Evaluation of Concentration of Coarse Particles in High Concentration Silica Nanoparticle Slurry: Foreign Object Detection by Dynamic Image Analysis Method

Introduction

Silica is used in a wide range for fields, for example, as an encapsulant for semiconductors and other electronic components and as a filler in paints. When coarse particles (foreign matter, aggregates) are unintentionally included in silica, they can become a cause of defects such poor forming, insulation, or electrical properties in electronic components and reduced strength or unevenness of the paint film in paints. The techniques used in size evaluations of silica include laser diffraction method (LD) and scanning electron microscopy (SEM). However, as issues of these two methods, LD has low sensitivity for trace amounts of coarse particles, and SEM has a long measurement time owing to its narrow field of view in observation, and it is impossible to secure an adequate number of measurements. In addition, concentration information cannot be obtained with SEM. In contrast, the dynamic image analysis method makes it possible to acquire images of a large number of particles quantitatively and in a short time, and thus is suitable for rapid concentration evaluations and detection of trace amounts of coarse particles. The Shimadzu iSpect™ DIA-10 dynamic particle image analysis system (Fig. 1), which is based on this dynamic image analysis method, acquires images of the particles in liquid samples and measures the particle size distribution and particle concentration and shape. It is possible to analyze tens of thousands of particles in a few minutes with few missed particles (image acquisition efficiency: 90 % or higher). Moreover, since the iSpect DIA-10 uses the microcell method, it is also possible to measure cloudy samples which do not transmit light in a sample container. As a result, it is possible to shorten the time required for pretreatment and minimize the effect of dilution on samples by measuring the stock solution or a low-dilution solution. This article introduces an example in which the iSpect DIA-10 was used to evaluate the concentration of coarse particles in a silica nanoparticle slurry without diluting the stock solution.

August 1, 2020 GMT