ULTEM - Amorphous Polymer

Port Plastics Technical Library

The ULTEMate Amorphous Polymer for Semiconductor Applications

If you spend much time working on applications for the Process Tools used to make IC chips on wafers, then you have likely come across parts fabricated from ULTEM™ resin. It's recognizable by its transparent amber color. ULTEM™ was first introduced by General Electric Plastics in 1982 and is also known by its chemical name, polyetherimide or PEI. What makes PEI unique is that it is a thermoplastic amorphous material with properties not typical of amorphous materials. This uniqueness brings significant value to the semiconductor industry. The following key areas make ULTEM™ PEI quite the value for the performance:


As the name ULTEM™ suggests, PEI resin delivers outstanding elevated temperature performance. Due to a 422°F Glass Transition temperature, the polymer maintains excellent mechanical properties at elevated temperatures with a continuous operating temperature of 340°F.


When compared to its engineering thermoplastic amorphous counterparts (PPSU, Polycarbonate), ULTEM™ PEI offers superior mechanical properties. The tensile and flexural properties of PEI are typically +20% higher while it maintains its toughness even at elevated temperatures.


ULTEM™ PEI offers an extremely high Dielectric Strength, which is a measure of a material's capability to act as an insulator under increasing voltage. Unfilled natural ULTEM™ offers a Dielectric Strength over twice that of its closest amorphous counterparts.


In its natural unfilled state, ULTEM™ PEI offers very low smoke propagation as well as UL94-V0 flame resistance as low as 1/8-inch thickness.

Comparison of Properties

ULTEM™ PEI Standard PPSU GP Polycarbonate
Tensile Strength @ Yield 17,000 psi 12,000 psi 9,300 psi
Flexural Modulus 500,000 psi 420,000 psi 340,000 psi
Tensile Modulus 500,000 psi 385,000 psi 340,000 psi
Dielectric Strength 830 V/mil 380 V/mil 378 V/mil

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The ULTEMate Amorphous Polymer for Semiconductor Applications