Insulating Coating Composition for Smooth Thick Film Formation
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Solution Overview
Problem
Insulating pastes containing glass powder face challenges in achieving a smooth coating surface due to poor fluidity, leading to air bubbles and unevenness, especially when forming thick coatings, as the viscosity increases during solvent drying and interactions between hydroxyl groups on the glass powder surface hinder smooth coating formation.
Innovation Solution
A composition comprising a first resin with a glass transition temperature ≤−20°C and a second resin with specific structures that improve fluidity by adhering to and breaking hydrogen bonds on the glass powder surface, along with a photopolymerization initiator for enhanced curing, allowing for smooth coating formation even at large thicknesses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a known insulating paste containing glass powder (20 parts by mass or more) is used for coating, then the coating thickness can be increased to 30 μm or more, but the coating surface becomes uneven with air bubbles due to poor fluidity
Solution Approach 1:
The patent changes the chemical composition parameters of the resin by specifying a glass transition temperature of ≤−20°C and a specific structural formula with particular R1, R2, and X groups. This parameter optimization improves the resin's fluidity characteristics, allowing the paste to level properly during drying even at coating thicknesses of 30 μm or more, thereby eliminating surface unevenness and air bubbles while maintaining the desired coating thickness.
Solution Approach 2:
The patent creates a composite resin system combining specific poly(meth)acrylate structures with controlled glass transition temperatures and specific molecular weight ranges. This composite material approach integrates multiple functional properties: the low Tg provides fluidity, the molecular weight control prevents excessive viscosity increase during drying, and the specific structural formula ensures proper adhesion and surface leveling, enabling smooth thick coatings to be formed.
2Volume of moving object
If the coating formation thickness is increased to 30 μm or more using a screen plate with large mesh diameter, then thicker coating can be applied, but air bubbles and unevenness occur noticeably
Solution Approach 1:
The patent optimizes the resin's glass transition temperature to ≤−20°C and controls the molecular weight within specific ranges (number average: 1,000-100,000; weight average: 10,000-500,000). These parameter changes ensure that the paste maintains appropriate viscosity characteristics during the drying process, enabling it to flow and level properly even when applied at thicknesses of 30 μm or more through screen printing with large mesh diameters, thereby preventing air bubble entrapment and surface unevenness.
3Reliability
If solvent drying is performed on insulating paste, then the coating is formed and cured, but viscosity increases and fluidity deteriorates causing poor surface smoothness
Solution Approach 1:
The patent specifies a glass transition temperature of ≤−20°C and controls the molecular weight parameters (number average: 1,000-100,000; weight average: 10,000-500,000) of the poly(meth)acrylate resin. These parameter optimizations ensure that during solvent drying, the resin does not undergo excessive viscosity increase that would prevent proper leveling. The low Tg maintains molecular mobility, and the controlled molecular weight prevents gelation, allowing the coating to achieve smooth surface finish while completing the drying and curing process reliably.
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 maintains fluidity during drying, reduces static viscosity, and provides a smooth coating surface with improved insulation reliability and solvent resistance, preventing insulation failures in electronic components.
Implementation Method 1
the first resin composition is a poly(meth)acrylate with a glass transition temperature Tg of ≤−20° C., and the second resin composition is a compound having structures represented by general formulae (1) and (2), below, one or more structures for each.
Implementation Method 2
a photopolymerization initiator for enhanced curing
Data Source
AI summary
A coating composition contains 5 parts by mass or more and 20 parts by mass or less (i.e., 5 to 20) of a first resin composition, 5 parts by mass or more and 20 parts by mass or less (i.e., 5 to 20) of a second resin composition, and 40 parts by mass or more and 65 parts by mass or less (i.e., 40 to 65) of an inorganic powder. The first resin composition is a poly(meth)acrylate with a glass transition temperature Tg of ≤−20° C., and the second resin composition is a compound having structures represented by general formulae (1) and (2), below, one or more structures for each. R1, in general formula (1), and R2, in general formula (2), are each independently a hydrogen atom or a methyl group. X, in general formula (2), is any substituent that is not a hydrogen atom.