| 摘要 |
PURPOSE:To enable suppressing of a bubble detecting error to a very low proportion, by removing noise by subtractive computation of a light containing signals of a reference light and bubble. CONSTITUTION:Liquid 2 storaged in a liquid receptacle 1 is heated by a heater 3 to heat an LSI package 4. The inner gas of the LSI package 4 is heated to increase the internal pressure thereof. Gas (bubbles) 5 leaking through a defect spot comes up. Light emitted from a light source 7 is divided into two equal parts by a beam splitter 8, light 10 produces a bubble detecting light, a reference light 11 is caused to run in the proximity of the light 10 through a mirror 9, and simultaneously, is caused to pass so as to keep it away from the bubbles 5 and a funnel 6. The quantity of the light 10 and that of the reference light 11 are measured by a collecting element 12 and a collecting element 13 for reference light, respectively. The intensity of light caught by the collecting elements 12 and 13 is converted into a voltage or a current, and after it is subtracted by a subtrative computing device 14, it is amplified by an amplifier 15, and it further passes through a band-pass filter 16 to detect leak bubbles by means of a deciding device 17. |
