Case Study: DuPont thick-film technology improves reliability of antilock brakes
Multilayer thick-film technology creates a high-density circuit small enough to fit into a hydraulic braking system.
Application Description
Delco Electronics needed to produce a high-density circuit small enough to fit into and be integral with a hydraulic braking system. Because automotive conditions are particularly harsh, Delco needed a circuit that could withstand extreme temperature variations, vibration and exposure to brake fluids, and that could mount directly on the master cylinder. Delco also wanted a circuit that could be manufactured cost-effectively in high-volume production.
Materials Selected and Why
The circuit's dielectric system comprises three print layers per dielectric level. The first layer is DuPont™ QM42, a filled crystallized glass dielectric that resists silver diffusion and migration and increases the reproducibility of the resistors. The second and third layers are DuPont™ 5707H, a filled-glass dielectric with wide conductor compatibility and good mechanical strength.
Conductors inside DuPont™ 7484F, a 3:1 silver-palladium conductor, and DuPont™ QS179, a silver-platinum conductor. Both conductor compositions achieve 125 µm lines and spaces in long print run.
DuPont's 1900 series resistors also are used on the circuits. The resistors with a TCR of ±100ppm, are laser-trimmable and exhibit less than 1% change in resistance following laser trimming, without encapsulation.
Benefits Gained
The thick-film technology used in the circuits helped the modules pass tests in vibration, brake fluid exposure, ice-water immersion, water jet spray, electrostatic discharge, electromagnetic susceptibility and radiation, and biased humidity, thermal shock, and temperature cycling.
The modules are cost-effectively manufactured in high volume.
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