Layered Semiconductor Terminal Structure Against Oxidation and Warping
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Solution Overview
Problem
Leadless package-type semiconductor devices face adhesion failure due to copper oxidation and warping issues, leading to reduced yield and malfunctioning, particularly in in-vehicle applications.
Innovation Solution
A terminal structure with multiple conductive layers and a conductive bonding layer, where the second conductive layer protrudes from the first, ensuring robust adhesion with a conductive bonding material and preventing oxidation, while a semiconductor device design includes this terminal and a resin covering to enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper is used as the lead frame material for external connection, then electrical conductivity is improved, but oxidation occurs resulting in adhesion failure with conductive bonding material
Solution Approach 1:
The patent applies composite material structure by combining copper layer with protective layers (such as nickel or other oxidation-resistant materials) to form a multi-layer lead frame. The copper provides excellent electrical conductivity while the protective outer layer prevents oxidation, thereby resolving the contradiction between maintaining high conductivity and preventing harmful oxidation that causes adhesion failure.
2Reliability
If copper thickness is increased for in-vehicle applications, then electrical performance is improved, but the support member warps resulting in adhesion failure with sealing resin
Solution Approach 1:
The patent divides the lead frame into multiple segments or layers with different thicknesses and materials. By segmenting the structure, the overall copper equivalent thickness can be increased for electrical performance while individual layers maintain appropriate thickness to prevent warping. The multi-layer construction allows each layer to contribute differently - some for conductivity, others for structural stability.
Solution Approach 2:
The patent uses composite material construction with multiple layers of different materials and thicknesses. This allows the lead frame to achieve high electrical performance through sufficient copper content while the distributed structure across multiple layers prevents concentration of stress that would cause warping and adhesion failure with sealing resin.
3Reliability
If copper is made too thick to ensure adequate electrical connection, then electrical conductivity is improved, but adhesion failure occurs due to warping of the support member
Solution Approach 1:
The patent segments the thick copper structure into multiple thinner layers, each contributing to the overall electrical conductivity while individually maintaining structural stability. This segmentation prevents the warping that would occur with a single thick copper layer, as each thinner layer can be better controlled and bonded to adjacent layers and support structures.
Solution Approach 2:
The patent transitions from a single-dimensional thick copper layer to a multi-dimensional layered structure. By distributing the copper thickness across multiple layers in the vertical dimension, the structure achieves the required electrical conductivity through cumulative thickness while each individual layer remains thin enough to prevent warping and maintain adhesion.
Data Source
AI summary
A terminal includes a first conductive layer; a wiring layer on the first conductive layer; a second conductive layer on the wiring layer; and a conductive bonding layer that is in contact with a bottom surface and a side surface of the first conductive layer, a side surface of the wiring layer, a portion of a side surface of the second conductive layer, and a portion of a bottom surface of the second conductive layer, wherein an end portion of the second conductive layer protrudes from an end portion of the first conductive layer and an end portion of the wiring layer, and wherein the conductive bonding layer is in contact with a bottom surface of the end portion of the second conductive layer.