Dow Dowsil 3-4118 Gel

Dow Dowsil 3-4118 Gel Datasheet
  • Description for Dow Dowsil 3-4118 Gel

    A two-part, soft, clear gel, 1:1 mix ratio, high viscosity to limit flow out. These gels have been used extensively to seal and protect by coating, encapsulating or potting various PCB system assemblies, especially those with delicate components.

    *See Terms of Use Below

    Brand Dowsil
    Application Type Encapsulating , Coating, Seal, Potting
    1 Part or 2 Part 2 Part
    Material Form Gel
    Industry Optoelectronics, Various PCB system assemblies, E-Mobility Solutions, Smart Meters, Smart Home Devices, Isolate circuits from the harmful effects of other contaminants, Isolate circuits from the harmful effects of moisture, Electrical insulation for high voltages, Protect circuits from thermal and mechanical stresses, Protect interconnections from thermal and mechanical stresses
    Manufacturer Dow
    Chemistry Silicone
    Cure Method 2-Part Cure, Room temperature cure, Heat
    Cure Temperature (°C) 20 to 25, 125
    Cure Time (min) 60
    Viscosity (cPs) High
    Color Clear
    High Temperature Resistance (°C) 200
    Low Temperature Resistance (°C) -45, -55
    Light Refractive Index (RI) High
  • Technical Data for Dow Dowsil 3-4118 Gel

    Overview
    • Application Type
    • 1 Part or 2 Part
      • 1 Part or 2 Part - 2 Part
    • Material Form
      • Gel
    • Industry
      • E-Mobility Solutions
      • Electronics - Optoelectronics, Isolate circuits from the harmful effects of other contaminants, Isolate circuits from the harmful effects of moisture, Electrical insulation for high voltages, Protect circuits from thermal and mechanical stresses, Protect interconnections from thermal and mechanical stresses
      • Printed Circuit Board (PCB) - Various PCB system assemblies
      • Smart Meters
      • Smart Home Devices
      • Industrial - Delicate components
    • Chemistry
    • Application Method
      • Dispenser - Automated dispensing equipment
    • Cure Method
      • Room Temperature / Air Dry - Room temperature cure
      • Heat
      • 2-Part Cure
    • Color
      • Clear / Transparent - Clear
    • Brand
      • Dowsil
    Specifications
    Cure Specs
    Cure Temperature (°C) 20 to 25, 125 Test Method
    Cure Time (min) 60 Test Method
    Viscosity (cPs) High
    Work / Pot Time (min) 30 Test Method
    Mix Ratio 1:1
    Material Resistance
    High Temperature Resistance (°C) 200
    Low Temperature Resistance (°C) -45, -55
    Conductivity
    Dielectric Strength (V/mil) Excellent, 450
    Volume Resistivity (O) 4.6E+15 (ohms/cm)
    Hardness
    Dimensional Stability Dimensional stability of an elastomer
    Flexibility Flexible, Resilient, Soft
    Other Properties
    Light Refractive Index (RI) High
    Specific Gravity 0.970 Test Method
    Business Information
    Shelf Life Details Storage conditions and shelf life (“Use By” date) are indicated on the product label.
    Shelf Life Temperature (°F) 77
    Shelf Life (mon) 12
    Not Good For
    Don't Use With Some solder flux residues, Unsaturated hydrocarbon plasitcizers, Organotin compounds, Organometallic compounds, Silicone rubber containing organotin catalyst, Sulfur, Polysulfides, Polysulfones , Other sulfur containing materials
  • Best Practices for Dow Dowsil 3-4118 Gel

    *See Terms of Use Below

    1. Mixing

      Some gels are supplied in bladder packs that avoid direct air contact with the liquid gel components, allowing use of air pressure over the pack in a pressure pot for dispensing. Do not apply air pressure directly to the liquid gel surface (without the bladder pack) as the gel can become supersaturated with air and bubbling can occur when the material is dispensed and cured. Use of bladder packs prevents bubbling, maintains cleanliness and avoids gel contamination. Gels can be dispensed manually or by using one of the available types of meter mix equipment. Typically, the two components are of matched viscosities and are readily mixed with static or dynamic mixers, with automated meter-mix normally used for high volume processes. For low volume applications, manual weighing and simple hand mixing may be appropriate. Inaccurate proportioning or inadequate mixing may cause localized or widespread problems affecting the gel properties or cure characteristics.

    2. Deairing/Degassing

      If possible, the potential for entrapment and incorporation of gas (typically air) should be considered during design of the part and selection of a process to mix and dispense the gel. This is especially important with higher viscosity and faster-curing gels. Degassing at > 28 inches (10–20 mm) Hg vacuum may be necessary to ensure a void-free, protective layer.

    3. Curing

      Working time (or pot life) is the time required for the initial mixed viscosity to double at room temperature (RT). The cure reaction begins when Parts A and B are mixed. As the cure progresses, viscosity increases until the material becomes a soft gel. Cure conditions are shown in the typical properties table. Cure is defined as the time required for a specific gel to reach 90% of its final properties. Gels will reach a no-flow state prior to full cure. Additioncure silicone gels may be RT and heat cure or exclusively heat cure. Adding heat accelerates the cure reaction. Additional time should be allowed for heating the part to near oven temperature. Cure schedules should be verified in each new application.

      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. Testing

      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.

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Cure Temperature Test Methods
Cure Temperature Cure Time Test Method
20 to 25°C
125°C Heat Cure
Cure Time Test Methods
Cure Time Test Method
60 min Heat Cure
Work / Pot Time Test Methods
Work / Pot Time Test Method Temperature
30 min Pot Life 25°C
Specific Gravity Test Methods
Specific Gravity Test Method
0.970 Cured or uncured A & B.