Exposure equipment

Whereas the eadiest fluorescent-dye pigments would last only 20 days outdoors in a screen-ink film, fade resistance has been improved to such an extent that some modem daylight-fluorescent coated panels stiU have useful color after nine months or mote in Florida sunlight in a 45° exposure tack facing south. The fluorescent layer is usually coated with an acrylic film containing a uv absorber. Indoor-accelerated exposure equipment is, of course, invaluable in the development of such systems. Better dyes and resins very likely will make possible fat mote stable coatings in the future. 

Accelerated exposure equipment may also be used to test for weatherfastness in plastic materials [106], The natural destructive agents inherent in weather are approximated by filtering the radiation emitted by the xenon arc lamp and by spraying the sample with water under standardized conditions [106], Test programs are designed to relate to actual outdoor exposure to rain and humidity. In a standard program, a 3 minute wet cycle typically alternates with a 17 minute dry period. Weatherfastness tests are carried out and evaluated like lightfastness tests the black panel temperature and other parameters are the same in both procedures. 

Weatherfastness tests on coatings have shown that prolonging the dry and wet periods, i.e., extending the usual 17 minute dry cycle to a full 102 minutes and the wet period to 18 minutes, affords results which correlate much better with the Florida outdoor exposure tests. The humidity that penetrates a layer is known to interact with the various components in the coating, adversely affecting the mechanical properties of the material. The above mentioned cycle apparently corresponds much better with the climatic conditions in areas like Florida. If recirculated water is used in accelerated exposure equipment, suspended particles may adhere to the surface of the coating, producing a thin film. This obviously has a detrimental effect on the test results. 

Standards exist for determining the light fastness of colored pigmented plastics in daylight and in xenon arc light, i.e. in accelerated exposure equipment, and for determining the weathering fastness. 

Long-term nitrous oxide exposure may also cause infertility. Several studies of dental workers and midwives who had been exposed to low levels of the gas in the workplace found that their fertility was reduced in direct relation to the level and length of exposure. Equipment to limit nitrous oxide levels can be installed in a doctor s office to reduce this risk. 

The double-side coated cyan-forming product was the most successful and satisfied an ever-increasing market. The paper products were supplied in a variety of sizes as well as rolls. No special effort was made by DuPont to manufacture exposure equipment, but there were many companies that offered such. These products were still very successful some 35 years after their introduction into the commercial market place. But there appeared new opportunities. 

The DQN resist system is able to resolve images much smaller than 0.5 Jim. Thus, the resists available today are not the limiting factor in defining device dimensions. In feet, the resolution limit that can be reached in a manufacturing environment is limited not by the intrinsic properties of the resist materials available but by the physical limitations of the exposure equipment and by practical issues that include contamination control, level-to-level alignment capability, etc. Consequently, resist materials research has been, and will continue to be, focused on devising material approaches to extending the resolution limits imposed by the physics of the available exposure equipment. 

As the physics and engineering of high-resolution exposure equipment advances with the advent of excimer-laser-powered, DUV projection printers... 

MacFarland. H. N. (1983). Design.s and operational characteristics of inhalation exposure equipments — A review. Futidani. Appl. Toxtcol 3, 603-613. 

Subsequent to the corrosive gas exposure, equipment intended for outdoor use should be exposed to cyclic high/low humidity (95/20 % RH) with the equipment powered. An appropriate exposure sequence is 12 h high, 12 h low for 20 days. 

Compatibility with Existing Application and Exposure Equipment... 

In the past, several photoresists were formulated for exposme at a visible wavelength,450 nm, using specialized exposure equipment—either visible lasers or magnified projection printing. More recently, laser direct imaging (LDI) based on the Ar+ laser ontpnt clnstered aronnd 360 nm has been commercialized. Conventional photoresists can be exposed on LDI eqnipment, bnt higher photospeed has been key to the productivity and economics of LDI. 

Noncontact Exposure Equipment Semicondnctor imaging demonstrated the yield limitations in using contact-exposure equipment. Noncontact methods had to be developed to achieve acceptable condnctor yield as critical dimensions decreased to 0.18 jum and below. 

Laser units are available for exposing photoresist that have been used for exposing solder mask. These solder masks may be spedaUy formulated to be sensitive to the laser wavelength. Laser imaging ehminates solder mask registration problems, bnt is not as prodnctive as conventional exposure. Equipment cost is very high compared to conventional lamp exposure equipment. 

Similar exposure equipment is available for flexible circuits. A collimated light source machine is recommended for high-density traces with pitches smaller than 50/mi to achieve a high yield. 

An engineering soludon to the delay time problem may lie in the use of automated, single-wafer processing exposure equipment, where the wafer is immediately postbaked, and possibly developed, after eiq)osure. While such an approach seems feasible, it would represent a major paradigm shift in the industry, which typically has expected the resist chemistry to adjust to the existing equipment. 

The concept of a contrast enhancement layer (CEL) is straightforward. All exposure equipment... 

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