IPA, Semiconductor Grade (High-Purity Isopropyl Alcohol) Storage & Tank Compatibility

Storing IPA, Semiconductor Grade (High-Purity Isopropyl Alcohol)? Start Here

Semiconductor-grade IPA is high-purity isopropyl alcohol (2-propanol, CAS 67-63-0) refined to electronic-grade specifications — typically ≥99.9% and up to 99.999% (5N) purity, with residual water often held to about 10 ppm and metallic/ionic impurities controlled to parts-per-trillion. It is the highest-volume cleaning and drying solvent in chip fabrication, used for final-rinse wafer drying (it displaces ultra-pure water and leaves no watermarks thanks to its low surface tension), photoresist-related cleaning, and general degreasing. Because IPA is fully miscible with water, it is also diluted with ultra-pure water for specific process steps. From a tank and equipment standpoint, IPA does not chemically attack common polyolefins, stainless steel, or fluoropolymers, so the material-of-construction decision turns almost entirely on managing a flammable liquid and protecting the chemistry's extreme cleanliness rather than on corrosion resistance.

Is Polyethylene (HDPE / XLPE) Safe for IPA?

Yes — for chemical compatibility, polyethylene is rated S (suitable). Published polyethylene resistance charts show HDPE and LDPE exhibiting little or no damage on prolonged exposure to isopropyl alcohol at ambient temperature, and poly tanks and totes are routinely used for IPA. The real constraints are not chemical: IPA is a flammable Class IB liquid (flash point ~12°C / 54°F) that can accumulate static charge, so an HDPE/XLPE installation must include bonding and grounding of all conductive components, vapor control, and an ignition-controlled (electrically rated) area. For high-purity semiconductor use, plain polyethylene may also contribute trace leachables, so fluoropolymer-lined or electropolished stainless wetted paths are preferred to preserve ppt-level cleanliness. Bottom line: poly is chemically fine for IPA; design the system around flammability and purity, not corrosion. Always confirm against the specific product SDS and your facility's fire code.

Material compatibility at a glance

Isopropyl alcohol is chemically benign toward polyethylene, polypropylene, stainless steel, and fluoropolymers, so material selection is driven by FLAMMABILITY and PURITY, not chemical attack. Polyethylene (HDPE/XLPE) is rated S (suitable) for IPA storage; for a flammable Class IB liquid, prioritize static control (bonding/grounding), vapor management, and an electrically rated installation. High-purity semiconductor service additionally favors fluoropolymer-lined or electropolished stainless wetted paths to protect the chemistry's ppt-level cleanliness.

Ratings: S suitable · C conditional / limited · U unsuitable. Verify against the cited resistance charts and your concentration/temperature before specifying.

The safety that actually matters

• Highly flammable (H225): Class IB flammable liquid, flash point ~12°C (54°F); vapors form explosive mixtures with air and can travel to a distant ignition source.
• Static ignition risk: IPA can accumulate electrostatic charge during transfer — bond and ground all containers and use explosion-proof, electrically rated equipment.
• Eye irritation (H319): Causes serious eye irritation; use chemical splash goggles and a face shield for transfers.
• CNS / narcotic effect (H336): Vapors may cause drowsiness or dizziness; provide adequate ventilation and limit inhalation exposure.
• Keep from heat and oxidizers: Store away from heat, sparks, open flame, and strong oxidizers; keep containers closed and vapor-managed.
• SDS governs: Hazard details and ratings are representative and SDS-dependent — follow the specific product SDS and applicable fire code for design, storage, and handling.

Common questions

Can I store semiconductor-grade IPA in an HDPE or XLPE poly tank?

Chemically, yes — polyethylene resists isopropyl alcohol with little or no effect at ambient temperature, so poly is rated S (suitable). The governing concern is flammability, not chemical attack: IPA is a Class IB flammable liquid, so the installation must include static bonding/grounding, vapor control, and an ignition-controlled area. For the highest-purity process steps, fluoropolymer-lined or electropolished stainless is often preferred to avoid trace leachables.

Why is IPA used for drying wafers instead of just water?

IPA has very low surface tension (~23 mN/m versus water's ~72), so during the final dry it displaces ultra-pure water from the wafer surface without leaving spots or watermarks, and it evaporates quickly and cleanly. This is the basis of Marangoni / IPA-vapor drying used to protect fine features. (Process detail is representative; follow your tool and process documentation.)

What makes it 'semiconductor grade' versus ordinary IPA?

Semiconductor or electronic grade is refined to far tighter specifications — commonly ≥99.9% up to 99.999% (5N), with residual water often around 10 ppm and metallic/ionic impurities controlled to parts-per-trillion. Exact limits are specification- and supplier-dependent; reference standards such as SEMI grades define the targets.

What are the main safety hazards when handling IPA?

Primarily flammability (H225) with a low flash point near 12°C, plus serious eye irritation (H319) and possible drowsiness/dizziness from vapor (H336). Control ignition sources, bond and ground equipment, ventilate, and wear eye protection. All hazard information is representative and SDS-dependent — follow the specific product SDS.