Semiconductor Leadframe Terminal with Stepped Surface for Resin Adhesion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor devices with etched metal terminals face issues of terminal detachment from the resin during manufacturing, lacking an anchor structure to prevent this, and are prone to moisture ingress leading to the 'popcorn phenomenon' during reflow processes.
Innovation Solution
The semiconductor device incorporates a leadframe with a terminal having a stepped and uneven surface design, increasing the surface area contact with resin for enhanced adhesion and creating a longer moisture entry pathway to prevent detachment and popcorn phenomenon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a terminal is formed by etching a metal plate without an anchor structure, then the manufacturing process is simple, but the terminal detaches from the resin during manufacturing
Solution Approach 1:
The terminal surface is transformed from a flat planar surface to a curved spherical surface with radius R1. This curvature creates an anchor structure that mechanically interlocks with the resin, preventing terminal detachment while maintaining manufacturing simplicity through a single etching process that forms both the pillar shape and spherical surface
Solution Approach 2:
The invention changes the surface geometry parameter from flat to spherical with a specific radius R1. This parameter change creates the anchor effect that improves terminal adhesion to resin without complicating the manufacturing process, as the spherical surface is formed simultaneously with the terminal pillar during the etching process
2Ease of manufacture
If a terminal has a smooth planar surface, then the manufacturing process is simple, but moisture easily enters the terminal-resin interface causing popcorn phenomenon
Solution Approach 1:
The spherical surface with radius R1 creates a curved interface between the terminal and resin, which eliminates flat surfaces where moisture can easily accumulate and penetrate. The curvature directs moisture away from the terminal-resin interface, preventing popcorn phenomenon while maintaining manufacturing simplicity
Solution Approach 2:
The spherical surface geometry is formed in advance during the etching process to prevent moisture ingress before it can cause damage. This preliminary structural design creates a moisture-resistant interface that actively prevents harmful moisture penetration rather than merely resisting it after entry
3Device complexity
If the terminal surface area in contact with resin is small, then the terminal structure is simple, but the adhesion between terminal and resin is insufficient
Solution Approach 1:
The invention changes the surface area parameter by creating a spherical surface with radius R1, which increases the contact area between terminal and resin compared to a flat surface of the same footprint. This parameter change enhances adhesion strength while keeping the terminal structure simple and forming both features in a single etching process
Data Source
AI summary
A semiconductor device includes a leadframe, a semiconductor chip mounted on the leadframe, and an encapsulation resin covering the leadframe and the semiconductor chip. The leadframe includes a terminal having a pillar shape. The terminal includes a first end surface, a second end surface facing away from the first end surface, and a side surface extending vertically between the first end surface and the second end surface. The side surface is stepped to form a step surface facing away from the second end surface and having an uneven surface part formed therein. A first portion of the terminal extending from the first end surface toward the second end surface and including the step surface is covered with the encapsulation resin. A second portion of the terminal extending from the first portion to the second end surface projects from the encapsulation resin.