VPG Foil Resistors technology is based on proprietary NiCr alloy foil glued to ceramic substrate. Our strength is in the knowhow and ability of controlling and managing the physical differences and mechanical properties that exist, such as Thermal Coefficient of Expansion (TCE) and thickness. The unique construction of these two base components glued together enables to manage the balance of the internal stresses. This concludes an excellent performance of the Resistors.
Z1 is the state of the art of Foil technology that provides the ultimate performance for a variety of Ultra Precision Foil Resistors product families.
The Z1 technology combines two main components:
- • VPG proprietary (space grade) Z Foil with the outstanding Temperature Coefficient of Resistance (TCR), ±0.2 ppm/°C (parts per million per degree centigrade) typical.
- • VPG proprietary Polyimide based adhesive, providing additional advantages:
- • Superior strength of adhesion.
- • Improved heat conducting.
- • Withstanding high temperatures (300°C and above)
- • Very low sensitivity to moisture and humidity.
- • Long-term stability.
The performance and capabilities of a specific product will depend on the constituencies constructing the individual resistor. Today the market offers, some components that may induce specific limitations affecting the overall performance.
This article will demonstrate the advantages of some leading product families utilizing Z1 technology for applications that require stability, reliability and accuracy with our VPG Ultra Precision Foil Resistors.
VPG Foil Resistors Based on Z1 Foil Technology
The Z1 Foil, used in VPG Foil Resistors’ SMD resistor types, is a solid alloy 2 to 5 microns thick, is inherently stable (remarkably improved load life stability of 25 ppm), noise-free, and withstands ESD to 25kV or more. The alloy is bonded to the substrate and forms a single entity with balanced temperature characteristics for an unusually low and predictable TCR over a wide range from -55°C to more than 300°C. Due to the polyimide-based adhesive, VPG Z1 technology provides improved heat conductivity, very low sensitivity to moisture and humidity and outstanding long-term stability.
FRSM
FRSM is the most popular Z1 technology Surface mount chip resistor with a wide range of applications. FRSM is available with SnPb or Lead free terminals. The ultra-high precision FRSM is based on Z1 Foil Technology resistor elements by VPG Foil Resistors, which makes these resistors virtually insensitive to destabilizing factors. Due to Z1 foil Technology, FRSM Load Life Stability is extremely low 0.005% (50ppm), which means that this foil resistor will remain very stable for a very long time under working conditions. FRSM foil resistors are best suited for various high-precision applications, such as; Avionics, Military and Space (AMS), Automatic Test Equipment (ATE), precision instruments, cryogenics, test and measurement, medical, precision weighing, etc.
FRSG
The FRSG series wraparound surface mount chip resistors with Gold-plated terminals are excellent for high temperatures up to +300°C. The Gold plated terminals enable the use of special soldering materials designed for high temperatures. The FRSG series incorporates Z1 Foil Technology to extend its critical performance features to extremely high temperature environments, while maintaining the same low TCR. The FRSG’s working power at +200°C is 300mW and the rated power at +70°C is 750mW. The gold-plated terminals support the implementation of popular mounting methods used in the industry, therefore, facilitating any design considerations required. Drilling down-hole and deep space are high temperature applications where the FRSG is frequently used.
FRSH
The FRSH series wraparound surface mount chip resistors have extended soldering pads providing better heat dissipation and has a special Lead containing alloy terminals allowing for high temperatures up to + 225°C (working power: to 330mW at +220°C and rated power of 1.2W at +70°C). Its long-term stability is ±0.05% at +225°C for 2000 h, no power, and load life stability of ±0.05% typical at +200°C for 2000 h (working power). The FRSH resistor is suitable for high power/high temperature applications.
FRST
The FRST series has a full wraparound termination, and was designed especially for applications up to +200°C. Thanks to the Z1 Foil Technology, the FRST is very stable, less than 0.02% ΔR after 2000 h, derated power of 158mW at +175°C and load life stability of ±0.005% typical at 70°C (2000 h, rated power). Also FRST Moisture Resistance and Humidity (tested at 85°C/85% RH, 1000 hours) are as low as 100ppm ΔR Max. FRST is an excellent option for high stability electronic products and for applications involving high moisture and humidity environments.
HTHA & HTHG
HTHA & HTHG are chip resistors for hybrid circuits based on the Z1 Foil Technology. These new types of hybrid chips were designed especially for high temperature applications up to +240°C (working power: to 150mW at +220°C), and include gold plated terminals. HTHA is constructed for aluminum wire bonding applications, and HTHG is constructed for gold wire bonding applications. Both the HTHA & HTHG have excellent long term stability of 0.005% (50ppm) at +240°C for 2000h (no power) and Load Life stability of 0.005% (50ppm) at +220°C for 2000 h, at working power. These chip resistors are excellent for high precision at high temperatures applications.
CSM2512F & CSM3637F
Models CSM2512F & CSM3637F are SMT current sense resistors designed with 4 terminals for Kelvin connection. The unique combination of Z1 Foil Technology along with the designated 4 terminals Kelvin connection lead frame configuration results in a significant reduction in the component’s sensitivity to applied power changes such as Power Coefficient of Resistance (PCR) and thermal resistance.
CSM2512F & CSM3637F can support the tightest TCR of ±5 ppm/°C at a temperature range of -55°C to +125°C, 25°C Ref., with outstanding load life stability of 0.005% (50ppm) typical (70°C, 2000 h at rated power).
CSM2512F & CSM3637F resistors are suitable for applications such as, switching and linear power supplies, precision current-sensing, power management systems, power amplifiers, test and measurement equipment, etc.
The below performance table, provides a comparison between the Z1 Foil Technology and Z Foil Technology.
| Performances | Z Foil Technology | Z1 Foil Technology | |||
| Test or Conditions | MIL-PRF-55342 Characteristic ΔR Limits | Typical ΔR Limits | Performance ΔR Limits(1) | Typical ΔR Limits | Performance Δ R Limits(1) |
|
Thermal Shock, 100x (-65°C to +150°C) |
±0.1% |
±0.005% (50 ppm) |
±0.01% (100 ppm) |
±0.005% (50 ppm) |
±0.01% (100 ppm) |
|
Low Temperature Operation, -65°C, 45 min at Pnom |
±0.1% |
±0.005% (50 ppm) |
±0.01% (100 ppm) |
±0.0025% (25 ppm) |
±0.005% (50 ppm) |
| Short Time Overload, 6.25xRated Power, 5s | ±0.1% |
±0.005% (50 ppm) |
±0.01% (100 ppm) |
±0.005% (50 ppm) |
±0.01% (100 ppm) |
|
High Temperature Exposure, +150°C, 100h |
±0.1% |
±0.01% (100 ppm) |
±0.02% (200 ppm) |
±0.0025% (25 ppm) |
±0.005% (50 ppm) |
| Resistance to Soldering Heat | ±0.2% |
±0.005% (50 ppm) |
±0.01% (100 ppm) |
±0.005% (50 ppm) |
±0.01% (100 ppm) |
| Moisture Resistance | ±0.2% |
±0.005% (50 ppm) |
±0.02% (200 ppm) |
±0.003% (30 ppm) |
±0.01% (100 ppm) |
|
Humidity Test 85°C/85% RH, 1000 h |
±0.2% |
|
|
±0.005% (50 ppm) |
±0.01% (100 ppm) |
| Load Life Stability +70°C for 2000 h at Rated Power | ±0.5% |
±0.005% (50 ppm) |
±0.01% (100 ppm) |
±0.0025% (25 ppm) |
±0.005% (50 ppm) |
(1)As shown +0.01Ω to allow for measurement errors at low values
From this table one can see the Z1 Foil Technology has far superior performance in low temperature operation, high temperature exposure, moisture resistance, and load life stability. Z1 technology-based resistors provide the ultimate performance for ultra-precision foil resistors product families.