Integrated Circuit Package Shunt Support via Tape
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Solution Overview
Problem
The integration of a rectangular copper alloy slug or shunt in integrated circuit packages requires a cost-effective solution, as using expensive alloys like MANGANIN® is not economically viable, while existing methods with less expensive alloys like CDA194 lack efficient methods for incorporating and securing such shunts without increasing package complexity and risk of delamination.
Innovation Solution
A method involving a leadframe constructed from the less expensive CDA194 alloy, where a copper alloy shunt made from MANGANIN® is supported by tape during encapsulation, allowing for selective plating and easy customization, and ensuring only the shunt's bottom surface remains exposed for soldering, thereby avoiding the use of costly and space-consuming rivets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If expensive copper alloy shunt (MANGANIN®) is used, then electrical connection quality is improved, but material cost increases
Solution Approach 1:
The package is divided into two distinct parts: a leadframe made from less expensive CDA194 alloy and a separate shunt made from expensive MANGANIN® alloy. This segmentation allows the expensive material to be used only where critical for electrical connection, while the less expensive material is used for structural components, thereby reducing overall material cost while maintaining connection quality.
Solution Approach 2:
The expensive MANGANIN® alloy is applied locally only to the shunt portion that requires superior electrical connection properties, rather than using it throughout the entire leadframe structure. This localized application of high-quality material optimizes the balance between connection reliability and material cost.
2Strength
If shunt is secured with rivets, then mechanical strength is improved, but package complexity and delamination risk increase
Solution Approach 1:
The rivet securing mechanism is completely removed from the design. Instead of using rivets to mechanically attach the shunt to the leadframe, the shunt is held in place solely by the encapsulant material that fills the cavity, eliminating the need for additional mechanical fasteners and reducing package complexity.
Solution Approach 2:
The function of mechanical securing is merged with the encapsulant material. The encapsulant serves dual purposes: protecting the internal components and simultaneously holding the shunt in position through adhesive bonding, eliminating the need for separate rivet components.
3Manufacturing precision
If multiple components are used to secure shunt, then positioning accuracy is improved, but manufacturing complexity increases
Solution Approach 1:
The encapsulant material performs the self-service function of both positioning and securing the shunt. During the encapsulation process, the adhesive material automatically holds the shunt in the correct position and secures it permanently, eliminating the need for separate positioning fixtures or multiple securing components that would increase manufacturing complexity.
Data Source
AI summary
An integrated circuit package may be formed using a leadframe having an open space extending therethrough. A shunt is located within the open space such that it is not in contact with any portion of the leadframe. Tape may be applied to the lower surface of the leadframe to support the shunt and hold it in place relative to the leadframe until wirebonding and encapsulation have been completed. Thereafter, the tape may be removed.