---
type: "Technical Data Sheet"
title: "CMC 278XX – Technical Data Sheet"
description: "CMC 27805 to 27840 are highly robust insulation films available as rolls, sheets or die-cut parts."
resource: "https://datasheets.cmc.de/pdf/cmc-278xx-en.pdf"
language: "en"
product: "CMC 278XX"
product_family: "cmc"
document_date: "2021-03"
status: "stable"
translation: "/cmc-278xx-de.md"
generated: { by: "process:cmc-datasheets/0.1.0", at: "2026-09-23T16:58:11Z" }
sources:
  - id: "pdf"
    resource: "https://datasheets.cmc.de/pdf/cmc-278xx-en.pdf"
    title: "Technical Data Sheet CMC 278XX"
    author: "CMC Klebetechnik GmbH"
    last_modified: "2021-07-07T14:09:18Z"
---

# CMC 278XX – Technical Data Sheet

> Material flame retardant polypropylene insulation film Original material Formex GK by ITW Electronic Components FORMEX UL file QMFZ2.E121855

[PDF data sheet (binding)](/pdf/cmc-278xx-en.pdf) · [Deutsche Version](/cmc-278xx-de.md)

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.

```text
 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

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

## Physical properties

| Property | Value |
|---|---|
| Density | 1.035 |

```text
 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

```text
 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

```text
                                                         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

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*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.*