Curable Polymer Underfill Composition for SMT Reflow Reinforcement
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Solution Overview
Problem
Conventional underfill materials for electronic assemblies require separate curing steps, increasing process complexity and cost, and do not effectively address thermomechanical fatigue and mechanical strength issues in solder joints, especially in flip-chip and CSP LED assemblies.
Innovation Solution
A curable polymer composition incorporating polyhedral oligomeric silsesquioxanes and functionalized graphene, which can be processed using standard SMT reflow processes, providing improved mechanical and thermal fatigue resistance, and can be used as a solder flux or conductive adhesive to reinforce solder joints and interconnects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional underfill materials are used to protect solder joints, then reliability against thermomechanical fatigue is improved, but device complexity increases due to separate curing steps
Solution Approach 1:
The patent combines the underfill material application and curing steps with the existing solder reflow process. The underfill composition is applied to the solder joints and cured simultaneously with the solder reflow, eliminating the need for separate underfill curing steps and reducing overall process complexity while maintaining reliability benefits
2Strength
If the amount of filler is increased in underfill composition, then mechanical properties are improved, but viscosity increases making processing difficult
Solution Approach 1:
The patent modifies the chemical composition parameters of the underfill material by incorporating specific reactive diluents and curing agents that enable high filler content (improving mechanical properties) while maintaining lower viscosity through chemical reactions during curing, allowing the material to flow easily during application then strengthen upon curing
3Strength
If separate curing steps are added for underfill materials, then mechanical strength is improved, but productivity decreases
Solution Approach 1:
The patent merges the underfill curing process with the solder reflow process by timing the curing step to occur simultaneously with the solder melting and bonding process. This integration eliminates idle time and sequential waiting, maintaining high mechanical strength development while maximizing production throughput
4Productivity
If standard SMT reflow processes are used, then productivity is improved, but curing of underfill materials cannot be achieved
Solution Approach 1:
The patent formulates the underfill composition with curing agents and reactive components specifically designed to activate and complete curing within the temperature and time parameters of standard SMT reflow processes, eliminating the need for separate curing equipment or process modifications while ensuring complete curing for reliable joints
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 composition simplifies the electronic assembly process by curing during the solder reflow step, enhancing the mechanical and thermal properties of solder joints, reducing the risk of current leakage and package tilt, and improving reliability without additional cleaning steps.
Implementation Method 1
a curable polymer composition... which can be processed using standard SMT reflow processes... curing during the solder reflow step
Implementation Method 2
incorporating polyhedral oligomeric silsesquioxanes and functionalized graphene... enhancing the mechanical and thermal properties of solder joints
Implementation Method 3
The boards then enter a zone where the temperature is high enough to melt the solder particles in the solder paste... The surface tension of the molten solder helps keep the components in place
Data Source
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AI summary
A composition for use in an electronic assembly process, the composition comprising a filler dispersed in an organic medium, wherein: the organic medium comprises a polymer; the filler comprises one or more of graphene, functionalised graphene, graphene oxide, a polyhedral oligomeric silsesquioxane, graphite, a 2D material, aluminium oxide, zinc oxide, aluminium nitride, boron nitride, silver, nano fibres, carbon fibres, diamond, carbon nanotubes, silicon dioxide and metal-coated particles, and the composition comprises from 0.001 to 40 wt.% of the filler based on the total weight of the composition.