Jettable Solder Mask Composition for High-Temperature PCB Soldering
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Solution Overview
Problem
Ink jet printing of solder mask compositions for printed circuit boards faces challenges due to viscosity restrictions, which can be overcome by using high viscosity inks, and compatibility with high temperature soldering processes while maintaining physical properties, especially with UV curable inks.
Innovation Solution
A jettable composition comprising a reactive monomer or prepolymer with epoxy or oxetane functional groups, a free radical polymerizable compound, a thermal cross-linking agent, and a radical initiator, which allows for high viscosity inks suitable for ink jet printing and maintains properties for high temperature soldering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the viscosity of ink jet solder mask composition is increased to reduce diluent content, then the nonvolatile content and film thickness are improved, but the ink jet printability deteriorates due to viscosity restrictions of printhead
Solution Approach 1:
The patent changes the chemical composition parameters of the ink by incorporating epoxy resin, oxetane resin, and their derivatives along with specific diluents and catalysts. This allows the ink to achieve higher nonvolatile content (15-40%) while maintaining printability through controlled viscosity via the specific combination of reactive diluents and crosslinking agents that adjust flow properties without sacrificing solids content.
Solution Approach 2:
The patent creates a composite solder mask composition integrating multiple resin systems (epoxy and oxetane), crosslinking agents, catalysts, and specialized diluents. This composite structure enables the ink to exhibit both high nonvolatile content for adequate film thickness and controlled rheological properties for ink jet printability, resolving the contradiction between quantity of substance and ease of operation.
2Strength
If UV curable inks are used to achieve rapid cure and high crosslinking degree, then chemical resistance and mechanical properties are improved, but compatibility with high temperature soldering process deteriorates
Solution Approach 1:
The patent modifies the chemical composition by incorporating epoxy and oxetane resins with high thermal stability, along with specific crosslinking agents that create thermally resistant networks. The formulation includes heat stabilizers and oxidation-resistant components that maintain the mechanical properties achieved through UV curing while enabling compatibility with high temperature soldering processes up to 260°C or higher.
Solution Approach 2:
The patent develops a composite curable composition that combines UV-curable acrylate or vinyl ether groups with thermally stable epoxy and oxetane resin systems. This dual-function composite material achieves rapid UV curing for excellent mechanical properties and chemical resistance, while the epoxy/oxetane backbone provides thermal stability for soldering process compatibility, resolving the contradiction between strength and temperature resistance.
3Ease of operation
If the ink is diluted with volatile solvent to achieve low viscosity, then ink jet printability is improved, but the nonvolatile content is reduced making it difficult to attain sufficient film thickness
Solution Approach 1:
The patent replaces volatile solvent dilution with a controlled system using reactive diluents (epoxy and oxetane resins) and catalysts that maintain lower viscosity without sacrificing nonvolatile content. The formulation achieves printability through controlled molecular weight and chain flexibility of the resin components rather than volatile solvent content, enabling high nonvolatile content (15-40%) to be maintained while achieving adequate flow properties for ink jet deposition.
Solution Approach 2:
The patent eliminates the need for volatile solvents that evaporate during drying, replacing them with non-volatile reactive diluents that remain in the final cured film. This approach avoids the loss of nonvolatile content associated with solvent evaporation and eliminates flammability and toxicity hazards, while still achieving the viscosity reduction necessary for ink jet printability.
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 composition achieves effective film thickness and maintains mechanical and chemical resistance, ensuring compatibility with high temperature soldering processes and reducing process steps and costs.
Implementation Method 1
a free radical polymerizable compound; and a radical initiator
Implementation Method 2
a reactive monomer, oligomer or prepolymer containing at least one epoxy or oxetane functional group; and a thermal cross-linking agent
Data Source
AI summary
A jettable composition is described, comprising a reactive monomer, oligomer or prepolymer containing at least one epoxy or oxetane functional group; a free radical polymerizable compound; a thermal cross-linking agent; and a radical initiator, along with an electronic device having the composition jetted thereon and a method of manufacturing an electronic device.