Silicone Resin Composition for Underfill Balancing Curing Time and Pot Life
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Solution Overview
Problem
Conventional silicone compositions used as underfill materials in electronic components have unsatisfactory curing times and pot life at room temperature, affecting their performance and productivity in assembly operations.
Innovation Solution
A resin composition comprising an organopolysiloxane with alkenyl and hydrosilyl groups, a hydrosilylation catalyst, a silane coupling agent, and an unsaturated dicarboxylic acid ester, which is curable within 1 minute to 60 minutes at temperatures between 10°C to 150°C, offering a balance between short curing time and long pot life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional silicone compositions are used as underfill materials, then durability and heat resistance are improved, but curing time is excessively long and pot life at room temperature is unsatisfactory
Solution Approach 1:
The patent changes the chemical composition parameters of the silicone resin by incorporating specific ratios of vinyl-functional polysiloxane (0.1-10 wt%) and hydrosilyl-functional polysiloxane (0.1-10 wt%) along with a platinum catalyst (0.01-10 ppm). This parameter optimization enables the resin to cure within 1-60 minutes while maintaining durability and heat resistance, resolving the contradiction between long curing time and reliability.
2Strength
If epoxy resin is used as underfill material, then bonding and heat cycle resistance are improved, but the resin and curing agent separate and productivity is adversely affected due to long curing time
Solution Approach 1:
The patent replaces the conventional epoxy resin chemical system with a silicone-based chemical system that uses platinum-catalyzed hydrosilylation curing. This substitution eliminates the separation problem between resin and curing agent inherent in epoxy systems while achieving rapid curing (1-60 minutes) that improves productivity, while maintaining bonding strength through the silicone resin's inherent adhesion properties.
3Reliability
If anhydride curing agent is used in epoxy resin, then heat cycle resistance is improved, but bonding and durability are not achieved to satisfactory level
Solution Approach 1:
The patent creates a composite silicone resin system combining vinyl-functional polysiloxane and hydrosilyl-functional polysiloxane with platinum catalyst and controlled water content. This composite material approach achieves both excellent heat cycle resistance and satisfactory bonding strength simultaneously, resolving the contradiction where anhydride curing agents improved heat resistance but compromised bonding performance in epoxy systems.
4Quantity of substance
If capillary flow method is used for underfill material, then filling is achieved, but excessive material flows out from outer periphery requiring strict processing management
Solution Approach 1:
The patent optimizes the viscosity parameter of the silicone resin composition and controls water content (0.01-5 wt%) to regulate the resin's flow characteristics. This parameter control enables the underfill material to fill gaps effectively through capillary action while minimizing excessive flow out from the outer periphery, reducing the need for strict processing management and testing.
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 resin composition exhibits excellent curing characteristics, bonding, and permeability into micrometer-scale gaps, enhancing the reliability and productivity of electronic components while maintaining a suitable viscosity for effective filling.
Implementation Method 1
An addition-reaction silicone resin that employs an addition reaction between an alkenyl group and silicon atom-bonded hydrogen atom (hereafter referred to as a 'hydrosilyl group') exhibits excellent curing characteristics
Implementation Method 2
The filling method for the underfill material includes two methods including a capillary flow method that uses capillary action to fill from the chip peripheral edge
Data Source
Figure 1
AI summary
Disclosed is a resin composition having an excellent balance between shortness of curing time and longness of pot life. The resin composition contains (A) an organopolysiloxane having an alkenyl group, (B) an organopolysiloxane having a silicon atom-bonded hydrogen atom, (C) a hydrosilylation catalyst, (D) a silane coupling agent and (E) an unsaturated dicarboxylic acid ester. The component (B) contains (B-1) an organopolysiloxane having a molecular weight of not less than 5,000 but not more than 50,000 and (B-2) an organopolysiloxane having a molecular weight of not less than 100 but not more than 5,000, and the ratio of (B-2) to (B-1) is preferably not less than 0.01% by mass but not more than 20% by mass.