UV-Curable Pressure-Sensitive Adhesive Sheet for Semiconductor Wafer Processing
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Solution Overview
Problem
Pressure-sensitive adhesive sheets used in semiconductor wafer processing face challenges in achieving high anchoring strength between the base material and the adhesive layer while minimizing adhesive residue during peeling, especially with aqueous-based adhesives which may not provide sufficient anchoring and can leave residue.
Innovation Solution
A pressure-sensitive adhesive sheet comprising a water-dispersed pressure-sensitive adhesive composition including a water-dispersed acrylic polymer, an active energy ray-curable resin, and a photopolymerization initiator, with a cross-linking agent, applied on a base material such as a polyethylene terephthalate-based resin film, which exhibits a change ratio of −50% or more in anchoring strength after UV irradiation, ensuring strong adhesion and easy peelability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a high pressure-sensitive adhesive strength is used to hold the semiconductor wafer during processing, then the wafer can be appropriately held during backgrinding and dicing steps, but the adhesive may break the wafer during peeling
Solution Approach 1:
The patent applies a preliminary UV irradiation treatment to the adhesive layer before peeling is required. This preliminary action modifies the adhesive properties in advance, reducing the adhesive strength specifically for the peeling operation while maintaining the high adhesive strength needed during the processing steps (backgrinding and dicing). The UV irradiation is applied at an optimal timing before the peeling operation to ensure the adhesive layer has the appropriate properties for easy removal without damaging the wafer.
Solution Approach 2:
The patent creates a dynamic adhesive system where the adhesive strength can be changed based on operational requirements. The adhesive layer transitions from a high-strength state during processing to a low-strength state for peeling through UV irradiation. This dynamic adjustment allows the same adhesive layer to provide strong holding during processing and easy removal during peeling, eliminating the need for different adhesive layers for different operations.
2Object-generated harmful factors
If an aqueous pressure-sensitive adhesive is used to reduce environmental load, then environmental friendliness is improved, but the anchoring property to base material is insufficient and adhesive residue occurs on the adherend
Solution Approach 1:
The patent uses a composite adhesive system combining water-dispersed acrylic polymer with UV-curable resin components. This composite approach allows the adhesive to maintain water-dispersed (environmentally friendly) characteristics while incorporating UV-curable elements that provide strong anchoring properties. The combination enables both environmental compatibility and sufficient adhesive strength to the base material, eliminating the trade-off between eco-friendliness and anchoring performance.
Solution Approach 2:
The patent modifies the chemical and physical parameters of the aqueous adhesive through UV irradiation. The irradiation changes the polymerization state and cross-linking density of the adhesive layer, transforming its properties to achieve strong anchoring to the base material. This parameter change allows the aqueous adhesive to overcome its inherent weak anchoring issue while maintaining the environmental benefits of being water-based.
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 solution provides excellent anchoring strength and prevents adhesive residue on the semiconductor wafer during peeling, ensuring effective holding and easy removal in semiconductor wafer processing.
Implementation Method 1
a water-dispersed pressure-sensitive adhesive composition including a water-dispersed acrylic polymer, an active energy ray-curable resin, and a photopolymerization initiator
Data Source
AI summary
Provided is a pressure-sensitive adhesive sheet that is excellent in anchoring strength between a base material and a pressure-sensitive adhesive layer, and that is suppressed from causing an adhesive residue at the time of its peeling. The pressure-sensitive adhesive sheet includes: a base material; and a pressure-sensitive adhesive layer formed of a water-dispersed pressure-sensitive adhesive composition including a water-dispersed acrylic polymer, an active energy ray-curable resin, and a photopolymerization initiator. The pressure-sensitive adhesive sheet has a change ratio of −50% or more, which is calculated from the following equation: Change ratio (%)={(anchoring strength after UV irradiation-anchoring strength before UV irradiation)/anchoring strength before UV irradiation}×100.