Automatic control of electrical connection joining process

Abstract

A method of electrically connecting a wire to a connection pad of a flexible circuit strip using a thermal bonding tool wherein the flexible circuit strip includes a polymeric body, a plurality of electrodes, a plurality of connection pads, and a plurality of conductive traces connecting each of the plurality of electrodes to a connection pad of the plurality of connection pads, the method includes: positioning a bonding tool near a connection pad of the plurality of connection pads and a wire to be 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; during activation, monitoring a resistance between the bonding tool and an electrode electrically connected to the connection pad, the resistance indicating a temperature of the flexible circuit strip; and controlling the activation to maintain the resistance below an upper threshold associated with the flexible circuit strip reaching a damage temperature.

Description

[0001] Related Applications

[0002] This application claims priority to U.S. Provisional 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. Technical Field

[0003] In some embodiments, the present disclosure relates to catheter manufacturing, and more particularly but not exclusively to establishing electrical connections with flexible circuit strips of a catheter. Background Art

[0004] A wide range of medical procedures involve placing probes, such as catheters, inside a patient's body. Electrode catheters have been commonly used in medical practice for many years. They are used to stimulate and map electrical activity in the heart and to ablate sites of abnormal electrical activity.

[0005] The wall cavities of a patient's organ, such as a heart chamber, can be mapped and / or ablated using a catheter having a plurality of electrodes assembled at an expandable distal end assembly of the catheter. The expandable distal end assembly is coupled at 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 for sensing and / or delivering a treatment signal. Brief Description of the Drawings

[0006] To better understand the subject matter disclosed herein and to illustrate how the subject matter may be practiced in practice, embodiments are now described by way of non-limiting example only with reference to the accompanying drawings, in which:

[0007] Figure 1A is a schematic view of a basket catheter according to some embodiments of the present disclosure;

[0008] Figure 1B is a simplified schematic view of a flexible polymer circuit strip according to some embodiments of the present disclosure;

[0009] Figure 2 is a simplified schematic view of a system for establishing an electrical connection with a flexible circuit strip according to some embodiments of the present disclosure;

[0010] Figure 3A is a method of establishing a connection with a workpiece according to some embodiments of the present disclosure.

[0011] Figure 3B is a method of establishing a connection with a workpiece according to some embodiments of the present disclosure.

[0012] Figure 4is a simplified schematic graph showing the change of resistance over time according to some embodiments of the present disclosure; and

[0013] Figures 5A to 5E is a simplified schematic diagram showing the establishment of an electrical connection with a pad using a bonding tool according to some embodiments of the present disclosure.

[0015] In some embodiments, although not restrictive, the same elements are denoted by the same reference numerals. Detailed Description

[0016] The present disclosure, in some of its embodiments, relates to catheter manufacturing and, more specifically but not exclusively, to establishing an electrical connection with a flexible circuit strip of a catheter.

[0017] Overview

[0018] Some catheters (such as basket catheters) may have a number of (e.g., 30 - 100) electrodes mounted on multiple splines of a basket, which is coupled to a connector at the proximal end of the shaft of the catheter through the shaft. In some embodiments, the electrodes may be accommodated by a plurality of flexible printed circuit boards (PCBs), each flexible printed circuit board being mounted on a spline of the basket. Both the flexible PCB (also referred to herein as "flexible circuit strip") on the spline and the PCB of the connector have pads, and multiple wires (e.g., wires for each electrode) extending through the shaft provide electrical coupling. The distal end of each wire is coupled to a predefined pad on the spline, and the proximal end of each wire is coupled to a corresponding pad in the connector so as to exchange electrical signals between the electrodes and a console (e.g., the PIU (patient interface unit) of the catheter) via the shaft. Due to limited space on the spline, the pads need to cover a small area. For example, for each pad on a printed circuit board, the pad size (e.g., surface area) may be on the order of dozens of square micrometers (also referred to herein as square microns), resulting in the coupling process between the wire and the corresponding pad being very time-consuming and / or expensive. The pads may also be placed close to each other. For example, the spacing between pads is less than the length and / or width of the pad, and / or the spacing between adjacent pads is less than 0.1 mm - 0.5 mm. The pads may densely occupy the area on the flexible circuit strip. For example, the proportion of the surface area occupied by the pads is 20% - 50%.

[0019] In manufacturing, thermally bonding (e.g., soldering or brazing) a number of wires to a number of pads of a flexible circuit strip (e.g., sequentially) (e.g., involving repeated heating of the wires and pads) can raise the temperature of the flexible circuit strip, e.g., to a level at which the strip material (e.g., the polymer body of the flexible circuit strip) is damaged. For example, the heat applied to connect a wire to one pad, which is associated with the repeated heating for the connection to multiple pads, may cause unwanted heating of another adjacent pad already connected to the wire, e.g., further affecting the polymer body around the previously connected and heated pad and / or potentially degrading the quality of the connection already established.

[0020] Broad aspects of some embodiments of the present disclosure relate to monitoring the resistance between a bonding tool that connects a wire to a pad and an electrode corresponding to the pad. The resistance and / or the change in resistance over time potentially provides an indication of the temperature of the flexible polymer strip. For example, an increase in resistance generally indicates a rise in temperature. For example, since the detected resistance includes the resistance of the pad, the resistance of the electrode, and the resistance of the trace connecting the pad and the electrode, each resistance may be affected by temperature.

[0021] One aspect of some embodiments of the present disclosure relates to establishing an electrical connection with a pad of a flexible circuit strip using a bonding tool, wherein the heating of the bonding tool used to form the connection is controlled using the resistance detected between the bonding tool and the electrode connected to the pad.

[0022] In some embodiments, the flexible circuit strip includes a thermosensitive material (e.g., including a polymer). Thermosensitivity can be manifested as deformation and / or chemical change of the material by exposure to a temperature above a threshold and / or an elevated temperature for a duration exceeding a threshold.

[0023] The detected resistance potentially indicates the temperature of the polymer body of the flexible polymer strip. For example, compared with electrical components, the polymer body may be prone to temperature rise during the connection process, and this rise is related to the thermal insulation properties of the polymer material.

[0024] In some embodiments, the flexible circuit strip includes a plurality of pads, and, for example, a plurality of connections to each of the plurality of pads are established sequentially and / or using a single bonding tool.

[0025] In some embodiments, the pads are closely packed and / or directly disposed on the thermosensitive material (e.g., the polymer body). In some embodiments, the 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 at the pads potentially raises the temperature of the polymer portions elsewhere (e.g., adjacent to the traces and / or electrodes).

[0026] In some embodiments, heating of the bonding tool during the bonding process is discontinuous. For example, the power source for the heating element is a pulsed power source (e.g., including voltage pulses). Without wishing to be bound by theory, theoretically, the cycle of heating and cooling enables heating of the elements to be joined (e.g., one or more of the pads, the wire to be joined to the pad, and the solder material) to a temperature suitable for establishing a connection, while the thermally sensitive portions of the flexible circuit strip remain below a temperature at which damage may occur. Theoretically, the high thermal conductivity of the elements being joined (e.g., metals) compared to the low thermal conductivity of other portions of the flexible circuit strip (e.g., polymers) enables a heating and cooling cycle to raise the temperature of the elements to be joined while minimally raising the temperature of the thermally sensitive portions.

[0027] In some embodiments, a detected resistance level is used to control one or more characteristics of the pulsed power source. For example, the characteristics include one or more of pulse duration (width), amplitude, and time pattern (e.g., frequency). In some embodiments, the pulsed power source for the heating element is controlled by pulse width modulation (PWM). In some embodiments, resistance is detected during the bonding process, e.g., to provide feedback for controlling the power source for the heating element during the bonding process.

[0028] In some embodiments, the control is to keep the resistance below an upper threshold resistance, e.g., the upper threshold resistance is associated with the damage temperature of the flexible circuit strip.

[0029] In some embodiments, the control is to ensure the quality of the bonding process (e.g., the quality of heating). Wherein, if the quality of heating is identified as low, the power supply is increased (e.g., the amplitude of the voltage pulse to the heating element). In some embodiments, the quality of the bonding process is ensured by keeping the resistance above a lower threshold resistance, e.g., the threshold is associated with the temperature when the bonding process is efficient and / or effective. Alternatively or in addition, in some embodiments, the quality of the bonding process is ensured by keeping the rate of change of resistance above a threshold rate during heating (e.g., during the power source pulse).

[0030] In some embodiments, the threshold is determined by detecting the resistance levels of, for example, multiple flexible circuit strips and / or their electrodes and pads at different flexible circuit strip temperatures. Wherein, in some embodiments, an average value is used to determine the threshold.

[0031] In some embodiments, additionally, the resistance between the bonding tool and the pad being connected is detected. In some embodiments, this “pad resistance” is used to determine a part (e.g., a sum part) of the “electrode resistance” (the resistance detected between the bonding tool and the electrode), which part is associated with the temperature of the flexible circuit strip and is independent of the pad. In some embodiments, the pad resistance is monitored during the bonding process, and the two types of resistances detected are used to control the power source of the heating element. Alternatively, in some embodiments, the pad resistance is detected during the data collection process, e.g., as described above with respect to determining the threshold. Wherein, in some embodiments, two types of resistances are used to determine the threshold, but the threshold itself only corresponds to the electrode resistance.

[0032] One aspect of some embodiments of the present disclosure relates to identifying when a sufficient quality electrical and / or mechanical connection has been established between the pad and the wire. Wherein, upon identification, the heating of the bonding tool can be stopped. The potential advantages of accurately and / or early identifying the establishment of a good enough connection can shorten the heating time and / or reduce the heating temperature.

[0033] In some embodiments, a decrease in resistance is identified based on one or both of the pad resistance and the electrode resistance. Wherein the decrease is associated with, for example, the establishment of the connection rather than with cooling. For example, wherein, in some embodiments, the decrease is identified during the power source pulse of the heating element of the bonding tool.

[0034] Alternatively or in addition, in some embodiments, the initial resistance (pad and / or electrode) detected before the initial activation 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. Wherein a decrease in resistance is identified in this comparison. In some embodiments, if the decrease is insufficient, the bonding process can be repeated, e.g., to improve the mechanical and / or electrical connection quality.

[0035] Before detailing at least one embodiment of the invention, it should be understood that the invention is not necessarily limited in its application to the details of the construction and arrangement of the components and / or methods set forth in the following description and / or shown in the drawings and / or examples. The invention is capable of having other embodiments, or of being practiced or carried out in various ways.

[0036] Exemplary Catheter

[0037] Figure 1A is a schematic diagram of a basket catheter 111 according to some embodiments of the present disclosure.

[0038] 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 push rod 118. The optional push rod 118 is configured to be advanced and retracted through the deflectable element 112, for example, using a manipulator or a handle (not shown). The basket catheter 111 also includes an expandable assembly 122 that includes a plurality of flexible circuit strips 124 (only some of the flexible polymer circuit strips are labeled for simplicity), also referred to herein as "flex splines". In some embodiments, the flexible circuit strips 124 are polymer circuit strips. Each flexible circuit strip 124 includes a plurality of electrodes 126 disposed thereon (only some are labeled for simplicity). The formation of the various elements and how they are connected to each other are described in more detail in U.S. Patent Application Publication No. US2021 / 0187241.

[0039] In some embodiments, the form and / or structure of the basket catheter 111 is provided by a basket structure that, in some embodiments, comprises nitinol (e.g., formed of nitinol), such as including a plurality of nitinol strips (also referred to herein as "splines"). 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 together, for example, at the proximal end of the basket catheter 111. The flexible circuit strips 124 can be mounted to the nitinol basket structure before or after establishing an electrical connection with the pads (e.g., Figure 1B the pads 110) of the flexible circuit strips 124. In some embodiments, the electrical connection with the pads 110 of the flexible circuit strips 124 is established before or after connecting the flexible circuit strips to the nitinol support structure, when the flexible circuit strips 124 are in a flat and / or undisconnected configuration (e.g., Figure 1B the configuration shown in

[0040] Exemplary Flexible Circuit Strip Embodiments

[0041] Figure 1B is a top view of the flexible polymer circuit strips 124 of a basket catheter for Figure 1A before assembly.

[0042] Now refer to Figure 1B which is a schematic diagram of the flexible polymer circuit strips 124 in the basket catheter 111 for Figure 1A . The flexible polymer circuit strips 124 can be formed from a single piece of polymer such as polyimide. The circuit strips 124 can be connected to each other by polyimide or assembled to maintain proper alignment and fixed to Figure 1AIndividual pieces of the connector 116. By fabricating the circuit strip 124 as an individual component, the yield of the base circuit can be increased because a failed electrode scrapes one circuit strip rather than the entire strip assembly. The corresponding first end 142 of the corresponding flexible polymer circuit strip 124 includes an electrical connection array 160.

[0043] Illustration 162 shows that the electrical connection array 160 includes pads 110 thereon (only some are labeled for simplicity). The pads 110 are connected via traces (not shown) optionally located on the back of the flexible polymer circuit strip 124 to the corresponding electrodes among the electrodes 126 disposed on the front of the flexible circuit strip 124. In a region away from the first end 142, the flexible circuit strips 124 are separated from each other to allow the flexible circuit strips 124 to form an expandable assembly 122 when connected to the basket catheter 111 ( Figure 1A ). Wires (not shown) can connect the electrodes 126 to a control circuit (not shown) via the pads 110. The wires can be disposed in the lumen (not shown) of the elongate deflectable element 112 ( Figure 1A ).

[0044] 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 (e.g., 30 mm), the width of the flexible circuit strip 124 can be in the range of 0.25 mm to 3 mm (e.g., 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.

[0045] In some embodiments, the electrodes 126 extend to occupy most of the width of the flexible circuit strip 124 that houses them. Among them, in some embodiments, the electrode width 192 is 0.25 mm to 3 mm, and / or the electrode length 190 is 0.25 mm to 3 mm.

[0046] In some embodiments, the size of one or more pads is smaller than the size of the electrodes. Among them, the surface area presented by the pads for contact (e.g., contact with a measurement probe or a bonding tool) is smaller than the surface area presented by the electrodes. For example, the pad upper surface area is 1% to 20% of the electrode surface area. For example, the pad width 194 is 0.05 mm to 0.5 mm, and / or the pad length 196 is 0.1 mm to 1 mm.

[0047] 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 this area can be high. For example, the area having a width 178 of 0.25 mm to 3 mm and a length 198 of 0.5 mm to 6 mm and / or the proportion of the surface area occupied by the pads is 20% to 50%.

[0048] Exemplary Electrical Connection System

[0049] Figure 2 is a simplified 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.

[0050] In some embodiments, the flexible circuit strip 124 is part of a catheter, such as having one or more features as shown and / or described for the catheter 111 with respect to Figure 1A wherein, in some embodiments, the flexible circuit strip 124 corresponds to one or more (e.g., each) of the flexible circuit strips of Figure 1A and / or Figure 1B the flexible circuit strip 124.

[0051] In some embodiments, the system 200 includes a bonding tool 216 configured to bond an electrical connector (e.g., a wire (not shown)) to each pad 110 (e.g., one pad at a time). In some embodiments, the bonding tool 216 is a thermal bonding tool that bonds by generating heat and supplying the heat to the objects to be bonded (e.g., a soldering iron or a soldering gun or an ultrasonic bonding tool).

[0052] In some embodiments, the system 200 includes one or more sensors 220, wherein the sensors 220 are resistance sensors. In some embodiments, the resistance sensor 220 detects the resistance between the bonding tool 216 and an electrode (e.g., the electrode 126a as shown in Figure 2 ). In some embodiments, a probe 242 is used to provide electrical contact with the electrode. Optionally, (not shown) in some embodiments, the resistance between the bonding tool 216 and the pad 210a is directly detected, for example, by contacting the pad.

[0053] In Figure 2 wherein, in some embodiments, the electrical connection (e.g., for resistance detection) is shown by solid lines, and the data connection (e.g., the transmission of the detected resistance level to the controller 218) is shown by dashed arrows.

[0054] In some embodiments, the bonding tool 216 is controlled by a controller 218 that receives sensor signals from one or more sensors. The sensors are, for example, from one or more of the resistance sensors 220.

[0055] In some embodiments, the controller 218 generates a control signal for activating the engagement tool 216, for example, based on a detected resistance level (e.g., from the sensor 220). In some embodiments, the controller 218 generates a control signal and sends the control signal to the power source 226 of the engagement tool 216, where the control signal controls the power supplied by the power source to the heating element 208. Alternatively or in addition, in some embodiments, the controller 218 generates a control signal that is converted (e.g., by the engagement tool) by a processor into a control signal for the power source 226.

[0056] In some embodiments, the power source 226 is configured to supply power pulses 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.

[0057] Optionally, in some embodiments, the system 200 includes one or more temperature sensors (not shown). For example, the engagement tool may include a temperature sensor that can provide a temperature feedback measurement to the controller 218 for controlling the temperature of the engagement tool.

[0058] In some embodiments, the system 200 includes a rigid support (not shown) that provides mechanical support to the flexible circuit strip 124, thereby enabling the engagement tool 216 to apply pressure to the pad, for example, during the engagement process.

[0059] In some embodiments, the flexible circuit strip 124 has at least one (e.g., a plurality of) electrodes 126. The electrodes 126 may be disposed on the distal portion 206 of the flexible circuit strip 124. The electrodes 126 may be disposed on the outer surface of the flexible circuit strip 124. For example, one or more of the electrodes 126 may protrude from a generally flat outer surface (e.g., the top surface) of the flexible circuit strip 124, and / or one or more of the electrodes 126 may have an electrode top surface that is flush with (or recessed from) the top surface of the flexible circuit strip 124.

[0060] In some embodiments, a plurality of pads 110 are disposed on the proximal portion 228 of the flexible circuit strip 124. In some embodiments, one or more of the electrodes 126 (e.g., each electrode) is electrically connected to a corresponding pad of the plurality of pads 110. For example, each electrode is electrically connected to the pad through a separate trace 212, the flexible circuit strip 124 including a plurality of traces 212. In some embodiments, the electrical connection (e.g., a trace or a wire) extends through the body 214 of the flexible circuit strip 124.

[0061] In some embodiments, the flexible circuit strip 124 includes multiple layers, where, for example, the wire 212 that connects the pad 110 to the electrode 126 is sandwiched between at least two layers. Among them, in some embodiments, the outer surface 252 of the flexible circuit strip 124 (also referred to herein as the "top surface" 252) houses the pad 110 and the electrode 126. In some embodiments, the top surface 252 includes an electrically insulating material (e.g., the portions that are not the pad or the electrode are formed of a polymer).

[0062] Alternatively or in addition, in some embodiments, traces are provided on the rear surface 254 of the flexible circuit strip, where, for example, connectors extend through the body 214 to connect the pads and the electrodes to the corresponding traces. Among them, in some embodiments, the rear surface 254 is a surface of the body 214 that is generally opposite to the top surface 252.

[0063] In some embodiments, the bonding tool 216 is capable of automatically moving relative to the flexible circuit strip 124 (e.g., by one or more actuators) for moving the bonding tool between the positions of the multiple pads. Among them, in some embodiments, one or both of the bonding tool 216 and the support on which the flexible circuit strip is disposed are capable of moving 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.

[0064] In some embodiments, the bonding tool tip 238 includes an outer surface, such as a covering including a highly conductive and / or thermally conductive and / or heat-resistant material. For example, the bonding tool includes a covering that is configured to cover (e.g., surround) at least a portion of the bonding tool 216 between the electrical contact regions between the resistance sensor 220 and the bonding tool 216. In some embodiments, the resistive and / or capacitive characteristics of the bonding tool (e.g., as associated with high conductivity and / or thermal conductivity) have a low dependence on temperature.

[0065] In some embodiments, at least a portion of the bonding tool that contacts the pad during the establishment of the connection with the pad (e.g., the tip 238 and / or a portion of the tip) has no adhesiveness to the material of the pad 110. For example, at the temperature employed during the establishment of the connection with the pad. When the bonding tool is a soldering iron, the material of the bonding tool that contacts the solder can have no adhesiveness to the solder, for example, alternatively or in addition, no adhesiveness to the pad surface.

[0066] In some embodiments, the bonding tool tip and / or the covering of the bonding tool and / or the region in the circuit path between the bonding tool and the sensor 208 contain gold (e.g., are formed of gold).

[0067] In some embodiments, user instructions (e.g., to initiate a bonding process) are received via one or more user interfaces (UIs) 236 and / or information is forwarded to the user. In some embodiments, data is transmitted between the UI 236 and the controller 218. For example, in some embodiments, user instructions are transmitted by the UI 236 to the controller 218, which 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 remote.

[0068] Optionally, in some embodiments, an 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.

[0069] Exemplary Electrical Connection Method

[0070] Figure 3A is a method for establishing a connection with a workpiece according to some embodiments of the present disclosure.

[0071] At 304, in some embodiments, the resistance between the bonding tool and the electrode is detected.

[0072] At 306, in some embodiments, the activation and / or temperature of the bonding tool is controlled based on the detected resistance level. In an exemplary embodiment, the activation of the bonding tool is controlled by controlling the power supplied to the heating element of the bonding tool.

[0073] In some embodiments, the heating of the bonding tool during the bonding process is discontinuous. For example, the power source of the heating element is a pulsed power source (e.g., including voltage pulses).

[0074] In some embodiments, the detected resistance is used to control one or more characteristics of the pulsed power source. For example, the characteristics include one or more of pulse duration (width), amplitude, and time pattern (e.g., frequency). In some embodiments, the pulsed power source of the heating element is controlled by pulse width modulation (PWM). In some embodiments, the resistance is detected during the bonding process, thereby providing feedback for the control of the power source of the heating element, e.g., during the bonding process.

[0075] In some embodiments, the control is to keep the resistance below an upper threshold resistance, e.g., where the threshold is associated with the flexible circuit strip reaching a damage temperature.

[0076] Optionally, in some embodiments, the control is to ensure the quality of the bonding process (e.g., the quality of heating). Wherein, if the quality of heating is identified as low, the power supply is increased (e.g., voltage, e.g., the amplitude of the voltage pulse to the heating element). In some embodiments, the quality of the bonding process is ensured by keeping the resistance above a lower threshold resistance, e.g., where the threshold is associated with the temperature when the bonding process is efficient and / or effective. Alternatively or in addition, in some embodiments, the quality of the bonding process is ensured by keeping the rate of change of resistance above a threshold rate during heating (e.g., during the power source pulse).

[0077] In some embodiments, the threshold is received, for example, from a memory (e.g., of circuit 234). In some embodiments, the threshold is provided by a user, e.g., via a user interface. In some embodiments, the threshold is determined by detecting the resistance while heating the flexible circuit strip to different temperatures. For example, the resistance levels of multiple flexible circuit strips and / or their electrodes and pads are detected at different flexible circuit strip temperatures. In some embodiments, an average value is used to determine the threshold.

[0078] Figure 3B is a method for establishing a connection with a workpiece according to some embodiments of the present disclosure.

[0079] At 301, in some embodiments, a resistance measurement circuit is set up. For example, where the measurement probe is in contact with the electrode corresponding to the pad (e.g., probe 242, electrode 126a, and pad 210a, Figure 2 ). In some embodiments, the resistance measurement circuit has a fixed position, e.g., the connection to the electrode for determining the resistance provided by a fixture, where, for example, the flexible circuit strip for the electrical connection process is positioned and the resistance measurement circuit is set up.

[0080] At 303, in some embodiments, the tip of the bonding tool (e.g., Figure 2 the tip 238 of the bonding tool 216) is brought close to (e.g., in contact with) the pad and / or the wire to be connected to the pad and / or solder (e.g., where the bonding tool is a soldering iron). In some embodiments, it is close enough to conduct sufficient heat from the bonding tool to the pad and / or wire and / or solder for the connection process, e.g., the melting of the solder and / or pad and / or wire material. In some embodiments, the positioning of the bonding tool is an automated process, e.g., where one or more actuators controlled by a controller (e.g., Figure 2 the controller 218) are configured to move the bonding tool relative to the flexible circuit strip.

[0081] At 305, in some embodiments, the electrode resistance is monitored. For example, according to Figure 3AOne or more features of step 300.

[0082] At 307, optionally, in some embodiments, additionally monitor the resistance between the bonding tool and the pad being 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) that is associated with the temperature of the trace and the electrode and is independent of the pad, e.g., indicating the temperature of the flexible circuit strip.

[0083] In some embodiments, two resistances are monitored during the bonding process and are used to control the power source of the heating element.

[0084] Alternatively, in some embodiments, the pad resistance is detected during the data collection process, e.g., as described in step 302 of determining the threshold. In some embodiments, the threshold is determined from the data collection of the two types of resistances detected, but the detected electrode resistance level is used during the bonding process (e.g., only used).

[0085] At 309, optionally, in some embodiments, the detected electrode and / or pad resistance is used to identify the contact between the bonding tool and the pad and / or verify that the quality of the contact is sufficient. Wherein, in some embodiments, the contact is identified as a detected resistance drop (e.g., the slope of the resistance drop is higher than the threshold) and / or is identified as the detected resistance dropping below the threshold.

[0086] If the contact and / or the quality of the contact is not verified (e.g., the detected resistance is higher than the threshold), the tip can be repositioned, e.g., returning to step 303. Wherein, for example, the tip can be moved towards the pad, e.g., to increase the pressure between the pad and the tip, thereby improving the electrical and / or thermal contact between them.

[0087] At 311, in some embodiments, the detected resistance is used to control the heating of the tip of the bonding tool. The electrode resistance can be used, e.g., according to Figure 3A One or more features of step 302 of

[0088] At 313, in some embodiments, the detected resistance is used to evaluate the connection quality between the wire and the pad. 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 may be associated with the establishment of an electrical connection, for example, rather than with cooling. For example, in some embodiments, this decrease is identified during a power source pulse of the heating element of the bonding tool. In some embodiments, this decrease is identified when the solder and / or wire forms part of the circuit for which the resistance is being detected. Without wishing to be bound by theory, theoretically, the melting of the solder and / or wire onto the pad, for example associated with improving the electrical connection therebetween, reduces the resistance from the bonding tool through the pad.

[0089] Optionally, in some embodiments, upon identification, heating of the bonding tool can be stopped. The potential advantage of accurate and / or early identification of a sufficiently good connection can shorten the heating time and / or reduce the heating temperature.

[0090] Alternatively or in addition, in some embodiments, the initial resistance (pad and / or electrode) detected at the initial temperature and before activation 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. A decrease in resistance is identified in this comparison. In some embodiments, if the decrease is insufficient, the bonding process can be repeated, for example to improve the mechanical and / or electrical connection quality.

[0091] Figure 4 is a simplified schematic graph of the change in resistance over time according to some embodiments of the present disclosure.

[0092] In some embodiments, Figure 4 shows the resistance detected between the bonding tool (e.g., bonding tool 216) and the pad (e.g., pad 210a) to which the bonding tool is establishing a connection. The resistance can be detected at the electrode as the "electrode resistance".

[0093] Where initially at 400, before the bonding tool contacts the pad, the detected resistance is high, for example, associated with the electrical insulating material (e.g., air) between the bonding tool and the pad.

[0094] When the bonding tool approaches the pad, the detected resistance can decrease at 401 until contact is formed between the pad and the bonding tool at 402. One or both of the slope of the decrease 401 and the detected lower resistance (e.g., below a threshold resistance and / or a proportion of the detected initial resistance) are used to identify and / or verify the contact between the bonding tool and the pad.

[0095] During time period 404, heating the bonding tool can increase the detected resistance, which increase is associated with, for example, an increase in the temperature of the flexible circuit strip. In some embodiments, for example, as described in the methods of Figure 3A and / or Figure 3B , the heating of the bonding tool can be controlled during time period 404, for example, to keep the resistance R below a threshold.

[0096] In some embodiments, when a connection is established, the resistance R may decrease. In some embodiments, the desired resistance decrease (e.g., as shown at 406) is associated with the establishment of a good solder connection. In some embodiments, once the desired resistance decrease is identified, the heating of the bonding tool is stopped. Wherein, in some embodiments, a peak resistance is identified, the value of which is used to determine the desired decrease, which can be a proportion of a given resistance or 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.

[0097] In some embodiments, the final resistance detected at 408 after heating (and optionally cooling) is used to evaluate the quality of the connection. Wherein, in some embodiments, when the detected resistance is below a threshold and / or below a proportion and / or value of the resistance detected before performing the thermal bonding process at 402, the quality of the connection is verified.

[0098] Figures 5A to 5E is a simplified schematic diagram showing the establishment of an electrical connection with pad 210a using bonding tool 216 according to some embodiments of the present disclosure.

[0099] Wherein, in some embodiments, Figures 5A to 5E shows a portion of the flexible circuit strip 124, such as the same portion during the establishment of the electrical connection with pad 210a. In some embodiments, the higher temperature and / or heating is shown by shading in Figures 5A to 5E .

[0100] Now referring to Figure 5A , in some embodiments, the bonding tool 216 (e.g., the tip of the bonding tool) is brought into contact with pad 210a and / or with the wire 550 that contacts pad 210a. Then the bonding tool is heated, for example, as shown by the shading of the bonding tool 216 in Figure 5A . In Figure 5B , the heat from the bonding tool 216 has conducted to the wire 550, thereby raising the temperature of the wire 550. In some embodiments, the heating of the wire 550 is sufficient to connect the wire to the pad via soldering.

[0101] In some embodiments, the bonding tool 216 is continuously heated, for example, as shown in Figure 5CAs shown, heat has been conducted to pad 210a, thereby raising the temperature of the pad. In some embodiments, heating both the wire and the pad is sufficient to connect the wire to the pad via soldering.

[0102] In some embodiments, the bonding tool 216 is a soldering iron. One or both of the pad and the wire may include solder and / or the solder may be positioned to contact 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. Heating the bonding tool may then melt the solder to connect the pad and the wire.

[0103] Now referring to Figure 5D , heat has been conducted from pad 210a to the upper portion 552 of the flexible circuit strip 124, thereby raising its temperature. With continued heating, the temperature rise of the upper layer of the flexible circuit strip 124 (e.g., adjacent to portion 552) can extend to the pad adjacent to pad 210a.

[0104] In some embodiments, this situation is avoided and / or the temperature of the flexible circuit strip is maintained at a temperature at which the flexible circuit strip 124 is not damaged due to erratic (e.g., switching) heating by the bonding tool. Switching potentially prevents overheating of the flexible circuit strip material, which is thermally insulating (e.g., as opposed to the pad material). For example, before reaching the situation shown in Figure 5D , the heating of the bonding tool is stopped, for example, by cutting the power to the heating element of the bonding tool, as shown in Figure 5E . In some embodiments, the bonding tool may be repeatedly heated (e.g., cycled) to heat the wire 550 and / or pad 210a to a temperature associated with a good quality connection without damaging the flexible circuit strip.

[0105] General

[0106] As used within this document, the term "about" means ±20%.

[0107] The terms "comprising," "containing," "including," "having," and variations thereof mean "including but not limited to."

[0108] The term "consisting of" means "including and limited to."

[0109] As used herein, unless the context clearly dictates otherwise, singular forms such as "a," "an," and "the" include plural referents.

[0110] In 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, a description that includes a range should be considered to have specifically disclosed all possible sub-ranges as well as individual values within that range. 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, etc., as well as individual values within the stated range and / or sub-ranges, such as 1, 2, 3, 4, 5, and 6. Whenever a numerical range is indicated in this document, it is meant to include any recited number (fractional or integer) within the indicated range.

[0111] It should be understood that, for clarity, certain features described in the context of separate embodiments may also be provided in combination in a single embodiment. The various features of the present disclosure described in the context of a single embodiment (e.g., for simplicity) may also be provided separately or in any suitable sub-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 unless the embodiment does not function without those elements.

[0112] Although the present disclosure has been described in connection with its specific embodiments, it is apparent that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, this application is intended to cover all such alternative forms, modifications, and variations that fall within the spirit and broad scope of the appended claims.

[0113] All references mentioned in this specification (e.g., publications, patents, and patent applications) are hereby incorporated by reference in their entirety into this specification, for example, as if each individual publication, patent, or patent application were specifically and individually indicated to be incorporated by reference herein. 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. Additionally, any priority documents and / or documents related to this application (e.g., co-filed documents) are hereby incorporated by reference in their entirety into this text.

[0114] When section headings are used in this document, they should not be construed as necessarily limiting.

[0115] General Description

[0116] The following is a non-exclusive list of some exemplary embodiments of the present disclosure. The present disclosure also includes embodiments that contain less than all of the features in the examples and embodiments that use features from multiple examples, even if not listed below.

[0117] 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), wherein the flexible circuit strip includes 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:

[0118] Positioning the bonding tool (216) near the connection pad (210a) of the plurality of connection pads (110) and the wire (550) to be connected to the connection pad (210a);

[0119] Activating 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);

[0120] During the activation, monitoring the resistance between the bonding tool (216) and the electrode (126a) electrically connected to the connection pad (210a), the resistance indicating the temperature of the flexible circuit strip (124); and

[0121] Controlling the activation to keep the resistance below an upper threshold associated with the flexible circuit strip (124) reaching a damage temperature.

[0122] Example 2. The method according to Example 1, wherein the activation includes supplying a plurality of electrical pulses to one or more heating elements of the bonding tool.

[0123] 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.

[0124] Example 4. The method according to any one of Examples 2 to 3, wherein the control includes controlling one or more characteristics of the plurality of electrical pulses.

[0125] Example 5. The method according to Example 4, wherein the one or more characteristics of the plurality of electrical pulses include one or more of the following:

[0126] Pulse duration, pulse repetition frequency, and pulse amplitude.

[0127] Example 6. The method according to Example 4, wherein the controlling the one or more characteristics of the plurality of electrical pulses includes pulse width modulation (PWM) of an activation signal of the bonding tool (216).

[0128] Example 7. The method according to any one of Examples 1 to 4, wherein the control includes maintaining the resistance above a lower threshold value.

[0129] Example 8. The method according to any one of Examples 2 to 7, including determining a rate of change of the resistance;

[0130] wherein the control is using the rate of change.

[0131] Example 9. The method according to Example 8, wherein the determining includes determining that the rate of change of the resistance is below a threshold; and

[0132] wherein the control includes increasing an amplitude of the electric power pulse.

[0133] Example 10. The method according to any one of Examples 2 to 9, wherein the control includes:

[0134] identifying a portion of the resistance associated with a connection between the wire (550) and the connection pad (210a); and

[0135] detecting a decrease in the portion of the resistance.

[0136] Example 11. The method according to Example 10, including deactivating the bonding tool (216) when detecting the decrease in the portion of the resistance.

[0137] Example 12. The method according to Example 11, wherein the detecting the decrease in the resistance occurs during the supply of a pulse of the plurality of electric pulses.

[0138] Example 13. The method according to claim 10, including:

[0139] storing an initial measurement of the resistance before the activation when the flexible strip is at an initial temperature;

[0140] deactivating the bonding tool (216); and

[0141] wherein the detecting the decrease in the resistance includes comparing the initial measurement of the resistance with the resistance after the flexible strip has cooled to the initial temperature.

[0142] Example 14. The method according to any one of Examples 10 to 13, including evaluating a connection quality between the wire (550) and the connection pad (210a) based on the decrease in the resistance.

[0143] Example 15. The method according to Example 14, wherein the quality is one or more of a thermal connection, an electrical connection, and a mechanical connection between the wire and the connection pad.

[0144] Example 16. The method according to any one of Examples 14 to 15, including repeating the activation based on the evaluation.

[0145] 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.

[0146] Example 18. A system for electrically connecting a wire (550) to a connection pad (210a) of a flexible circuit strip (124), 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 system comprising:

[0147] A thermo-bonding tool (216), the thermo-bonding tool including one or more heating elements;

[0148] A sensor (220), the sensor being configured to measure a resistance between the bonding tool (216) and an electrode (126a) electrically connected to the connection pad (210a) among the plurality of connection pads (110), the resistance indicating a temperature of the flexible circuit strip (124);

[0149] A controller (218), the controller being configured to:

[0150] Receive the measurement of the resistance from the sensor (220); and

[0151] Control the activation of the one or more heating elements to heat a tip (238) of the bonding tool (216) for connecting the connection pad (210a) and the wire (550) near the tip (238), while keeping the resistance below an upper threshold associated with reaching a damage temperature of the flexible circuit strip (124).

[0152] Example 19. A controller (218) for controlling the electrical connection of a wire (550) to a connection pad (210a) of a flexible circuit strip (124) using a thermo-compression bonding tool (216), wherein the flexible circuit strip (124) includes a polymer body (214), a plurality of electrodes (126), a plurality of connection pads (110), and a plurality of conductive traces (212) that connect each of the plurality of electrodes (126) to a connection pad of the plurality of connection pads (110), and the controller (218) includes circuitry configured to:

[0153] Activate the bonding tool to heat the tip (238) of the bonding tool (216) to electrically connect the wire (550) to the connection pad (110a);

[0154] During the activation, measure 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); and

[0155] Control the activation of the bonding to keep the resistance below an upper threshold associated with the flexible circuit strip (124) reaching a damage temperature.

Claims

1. A system for electrically connecting a conductor to a connection pad of a flexible circuit strip, the flexible circuit strip comprising a polymer body, a plurality of electrodes, a plurality of connection pads, and a plurality of conductive traces connecting each of the plurality of electrodes to a connection pad of the plurality of connection pads, the system comprising: 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; A controller, the controller being configured to: receiving a measurement of the resistance from the sensor; as well as Activation of the one or more heating elements is controlled to heat a tip of the bonding tool for connecting the connection pad and the wire near the tip while maintaining the resistance below an upper threshold associated with the flexible circuit strip reaching a damage temperature.

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

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

4. A system according to any one of claims 2 to 3, wherein: The controller is configured to control one or more characteristics of the plurality of electrical pulses.

5. The system according to claim 4, wherein: The one or more characteristics of the plurality of electrical pulses include one or more of: pulse duration, pulse repetition frequency, and pulse amplitude.

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

7. A system according to any one of claims 1 to 6, wherein: The controller is configured to maintain the resistance above a lower threshold.

8. A system according to any one of claims 2 to 7, wherein: The controller is configured to: determining a rate of change of the resistance; The rate of change of the resistance is used to control the activation of the one or more heating elements.

9. The system according to claim 8, wherein: The controller is configured to: determining that the rate of change of the resistance is below a threshold; and The activation is controlled by increasing the amplitude of the plurality of electrical power pulses.

10. The system according to any one of claims 2 to 9, wherein: The controller is configured as: identifying a portion of the resistance associated with a connection between the conductive line and the connection pad; detecting a drop in said portion of said resistance; as well as The bonding tool is deactivated when the drop in the portion of the resistance is detected.

11. The system according to claim 10, wherein: The controller is configured to detect the drop in the electrical resistance occurring during the supplying of pulses of the plurality of electrical pulses.

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

13. A system according to any one of claims 10 to 12, wherein: The controller is configured to evaluate a quality of connection between the conductive line and the connection pad based on the drop in the resistance.

14. The system according to claim 13, wherein: The controller is configured to one or more of the following: repeatedly activating the one or more heating elements based on the quality of the connection; and One or more characteristics of the supplying of the plurality of electrical pulses are adjusted based on the connection quality.

15. A method of electrically connecting a conductor to a connection pad of a flexible circuit strip using a thermal bonding tool, wherein: The flexible circuit strip includes a polymer body, a plurality of electrodes, a plurality of connection pads, and a plurality of conductive 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 near a connection pad among the plurality of connection pads and the wire to be 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; During the activation, monitoring a resistance between the bonding tool and an electrode electrically connected to the connection pad, the resistance being indicative of a temperature of the flexible circuit strip; and The activation is controlled to maintain the resistance below an upper threshold associated with the flexible circuit strip reaching a damage temperature.

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