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Filters survive high temp processes

Posted: 13 Jul 2005 ?? ?Print Version ?Bookmark and Share

Keywords:syfer technology? emi filter? sfsr? sfst? sfsu?

Syfer Technology Ltd. offers a wide range of solder-mount feedthrough EMI filters that are fully compliant to the European Union's Restriction of Hazardous Substances (RoHS) Directive and will withstand the higher soldering temperatures of lead-replacement materials.

The new solder-mount SFSR, SFST and SFSU EMI filters target high reliability, high performance applications that require a rugged design, whereby the filter is mounted on the panel or equipment chassis. The filters incorporate high reliability multilayer discoidal capacitors based on high stability C0G and X7R ceramic dielectrics. With a rated voltage of 500V and a current rating of 10A, the devices are qualified across the operating temperature range of -55C to 125C.

The fully epoxy-sealed devices are available in three body sizes. The SFSR EMI filters feature a body diameter of 2.8mm, and offer a capacitance range from 10pF to 220pF for C0G and 470pF to 10nF for X7R. The SFST devices have a 3.25mm body diameter, with capacitance values from 10pF to 150pF for C0G and 220pF to 33nF for X7R. The SFSU devices provide a capacitance value range from 10pF to 150pF for C0G and 220pF to 470nF for X7R with a body diameter of 5.6mm.

A critical feature of leaded devices such as these is that the internal solder must have a higher melting point than the solder used between the filter and the external panel to which it is subsequently connected, explained the company. If not, there is a significant risk that the internal solder will reflow and potentially lead to a device failure. Today, typical lead-free solders such as SAC types that are comprised of tin/silver/copper have a melting point of 260C, significantly higher than the traditional 60/40 tin/lead solder melting point of 220C. To avoid any potential problems, the SFSR, SFST and SFSU devices use an internal solder type with a melting point sufficiently higher than 260C, thus are specified to withstand lead-free soldering process temperatures, said the company.

Applications include industrial telecommunications equipment and microwave modules as well as systems for the aerospace and defense sectors.

Prices for the EMI filters range between $1.60 to $5.50, depending on capacitance value, voltage and quantity.

- Gina Roos


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