Pre-applied Underfill Adhesive for Flip Chip Mounting
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Solution Overview
Problem
Conventional adhesives used in flip chip mounting, particularly those containing epoxy resins, have a short pot life, require long curing times, and can corrode electronic materials, making them unsuitable for efficient semiconductor chip production due to high heat requirements and operational complexities.
Innovation Solution
A pre-applied underfill sealant adhesive composition comprising a radical polymerizable monomer, a polymer with polar groups, a filler, and a thermal radical initiator, which can be B-staged to have a longer pot life and shorter curing time, ensuring efficient thermal compression bonding and reduced corrosion risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If epoxy resin adhesive is used for underfill, then adhesion strength and mechanical strength are improved, but pot life becomes short and curing time increases
Solution Approach 1:
The patent changes the chemical composition parameters of the adhesive from epoxy resin to a combination of polyol polymer and isocyanate compound. This parameter change in material chemistry provides different reactivity characteristics, resulting in extended pot life while maintaining adequate adhesion strength for the underfill application.
2Strength
If epoxy resin adhesive is used for underfill, then adhesion strength is improved, but curing time becomes long
Solution Approach 1:
The patent modifies the chemical composition parameters by replacing epoxy resin with polyol polymer and isocyanate compound systems. These materials exhibit different curing kinetics with lower viscosity and faster reaction rates, reducing the overall curing time while providing sufficient bond strength for semiconductor chip mounting.
3Strength
If epoxy resin adhesive is used for underfill, then mechanical strength is improved, but heat of reaction increases causing temperature control difficulty
Solution Approach 1:
The patent changes the chemical composition from epoxy resin to polyol polymer and isocyanate compound systems. These materials have lower heat of reaction during curing, which simplifies temperature control during the mounting process and reduces thermal stress on the semiconductor chip while still achieving the required mechanical strength.
4Strength
If epoxy resin adhesive is used for underfill, then adhesion performance is improved, but chlorine concentration increases causing corrosion risk
Solution Approach 1:
The patent extracts and eliminates the harmful chlorine element from the adhesive composition by replacing epoxy resin with polyol polymer and isocyanate compound systems. This removal of the corrosive component reduces the risk of corrosion to electronic materials while maintaining the necessary adhesion performance for the underfill application.
5Productivity
If pre-applied adhesive method is used to foreshorten mounting process, then productivity is improved, but adhesive application step complexity increases
Solution Approach 1:
The patent applies the preliminary action principle by pre-coating the substrate with the adhesive composition before chip mounting. This allows the adhesive to be applied in advance under controlled conditions, simplifying the actual mounting process and improving productivity. The B-staging process further simplifies handling by providing a non-tacky, dimensionally stable adhesive layer ready for immediate use.
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 composition provides a longer pot life, shorter curing time, and improved adhesion, enhancing the efficiency and productivity of electronic device production while minimizing corrosion risks and operational complexities.
Implementation Method 1
a thermal radical initiator
Implementation Method 2
a radical polymerizable monomer having one or more functional groups selected from the group consisting of vinyl group, maleimide group, acryloyl group, methacryloyl group and allyl group
Implementation Method 3
allowing the resin composition to flow into the gap between the wiring board and the chip by capillary action
Data Source
AI summary
An adhesive composition for a pre-applied underfill sealant comprising: (a) a radical polymerizable monomer having one or more functional groups selected from the group consisting of vinyl group, maleimide group, acryloyl group, methacryloyl group and allyl group, (b) a polymer having a polar group, (c) a filler, and (d) a thermal radical initiator.