Shin-Etsu Pure Sealant S-type — Ultra-Low Siloxane Outgassing, One-Component AcetoneType Room-Temperature-Curing Silicone Sealant for Wafer-Level Low-Contamination Cleanrooms

Shin-Etsu Pure Sealant S-type is a one-component silicone sealing material that cures at room temperature by reacting with atmospheric moisture to form an elastic seal with outstanding adhesion. While retaining ultra-low siloxane outgassing, it further reduces the amount of released organic compounds to a level unachievable by conventional sealants in wafer adsorption tests, and bonds to virtually any substrate. It is the flagship grade engineered for the highest-cleanliness, lowest-wafer-contamination cleanroom joints and semiconductor production equipment.

• Excellent durability, heat resistance and weather resistance
• Low-molecular-weight dimethyl siloxane is almost not evaporated, ensuring ultra-high cleanliness
• Outstanding adhesiveness — adheres to most any material
• Substantially lower level of released organic compounds
• Performs far better than conventional sealants in wafer adsorption tests
• Easy-to-use one-component type; simply squeeze from the cartridge to apply
• Low-molecular-weight siloxane as low as 40 ppm; phosphorous, boron and antimony all below 1 ppm
• 100% cohesive failure — high adhesion reliability

General Properties (not specified values)

Sheet properties measured per JIS K 6249 (cured 7 days at 23℃ / 50% RH); H-block per JIS A 5758 (float glass; 14 days at 23℃ / 50% RH, then 14 days at 30℃).

Cleanliness Verification

• Cyclic siloxane extraction (D3–D20): only D18–D20 detected (D18 = 10, D19 = 30, D20 = 80 ppm), totaling ~120 ppm; D3–D17 below the 10 ppm detection limit — far lower than the conventional product (ΣD11–20 = 9,890 ppm).
• Si-wafer outgassing adsorption test (JACA No.34): organic compounds adsorbed onto the wafer surface are far lower than common sealants, achieving performance unattainable by conventional products — ideal for semiconductor wafer processing.

Colors & Packaging

• Colors: Light gray, ivory
• Packaging: 330 ml cartridge (standard packaging: box of 20 cartridges)

Sealing of interior trim joints and around air filters (HEPA/FFU) in cleanrooms used for the manufacturing and processing of semiconductors and other precision electronic materials — especially where the lowest wafer-level organic contamination and the broadest substrate-bonding range are required.

Q1｜What is the key difference between S-type and standard Pure Sealant?

Both are one-component, ultra-low-outgassing cleanroom sealants but differ in cure chemistry. The S-type is  (oxime) type, which further reduces organic compounds adsorbed onto wafers and achieves performance unattainable by conventional products in wafer adsorption tests; the standard grade is MEKO oxime type. The S-type bonds to a broader range of substrates and has lower siloxane content (40 ppm vs 60 ppm) but is offered only in light gray and ivory.

Q2｜How does it cure? Is heat or two-part mixing required?

No. It is a one-component, room-temperature-curing (acetonetype) product that cures by absorbing atmospheric moisture, slowly releasing acetoneduring curing. Tack-free time is only ~3 min at 23℃ / 50% RH; cure speed varies with temperature and humidity.

Q3｜What materials does it bond to?

It offers outstanding adhesion and adheres to most any material, achieving 100% cohesive failure in H-block testing. Bonding surfaces must be cleaned of oil, dust and contaminants beforehand.

Q4｜What storage and handling precautions apply?

Store in a cool (5–25℃), dry place away from direct sunlight. Use promptly after opening; reseal the unused cartridge and keep it cool and dark. Avoid application in cold or humid conditions, which can cause poor curing/adhesion. Clear and white grades may slowly yellow in storage without affecting performance. The cured surface cannot be painted. Keep caulking-gun air pressure below 0.3 MPa.

Q5｜What safety measures are required during use?

Keep the area well-ventilated during work and for at least 24 hours after application. Uncured sealant irritates skin and mucous membranes; avoid eye contact — if it enters the eyes, flush with water for 15+ minutes and seek medical advice. is released during curing, so ventilate adequately; read the SDS/MSDS before use.

Q6｜When should I choose S-type over the standard grade?

Choose S-type when the application demands the lowest wafer-level organic contamination (e.g., advanced semiconductor wafer processing) or the broadest substrate-bonding range; choose the standard Pure Sealant when you need a wider color range (white, translucent, etc.) or higher hardness (Shore A 44).