Multi-layer Interconnect Ribbon for Semiconductor Packages
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Solution Overview
Problem
Current interconnect solutions in semiconductor packages, such as bond wires and metal clips, face limitations in current carrying capacity and thermal dissipation, necessitating improved techniques for efficient electrical connection and heat management.
Innovation Solution
A semiconductor package assembly utilizing an interconnect ribbon with a multilayer configuration of different metals, where the first metal layer is mechanically compatible and the second metal layer provides higher conductivity, allowing for solder-free attachment and efficient thermal dissipation through an exposed upper surface for external heat sinks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If bond wires are used for interconnection, then the package structure is simple and easy to manufacture, but the current carrying capacity is low and package resistance increases
Solution Approach 1:
The interconnect ribbon employs a composite structure with a copper core layer providing high electrical conductivity and a nickel overlay layer providing mechanical strength and solderability. This composite material approach enables the ribbon to simultaneously achieve low electrical resistance for high current carrying capacity while maintaining mechanical robustness for reliable bonding to the semiconductor die and contact pad.
2Reliability
If metal interconnect clips are used, then the current carrying capacity is improved, but large bonding surfaces are required
Solution Approach 1:
The interconnect ribbon is constructed as a thin, flexible strip with a cross-section comprising a copper core and nickel overlay. This thin-film structure achieves low electrical resistance through the high-conductivity copper core while the ribbon's flexibility and adherent nickel layer enable reliable bonding to small contact areas on the semiconductor die and contact pad, eliminating the need for large bonding surfaces required by rigid metal clips.
3Device complexity
If a single-layer metal ribbon is used, then the structure is simple, but the electrical conductivity and thermal dissipation are insufficient
Solution Approach 1:
The interconnect ribbon employs a composite structure with a copper core layer providing high electrical conductivity and a nickel overlay layer providing mechanical strength and solderability. This composite material approach enables the ribbon to simultaneously achieve low electrical resistance for high current carrying capacity while maintaining mechanical robustness for reliable bonding to the semiconductor die and contact pad.
Solution Approach 2:
The ribbon structure assigns different materials to different regions: the copper core provides high electrical conductivity where current flows, while the nickel overlay provides mechanical strength and solderability at the bonding surfaces. This local optimization of material properties throughout the ribbon structure achieves superior overall performance.
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 enhances current carrying capacity and reduces electrical resistance while enabling efficient thermal management by leveraging the properties of the second metal layer, such as copper, for improved conductivity and heat dissipation.
Implementation Method 1
fusing the first metal layer and the front side metallization together comprises an ultrasonic wirebonding process without the application of heat
Implementation Method 2
enabling efficient thermal management by leveraging the properties of the second metal layer, such as copper, for improved conductivity and heat dissipation
Data Source
AI summary
A semiconductor package assembly includes a carrier with a die attach surface and a contact pad separated from the die attach surface, a semiconductor die mounted on the die attach surface, the semiconductor die having a front side metallization that faces away from the die attach surface, an interconnect ribbon attached to the semiconductor die and the contact pad such that the interconnect ribbon electrically connects the front side metallization to the contact pad, and an electrically insulating encapsulant body that encapsulates the semiconductor die and at least part of the interconnect ribbon. The interconnect ribbon includes a layer stack of a first metal layer and a second layer formed on top of the first metal layer. The first metal layer includes a different metal as the second metal layer. The first metal layer faces the front side metallization.