Executive Summary

In high-voltage power detection, medical imaging equipment (X-Ray/CT), and high-energy physics instruments, Flat Style / SIP high-voltage thick film resistors are considered the "heart" components of systems due to their high voltage withstand density and excellent long-term stability. For a long time, Japan's KOA company's RK92 series defined the industrial standard in this field with its standardized design.

However, with the global reconstruction of the passive component supply chain, and Japanese manufacturers shifting production capacity towards automotive-grade SMD components, the KOA RK92 series has officially entered the End of Life (EOL) stage. Facing the severe situation where the original manufacturer no longer accepts new orders and market inventory is depleted, engineers urgently need to find a replacement that can achieve Pin-to-Pin compatibility and ensure long-term supply.

Leveraging its deep expertise in high-voltage insulation materials, HVC Company has launched the HVRGXP series, specifically designed to fill this market gap. Unlike simple low-end imitations on the market, the HVRGXP series adopts serpentine non-inductive printing technology and a 96% high-purity alumina substrate. It not only perfectly replicates the physical dimensions of the RK92 but also achieves an "expert-grade" performance leap in high-frequency pulse response, Voltage Coefficient of Resistance (VCR), and non-standard customization flexibility.

At-a-glance benchmark: KOA RK92 vs HVC HVRGXP

1. Background: Supply Chain Crisis and Opportunities Behind RK92 EOL

The discontinuation of KOA RK92 is not an isolated incident but a microcosm of the shrinking market for traditional Through-Hole high-voltage resistors.

1.1 The Pain of 'Supply Disruption' in the Existing Market

For many long-lifecycle industrial and medical devices, the EOL of RK92 is critical. The motherboard designs for these devices were finalized 5-10 years ago, with extremely compact PCB layouts and stringent safety certifications, making it difficult to easily switch to SMD resistors or change mounting hole pitches. Generic resistors on the market often have mismatched pin spacing or insufficient voltage margin, leading to soaring maintenance costs.

1.2 HVC's 'Technological Down-Scaling' Strategy

As a leading global manufacturer of high-voltage components, HVC's core business covers ultra-high voltage capacitors of 100kV+. For HVC, producing SIP resistors below 30kV is a typical case of "technological downward compatibility." We leverage our experience in ultra-high voltage insulation, vacuum encapsulation, and special ceramic sintering to redefine the manufacturing standards for SIP high-voltage resistors. HVC not only promises Long-term Availability but also compresses the lead time from the original manufacturer's 20 weeks to 4-6 weeks, providing a supply chain safety anchor for global customers.

2. In-depth Technical Analysis: Evolution from 'General-Purpose' to 'Expert-Grade'

KOA RK92 is an excellent general-purpose resistor, but its generic design gradually revealed bottlenecks when facing modern high-voltage equipment (such as high-frequency pulse power supplies, precision voltage dividers). The HVC HVRGXP series has undergone professional upgrades in the following three core dimensions:

2.1 Substrate Material: The Thermal Revolution of 96% Alumina

Ordinary thick film resistors often use 85% or 90% purity alumina substrates, which have average thermal conductivity. * HVC Expert-Grade Process: The HVRGXP series comes standard with a 96% high-purity alumina (Al₂O₃) substrate. * Technical Value: High-purity substrates have 30% higher thermal conductivity than ordinary substrates. Under high-voltage loads, this means lower hot spot temperatures on the resistor surface, thereby significantly reducing the drift of the Temperature Coefficient of Resistance (TCR) and ensuring more stable resistance values during 7×24 hour continuous operation.

2.2 Circuit Design: Non-Inductive Serpentine Printing

Under nanosecond-level high-voltage pulses, the parasitic inductance of ordinary resistors can cause waveform oscillation or overshoot. * HVC Expert-Grade Process: We employ a unique computer-optimized serpentine non-inductive printing technology. By precisely calculating the mutual inductance cancellation of current paths, parasitic inductance is reduced to the microhenry (µH) level. * Application Scenarios: This makes HVRGXP highly suitable for high-frequency switching power supply feedback loops and pulse modulators, where it maintains pure resistive characteristics at high frequencies, avoiding interference from inductive components on the control loop.

2.3 Film Formulation: Extremely Low Voltage Coefficient (Low VCR)

A hidden killer for high-voltage resistors is the Voltage Coefficient of Resistance (VCR) – the phenomenon where resistance decreases as voltage increases. * HVC Expert-Grade Process: The HVRGXP series selects high-grade Ruthenium Oxide paste and optimizes the microscopic topological structure of conductive particles, controlling VCR to an extremely low level of < 2-5 ppm/V. * Practical Significance: For 10kV-level high-voltage dividers, this means that the voltage division ratio can maintain high consistency whether in low-voltage calibration or high-voltage operation, ensuring the absolute precision of sampled data.

3. Precise Comparison: KOA RK92 vs HVC HVRGXP Model Cross-Reference

To achieve Pin-to-Pin lossless replacement, HVC has strictly modeled the HVRGXP series 1:1 according to the physical dimensions and power ratings of KOA RK92. The following cross-reference table is compiled based on actual datasheets, covering a full range of replacement solutions from compact to high-power types.

3.1 Practical Cross-Reference Table for Common Models

> Note: The HVRGXP suffix (e.g., 7.26, 5.10) represents the physical dimension code of the substrate, ensuring the mounting hole pitch is identical to the original KOA part.

4. Why Choose HVC? Value Beyond 'Replacement'

When facing the discontinuation of KOA RK92, choosing the HVC HVRGXP series is not just about solving an immediate problem, but also a strategic upgrade of the supply chain.

4.1 Customization Services: A Game-Changing Advantage

Before its discontinuation, KOA only offered standard E24 series resistance values, often requiring huge Minimum Order Quantities (MOQ) for non-standard values (such as 123MΩ or 4.56GΩ). * HVC Advantage: Relying on its in-house thick film printing line and laser trimming technology, HVC has turned "customization" into a "standard service." We can produce resistors of any resistance value and any tolerance for you, with extremely low MOQs, flexibly meeting the maintenance needs of old equipment and new R&D requirements.

4.2 Robust Assurance of Insulation Reliability

HVC leverages its experience in manufacturing ultra-high voltage capacitors to introduce epoxy vacuum encapsulation (Conformal Coating) technology into resistor manufacturing. * HVC Advantage: The encapsulation layer of the HVRGXP series is dense and bubble-free, having passed stringent Double 85 tests (85℃/85%RH). Even in outdoor high-humidity environments or high-altitude regions, it maintains excellent insulation performance, preventing surface flashover, which is unmatched by ordinary dip coating processes.

5. Conclusion: From Passive to Proactive

The discontinuation of KOA RK92 is a foregone conclusion. Continuing to search for backlog inventory is not only costly but also carries quality risks such as pin oxidation and poor solderability.

By choosing the HVC HVRGXP series, you gain not just a resistor of the same size, but a long-term stable supply commitment and expert-grade technical support.

Facing the EOL crisis, HVC is your most reliable "Plan B" and "ultimate solution."

Initiate Replacement Verification Immediately

Please send us your specific KOA RK92 model, and HVC's senior engineers will provide you with a Pin-to-Pin cross-reference solution and free samples within 24 hours.

• Global Sales & Technical Consulting: sales@hv-caps.com
• HVC High Voltage Resistor Product Center: https://www.hv-caps.com/products/High-Voltage-resistor-Flat-Style.html

Copyright © 2026 HVC Company. KOA and RK92 mentioned herein are registered trademarks of their respective holders, and this article is for technical compatibility and replacement selection explanation only.