Dielectric Strength

ULTEMTM film technology offers exceptional dielectric strength, a key requirement in many electrical insulation applications. ULTEMTM films are comparable benchmark polyimide materials, offering a dielectric strength of approximately 5,000 Volts/mil when tested at a thickness of 2 mil or 50 microns.

Dielectric Constant and Dissipation Factor

Another attribute of ULTEMTM film is the low dielectric constant and dissipation factor. Although low or high absolute values of the dielectric constant may be desirable depending on the application, it is more important that the values remain stable. The dielectric constant and dissipation factor for ULTEMTM films were measured at GE Global Research Center. The films were tested and compared to commercially available industry standard benchmark materials. Dielectric performance was measured on films that were fully saturated with moisture and completely dried. Testing was performed at high frequency, and versus standard testing at 1 MHz.

In addition to the attribute of low dielectric constant, ULTEMTM films demonstrate a very stable dielectric constant when tested at various frequencies. The dissipation factor shows some sensitivity to frequency, however, the results of testing still show very good performance values. The data provided on Dielectric Constant Versus Frequency and Dissipation Factor Versus Frequency was supplied by Rogers Corporation.
The combination of low dielectric properties and stable dielectric properties may make ULTEMTM film an ideal candidate for high frequency electronic applications.

Moisture Properties

Moisture absorption can be a critical factor in the performance of many electronics applications. It affects the electrical performance, namely the dielectric constant and dissipation factor, as well as potentially affecting the process yield of secondary metallization. ULTEMTM film moisture performance was measured and compared to benchmark polyimide materials. ULTEMTM films demonstrated better moisture performance at both conducted test methods.
The amount of moisture that the material can absorb will also have an impact on the dimensional stability of the application.This measure of dimensional stability is often referred to as the coefficient of hydroscopic expansion (CHE). CHE measurements are very similar to measuring the coefficient of thermal expansion for materials (CTE), except the percentage of relative humidity is varied, instead of the temperature. Expansion of the films is measured over humidity at room temperature. The performance of ULTEMTM films is shown compared to a benchmark polyimide film.  


Another outstanding property of ULTEMTM film is its high modulus compared to most amorphous thermoplastic films. The modulus of the films was measured and compared to commercially available, commonly used products. As the data suggests, ULTEMTM film offers very similar tensile modulus compared to standard polyimide films.
Unlike crystalline materials, which demonstrate a rapid decrease in modulus due to the relatively low glass transition temperature, the amorphous nature of ULTEMTM film offers the additional benefit of gradual reduction in modulus as temperature increases.

Tear Strength

Tear performance of thin films is often critical to any secondary process that is performed on the film substrates. The tear strength performance is very dependent on the thickness of the film and how the film was converted. If dull trimming blades are used, it could cause a reduction in the tear strength of the film materials. Tear initiation measures the force required to start a tear in the film. Tear propagation measures the amount of force required to propagate a tear after it has been started in the film. ULTEMTM films’ tear propagation and tear initiation strengths were measured and compared to commercially available benchmark materials. The data shows that ULTEMTM films are similar in performance to the benchmark polyimide materials. Additionally, ULTEMTM films show consistent performance in the machine direction and transverse direction of the extrusion process.

Thermal Properties

Shrinkage or dimensional stability of high performance films can be critical to the performance of the end use application. The shrinkage of ULTEMTM films has been characterized by using the IPC TM–650 2.2.4 Method A test on a bare film.
The shrinkage in the ULTEMTM film materials is caused primarily by the manufacturing method employed to make the film. A small amount of stress in the film is relieved when the films are exposed to elevated temperatures. If lower shrinkage is desirable, the films can be heat stabilized to remove the shrinkage in the film up to the stabilization temperature. This has been demonstrated by experiments conducted by the GE Advanced Materials technology team. However, heat stabilized ULTEMTM films are not currently commercially offered by GE Advanced Materials.  

Product Property Summary