Inkjet Photo-Thermosetting Adhesive for Semiconductor Devices
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional adhesives for semiconductor devices face challenges in achieving high thickness accuracy and preventing voids, especially with complex wiring patterns and height differences, leading to reliability issues and reduced yield due to adhesive spreading and clinging during dicing.
Innovation Solution
A photocurable and thermosetting adhesive for inkjet applications, comprising a photocurable compound with (meth)acryloyl groups, a thermosetting compound with epoxy or thiirane groups, and a photopolymerization initiator, with a specific composition and properties that allow for controlled elastic modulus and viscosity, enabling precise layer formation and minimal void generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a paste-like adhesive is used for joining semiconductor elements, then the adhesive can provide strong bonding strength, but the adhesive spreads and protrudes, making it difficult to control thickness and leading to wire bonding defects
Solution Approach 1:
The patent changes the physical state parameter of the adhesive from paste-like to liquid state with controlled viscosity (10-1000 cP). This parameter change allows the adhesive to be precisely deposited by inkjet method without spreading or protrusion, while maintaining adequate bonding strength through subsequent curing processes.
Solution Approach 2:
The patent replaces the mechanical application method (paste application) with an inkjet deposition system. This substitution enables precise control of adhesive placement, thickness, and volume, eliminating the spreading and protrusion issues inherent in paste-like adhesives while maintaining bonding effectiveness.
2Manufacturing precision
If an adhesive sheet with film-like adhesive layer is used, then the adhesive layer can maintain thickness accuracy, but the adhesive sheet clings to the cutting blade during dicing, deteriorating cutting properties and reducing yield
Solution Approach 1:
The patent extracts the adhesive layer from the adhesive sheet structure, applying the liquid adhesive directly to the substrate using inkjet method. This extraction eliminates the carrier sheet that causes clinging during dicing, while maintaining thickness accuracy through precise inkjet deposition control.
Solution Approach 2:
The patent introduces a liquid adhesive as an intermediary material that can be precisely deposited and then cured. This liquid adhesive replaces the film-like adhesive layer on adhesive sheets, providing the benefits of thickness control without the harmful effect of clinging to cutting blades during dicing.
3Strength
If a adhesive with high elastic modulus after photo-curing is used, then the adhesive provides strong structural support, but the adhesive layer generates voids in areas with height differences in wiring patterns, decreasing reliability
Solution Approach 1:
The patent creates a dynamic curing process where the adhesive transitions from liquid state (low viscosity for filling) to cured state (high strength). The two-stage curing approach allows the adhesive to first fill height differences when compliant, then develop structural strength, eliminating voids while maintaining structural support.
Solution Approach 2:
The patent uses a composite adhesive system combining photopolymerizable compounds and epoxy compounds with different curing mechanisms. This composite formulation provides both the flowability needed to fill height differences and the structural strength required for support, while the dual-curing process ensures complete void elimination.
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 ensures high thickness accuracy and reduces void formation, enhancing the reliability and yield of semiconductor devices by providing a balanced elastic modulus and viscosity, suitable for inkjet application and thermal curing.
Implementation Method 1
containing (a) a photocurable compound having a (meth)acryloyl group, (b) a thermosetting compound having an epoxy group or a thiirane group, (c) a photocurable and thermosetting compound having a (meth)acryloyl group and having an epoxy group or a cyclic thioether group, (d) a photopolymerization initiator
Implementation Method 2
containing (e) a thermal curing agent wherein the elastic modulus at 25°C of a B-staged adhesive is at least 5.0 × 10² Pa and at most 8.0 × 10⁴ Pa when the B-staged adhesive is obtained by irradiating the adhesive with light
Data Source
Figure 1
Figure 2(a)~2(e)
Figure 3~4
AI summary
Provided is a photocurable and thermosetting adhesive for inkjet which can increase the thickness accuracy of an adhesive layer formed by curing an adhesive and can further cause the adhesive layer to hardly generate voids. A photocurable and thermosetting adhesive for inkjet according to the present invention contains a photocurable compound, a thermosetting compound, a photopolymerization initiator, and a thermal curing agent, wherein the elastic modulus at 25°C of a B-staged adhesive is at least 5.0 × 102 Pa and at most 8.0 0 × 104 Pa when the B-staged adhesive is obtained by irradiating the adhesive with light of a cumulative light quantity of 1000 mJ/cm2 so that illumination at a wavelength of 365 nm is 100 mW/cm2.