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Description for Dow Dowsil 3-6635 Dielectric Gel
Extremely soft to medium hardness, thermal/mechanical shock and vibration damping, excellent dielectric properties, flexible cure schedule, reversion resistant, thick section cure, compatible with automated dispensing equipment, and physical and electrical stability over a wider temperature range than the other types of gels.Brand Dowsil Application Type Encapsulants 1 Part or 2 Part 1-Part Material Form Gel Industry Optoelectronics, PCB system assemblies, Smart Meters, E-Mobility Solutions, Smart Home Devices Manufacturer Dow Chemistry Silicone Cure Method Heat Cure Temperature (°C) 100, 125, 150, 100 Cure Time (min) 48, 7, 6, 120 Viscosity (cPs) Low, 700 Color Clear High Temperature Resistance (°C) 200 Low Temperature Resistance (°C) -45, -55 Volume Resistivity (O) 4.8E+13 (ohms/cm) Light Refractive Index (RI) High -
Technical Data for Dow Dowsil 3-6635 Dielectric Gel
Overview
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Application Type
- Pottant / Encapsulant - Encapsulants
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1 Part or 2 Part
- 1-Part
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Material Form
- Gel
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Industry
- Smart Meters
- Smart Home Devices
- E-Mobility Solutions
- Electronics - Optoelectronics
- Printed Circuit Board (PCB) - PCB system assemblies
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Chemistry
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Application Method
- Other - Manual or automated equipment
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Cure Method
- Heat
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Color
- Clear / Transparent - Clear
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Brand
- Dowsil
Specifications
Cure Specs
Cure Temperature (°C) 100, 125, 150, 100 Test Method Cure Time (min) 48, 7, 6, 120 Test Method Viscosity (cPs) Low, 700 Set Time (min) 11 Test Method Material Resistance
High Temperature Resistance (°C) 200 Low Temperature Resistance (°C) -45, -55 Moisture/Humidity Resistance Moisture/humidity resistance Conductivity
Dissipation Factor 0.00020, <0.00010 Test Method Dielectric Strength (V/mil) 525, Excellent Dielectric Constant 2.83, 2.84 Test Method Volume Resistivity (O) 4.8E+13 (ohms/cm) Hardness
Shore A Hardness 75 g, Soft to Medium Flexibility Resilient, Flexible Other Properties
Light Refractive Index (RI) High Specific Gravity 1.000 Test Method Flash Point (°F) 231.8 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) 6 Not Good For
Don't Use For Other sulfur containing materials, Polysulfones, Polysulfides, Sulfur, Silicone rubber containing organotin catalyst, Organometallic compounds, Organotin compounds, Unsaturated hydrocarbon plasitcizers, Some solder flux residues -
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Best Practices for Dow Dowsil 3-6635 Dielectric Gel
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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.
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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 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.
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Curing
Working time (or pot life) is the time required for the initial mixed viscosity to double at room temperature (RT). For one-part products the viscosity either increases at a much lower rate or does not change significantly at RT. 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. 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.
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Testing
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 |
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100°C | Rheometer T90 Cure Time |
125°C | Rheometer T90 Cure Time |
150°C | Rheometer T90 Cure Time |
100°C | Heat Cure |
Cure Time Test Methods
Cure Time | Test Method |
---|---|
48 min | Rheometer T90 Cure Time |
7 min | Rheometer T90 Cure Time |
6 min | Rheometer T90 Cure Time |
120 min | Heat Cure |
Set Time Test Methods
Set Time | Set Temperature | Test Method |
---|---|---|
11 min | 135°C | Gel Time |
Dielectric Constant Test Methods
Dielectric Constant | Test Method |
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2.83 | 100 Hz |
2.84 | 100 kHz |
Dissipation Factor Test Methods
Dissipation Factor | Test Method |
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0.00020 | 100 hz |
<0.00010 | 100 kHz |
Specific Gravity Test Methods
Specific Gravity | Test Method |
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1.000 | Uncured |