SnCuIn Solder Metallurgy for Electro-migration Control
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Solution Overview
Problem
The miniaturization of electronics leads to increased challenges with electro-migration in interconnections, causing premature failure due to excessive current stress, particularly in first-level interconnects between the die and package, where conventional solder formulations like SnCu and SnAg are susceptible to rapid nickel diffusion and cavitation.
Innovation Solution
The introduction of indium into tin and copper solder compositions (SnCuIn) to control electro-migration by reducing grain alignment with current flow, enhancing polycrystallization, and thereby reducing material movement and void formation, which addresses the issue of premature failure in interconnects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional solder formulations (SnCu, SnAg) are used in miniaturized electronics, then manufacturing simplicity is maintained, but electro-migration resistance deteriorates due to rapid nickel diffusion and cavitation
Solution Approach 1:
The patent modifies the chemical composition parameters of the solder by adding indium (0.1-2.0 wt%) to conventional SnCu or SnAg formulations. This parameter change fundamentally alters the metallurgical properties, specifically reducing grain alignment with current flow and slowing Sn self-diffusion, thereby improving electro-migration resistance without significantly complicating the manufacturing process
Solution Approach 2:
The invention creates a composite solder material by combining multiple elements (Sn, Cu, Ag, and In) in specific proportions. This composite approach leverages the beneficial properties of each element: Sn provides base solderability, Cu enhances strength, Ag improves reliability, and In specifically addresses electro-migration by disrupting grain structure alignment with current flow
2Volume of moving object
If interconnection pitch is reduced for miniaturization, then device size is reduced, but current density increases leading to enhanced electro-migration damage
Solution Approach 1:
By changing the chemical composition parameter (adding indium), the patent alters the physical properties of the solder, specifically creating a polycrystalline structure with random grain orientation. This parameter change reduces the effectiveness of electro-migration damage mechanisms that rely on grain boundary diffusion, thereby maintaining interconnect reliability despite reduced pitch and higher current densities
Solution Approach 2:
The patent converts the harmful effect of high current density into a beneficial outcome by using indium to create a solder structure where the increased electron flow actually promotes beneficial diffusion pathways while the random grain orientation prevents catastrophic failure modes, effectively turning the miniaturization challenge into an opportunity for improved reliability
3Reliability
If indium is added to solder composition, then electro-migration control is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies partial action by adding a relatively small amount of indium (0.1-2.0 wt%) rather than requiring precise control of large quantities of multiple elements. This partial addition is sufficient to achieve the desired metallurgical effects (grain structure modification, diffusion rate reduction) while keeping manufacturing precision requirements manageable through established soldering processes
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 use of SnCuIn solder significantly reduces electro-migration-induced damage by slowing down Sn self-diffusion and reducing cavitation, enhancing the strength and reliability of interconnections, thus preventing premature device failure.
Implementation Method 1
enhancing polycrystallization, and thereby reducing material movement and void formation
Implementation Method 2
slowing down Sn self-diffusion and reducing cavitation
Implementation Method 3
Electro-migration (EM) is the transport of material caused by the gradual movement of the ions in a conductor that results from momentum transfer between conducting electrons and diffusing metal atoms
Implementation Method 4
reducing cavitation, enhancing the strength and reliability of interconnections
Data Source
AI summary
Embodiments are generally directed to indium solder metallurgy to control electro-migration. An embodiment of an electronic device includes a die; and a package substrate, wherein the die is bonded to the package substrate by an interconnection. The interconnection includes multiple interconnects, and wherein the interconnection includes a solder. The solder for the interconnection includes a combination of tin (Sn), copper (Cu), and indium (In).