Implantable Device Flex Circuit Securement

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Solution Overview

Problem

Existing assembly methods for implantable medical devices, such as defibrillators, face challenges in securely positioning flexible shields or dump resistors within the device, particularly due to the use of encapsulant layers for mechanical, thermal, and electrical protection, which requires precise control to ensure appropriate placement and integration during manufacturing.

Innovation Solution

A method involving the use of a flexible circuit with a tab, where a first encapsulant layer is applied over internal components, and the flexible circuit is secured to this layer, with a second encapsulant layer applied to cover the assembly, and reflowing of the first layer is used to ensure secure attachment, particularly at the outer edge of the flexible circuit, using techniques like laser welding or heat application.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If encapsulant layers are used to provide mechanical, thermal, and electrical protection to components, then reliability and protection are improved, but positioning precision and assembly complexity worsen due to the need for precise control during manufacturing

Engineering Contradiction:

Improvemechanical protectionVSAvoidpositioning precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The flexible circuit is secured to the assembly at a flexible circuit tab before the encapsulant is applied. This preliminary positioning ensures the flexible circuit is in the correct location before the encapsulant is deposited, eliminating the need for precise encapsulant placement and simplifying the manufacturing process while maintaining reliability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The flexible circuit tab acts as an intermediary element that facilitates attachment of the flexible circuit to the assembly. By providing a dedicated attachment point, the tab enables precise positioning without requiring the encapsulant to be precisely controlled, thus resolving the contradiction between protection and positioning precision

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If the flexible circuit is secured after encapsulant deposition, then assembly flexibility is improved, but positioning accuracy and secure attachment worsen

Engineering Contradiction:

Improveassembly flexibilityVSAvoidpositioning accuracy

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The flexible circuit is secured to the assembly at the flexible circuit tab before the encapsulant is applied. This preliminary action ensures accurate positioning is achieved when it matters most, while the subsequent encapsulant deposition provides secure attachment and protection, maintaining both positioning accuracy and assembly flexibility

Inventive Principle:

Principle #10Preliminary action

3Ease of manufacture

If the flexible circuit is not securely attached during processing, then manufacturing simplicity is improved, but flexing issues and reliability worsen

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidflexing control

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The flexible circuit is secured to the assembly at the flexible circuit tab before encapsulant application. This preliminary securing prevents flexing issues during processing without requiring complex manufacturing steps, as the tab provides a simple, effective attachment point that maintains reliability while keeping the manufacturing process straightforward

Inventive Principle:

Principle #10Preliminary action

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 ensures proper positioning and secure attachment of the flexible circuit, preventing flexing issues during processing and manufacturing, while also providing effective electromagnetic interference shielding and energy dissipation, enhancing the reliability and efficiency of the implantable medical device assembly.

Implementation Method 1

reflowing is achieved by applying energy from a laser welder

Methodology Applied

Scientific EffectLaser welding: Laser Beam Welding

Implementation Method 2

reflowing is achieved by applying heat by contact

Methodology Applied

Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 3

The flexible circuit comprises an electromagnetic interference shield

Methodology Applied

Scientific EffectElectromagnetic shielding: Faraday Cage

Implementation Method 4

The flexible circuit comprises a dump resistor for dumping excess energy of the implantable medical device

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS20240325764A1Implantable medical device with flex circuit

Publication Date: 2024.10.03 CARDIAC PACEMAKERS INC

AI summary

Methods of manufacturing an implantable medical device, and devices resulting from such methods. A printed circuit board assembly is made, and a first portion of encapsulant is applied to at least a portion of the printed circuit board assembly. A flex circuit is attached, such as by soldering, to the printed circuit board assembly. The flex circuit is then secured to the first portion of encapsulant, prior to applying a second portion of encapsulant.