance".

[0079] Here, initially at 400, prior to the bonding tool contacting the pad, the detected resistance is high, for example, related to the electrical insulating material (e.g., air) between the bonding tool and the pad.

[0080] As the bonding tool approaches the pad, the detected resistance may decrease (401) until contact is made at 402 between the pad and the bonding tool. Here, one or both of the slope of the decrease 401 and the detected lower resistance (e.g., less than a threshold resistance and / or less than a percentage of the detected initial resistance) are used to identify and / or verify the contact between the bonding tool and the pad.

[0081] Heating of the bonding tool during period 404 may increase the detected resistance, which increase is related, for example, to an increase in the temperature of the flexible circuit strip. In some embodiments, for example, as described in the method of FIGS. 3A and / or 3B, the heating of the bonding tool may be controlled during period 404, for example, to maintain the resistance R below a threshold.

[0082] In some embodiments, when a connection is established, the resistance R may decrease. Here, for example, the desired decrease in resistance as illustrated in 406 is associated in some embodiments with the establishment of a good solder connection. In some embodiments, when the desired decrease in resistance is identified, the heating of the bonding tool is stopped. Here, in some embodiments, the peak resistance is identified and that value is used to determine a desired decrease that may be a given resistance or percentage of the peak resistance. In some embodiments, the desired decrease is identified as the resistance that reaches (e.g., drops to) a given value after the identified peak.

[0083] In some embodiments, the final resistance 408 detected after heating (and optionally cooling) is used to evaluate the quality of the connection. Here, in some embodiments, the quality of the connection is verified when the detected resistance is lower than a threshold value and / or a lower percentage and / or value than the resistance detected prior to executing 402 of the thermal bonding process.

[0084] FIGS. 5A-5E are schematic diagrams illustrating the establishment of an electrical connection to pad 210a using bonding tool 216, according to some embodiments of the present disclosure.

[0085] Here, in some embodiments, FIGS. 5A-5E illustrate a portion of flexible circuit strip 124, e.g., the same portion during the establishment of an electrical connection to pad 210a. In some embodiments, the higher temperature and / or heating is illustrated in FIGS. 5A-5E by the shading.

[0086] Referring now to FIG. 5A, in some embodiments, the bonding tool 216 (e.g., the tip of the bonding tool) is brought into contact with the pad 210a and / or the wire 550 that is in contact with the pad 210a. The bonding tool is then heated, for example, as illustrated by the shading of the bonding tool 216 in FIG. 5A. In FIG. 5B, heat from the bonding tool 216 conducts to the wire 550, raising the temperature of the wire 550. In some embodiments, heating of the wire 550 is sufficient to connect the wire to the pad via welding.

[0087] In some embodiments, heating of the bonding tool 216 continues as illustrated in FIG. 5C, for example, where heat conducts to the pad 210a, raising the temperature of the pad. In some embodiments, this heating of both the wire and the pad is sufficient to connect the wire to the pad via welding.

[0088] In some embodiments, the bonding tool 216 is a soldering iron. Here, one or both of the pad and the wire may include solder, and / or here, the solder may be positioned in contact with one or more of the pad, the bonding tool, and the wire. The bonding tool may contact one or more of the pad, the wire, and the solder material. The bonding tool can then be heated to melt the solder and connect the pad and the wire.

[0089] Referring now to FIG. 5D, heat conducts from the pad 210a to the upper portion 552 of the flexible circuit strip 124, raising its temperature. As heating continues, the temperature rise of the upper layer of the flexible circuit strip 124 adjacent to, for example, the portion 552, can extend to the pads adjacent to the pad 210a.

[0090] In some embodiments, this situation is avoided and / or the temperature of the flexible circuit strip is maintained below a temperature at which damage would occur to the flexible circuit strip 124 due to sporadic (e.g., switched) heating of the bonding tool. The switching potentially prevents overheating of the flexible circuit strip material where the material is thermally insulating (e.g., as contrasted with the pad material). Here, for example, before reaching the situation illustrated in FIG. 5D, the heating of the bonding tool is stopped, e.g., the power to the heating element of the bonding tool is disconnected as illustrated in FIG. 5E. Here, in some embodiments, the bonding tool can be repeatedly heated, e.g., cycled to heat the wire 550 and / or the pad 210a to a temperature associated with a good quality connection without damaging the flexible circuit strip.

[0091] General As used herein, the term "about" refers to ±20%.

[0092] The terms "comprises", "comprising", "includes", "including", "having", and their composites mean "including but not limited to".

[0093] The term "consisting of" means "including and limited to".

[0094] As used herein, unless the context specifically dictates otherwise, singular forms, e.g., "a", "an", and "the", include plural referents.

[0095] Within this application, various quantifications and / or expressions may include the use of ranges. The range format should not be construed as an inflexible limitation on the scope of the present disclosure. Thus, descriptions that include ranges should be considered to specifically disclose all possible sub-ranges, as well as the individual numerical values within those ranges. For example, a description of a range such as 1 to 6 should be considered to have specifically disclosed sub-ranges such as 1 to 3, 1 to 4, 1 to 5, 2 to 4, 2 to 6, 3 to 6, as well as the individual numbers within the recited range and / or sub-ranges, for example, 1, 2, 3, 4, 5, and 6. Whenever a numerical range is indicated herein, it is meant to include any recited number (fractional or integral) within the indicated range.

[0096] It is understood that certain features that are described in the context of separate embodiments (for example, for clarity) may also be provided in combination in a single embodiment. Here, various features of the present disclosure that are described in the context of a single embodiment (for example, for brevity) may also be provided separately, or in any suitable partial combination, or may be suitable for use with any other described embodiment. Features described in the context of various embodiments should not be considered essential features of those embodiments, except where the embodiment would not be operable without those elements.

[0097] Although the present disclosure has been described with its specific embodiments, it is obvious that many alternatives, modifications, and variations will be apparent to those skilled in the art. Therefore, this application is intended to cover all such alternatives, modifications, and variations that fall within the spirit and broad scope of the appended claims.

[0098] All references cited in this specification (e.g., publications, patents, and patent applications) are hereby incorporated by reference in their entirety as if each individual publication, patent, or patent application was individually indicated to be incorporated herein by reference. The citation or identification of any reference in this application should not be construed as an admission that such reference is available as prior art to the present disclosure. In addition, any priority documents and / or documents related to this application (e.g., co-pending applications) are hereby incorporated by reference in their entirety.

[0099] When section headings are used in this specification, they should not necessarily be construed as limiting.

[0100] General Description The following is a non-exclusive list of some exemplary embodiments of the present disclosure. The present disclosure also includes embodiments that include fewer features than all of the features in a given example, and embodiments that use features from multiple examples, even if not listed below.

[0101] Example 1. A method of electrically connecting a wire (550) to a connection pad (210a) of a flexible circuit strip (124) using a thermal bonding tool (216), the flexible circuit strip including a polymer body (214), a plurality of electrodes (126), a plurality of connection pads (110), and a plurality of conductive traces (212), the traces connecting each of the plurality of electrodes (126) to a connection pad among the plurality of connection pads (110), the method comprising positioning the bonding tool (216) in proximity to the connection pad (210a) of the plurality of connection pads (110) and the wire (550) connected to the connection pad (210a); actuating the bonding tool (216) to heat the tip (238) of the bonding tool (216) to electrically connect the wire (550) to the connection pad (210a); During the operation, monitoring the resistance between the bonding tool (216) and the electrode (126a) electrically connected to the connection pad (210a), wherein the resistance indicates the temperature of the flexible circuit strip (124), and controlling the operation so as to maintain the resistance below an upper threshold value associated with the flexible circuit strip (124) that reaches the damage temperature, the method comprising.

[0102] Example 2. The method according to Example 1, wherein the actuating comprises supplying a plurality of electrical pulses to one or more heating elements of the bonding tool.

[0103] Example 3. The method according to Example 2, wherein the plurality of electrical pulses are voltage supply pulses to the one or more heating elements.

[0104] Example 4. The method according to Example 2 or 3, wherein the controlling comprises controlling one or more characteristics of the plurality of electrical pulses.

[0105] Example 5. The one or more characteristics of the plurality of electrical pulses are the method according to Example 4, comprising one or more of pulse duration, pulse repetition frequency, and pulse amplitude.

[0106] Example 6. The method according to Example 4, wherein the controlling one or more characteristics of the plurality of electrical pulses comprises pulse width modulation (PWM) of an actuation signal to the bonding tool (216).

[0107] Example 7. The method according to any one of Examples 1 to 4, wherein the controlling comprises maintaining the resistance above a lower threshold value.

[0108] Example 8. comprising determining a rate of change of the resistance, the method according to any one of Examples 2 to 7, wherein the controlling is by using the rate of change.

[0109] Example 9. The determining includes determining that the change rate of the resistance is below a threshold value. The controlling includes increasing the amplitude of the power pulse, the method according to Example 8.

[0110] Example 10. The controlling includes identifying a portion of the resistance associated with the connection between the wire (550) and the connection pad (210a), and detecting a decrease in the portion of the resistance, the method according to any one of Examples 2 to 9.

[0111] Example 11. The method according to Example 10, including stopping the operation of the bonding tool (216) when the decrease in the portion of the resistance is detected.

[0112] Example 12. The method according to Example 11, wherein the detecting the decrease in the resistance is performed during the supply of the pulse among the plurality of electric pulses.

[0113] Example 13. storing an initial measured value of the resistance before the operation when the flexible strip is at an initial temperature, and stopping the operation of the bonding tool (216), including the detecting the decrease in the resistance includes comparing the initial measured value of the resistance with the resistance after the flexible strip is cooled to the initial temperature, the method according to Example 10.

[0114] Example 14. The method according to any one of Examples 10 to 13, including evaluating the quality of the connection between the wire (550) and the connection pad (210a) based on the decrease in the resistance.

[0115] Example 15. The method according to Example 14, wherein the quality is one or more of the thermal, electrical, and mechanical connection qualities between the wire and the connection pad.

[0116] Example 16. The method according to any one of Examples 14 to 15, including repeating the actuation based on the evaluation.

[0117] Example 17. The method according to any one of Examples 14 to 16, including adjusting one or more characteristics of the supply based on the evaluation.

[0118] Example 18. A system for electrically connecting a wire (550) to a connection pad (210a) of a flexible circuit strip (124) including a polymer body (214), a plurality of electrodes (126), a plurality of connection pads (110), and a plurality of conductive traces (212), wherein the traces connect each of the plurality of electrodes (126) to a connection pad among the plurality of connection pads (110), A thermal bonding tool (216) having one or more heating elements, A sensor (220) configured to measure a resistance between the bonding tool (216) and an electrode (126a) electrically connected to a connection pad (210a) among the plurality of connection pads (110), the resistance indicating the temperature of the flexible circuit strip (124), the sensor (220), A controller (218), Receiving a measured value of the resistance from the sensor (220), A controller (218) configured to control the operation of the one or more heating elements to heat the tip (238) of the bonding tool (216) to connect the connection pad (210a) and the wire (550) in proximity to the tip (238), while maintaining the resistance below an upper threshold associated with the flexible circuit strip (124) reaching a damage temperature, the system comprising.

[0119] Controller (218) for controlling the electrical connection of wire (550) to connection pad (210a) of flexible circuit strip (124) using a thermocompression bonding tool (216), the flexible circuit strip including a polymer body (214), a plurality of electrodes (126), a plurality of connection pads (110), and a plurality of conductive traces (212), the traces connecting each of the plurality of electrodes (126) to a connection pad among the plurality of connection pads (110), the controller (218) activating the bonding tool to heat the tip (238) of the bonding tool (216) to electrically connect the wire (550) to the connection pad (110a); during the activation, measuring the resistance between the bonding tool (216) and an electrode (126a) electrically connected to the connection pad (210a), the resistance indicating the temperature of the flexible circuit strip (124); controlling the operation of the bonding so as to maintain the resistance below an upper threshold associated with the flexible circuit strip (124) reaching a damage temperature. A controller comprising a circuit configured to perform the above.

[0120] 〔Embodiment〕 (1) A method of electrically connecting a wire to a connection pad of a flexible circuit strip using a thermocompression bonding tool, the flexible circuit strip including a polymer body, a plurality of electrodes, a plurality of connection pads, and a plurality of conductive traces, the traces connecting each of the plurality of electrodes to a connection pad among the plurality of connection pads, the method comprising: positioning the bonding tool in proximity to a connection pad among the plurality of connection pads and the wire connected to the connection pad; activating the bonding tool to heat the tip of the bonding tool to electrically connect the wire to the connection pad; during the activation, monitoring the resistance between the bonding tool and an electrode electrically connected to the connection pad, the resistance indicating the temperature of the flexible circuit strip. Controlling the operation to maintain the resistance below a defined threshold associated with the flexible circuit strip before reaching a defined damage temperature. A method comprising this is provided. (2) The method according to embodiment 1, wherein the actuating comprises supplying a plurality of electrical pulses to one or more heating elements of the joining tool. (3) The method according to embodiment 2, wherein the plurality of electrical pulses are voltage supply pulses to the one or more heating elements. (4) The method according to embodiment 2, wherein the controlling comprises controlling one or more characteristics of the plurality of electrical pulses. (5) The one or more characteristics of the plurality of electrical pulses are The method according to embodiment 4, comprising one or more of pulse duration, pulse repetition frequency, and pulse amplitude.

[0121] (6) The method according to embodiment 4, wherein the controlling one or more characteristics of one of the plurality of electrical pulses comprises pulse width modulation (PWM) of an actuation signal to the joining tool. (7) The method according to embodiment 1, wherein the controlling comprises maintaining the resistance above a lower threshold. (8) Comprising determining a rate of change of the resistance, The method according to embodiment 2, wherein the controlling is using the rate of change. (9) The determining comprises determining that the rate of change of the resistance is below a threshold, The method according to embodiment 8, wherein the controlling comprises increasing the amplitude of the power pulse. (10) The controlling comprises Identifying a portion of the resistance associated with a connection between the wire and the connection pad, Detecting a decrease in the portion of the resistance. The method according to embodiment 2 comprises these.

[0122] (11) The method according to embodiment 10, comprising stopping the operation of the bonding tool when a decrease in the portion of the resistance is detected. (12) The method according to embodiment 11, wherein detecting the decrease in the resistance is performed during the supply of the pulses among the plurality of electrical pulses. (13) When the flexible strip is at an initial temperature, storing an initial measured value of the resistance before operating, and stopping the operation of the bonding tool, and detecting the decrease in the resistance includes comparing the initial measured value of the resistance with the resistance after the flexible strip is cooled to the initial temperature. The method according to embodiment 10. (14) The method according to embodiment 10, comprising evaluating the quality of the connection between the wire and the connection pad based on the decrease in the resistance. (15) The method according to embodiment 14, wherein the quality is one or more of the thermal, electrical, and mechanical connections between the wire and the connection pad. (16) The method according to embodiment 14, comprising repeating the operating based on the evaluating.

[0123] (17) The method according to embodiment 14, comprising adjusting one or more characteristics of the supplying based on the evaluating. (18) A system for electrically connecting a wire to a connection pad of a flexible circuit strip, comprising a polymer body, a plurality of electrodes, a plurality of connection pads, and a plurality of conductive traces, wherein the traces connect each of the plurality of electrodes to a connection pad among the plurality of connection pads, a thermocompression bonding tool having one or more heating elements, a sensor configured to measure a resistance between the bonding tool and an electrode electrically connected to the connection pad, the resistance indicating the temperature of the flexible circuit strip, and a controller, ​Receive the measured value of the resistance from the sensor, A controller configured to control the operation of the one or more heating elements to heat the tip of the bonding tool to connect the wire to a connection pad among the plurality of connection pads in proximity to the tip, while maintaining the resistance below a defined threshold associated with the flexible circuit strip reaching a defined damage temperature. A system comprising the controller. (19) A controller for controlling the electrical connection of a wire to a connection pad of a flexible circuit strip using a thermocompression bonding tool, the flexible circuit strip including a polymer body, a plurality of electrodes, a plurality of connection pads, and a plurality of conductive traces, the traces connecting each of the plurality of electrodes to a connection pad among the plurality of connection pads, the controller Actuating the bonding tool to heat the tip of the bonding tool and electrically connecting the wire to the connection pad; During the actuation, measuring the resistance between the bonding tool and an electrode electrically connected to the connection pad, the resistance indicating the temperature of the flexible circuit strip; A controller comprising a circuit configured to control the operation of the bonding so as to maintain the resistance below a defined threshold associated with the flexible circuit strip reaching a defined damage temperature.

Claims

1. 1. A system for electrically connecting wires to connection pads of a flexible circuit strip, comprising: a polymer body, a plurality of electrodes, a plurality of connection pads, and a plurality of conductive traces, the traces connecting each of the plurality of electrodes to a connection pad of the plurality of connection pads; a thermal bonding tool comprising one or more heating elements; a sensor configured to measure a resistance between the bonding tool and an electrode electrically connected to a connection pad of the plurality of connection pads, the resistance being indicative of a temperature of the flexible circuit strip; and A controller, receiving a measurement of the resistance from the sensor; a controller configured to control operation of the one or more heating elements to heat the tip of the bonding tool to connect the connection pad and a wire proximate to the tip while maintaining the resistance below an upper threshold associated with the flexible circuit strip reaching a damage temperature.

2. The system of claim 1 , wherein the controller is configured to control operation by controlling the delivery of a plurality of electrical pulses to the one or more heating elements.

3. The system of claim 2 , wherein the plurality of electrical pulses are voltage supply pulses to the one or more heating elements.

4. The system of claim 2 or 3, wherein the controller is configured to control one or more characteristics of the plurality of electrical pulses.

5. 5. The system of claim 4, wherein the one or more characteristics of the plurality of electrical pulses comprises one or more of a pulse duration, a pulse repetition frequency, and a pulse amplitude.

6. The system of claim 4 , wherein the controller is configured to control the one or more characteristics of the plurality of electrical pulses by pulse width modulation (PWM) of an actuation signal to the bonding tool.

7. The system of claim 1 , wherein the controller is configured to maintain the resistance above a lower threshold.

8. The controller: determining a rate of change of the resistance; The system of claim 2 , configured to use the rate of change of the resistance to control the operation of the one or more heating elements.

9. The controller: determining whether the rate of change of the resistance is below a threshold; The system of claim 8 , configured to control the actuation by increasing an amplitude of the plurality of power pulses.

10. The controller identifying a portion of the resistance associated with a connection between the wire and the connection pad; detecting a decrease in said portion of said resistance; The system of claim 2 , configured to deactivate the bonding tool when the decrease in the portion of the resistance is detected.

11. The system of claim 10 , wherein the controller is configured to detect the decrease in the resistance that occurs during the delivery of a pulse of the plurality of electrical pulses.

12. The controller: storing an initial measurement of the resistance when the flexible strip is at an initial temperature and prior to activating the one or more heating elements; configured to deactivate the bonding tool; 11. The system of claim 10, wherein the controller is configured to detect the decrease in resistance by comparing the initial measurement of the resistance to the resistance after the flexible strip has cooled to the initial temperature.

13. The system of claim 10 , wherein the controller is configured to assess a quality of a connection between the wire and the connection pad based on the decrease in resistance.

14. The controller: cycling the activation of the one or more heating elements based on the quality of the connection; and and adjusting one or more characteristics of the delivery of the plurality of electrical pulses based on a quality of the connection.

15. 1. A method of electrically connecting wires to connection pads of a flexible circuit strip using a thermal bonding tool, the flexible circuit strip including a polymer body, a plurality of electrodes, a plurality of connection pads, and a plurality of conductive traces, the traces connecting each of the plurality of electrodes to a connection pad of the plurality of connection pads, the method comprising: positioning the bonding tool proximate a connection pad of the plurality of connection pads and the wire connected to the connection pad; activating the bonding tool to heat a tip of the bonding tool to electrically connect the wire to the connection pad; monitoring a resistance between the bonding tool and an electrode electrically connected to the connection pad during said actuation, the resistance being indicative of a temperature of the flexible circuit strip; and controlling the actuation to maintain the resistance below an upper threshold associated with the flexible circuit strip reaching a damage temperature.

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