Method for producing a solder connection
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Solution Overview
Problem
Existing methods for producing soldered connections face challenges such as high temperature requirements that exceed the temperature resistance of many carriers, difficulties with low-temperature conductive pastes, and the need for expensive wet-chemical intermediate steps, which restrict the choice of substrates and affect the reliability of the connections.
Innovation Solution
A method involving the additive application of a conductor layer and solder using printing processes, where metal particles are coated with a noble metal coating through a noble metal salt or oxide, allowing for stable connections without sintering and eliminating the need for intermediate wet-chemical steps, utilizing screen printing and a reflow soldering process with low-temperature solders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sintering is used to create a conductive layer from metal particles, then the conductive layer is suitable for soldering, but high temperatures are required that exceed the temperature resistance of many carriers
Solution Approach 1:
The patent changes the key parameter from high-temperature sintering to low-temperature processing by using a different mechanism (metal stearate decomposition and reduction) to create the conductive layer, enabling processing below 250°C that is compatible with temperature-sensitive carriers
Solution Approach 2:
The patent utilizes phase transitions of metal stearate (from solid through melting and decomposition to metallic reduction) to transform the conductor layer in situ, eliminating the need for high-temperature sintering while still achieving a solderable conductive surface
2Temperature
If low-temperature conductive paste is used to avoid high temperatures, then carrier temperature resistance is not exceeded, but the organic binder makes the conductor layer difficult to wet with liquid solder
Solution Approach 1:
The patent performs preliminary action by incorporating metal stearate into the conductor layer before soldering, which then decomposes and reduces to metal during the soldering process itself, prepping the surface for optimal solder wetting without requiring separate treatment steps
Solution Approach 2:
The patent uses metal stearate as an intermediary substance that bridges the gap between the organic binder-based conductor layer and the solder, decomposing to provide a metallic surface that is readily wettable by solder while maintaining compatibility with low-temperature processing
3Reliability
If flux is used to remove oxides and support solder infiltration, then soldering is improved, but the flux has a negative effect on the printability of the conductor layer
Solution Approach 1:
The patent extracts the oxide removal function from the flux and assigns it to the metal stearate component, which decomposes and reduces oxides in situ during the soldering process, thereby eliminating the harmful impact of flux on printability while maintaining oxide removal capability
Solution Approach 2:
The patent implements self-service by incorporating the oxide removal functionality directly into the conductor layer material (metal stearate), which automatically performs the oxide removal task during the soldering process without requiring separate flux application
4Reliability
If wet-chemical intermediate steps are used to galvanically reinforce printed conductors, then soldering reliability is improved, but the process becomes expensive and complex
Solution Approach 1:
The patent merges multiple functions (conductor formation, oxide removal, and soldering preparation) into a single integrated process step where metal stearate decomposition and reduction occurs during the soldering reflow process, eliminating the need for separate wet-chemical reinforcement steps
Solution Approach 2:
The patent赋予 metal stearate multiple functions: it serves as a binder component in the conductor paste, an oxide removal agent during heating, and a surface preparer for soldering, thereby replacing multiple separate process steps with a single multi-functional material
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
Enables stable and reliable soldered connections on temperature-sensitive substrates without sintering, using low-temperature solders and eliminating the need for expensive intermediate wet-chemical steps, allowing for a wide range of substrate compatibility and improved printability.
Implementation Method 1
a soldering agent comprising a noble metal salt or a noble metal oxide is printed onto the conductor layer by means of a printing process, from which a noble metal is released to form the noble metal coating
Implementation Method 2
The solder is melted and then solidifies to form the soldered joint
Data Source
Figure 1A~1G
AI summary
In a method for producing a soldered joint (117) between a substrate (110) and a component (116), a conductive layer (112A, 112B) containing metal particles is printed onto a surface (111) of the substrate (110) using a printing process. A soldering compound (115) is then printed onto this conductive layer (112A, 112B) using a printing process. The substrate (110) is mounted with the component (116) so that the component (116) is in direct contact with the soldering compound (115). The soldering compound (115) is melted and then solidifies, forming the soldered joint (117). Before the soldering compound (115) is printed, the metal particles of the conductive layer (112A, 112B) are coated with a precious metal coating (114). For this purpose, a soldering agent (113) comprising a precious metal salt or a precious metal oxide is printed onto the conductor layer (112A, 112B) using a printing process.A precious metal is released from the precious metal salt or the precious metal oxide, forming the precious metal coating (114).