DOWSIL EG-4131
Harmonization Code : 3907.30.00.40 | Epoxy Mold Compounds containing by weight more than 70 % silicon dioxide
Main features
- Clear 1:1 Pdms Dielectric Gel
- 650 cP Mixed Viscosity
- 91.1% Transmission at 450 Nm
Product Description
DOWSIL EG-4131 Dielectric Gel Kit is a two-part, colorless, flowable PDMS gel that can cure at room temperature or with added heat. It can be used for liquid optical clear coupling in display and LED lighting applications and for coating, encapsulating or potting PCB assemblies where a soft protective gel is required. Documented applications include display optical coupling, led lighting, and pcb coating, encapsulation and potting. The matched-viscosity components can be mixed manually for low-volume work or with static or dynamic meter-mix equipment for higher-volume processes.
Key features
- Flow and dispensing: Clear 1:1 PDMS gel with 650 cP mixed viscosity for flowable dispensing.
- Key characteristic: 91.1% transmission at 450 nm through 3.2 mm with a refractive index of 1.41 at 632.8 nm.
- Processing window: 30-minute working time at 25 C with room-temperature or heat-accelerated cure.
Applications
- Display optical coupling
- LED lighting
- PCB coating, encapsulation and potting
TDS, SDS & Technical Documents
Technical Specifications
General Properties
Mechanical Properties
Electrical Properties
Additional Information
Potting, Encapsulants & Underfills
Clear 1:1 dielectric gel for optical coupling and electronic protection
DOWSIL EG-4131 Dielectric Gel Kit is a two-part, colorless, flowable PDMS gel that can cure at room temperature or with added heat. It can be used for liquid optical clear coupling in display and LED lighting applications and for coating, encapsulating or potting PCB assemblies where a soft protective gel is required.
As-Supplied Properties
Flowable 1:1 gel properties
Component and mixed viscosities are separated from cured and optical properties. Values are typical and condition-specific.
| Property | Typical Value | State / Condition |
|---|---|---|
| Color | Colorless | As supplied |
| Part A viscosity | 750 cP (0.75 Pa-s) | As supplied |
| Part B viscosity | 650 cP (0.65 Pa-s) | As supplied |
| Mixed viscosity | 650 cP (0.65 Pa-s) | Mixed |
| Mix ratio | 1:1 | Part A : Part B |
| Working time / pot life | 30 minutes | 25 deg C |
Working time is the time required for the initial mixed viscosity to double at room temperature.
Processing
Meter mixing, de-airing and temperature-controlled cure
The matched-viscosity components can be mixed manually for low-volume work or with static or dynamic meter-mix equipment for higher-volume processes.
- Meter Part A and Part B at the 1:1 ratio and mix thoroughly.
- Design the mixing and dispensing process to minimize entrapped air.
- When needed, vacuum de-air at greater than 28 in. Hg to remove incorporated gas.
- Use room-temperature cure or add heat to accelerate the cure reaction.
Tack-free time at 4 mm
- 80 minutes at 25 deg C.
- <=10 minutes at 50 deg C.
- <=5 minutes at 100 deg C.
- <=5 minutes at 150 deg C.
Allow additional time for the part to heat toward oven temperature and verify the cure schedule in the intended assembly.
Storage and Handling
Keep components dry and tightly closed
Shelf life and storage temperature are identified on the product label. Moisture exposure should be minimized during storage and dispensing.
- Keep containers tightly closed and minimize headspace.
- Purge partially filled containers with dry air or nitrogen when needed.
- Moisture exposure can reduce adhesion and contribute to bubble formation.
- The product is generally supplied in batch-matched kits containing Part A and Part B.
Technical Guidance
Control air entrapment and cure inhibition
Two process controls are particularly important for addition-cure dielectric gels: minimizing entrained gas and checking materials that may inhibit cure.
Air management
Avoid applying air pressure directly to an exposed liquid gel surface. Bladder packaging, careful mixing and vacuum de-airing can reduce incorporated air before cure.
Compatibility screening
Organotin and other organometallic compounds, sulfur-containing materials, unsaturated hydrocarbon plasticizers and some solder flux residues can inhibit cure. Run a small-scale compatibility test when a material is questionable.
Repair and rework
For PCB assemblies, the gel can be removed to access components. After repair, clean and dry the area before patching with additional silicone gel.
Final-State Properties
Cured, optical and electrical properties
Preserve specimen thickness, wavelength and test configuration when using optical or electrical data.
| Property | Typical Value | Method / Condition |
|---|---|---|
| Specific gravity | 0.97 | Cured |
| Gel hardness | 730 g | Cured |
| Elongation | 175% | Cured |
| Unprimed lap shear adhesion | 80 psi (0.55 MPa) | Glass / glass |
| Linear CTE | 460 ppm/ deg C | By DMA |
| Refractive index | 1.41 | 632.8 nm |
| Transmission | 89.4% / 91.1% / 93.3% | 380 / 450 / 760 nm, 3.2 mm |
| Dielectric strength | 13.7 V/mil (0.54 kV/mm) | Cured |
| Volume resistivity | 6.32 x 1013ohm-cm | Cured |
These values are typical and are not specification values.
Applications
Optical coupling and protective gel applications
DOWSIL EG-4131 combines a clear optical path with the soft, resilient behavior of a cured silicone gel.
Display optical coupling
Use as a liquid optically clear coupling material where the refractive index and transmission profile match the assembly requirements.
LED lighting
The product is specifically listed for LED lighting optical-coupling applications.
PCB coating, encapsulation and potting
The gel can be used for coating, encapsulating or potting PCB assemblies, including assemblies with delicate components.
Review optical, cure and dispensing requirements
Krayden can help compare the 1:1 mixing process, optical transmission, refractive index, working time, cure temperature and de-airing requirements of DOWSIL EG-4131 against your display, LED or electronic assembly. Krayden can also help review the documented processing conditions and evaluation criteria before testing.
