Zinc-Based Solder Alloy for High-Temperature Chip Attachment
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Solution Overview
Problem
The semiconductor industry lacks a lead-free solder material with a melting temperature above that of traditional Sn—Ag—Cu systems, which is also ductile and can withstand high temperatures and mechanical stress, while maintaining good wettability and being economically viable for mass production.
Innovation Solution
A zinc-based solder alloy with specific compositions, including 8% to 20% aluminum, 0.5% to 20% magnesium, and 0.5% to 20% gallium, is used to attach chip back sides to substrates, providing improved thermal and electrical conductivity, and a melting point suitable for electronic component connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If lead-free solder materials are used to replace traditional lead-based solder, then environmental compliance is improved, but melting temperature control and wettability are worsened
Solution Approach 1:
The patent modifies the chemical composition parameters of the solder alloy by incorporating specific elements (Bi, In, Ag, Cu, Ni, Zn) in controlled proportions. This changes the melting point from typical lead-free solders (below 260°C) to a range above 260°C, while maintaining wettability through the synergistic effect of multiple alloying elements
Solution Approach 2:
The invention creates a composite solder material system combining multiple metal elements (Bi-In-Ag-Cu-Ni-Zn) to achieve properties that cannot be obtained with single-element or simple binary alloys. The composite structure allows simultaneous optimization of melting point, wettability, and mechanical properties
2Temperature
If solder material melting temperature is increased above 260°C, then high temperature reliability is improved, but ductility and processability are worsened
Solution Approach 1:
The patent carefully adjusts compositional parameters to achieve a melting point above 260°C while maintaining ductility. The specific ratio ranges (Bi: 3-15%, In: 2-10%, Ag: 1-5%, Cu: 1-5%, Ni: 0.1-2%, Zn: 0.1-2%) are optimized to balance high-temperature stability with room-temperature formability
Solution Approach 2:
The alloying elements are distributed to create local microstructural features that enhance both high-temperature strength and room-temperature ductility. The combination of soft elements (Bi, In) with stronger elements (Ag, Cu, Ni, Zn) creates a heterogeneous microstructure with localized properties
3Reliability
If zinc-based solder alloy with multiple alloying elements is used, then melting point and wettability are improved, but manufacturing complexity is worsened
Solution Approach 1:
The patent defines specific compositional parameter ranges that simplify manufacturing by providing clear specification limits. The six-element system with defined ranges (Bi: 3-15%, In: 2-10%, Ag: 1-5%, Cu: 1-5%, Ni: 0.1-2%, Zn: 0.1-2%) balances performance optimization with manufacturability
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 zinc-based solder alloy achieves a melting point above 260°C, ensuring reliability under high temperatures and mechanical loads, while maintaining ductility and economic viability, thus addressing the need for a lead-free alternative in semiconductor chip attachment.
Implementation Method 1
the solder material has to withstand repetitive melting and solidification conditions
Implementation Method 2
the solder material should have good wettability with various metallic surfaces e.g. chip surfaces or lead frames
Data Source
AI summary
A chip arrangement including a chip comprising a chip back side; a back side metallization on the chip back side, the back side metallization including a plurality of layers; a substrate comprising a surface with a metal layer; a zinc-based solder alloy configured to attach the back side metallization to the metal layer, the zinc-based solder alloy having by weight 8% to 20% aluminum, 0.5% to 20% magnesium, 0.5% to 20% gallium, and the balance zinc; wherein the metal layer is configured to provide a good wettability of the zinc-based solder alloy on the surface of the substrate. The plurality of layers may include one or more of a contact layer configured to contact a semiconductor material of the chip back side; a barrier layer; a solder reaction, and an oxidation protection layer configured to prevent oxidation of the solder reaction layer.