Case Study: Thick Film Provides Extreme Performance for Fan Speed Control Module
DuPont 6800 Series thick film resistor compositions provide a cost effective solution for a harsh-environment application.
Application Description
Thick film materials are often used in performance-driven military, aerospace, and telecommunications circuits, but they also provide value in high-volume applications where performance and cost are important criteria. This is the case with an automotive fan speed control module manufactured by Neohm Components of Turin, Italy, a large European supplier of automotive resistive components.
Neohm has been in business for more than 20 years and has been a regular user of thick film technology. The company’s thick-film automotive fan speed control module is normally fabricated using a discrete bulk resistor.
Neohm needed to create a robust materials solution for cost-effective volume manufacture, and also able to withstand the load and range of ambient conditions encountered in the fan speed control module application. The fan speed control unit incorporates a fuse, which provides protection if the fan becomes blocked and/or if the temperature rises beyond a critical level.
Materials Selected and Why
The Neohm fan speed control module resistor circuit uses DuPont 6800 Series thick film resistor compositions, 6160 Ag conductor, and QS580 glass encapsulant. The resistors are laser-trimmed to precise values corresponding to varied fan speeds.
By mounting the high-thermal-conductivity alumina ceramic substrate directly to an aluminum heat sink, the speed control module provides 75 watts of heat dissipation during operation, and up to 180 watts in the extreme case of a motor failure or blocked fan.
The modular nature of the thick film hybrid allows for bench testing to guarantee performance and reliability in operation.
