Hybrid Semiconductor Package Bonding Wire Material Selection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-temperature RF Joule heating poses challenges for bonding wires in semiconductor packages, with gold being expensive and copper prone to oxidation, while aluminum has reduced conductivity and thermal performance.
Innovation Solution
The use of gold bonding wires or ribbons for high-temperature applications and copper or aluminum for lower temperature components within the same semiconductor package, with gold accommodating greater RF Joule heating and copper or aluminum providing reliable, cost-effective performance at lower temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If gold bonding wires are used for high-temperature RF applications, then temperature resistance is improved, but manufacturing cost increases
Solution Approach 1:
The patent applies different materials to different bonding wires based on their specific thermal environments. Gold bonding wires are used specifically for tuning wires that experience high RF Joule heating (above 150°C), while copper or aluminum bonding wires are used for input/output connection wires that operate at lower temperatures. This localized material selection optimizes both temperature resistance and manufacturing cost by applying expensive gold only where thermally necessary.
2Ease of manufacture
If copper bonding wires are used for cost reduction, then manufacturing cost decreases, but oxidation resistance worsens at high temperatures
Solution Approach 1:
The patent assigns copper or aluminum bonding wires to positions where they will not be subjected to high temperatures that would cause oxidation. Specifically, copper/aluminum wires are used for input and output connection wires that carry lower currents and operate below critical oxidation temperatures, while gold wires are reserved for tuning wires that experience high RF Joule heating. This spatial differentiation of material properties ensures both cost-effectiveness and reliability.
3Reliability
If aluminum bonding wires are used to avoid oxidation, then oxidation resistance is improved, but electrical conductivity and thermal conductivity decrease
Solution Approach 1:
The patent utilizes aluminum bonding wires specifically for applications where oxidation resistance is needed but high electrical and thermal conductivity is not critical. Aluminum wires are employed for certain input/output connections where the current load and thermal generation are lower. For positions requiring high conductivity (tuning wires with high RF currents), gold or copper wires are selected instead, creating an optimized material distribution across the package.
4Temperature
If the number of bonding wires is increased to reduce heating, then temperature resistance is improved, but device complexity increases
Solution Approach 1:
The patent changes the material parameter (from uniform copper/aluminum to selective gold usage) rather than changing the quantity parameter (number of wires). By using gold bonding wires for tuning wires, the patent achieves better temperature resistance without increasing the number of bonding wires. This material substitution approach reduces heating effects in critical paths while maintaining device complexity at acceptable levels.
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
This configuration allows for reliable operation of semiconductor packages at high temperatures without oxidation, ensuring extended device lifetime and reduced costs by utilizing gold for high-temperature components and less expensive materials for lower temperature ones.
Implementation Method 1
the temperature of the tuning wires often exceeds about 150° C. to 160° C., and even 200° C. in certain applications, due to RF Joule heating, i.e., ohmic heating and resistive heating whereby the tuning wires release heat as a result of electric current passing through the wires at RF frequencies
Implementation Method 2
Aluminum bonding wires are less sensitive to the temperature issues described above as compared to copper bonding wires, and have a self-passivating oxide layer that limits further oxidation
Data Source
AI summary
A semiconductor package includes a substrate, an RF semiconductor die attached to a first side of the substrate, a capacitor attached to the first side of the substrate, and a first terminal on the first side of the substrate. The semiconductor package further includes copper or aluminum bonding wires or ribbons connecting the first terminal to an output of the RF semiconductor die, and gold bonding wires or ribbons connecting the capacitor to the output of the RF semiconductor die. The gold bonding wires or ribbons are designed to accommodate greater RF Joule heating during operation of the RF semiconductor die than the copper or aluminum bonding wires or ribbons. Corresponding methods of manufacturing are also described.