MLC capacitors for demanding applications; and completely non-magnetic parts

November 18, 2014 // By Graham Prophet
Syfer Technology, part of Knowles Capacitors, has a range of cost-effective MLC capacitors for a variety of designs, including demanding applications. The company has also applied its specialist expertise to producing totally non-magnetic trimmers – and also fixing hardware – for MRI scanners.

The PSL range of MLCCs is manufactured using Syfer's screen printing process and is suitable for power supplies, DC-DC converters, LED lighting, and other demanding applications. Features include C0G and X7R dielectric options; a capacitance range from 220 pF to 1.5 µF, temperature range up to 125ºC, rated voltages of 50V to 2 kV and full compliance with the RoHS and WEEE directives and lead-free solders.

Where high capacitance and high voltage is required, the PSL range can offer a cost effective solution for a variety of applications, in case sizes from 0805 to 2220. Manufactured in higher volumes to optimise production efficiencies, these standard components offer an economic solution for reasonable MOQs (minimum order quantities). The PSL range is also qualified to AEC-Q200 to meet demands from the automotive and other industries.

Whilst MLCCs are one of the most reliable components for surface mount applications, they can be vulnerable to cracks when affected by PCB movement, most often during the PCB assembly process. The resulting damage may not manifest itself immediately but could lead to field failure. Syfer’s FlexiCap polymer termination is selectable across the whole PSL range and allows for more 'bend’ and flexibility in board design.

Under its Voltronic brand, the company also supplies trimmer capacitors that are aimed primarily at the magnetic resonance imaging market (MRI “scanners”). As is well known, these instruments employ intense magnetic fields and all components must be completely non-magnetic.

The Voltronic trimmers employ sapphire as the ceramic element with pure brass for the metal components. The trimmers are 16.25-mm long (at minimum capacitance) and have a 2 kV working voltage, spanning 1 to 12 pF, with minimum Q of 3000 at 100 MHz.

Voltronic has found that it had to source pure “virgin” brass – that is, made from known-pure copper and zinc. “Commercial” brass, the company says, frequently contains a proportion of re-melted scrap and may be contaminated with metals