Lead Frame Terminal Layout for Reliable Semiconductor Packaging
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Solution Overview
Problem
Conventional semiconductor packages face issues of excess cost, decreased reliability, and large package sizes, leading to inadequate performance.
Innovation Solution
The development of semiconductor devices with a lead frame substrate design featuring a first and second external terminal separated by a gap, chamfered cutouts, and grooves to improve adhesion and reduce stress, along with a method of manufacturing that includes encapsulation and plating to enhance reliability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional semiconductor packages are used, then manufacturing cost is reduced, but reliability decreases and package size becomes too large
Solution Approach 1:
The lead frame is divided into multiple segments including a body portion, external terminals, and internal contacts. The external terminals are separated by gaps and feature chamfered cutouts, creating discrete functional zones that improve bond reliability while managing complexity through modular design
Solution Approach 2:
Different regions of the lead frame are given different properties: external terminals have chamfered cutouts for stress reduction, gaps between terminals for adhesion improvement, and specific geometries for heat dissipation. This localized optimization resolves the contradiction by enhancing reliability in critical areas without uniformly increasing complexity
2Productivity
If conventional packaging methods are used, then manufacturing process is simple, but manufacturing yields decrease
Solution Approach 1:
Chamfered cutouts are pre-formed in the external terminals during lead frame fabrication, before assembly and encapsulation. This preliminary structuring of stress concentration zones improves manufacturing yields by preventing defects during subsequent processing, while the cutouts are created using standard forming techniques that don't significantly increase process complexity
3Stability of the object's composition
If conventional lead frame design is used, then device assembly is straightforward, but twisting and stress occur during manufacturing
Solution Approach 1:
Chamfered cutouts are designed into external terminals to preemptively counteract twisting and stress forces that occur during assembly and encapsulation. The chamfered geometry creates stress distribution patterns that resist deformation, maintaining structural stability without complicating the assembly process
Solution Approach 2:
The external terminals feature asymmetric chamfered cutouts rather than symmetric designs. This asymmetry optimizes stress distribution in the direction of expected manufacturing forces, improving structural stability while the overall lead frame maintains sufficient symmetry for ease of assembly
4Temperature
If conventional package design is used, then heat dissipation is insufficient, but increasing heat dissipation capacity increases package size
Solution Approach 1:
Heat dissipation is enhanced by utilizing the vertical dimension through exposed external terminals that conduct heat from the semiconductor device to the package exterior. The chamfered cutouts and gap structures create three-dimensional heat pathways that improve thermal management without increasing the planar footprint of the package
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 bond reliability, reduces twisting and stress during manufacturing, and improves heat dissipation, resulting in improved manufacturing yields and device quality.
Implementation Method 1
An encapsulant covers the substrate and the electronic component
Implementation Method 2
a method of manufacturing that includes encapsulation and plating to enhance reliability and performance
Data Source
AI summary
An electronic device includes a substrate comprising a contact including a contact first lateral side and a contact second lateral side. A contact first external terminal extends outward from the contact first lateral side. A contact second external terminal extends outward from the contact first lateral side and is separated from the contact first external terminal by gap. An electronic component is coupled to the contact. An encapsulant covers the substrate and the electronic component. The encapsulant comprises an encapsulant top side, an encapsulant bottom side opposite to the encapsulant top side, and an encapsulant lateral side. The contact first external terminal, the contact second external terminal, are exposed from the encapsulant. A lower side of contact is exposed from the encapsulant top side. The encapsulant covers a portion of the gap proximate to the contact first lateral side. Other examples and related methods are disclosed herein.