Engineering Alternative Solution for Caddock High Voltage Resistors

Abstract

This document elaborates on the technical architecture of HVC (High Voltage Components) high voltage resistors and provides an in-depth performance comparison analysis with Caddock Electronics' mainstream product lines. For demanding high voltage application scenarios such as medical imaging, industrial precision testing, and scientific research instruments, HVC achieves fully equivalent electrical performance and physical compatibility with Caddock TF/TG/MG series through its proprietary ruthenium-based thick film process, offering global engineers a highly reliable, short-lead-time alternative.

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1. Technical Background and Design Challenges

In the design of high voltage electronic systems, resistors are constantly subjected to extreme electric field stress and must overcome the following three major physical challenges:

• Voltage Coefficient of Resistance (VCR): Under high electric fields, the tunneling effect between conductive particles intensifies, leading to a non-linear drift in resistance (resistance decreases as voltage increases).
• Parasitic Inductance: Traditional wire-wound or helical cut processes can introduce inductance, severely affecting nanosecond-level pulse response and high-frequency signal integrity.
• Thermal Stability: Thermal stress caused by high power dissipation can lead to micro-cracks in the substrate or permanent resistance drift.

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2. HVC Core Technical Specifications Benchmark

The table below shows the benchmarking of HVC high voltage resistors against Caddock products on key parameters. The data indicates that HVC has achieved equivalent or even superior levels in core specifications.

Key Parameter	HVC Specification (Typical)	Caddock Reference Series	Performance Assessment
Resistance Tolerance	±0.1% ~ ±1%	TF Series (±0.1%)	Fully equivalent, meets precision voltage divider requirements
Temperature Coefficient (TCR)	±25 ppm/°C	TF Series (±25 ppm/°C)	Fully equivalent, excellent low-drift characteristics
Voltage Coefficient (VCR)	< 0.5 ppm/V	TG Series (< 10 ppm/V)	HVC offers superior linearity, more stable under high voltage
Parasitic Inductance	< 0.08 μH	MG Series (non-inductive design)	Low-inductance design, suitable for high-frequency pulse applications

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3. Quick Selection Guide

0.5W - 1W Precision Instrument Grade

Caddock Model	Power	Voltage	Resistance Range	Size (mm)	HVC Model	Compatibility
MG650	0.5W	600V	200Ω-5MΩ	7.95×2.39	HVR-BOP-3.5×8-5M00-F-25-600	✅ Perfect Match
MG660	0.6W	1kV	400Ω-10MΩ	12.70×2.39	HVR-BOP-3.5×13-10M0-F-25-1k	✅ Perfect Match
MG680	0.8W	2kV	600Ω-20MΩ	19.05×2.39	HVR-BOP-3.5×19-20M0-F-25-2k	✅ Perfect Match
MG710	1.0W	4kV	800Ω-50MΩ	25.40×2.39	HVR-BOP-3.5×25-50M0-F-25-4k	✅ Perfect Match

1W - 3W Medium Power Supply Grade

Caddock Model	Power	Voltage	Resistance Range	Size (mm)	HVC Model	Compatibility
MG715	1.0W	2kV	400Ω-50MΩ	19.05×3.56	HVR-BSP-7×19-50M0-F-25-2k	✅ Perfect Match
MG720	2.0W	6kV	1kΩ-150MΩ	38.10×3.56	HVR-BSP-7×38-150M-F-25-6k	✅ Perfect Match
MG730	3.0W	6kV	500Ω-250MΩ	38.10×6.10	HVR-BSP-7×38-250M-F-25-6k-HD	✅ High Power Density

5W - 15W High Voltage Load Grade

Caddock Model	Power	Voltage	Resistance Range	Size (mm)	HVC Model	Compatibility
MG745	5.0W	15kV	1kΩ-500MΩ	76.20×6.10	HVR-BSP-7×76-500M-F-25-15k	✅ Performance Upgrade
MG810	10.0W	25kV	1kΩ-1.25GΩ	127.0×8.00	HVR-BSP-7×127-1G25-F-25-25k	✅ High Redundancy
MG815	15.0W	30kV	1kΩ-2GΩ	152.4×8.89	HVR-BSP-7×152-2G00-F-25-30k	✅ High Redundancy

4. HVC Part Number Coding Rules

HVR-[Series]-[Diameter x Length]-[Resistance]-[Tolerance]-[TCR]-[Voltage]

Code	Meaning	Example
HVR	High Voltage Resistor prefix	HVR-BSP-7×19
BSP/BOP	φ7mm/φ3.5mm ceramic rod	BSP-7×19, BOP-3.5×8
Resistance	5M00=5MΩ, 1G25=1.25GΩ	10M0, 500M
Tolerance	D=±0.5%, F=±1%, J=±5%	F
TCR	25=±25ppm/°C, 50=±50ppm/°C	25
Voltage	600=600V, 2k=2kV, 15k=15kV	6k

Ordering Example: Replace MG715-10M-1% → HVR-BSP-7×19-10M0-F-25-2k

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5. Typical Replacement Cases

Caddock P/N	HVC Model	Key Technical Upgrades
MG715-10M-1%	HVR-BSP-7×19-10M0-F-25-2k	1:1 size compatible, ±25ppm low TCR
MG720-100M-1%	HVR-BSP-7×38-100M-F-25-6k	Enhanced pulse withstand, suitable for X-ray machines
MG810-1G-1%	HVR-BSP-7×127-1G00-F-25-25k	Ultra-high resistance, research-grade stability

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6. Microstructure and Material Science

The high performance of HVC stems from fundamental innovation in thick film material science. We employ a unique ruthenium-based thick film paste (Ruthenium-based Paste) combined with multi-layer printing and high-temperature sintering processes:

• Grain Size Control: The conductive phase grain size is strictly controlled within 0.5-2μm, effectively dispersing the microscopic electric field and reducing the risk of partial discharge.
• Interface Energy Level Optimization: By optimizing the wettability between the glass phase and conductive phase, the Electromigration phenomenon under long-term high voltage is suppressed, extending device service life.
• Low-Inductance Pattern Design: Optimized serpentine (Serpentine) or planar non-inductive electrode patterns are employed, with measured parasitic inductance values < 0.08 μH, ensuring excellent frequency response.

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7. Cross Reference Guide

To facilitate rapid model selection for engineers, HVC has established a direct mapping relationship with the standard Caddock product lines:

Replacing Caddock TF Series → HVC Precision Series

• Typical Applications: High voltage precision voltage dividers, reference voltage sources, digital multimeters.
• Key Features: Ultra-low TCR, high precision, flat package.

Replacing Caddock TG Series → HVC High Voltage Stick

• Typical Applications: High voltage probes, static eliminators, specialty power supplies.
• Key Features: Ultra-high resistance values (up to 10GΩ+), excellent VCR characteristics.

Replacing Caddock MG/MX Series → HVC Power Film

• Typical Applications: X-ray tube power supplies, mass spectrometers, ion implanters.
• Key Features: High power density, axial leads, capable of withstanding high-energy pulses.

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8. Verification Test Data

Reliability is the core of any alternative solution. HVC laboratories have conducted rigorous verification in accordance with IEC 60115-8 standards:

• Test Conditions: Applied 10kV continuous DC voltage stress.
• Test Duration: 1000 hours of high-temperature load aging.
• Test Results: Resistance drift rate of HVC MG series samples ΔR < 0.5%, demonstrating excellent long-term stability.

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9. Engineering Recommendations

To ensure optimal system performance after replacement, the following design guidelines are recommended:

1. PCB Layout Compatibility: HVC products strictly adhere to industrial standard dimensions. Maintain the same pad spacing as the original Caddock design (refer to the appendix dimension table) to achieve in-place replacement.
2. Derating Design: To extend device service life, it is recommended to keep the continuous operating voltage within 70% of the rated voltage.
3. Thermal Management: When the power density of a single resistor exceeds 2W, adding forced air cooling or using thermally conductive potting materials is recommended to prevent local hot spot accumulation.

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Appendix: HVC MG Series (Replacing Caddock MG) Complete Specification Table

Note: Only common models are listed below. For the complete list, please refer to the datasheet.

HVC Model	Rated Power (W)	Max Working Voltage (kV)	Resistance Range	Size (mm)	Replaces Caddock
MG650	0.5	0.6	200Ω - 5MΩ	7.95 x 2.39	MG650
MG680	0.8	2.0	600Ω - 20MΩ	19.05 x 2.39	MG680
MG710	1.0	4.0	800Ω - 50MΩ	25.40 x 2.39	MG710
MG720	2.0	6.0	1kΩ - 150MΩ	38.10 x 3.56	MG720
MG735	3.6	10.0	750Ω - 300MΩ	50.80 x 6.10	MG735
MG745	5.0	15.0	1kΩ - 500MΩ	76.20 x 6.10	MG745
MG810	10.0	25.0	1kΩ - 1.25GΩ	127.0 x 8.00	MG810
MG815	15.0	30.0	1kΩ - 2GΩ	152.4 x 8.89	MG815

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Contact Us

HVC is dedicated to optimizing global supply chains through technological innovation. If you have any questions about the above alternative solutions, or need to apply for samples for verification, please feel free to contact us.

© HVC Components. Caddock® is a registered trademark of Caddock Electronics, Inc. This document is for technical comparison purposes only and does not imply any affiliation between HVC and that brand.