Semiconductor Lead External Connection Recesses for Solder Mount Strength
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Solution Overview
Problem
Insufficient solder connection between semiconductor device leads and circuit board pads results in inadequate mount strength, leading to potential instability and reliability issues during semiconductor device mounting.
Innovation Solution
The semiconductor device design incorporates external connection portions on its leads with recesses and a center connection part, which enhance solder adhesion and distribution, ensuring sufficient soldering strength by positioning recesses towards the center and forming a plating layer on side surfaces for improved wettability, along with a restriction mechanism to prevent misalignment and enhance electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder is used to connect leads to circuit board pads, then electrical connection is achieved, but mount strength is insufficient
Solution Approach 1:
The external connection portion is divided into multiple connection regions (end connection parts and center connection part) separated by recesses. This segmentation allows solder to be distributed across multiple attachment points, increasing overall mount strength and reliability of the connection between semiconductor device and circuit board.
Solution Approach 2:
Different regions of the external connection portion have different local structures - end connection parts with recesses for strong solder anchoring and a center connection part for additional solder attachment. This local quality variation optimizes solder adhesion at different locations, significantly improving mount strength beyond what a uniform structure could provide.
2Strength
If leads are designed with simple external connection portions, then manufacturing is easier, but solder adhesion is insufficient
Solution Approach 1:
The lead's external connection portion is segmented into multiple regions by recesses, creating distinct end connection parts and a center connection part. This segmentation increases solder adhesion area and distribution without requiring complex three-dimensional structures, achieving improved solder adhesion with relatively simple planar geometry.
Solution Approach 2:
Resses are formed extending from the distal surface toward the encapsulation resin, creating depth dimension in the connection structure. This dimensional addition provides side surfaces for solder adhesion, significantly increasing effective solder attachment area without substantially increasing the planar footprint or 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
This design significantly increases the soldering strength and mount stability on the circuit board by ensuring adequate solder adhesion to the external connection portions and internal connection recesses, while preventing misalignment and improving electrical connection reliability.
Implementation Method 1
forming a plating layer on side surfaces for improved wettability
Data Source
AI summary
A semiconductor device includes a semiconductor element, leads, and an encapsulation resin covering a portion of each of the leads and the semiconductor element. Each of the leads includes an external connection portion projecting from a side surface of the encapsulation resin. The external connection portion of at least one of the leads has opposite ends in a width-wise direction that extends along the side surface of the encapsulation resin. The external connection portion includes two recesses arranged toward a center in the width-wise direction from the opposite ends. The two recesses extend from a distal surface toward the encapsulation resin. The opposite ends in the width-wise direction define an end connection part. The external connection portion includes a part between the two recesses defining a center connection part.