Dow Dowsil 3-6121 Low Temperature Elastomer

Dow Dowsil 3-6121 Low Temperature Elastomer Datasheet
  • Description for Dow Dowsil 3-6121 Low Temperature Elastomer

    Two part; 10:1 mix; minimal shrinkage; no exotherm during cure; no solvents or cure byproducts; deep section cure; repairable; good dielectric properties; flexible elastomer.

    *See Terms of Use Below

    Brand Dowsil
    Application Type Pot, Encapsulate
    1 Part or 2 Part 2 Part
    Material Form Liquid, Silicone elastomer
    Industry Electronics, Optical applications requiring high refractive index, PCB system applications, E-Mobility Solutions, Smart Meters, Electrical applications
    Manufacturer Dow
    Chemistry Silicone elastomer, Solvent-free
    Cure Method 2-Part Cure, Heat
    Cure Temperature (°C) 100, 150, 125
    Cure Time (min) 20, 10, 20
    Viscosity (cPs) 19,250, Flowable
    Color Translucent
    Ozone Resistance Ozone resistance
    Chemical Resistance Good
    High Temperature Resistance (°C) 200
    Low Temperature Resistance (°C) -45, -55, -65
    Light Refractive Index (RI) Higher
  • Technical Data for Dow Dowsil 3-6121 Low Temperature Elastomer

    Overview
    • Application Type
    • 1 Part or 2 Part
      • 1 Part or 2 Part - 2 Part
      • Part A Name - Base
      • Part B Name - Curing Agent
    • Material Form
      • Elastomer - Silicone elastomer
      • Liquid
    • Industry
      • Optical - Optical applications requiring high refractive index
      • E-Mobility Solutions
      • Electronics - Electrical applications
      • Printed Circuit Board (PCB) - PCB system applications
      • Smart Meters
      • Industrial - Low-temperature encapsulating applications
    • Chemistry
    • Application Method
      • Dispenser - Automated metered mixing and dispensing
    • Cure Method
      • Heat
      • 2-Part Cure
    • Color
      • Translucent
    • Brand
      • Dowsil
    Specifications
    Cure Specs
    Cure Temperature (°C) 100, 150, 125 Test Method
    Cure Time (min) 20, 10, 20 Test Method
    Viscosity (cPs) 19,250, Flowable Test Method
    Linear Shrinkage (%) Minimal shrinkage
    Work / Pot Time (min) >120 Test Method
    Mix Ratio 10:1 (by volume), 10:1 (by weight)
    Bond Strength
    General Bond Strength (psi) Good
    Tear Strength (piw) High, 60 (ppi) Test Method
    Tensile Strength (psi) High, 625
    Material Resistance
    Ozone Resistance Ozone resistance
    Chemical Resistance Good
    UV Resistance UV resistance
    Environmental Resistance Environmental resistance
    High Temperature Resistance (°C) 200
    Low Temperature Resistance (°C) -45, -55, -65
    Moisture/Humidity Resistance Moisture/humidity resistance
    Conductivity
    Dissipation Factor 0.01000, <0.00100 Test Method
    Dielectric Strength (V/mil) Good, Durable, 450
    Dielectric Constant 2.92, 2.92 Test Method
    Thermal Conductivity (W/m°K) 0.18, 0.18
    Volume Resistivity (O) 4.15 E+14 (ohms/cm)
    Hardness
    Shore A Hardness 34 Test Method
    Elongation (%) 275
    Flexibility Flexible
    Other Properties
    Light Refractive Index (RI) Higher
    Specific Gravity 1.120 Test Method
    Coefficient of Thermal Expansion (CTE) 290 (Linear (micron/m °C or ppm ))
    Business Information
    Shelf Life Details Shelf life is indicated by the “Use Before” date found on the product label. For best results, Dow silicone encapsulants should be stored at or below 25°C (77°F). Special precautions must be taken to prevent moisture from contacting these materials. Containers should be kept tightly closed and head or air space minimized. Partially filled containers should be purged with dry air or other gases, such as nitrogen.
    Shelf Life Temperature (°F) 77
    Shelf Life (mon) 18
    Not Good For
    Don't Use For Organotin and other organometallic compounds, Silicone rubber containing organotin catalyst, Sulfur, Polysulfides, Polysulfones, Other sulfur containing materials, Unsaturated hydrocarbon plasitcizers, Some solder flux residues
  • Best Practices for Dow Dowsil 3-6121 Low Temperature Elastomer

    *See Terms of Use Below

    1. Surface Preparation

      Standard silicone encapsulants require a surface treatment with a primer in addition to good cleaning for adhesion while primerless silicone encapsulants require only good cleaning.

      In applications requiring adhesion, priming will be required for the silicone encapsulants. See the Primer Selection Guide for the correct primer to use with a given product. For best results, the primer should be applied in a very thin, uniform coating and then wiped off after application. After application, it should be thoroughly air dried prior to application of the silicone elastomer. Additional instructions for primer usage can be found in the information sheets specific to the individual primers.

    2. Mixing

      Dow silicone encapsulants are supplied as two-part liquid component kits. When liquid components are thoroughly mixed, the mixture cures to a flexible elastomer, which is well suited for the protection of electrical/PCB system applications. The 10:1 mix ratio gives one latitude to tune the modulus and hardness for specific application needs and production lines.

    3. Curing

      Dow silicone encapsulants cure without exotherm at a constant rate regardless of sectional thickness or degree of confinement. Dow silicone elastomers require no post cure and can be placed in service immediately following the completion of the cure schedule.

      Thoroughly mixed Dow silicone encapsulant may be poured/dispensed directly into the container in which it is to be cured. Care should be taken to minimize air entrapment. When practical, pouring/dispensing should be done under vacuum, particularly if the component being potted or encapsulated has many small voids. If this technique cannot be used, the unit should be evacuated after the silicone encapsulant has been poured/dispensed. Dow silicone encapsulants may be either room temperature (25°C/77°F) or heat cured. Room temperature cure encapsulants may also be heat accelerated for faster cure. Ideal cure conditions for each product are given in the product selection table. Two part condensation cure encapsulants should not be heat accelerated above 60°C (140°F).

      Cure reaction begins with the mixing process. Initially, cure is evidenced by a gradual increase in viscosity, followed by gelation and conversion to a solid elastomer.

      Certain materials, chemicals, curing agents and plasticizers can inhibit the cure of addition cure adhesives. Most notable of these include: organotin and other organometallic compounds, silicone rubber containing organotin catalyst, sulfur, polysulfides, polysulfones or other sulfur containing materials, unsaturated hydrocarbon plasitcizers, and some solder flux residues. If a substrate or material is questionable with respect to potentially causing inhibition of cure, it is recommended that a small scale compatibility test be run to ascertain suitability in a given application. The presence of liquid or uncured product at the interface between the questionable substrate and the cured gel indicates incompatibility and inhibition of cure.

    4. Removal

      In the manufacture of electrical/PCB system assemblies it is often desirable to salvage or reclaim damaged or defective units. With most non-silicone rigid potting/encapsulating materials, removal or entry is difficult or impossible without causing excessive damage to internal circuitry. Dow silicone encapsulants can be selectively removed with relative ease, any repairs or changes accomplished, and the repaired area repotted in place with additional product. To remove silicone elastomers, simply cut with a sharp blade or knife and tear and remove unwanted material from the area to be repaired.

      Sections of the adhered elastomer are best removed from substrates and circuitry by mechanical action such as scraping or rubbing and can be assisted by applying Dow brand OS Fluids. Before applying additional encapsulant to a repaired device, roughen the exposed surfaces of the cured encapsulant with an abrasive paper and rinse with a suitable solvent. This will enhance adhesion and permit the repaired material to become an integral matrix with the existing encapsulant. Silicone prime coats are not recommended for adhering products to themselves.

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Cure Temperature Test Methods
Cure Temperature Cure Time Test Method
100°C Heat Cure
150°C Heat Cure
125°C Heat Cure
Cure Time Test Methods
Cure Time Test Method
20 min Heat Cure
10 min Heat Cure
20 min Heat Cure
Viscosity Test Methods
Viscosity Test Method
19,250 cPs Mixed
Flowable
Work / Pot Time Test Methods
Work / Pot Time Test Method Temperature
>120 min Pot life 25°C
Tear Strength Test Methods
Tear Strength Test Method
High
60 (ppi) Die B
Dielectric Constant Test Methods
Dielectric Constant Test Method
2.92 Dielectric constant, 100 Hz
2.92 Dielectric constant, 100 KHz
Dissipation Factor Test Methods
Dissipation Factor Test Method
0.01000 Dissipation factor, 100 Hz
<0.00100 Dissipation factor, 100 KHz
Shore A Hardness Test Methods
Shore A Hardness Shore Hardness Test Method
34 Durometer
Specific Gravity Test Methods
Specific Gravity Test Method
1.120 Cured