Indium Solder Interconnects for Electromigration-Resistant IC Packages

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Solution Overview

Problem

Semiconductor packages using glass core technology face challenges with electromigration due to shock and sway, which can cause glass breakage, and existing solder materials like tin copper (SnCu) do not meet the Imax requirement, leading to reliability issues.

Innovation Solution

The use of a microball solder alloy composition including indium, such as SnCuIn, combined with a cost-effective organic solderability preservative (OSP) surface finish, which replaces traditional electroless nickel/electroless palladium/immersion gold (ENEPIG) and reduces oxidation, enhances the reliability of interconnect joints and mitigates electromigration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If glass core technology is used, then high frequency performance and signal isolation are improved, but susceptibility to electromigration and shock-induced breakage increases

Engineering Contradiction:

Improvehigh frequency performanceVSAvoidelectromigration susceptibility

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the material composition parameters of the solder interconnect by incorporating indium (e.g., SnCuIn alloy) to modify the electromigration resistance. This parameter change in the interconnect material directly addresses the electromigration susceptibility issue while maintaining the glass core's high frequency performance benefits

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material strategies by combining multiple metal elements (Sn-Cu-In alloy system) to create an interconnect material with superior electromigration resistance. The composite solder alloy integrates the advantages of different metals to withstand the harsh electromagnetic environment in glass core packages

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If traditional SnCu solder material is used, then manufacturing simplicity is maintained, but Imax requirement and reliability are not met

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidImax requirement compliance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent modifies the compositional parameters of the solder material by adding indium to the traditional SnCu alloy, creating SnCuIn compositions that achieve the required Imax values while maintaining manufacturability through established soldering processes

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If ENEPIG surface finish is used, then traditional process compatibility is maintained, but cost increases and oxidation resistance decreases

Engineering Contradiction:

Improveprocess compatibilityVSAvoidoxidation resistance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent replaces the expensive multi-layer ENEPIG surface finish with a simpler, more cost-effective OSP (organic solderability preservative) coating. This substitution reduces both material cost and manufacturing complexity while providing adequate protection against oxidation for the indium-containing solder interconnects

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Data Source

PatentUS20240332134A1Methods and apparatus to mitigate electromigration in integrated circuit packages

Publication Date: 2024.10.03 INTEL CORP

AI summary

Methods and apparatus to mitigate electromigration are disclosed. A disclosed example integrated circuit (IC) package includes a dielectric substrate, a contact pad at least partially extending though or positioned on the dielectric substrate, the contact pad including copper, and a metal interconnect coupled to the contact pad, the interconnect including indium.