Reaction Solder Composite for High-Temperature Power Electronics
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Solution Overview
Problem
Existing power electronics face thermal challenges due to high current levels and operating temperatures, leading to degradation of solder connections, especially at temperatures above 175°C, where traditional solders fail to provide reliable electrical and mechanical properties, and lead-containing solders are restricted by environmental regulations.
Innovation Solution
A layered composite is formed using a reaction solder with a base solder and an alloy (AgX, CuX, or NiX) where the alloy's melting temperature is higher than the base solder's, promoting the formation of an intermetallic phase between layers with different melting points, ensuring a stable, lead-free connection that compensates for thermal expansion differences and maintains conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If lead-free hard solder is used for high-temperature connections, then the operating temperature range is improved, but the processing temperature becomes too high for many electronic components
Solution Approach 1:
The solder alloy is segmented into multiple phases with different melting points: a base solder phase (lower melting point) and a reaction phase containing high-melting-point particles (higher melting point). This allows the solder to operate at high temperatures while processing at lower temperatures, as the base solder melts first for joining while the reaction phase remains solid during processing.
Solution Approach 2:
The invention changes the compositional parameters of the solder alloy by incorporating particles with different melting points (at least 100°C difference) into the base solder. This parameter modification enables the solder to exhibit both low processing temperature (via base solder melting) and high operating temperature resistance (via reaction phase formation).
2Ease of manufacture
If silver-containing sintered joints are used for low-temperature joining, then the processing temperature is reduced, but thermomechanical stresses and cracks occur under thermal cycling
Solution Approach 1:
The solder alloy is designed as a composite material combining a base solder matrix with dispersed high-melting-point particles. This composite structure provides both the low processing temperature advantage (from base solder) and high reliability under thermal cycling (from the reaction phase that forms intermetallic compounds resistant to thermomechanical stress).
Solution Approach 2:
The invention converts the potential harm of high thermomechanical stresses into a benefit by designing the reaction phase to form intermetallic compounds that are specifically resistant to such stresses. The particles that would normally be vulnerable to thermal stress actually create a protective reaction phase that enhances reliability.
3Ease of manufacture
If traditional soft solder is used for connections, then the processing temperature is kept low, but the electrical and mechanical properties deteriorate at high operating temperatures
Solution Approach 1:
The high-melting-point particles are pre-incorporated into the base solder before the soldering process. During processing, these particles react with the base solder to form intermetallic compounds that preliminarily establish a stable structure capable of withstanding high operating temperatures, preventing property deterioration before it occurs.
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 stable, high-temperature electrical and thermal connection with improved thermal and electrical conductivity, suitable for devices with high current densities and temperature loads, while avoiding the use of lead and reducing processing temperatures for energy efficiency and cost-effectiveness.
Implementation Method 1
By interdiffusion and/or diffusion, a connection that is stable at high temperatures can be formed at temperatures that are already significantly lower than the melting temperature
Implementation Method 2
After a temperature treatment of the layer arrangement a region with at least one intermetallic phase is formed between the first layer and the second layer
Data Source
Figure 1~2
AI summary
Laminated composite (10) comprising at least one electronic substrate (11) and an arrangement of layers (20, 30) made up of at least a first layer (20) of a first metal and/or a first metal alloy and of a second layer (30) of a second metal and/or a second metal alloy adjacent to this first layer (20), wherein the melting temperatures of the first and second layers are different, and wherein, after a thermal treatment of the arrangement of layers (20, 30), a region with at least one intermetallic phase (40) is formed between the first layer and the second layer, wherein the first layer (20) or the second layer (30) is formed by a reaction solder which consists of a mixture of a basic solder with an AgX, CuX or NiX alloy, wherein the component X of the AgX, CuX or NiX alloy is selected from the group consisting of B, Mg, Al, Si, Ca, Se, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Y, Zr, Nb, Mo, Ag, In, Sn, Sb, Ba, Hf, Ta, W, Au, Bi, La, Ce, Pr, Nd, Gd, Dy, Sm, Er, Tb, Eu, Ho, Tm, Yb and Lu and wherein the melting temperature of the AgX, CuX or NiX alloy is greater than the melting temperature of the basic solder. The invention also relates to a method for forming a laminated composite (10) and to a circuit arrangement containing a laminated composite (10) according to the invention.