The Challenge of Heat

In modern electronics, particularly in Electric Vehicles (EVs) and down-hole drilling equipment, components are subjected to extreme thermal stress. Standard electromechanical relays typically operate safely only up to 85°C. Beyond this limit, several failure modes occur:

• Plastic Deformation: The relay housing can warp, causing mechanical jamming.
• Outgassing: Volatile compounds from the coil insulation release gases that contaminate contacts.
• Contact Oxidation: Increased temperatures accelerate the formation of oxide layers, increasing resistance.

The Solution: Hermetic Sealing & Material Science

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To solve these issues, the MSG Series utilizes a specialized construction designed specifically for the -40°C to +155°C range[cite: 39, 86].

1. Hermetic Glass Seal

Unlike plastic-sealed relays, the reed switch contacts in the MSG series are encapsulated in a glass tube filled with inert gas (Nitrogen/Hydrogen). [cite_start]This ensures that even at 155°C, the contacts are never exposed to oxygen, completely preventing oxidation and maintaining a low contact resistance of 150 mΩ max[cite: 39, 86].

2. Thermal Stability

The coil assembly uses high-grade copper wire and potting compounds formulated to resist thermal expansion stresses. [cite_start]This allows the relay to maintain a stable Pull-in Voltage (3.8V for 5V coils) [cite: 86] even when the ambient temperature rises, ensuring consistent switching logic.

Typical Applications

This high-temperature capability makes the MSG series ideal for:

• Automotive ECUs: Engine control units mounted near the engine block.
• Oil & Gas: Sensors used in deep-bore drilling where geothermal heat is a factor.
• Industrial Ovens: Control boards situated near heating elements.

Conclusion

When designing for harsh environments, “standard” is not enough. Utilizing a specialized high-temperature Reed Relay like the MSG Series eliminates the most common causes of field failure, ensuring your system passes the most rigorous qualification tests.