X-ray or gamma ray systems or devices – Specific application – Fluorescence
Reexamination Certificate
1999-02-03
2001-01-16
Porta, David P. (Department: 2876)
X-ray or gamma ray systems or devices
Specific application
Fluorescence
C378S121000, C313S358000, C250S370060
Reexamination Certificate
active
06175612
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a small-sized fluorescent X-ray film thickness monitor to be installed in a manufacturing line in order to monitor for nickel electroless plating film thickness on aluminum substrate of a hard disc.
As hard disc density increases, there is a growing problem of base flatness or evenness in opposite surface film thickness of substrate electroless nickel plating. It is becoming important to monitor electroless nickel plating film thickness immediately after electroless nickel plating or before or after polishing in a manufacturing line. Conventionally, sampling inspections have been conducted with an off-line fluorescent X-ray gauge.
The conventional sampling inspection has involved a problem in that occurrence of a product rejection results in a rejection on a lot basis thus raising a rejection rate under recent severe criteria. Due to this, there has been a necessity to adjust working conditions to decrease the rate of rejection by conducting an in-line re-measurement for immediate feedback. In installing a fluorescent X-ray film thickness gauge in the production line of a coated part, there has been a dimensional problem of an X-ray generating system as well as a problem of fluttering of measurement samples. Therefore, it is an object of the present invention to provide a fluorescent X-ray monitor that is small in size and excellent in characteristic for in-line installation in the production line of a coated part for measuring the film thickness of the coating applied to the part.
SUMMARY OF THE INVENTION
In a conventional monitor, an X-ray tube
23
of a side window-type, which is shown in
FIG. 2A
, is immersed in an insulation oil
22
disposed in an oil tank
21
for discharge prevention and cooling purposes due to the use of high pressure. Accordingly, it has been impossible to decrease the size and to reduce the weight of the conventional monitor. In respect of this problem, by employing an end window-type X-ray tube having a casing
25
molded by silicone resin or the like for irradiating a coated part with a collimated X-ray beam, as shown in
FIG. 2B
, it is possible to decrease the size and reduce the weight of the monitor and to further place an X-ray generation point in a production line close to the sample as compared with the X-ray tube of the side window-type, thereby also improving the excitation efficiency.
In respect of fluttering in measurement samples, although a conventional monitor has conducted detection by placing a detector
31
for detecting electromagnetic waves irradiated by the sample in response to irradiation by the X-ray at a certain angle with respect to a primary X-ray irradiation axis
4
, as shown in
FIG. 3A
, and hence had an angular characteristic, it is possible to solve the fluttering problem by arranging an annular detector
31
coaxial to the irradiation axis
4
as shown in FIG.
3
B.
Also, because the annular type detector can afford to have a great solid angle and hence improve efficiency, it is possible to decrease an affection difference of an inverse square law on distance caused by increasing an irradiation-detection distance, i.e., a distance from a detection plane to a sample, and also to improve the distance characteristic.
REFERENCES:
patent: 3895250 (1975-07-01), Christgau et al.
patent: 5113421 (1992-05-01), Gignoux et al.
patent: 5574284 (1996-11-01), Farr
Adams & Wilks
Hobden Pamela R.
Porta David P.
Seiko Instruments Inc.
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