Reworkable Adhesive Composition for Electronics Repair
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Solution Overview
Problem
Structural adhesives in electronics face challenges due to their rigidity, leading to uneven stress and damage upon removal, which limits their reworkability and repairability, particularly in applications like display screens where expensive components are at risk.
Innovation Solution
A reworkable adhesive composition featuring a linear triblock copolymer with high and low glass transition temperature subunits, dissolved in a monomer solution and cured with a free radical initiator, allowing for fast curing and subsequent removal or repair at elevated temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If structural adhesives are used to provide strong bonding and barrier protection, then bond strength and durability are improved, but rigidity causes uneven stress and substrate damage upon removal
Solution Approach 1:
The patent applies parameter changes by utilizing temperature as a control variable. The adhesive composition is designed to cure at elevated temperatures (70-150°C) to achieve strong bond strength, but then becomes removable through heating to even higher temperatures (100-200°C). This temporal separation of curing temperature and removal temperature resolves the contradiction between achieving strong bonds and enabling easy removal/repair.
Solution Approach 2:
The adhesive composition exhibits dynamic properties that change with temperature. At curing temperatures, the adhesive forms a rigid, strong bond. At removal temperatures, the adhesive becomes more flexible and removable. This dynamic behavior allows the same material to provide both strong bonding and easy repairability at different stages of the service life.
2Reliability
If rigid structural adhesives are used for high temperature performance and durability, then bond integrity is improved, but component damage and stress unevenness increase
Solution Approach 1:
The adhesive composition is designed with built-in stress management capabilities from the outset. The formulation includes flexible segments that preliminarily accommodate stress during curing, and the crosslink density is controlled to allow subsequent thermal removal without causing damage. This preliminary design consideration prevents stress damage while maintaining durability.
Solution Approach 2:
The patent uses temperature parameter changes to differentiate between the curing phase (where rigidity and durability are achieved) and the removal phase (where flexibility and stress relief are enabled). By separating these thermal processes, the adhesive maintains high reliability during service while enabling damage-free removal when needed.
3Productivity
If fast curing is achieved using peroxide initiators and acid chlorides, then productivity is improved, but control over cure timing and reworkability becomes more difficult
Solution Approach 1:
The patent introduces an intermediary substance - a specific crosslinker - that mediates between the fast-curing initiators and the desired reworkability. The crosslinker reacts with the peroxide initiator to form a controlled crosslinking network that provides fast curing productivity while maintaining the ability to remove and rework the bond through thermal processing. This intermediary component decouples the conflict between cure speed and reworkability control.
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
The adhesive composition provides structural performance with reworkability, maintaining bond integrity and allowing for clean removal and repair of components, ensuring high bond retention and durability in various substrates, including electronics, with improved stress resistance and flexibility.
Implementation Method 1
curable under free radical polymerization
Implementation Method 2
By heating the cured adhesive to 70°C and above, the adhesive is amenable to being removed, repaired, or reworked
Implementation Method 3
a linear triblock block copolymer present at greater than or equal to 30 total weight percent comprising high glass transition temperature subunits Y and Y'
Data Source
AI summary
An adhesive composition is provided that includes a block copolymer present at greater than or equal to 30 total weight percent of the adhesive system comprising a high glass transition temperature in subunits Y and Y', each of the subunits Y and Y' having a high glass transition temperature of from 70°C to 130CC with a low glass transition temperature subunit Z having a low glass transition temperature of from -100CC to 10°C intermediate between said high glass transition temperature acrylate subunits to define a structure Y-Z-Y'. The triblock copolymer is dissolved in a monomer curable under free radical. A free radical initiator of a peroxide or a hydroperoxide are present in combination with a sulfonyl chloride, dihydropyridine and copper or vanadium salt. By heating the cured adhesive at or above 70°C, the adhesive is amenable to being removed, repaired, or reworked.