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X-rays, a new way to ensure the cleanliness of semiconductive compounds
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Borealis A/S
: 21 June, 2000 (New Product) |
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Borealis, the world's leading supplier of XLPE compounds for high voltage and extra high voltage cables, has developed a new technique for quality control of semiconductive compounds for demanding applications based on soft X-ray technique. It is well known that presence of foreign particles in the semiconductive layers can be a starting point for 'tree-formation' that can eventually grow to a size where the defect leads to a failure and breakdown of the cable. Inorganic grit particles in the size of 50-100Xm originating from the carbon black production process have been found to contain traces of Al, Si, Mg and Ca. These elements have also been found in the ion tracks of trees and have, therefore, been judged as critical for the long time performance of the cables. |
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Borealis, the world's leading supplier of XLPE compounds for high voltage and extra high voltage cables, has developed a new technique for quality control of semiconductive compounds for demanding applications based on soft X-ray technique.
It is well known that presence of foreign particles in the semiconductive layers can be a starting point for 'tree-formation' that can eventually grow to a size where the defect leads to a failure and breakdown of the cable. Inorganic grit particles in the size of 50-100Xm originating from the carbon black production process have been found to contain traces of Al, Si, Mg and Ca. These elements have also been found in the ion tracks of trees and have, therefore, been judged as critical for the long time performance of the cables.
Although the grit-level in commercial carbon black has dropped from 400 to only 10 ppm over the last twenty years, there is still a need to monitor and quantify the level present in current products.
Borealis has, therefore, developed a fully automatic, on-line test method. It involves analysing an extruded tape by a system involving soft X-ray. The special feature is that the wavelength can be adjusted to see the semicon tape as transparent while still with good accuracy detecting the relevant inorganic particles. The method has proven reliable and successful and will be progressively introduced as a standard method to ensure high product consistency and form a base for further improvements of the Borealis semiconductive products. |
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