When can PPS replace PEEK for cost?
Wet Process components have several requirements in common in terms of mechanical properties required, dimensional stability requirements, chemical resistance required and low outgassing. That said, one property that is not always needed in wet process tools is elevated thermal performance.
One potential candidate for cost reduction in wet process applications that use PEEK is semiconductor grade PPS. Don’t get me wrong, PEEK is a fantastic choice for excellent chemical performance and mechanical properties, but you pay for the thermal properties of PEEK. In some select components PPS could bring value.
Below are some comparisons for PEEK vs Semiconductor Grade PPS:
Mechanical Properties
| Critical Property | Semiconductor Grade PPS | Industry Standard PEEK |
|---|---|---|
| Tensile Modulus psi | 500,000 | 630,000 |
| Flex Modulus psi | 575,000 | 600,000 |
| CLTE | 2.8 | 2.6 |
| Moisture Absorption @ 24 hrs | 0.01 | 0.1 |
| Heat Deflection Temp @ 264 psi | 250°F | 320°F |
| Relative Cost | $ | $$ |
Chemical Resistance Properties
| Chemistry | PEEK | PPS |
|---|---|---|
| Strong Acids | O | O |
| Weak Acids | + | + |
| Strong Base | + | + |
| Weak Base | ++ | ++ |
| Salts | ++ | ++ |
| Halogens | + | O |
| Phenols | ++ | + |
| Aliphatic Hydrocarbon | ++ | ++ |
| Aromatic Hydrocarbon | ++ | ++ |
| Chlorinated Hydrocarbon | O | ++ |
| Ketones | + | + |
| Amines | ++ | ++ |
| Alcohols | ++ | ++ |
| Esters | + | ++ |
| Aldehydes | ++ | ++ |
Outgassing Properties
| Material | %TML | %CVCM | %WVR |
|---|---|---|---|
| PEEK | 0.26 | 0 | 0.12 |
| Semicon PPS | 0.04 | 0 | 0 |
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| Nucleation in Polypropylene and Semicon Process Tools |