Bonding Metal Structure for Electronic Circuit Module
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Solution Overview
Problem
Existing electronic circuit module components face issues with solder scattering or movement during reflow, leading to potential damage and reduced durability, especially when reheated in manufacturing processes.
Innovation Solution
Incorporating a bonding metal with a Ni—Sn alloy phase that disperses within a Sn alloy phase, featuring holes with diameters of 5 μm or less and a center distance of 10 μm or more, along with a Bi alloy phase for enhanced hardness, to prevent remelting and crack progression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If Pb-free solder is used for bonding the electronic component and mounting the electronic circuit module component, then the solder can be used for both bonding and mounting purposes, but the solder scatters or moves upon reflow heating
Solution Approach 1:
The bonding metal is designed as a composite material containing multiple alloy phases (Sn alloy phase, Ni-Sn alloy phase, and Bi alloy phase) with different melting points and mechanical properties. This composite structure allows the bonding metal to maintain stability during reflow heating while providing reliable bonding performance, resolving the contradiction between solder versatility and position stability.
Solution Approach 2:
The bonding metal exhibits local quality variations through its multi-phase composition, where the Ni-Sn alloy phase provides high-temperature stability and the Bi alloy phase enhances hardness and crack resistance. This local differentiation of material properties within the bonding metal enables it to resist scattering and movement during reflow while maintaining bonding functionality.
2Productivity
If the bonding metal is reheated during manufacturing process, then the electronic circuit module component can be mounted on the substrate, but the bonding metal may remelt or suffer damage
Solution Approach 1:
The bonding metal's composition is specifically designed with alloy phases having melting points significantly higher than the reflow heating temperature. The Ni-Sn alloy phase and Bi alloy phase create a material whose melting parameters are decoupled from the processing temperature, allowing repeated heating cycles without remelting or damage, thus ensuring both productivity and reliability.
3Reliability
If the bonding metal is made harder to prevent crack progression, then the durability against crack is improved, but the bonding metal becomes more brittle and susceptible to damage
Solution Approach 1:
The bonding metal employs a composite material strategy where the Bi alloy phase (harder) disperses within the Sn alloy phase matrix. This composite structure provides crack resistance through the harder Bi phase while the Sn matrix maintains overall toughness and ductility, resolving the contradiction between crack resistance and material strength.
Solution Approach 2:
The bonding metal exhibits local quality variations through its multi-phase composition, where the Bi alloy phase provides localized hardness and crack resistance, while the Sn alloy phase matrix maintains overall ductility and toughness. This local differentiation of material properties enables the bonding metal to resist crack progression while avoiding excessive brittleness.
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 inhibits solder remelting and crack propagation, thereby improving the durability and reliability of electronic circuit module components during reflow processes.
Implementation Method 1
an Ni—Sn alloy phase that disperses and forms between the Sn alloy phases and includes at least Fe
Implementation Method 2
the bonding metal including the Ni—Sn alloy phase that has a melting point higher than that of the Sn alloy phase
Implementation Method 3
a plurality of holes that is formed inside the Ni—Sn alloy phase... even when a crack occurs inside the Ni—Sn alloy phase, progress of the crack is inhibited
Implementation Method 4
the bonding metal may further include a Bi alloy phase... Since the bonding metal further includes the Bi alloy phase harder than the Ni—Sn alloy phase, the durability against, for example, the crack can be further improved
Data Source
AI summary
An electronic circuit module component includes: an electronic component; a circuit board including the electronic component mounted thereon; and a bonding metal disposed between a terminal electrode of the electronic component and a terminal electrode of the circuit board, and including Sn alloy phases, an Ni—Sn alloy phase that disperses and forms between the Sn alloy phases and includes at least Fe, and a plurality of holes that is formed inside the Ni—Sn alloy phase and has a diameter of 5 μm or less. A center distance between the holes adjacent to each other is 10 μm or more.