ACA Circuit Assembly Channels for Complete FlexIC Bonding
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Solution Overview
Problem
The use of anisotropic conductive adhesive (ACA) to bond flexible circuit structures to application circuits is hindered by issues such as ACA flow impediment, structural damage from conductive particles, and excessive material usage, particularly when application circuits have raised features or require high pressure bonding.
Innovation Solution
Incorporating shield sections or channels in the circuit modules to control ACA flow, provide mechanical support, and minimize conductive particle penetration, while optimizing ACA distribution and reducing material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ACA is applied to bond FlexIC to application circuit, then electrical connection is achieved, but raised features impede ACA flow causing incomplete bonding
Solution Approach 1:
The application circuit conductors are segmented by introducing slots that divide the raised features into separate sections. This segmentation allows ACA to flow through the slots and reach all bonding areas, resolving the incomplete bonding issue caused by continuous raised features blocking ACA flow.
Solution Approach 2:
Slots are introduced as intermediary features within the raised conductor structures. These slots act as channels that mediate ACA flow through the raised features, enabling the adhesive to pass through and achieve complete bonding while maintaining the structural integrity of the conductors.
2Reliability
If ACA is applied generously to ensure complete coverage, then bonding coverage is improved, but material costs increase due to excess ACA usage
Solution Approach 1:
Slots are strategically positioned in specific locations where raised features block ACA flow, rather than uniformly distributing ACA throughout. This localized modification allows ACA to flow through critical blocking points, achieving complete bonding coverage with reduced overall material usage.
3Reliability
If pressure is applied to spread ACA across the interface, then bonding coverage is improved, but conductive particles may penetrate and damage FlexIC
Solution Approach 1:
Slots are pre-introduced into the raised conductor features before the bonding process. This preliminary action creates predetermined flow paths that guide ACA through the raised features, eliminating the need for excessive pressure that would otherwise be required to achieve complete coverage, thereby preventing particle penetration damage to the FlexIC.
4Reliability
If raised features are removed to improve ACA flow, then bonding completeness is improved, but structural integrity of application circuit is compromised
Solution Approach 1:
Rather than removing the raised features entirely, they are segmented by introducing slots that maintain the overall structural integrity of the conductors while creating flow paths for ACA. This segmentation approach preserves mechanical strength while enabling complete bonding coverage.
Solution Approach 2:
The raised conductor features are transformed into porous-like structures with slots that allow ACA to pass through. This creates a permeable pathway system within the conductors that maintains their structural form while enabling complete adhesive penetration and bonding.
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
Enhances bonding efficiency by minimizing ACA volume and cost, reducing structural damage, and ensuring complete coverage without overspill, thus improving the integrity and functionality of flexible circuit assemblies.
Implementation Method 1
anisotropic conductive adhesive (ACA) which comprises a plurality of electrically conductive particles held in a non-conductive, initially fluid, adhesive
Implementation Method 2
The binder cures thermally to secure the bond between the flexible circuit structure and the application circuit
Implementation Method 3
Incorporating slots or channels in shield sections and application circuit conductors to control ACA flow, allowing it to spread across the interface while preventing conductive particles from penetrating the FlexIC
Data Source
AI summary
An electronic circuit assembly comprises: a first electronic circuit module; a second electronic circuit module; and a quantity of anisotropic conductive adhesive, ACA, comprising a plurality of electrically conductive particles and an electrically non-conductive adhesive, arranged to bond the first electronic circuit module to the second electronic circuit module. The first electronic circuit module comprises a first surface and a first pair of electrical contacts each provided on said first surface, the second electronic circuit module comprises a second surface and a second pair of electrical contacts each provided on said second surface, said first surface is arranged to face said second surface, said first pair of electrical contacts is aligned with said second pair of electrical contacts such that a first electrical contact of the first pair opposes a first electrical contact of the second pair and a second electrical contact of the first pair opposes a second electrical contact of the second pair, said quantity of ACA occupies a volume between the first and second surfaces, and conductive particles of the ACA provide a first electrical connection between the first electrical contacts of the first and second pairs, and a second electrical connection between the second electrical contacts of the first and second pairs. The first electronic circuit module further comprises at least one member provided on and protruding from said first surface and arranged between the first pair of electrical contacts, and at least one channel provided through a said member or defined between a plurality of said members, each said channel providing a flow channel, in a direction parallel to the first surface, for at least said non-conductive adhesive during manufacture of the assembly.