Ti-Al-NiV Layer Stack for Corrosion-Resistant Solder Joints
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Solution Overview
Problem
Existing soldering methods often result in inter-metallic phases with insufficient corrosion resistance, leading to unreliable solder connections between semiconductor chips and substrates.
Innovation Solution
A method involving the sequential deposition of Ti, Al, and NiV layers on a substrate, followed by tempering to form inter-metallic phases, which enhances corrosion resistance and stability of the solder connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional soldering methods are used to join semiconductor chips and substrates, then the soldering process is simple and fast, but the corrosion resistance of inter-metallic phases is insufficient leading to unreliable connections
Solution Approach 1:
The solder connection structure is segmented into multiple functional layers: a base solder layer, an intermediate layer containing first inter-metallic phases, and a top layer containing second inter-metallic phases. This segmentation allows each layer to perform specific functions, with the intermediate layer providing corrosion resistance and the top layer enhancing mechanical stability, thereby resolving the contradiction between reliability and structural simplicity.
Solution Approach 2:
The invention employs composite inter-metallic phase structures where different inter-metallic phases are formed in distinct layers. The first inter-metallic phases in the intermediate layer provide corrosion resistance, while the second inter-metallic phases in the top layer provide mechanical strength. This composite approach enables the solder connection to simultaneously achieve both corrosion resistance and mechanical reliability without excessive structural complexity.
2Reliability
If conventional soldering is performed without intermediate layers, then the manufacturing process is simple, but the solder connection may break off due to insufficient corrosion resistance
Solution Approach 1:
The method performs preliminary formation of inter-metallic phases through a controlled tempering process before final soldering. By pre-forming the intermediate layer with first inter-metallic phases and the top layer with second inter-metallic phases through a single tempering step at 200-400°C, the structure is prepared in advance to ensure corrosion resistance and mechanical stability, thereby maintaining ease of manufacture while improving reliability.
Solution Approach 2:
The invention utilizes parameter changes in the tempering process, specifically controlling the temperature range (200-400°C) and atmosphere to selectively form different inter-metallic phases in different layers. This parameter control enables the simultaneous formation of corrosion-resistant phases in the intermediate layer and mechanically stable phases in the top layer, achieving enhanced reliability without significantly complicating the manufacturing process.
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 method forms stable inter-metallic phases that improve the corrosion resistance and reliability of solder connections, preventing breakage and ensuring durable electronic module assembly.
Implementation Method 1
tempering in a way that at least one inter-metallic phase is formed between at least two metals of the group containing Ti, Al, Ni, and V
Implementation Method 2
inter-metallic phases can be formed between two or more of the metallic materials employed on either sides of the joint
Data Source
AI summary
In one embodiment method, a first Ti based layer is deposited on the substrate. An intermediate Al based layer is deposited on the first layer, a second NiV based layer is deposited on the intermediate layer, and a third Ag based layer is deposited on the second layer. The layer stack is tempered in such a way that at least one inter-metallic phase is formed between at least two metals of the group containing Ti, Al, Ni and V.