Semiconductor Lead Layout for Thermal Stress Balance
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Solution Overview
Problem
Existing semiconductor devices face issues with excessive thermal stress on conductive bonding members due to uneven distribution of lead lengths and array pitches, particularly at the ends and corners, leading to potential failure and reduced reliability.
Innovation Solution
The semiconductor device employs a lead configuration where the leads at opposite ends and corners have longer lengths and specific array pitches to evenly distribute thermal stress, ensuring balanced stress distribution on conductive bonding members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If leads have uniform lengths and array pitches, then manufacturing is simple, but thermal stress concentrates at ends and corners causing reliability issues
Solution Approach 1:
The patent applies local quality by varying lead lengths based on position: leads at opposite ends and corners have longer lengths than intermediate leads. This non-uniform configuration specifically addresses high-stress regions (ends and corners) with longer leads to distribute thermal stress, while intermediate leads remain shorter. The array pitch also varies locally with wider spacing at ends and narrower spacing in intermediate regions, optimizing stress distribution where needed without affecting other areas.
Solution Approach 2:
The patent employs asymmetry by intentionally creating non-uniform lead lengths and array pitches throughout the structure. Rather than symmetric uniform distribution, the configuration asymmetrically places longer leads at critical stress points (opposite ends and corners) and shorter leads in intermediate positions. This asymmetric design breaks the symmetry of uniform lead arrangements to prevent stress concentration at specific locations.
2Reliability
If lead lengths are increased at ends and corners, then thermal stress is distributed evenly, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies segmentation by dividing the lead array into distinct groups with different length characteristics: end leads, corner leads, and intermediate leads. Each segment has specifically controlled length parameters - end and corner leads are longer while intermediate leads are shorter. This segmentation allows independent optimization of each group's dimensions to achieve overall stress balance without requiring ultra-precise control of every individual lead.
Solution Approach 2:
The patent utilizes parameter changes by systematically varying lead length as a key parameter based on position. The length parameter is changed from a uniform value to multiple discrete values (longer for end/corner leads, shorter for intermediate leads). This parameter variation directly controls the mechanical properties and stress distribution characteristics of different lead regions, achieving reliability improvement through controlled parameter diversity rather than uniformity.
Data Source
AI summary
A semiconductor device includes a semiconductor element, a plurality of leads, and a sealing resin covering the semiconductor element and the plurality of leads. The sealing resin includes a resin reverse surface and first to third resin side surfaces. The plurality of leads include a plurality of first leads aligned in the first direction. Each of the first leads includes a first mounting surface exposed from the resin reverse surface. The first mounting surface reaches the first resin side surface, and is spaced apart from the second resin side surface and the third resin side surface. The first mounting surface has a first length in the second direction. The first length of each of the first leads located at opposite ends in the first direction is longer than the first length of any of a rest of the first leads.