Taped Litz Wire
Taped high frequency Litz wire constructions are mainly suitable for applications requiring a high break down voltage. Taping gives Litz wire improved capability to withstand flexing and mechanical stress. Self-adhesive tape material increases protection against re-opening during and after manufacturing processes and thus secures the compliance with defined creepage distance.
Some tapes can be thermally sealed, when used in conjunction with certain wire enamel types.
The individual wires excellent adhesion and bonding characteristics can be achieved. Thermally sealed tapes can be selected from a number of material types for special applications all promoting various degrees of flexibility and mechanical protection for the Litz wire construction.
Features and Benefits of Tapes
| Variants | Dielectric strength | Flexibility | Splicing | Contacting |
|---|---|---|---|---|
| Standard | high | very good | good | very good |
| Thermally Sealed | elevated | medium | very good | very good |
| Self-Adhesive | very high | good | very good | good |
Dimensions
| Content | ||
|---|---|---|
| Diameter of single wires | 0.040-0.500 | mm |
| Outer diameter of litz wire | 0.50-10.0 | mm |
| Overlapping single tape | 50 or 67 | % |
| Numbers of tapes (max.) | 2 | |
Applications
- Inverters
- RF transformers
- RF transducers
- RF chokes
- Inductive charging
- Onboard charger
- DC/DC converters
Technical Data Sheet of Tapes
| PET | PEN | PI | ||
|---|---|---|---|---|
| Description | Polyester | Polyethylene Naphthalat | Polymide | |
| Color | transparent | transparent | brown | |
| Standard | PET | PEN | PI | |
| Breakdown voltage | kV | 5.0 (VDE 0345) | >5.0 (JIS C 2318) | 5.0 (ASTM D 149) |
| Insulation class (UL) | °C | 105 (A) | 180 (H) | 200 (C) |
| Insulation class (VDE) | °C | 130 (B) | - | 200 (C) |
| Dielectric constant | εr | 3.3 (VDE 0345) | 2.9 (JIS C 2318) | 3.4 (ASTM D 150-92) |
| Flammability | °C | 400 (VDE 0345) | - | V-0 (IEC 60695-11-10; UL94) |
| UL-File No. Tapes* | E53895 | E206562 | E39505 | |
| Processing | fusible | fusible | mechanical stripping | |
| Thermally Sealed | PET | PEN | PI | |
| Breakdown voltage | kV | 5.4 (ASTM D 149-81) | - | 5.0 (ASTM D 149) |
| Insulation class (UL) | °C | 105 (A) | - | 200 (C) |
| Insulation class (VDE) | °C | 130 (B) | - | 200 (C) |
| Dielectric constant | εr | 3.26 (ASTM D 150-81) | - | 3.4 (ASTM D 150-92) |
| Flammability | n.a. | - | V-0 (IEC 60695-11-10; UL94) |
|
| UL-File No. Tapes* | E93687 | - | E39505 | |
| Processing | fusible | - | mechanical stripping | |
| Self-Adhesive | PET | PEN | PI | |
| Breakdown voltage1 | kV | 5.0 | 5.0 | 5.0 |
| Insulation class (UL) | °C | 180 (H) | 180 (H) | 180 (H) |
| Dielectric constant | εr | 3.2 (JIS C 2318) | 2.9 (JIS C 2318) | 3.3 (JIS C 2318) |
| Flammability | - | flame retardant (UL 501) | flame retardant (UL 501) |
|
| UL-File No. Tapes* | E93687 | E206562 | E39505 | |
| Processing | fusible | fusible | mechanical stripping |
1 approximate value
* the used foils are variants of UL recognized products
Other materials on demand
Special constructions with VDE-approval for high voltage applications available:
EFOLIT-product family
VDE – certified acc.: DIN EN 60950, annex U
DIN EN 61558, annex K
DIN EN 60601, annex L
Taped high frequenzy litz wire EFOLIT
VDE-certified triple reinforced insulated high frequency litz wire with self adhesive sPET and sPEN film material for diameters up to 5.0 mm. Constructions with self adhesive tapes allow very high break down voltages as well as high flexibility. Compliance with application specific demands for air and creepage distances is covered in perfect manner.
according to specification:
DIN EN 62368, Annex J
DIN EN 60950, Annex U
DIN EN 61558, Annex K
DIN EN 60601, Annex L
Dimensional range EFOLIT
| Construction | |
|---|---|
| Diameter single conductor | 0.030 - 0.300 mm 48 - 28 AWG |
| Total conductor cross section | 0.100 - 10.600 mm² |
| Outer diameter Litz Wire (approx.) | 0.500 - 5.000 mm 24 - 4 AWG |
| Tape insulation (min.) | 3-layers |
Operating range EFOLIT
| Winding Wires for reinforced insulation | |
|---|---|
| Max. rated and peak voltage | 1000 Vrms, 1414 V peak |
| Max. frequency | 500 kHz |
| Temperature class | F / 155°C / 311°F H / 180°C / 356°F |
Labeling EFOLIT
| Validated Standards | Code | sPET | sPEN |
|---|---|---|---|
| DIN EN 60950, 61558, 60601 VDE-Reg.-No.: E078 (nom. test voltage 6,0 kV) | EFOLIT 11F | class F with enamel type TI ≥ 155°C / 311°F | - |
| EFOLIT 21H | - | class H with enamel type TI = 155°C / 311°F |
|
| EFOLIT 22H | - | class H with enamel type TI ≥ 180°C / 356°F |
|
| DIN EN 60950 VDE-Reg.-No.: E450 (nom. test voltage 3,0 kV) | EFOLIT 13F | lass F with enamel type TI ≥ 155°C / 311°F | - |
| EFOLIT 23H | - | class H with enamel type TI = 155°C / 311°F |
|
| EFOLIT 24H | - | class H with enamel type TI ≥ 180°C / 356°F |
TI = Temperature Index
Technical Data Tape Material
| Self-Adhesive Tape | sPET | sPEN |
|---|---|---|
| Description | Polyester | Polyethylene Naphthalate |
| Color | transparent | transparent |
| Break down voltage | 5.0 kV | 5.0 kV |
| Temperature class (UL) | 130°C / 266°F (B) | 180°C / 356°F (H) |
| Permittivity (JIS C 2318) | 3.2 | 2.9 |
| Flammability (UL 510) | - | flame retardant |
| UL File No. Tape* | E 93687 | E 206562 |
| Processing | fusible | fusible |
* The used tapes are variants of UL recognized products
Litz Wire Attributes
| Typical Litz wire: | 105 x 0.08 mm OSP18 |
|---|---|
| Overal diameter litz wire: | 1.05 to 1.15 mm (approx. AWG 18) |
| Elongation: | 10 % |
| Resoftening temperature Smartbond: | > 130°C / 266°F |
| Solderability: | 4 sec. at 420°C / 788°F |
| Breakdown voltage (non-bonded twist): | 1,200 V |
| Elongation: | 18 % |
| Cut through temperature: | 260°C / 500°F |
| Bond strength (helical coil): | 1,700 cN after 180°C / 356°F hot air bonding 1,900 cN after 210°C / 410°F hot air bonding |
| Litz wire diameter: | 0.50 mm to 3.50 mm |
| Base insulation of single wire: | high temperature modified Polyurethane P180 for temperature class 180°C / 356°F (H) |
| Bond coat on litz wire: | modified thermoplastic |
| Bonding temperature: | > 170°C / 338°F |
| Approvals: | UL listed SGS-data available |
Technical values of a typical product
| Standard litz wire | Served litz wire | Selfbonding litz wire | Smartbond | |
|---|---|---|---|---|
| Stability of coil | - | good | medium | good |
| Flexibility / windability | soft | more stiff | soft | soft |
| Bonding process | - | solvent | hot air | hot air |
| Mechanical protection | avg | good | avg | good |
| Surface and haptic | - | rough | avg | smooth |
| Second adhesion step without additional adhesive | no | no | limited | yes |
Degree of Overlapping
The degree of overlapping of two adjacent tape windings is defined by the gradient angle between tape and litz wire during the taping process. The overlapping determines the number of tape layers located on top of each other and thus the insulation thickness of the litz wire.
