RTV160, RTV162 and RTV167 adhesive sealants from Momentive Performance Materials are one-component, ready-to-use electronic grade silicone sealants. They cure to a tough, resilient silicone rubber on exposure to atmospheric moisture at room temperature. These electronic-grade silicone adhesive sealants differ somewhat in physical properties including consistency.
RTV160, RTV162 and RTV167 are recommended for use in aerospace, automotive, appliance and other industries which incorporate electronic components into a finished product. Electronic and integrated circuits, semiconductors and copper connections are typical applications.
RTV160 adhesive sealant is recommended for insulating, encapsulating and coating in thin sections [less than 6mm (1/4")], where flow into small crevices or hard-to-reach places is desired.
RTV162 adhesive sealant is recommended for sealing and bonding of electronic components onto printed circuit boards and protecting copper connections on electronic parts assemblies.
RTV167 adhesive sealant is recommended for sealing and bonding where high strength would be required.
RTV160, RTV162 and RTV167 adhesive sealants will bond to many clean surfaces without the aid of primers. These surfaces normally include many metals, glass, ceramic, silicone rubber and some rigid plastics. These adhesive sealants will also bond to some organic rubbers and flexible plastics not containing fugitive plasticizers (those that migrate to the surface impairing adhesion). An evaluation should be made to determine bond strength for each specific application.
For difficult-to-bond substrates, use of a primer is suggested. SS4004, SS4044 and SS4179 primers are recommended for use with RTV160, RTV162 and RTV167 sealants. Complete information and usage instructions for these primer products are contained in a separate product data sheet.
Where adhesion is required, surfaces should be thoroughly cleaned with a suitable solvent to remove dirt, oil and grease. The surface should be dry before applying the adhesive sealant.
When solvents are used, proper safety precautions must be observed.
Cure Time Cycle
RTV160, RTV162 and RTV167 adhesive sealants may be applied directly to a clean or primed substrate. The adhesive sealant begins to cure on exposure to moisture in the air at room temperature. Where broad surfaces are to be bonded the sealant should be applied in a thin, less than 6mm (¼ in.) diameter bead or ribbon around the edge of one of the surfaces.
The cure process begins with the formation of a skin on the exposed surface of the sealant and progresses inward through the material. At 25°C (77°F) and 50% relative humidity, these products will form a surface skin which is tack-free to the touch in about 4 hours. Once the tack-free skin has begun to form, further tooling of the adhesive sealant is not advisable.
High temperatures and high humidity will accelerate the cure process low temperatures and low humidity will slow the cure rate.
As the adhesive sealant cures, alcohol vapors are released from the sealant surface. This by-product of cure has a slight, but non-objectionable odor which will completely disappear after curing is completed.
A 3mm (1/8 in.) section of adhesive sealant will cure through in approximately 48 hours at 25°C (77°F) and 50% relative humidity. Since cure time increases with thickness, use of RTV160, RTV162 and RTV167 sealants should be limited to section thicknesses of 6mm (¼ in.) or less.
PACKAGING AND DISPENSING
RTV160, RTV162, RTV167 adhesive sealants are supplied in caulking cartridges and bulk containers. RTV162 and RTV167 are also available in collapsible squeeze tubes.
Tubes may be squeezed by hand or with the aid of mechanical wringers which allow more complete removal of material from the tube. The sealant may be dispensed from caulking cartridges by using simple mechanical caulking guns or air-operated guns. Air-operated guns will allow greater control and application speed. Both tubes and cartridges are easy to use, can be put into production quickly and require minimum capital investment.
Note: Do not exceed 45 psig when used in air-powered caulking guns.Bulk containers offer the most economical packaging for volume production.
Bulk dispensing systems are air-operated extrusion pumps coupled to hand or automated dispensing units.
Recommendations for pump selection and assistance in converting lines from other silicone systems to the RTV160, RTV162 and RTV167 alkoxy cure system sealants are available from Momentive Performance Materials.
CLEAN UP AND REMOVAL
Before cure, solvent systems such as naphtha or methyl ethyl ketone (MEK) are effective.
RTV162 and RTV167 sealants meet the physical requirements of MIL-A-46146. Testing is performed in accordance with current Momentive Performance Materials quality test methods, laboratory conditions, and procedures, frequency and sampling, which are not necessarily identical with the methods, conditions, procedures, frequency and sampling stated or referenced in MIL-A-46146. Any certification will be limited to listed properties and will not imply or state conformity to any other aspect of MIL-A-46146, including but not limited to marking, packaging, bar coding, testing, or sampling. Contact Momentive Performance Materials for a comparison review.