Advanced Epoxy Resin Solder Paste Compositions
Innovative solutions for high-density semiconductor packaging and precision electronic assembly
The Evolution of Soldering Technology
Recently, with the miniaturization and increased functionality of electronic devices, there has been a constant demand for higher density in semiconductors and similar components. Consequently, welding processes have become essential bonding technologies. What is soldering paste for in this context? It serves as a critical material that enables these advanced bonding processes.
The welding process known as soldering is a method of joining two different materials by melting a low-melting-point metal at temperatures below 450°C. Recent developments in welding processes have moved toward the use of solder balls or solder bumps. Solder balls are solder components that provide electrical and mechanical connections between chips and substrates, taking the form of ultra-precise solder materials in small bead form that ultimately enable electrical signal transmission between chips and circuit boards.
What is soldering paste for in these advanced applications? It facilitates the bonding process by ensuring proper wetting and connection between components, even as electronic devices become increasingly miniaturized and complex.
The Role of Flux in Soldering Processes
During the soldering process, if an oxide film forms on the surface of the metal components to be joined, this oxide film acts as a barrier, preventing the molten metal used for bonding from wetting the pure metal, thus making proper bonding impossible. To prevent this phenomenon, flux is typically used in conventional bonding operations.
What is soldering paste for when considering flux functionality? It integrates the necessary flux components with solder materials, providing both the bonding medium and the oxide-removing properties in a single application. Flux destroys the oxide layer on the solder surface and prevents the formation of new oxide layers by isolating the metal surface from atmospheric contact during the bonding process, facilitating successful joining.
Oxide Prevention
Creates a protective barrier against atmospheric oxygen during soldering process
Surface Activation
Removes existing oxide layers to ensure proper metal-to-metal bonding
Wetting Enhancement
Improves molten solder flow and adhesion to component surfaces
Limitations of Conventional Methods
Traditional soldering methods using solder balls typically involve applying flux before installing the solder balls to remove oxide films on substrates or wafers. However, in these cases, flux residues remain at the soldering sites, which can cause circuit corrosion and disconnection.
What is soldering paste for in addressing these issues? Modern formulations are designed to minimize residue while maintaining effective fluxing action. To remove such residues, additional cleaning steps are required, but due to the miniaturization and increased density of electronic devices, removing flux residues left in soldering areas has become extremely difficult.
Furthermore, even when cleaning is feasible, the waste generated during the cleaning operation can cause environmental problems. Recently, an alternative process has been applied: after installing solder balls on a substrate or wafer, flux is applied using a dotting device on top of the solder balls. However, this approach also presents difficulties in uniformly applying flux due to the miniaturization of electronic devices.
Innovative Epoxy Resin Solder Paste Composition
In response to these challenges, our researchers have developed an epoxy resin solder paste composition with excellent wettability that can be uniformly applied to solder balls while minimizing flux residues. What is soldering paste for in this innovative solution? It represents a breakthrough in material science that addresses both performance and manufacturing challenges in advanced electronics.
Key Characteristics
The present invention is a composition comprising epoxy-based resins, with a viscosity of 10000cps to 30000cps and a contact angle of 35° to 40°. This unique combination of properties ensures optimal application and performance in high-precision soldering applications.
What is soldering paste for when formulated with these specific characteristics? It provides the ideal balance of flow properties and surface tension to ensure complete coverage of solder balls while maintaining precise placement and minimizing spreading beyond intended areas.
Viscosity Range: 10000-30000 cps
- Ensures proper adhesion to solder balls during application
- Prevents excessive flow that would compromise precision
- Maintains uniformity across multiple solder points
- Facilitates controlled application through various dispensing methods
Contact Angle: 35°-40°
- Provides optimal wetting without excessive spreading
- Ensures complete coverage of solder ball surfaces
- Promotes strong adhesion between components
- Facilitates proper heat transfer during reflow processes
Composition Details
The epoxy resin solder paste composition includes epoxy-based resins, curing agents, reducing agents, surfactants, and catalysts. Each component plays a critical role in achieving the overall performance characteristics. What is soldering paste for without this precise combination of ingredients? It would fail to provide the necessary balance of fluxing action, adhesion, and post-cure properties required in advanced electronic manufacturing.
Epoxy-Based Resins
The epoxy-based resins can be one or more selected from the group consisting of:
- Bisphenol A diglycidyl ether (DGEBA)
- Trifunctional epoxy resin (Tri-Glycidyl p-Aminophenol, TGAP)
- Tetrafunctional epoxy resin (TetraGlycidyl Diamine Diphenyl Methane, TGDDM)
Curing Agents
The curing agent can be one or more selected from the group consisting of amine family substances and anhydride family substances:
Amine-based:
- Meta-PhenyleneDi Amine (MPDA)
- Diamino Diphenyl Methane (DDM)
- Diamino Diphenyl Sulfone (DDS)
Anhydride-based:
- Methyl Tetra HydroPhthalic Anhydride (MTHPA)
- HexaHydro Phthalic Anhydride (HHPA)
- Other specialized anhydrides
The curing agent is preferably included at an equivalent ratio of 0.2 to 0.4 relative to the epoxy resin.
Reducing Agents
The reducing agent can be one or more selected from the group consisting of:
The reducing agent is preferably included at 5 to 15 parts by weight based on 100 parts by weight of the curing agent.
Surfactants & Catalysts
Surfactants:
One or more selected from:
- Nonionic surfactants
- Fluorine-based surfactants
- Perfluoroalkyl polyoxyethylene ethanol
- Fluorinated alkyl esters and others
Catalysts:
One or more selected from:
- Benzyl Dimethyl Amine (BDMA)
- BF3-MonoEthylAmine (BF3-MEA)
- Tris(dimethylaminomethyl)phenol (DMP-30)
- MethylImidazole (MI) and others
Optimal Component Ratios
In the epoxy resin solder paste composition, the reducing agent, surfactant, and catalyst are preferably included in the following proportions based on 100 parts by weight of the curing agent:
These precise ratios ensure the optimal balance of properties needed for effective soldering performance. What is soldering paste for without this careful formulation? It would lack the necessary combination of oxide removal, wetting ability, and curing properties required for modern electronic manufacturing.
Semiconductor Device Mounting Method
The application of our epoxy resin solder paste composition follows a precise process designed to maximize bonding efficiency while minimizing residue. What is soldering paste for in this process? It serves as both the bonding medium and the fluxing agent, streamlining the assembly process while improving results.
Preparation
Prepare a container holding the epoxy resin solder paste composition, as well as a device substrate and wiring substrate with attached solder balls. This step ensures all materials are properly conditioned and ready for the bonding process.
Application
Immerse part of the device substrate with attached solder balls into the container holding the epoxy resin solder paste composition to apply the composition to the solder balls. This immersion method ensures uniform coverage of each solder ball with the precise amount of paste.
Bonding and Heating
Join the device substrate with composition-coated solder balls to the wiring substrate, followed by a heating step. This heating process activates the flux components, removes oxides, and initiates curing of the epoxy resin, creating a strong, reliable bond.
Related Prior Art
Understanding what is soldering paste for in the context of previous developments helps appreciate the advancements in our composition. The following patents represent relevant prior art in the field:
Method and Apparatus for Applying Dry Flux on Metal Surfaces Before Soldering or Tin Plating
This patent describes a method for applying dry flux to metal surfaces prior to soldering or tin plating, focusing on pre-treatment processes to prepare surfaces for bonding.
Curable Flux Composition and Solder Paste Including the Same
This patent covers curable flux compositions and solder pastes incorporating them, representing an advancement in flux technology prior to our innovation.
Revolutionizing High-Precision Soldering
Our epoxy resin solder paste composition represents a significant advancement in soldering technology, addressing the critical challenges of miniaturization, residue formation, and bonding reliability. What is soldering paste for in the future of electronics manufacturing? It will continue to be an essential material enabling smaller, more powerful, and more reliable electronic devices through advanced bonding technologies.
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