| 摘要 |
<p>PURPOSE: To reutilize a wafer case, without throwing it away by counting the number of particles in pure water again to obtain an increase in the number of particles after shaking and evaluating the cleanness of an internal housing member from the increased number. CONSTITUTION: After treatment in an ultrasonic tank with pure water 2 filling a vessel 8, the water 2 is drained out, a wafer basket 53 is put in the vessel 8, the water 2 is again poured until its surface reaches a position about 1cm below from the top of the basket and becomes stable and then the number of particles is measured by a particle meter 4. A vibrator 5 applies a low-frequency vibration for a certain time, the number of particles in the water 2 is again counted to obtain the number of increased particles after vibration, thereby evaluating the cleanness of the internal housing member, wafer case. Thus, the case is reutilized, without throwing it away.</p> |
