Zero Fillet Resin Flip Chip Package Design
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Solution Overview
Problem
Flip chip packaging is hindered by resin fillet formation due to thermal expansion mismatch between the chip and substrate, leading to increased package size and potential electrical connection issues.
Innovation Solution
A controlled volume of resin is deposited between the substrate and flip chip die to form a zero fillet resin, preventing resin fillet formation and allowing wire bonds to be made closer to the die, thereby minimizing package size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resin is deposited to reduce thermal expansion mismatch stresses, then stress relief is improved, but resin fillet formation occurs causing package size increase
Solution Approach 1:
The patent modifies the resin deposition parameters by precisely controlling the volume and placement of resin material. By depositing a controlled volume of resin (0.5-2.0 microliters) at specific locations, the patent achieves stress relief without the resin bleeding out to form fillets that increase package size. This parameter control resolves the contradiction between stress relief and package size.
Solution Approach 2:
The patent applies preliminary action by depositing the resin before wire bonding operations. The resin is placed in controlled volumes at predetermined locations on the substrate, allowing stress relief to be established before subsequent bonding steps. This preliminary resin placement prevents fillet formation during later processing while maintaining the stress-mitigation benefits.
2Reliability
If resin volume is increased to ensure adequate stress relief, then stress relief is improved, but lateral displacement of wire bond connection increases
Solution Approach 1:
The patent applies local quality by depositing resin in specific localized areas rather than uniformly across the entire substrate. Controlled volumes of resin are placed at predetermined locations where stress relief is most needed, while leaving other areas free of excess resin. This localized approach ensures adequate stress relief without creating fillets that would interfere with wire bond connections in critical areas.
Solution Approach 2:
The resin is deposited in advance at precisely controlled locations and volumes before wire bonding. This preliminary, localized resin placement creates stress relief zones without forming lateral fillets that would displace wire bonds. The predetermined placement patterns ensure that resin is present where needed for stress relief but absent from areas requiring clean wire bond access.
3Reliability
If resin is allowed to bleed out to form fillet, then stress relief is improved, but package footprint increases
Solution Approach 1:
The patent fundamentally changes the resin deposition parameters by using controlled, small volumes (0.5-2.0 microliters) deposited at specific locations. This prevents the resin from bleeding out laterally to form fillets. The parameter control ensures that resin remains contained at deposition sites, providing stress relief through the controlled volume rather than through lateral fillet formation, thereby maintaining a compact package footprint.
Solution Approach 2:
The patent performs preliminary resin deposition with precise volume and location control before any bonding or encapsulation steps. By establishing the resin placement parameters in advance and depositing controlled volumes at predetermined locations, the resin is prevented from laterally displacing to form fillets. This preliminary controlled placement achieves stress relief while maintaining minimal package footprint.
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 solution effectively reduces package size by eliminating resin fillet formation, allowing for more compact integrated circuit packaging and cost savings through reduced material usage.
Implementation Method 1
the resin employed to reduce stresses arising from the excessive coefficient of thermal expansion (CTE) mismatch between the chip and the substrate
Implementation Method 2
adhering the flip chip die to the first surface of the substrate to form the controlled volume of resin into a zero fillet resin
Data Source
AI summary
An integrated circuit packaging system comprised by providing a substrate with a first surface including conductive regions for receiving a flip chip die and a second surface including electrical contacts for external electrical connections. Providing the flip chip die over the substrate. Depositing a controlled volume of resin between the first surface of the substrate and the flip chip die and adhering the flip chip die to the first surface of the substrate to form the controlled volume of resin into a zero fillet resin.