SBR seat belt reminder sensors: film printing and validation

In brief

SBR means seat belt reminder. A film-based occupancy sensor can provide the occupied-seat input. Printing equipment makes part of the sensor, while system performance needs separate validation.

What is the role of the sensor in an SBR system?

IEE describes a foil-based pressure-sensitive sensor that detects a seated occupant and provides an input for a seat belt reminder. The complete SBR function also depends on wiring, controller logic and vehicle warnings. A printed film alone is not a complete SBR system.

Which layers can be printed?

A candidate film stack may place conductive traces, pressure-sensitive or contact features, and insulation on a substrate such as PET, followed by curing, lamination and die cutting. The actual stack depends on the sensing principle and customer drawing. Henkel lists silver and carbon inks for flexible substrates, including carbon materials for contacts and sensors. Ink supplier data does not qualify a particular LICHAO machine and formulation.

What matters in roll-to-roll printing?

Define film thickness, trace geometry, screen and ink system first. Then evaluate web tension, registration, drying temperature, cleanliness and downstream lamination. LICHAO equipment supports PET and flexible circuit boards for its reel-to-reel screen printer, with a 0.075–0.38 mm substrate range and 0.1 mm repeat registration figure. These are equipment specifications, subject to sample testing for the actual sensor.

How should samples be qualified?

Measure resistance or output in empty and occupied states, the trigger window across loads and seating positions, drift after repeated loading, and changes after humidity, bending, foam integration and harness assembly. The customer’s sensor and vehicle-level specification determines acceptance.

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