Anisotropic Conductive Film Rework via Elastic Modulus Control
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Solution Overview
Problem
Conventional anisotropic conductive films (ACF) face challenges in rework due to strong adhesion, which can damage FPC circuit patterns and require lengthy repair processes, and struggle with heat resistance, making it difficult to achieve high connection reliability.
Innovation Solution
A method for manufacturing a mounting body using an anisotropic conductive film with a binder having an epoxy resin and conductive particles with specific properties, allowing for easy rework and high connection reliability by ensuring conductive particle penetration through cured residue, and achieving a high elastic modulus for improved heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional ACF is used for connecting electronic components, then strong adhesion is achieved, but rework becomes difficult and FPC circuit patterns may be damaged
Solution Approach 1:
The patent applies parameter changes by controlling the elastic modulus of the cured ACF binder within a specific range (10-1000 MPa at 150°C). This optimized parameter range allows the ACF to maintain strong adhesion while enabling easier rework, as the binder becomes sufficiently compliant to allow component removal without damaging the FPC circuit patterns.
Solution Approach 2:
The patent introduces dynamics by making the ACF binder's elastic modulus temperature-dependent. The binder exhibits different mechanical properties at different temperatures: it provides strong adhesion at room temperature but becomes more compliant at elevated temperatures during rework, facilitating component removal while maintaining connection strength during normal operation.
2Reliability
If conventional ACF is used for connecting electronic components, then electrical connection is achieved, but heat resistance and connection reliability are compromised
Solution Approach 1:
The patent applies parameter changes by optimizing the elastic modulus of the binder within a specific range (10-1000 MPa at 150°C) to achieve both strong adhesion and adequate heat resistance. This parameter optimization ensures that the ACF maintains its mechanical integrity and electrical connection reliability under high-temperature and high-humidity conditions while still allowing for rework.
3Ease of repair
If ACF with low elastic modulus is used to facilitate rework, then rework becomes easier, but heat resistance and connection reliability deteriorate
Solution Approach 1:
The patent resolves this contradiction by defining a specific elastic modulus range (10-1000 MPa at 150°C) for the cured ACF binder. This optimized parameter range balances rework ease and connection reliability: the lower bound (10 MPa) ensures sufficient compliance for rework, while the upper bound (1000 MPa) maintains adequate heat resistance and connection strength under operating conditions.
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 method enables simplified rework without damaging wiring boards, ensures reliable conduction, and enhances heat resistance, allowing for high connection reliability even in high-temperature and high-humidity environments.
Implementation Method 1
Thermocompression bonding electrode portions of respective electronic components via ACF enables electrical connection formation in the direction of force application via the conductive particles while maintaining electrical insulation between adjacent electrodes; furthermore, the respective electronic components can be secured so as not to peel apart from one another.
Implementation Method 2
conduction can be ensured by penetration of conductive particles even in the case of cured ACF residue remaining on a reusable wiring board
Implementation Method 3
a binder having an epoxy resin as a primary constituent... a high elastic modulus in the binder after curing improves heat resistance
Data Source
AI summary
A method for manufacturing a mounting body comprising: a mounting step of mounting an electronic component onto a wiring board via an anisotropic conductive film containing a binder having an epoxy resin as a primary constituent and conductive particles having a compressive hardness (K) of 500 kgf / mm2 or more when compressively deformed by 10%, wherein a relation between a thickness (A) of the binder and an average particle diameter (B) is 0.6 ≦ B / A ≦ 1.5 and an elastic modulus of the binder after curing is 50 MPa or more at 100°C; and a remounting step of mechanically peeling to detach the electronic component and the wiring board in the case of a problem occurring in mounting of the mounting step and reusing the wiring board to perform the mounting step.