Hermetically sealed and robustly constructed ceramic fuses
28 September 2018
Schurter extends its MGA/MGA-S line of 1206 dimension SMD ceramic fuses with an aviation version that is tin whisker free and dispenses with leaded coating.
Crystalline tin dendrites and tin whiskers pose a considerable risk of short circuits in highly dense electronics. Dendrites form during the electro-deposition process, whereby heavy marks could appear on the fuse end caps or housing. A thorough inspection and cleaning is required according to MIL-PRF 23419. Tin whiskers form after the electro-deposition process. The cause is not well understood, although adding lead to otherwise pure tin soldering is commonly used as a preventable measure.
However, lead has become an unwanted element according to many environmental initiatives, e.g. RoHS directives. For this reason, Schurter has extended the successful SMD thin-film fuse family MGA with the new –A variant. In addition to the classic MGA and the ESA-certified MGA-S space fuse, the aviation version, MGA-A, uses gold alternatively to lead. Gold plated end caps provide a surface where neither whiskers nor dendrites can form. This makes the new MGA-A a safe solution for use in not only highly sensitive electronics in the aviation industry but often suffices for use in the industrial grade space sector.
The technical design is similar to that of the ESA-certified MGA-S. This means: hermetically sealed, ultra-robust construction, which is ideally suited for use in intrinsically safe applications according to ATEX and IECEx requirements. Despite its very small footprint (1206), the MGA-A has a particularly high breaking capacity of up to 300 A at 125 VDC and can be used in a wide temperature range of -55 to +125°C.
The new MGA-A from Schurter is suitable for all applications where the highest demands are placed on reliability and availability.
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