Semiconductor Terminal Recess Plating for Reliable Solder Fillets
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Solution Overview
Problem
Existing semiconductor devices face challenges in ensuring reliable soldering and preventing defective soldering when mounted on a wiring board, particularly due to variations in terminal design and plating layers.
Innovation Solution
The semiconductor device incorporates a terminal design with a recessed plating section on the terminal portions exposed from the sealing resin, ensuring proper solder adhesion and preventing solder from flowing beyond the recess, thus enhancing soldering reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a plating layer is applied to the terminal portions exposed from the sealing resin, then the solderability of the terminals is improved, but solder may flow beyond the terminal surface causing defective soldering
Solution Approach 1:
The terminal surface is segmented into different functional zones: a recessed portion that confines solder and a protruding portion that remains exposed. This segmentation prevents solder from flowing beyond the terminal surface while maintaining good solderability in the recessed area.
Solution Approach 2:
Different portions of the terminal are given different structures and plating treatments. The recessed portion receives a plating layer to enhance solderability, while the protruding portion remains unplated to act as a solder stop barrier. This local differentiation resolves the contradiction between achieving good solder adhesion and preventing solder overflow.
2Ease of manufacture
If the terminal surface is made flat, then the manufacturing process is simplified, but solder fillet formation becomes inconsistent
Solution Approach 1:
The recessed portion is formed on the terminal surface before the plating process. This preliminary structural preparation creates defined areas for solder confinement, ensuring consistent solder fillet formation during subsequent soldering operations without requiring complex post-processing.
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 proposed solution effectively prevents defective soldering by ensuring consistent solder fillet formation across the terminal surfaces, thereby improving the reliability and integrity of the semiconductor device's mounting on a wiring board.
Implementation Method 1
ensuring proper solder adhesion and preventing solder from flowing beyond the recess
Data Source
AI summary
A semiconductor device includes a semiconductor element, a sealing resin covering the semiconductor element, a terminal electrically connected to the semiconductor element and protruding from the sealing resin in a first direction orthogonal to a thickness direction, and a plating layer located on the terminal. The terminal includes an end surface at a distal end protruding from the sealing resin, a first surface facing a first side in the thickness direction, and a recess recessed from both the end surface and the first surface. The plating layer includes a recess plating section located on at least a portion of the recess.