Solder Paste Block Copolymer Burnout Stability
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Solution Overview
Problem
Existing solder pastes face challenges in achieving good burnout properties, low toxicity, fire safety, storage stability, and suitable adhesion to substrates, particularly when used in soldering processes involving high temperatures and diverse processing methods.
Innovation Solution
A solder paste composition comprising metal powders with a melting temperature of 1500°C or less, combined with block copolymers having styrene and ethylene, propylene, or isoprene blocks, and an organic medium such as hydrocarbons with 10-15 carbon atoms, along with optional fluxes and additives like oxidizing agents, to enhance burnout behavior and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional organic polymers and inorganic fillers are used in solder paste, then storage stability is improved, but burnout properties and fire safety deteriorate at soldering temperatures
Solution Approach 1:
The patent changes the chemical composition parameters of the organic polymer to a specific copolymer containing styrene and isoprene blocks with defined molecular weight and composition ratios. This parameter change enables the material to maintain stability during storage while achieving excellent burnout properties at soldering temperatures, resolving the contradiction between storage stability and fire safety.
Solution Approach 2:
The patent uses a composite copolymer structure combining styrene and isoprene blocks in specific ratios (70-90 wt% styrene, 10-30 wt% isoprene). This composite material structure provides both the storage stability of conventional polymers and the improved burnout properties needed for fire safety, eliminating the need to choose between the two opposing requirements.
2Ease of operation
If metal powders with low melting temperature are used, then soldering processability is improved, but adhesion to substrate and overall performance deteriorate
Solution Approach 1:
The patent specifies precise parameter ranges for the copolymer including molecular weight (60,000-90,000 g/mol), styrene content (70-90 wt%), and isoprene content (10-30 wt%). These parameter optimizations enable the solder paste to maintain excellent adhesion to substrates while ensuring proper flow and wetting during the soldering process, resolving the contradiction between processability and reliability.
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 solder paste exhibits improved burnout properties, low toxicity, and excellent adhesion, ensuring reliable soldering performance with reduced fire hazards and extended storage stability, while maintaining suitable viscosity and adhesion to substrates.
Implementation Method 1
The organic medium is a hydrocarbon or hydrocarbon mixture that is liquid at room temperature... which evaporate or burn essentially without leaving any residue at the soldering temperatures
Implementation Method 2
The solder paste... have good adhesion to the substrate
Data Source
AI summary
Solder paste comprises (a) at least one metal powder suitable as solder, (b) at least one copolymer comprising at least one styrene block and at least one block of ethylene, propylene, isoprene, butadiene and/or their hydrogenated equivalents, and (c) an organic medium. An independent claim is also included for a structure comprising a layer of the above solder paste on a substrate; #a soldered article obtainable by applying the solder paste on a substrate, applying a connection partner on the substrate, where the connection partner exhibits contact with the solder paste, and carrying out heat treatment; #soldering a substrate with a connection partner, comprising (i) providing a substrate, a connection partner and the above solder paste, (ii) applying the solder paste on the substrate, connection partner or on both the solder paste and the connection partner, (iii) optionally drying the solder paste, (iv) contacting the substrate and the connection partner with each other such that the solder paste is at least partially arranged between the substrate and the connection partner, and (v) carrying out heat treatment of the substrate, connection partner, solder paste or their combinations; and #a structure comprising a partial or complete layer which comprises the components (a) and (b), applied on a substrate.