UV-Curable Silicone PSA Composition for Accurate Chip Transfer
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Solution Overview
Problem
Existing UV-curable silicone pressure-sensitive adhesive (PSA) compositions experience significant cure shrinkage and inadequate adhesive force, leading to dimensional errors and difficulty in transferring miniaturized chips or parts.
Innovation Solution
A UV-curable silicone PSA composition comprising organopolysiloxane with specific (meth)acryloyloxy-containing groups, organopolysiloxane resin, finely divided silica, and a photoinitiator, without a siloxane-free (meth)acrylate compound, which cures quickly with minimal shrinkage and strong adhesive force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If heat cure type silicone PSA compositions are used, then adhesive force is achieved, but the cured product shrinks upon cooling resulting in increased dimensional errors
Solution Approach 1:
The patent transitions from thermal curing (heat cure) to photopolymerization curing (UV cure) to eliminate the thermal expansion and contraction cycle. The UV-curable silicone PSA composition uses photopolymerization to crosslink at room temperature, avoiding the heating and cooling process that causes shrinkage and dimensional errors in heat-cured materials.
Solution Approach 2:
The patent changes the curing mechanism parameter from thermal energy activation to light energy activation. By incorporating photoinitiators and (meth)acryloyloxy-containing groups into the silicone PSA composition, the material cures via UV irradiation instead of heat, fundamentally changing the energy parameter to eliminate thermal shrinkage.
2Device complexity
If silicone elastomers with inherent adhesive force are used, then material simplicity is maintained, but very weak adhesive forces prevent transfer of certain chips or parts
Solution Approach 1:
The patent creates a composite material system by combining silicone base polymers with (meth)acryloyloxy-containing groups, photoinitiators, and crosslinking agents. This composite approach integrates the benefits of silicone elastomers with the strong adhesive properties and rapid curing characteristics of photopolymerizable systems, achieving both strong adhesion and material functionality.
Solution Approach 2:
The patent merges two distinct chemical systems: the silicone PSA base material and the photopolymerizable (meth)acrylate system. By combining these materials and their curing mechanisms, the invention achieves rapid UV-curable adhesion while maintaining the desirable properties of silicone elastomers, including flexibility and temperature resistance.
3Productivity
If conventional UV-curable silicone PSA compositions are used, then rapid curing is achieved, but significant cure shrinkage occurs leading to dimensional errors
Solution Approach 1:
The patent optimizes the chemical composition parameters of the UV-curable system by selecting specific (meth)acryloyloxy-containing silicone compounds with appropriate molecular weights and functional group densities. This parameter optimization controls the degree of crosslinking and polymerization shrinkage, maintaining rapid curing while minimizing dimensional changes.
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 achieves satisfactory shape retention, minimal cure shrinkage, and excellent pressure-sensitive adhesion, enabling effective transfer of microscopic chips with improved dimensional accuracy.
Implementation Method 1
UV-curable silicone pressure-sensitive adhesive composition comprising: (A) 100 parts by weight of an organopolysiloxane having the general formula (1)
Implementation Method 2
exhibits a satisfactory pressure-sensitive adhesive force
Data Source
Figure 1~3
AI summary
An ultraviolet curable silicone adhesive composition which contains (A) an organopolysiloxane represented by formula (1) (wherein each R1 represents a polymerizable group or a monovalent hydrocarbon group having 1-20 carbon atoms, provided that at least one of the R1 moieties represents a polymerizable group; R2 represents an oxygen atom or an alkylene group having 1-20 carbon atoms; and m and n represent numbers satisfying m ≥ 0, n ≥ 1 and 1 ≤ (m+n) ≤ 1,000), (B) an organopolysiloxane resin which is composed of (a) an R33SiO1/2 unit (wherein R3 represents a monovalent hydrocarbon group having 1-10 carbon atoms) and (b) an SiO4/2 unit, with the molar ratio of the unit (a) to the unit (b) being 0.6-1.2:1, (C) a fine silica powder and (D) a photopolymerization initiator, and which does not contain a (meth)acrylate compound that does not have a siloxane structure. This ultraviolet curable silicone adhesive composition enables the achievement of a cured product that has good shape retainability and little curing shrinkage, while exhibiting excellent adhesiveness if used as a provisional fixing material.