Nonlinear Contact Fingers and Angled Plating Traces for Semiconductor Packages
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Solution Overview
Problem
Semiconductor die and lead cracking during the molding process in flash memory storage cards due to mechanical stress, and plating trace detachment from the substrate under pressure contact with host device pins, leading to package failure.
Innovation Solution
The use of contact fingers with nonlinear edges, such as rounded or irregular shapes, and angled plating traces to reduce mechanical stress and prevent detachment, with tapers at the junctions of leads and contact fingers to distribute forces and keep plating traces beneath the lid, avoiding contact with host device pins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If contact fingers with straight edges are used, then manufacturing is simple, but mechanical stress concentrates at the edges causing die and lead cracking during molding
Solution Approach 1:
The patent applies curvature by rounding the edges of contact fingers instead of using straight edges. This curvature distributes mechanical stress during the molding process, preventing concentration at sharp corners that would cause die and lead cracking. The rounded edges maintain manufacturing feasibility while significantly improving reliability during package molding.
2Reliability
If plating traces are positioned to extend beyond the lid, then electrical connection is ensured, but frictional contact with host device pins causes plating trace detachment
Solution Approach 1:
The patent extracts the plating traces from the area that would contact host device pins by positioning them to terminate beneath the lid. This removes the harmful frictional contact while maintaining electrical connectivity through the lid structure, preventing plating trace detachment and improving long-term reliability.
3Reliability
If tapers are added at junctions of leads and contact fingers, then mechanical stress is distributed, but manufacturing complexity increases
Solution Approach 1:
The patent changes the geometric parameters of the contact finger junctions by adding tapers. This gradual transition in geometry distributes mechanical stress more evenly across the junction of leads and contact fingers, reducing peak stress concentrations. The taper design balances improved stress distribution with reasonable manufacturing complexity.
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 effectively reduces die cracking and lead breakage during molding and prevents plating trace detachment, enhancing the reliability and longevity of semiconductor packages by distributing mechanical stress and protecting plating traces from frictional contact.
Implementation Method 1
contact fingers with nonlinear edges, such as rounded or irregular shapes, and angled plating traces to reduce mechanical stress
Implementation Method 2
with tapers at the junctions of leads and contact fingers to distribute forces
Implementation Method 3
keeping plating traces beneath the lid, avoiding contact with host device pins
Data Source
AI summary
A strengthened semiconductor die substrate and package are disclosed. The substrate may include contact fingers formed with nonlinear edges. Providing a nonlinear contour to the contact finger edges reduces the mechanical stress exerted on the semiconductor die which would otherwise occur with straight edges to the contact fingers. The substrate may additionally or alternatively include plating traces extending at an angle from the contact fingers. Extending at an angle, at least the ends of the plating traces at the edge of the substrate are covered beneath a lid in which the semiconductor package is encased. Thus, when in use with a host device, contact between the ends of the plating traces beneath the lid and contact pins of the host device is avoided.