Riedon’s non-magnetic resistors like our CBR series and CHR seriesare appropriate for medical applications such in the field of magnetic-resonance (MRI) and computer tomography (CT), where electronic circuits are located in high magnetic fields. The resistor contact areas do not contain Nickel, they are made of metal alloys based on PtAg and PtPdAg, and available as thick film pastes, which are applied by roller-coating or dipping processes onto the wrap-around areas of the chip components and fired in the range of 850ºC.
The standard SMD soldering processes can be used, but these resistors are also suited for contact processes using silver-based conductive epoxy. The contact-technique of conductive epoxy is used mainly in applications where soldering techniques cannot be applied by technical reasons like the usage of temperature-sensitive components which would be affected by high soldering temperatures, or the usage of unpackaged semiconductors on the same board.
Also, another advantage of our non-magnetic thick film chip resistors with PtAg or PtPdAg contacts is suitability for applications at higher temperatures than the typical maximum temperature of 155ºC. These resistors contain no organic material and no tin or tin-lead layers, and the firing temperatures for the resistive and conductive layers are in the temperature range of 850ºC. Due to these reasons such resistors will have no substantial change of their properties and stability all the way up to 300ºC.