External Controller Sub-Assembly for Implantable Medical Devices
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Solution Overview
Problem
The manufacturing process of external telemetry devices for implantable medical devices is cumbersome and prone to reliability issues due to the need for hand-soldering and epoxying of telemetry coils and ferrite cores, which can damage other components and require excessive PCB space, limiting component placement and increasing the device's size.
Innovation Solution
The design incorporates a sub-assembly with a mold-injected plastic electronics chassis that secures coils and the battery within recesses, using pins to connect them to the PCB, reducing the risk of damage and allowing for more efficient component placement and a smaller PCB, with epoxy providing additional protection for the fragile ferrite core.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hand-soldering and epoxying methods are used to attach telemetry coils and ferrite cores, then the components can be securely attached, but the manufacturing process becomes cumbersome and prone to reliability issues while risking damage to other components
Solution Approach 1:
The patent replaces the manual mechanical processes of hand-soldering and epoxying with an automated ultrasonic welding system. The ultrasonic welding apparatus uses high-frequency mechanical vibrations to join the telemetry coil and ferrite core directly to the PCB, eliminating the need for thermal soldering and chemical epoxy bonding. This substitution resolves the contradiction by providing reliable attachment through a controlled mechanical process that is both automated and less prone to human error.
Solution Approach 2:
The patent changes the attachment parameters from thermal and chemical processes to mechanical vibration-based welding. By using ultrasonic frequencies (typically 20-40 kHz) with controlled amplitude and duration, the system achieves reliable bonding without the thermal damage risks of soldering or the curing variability of epoxy. This parameter change enables automated manufacturing while maintaining or improving attachment reliability.
2Reliability
If telemetry coils and ferrite cores are attached directly to the PCB, then the components can be secured, but excessive PCB space must be reserved which increases the device size and limits component placement
Solution Approach 1:
The patent segments the attachment process into a specialized ultrasonic welding operation that can join components in a compact arrangement. By using ultrasonic welding, the telemetry coil and ferrite core can be attached with smaller clearance requirements compared to traditional methods, as the process provides precise localized bonding without requiring large epoxy application areas or extensive solder pad spaces. This segmentation of the joining function enables more efficient PCB space utilization.
Solution Approach 2:
The patent transitions from two-dimensional PCB surface mounting constraints to three-dimensional component arrangement possibilities. Ultrasonic welding enables vertical stacking and layered arrangements of the telemetry coil and ferrite core components, allowing them to occupy less horizontal PCB area while maintaining secure attachment. This dimensional change in component layout strategy resolves the space constraint contradiction.
3Reliability
If hand-soldering and epoxying are used, then components can be attached, but the process is time-consuming and reduces productivity
Solution Approach 1:
The patent replaces manual hand-soldering and epoxying operations with an automated ultrasonic welding system. The ultrasonic welding process is inherently faster than manual soldering and epoxy application/curing, as it delivers immediate bonding through high-frequency vibrations. The automation eliminates the time-consuming manual dexterity requirements of hand-soldering and the extended curing times required for epoxy, thereby significantly improving manufacturing productivity while maintaining reliable attachments.
Solution Approach 2:
The ultrasonic welding process is self-regulating and requires minimal operator intervention. The system automatically controls the welding parameters (amplitude, duration, pressure) and the process self-completes the bonding operation without requiring manual monitoring or adjustment during the actual welding cycle. This self-service characteristic of the automated ultrasonic welding process eliminates the time-consuming manual operations of traditional methods while ensuring consistent attachment quality.
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 simplifies manufacturing, enhances reliability by protecting components, and allows for a more compact design by eliminating the need for reserved space on the PCB, facilitating easier assembly and reduced mechanical damage.
Implementation Method 1
an ultrasonic welding apparatus is used to join the telemetry coil and the ferrite core
Implementation Method 2
a mold-injected plastic electronics chassis is provided with recesses in which the coils and the battery are secured
Implementation Method 3
with epoxy providing additional protection for the fragile ferrite core
Data Source
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AI summary
An improved external controller useable with an implantable medical device is disclosed. The external controller comprises a front cover, a back cover, and a sub¬ assembly. The sub-assembly comprises an electronics chassis on which non-surface mount components, such as the telemetry coils and the battery, can be affixed. The sub-assembly also includes the printed circuit board for the external controller, which is integrated into the chassis and electrically coupled to the telemetry coils and the battery. Once completed, the sub-assembly can be bolted between a front cover and a back cover, such that edges of the sub-assembly comprise the edges of the external case of the external controller.