Heat Joining Control for Flexible Circuit Wire-to-Pad Connections
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Solution Overview
Problem
The challenge in catheter manufacture is establishing reliable electrical connections to flexible circuit strips with densely packed pads, which are prone to overheating and damage during the heat joining process.
Innovation Solution
The solution involves using a joining tool with a pulsed power supply controlled by resistance feedback to maintain the resistance below a threshold, preventing overheating of the flexible circuit strip and ensuring a high-quality connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous heating is used to establish electrical connections to densely packed pads, then connection reliability is improved, but the flexible circuit strip overheats and suffers damage
Solution Approach 1:
The patent applies periodic heating by using a pulsed power supply that delivers heating power in discrete pulses rather than continuous heating. The controller activates the joining tool in periodic pulses, allowing heat to dissipate between pulses and preventing cumulative overheating of the flexible circuit strip while still achieving reliable electrical connections to densely packed pads.
Solution Approach 2:
The patent implements feedback control by using a measurement probe to detect resistance between the joining tool and an electrode connected to the pad being joined. The controller monitors this resistance in real-time and uses it as feedback to dynamically adjust the heating power delivered by the pulsed power supply, ensuring connections are made reliably while preventing overheating damage to the flexible circuit strip.
2Productivity
If heating power is increased to establish reliable electrical connections quickly, then productivity is improved, but the flexible circuit strip reaches damaging temperatures
Solution Approach 1:
The pulsed power supply delivers heating power in controlled periodic pulses rather than continuous high power, enabling rapid connection establishment while limiting cumulative heat input to prevent the flexible circuit strip from reaching damaging temperatures.
Solution Approach 2:
The real-time resistance measurement and feedback control enable the system to detect when a reliable electrical connection is established and immediately adjust or terminate heating power, achieving fast connections without unnecessary continued heating that would cause temperature damage.
3Manufacturing precision
If heating duration is extended to ensure complete bonding, then connection quality is improved, but heat-sensitive material suffers damage
Solution Approach 1:
The resistance measurement provides real-time feedback on the bonding process, allowing the controller to detect when a complete and reliable electrical connection has been achieved. The heating duration is automatically adjusted based on this feedback, ensuring sufficient heating for complete bonding while preventing excessive heating duration that would damage the heat-sensitive flexible circuit strip material.
Solution Approach 2:
The system dynamically changes heating parameters (power level, pulse duration, pulse frequency) based on real-time resistance measurements and feedback, optimizing the heating process to achieve complete bonding with minimal heating duration, thereby preventing damage to the heat-sensitive flexible circuit strip material.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces the duration and temperature of heating, minimizing damage to the flexible circuit strip and ensuring a reliable, efficient electrical connection.
Implementation Method 1
activating the joining tool to heat a tip of the joining tool to electrically connect the wire to the connection pad
Implementation Method 2
monitoring, during the activating, a resistance between the joining tool and an electrode electrically connected to the connection pad, which resistance indicative of temperature of the flexible circuit strip
Data Source
AI summary
A method of electrically connecting a wire to a connection pad of a flexible circuit strip using a heat joining 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, a trace connecting each of the plurality of electrodes to a connection pad of the plurality of connection pads, the method including: 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 to electrically connect 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, which 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.