3. Equipment

The UV/Ozone unit is composed of a short-wavelength UV lamp as main device.
Currently low-pressure mercury lamp and xenon excimer lamp are most suitable.
However, the 172nm Xe-excimer lamp can hardly be used for three-dimensional products because it is absorbed intensively by oxygen and its effective irradiation distance is extremely short at 0 - 3mm.
The low-pressure mercury lamp can also be used for three-dimensional products because its effective irradiation distance has a wide range of 0 - 20mm.
Both lamps have nearly the same capacity, and the low-pressure mercury lamp is dedicatedly used for modification of the UV/Ozone method.
The ozone concentration necessary for surface treatment is so low at 100-300ppm that only the ozone generated by UV lamp will be enough, except for the ashing of photo-resist of substrate which requires highly concentrated ozone.
There has been no sufficient information available yet on the above-mentioned technology.
Therefore, particularly elaborate experiments are absolutely necessary before you judge whether to employ the technology or not.
Various testing devices have been developed and available for that purpose now.
Some of such devices are shown in Fig. 9 to 14.

Clockwise from top of left,Fig 9 & 10. Table top unit for experiment, Exposure area=150mm2~A4 size.		Fig 11.Experimental unit with a scanning light source, cost effective unit
Fig 12.High end automatic unit.	Fig 13.Simple model with drawer tray.	Fig 14.Both side exposure type unit.

As the electronic circuit boards or optical lens and prism are small-sized, in many case experimental machines are used for a small-lot production.
Various types of production facilities ranging from small-lot to mass production scales are now available.
A terminal tab cleaning device for liquid crystals or plasma TV priced at 70 million yen per unit is being manufactured.

Fig 15.16.UV/Ozone dry cleaner for quartz oscillators and pick-up lens of CD's.

4. Practical Example of UV/Ozone Process

No market statistics on the UV/Ozone process are available now, but it is estimated that the process is used most popularly for cleaning purposes, accounting for over 80% of surface treatments as a whole.
Among the applications for cleaning, more than 80% is for the production process of liquid crystal elements, of which business is estimated to amount to 20 billion yen as the author personally guesses.
In the wake of applications to liquid crystal products, the process is extensively applied to semiconductor exposure plates, optical lens and prism, quartz oscillators or IC element lead frames.
Recently even connection terminals of liquid crystal or plasma TV are being cleaned by the UV/Ozone process. (Fig. 17)

Fig 17.UV/ozone dry cleaner for connection terminal of LC or plasma TV.	Fig 18.UV/Ozone surface processor of the substrate film of flexible multilayer micro PCB

In terms of sales amount there is overwhelmingly more business in cleaning than in modification.
On the contrary, modification has a wider variety in practical applications than cleaning. Highly evaluated is the modification case of automobile bodies, especially that of engineering plastics around their engines.
However, as manufacturers keep confidential their production procedures, practical applications in such containment remain unrevealed.
This obstruction keeps the development of application from being evaluated as openly as seen in the cleaning application.
Among the prospective applications flexible multilayer printed circuit boards and substrate film treatments are included. (Fig. 5, 6 & 18)
The UV/Ozone process is effective to not only advanced products but also successfully to the processes in the general industrial products like an aquarium tank. (Fig. 7)
The aforementioned track coil compact for the magnetic levitated super-train is molded by epoxy resin, and has a structure for the outdoor use which requires a coating finish.
Under normal circumstances the sandblast process should be adopted for surface treatments, but the construction includes so many sites in the extremely bad environments filled with sandy dust.
The UV/Ozone process is successful also as an alternative of the low-tech sand-blast method.

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