Leadframe-Free Semiconductor Terminal Structure Against Resin Separation
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Solution Overview
Problem
Semiconductor devices without lead frames face issues with terminal separation from the resin case, and conventional manufacturing methods are inefficient and require complex photolithography processes.
Innovation Solution
A semiconductor device design with terminals overlapping electrodes, covered by a sealing resin, and connected via conductive members, including multiple metal layers and columnar members fixed with solder, allowing for efficient manufacturing without lead frames.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If terminals are formed by plating on a metal base without using a lead frame, then the thickness of the terminals can be reduced to about 20 μm, but the terminals become more likely to separate from the resin case
Solution Approach 1:
The patent applies composite materials by forming a multi-layer terminal structure consisting of a first terminal layer (copper, 5-15 μm), a second terminal layer (nickel, 5-15 μm), and a third terminal layer (gold or palladium, 1-5 μm). This composite structure provides both reduced overall thickness and improved mechanical strength to prevent separation from the resin case.
Solution Approach 2:
The patent implements the nesting principle by creating a layered terminal structure where thinner terminal layers are formed on top of thicker base layers. The copper layer provides mechanical strength, the nickel layer provides adhesion, and the gold/palladium layer provides surface properties, with each layer nested within the structure to achieve both thinness and reliability.
2Device complexity
If conventional manufacturing methods without lead frames are used, then manufacturing complexity is reduced, but terminal separation issues arise
Solution Approach 1:
The patent applies preliminary action by forming the multi-layer terminal structure on the metal base before removing the base. This ensures that the terminals have sufficient mechanical strength and adhesion properties established in advance, preventing separation issues that would occur if terminals were formed after base removal.
Solution Approach 2:
The patent uses composite materials with the multi-layer terminal structure (copper-nickel-gold or palladium) to provide both the mechanical strength needed to prevent separation and the manufacturing efficiency of a lead-free process. The composite structure achieves reliability without requiring a lead frame.
3Manufacturing precision
If photolithography processes are used in conventional manufacturing methods, then manufacturing precision can be achieved, but manufacturing time and complexity increase
Solution Approach 1:
The patent replaces the photolithography process with a direct plating process. Instead of using photomasks, exposure, and development steps, the terminal patterns are formed directly through electroplating or electroless plating based on patterned seed layers, significantly reducing manufacturing cycle time while maintaining precision.
Solution Approach 2:
The patent extracts and removes the photolithography step from the manufacturing process. By using direct plating methods with pre-formed seed layers, the complex photolithography sequence (coating, exposure, development, etching) is eliminated, reducing both time and complexity while preserving pattern precision.
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 design prevents terminal separation and enhances manufacturing efficiency by reducing complexity and time, enabling thinner terminals with improved reliability and reduced defects.
Implementation Method 1
a sealing resin that covers the plurality of terminals and the semiconductor element
Implementation Method 2
a conductive connection member that contacts both the first terminal and the first electrode
Implementation Method 3
columnar members fixed with solder
Data Source
AI summary
A semiconductor device is provided with a semiconductor element having a plurality of electrodes, a plurality of terminals electrically connected to the plurality of electrodes, and a sealing resin covering the semiconductor element. The sealing resin covers the plurality of terminals such that a bottom surface of the semiconductor element in a thickness direction is exposed. A first terminal, which is one of the plurality of terminals, is disposed in a position that overlaps a first electrode, which is one of the plurality of electrodes, when viewed in the thickness direction. The semiconductor device is provided with a conductive connection member that contacts both the first terminal and the first electrode.