Dry development

Another phenomenon is so called two-side filling of one-side closed conical capillaries with liquid [5]. On the one hand the more penetrant is trapped by the defect the wider indication will appear. Contrariwise it is almost impossible to extract a penetrant from the completely filled surface defects by dry developer [6]. In this study we propose the theory of the phenomenon. Besides experimental results of the investigation of two-side filling with various penetrants of conical capillaries are presented. Practical recommendations to optimize liquid penetrant testing process are proposed. 

Let us consider the calculation of sensitivity threshold in the case when the cracks are revealing by PT method. Constant distance H between crack s walls along the whole defect s depth is assumed for the simplicity. The calculation procedure depends on the dispersity of dry developer s powder [1]. Simple formula has to be used in the case when developer s effective radius of pores IC, which depends mainly on average particle s size, is smaller than crack s width H. One can use formula (1) when Re is small enough being less than the value corresponding maximum sensitivity (0,25 - 1 pm). For example. Re = 0,25 pm in the case when fine-dispersed magnesia oxide powder is used as the developer. In this case minimum crack s width H that can be detected at prescribed depth lo is calculated as... 

The case considered above corresponds to R < H. The calculation using formula (1) gives the next results. For example, consider the thickness of dry developer layer h = 20 pm. In the absence of sedimentation process our product family (penetrant and developer indicated above) could not detect the cracks with the depth lo < 1,33 mm of any widths. Nevertheless due to the sedimentation one can get the decrease of developer s thickness from h = 20 pm till h s 5 pm. As a result, our product family can ensure the detection of the cracks with H > 2,3 pm even with very small length lo = 0,4 mm. At the same time if lo = 1 mm, then the cracks with extremely small width H > 0,25 will be revealed. 

The thickness of dry developer s layer is substantially smaller in a zone imbibed by a penetrant due to the process of particles sedimentation. Reduced thickness h of imbibed zone can be 80% smaller than the thickness h of dry one. It must be taken into account in the calculations of PT characteristics in the frame of the theory [1-3]. 

If the well is completed for production it is classified as an oil or gas development well. If the well is not completed for production, it is classified as a dry development hole. 

Willemer, H. Measurements of temperature, ice evaporation rates and residual moisture content in freeze-drying. Developments in Biological Standardization, Vol. 74, p. 123-136. Acting Editors Joan C. May, F. Brown, S. Karger AG, CH-4009 Basel (Switzerland), 1992... 

Application to Dry-Developed Single-Layer Deep-UV Resists... 

The latest addition to this list of dry developing resist materials is a contribution from IBM s San Jose Research Laboratory (66-67) that evolved from efforts to design positive-tone resist materials that incorporate chemical amplification. These efforts were stimulated by the fact that the quantum yield of typical diazoquinones of the sort used in the formulation of positive photoresists is 0.2 to 0.3 thus, three or four photons are required to transform a single molecule of sensitizer. This places a fundamental limit on the photo-sensitivity of such systems. 

Ito, H. Willson, G., "Chemical Amplification in the Design of Dry Developing Resist Materials," SPE Regional Technical Conference, Ellenville, New York, Nov. 1982. 

Methods 1 and 3 have been utilized in dry developed resist systems. To our knowledge, there are no resist systems commercially available that depend on post-exposure treatment other than the post-curing effect in negative electron beam resists mentioned earlier. Since such systems are still largely in the research phase we will not discuss them here but rather refer the reader to the literature for more detailed descriptions (44-50). 

Although other resist systems have been described in the literature, it does not appear that these newer resist formulations will displace the older more established resists for conventional wavelengths. Much more interest is being shown in dry-developable photoresists which will be discussed later. 

The simplest dry-developing scheme is that provided by the self-developing resists. The first example of this was reported by Bowden et al. 

A different approach has been used by Tsuda, Nakane and their collaborators (138,139) who showed that mixtures of poly(methylisopropenyl ketone) (PMIPK) containing a bisazide sensitizer such as 4,4 -diazodiphenyl sulfide or 4-methyl-2,6-di(4-azidobenzylidene) cyclohexanone function as negative dry-developable resists. It is claimed that the bisazide... 

Dry developers suitable for use in image forming devices are roughly classified into (53) ... 

Both methods have advantages and limitations. The latter approach allows dry development, for example with ammonia vapour, but there also exists the possibility of premature, indiscriminate coupling. The one-component system does not suffer from this instability, but its processing is a wet operation, which itself leads to instability of the final image. 

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