Issue link: https://iconnect007.uberflip.com/i/1381013
JUNE 2021 I DESIGN007 MAGAZINE 77 are Ohmega Technologies LLC. and Ticer Technologies. [1] Materials provided for resistor formation from Ohmega Technologies are described as a subtractive technology where the base mate- rial preparation begins with a thin-film resist- coated copper foil laminated onto a glass-rein- forced dielectric. In preparation, the company first electrodeposits a thin coating of nickel phosphorous (NiP) alloy onto the copper foil's matte or tooth side. Base resist values of the Ohmega coated copper foils range from 10 Ω/ sq. to 377 Ω/sq. (Table 1). e power dissipation is the rate at which resist energy is lost in elements. e power capability for embedded resistors will depend on the physical size of the resistor elements, temperature rating of the surrounding substrate materials, and the board stackup. In the end it boils down to how the heat generated is man- aged. Typical power dissipation for most thin- film resistor designs operating at an ambient of less than 70 °C is approximately 1/10 to 1/8 watt. Coated foil materials can be furnished as a foil only product or pre-laminated to a variety of standard FR-4, polyimide, or more special- ized microwave substrate materials. e pre- laminated material can be furnished directly from Ohmega Technologies as well as other sources, including Arlon, Rogers, and Taconic. e company also offers a NiP material with a sheet resistivity of 377 ohms per square, which was developed for a range of specialized appli- cations that include high impedance and fre- quency selective surfaces, antenna arrays, or as radar absorbing materials for resistive cards. ree variations of resistive-coated thin- film on copper foils are available from Ticer Technologies that provide a specific range of resist coatings: nickel-chromium (NiCr), nickel chromium-aluminum-silicon (NCAS) and chromium-silicon-monoxide (CrSiO). Individually, these alloy compositions can fur- nish a broad range of base resist values from 25 ohms to 1K ohms. Table 2 details the sheet resistance value range, tolerance and the maxi- mum power dissipation factor for the three resistance alloy compositions noted. Ticer Technologies resistive-coated copper foil material is furnished in sheet form or as a product pre-laminated onto standard ROHS- compliant FR-4 glass-reinforced resin material Table 1: Ohmega Technologies resistive sheet materials.