Product Overview

This document details the specifications and features of the RK73 series of thick film flat chip resistors with anti-sulfuration properties, including models RK73B, RK73H, and RK73Z-RT. These resistors are designed for high reliability in harsh environments such as automotive, medical, and aerospace applications.

Specifications and Construction

• Structure: The resistors consist of a ceramic substrate, resistive metal glaze thick film, inner electrodes with a triple-layer structure, nickel plating, solder plating, and a protective coating.
• Coating Colors: Black (RK73B, RK73Z variants), Blue (RK73H), Green (RK73Z1E).
• Dimensions: Various sizes from 0402 (1.0 x 0.5 mm) up to 2512 (6.3 x 3.1 mm) with corresponding weights provided.

Key Features

• Excellent anti-sulfuration due to high sulfuration-proof inner top electrode material preventing sulfide-induced open circuits.
• Metal glaze thick film ensures superior heat and weather resistance.
• Triple-layer electrode structure provides high stability and reliability.
• Compatible with both flow and reflow soldering processes.
• Compliant with EU RoHS regulations; Pb-glass in electrodes and resistive elements is exempted.
• AEC-Q200 qualification data available, supporting automotive-grade reliability.

Applications

Suitable for car electronics, power supplies, industrial robots, and other equipment requiring high reliability under harsh conditions.

Derating and Operating Conditions

For ambient temperatures above 70°C, power or current ratings must be derated according to the provided derating curve to prevent damage. The rated voltage is the lower of (power rating × resistance) or the maximum working voltage.

Ratings and Electrical Characteristics

• Power Ratings: Range from 0.063W (0402 size) up to 1W (2512 size).
• Resistance Range: From 1Ω to 10MΩ depending on type and tolerance.
• Resistance Tolerance: ±0.5%, ±1%, ±2%, ±5% options.
• Temperature Coefficient of Resistance (T.C.R.): Typically ±200 ppm/K.
• Maximum Working Voltages: Vary by size, e.g., 50V for 0402, up to 200V for 1206 and larger.
• Maximum Overload Voltages: Typically 2 to 4 times the rated voltage for short durations.

Performance and Reliability Tests

• Resistance stability within specified tolerance.
• Overload test: Rated voltage multiplied by 2 to 2.5 applied for 5 seconds.
• Solder heat resistance: 260°C for 10 seconds.
• Rapid temperature change: 100 cycles between -55°C and +125°C.
• Moisture resistance: 1000 hours at 40°C, 90-95% RH with ON/OFF cycling.
• Endurance at 70°C: 1000 hours with ON/OFF cycling.
• High temperature exposure: 1000 hours at 155°C.
• Sulfuration test: Exposure to 1000 ppm H2S at 25°C, 90% RH for 720 hours with minimal resistance change.

Precautions for Use

The alumina substrate has a different thermal expansion coefficient than typical mounting boards, which can cause solder joint cracks under repeated thermal cycling or load ON/OFF cycles, especially for larger sizes (W2H, W3A). Design considerations should include pad size, solder volume, and board heat dissipation to mitigate crack risks.

Packaging and Ordering Information

• Available in tape and reel packaging with various pitch options (2mm, 4mm) and bulk packaging.
• Packaging quantities vary by size and type, typically ranging from 4,000 to 20,000 pieces per reel.

Standards Compliance

• IEC 60115-8
• JIS C 5201-8
• EIAJ RC-2134C

Important Notes

Specifications are subject to change without notice. Users must confirm technical specifications before ordering or use. Consultation is mandatory before using these resistors in life-critical or high-risk applications such as automotive, medical, or aerospace equipment due to potential risks of malfunction or failure.