Precision that Connects.
For Over 90 Years.

A wire is a single conductor typically produced through a drawing process. A litz wire consists of multiple fine single strands twisted (stranded) together. This construction makes it significantly more flexible and resilient against mechanical stress and vibrations.

Enamelled litz wires consist of many strands that are individually insulated with enamel. This individual insulation keeps the strands electrically separated, which mitigates high-frequency effects and enables compact windings. Conventional copper litz wires, by contrast, usually only have an outer overall insulation; their individual strands are bare and in direct contact. While flexible, they are less suitable for high frequencies or precision windings because skin and proximity effects are much more pronounced.

The skin effect describes the tendency of alternating current (AC) to flow primarily on the surface of a conductor as frequency increases. This reduces the effective cross-section, increases electrical resistance, and leads to power losses.

In litz wire development, the skin effect is specifically addressed: multiple fine, individually insulated strands increase the total effective conductor surface area, thereby reducing losses at high frequencies. This is a primary reason why HF litz wires like RUPALIT® are significantly more efficient than solid conductors or standard litz wires.

The proximity effect describes how the current distribution in a conductor is influenced by adjacent AC-carrying conductors. The magnetic fields from neighboring conductors displace the current into specific regions of the cross-section – typically toward the outer edges. This increases local resistance and creates additional losses.

We specifically account for this effect when developing HF litz wires: through finely stranded, individually insulated wires, the current is distributed more homogeneously, and the interactions between parallel conductors are significantly reduced. This results in lower losses and more stable electrical properties – especially in windings, transformers, and inductive systems.

The skin losses of a litz wire consist of two primary effects:

1. Skin effect of individual litz strands: 
   Each individual strand within a litz wire experiences RMS and skin losses similar to a single solid wire. These are proportional to the square of the strand current amplitude, or the square of the total current through the litz cable.
    
2. Internal proximity effect: 
   Within the magnetic field generated by all litz strands, each individual strand experiences additional internal proximity losses. These are proportional to the square of the local magnetic field amplitude, and thus also proportional to the square of the total current through the litz cable. Specifically for strands with a circular cross-section, the current distributions of these two effects are orthogonal. Therefore, both types of power loss are additive, and the total losses are proportional to the square of the current passing through the litz cable.
    

HF litz wire stands for High-Frequency litz wire. It is specially engineered to minimize current losses at high frequencies – for instance, in transformers, induction coils, or charging systems for electromobility.

A typical HF litz wire consists of multiple enamelled single strands (copper or aluminum) twisted spirally. The specific stranding pattern, insulation type, and overall geometry determine the resulting electrical and mechanical properties.

Stranding refers to the spiral bundling of multiple wires to form a litz wire. The construction can range from simple (single-layer) to highly complex (multi-layer, counter-stranded) depending on the required flexibility and electrical performance.

The lay length defines the distance a wire layer travels to complete one full turn around the litz circumference. It directly influences flexibility, roundness, and current flow uniformity. Generally, longer lay lengths increase flexibility, while shorter ones reduce it.

Reproduducibility is the ability to manufacture a litz wire repeatedly with exactly the same parameters. This is critical for series production and subsequent orders. PACK LitzWire documents all manufacturing data internally to guarantee this consistency.

Depending on the application, the degree of flexibility or stiffness can be vital. Flexible conductors can withstand mechanical movement, vibration, and repeated bending, whereas stiffer litz wires might be better suited for certain automated winding processes.

From an electrical engineering perspective, the skin effect is the decisive factor for AC currents, especially at high frequencies: current is displaced to the edges of the conductor, reducing the effective cross-section.

To counter this, many thin, enamelled strands (HF litz wires) are used to increase the total conductive surface area, significantly reducing AC resistance and heat generation. Ideally, the thickness of each individual strand should be less than twice the skin depth at the operating frequency to fully utilize the conductor's capacity.

The conductor cross-section defines the electrical resistance and maximum current capacity. However, in high-frequency applications, the distribution of that area is just as important as the total area: an identical cross-section conducts AC better if it is split into many thin, insulated strands, thereby mitigating the skin effect.

Bare wires are uncoated and often intended for further processing (e.g., plating or external insulation). Enamelled wires feature a thin, high-performance insulation layer that prevents short circuits between individual strands.

The primary advantage of HF litz wires is the drastic reduction in AC resistance and power loss at high frequencies. This is achieved because the litz wire consists of many individually insulated (enamelled) strands that mitigate the current displacement (skin effect) seen in solid conductors of the same area. This allows the entire material cross-section to be used effectively, resulting in lower heat generation and significantly higher efficiency.

Uniform, compact stranding improves current flow and reduces power losses. Irregular geometries can intensify skin and proximity effects, thereby reducing overall efficiency.

In electrical engineering, high frequency typically begins around 10 kHz. In these ranges, specialized litz wire construction becomes essential for minimizing losses in passive components.

HF litz wires are classified by the temperature class of the strand (e.g., V155), the material (usually copper), the number of strands, the strand diameter, and the outer insulation (e.g., nylon yarn No. 63, single-covered). Example: V155, 7×0.10 mm CuL, 1x63.

It refers to the energy lost during AC operation due to skin and proximity effects.

The foundation of a high-quality litz wire is an enamelled copper wire manufactured to strictly defined criteria. The precision of subsequent processing steps – such as (multi-stage) stranding, outer insulation (yarns, foils, or extrusion), and gentle profiling – defines the quality of an HF litz wire. PACK LitzWire documents all manufacturing data internally. High-quality litz wires are always reproducible and certified.

Copper is the standard conductor due to its exceptional conductivity and formability. For specialized applications, we also use aluminum, silver-plated copper, or various custom alloys.

Copper offers superior conductivity and mechanical stability. Aluminum is more cost-effective and lighter but requires a larger volume to achieve the same resistance – a key consideration in weight-sensitive applications like e-mobility.

In an enamelled litz wire, each individual strand is coated with an ultra-thin layer of high-performance enamel. This insulation prevents internal short circuits, improves high-frequency performance, and enables compact windings.

Insulation classes (e.g., F, H) define the maximum permissible operating temperature, indicating the thermal resistance of the enamel or insulation.

Typical steps include wire drawing, enamelling, stranding, outer insulation (covering), and potentially profiling or braiding, followed by rigorous quality testing and final spooling.

Profiling involves shaping round litz wires into a defined geometry (e.g., square or rectangular) to maximize the fill factor within a given installation space or to achieve specific electrical characteristics.

Braiding involves crossing multiple stranded bundles around a core. This results in extremely flexible, robust structures with high current-carrying capacity.

It is defined based on the desired flexibility and electrical properties and is monitored via computer control. Maintaining constant lay lengths is a critical factor for ensuring reproducibility.

Every litz wire we manufacture is documented with exact product parameters and production-specific metrics (e.g., tensile force). These datasets allow us to manufacture identical products years later – a significant quality advantage for our customers.

Through continuous monitoring: strand diameter, enamel thickness, stranding parameters, dielectric strength, profile dimensions, and mechanical resilience are measured and documented throughout the production process.

In-house manufacturing translates to total control over every parameter – from the initial drawing of the wire to the final litz product. This ensures maximum quality, short lead times, and guaranteed traceability.

RUPATEX® is a premium product brand from PACK LitzWire, representing high-quality single wires (pure or tinned copper) with triple-layer insulation. These wires allow for direct tinning without prior stripping and eliminate the need for separate layer insulation.

Copper is 100% recyclable. Our modern manufacturing processes at PACK LitzWire minimize material waste and optimize energy efficiency. We also undergo regular ESG (Environmental, Social, and Governance) scoring by relevant financial institutions.

The enamel is applied in a continuous process and baked in high-temperature ovens. Multi-layer systems are used to enhance dielectric strength and thermal resistance. Technical properties often depend on wire diameter, specifically regarding tolerances for electrical resistance and outer diameter. All parameters comply with the IEC 60317 standard for Europe and Asia.

We employ numerous testing and monitoring procedures, including measuring lay length, dielectric strength (high voltage), outer diameter, electrical resistance, and tensile load capacity.

Several proven contacting methods are available for HF litz wires. In addition to classic soldering, methods such as hot crimping or ultrasonic welding are widely used. Modern techniques like friction welding also provide highly reliable, low-resistance connections.

Tolerances are governed by relevant standards as well as the specific cross-section, material, and construction of the product. Allowable deviations are typically defined in the technical datasheet or the corresponding set of standards.

Depending on the complexity and quantity, this can range from a few days to several weeks. Small batches or samples can often be produced on short notice.

A sample litz wire is used to validate the design and parameters within a customer’s project. It is manufactured under series production conditions but in small quantities.

We produce according to national and international standards such as DIN, EN, IEC, VDE, and UL. These standards ensure that electrical, thermal, and mechanical properties remain at a consistently high level.

DIN standards generally define technical standards across various industries. VDE standards specifically regulate electrical safety and material quality, serving as a binding foundation for electrical components.

All products are manufactured under a certified quality management system according to DIN EN ISO 9001. VDE and UL certificates for specific product groups are also available for download.

UL (Underwriters Laboratories) certificates are recognized globally. They document that products have been tested and approved for use in North American markets – a critical factor for global OEMs.

Every production batch is electronically monitored. We record parameters such as diameter, enamel thickness, stranding metrics (lay length and direction), dielectric strength, profile dimensions, and mechanical resilience. Any deviations are corrected immediately.

Every single strand undergoes an automated in-line test. Only defect-free wires enter the stranding process, ensuring consistent electrical properties across all batches.

Each litz wire is assigned a unique identification number that tracks all process data – from the raw material to the final spool. This allows every batch to be fully traced and reproduced.

Litz wires undergo defined insulation tests, including checks for dielectric strength (e.g., via spark tester) and insulation diameter (e.g., via laser). This ensures stability under continuous load and prepares the wire for further processing (e.g., with impregnating varnishes).

Our lab is dedicated to continuous quality assurance and new product development. We perform material analysis, cross-section examinations, and long-term service life tests.

A test report documents all measurement results for a batch – such as conductivity, diameter, enamel thickness, and mechanical resilience. These reports are available to customers upon request.

It indicates the voltage an insulation can permanently withstand without breaking down. The dielectric strength (or breakdown strength) of an HF litz wire depends heavily on its insulation system. Special HF litz wires for high-safety requirements (e.g., RUPALIT® Safety) feature reinforced insulation (e.g., at least three insulation layers).

Microscopic particles or residues can cause defects at any stage. Therefore, all manufacturing steps are performed under strictly controlled conditions to ensure consistently high quality.

Calibrated machines ensure consistent production parameters. Deviations in torque or tensile force are automatically detected and corrected.

All testing and manufacturing personnel are regularly certified according to internal standards. Training ensures that testing procedures are followed precisely as specified.

Through efficient energy and material usage, closed cooling systems, and the use of recyclable materials. All our processes are audited for sustainability.

Electrical and mechanical characteristics must be perfectly coordinated to minimize losses and maximize service life. Precise calculations are the foundation of successful engineering.

Selecting the right litz wire depends primarily on the requirements of the specific component or power electronics. Key figures include the conductor cross-section, the construction (number and diameter of strands), the material, and the type of insulation. Current capacity, bending radius, temperature range, and skin and proximity effects also play critical roles.

LiWiCalc® is a high-frequency calculator developed by the Fraunhofer Institute IISB. In collaboration with Fraunhofer, PACK LitzWire has created a specialized environment to calculate power losses and current densities of PACK HF litz wires in real time.

Designing passive components for power electronics requires balancing a variety of parameters. Engineers must harmonize electrical, mechanical, and thermal requirements to ensure optimal function. Selecting the appropriate HF litz wire is a complex task, as numerous factors influence performance.

The configurator allows users to enter two of the following three core parameters: single wire diameter, number of strands, or desired copper cross-section; the system then calculates the third parameter. Additionally, specifying the type of outer insulation is always a mandatory requirement.

Engineers typically start with the electrical specifications of the power converter (input/output voltage/current, switching frequency, target efficiency). Winding design involves determining the number of turns and the wire type. For high-frequency applications, the selection of litz wire is paramount. Engineers must account for constraints like available winding space, thermal management, and cost. Tools like RuPaFox® and LiWiCalc® provide essential support in this integrated process.

We use standard metric units: millimeters (mm) for diameter, square millimeters (mm²) for cross-section, and amperes (A) for current intensity.

This value indicates how many meters of a specific litz wire weigh one kilogram. It is calculated from the cross-section and material density – essential for both technical calculations and logistics.

Cross-section = Number of single strands × (π × (strand diameter/2)²). 

The result determines the current carrying capacity and the total resistance.

Lay length is the distance a conductor travels to complete one full (360°) turn around the litz wire circumference. It is typically specified in mm or cm.

In addition to our flagship HF calculators, we provide diameter, cross-section, lay length, and length-to-weight ratio calculators – available directly online or as technical PDF tables.

Generally, longer lay lengths increase flexibility, while shorter ones reduce it.

To calculate the outer diameter, please use the RuPaFox® product configurator. For every calculation, the configurator prominently displays the following results:

• Total Diameter: The calculated outer diameter of the litz wire, determined both with and without outer insulation.
• Copper Cross-section: The total conductive copper area of all strands, convertible to AWG.
• DC Resistance (min): The minimum DC resistance of the litz wire at 20°C, based on minimum single wire resistance.
• DC Resistance (nom): The nominal DC resistance at 20°C, a fundamental property for evaluating ohmic losses.
• DC Resistance (max): The maximum DC resistance at 20°C, which accounts for potential wire breaks in configurations with more than 25 strands.
• Meters/kg: The total length of litz wire per kilogram of finished product, essential for material and weight estimations.
• Number of Strands: The total number of individual wires, explicitly displayed when derived from a target cross-section or diameter.

Please use our RuPaFox® configurator for this calculation.

Yes. Our compendium includes reference tables for typical cross-sections, resistances, and weight data. Additionally, our online tools offer interactive calculation capabilities.

Conventional calculations are indispensable in power electronic design for approximating electrical losses, current displacement (skin and proximity effects), temperature rise, and current carrying capacity. These models provide an essential basis for the pre-selection of conductor cross-sections and stranding concepts.

However, their limits lie in the fact that they are based on idealized assumptions. In practice, numerous factors influence the real behavior of a litz wire that cannot always be calculated with absolute precision. These include:

• The specific stranding geometry and manufacturing tolerances.
• The interaction between litz wire, insulation, and the specific application.
• Mechanical influences during processing (bending, winding, pressing).
• Thermal conditions during real-world operation.
• Interactions with adjacent conductors, cores, or shielding.

Especially at high frequencies and power levels, these effects can cause calculated values to deviate from actual performance. Therefore, alongside theoretical design, experience in litz wire manufacturing is crucial for an optimal result. We view calculations as one part of a holistic design process, combining theoretical know-how with decades of practical expertise.

No. Current calculations are based on the specific material parameters of copper.

Any change in parameters (frequency, temperature, construction) should trigger a recalculation, as small changes can have significant impacts on losses and thermal performance.

HF litz wires are used wherever high-frequency alternating currents are present – for example, in transformers, induction systems, power electronics, charging infrastructure, medical technology, and aerospace.

They minimize current displacement losses (skin and proximity effects) and enable compact, low-loss windings, thereby increasing the efficiency and service life of components.

E-mobility demands lighter, high-current conductors with minimal power loss. HF litz wires with optimized cross-sections and specialized insulation systems fulfill these requirements reliably.

In imaging, diagnostics, and implant technology, litz wires must be highly flexible and electrically precise. PACK LitzWire manufactures reproducible, specialized litz wires with defined geometries for these purposes.

In this sector, low weight, temperature resistance, and absolute reliability are paramount. HF litz wires are found in sensors, actuators, and power supply systems of modern aircraft.

In inverters, wind turbines, and photovoltaic systems, they are used for high-frequency conversion and power transmission, helping to minimize energy losses.

HF litz wires are specifically engineered for high frequencies and compact component sizes. Standard litz wires are primarily used for low-frequency power transmission or in control lines.

As electronics and sensors become increasingly smaller, litz wires must be manufactured even finer and more precisely. This requires high-precision stranding and enamelling technologies.

Automated testing systems and AI-controlled machine processes ensure consistent quality and reduce reject rates. PACK LitzWire relies on real-time data and adaptive process control.

AI analyzes process data to detect deviations early. It optimizes parameters like torque or tensile force, increasing both reproducibility and energy efficiency.

Current research focuses on materials with higher conductivity and better thermal stability – such as silver-plated copper alloys, nanocomposites, and recycled metals.

In weight-critical applications, partially yes – for instance, in vehicle wiring. However, for high-frequency or high-precision applications, copper remains the leading material.

Copper is fully recyclable. PACK LitzWire reduces material consumption through precision manufacturing, utilizes energy-efficient machinery, and prioritizes closed-loop cycles.

With a growing focus on energy efficiency and sustainability, new testing criteria and documentation duties are being introduced – such as life cycle data and recyclability metrics.

With the rise of silicon carbide (SiC) and gallium nitride (GaN) semiconductors, switching frequencies and voltage edge steepness are increasing dramatically. The trend is toward litz wires with highly densified bundling where the fill factor nearly matches that of a solid conductor, while maintaining essential high-frequency properties (skin/proximity effect mitigation).

"Made in Germany" stands for precision, process stability, and standard-compliant manufacturing. Proximity to universities and research institutions also fosters innovation and knowledge transfer. For decades, PACK LitzWire has collaborated on research projects with leading electrical engineering departments at major universities.

Close cooperation with research partners allows simulation and practical testing to intermesh seamlessly – a decisive advantage when developing new HF litz wires. These insights also directly influence the development of our production machinery and processes.

Digital twins and automated calculation tools shorten development times and improve coordination between design and production. We always emphasize the production of prototypes and samples to validate our calculations.

Yes – automotive, medical, aerospace, and industrial electronics each have unique requirements regarding insulation, temperature resistance, flexibility, and compliance standards.

Frequency, current, temperature, mechanical stress, and installation space are the key factors. The PACK LitzWire product configurator, RuPaFox®, helps you quickly identify the best solutions.

Important details include the strand diameter, temperature class, number of strands, and any required insulation. The more precise the information, the more accurate our quotation.

Sampling allows you to test litz wires before series production. This enables customers to verify electrical and mechanical properties under real-world conditions.

Depending on the structure and quantity, it typically takes between a few days and two weeks. Our in-house manufacturing allows us to react on short notice.

Yes. PACK LitzWire archives production parameters for all batches, allowing us to accurately reproduce designs even after many years.

Small batches starting from just a few meters or kilograms are possible. We also manufacture specialized solutions in small quantities with full industrial process quality.

Yes – upon request, litz wires can be fitted with connectors, ferrules, or insulation sleeving. Custom finishing of existing products is also available. Learn more here: Custom Finishing

Standard products are available for immediate shipment. Custom productions generally require 2–6 weeks depending on the design. All delivery commitments are binding.

You can do this via our product pages or the contact form. Our technical experts are ready to assist you with selection and documentation.

It is an online tool that displays products currently in stock. Filters help you find the right cross-sections, insulation, or spool sizes immediately.

We use various spool sizes depending on your requirements. Custom packaging according to your specific instructions is also available upon request.

Yes. Custom geometries, profiles, or insulation systems are implemented following technical consultation – including sampling and full documentation.

We ship worldwide. PACK LitzWire works with certified logistics partners and documents every shipment for full traceability.

Technical development consulting, Design-for-Manufacturing, advice on connection technologies, project and prototyping support, material and insulation consulting, documentation and compliance advice, logistics and supply chain services, training, and knowledge transfer.

Inquiries are typically answered within 1-2 business days. Technical questions are clarified directly by a specialized expert.

They combine technical expertise with a dedicated service focus. You speak directly with experts – without the detours of call centers or support tickets.

Through sampling, simulation, parameter optimization, and close coordination between development and manufacturing – from the initial idea to series production.

Short distances, stable supply chains, high process quality, and full transparency regarding materials and standards compliance.

When developing litz wires, we consider not only electrical properties but also further processing steps (contacting, winding, joining). This is a core strength of PACK LitzWire. Our decades of experience and network of partners help eliminate unnecessary effort for our customers.

Because we combine deep knowledge, manufacturing excellence, and comprehensive service. As a partner, PACK LitzWire supports its customers long-term – from development to reproduction.

Yes, spools can be returned to the following address:

Rudolf Pack GmbH & Co. KG
Bockshard 22
51580 Reichshof
Germany

Please ensure the spools are intact, clean, and were originally supplied by PACK.

For detailed information, please refer to our spool overview in the download section.

HF litz wire is typically contacted by tinning, as the individual strands are enamelled. The litz wire end is twisted and moistened with flux, then held in molten solder at approximately 400 °C or tinned with a hot soldering iron. 

During this process, the insulating enamel burns away, and the solder electrically connects all strands.