CAS NO.60665-85-2 2,4,6,8-tetramethyl-2,4,6,8-tetrakis[3-(oxiranylmethoxy)propyl]cyclotetrasiloxane

Frequently Asked Questions

Q1: What is CAS NO.60665-85-2 and what is its chemical structure?

CAS NO.60665-85-2, also known as CS-697 or Coupling Agent 697, is a cyclic siloxane with four glycidyl ether functional groups. Its molecular formula is C28H56O12Si4 with a molecular weight of 697.08 g/mol. The cyclotetrasiloxane backbone carries four propyl glycidyl ether side chains, giving it an exceptionally high epoxy value of 0.55-0.57 mol/100g.

Q2: What makes CS-697 different from regular epoxy silane coupling agents like KH-560?

Unlike monofunctional KH-560 (CAS 2530-83-8), CS-697 features a cyclotetrasiloxane core with four reactive epoxy groups per molecule. This tetra-functional structure provides significantly higher crosslinking density, superior thermal stability, and enhanced mechanical performance in epoxy systems compared to single-point coupling agents.

Q3: What is the epoxy value of CS-697 and why is it important?

CS-697 has an epoxy value of 0.55-0.57 mol/100g, which is among the highest for commercial silane coupling agents. A high epoxy value means more reactive sites per molecule, enabling denser crosslinking networks, better adhesion promotion, and improved chemical resistance in final applications.

Q4: What are the typical applications of CS-697?

CS-697 is widely used in: LED packaging and chip underfill compounds; high-temperature PCB solder mask formulations; epoxy resin modification for enhanced thermal and mechanical properties; carbon fiber composite prepregs for aerospace applications; automotive high-temperature clear coats and 3C product hard coatings; and electronic potting compounds requiring excellent thermal cycling reliability.

Q5: What is the physical appearance and solubility of CS-697?

CS-697 is a colorless to pale yellow viscous liquid at room temperature. It is soluble in organic solvents such as toluene, acetone, THF, and other common organic solvents. It has a density of approximately 1.132 g/mL at 25°C and a boiling point above 250°C.

Q6: How should CS-697 be stored and what is its shelf life?

CS-697 should be stored in a well-closed container at 2-8°C in a cool, dry place away from light and heat sources. The low storage temperature helps maintain epoxy group stability. Avoid exposure to strong acids, strong bases, and high temperatures which may cause ring-opening reactions.

Q7: What safety precautions should be taken when handling CS-697?

CS-697 contains reactive epoxy groups that may cause skin, eye, and respiratory irritation. Operators should wear safety goggles, chemical-resistant gloves, and work in a well-ventilated area or fume hood. In case of skin contact, wash immediately with soap and water. The product is classified as GHS07 with H302-H315-H317-H319-H335 hazard statements.

Application Cases

Case 1: LED Packaging Encapsulant

A leading LED manufacturer integrated CS-697 into their silicone-epoxy hybrid encapsulant for high-power LED modules. Adding 2% CS-697 as a coupling agent significantly improved the adhesion between the encapsulant and the gold-plated lead frame, reducing delamination failures during thermal cycling tests (-40°C to 150°C, 1000 cycles) by over 60%. The high epoxy functionality provided denser crosslinking at the interface, resulting in superior moisture resistance and long-term optical stability of the LED packages.

Case 2: Carbon Fiber Aerospace Composite

An aerospace composite fabricator used CS-697 as a sizing agent for carbon fiber surfaces in epoxy prepreg applications. The tetra-functional epoxy siloxane formed strong covalent bonds between the carbon fiber surface and the epoxy matrix, improving interlaminar shear strength (ILSS) by 25% compared to untreated fibers. The enhanced fiber-matrix interface also reduced microcracking under impact loading, making the composite suitable for secondary aircraft structural components requiring high damage tolerance.

Case 3: High-Temperature PCB Solder Mask

A PCB manufacturer incorporated CS-697 into their lead-free solder compatible solder mask formulation for automotive electronics. The coupling agent improved adhesion to copper traces and FR-4 substrate during repeated thermal exposure to 260°C soldering conditions. The modified solder mask showed zero peeling or blistering after 5 reflow cycles, meeting automotive IPC-4101C /21 requirements while maintaining excellent resolution for fine-pitch component applications.

 Case 4: 3C Product Hard Coat

A consumer electronics surface treatment company developed a UV-curable hard coating for smartphone and tablet displays using CS-697 as a key adhesion promoter. The coating formulation containing 1.5% CS-697 achieved 5H pencil hardness on polycarbonate substrates with excellent cross-hatch adhesion (5B rating). The multi-functional epoxy groups enabled strong bonding to both the polycarbonate substrate and the silica nanoparticles in the coating, providing scratch resistance without compromising optical clarity.

Application Case 5: Electronic Potting Compound for Power Electronics

A power electronics manufacturer reformulated their epoxy potting compound for IGBT modules by adding CS-697 as an interfacial modifier. The coupling agent improved adhesion between the potting compound and diverse substrate materials including ceramics, copper, and aluminum. Thermal cycling reliability tests (-55°C to 125°C, 2000 cycles) showed no interfacial cracking or debonding, significantly extending the operational lifetime of the power modules in demanding industrial applications.