CMC 278XX – Technical Data Sheet

CMC 27805 to 27840 are highly robust insulation films available as rolls, sheets or die-cut parts.

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Issued: 2021-03

Product description

CMC 27805 to 27840 are highly robust insulation films available as rolls, sheets or die-cut parts. Key features are outstanding resilience against partial discharge, flame retardancy (UL94 V-0 or VTM-0), high breakdown voltage, good temperature performance (115°C) and virtually no hygroscopic behaviour. The material can also be supplied in a self-adhesive version, while retaining its flame-retardant properties.

 CMC Type                                               CMC 27805     CMC 27810          CMC 27817 CMC 27830        CMC 27840
 Formex                                                  GK-5BK         GK-10              GK-17            GK-30     GK-40
 Colours                                                  black                                  white / black
 Thicknesses in mm                                        0.127           0.25              0.43             0.76      1.02
 Tolerances in mm                                        ± 0.025       +0.08/-0.04       +0.08/-0.03        ±0.05     ±0.05

Mechanical properties

 Tensile strength in psi (machine/transverse dir.)      3700/3300                4400/3200             4000/3200    4000/3700

Physical properties

Property Value
Density 1.035 
 Flammability according to UL94                                    VTM-0                                     V-0
Property Value
Oxygen index according to ASTM D 2863 29%
Water absorption according to ASTM D 570 0.06% (mass increase)
Relative temperature index RTI according to UL 746B 115°C (electrical and mechanical)

Electrical properties

 Breakdown voltage in kVeff. according to ASTM D 149      ca. 11            ca. 16          ca. 20       ca. 29.5     ca. 33

Dielectric strength in V/mil according to ASTM D 149

                                                         ca. 2200          ca. 1620       ca. 1200       ca. 990     ca. 830
Property Value
(1 mil = 25.4 µm) Volume resistivity in ∙cm according to ASTM D 257 3.97∙1015
Dielectric constant according to ASTM D 150 1.9
Dissipation factor according to ASTM D 150 0.0023
High current arc ignition (HAI) according to UL 746A performance level category 0
High voltage arc tracking according to UL 746A performance level category 0
Hot wire ignition according to UL 746A performance level category 4
Comparative tracking index (CTI) according to ASTM D 3638 performance level category 0 (600 V)

Other properties

The technical data are average values and do not replace the user's own testing. Subject to change without notice. The PDF data sheet is binding.