Amorphous Silica Powder Magnetic Separation for Semiconductor Sealing
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Solution Overview
Problem
Current semiconductor sealing materials face challenges in achieving high insulation reliability and moldability due to contamination from magnetizable particles in amorphous silica powders, which can cause short circuits and wire flow issues, and existing methods for removing these particles are costly and inefficient.
Innovation Solution
An amorphous silica powder with specific particle size, sphericity, and magnetizable particle removal methods, including a magnetic separation process using high magnetic force screens and spray-drying, is developed to produce a resin composition that minimizes magnetizable contaminants and enhances the semiconductor sealing material's properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods (sulfuric acid treatment, organic solvent dispersion, hot water treatment) are used to remove magnetizable particles from amorphous silica powder, then magnetizable particle removal is achieved, but production cost increases and additional problems arise (re-contamination risk, sulfate ion contamination, organic solvent masking effect, powder aggregation)
Solution Approach 1:
The patent applies preliminary action by performing magnetic separation early in the production process, before the silica powder undergoes subsequent processing steps. The amorphous silica powder is mixed with water to form a slurry, and magnetic separation is performed on this slurry to remove magnetizable particles. This preliminary removal prevents contamination issues that would arise from later removal attempts, and avoids the need for costly acid treatment or organic solvent dispersion methods.
Solution Approach 2:
The patent extracts the harmful magnetizable particles from the amorphous silica powder through magnetic separation. By forming a slurry with water and applying magnetic fields, the magnetizable particles are separated from the non-magnetic silica powder. This extraction method is cleaner and more efficient than acid dissolution or organic solvent dispersion, as it removes only the contaminants without introducing additional contaminants or requiring complex subsequent processing steps.
2Reliability
If hot water treatment is used to remove magnetizable particles, then particle removal is achieved, but powder aggregation occurs during heating and drying, causing wire flow in semiconductor sealing
Solution Approach 1:
The patent uses water as a disposable medium for magnetic separation. The water is mixed with the amorphous silica powder to form a slurry for magnetic separation, then removed after the separation process. This simple, inexpensive medium achieves particle removal without causing aggregation, unlike hot water treatment which requires heating and drying that lead to powder aggregation and subsequent wire flow problems in semiconductor sealing applications.
3Quantity of substance
If fine particle size amorphous silica powder is used for semiconductor sealing, then filling density is improved, but magnetizable particle contamination from equipment surfaces increases
Solution Approach 1:
The patent performs magnetic separation as a preliminary step before the amorphous silica powder is used in semiconductor sealing applications. By forming a slurry with water and applying magnetic fields, magnetizable particles that may have contaminated the fine powder during production or handling are removed. This preliminary cleaning ensures that even fine particle size powders with high filling density do not contain harmful magnetizable contaminants that could cause short circuits.
Solution Approach 2:
The patent extracts magnetizable particles from the fine amorphous silica powder through magnetic separation. The slurry formation with water allows magnetic fields to effectively remove the contaminant particles. This extraction method is particularly effective for fine powders where contamination from equipment surfaces is more significant, as it removes the harmful particles without requiring changes to the powder's particle size or filling density.
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 resulting amorphous silica powder and resin composition significantly reduce the risk of short circuits and wire flow, achieving high insulation reliability and moldability in semiconductor sealing materials, suitable for miniaturized and high-density semiconductor applications.
Implementation Method 1
a magnetic separation zone in which 10 or more screens having an aperture of 0.5 mm or more and 15 mm or less and each having a magnetic force of 14000 gausses or more are vertically stacked, to remove magnetizable particles included in the amorphous silica powder
Implementation Method 2
feeding a water slurry containing the amorphous silica powder after removal of the magnetizable particles through a center portion of a two-fluid nozzle from a container set to 130°C or higher and 300°C or lower of inside temperature and having the two-fluid nozzle provided at the upper portion, and at the same time injecting dry air through an outer portion of the two-fluid nozzle to spray-dry the slurry
Data Source
AI summary
Provided are an amorphous silica powder having extremely high insulation reliability and capable of preparing a semiconductor encapsulant having high moldability, and a resin composition containing the same. The amorphous silica powder has an average particle size of 3 µm or more and 50 µm or less, wherein the percent retention of 250 µm or more by dry sieving is 5.0% by mass or less, and the number of magnetizable particles having a size of 45 µm or more measured by a specific method is zero.