UV-Curable Silicone PSA Composition for Micro-Transfer Printing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing UV-curable silicone pressure-sensitive adhesive (PSA) compositions for micro-transfer-printing face issues with dimensional accuracy, adhesive migration, and insufficient strength due to the presence of non-crosslinkable resin components, which lead to cohesive failure during material molding and transferring of miniaturized parts.
Innovation Solution
A UV-curable silicone PSA composition comprising organopolysiloxane with specific (meth)acryloyloxy-containing groups, siloxane structure-free monofunctional (meth)acrylate compounds, and organopolysiloxane resin, cured via UV irradiation, eliminating non-crosslinkable resin components and achieving satisfactory adhesion and rubber strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If solventless silicone base PSA compositions of heat cure type are used, then adhesive force is improved, but dimensional accuracy deteriorates due to shrinkage upon cooling
Solution Approach 1:
The patent changes the curing mechanism from thermal curing to UV photopolymerization curing. This parameter change eliminates the heating and cooling cycle that causes shrinkage, thereby maintaining dimensional accuracy while still achieving strong adhesive force through crosslinking of the silicone PSA composition.
Solution Approach 2:
The patent replaces the thermal curing mechanism (heat-based chemical reaction) with UV photopolymerization (light-based chemical reaction). This substitution eliminates the thermal expansion and contraction cycles that cause dimensional errors, while maintaining the crosslinking function necessary for adhesive strength.
2Strength
If non-crosslinkable resin components are included as tackifiers, then pressure-sensitive adhesion is improved, but adhesive migration occurs leaving residue on chips
Solution Approach 1:
The patent removes the non-crosslinkable resin component from the composition entirely. Instead of including a separate tackifier that cannot crosslink, the patent achieves pressure-sensitive adhesion through the crosslinked silicone PSA composition itself, eliminating the source of adhesive migration and residue.
Solution Approach 2:
The patent creates a homogeneous crosslinked network throughout the silicone PSA composition. The crosslinked structure ensures uniform distribution of adhesive properties throughout the material, preventing localized migration of adhesive components to the surface or onto transferred chips.
3Ease of operation
If non-crosslinkable resin components are present, then tackifying function is provided, but cohesive failure occurs during molding and transferring
Solution Approach 1:
The patent extracts and removes the non-crosslinkable resin component that causes weak points in the material. The tackifying function is achieved through the crosslinked silicone PSA composition itself, which provides both initial tack and ultimate cohesive strength, eliminating the risk of cohesive failure during molding and transferring operations.
Solution Approach 2:
The patent creates a composite crosslinked structure within the silicone PSA composition. The crosslinked network provides a reinforced composite material that maintains both the tackifying function needed for picking up chips and the cohesive strength required to withstand molding and transferring forces without failure.
4Loss of time
If UV irradiation curing is used, then curing time is reduced and dimensional accuracy is improved, but adhesive force and rubber strength become insufficient
Solution Approach 1:
The patent changes the chemical composition parameters of the silicone PSA to be compatible with UV photopolymerization curing. By incorporating UV-curable functional groups and appropriate photopolymerization initiators, the composition achieves rapid curing at room temperature while maintaining or enhancing adhesive force and rubber strength through efficient crosslinking.
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 composition effectively suppresses adhesive migration and achieves excellent pressure-sensitive adhesion and rubber strength, preventing cohesive failure and ensuring accurate transfer of miniaturized parts with improved dimensional accuracy.
Implementation Method 1
a UV-curable silicone pressure-sensitive adhesive composition comprising: (A) 100 parts by weight of an organopolysiloxane containing per molecule two groups having the general formula (1)... (C) 1 to 1,000 parts by weight of an organopolysiloxane resin comprising (a) units having the general formula (2)... (D) 0.01 to 20 parts by weight of a photopolymerization initiator
Data Source
AI summary
(A) an organopolysiloxane having, per molecule, two groups each represented by formula (1)(R1 represents a C1-20 monovalent hydrocarbon group, R2 represents an oxygen atom or the like, R3 represents an acryloyloxyalkyl group or the like, and p and a respectively represent numbers satisfying 0-10 and 1-3);(B) a monofunctional (meth)acrylate compound not including a siloxane structure;(C) an organopolysiloxane resin which comprises a unit (a) represented by formula (2)(R1, R2, R3, a, and p are identical to those described above), a R43SiO1/2 unit (b) (in the formula, R4 represents a monovalent hydrocarbon group having 1-10 carbon atoms), and a SiO4/2 unit (c), and in which the mole ratio of the total of units (a) and (b) to unit (c) is in a range of 0.4 to 1.2:1; and(D) a photoinitiator.