Surface-mount RTP device helps protect against thermal events damage

Tyco Electronics introduced has a technology that enables manufacturers to incorporate surface-mountable thermal protection in their standard RoHS-compliant reflow assembly process.

Tyco says its reflowable thermal protection (RTP) device may be easily installed using industry-standard pick-and-place and Pb-free reflow equipment. It is designed to withstand multiple reflow passes with peak temperatures exceeding 200°C and yet, in the field, will open when it detects temperatures above 200°C.

The first in this RTP product family, the RTP200R120SA (RTP200) device, helps fulfill the most stringent AECQ-based specification requirements for automotive electronics. The RTP200 device can also be used to replace redundant power FETs, relays and heavy heat sinks typically used in automotive designs, while also offering a robust solution for IT server, telecom power supply and other industrial applications. The RTP device helps protect against thermal-runaway damage caused by capacitors, ICs, resistors and other power components which can crack and fail, or from the effects of any type of corrosion-induced heating.

The RTP200 device offers a low 1.2mΩ (typical) series resistance, as well as high-current DC-interrupt ratings of 200A at 16VDC and 100A at 32VDC. This thermal protection device helps to meet reliability requirements of automotive power electronics systems, including ABS, cooling fan and power steering applications. The RTP200 device's 200°C open temperature assists in preventing false activations and enhances system reliability since it has a value above the normal operating window of most normally

functioning electronics, but below the melt-point of typical lead-free solders. As a result, the RTP200 device will not open if surrounding components are operating in their target temperature range, but it will open before a component de-solders and creates the potential risk of additional short circuits. To permit it to open at 200°C in the field, the RTP device utilizes a one-time electronic activation process to become thermally sensitive.

Tyco explains that the device's thermal sensitivity is beneficial since, in some cases, failed power components may not generate a dead short circuit overcurrent condition, but instead may create a resistive short that cannot be opened by a traditional fuse. This type of event may actually reduce load current, but can still result in unsafe thermal runaway conditions. The RTP200 device helps prevent damage caused by both dead short circuit and resistive short-circuit conditions.

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