Evaluation of Shape/Coarse Particle Content of Spherical Silica Powder: Quality Control by Dynamic Image Analysis Method

Introduction

Silica powder is used in a wide range of fields, from encapsulants for semiconductors and other electronic components to paints and fillers. However, when coarse particles (foreign matter or aggregates) are unintentionally included in silica powder, they can cause forming defects, insulation defects, and electrical property defects in electronic components and defects such as strength reduction or unevenness in paint films when present in paint. Moreover, the shape of particles also influences fluidity and performance. Laser diffraction method (LD) and scanning electron microscopy (SEM) are used to evaluate the size and shape of silica powders. However, LD has low sensitivity for trace amounts of coarse particles, and in addition, it is theoretically impossible to acquire shape information, while SEM has the problems of a long measurement time due to its narrow observation field, and it is not possible to secure an adequate number of measured particles. On the other hand, because the dynamic image analysis (DIA) method can capture images of a large number of particles quantitatively in a very short time, DIA is suitable for rapid detection of trace amounts of coarse particles and evaluation of particle shape. The Shimadzu iSpect™ DIA-10 dynamic particle image analysis system (Fig. 1), which is based on the dynamic image analysis method, measures the size distribution, concentration, and shape of particles by imaging particles in liquid samples, and makes it possible to analyze tens of thousands of particles in a few minutes with an optical system that ensures minimal omission (imaging efficiency: 90 % or more). This article introduces an example in which the iSpect DIA-10 was used to evaluate the particle shape of silica powder and the contents of coarse particles before/after filtration.

November 20, 2020 GMT