Dow Dowsil 3-4118 Gel

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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.

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Brand	Dowsil
Application Type	Coating, Encapsulating , Seal, Potting
1 Part or 2 Part	2-Part
Material Form	Gel
Industry	Optoelectronics, Various PCB system assemblies, Smart Meters, E-Mobility Solutions, 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, Heat, Room temperature cure
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
Volume Resistivity (O)	4.6E+15 (ohms/cm)
Light Refractive Index (RI)	High

Best Practices for Dow Dowsil 3-4118 Gel

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Technical Data for Dow Dowsil 3-4118 Gel

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Overview

Application Type
- Coating
- Pottant / Encapsulant - Encapsulating , Potting
- Sealant - Seal
1 Part or 2 Part
- 2-Part
Material Form
- Gel
Industry
- Smart Meters
- Smart Home Devices
- 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
- Industrial - Delicate components
Chemistry
- Silicone
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

Dimensional Stability (%)	Dimensional stability of an elastomer
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

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.
Comparable Materials for Dow Dowsil 3-4118 Gel

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Spec Engine^® Results
- Dowsil 3-4154 Dielectric Gel(Dow)
  Extremely soft or firm, 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 wide temperature range.
- Dowsil 3-4133 Dielectric Gel(Dow)
  Long working time at RT and low viscosity provide processing flexibility and Fast heat cure for increased processing speeds.
- Dowsil EG-4230 Black Gel(Dow)
  ▪ Two-part ▪ 1:1 mix ratio ▪ Fast Room temperature cure ▪ Flowable ▪ Black ▪ Polydimethylsiloxane gel
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