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, 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
1 Part or 2 Part
- 1 Part or 2 Part - 2 Part
- 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
- Industrial - Delicate components
- Dispenser - Automated dispensing equipment
- Room Temperature / Air Dry - Room temperature cure
- 2-Part Cure
- Clear / Transparent - Clear
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
High Temperature Resistance (°C) 200 Low Temperature Resistance (°C) -45, -55
Dielectric Strength (V/mil) Excellent, 450 Volume Resistivity (O) 4.6E+15 (ohms/cm)
Dimensional Stability Dimensional stability of an elastomer Flexibility Flexible, Resilient, Soft
Light Refractive Index (RI) High Specific Gravity 0.970 Test Method
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
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.
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.
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.
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|
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.|