Dow Dowsil 3-4154 Dielectric Gel
Brand Dowsil Application Type Coating, Potting , Encapsulating 1 Part or 2 Part 2 Part Material Form Gel Industry Optoelectronics, Various PCB systems assemblies, Smart Meters, E-Mobility Solutions, Smart Home Devices, Insulation, Headlamp assemblies Manufacturer Dow Chemistry Silicone Cure Method 2- Part Cure, Heat cure, Room Temperature Cure Temperature (°C) 100, 80 Cure Time (min) 105, 180, Fast Viscosity (cPs) 550 Color Clear High Temperature Resistance (°C) 200 Low Temperature Resistance (°C) -45, -55 Light Refractive Index (RI) High
Best Practices for Dow Dowsil 3-4154 Dielectric 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.
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, a small-scale compatibility test should 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. In certain situations, toughened gels may appear fully cured but have reduced or no adhesion. This may result from slight inhibition at the interface.
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Cure Temperature Test Methods
|Cure Temperature||Cure Time Test Method|
Cure Time Test Methods
|Cure Time||Test Method|
|105 min||Heat Cure|
|180 min||Heat Cure|
Viscosity Test Methods
Work / Pot Time Test Methods
|Work / Pot Time||Test Method||Temperature|
|30 min||(Pot Life - hours)||25°C|
Dielectric Constant Test Methods
|Dielectric Constant||Test Method|
|2.87||Dielectric constant, 100 Hz|
|2.87||Dielectric constant, 100 KHz|
Dissipation Factor Test Methods
|Dissipation Factor||Test Method|
|0.00300||Dissipation factor, 100 Hz|
|0.00010||Dissipation factor, 100 KHz|
Specific Gravity Test Methods
|Specific Gravity||Test Method|