The technical requirements for enamels, such as printing properteis, firing ranges, opacity, anti-stick properties and chemical durability used in the screen-printing of enamels and silverpastes for automotive glasses are described. Silverpastes are used for printing of hot-lines, antennas and sensors, whereas enamels are used as long time protection of the adhesive layers against UV-radiation. The compatibility to the black enamel print on backlights is very important. It is shown that the use of lead-free enamels based on bismuth or borosilicate frits is guaranted. The screen printing enamels typically consisted of an inorganic black stained frit powde and an organic vehicle (the medium) . Organic media are available for IR-drying and for UV-curing pastes. Major component of IR-media is a solvent (pine oil) and some resins which are removed by drying after the screen printing process. The resin is burned off during firing of the enamel. UV-pastes consisted of acrylic compounds. The firing curves in glass-bending furnaces for toughened and laminated glasses, segbended or pressbended, are shown and the firing ranges evaluated. The performance of standard and high loading printion-oil with lead-free enamel powders with regard to the viscosity and opacity is listed. Typical pasting ratios of leaded enamels with standard IR-oils are 100:25. The same ratios can be achieved with low density lead-free powders using high loading media as Cerdec's 80 10 10. The typical silverpastes consists of 50 weight-% to 80 weight-% silverpowder, 2 weight-% to 6 weight-% of low melting glass flux and an organic vehiclt to provide screen-printing properties. Cerdec's new developed lead-free silverpastes can be used to replace current lead-based products. Field tests with automotive backlights using new lead-free silverpastes showed that the glass crack rate could be significantly decreased and pull-off forces enhanced.
Screen-printing enamels and silverpastes for automotive glasses
Silberpasten und Email für Siebdruck auf Autoverglasungen
1997
3 Seiten, 4 Bilder, 2 Tabellen, 3 Quellen
Conference paper
English
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