T H E P H O T O - M A S K G U I D E JD Photo-Tools Page 41 of 91 Dimensional Stability Environmental and mechanical conditions can affect the overall size of the mask – considerably where polyester film is concerned, and to a lesser degree where Glass is...
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T H E P H O T O - M A S K G U I D E JD Photo-Tools Page 41 of 91 Dimensional Stability Environmental and mechanical conditions can affect the overall size of the mask – considerably where polyester film is concerned, and to a lesser degree where Glass is concerned. The dimensions of a film photo-mask will change under the influence of 4 factors; changes in temperature, changes in humidity, mechanical tensions and ageing. Some dimensional changes are reversible, whereas others are not. The dimensions of a Glass photo-mask will only change with two of these factors; temperature and mechanical tensions, so movement due to humidity is avoided. Because humidity is probably the hardest of these 4 factors to control adequately – and also has the biggest influence on dimensional changes – Glass photo- masks would always be the recommended product if you need to control the accuracy of the mask to critical dimensions. Film is made up of a polyester base with a thin layer of gelatine on its surf
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