Al Bonding Wire Composition to Suppress High-Temperature Recrystallization
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Solution Overview
Problem
Existing Al bonding wires used in semiconductor devices experience insufficient bonding reliability under high temperature conditions due to recrystallization and decreased strength over time.
Innovation Solution
An Al bonding wire containing 0.02 to 1% by mass of Fe and 0.05 to 0.5% by mass of Mn and/or Cr, with a total content of Fe, Mn, and Cr in solid solution ranging from 0.01 to 1% by mass, is developed to enhance bonding reliability by increasing recrystallization temperature and maintaining wire strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high purity Al is used for the bonding wire, then the wire has good electrical conductivity and ease of bonding, but the wire softens at high temperatures (100-150°C) due to recrystallization, reducing bonding reliability
Solution Approach 1:
The patent changes the chemical composition parameters by adding Fe (0.02-1% by weight) and Mn (0.05-0.5% by weight) to the Al bonding wire. This compositional modification increases the recrystallization temperature and maintains wire strength at high operating temperatures (100-150°C) while preserving electrical conductivity and bonding properties
Solution Approach 2:
The patent creates a composite aluminum alloy material by combining Al with Fe and Mn elements. This composite structure provides both the electrical conductivity of pure Al and the high-temperature strength of alloyed material, preventing softening and maintaining bonding reliability under thermal stress
2Strength
If Fe is added to increase recrystallization temperature and prevent softening, then wire strength is improved, but excessive Fe content may cause brittleness and cracking
Solution Approach 1:
The patent precisely controls the Fe content within 0.02-1% by weight and Mn content within 0.05-0.5% by weight. This parameter optimization ensures sufficient strength improvement and recrystallization temperature increase while avoiding excessive brittleness and cracking that would result from higher alloying levels
3Temperature
If the bonding wire is used in high temperature environments (100-150°C), then the device can operate in power semiconductor applications, but recrystallization occurs just above the wire bonding interface, forming small crystal grains that cause cracking
Solution Approach 1:
The patent modifies the material composition by adding Fe and Mn, which directly increases the recrystallization temperature of the bonding wire. This allows the wire to maintain its crystal structure and mechanical properties at high operating temperatures (100-150°C), preventing the formation of small crystal grains and associated cracking at the bonding interface
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 Al bonding wire maintains sufficient bonding reliability and strength even under high temperature conditions by suppressing recrystallization, ensuring high bond shear force and preventing chip cracks.
Implementation Method 1
a total content of Fe, Mn and Cr in solid solution is 0.01 to 1% by mass
Data Source
AI summary
There is provided an Al bonding wire which can achieve a sufficient bonding reliability of bonded parts of the bonding wire under a high temperature state where a semiconductor device using the Al bonding wire is operated. The Al bonding wire is characterized in that the wire contains 0.02 to 1% by mass of Fe, further contains 0.05 to 0.5% by mass in total of at least one or more of Mn and Cr, and the balance includes Al and inevitable impurities, wherein a total content of Fe, Mn and Cr in solid solution is 0.01 to 1% by mass. The Al bonding wire contains Mn and Cr in addition to Fe, so that Fe, Mn and Cr can be promoted to form a solid solution in quenching treatment after the solution treatment. Accordingly, the Al bonding wire can achieve an effect of solid-solution strengthening of the wire due to the increase in the total content of Fe, Mn and Cr in solid solution and an effect of preventing recrystallization from proceeding during use of the semiconductor device at a high temperature for a long time.