Bimodal Spherical Inorganic Powder for Flowable Encapsulation
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Solution Overview
Problem
Highly filled semiconductor encapsulating materials with inorganic powders face issues of reduced flowability and increased particle aggregation, leading to poor yield and potential defects in electronic devices.
Innovation Solution
A spherical inorganic powder with a specific particle size frequency distribution having two peaks within prescribed ranges, along with a ratio of frequencies at local maximum values, is used to prevent aggregation while maintaining excellent flowability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fill rate of inorganic powder in resin is increased to improve solder heat resistance, moisture resistance, and mechanical strength, then the functional performance is improved, but the flowability of the material deteriorates, making it difficult to penetrate between chip and substrate
Solution Approach 1:
The inorganic powder is segmented into multiple particle size ranges with distinct peaks (first peak at 0.1-0.6μm, second peak at 1.5-5.0μm). This segmentation allows different particle sizes to occupy different spaces, with fine particles filling gaps between larger particles, thereby maintaining high fill rate while preserving flowability through optimized particle packing.
2Ease of operation
If fine powder or ultrafine powder with particle diameter smaller than 1 μm is added to suppress decreases in flowability, then the flowability is improved, but the particles tend to aggregate due to their extremely small particle diameters, causing dispersion deficiencies
Solution Approach 1:
The invention applies local quality by assigning different particle size characteristics to different portions of the powder distribution. The first peak (0.1-0.6μm) provides flowability enhancement locally, while the second peak (1.5-5.0μm) provides structural stability and prevents aggregation. The controlled ratio (1.5-10.0) between these peaks ensures that fine particles do not dominate and cause aggregation, while still providing sufficient flowability improvement.
3Productivity
If aggregated particles increase in the resin composition, then the yield of semiconductor encapsulating material deteriorates and defects or short-circuits occur, but preventing aggregation requires complex particle size control
Solution Approach 1:
The invention changes the particle size distribution parameters by defining specific peaks and their ratio range (1.5-10.0). This parameter control approach transforms the complex aggregation problem into a manageable specification: maintaining the first peak at 0.1-0.6μm, second peak at 1.5-5.0μm, and their frequency ratio within 1.5-10.0. This simplifies quality control while effectively preventing aggregation and ensuring high yield.
Data Source
AI summary
A spherical inorganic powder having, in a particle size frequency distribution, a first peak having a local maximum value in a particle size region from 0.1 μm or larger to 0.6 μm or smaller, and a second peak having a local maximum value in a particle size region from 1.5 μm or larger to 5.0 μm or smaller, wherein a value of a ratio of a frequency at the local maximum value of the second peak to a frequency at the local maximum value of the first peak is 1.5 or higher and lower than 10.0.