Sintered Copper Joining for High-Temp Semiconductor Reliability
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Solution Overview
Problem
Current semiconductor devices face challenges in achieving reliable connections at high temperatures due to insufficient thermal conductivity and heat resistance in joining portions, particularly with sintered metal layers, and there is a need for lead-free joining materials that can withstand high-temperature operations.
Innovation Solution
A sintered metal layer formed from copper paste with flake-shaped copper particles oriented in parallel, ensuring a copper content of 65% or greater by volume, which enhances thermal conductivity and joining strength, and includes a structure that disperses thermal stress effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high-melting-point lead solder is used as a joining material for high-temperature operation, then the melting point is improved, but thermal conductivity and heat resistance become insufficient
Solution Approach 1:
The invention changes the material parameters by using copper particles instead of lead solder, achieving both high melting point and high thermal conductivity. The copper paste formulation with specific particle size distribution and organic vehicle enables sintering at temperatures suitable for semiconductor processing while maintaining excellent thermal and mechanical properties.
Solution Approach 2:
The invention creates a composite joining structure using copper particles combined with an organic vehicle that facilitates sintering. This composite approach allows the copper to form a sintered layer with optimized microstructure that simultaneously provides high melting point, high thermal conductivity, and strong adhesion to the semiconductor element.
2Reliability
If lead solder is used as a joining material, then connection reliability is maintained, but RoHS compliance is violated
Solution Approach 1:
The invention extracts and eliminates lead from the joining material while maintaining the essential functional properties. By using copper particles as the base material and developing a lead-free organic vehicle system, the invention removes the harmful substance (lead) while preserving connection reliability and achieving RoHS compliance.
3Strength
If sintered metal layer is formed for joining, then joining strength is improved, but thermal conductivity becomes insufficient
Solution Approach 1:
The invention optimizes the particle size distribution of copper particles in the paste formulation, using a combination of fine and coarse particles that pack efficiently during sintering. This parameter optimization creates a dense sintered structure with minimal porosity, simultaneously achieving high joining strength and high thermal conductivity.
Solution Approach 2:
The copper paste comprises copper particles combined with a specifically formulated organic vehicle that acts as a binder and sintering aid. This composite formulation ensures that during sintering, the copper particles form strong bonds while maintaining a dense microstructure that facilitates efficient heat conduction.
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 solution provides a semiconductor device with improved connection reliability and high-temperature operation capabilities, enabling large capacity and space-saving semiconductor elements by maintaining strong adhesion and thermal conductivity.
Implementation Method 1
a sintered metal layer, which includes a structure that is derived from flake-shaped copper particles oriented in approximately parallel to an interface between a first member or a second member and the sintered metal layer
Implementation Method 2
the sintered metal layer has excellent thermal conductivity and joining strength
Data Source
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AI summary
Provided is a joined body including: a first member; a second member; and a sintered metal layer that joins the first member and the second member. The sintered metal layer includes a structure that is derived from flake-shaped copper particles which are oriented in approximately parallel to an interface between the first member or the second member, and the sintered metal layer, and the amount of copper contained in the sintered metal layer is 65% by volume or greater on the basis of a volume of the sintered metal layer.