Adhesive Sheet With Through Holes For Void Suppression
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Solution Overview
Problem
Existing adhesive sheets face challenges in preventing void formation between the adhesive layer and the pressure-sensitive adhesive film, particularly with large-diameter wafers and flip-chip mounting, where the limited number of through holes restricts effective discharge of air or voids, leading to defective attachment and reduced yield.
Innovation Solution
An adhesive sheet design with a long release film, an adhesive layer in a label form, and a pressure-sensitive adhesive film featuring through holes that penetrate the adhesive film, where the maximum width of the through holes and their number per label part are optimized to satisfy a specific ratio relative to the adhesive layer's circumference, ensuring effective void discharge and minimizing air entry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of through holes is increased to discharge air effectively, then void formation is suppressed, but air may enter from outside via through holes causing defective attachment
Solution Approach 1:
The patent applies local quality by making different regions of the pressure-sensitive adhesive film have different properties: the first region (over adhesive layer) contains through holes for air discharge, while the second region (peripheral area) remains intact to prevent air entry. This spatial differentiation of film properties resolves the contradiction between needing holes for void suppression and needing coverage for protection.
Solution Approach 2:
The pressure-sensitive adhesive film is segmented into two distinct regions: a first region with through holes positioned over the adhesive layer for air discharge, and a second region without through holes at the periphery for air barrier function. This segmentation allows each region to perform its specific function, resolving the contradiction between air discharge and air prevention.
2Ease of operation
If a precut adhesive sheet is used to improve workability, then attachability to wafer and ring frame is enhanced, but air remains in narrow gaps between release film and pressure-sensitive adhesive film
Solution Approach 1:
The patent applies preliminary action by pre-forming through holes in the pressure-sensitive adhesive film before the lamination process. This ensures air discharge pathways are already in place when the release film and pressure-sensitive adhesive film are laminated together, preventing air entrapment in narrow gaps while maintaining the precut sheet's workability benefits.
Solution Approach 2:
The pressure-sensitive adhesive film is designed with a porous structure (through holes) in the first region, creating intentional void spaces that allow air to escape during lamination and application processes. This porous design resolves the air entrapment issue while preserving the precut sheet's ease of operation.
3Strength
If the adhesive layer has large thickness (65 μm or more) to function as die bonding film, then bonding capability is improved, but air remains in gaps between release film and pressure-sensitive adhesive film
Solution Approach 1:
The patent applies local quality by positioning through holes specifically in the first region of the pressure-sensitive adhesive film that overlaps the adhesive layer, while maintaining the adhesive layer's full thickness for bonding capability. The through holes are localized to where they are needed for air discharge without compromising the adhesive layer's bonding function.
Solution Approach 2:
The pressure-sensitive adhesive film incorporates a porous structure with through holes in the first region, creating air escape pathways that work in conjunction with the thick adhesive layer. This allows the adhesive layer to maintain its required thickness for die bonding while the porous film structure prevents air entrapment in the overall assembly.
Data Source
AI summary
The adhesive sheet wound into a roll includes: a long release film; an adhesive layer provided in a label form on the release film; and a pressure-sensitive adhesive film having a label part covering the adhesive layer and provided so as to be in contact with the release film around the adhesive layer and a peripheral part surrounding an outside of the label part, wherein a through hole penetrating the pressure-sensitive adhesive film is provided outside a portion corresponding to a part of the adhesive layer intended to be attached to an adherend and inside the label part, and wherein outer circumference of the adhesive layer× 1/43≦maximum width of the through hole×number of the through holes per label part of the pressure-sensitive adhesive film≦outer circumference of the adhesive layer is satisfied.