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EPM Electronic Packaging Material - Silicone

 

EPM Electronic Packaging Material Product Listing

EPM-2401 » Low Volatility Thermal Interface Silicone Grease

PROPERTIES
Typical PropertiesAverage Result
Appearance*White
Specific Gravity*2.3
Thermal Conductivity0.70 W/mK(17x 10-4 cal/(cm sec*C))
Dielectric Strength13 kV at 0.1 in. spacing (13kV at 2.5 mm spacing)
Dielectric Constant4.2 at 1 kHz
Volatile Content (1 hour at 300°C)0.23%
Ionic Content, Cl< 5 ppm
Ionic Content, K< 2 ppm
Ionic Content, Na<4 ppm

*Properties tested on a lot-to-lot basis. Do not use the properties shown in this technical profile as a basis for preparing specifications. Pleasecontact NuSil Technology for assistance and recommendations in establishing particular specifications.


EPM-2410 » Low Volatility Silicone Elastomer

PROPERTIES
Typical PropertiesAverage Result
Uncured:
AppearanceTranslucent
Viscosity, Part A62,000 cP (62,000 mPas)
Viscosity, Part B40,000 cP (40,000 mPas)
Work Time30 minutes
Cured: 15 minutes at 150°C (302°F)
Durometer, Type A30
Tensile Strength750 psi (5.2 MPa)
Elongation350%
Lap Shear Strength400 psi (2.8 MPa)
Volatile Content (1 hour at 275°C)0.5%
Moisture Absorption0.07%
Volume Resistivity1.0 X Ohm 10exp13 cm
Dielectric Strength580 V/mil (22.62 kV/mm)
Dielectric Constant, 100 Hz2.9
Dielectric Constant, 1 kHz2.9
Loss Tangent, 100 Hz0.0003
Loss Tangent, 1 kHz0.0003
Coefficient of Linear Expansion28 µm/(m°C)
Glass Transition Temperature (Tg) (-70°C to 200°C)-117°C (-178.6°F)
Ionic Content, Na< 6 ppm
Ionic Content, K< 3 ppm
Ionic Content, Cl< 6 ppm

The above properties are tested on a lot-to-lot basis. Do not use as a basis for preparing specifications. Please contact NuSil Technology for assistance and recommendations in establishing particular specifications.


EPM-2410-1 » Low Volatility Potting And Encapsulating Silicone Adhesive

PROPERTIES
Typical PropertiesAverage Result
Uncured:
Appearance*White
Viscosity, Part A*60,000 cP (60,000 mPas)
Viscosity, Part B*40,000 cP (40,000 mPas)
Work Time*30 minutes
Tack-Free Time*4 hours
Cured: 15 minutes at 150°C (302°F)
Durometer, Type A*30
Tensile Strength*700 psi (4.8 MPa)
Elongation*350%
Lap Shear Strength* (primed w/ CF1-135)400 psi (2.8 MPa)
Coefficient of Linear Thermal Expansion
Below Tg (-150°C to -115°C)60 ppm/°C (60µm/m/°C)
Above Tg (-95°C to 250°C)445 ppm/°C (445µm/m/°C)
Volatile Content (1 hour at 275°C)0.5%
Thermal Conductivity0.230 W/(mK)(55 x 10-5 cal/(cm sec°C))
Dynamic Mechanical Analysis (DMA)See Profile PDF for Graph
Ionic Content, Cl< 15 ppm
Ionic Content, K< 1 ppm
Ionic Content, Na< 2 ppm

*Properties tested on a lot-to-lot basis. Do not use the properties shown in this technical profile as a basis for preparing specifications. Please contact NuSil Technology for assistance and recommendations in establishing particular specifications.


EPM-2410-2 » Low Volatility Silicone Adhesive

PROPERTIES
Typical PropertiesAverage Result
Uncured:
Appearance*Black
Viscosity, Part A*65,000 cP (65,000 mPas)
Viscosity, Part B*40,000 cP (40,000 mPas)
Work Time*30 minutes
Tack-Free Time* (at 65°C)5 hours
Cured: 15 minutes at 150°C (302°F)
Durometer, Type A*30
Tensile Strength*750 psi (5.2 MPa)
Elongation*400%
Lap Shear Strength* (primed w/ CF1-135)425 psi (2.9 MPa)
Volatile Content (1 hour at 275°C)0.6%
Ionic Content, Cl< 5 ppm
Ionic Content, K< 1 ppm
Ionic Content, Na< 1 ppm

*Properties tested on a lot-to-lot basis. Do not use the properties shown in this technical profile as a basis for preparing specifications. Please contact NuSil Technology for assistance and recommendations in establishing particular specifications.


EPM-2411-2 » Low Volatility Silicone Glob-Top

PROPERTIES
Typical PropertiesAverage Result
Uncured:
Appearance*Black
Viscosity*300,000 cP (300,000 mPas)
Extrusion Rate* (Performed using 14 gauge, 1.5 inch metal tip and 30 psi)0.9 g/min
Cured: 15 minutes at 200°C (392°F)
Specific Gravity*1.15
Durometer, Type A*20
Tensile Strength*750 psi (5.2 MPa)
Elongation*700%
Tear Strength*50 ppi (8.8 kN/m)
Rheometer (ODR) Maximum Torque*30 in-lbs
Rheometer (ODR) Scorch Time*2.5 minutes
Volume Resistivity1 x 1015 ohm cm
Dielectric Constant at 100Hz3.1
Dissipation Factor at 100 Hz0.001

*Properties tested on a lot-to-lot basis. Do not use the properties shown in this technical profile as a basis for preparing specifications. Please contact NuSil Technology for assistance and recommendations in establishing particular specifications.


EPM-2420 » Low Volatility General Purpose Silicone Adhesive

PROPERTIES
Typical PropertiesAverage Result
Uncured:
Appearance*Transparent
Viscosity, Mixed*2,600 cP (2,600 mPas)
Cured: 1 hour at 65°C (149°F)
Specific Gravity*1.01
Durometer, Type A*30
Tensile Strength*425 psi (2.9 MPa)
Elongation*150%
Volatile Content (1 hour at 275°C)0.85%
Ionic Content, Cl<2 ppm
Ionic Content, K<1 ppm
Ionic Content, Na<8 ppm

*Properties tested on a lot-to-lot basis. Do not use the properties shown in this technical profile as a basis for preparing specifications. Please contact NuSil Technology for assistance and recommendations in establishing particular specifications.


EPM-2421 » Low Volatility Silicone Elastomer

PROPERTIES
Typical PropertiesAverage Result
Uncured:
AppearanceTransparent
Viscosity, Part A3,750 cP (3,750 mPas)
Viscosity, Part B2,700 cP (2,700 mPas)
Work Time3 hours
Tack-Free Time5 hours
Cured: 15 minutes at 15°C (302°F)
Specific Gravity1.02
Durometer, Type A50
Tensile Strength850 psi (5.9 MPa)
Elongation90%
Lap Shear Strength250 psi (1.73 MPa)
Volatile Content (1 hour at 275°C)0.7%
Volume Resistivity8.5 X 10 exp14
Dielectric Strength610 V/mil (24.0 kV/mm)
Dielectric Constant, 100 Hz2.8
Dielectric Constant, 1 kHz2.8
Loss Tangent, 100 Hz0.0003
Loss Tangent, 1 kHz0.0004
Coefficient of Linear Expansion (-150°C to -170°C)87µm/(m°C)
Coefficient of Linear Expansion (-70°C to 200°C)297µm/(m°C)
Glass Transition Temperature (Tg)-116°C (-176.8°F)
Ionic Content, Na<6 ppm
Ionic Content, K<3 ppm
Ionic Content, Cl<6 ppm

Properties tested on a lot-to-lot basis. Do not use the properties shown in this technical profile as a basis for preparing specifications. Please contact NuSil Technology for assistance and recommendations in establishing particular specifications.


EPM-2422 » Low Volatility Silicone Elastomer

PROPERTIES
Typical PropertiesAverage Result
Uncured:
Appearance*Transparent
Viscosity, Part A*3,600 cP (3,600 mPas)
Cured: 4 hours at 65°C (149°F)
Specific Gravity*1.04
Durometer, Type A*40
Tensile Strength*650 psi (4.5 MPa)
Elongation*100%
Lap Shear Strength* (primed w/CF1-135)200 psi (1.4 MPa)
Coefficient of Linear Expansion
Below Tg (-150° to -115°C)10 ppm/°C (10µm/m/°C)
Above Tg (-95°C to 250°C)490 ppm/°C (490µm/m/°C)
Dynamic Mechanical Analysis (DMA)See Product PDF for Graph
Volatile Content (1 hour at 275°C)0.2%
Ionic Content, Cl<5 ppm
Ionic Content, K< 1 ppm
Ionic Content, Na< 1 ppm

*Properties tested on a lot-to-lot basis. Do not use the properties shown in this technical profile as a basis for preparing specifications. Please contact NuSil Technology for assistance and recommendations in establishing particular specifications.


EPM-2423 » Silicone Elastomer

PROPERTIES
Typical PropertiesAverage Result
Uncured:
AppearanceTransparent
Viscosity, Part A8,000 cP (8,000 mPas)
Work Time2 hours
Tack-Free Time10 hours
Cured: 15 minutes at 150°C (302°F)
Specific Gravity1.02
Durometer, Type A50
Tensile Strength1,000 psi (6.9 MPa)
Elongation125%
Cured: 4 hours at 60°C (140°F)
Lap Shear Strength (primed w/ CF1-135)400 psi (2.8 MPa)

Properties tested on a lot-to-lot basis. Do not use the properties shown in this technical profile as a basis for preparing specifications. Please contact NuSil Technology for assistance and recommendations in establishing particular specifications.


EPM-2461 » Low Volatility Static Dissipative Silicone Elastomer

PROPERTIES
Typical PropertiesAverage Result
Uncured:
Appearance, Part ABlack
Appearance, Part BTranslucent
Appearance, MixedBlack
Viscosity, Part A1,250,000 cP (1,250,000 mPas)
Viscosity, Part B100,000 cP (100,000 mPas)
Work Time1 hour
Cured: 24 hours minimum at ambient temperature and humidity
Durometer, Type A30
Tensile Strength500 psi (3.4 MPa)
Elongation350%
Tear Strength30 ppi (5.3 kN/m)
Volume Resistivity535 ohm cm
Thermal Conductivity*0.223 W/(mK)
Volatile Content (1 hour at 275°C)0.78%
Ionic Content, Cl*<5 ppm
Ionic Content, K*<1 ppm
Ionic Content, Na*<6 ppm

*These properties NOT tested on a lot-to-lot basis. Please contact NuSil Technology for assistance and recommendations in establishing particular specifications.


EPM-2462 » Low Volatility Electrically Conductive Silicone Elastomer

PROPERTIES
Typical PropertiesAverage Result
Uncured:
Appearance*Tan, paste
Work Time*2.75 hours
Cured: 30 minutes at 150°C (302°F)
Specific Gravity*3.39
Durometer, Type A*85
Tensile Strength*525 psi (3.6 MPa)
Volume Resistivity*0.005 ohm cm
Thermal Conductivity1.20 W/(mK)(29 x 10-4 cal/(cm sec°C))
Coefficient of Linear Thermal Expansion
Below Tg (-100°C to -50°C)140 ppm/°C (140µm/m/°C)
Above Tg (-30°C to 250°C)215 ppm/°C (215µm/m/°C)
Volatile Content (1 hour at 275°C)0.2%
Ionic Content, Cl<5 ppm
Ionic Content, K<7 ppm
Ionic Content, Na<5 ppm

*Properties tested on a lot-to-lot basis. Do not use the properties shown in this technical profile as a basis for preparing specifications. Please contact NuSil Technology for assistance and recommendations in establishing particular specifications.


EPM-2463 » Low Volatility Electrically Conductive Rtv Silicone Elastomer

PROPERTIES
Typical PropertiesAverage Result
Uncured:
Appearance*Green-gray
Flow, Base* (0.375" plunge for 30 seconds, mix vigorously for 5 minutes prior to testing) 4 inches (10.2 cm)
Work Time*2.5 hours
Cured: 7 days minimum at ambient temperature and humidity
Specific Gravity*3.23
Durometer, Type A*75
Tensile Strength*300 psi (2.1 MPa)
Elongation*70%
Tear Strength*55 ppi (9.7 kN/m)
Lap Shear Strength* (primed w/ SP-120)185 psi (1.3 MPa)
Volume Resistivity* (at 200±5°C)0.003 ohm cm
Thermal Conductivity1.5 W/mK (36 x 10-4 cal/(cm sec°C))

*Properties tested on a lot-to-lot basis. Do not use the properties shown in this technical profile as a basis for preparing specifications. Please contact NuSil Technology for assistance and recommendations in establishing particular specifications.


EPM-2480 » Dielectric Silicone Gel

PROPERTIES
Typical PropertiesAverage Result
Uncured:
Appearance*Transparent
Viscosity* (tested within 15 minutes after catalyzation)2,500 cP (2,500 mPas)
Work Time*>30 hours
Cured: 30 minutes at 150°C (302°F)
Penetration* (GCA Penetrometer, 19.5 g shaft, 6.35 mm diameter, 5 seconds)4 mm
Volume Resistivity1 x 1014 ohm cm
Volatile Content (1 hour at 275°C)1.09%
Ionic Content, Cl< 5 ppm
Ionic Content, K<1 ppm
Ionic Content, Na< 2 ppm

*Properties tested on a lot-to-lot basis. Do not use the properties shown in this technical profile as a basis for preparing specifications. Please contact NuSil Technology for assistance and recommendations in establishing particular specifications.


EPM-2481 » Dielectric Silicone Gel

PROPERTIES
Typical PropertiesAverage Result
Uncured:
Appearance*Transparent
Viscosity, Part A*16,000 cP (16,000 mPas)
Viscosity, Part B*8,500 cP (8,500 mPas)
Viscosity, Mixed*18,000 cP (18,000 mPas)
Cured: 30 minutes at 150°C (302°F)
Penetration* (Labline Penetrometer, 19.5 gram shaft, 1/4 inch foot, 5 seconds)0.4 mm
Volume Resistivity1 x 1014 ohm cm
Volatile Content (1 hour at 275°C)0.8%
Ionic Content, Cl< 5 ppm
Ionic Content, K< 1 ppm
Ionic Content, Na< 2 ppm

*Properties tested on a lot-to-lot basis. Do not use the properties shown in this technical profile as a basis for preparing specifications. Please contact NuSil Technology for assistance and recommendations in establishing particular specifications.


EPM-2482 » Low Volatility Dielectric Silicone Gel

PROPERTIES
Typical PropertiesAverage Result
Uncured:
Appearance*Transparent
Viscosity*1,800 cP (1,800 mPas)
Cured: 40 minutes at 150°C (302°F)
Penetration* (GCA Penetrometer, 19.5 g shaft, 6.35 mm diameter, 5 seconds)3 mm
Volatile Content (1 hour at 275°C)0.3%
Ionic Content, Cl<5 ppm
Ionic Content, K<1 ppm
Ionic Content, Na<4 pmm

*Properties tested on a lot-to-lot basis. Do not use the properties shown in this technical profile as a basis for preparing specifications. Please contact NuSil Technology for assistance and recommendations in establishing particular specifications.


EPM-2490 » Low Volatility Thermally Conductive Silicone Adhesive

PROPERTIES
Typical PropertiesAverage Result
Uncured:
AppearanceWhite
Work Time2 hours
Tack-Free Time4.5 hours
Cured:
Specific Gravity1.53
Durometer, Type A75
Tensile Strength200 psi (1.4 MPa)
Elongation30%
Lap Shear Strength160 psi (1.1 MPa)
Thermal Conductivity1.49 W/mK (36 x 10-4 cal/cmsec°C)
Volatile Content (1 hour at 275°C)0.2%
Moisture Absorption610%
Dielectric Strength610 V/mil (24.0 kV/mm)
Dielectric Constant, 100 Hz3.4
Dielectric Constant, 1 kHz3.4
Loss Tangent, 100 Hz0.002
Loss Tangent, 1 kHz0.001
Coefficient of Linear Expansion (-70°C to 200°C)240µm/(m°C)
Glass Transition Temperature (Tg)-127°C (-196.6°F)
Ionic Content, Na<3 ppm
Ionic Content, K<3 ppm
Ionic Content, Cl<6 ppm

Properties tested on a lot-to-lot basis. Do not use the properties shown in this technical profile as a basis for preparing specifications. Please contact NuSil Technology for assistance and recommendations in establishing particular specifications.


EPM-2491 » Low Volatility Thermally Conductive Silicone Adhesive

PROPERTIES
Typical PropertiesAverage Result
Uncured:
Appearance*White
Viscosity, Part A*900,000 cP (900,000 mPas)
Tack-Free Time*4 hours
Work Time*2 hours
Cured: 4 hours at 65°C (149°F)
Specific Gravity*1.45
Durometer, Type A*75
Tensile Strength*250 psi (1.7 MPa)
Elongation*60%
Tear Strength*55 ppi (9.7 kN/m)
Moisture Absorption, % gain after 168 hour exposure at 85°C (185°F) / 85% R.H.0.03%
Cured: 30 minute at 150°C (302°F)
Thermal Conductivity*1.11 W/(mK)(26 x 10-4 cal/(cm sec°C))

*Properties tested on a lot-to-lot basis. Do not use the properties shown in this technical profile as a basis for preparing specifications. Please contact NuSil Technology for assistance and recommendations in establishing particular specifications.


EPM-2495 » Low Volatility Thermal Interface Silicone Elastomer

PROPERTIES
Typical PropertiesAverage Result
Uncured:
Appearance*White
Extrusion Rate, Part A* (Performed using a SEMCO® 440 nozzlewith an 1/8" orifice and 90 ±5 psi) 140 g/min
Work Time*3 hours
Cured: 30 minutes at 150°C (302°F)
Durometer, Type A*55
Tensile Strength*400 psi (2.75 MPa)
Elongation*225%
Tear Strength*55 ppi (9.7 kN/m)
Thermal Conductivity*0.64 W/(mK)(15 x 10-4cal/(cm sec°C))
Volatile Content (1 hour at 275°C)0.03%
Ionic Content, Cl< 6 ppm
Ionic Content, K< 3 ppm
Ionic Content, Na< 3 ppm

*Properties tested on a lot-to-lot basis. Do not use the properties shown in this technical profile as a basis for preparing specifications. Please contact NuSil Technology for assistance and recommendations in establishing particular specifications.


EPM-2840 » Low Volatility RTV Silicone Adhesive

PROPERTIES
Typical PropertiesAverage Result
Uncured:
Appearance*Translucent
Flow < 2 inches / 5 minutes
Extrusion Rate (Performed using a SEMCO® 440 nozzle with
a 1/8" orifice and 60 +/- 5 psi air pressure)
30 g/min
Tack Free Time 25 minutes
Cure Time (0.02 or 0.51 mm) 2 hours
Cured: 7 days minimum @ ambient temperature and humidity  
Specific Gravity 1.11
Durometer, Type A 35
Tensile Strength 685 psi (4.7 MPa)
Elongation 280%
Dielectric Strength* 1,100 volts/mil (43.3 kV/mm)
Coefficient of Linear Thermal Expansion (CTE)*  
Below Tg (-150°C to -115°C) 90 ppm/°C (90µm/m/°C)
Above Tg (-95°C to 250°C) 320 ppm/°C (320µm/m/°C)
Cured: 10 days @ ambient temperature and humidity  
Lap Shear Strength (Unprimed) 280 psi (1.9 MPa)
Lap Shear Strength (Primed w/SP-120) 290 psi (2.0 MPa)

*Properties tested on a lot-to-lot basis. Do not use the properties shown in this technical profile as a basis for preparing specifications. Please contact NuSil Technology for assistance and recommendations in establishing particular specifications.


EPM-2850 » Low Volatility RTV Silicone Adhesive

PROPERTIES
Typical PropertiesAverage Result
Uncured:
Appearance*Translucent
Viscosity 7,400 cP
Tack Free Time 50 minutes
Cured: 7 days minimum @ ambient temperature and humidity  
Specific Gravity* 1.01
Durometer, Type A* 16
Tensile Strength* 80 psi (0.55 MPa)
Elongation* 200%
Volatile Content (1 hour at 275°C)* 0.7%
Dielectric Strength* 660 V/mil (25.8 kV/mm)

*Properties tested on a lot-to-lot basis. Do not use the properties shown in this technical profile as a basis for preparing specifications. Please contact NuSil Technology for assistance and recommendations in establishing particular specifications.


EPM-2890 » Thermally Conductive Non-Corrosive Rtv Silicone Adhesive

PROPERTIES
Typical PropertiesAverage Result
Uncured:
Appearance*White
Cure Loss3.2%
Extrusion Rate* (Performed using a 14 gauge nozzle with a 0.5" orifice and 90 ±5 psi air pressure) 40 g/min
Tack-Free Time*40 minutes
Cured: 72 hours minimum at ambient temp. and humidity
Appearance*Elastomeric Solid
Specific Gravity*2.33
Durometer, Type A*65
Tensile Strength*400 psi (2.8 MPa)
Elongation*150%
Thermal Conductivity*0.609 W/(mK)(15 x 10-4 cal/(cm sec°C))
Coefficient of Linear Thermal Expansion (-115°C to 250°C)221 ppm/°C (221µm/m/°C)
Glass Transition (Tg)-116°C (-177°F)
Ionic Content, Cl<5 ppm
Ionic Content, K<5 ppm
Ionic Content, Na<5 ppm
Cured: 7 days at ambient temp. and humidity
Lap Shear Strength (unprimed)*225 psi (1.6 MPa)
Cured: 10 days at ambient temp. and humidity
Weight Loss (30 minutes at 275°C (527°F))0.7%

*Properties tested on a lot-to-lot basis. Do not use the properties shown in this technical profile as a basis for preparing specifications. Please contact NuSil Technology for assistance and recommendations in establishing particular specifications.


EPM1-2493 » Low Volatility Silicone Elastomer

PROPERTIES
Typical PropertiesAverage Result
Uncured:
Appearance*White
Viscosity, within 15 minutes of catalyzation*36,000 cP (36,000 mPas)
Viscosity, 2 hours after catalyzation*50,000 cP (50,000 mPas)
Tack-Free Time*13 hours
Cured: 15 minutes at 150°C (302°F)
Specific Gravity*2.34
Durometer, Type A*65
Tensile Strength*180 psi (1.2 MPa)
Elongation*50%
Lap Shear Strength (primed with SP-270)*120 psi (0.8 MPa)
Thermal Conductivity*0.95 W/(mK)(23 x 10-4 cal/(cm sec°C))
Volatile Content (1 hr at 275°C)0.35 %
Volume Resistivity3.4 X1013
Dielectric Strength465 V/mil (18.1 kV/mm)
Dielectric Constant, 100 Hz4.9
Dielectric Constant, 1 kHz4.9
Dissipation Factor, 100 Hz0.003
Dissipation Factor, 1 kHz0.002
Coefficient of Linear Expansion (-70°C to 200°C)200µm/(m°C)
Glass Transition Temperature (Tg)-98°C
Ion Content, Na< 6ppm
Ion Content, K< 3ppm
Ion Content, Cl< 5ppm

*Properties tested on a lot-to-lot basis. Do not use the properties shown in this technical profile as a basis for preparing specifications. Pleasecontact NuSil Technology for assistance and recommendations in establishing particular specifications.


 

Electronic Packaging Materials

EPM Cutaway Graphic

A low stress alternative for advanced electronic packaging, NuSil Technology's Elec­tronic Packaging Materials (EPMs) allow the designer to choose from a unique line of silicones for various levels of packaging. Packaging options include a variety of products from Flip Chip Under Fill to Glob Top.

Silicone's unique chemical composition compared to organic based polymers applies lower shear stress on components during heating and cooling. Lower applied shear stress can be used in applications where hybrid packages utilize materials with various Coefficients of Thermal Expansion (CTE). Silicones offer stress relief during thermal cycling.

Benefits Of Silicone As Electronic Packaging Material

  • Low Moisture Absorption, <0.4%
  • Dielectric Strength, > 500V/mil (0.001 inch) or 20 kV/mm
  • Thermal Stability, -115 °C to 260 °C
  • Low Modulus
  • Low Shrinkage, <1%
  • Low Ionic Content (Na, K, Cl and NH3)
  • Low Outgassing, <1% at 1 hr @ 275°C
  • Available as gels, elastomers and greases
Standard Wire Bond - Flip Chip

Contamination
Silicone adhesives have had a reputation over the years of "contaminating" surrounding areas with silicone oils while the device is in operation. NuSil Technology has addressed this by designing products in our EPM product line to introduce minimal contamination by the following criteria:

  • Contain low concentrations of silicone oils: < 1 % Weight Loss when heated 1 hour at 275 °C.
  • Low Ion Content: < 20 ppm of individual Na, K and Cl ions per MILSTD 883E.
  • Addition Cure Mechanism: This cure mechanism has minimal shrinkage and does not produce chemi­cal by-products, such as acids or alcohols that can affect components in assemblies.
Chart1

Silicone "oils" are low molecular weight silicones generated during the production of silicone polymers. The polymeriza­tion reaction often begins with polyorganosiloxane rings(A.K.A.cyclics) react­ing with short chain silox­ane species that act as chain terminators in the presence of an acid or base catalyst. The reaction is thermody­namically controlled and the concentration of the various chemical species produced is allowed to reach equilibrium over time. The chemical species produced during this reaction are a range of molecular weights of linear and cyclic compounds. Heat and vacuum are applied and the low molecular weight species can be removed. NuSil Technology has been performing this technique, known as "Wiped Film Evaporation" for the Aerospace industry for 30 years and are experts in this technology.



Dynamic Mechanical Analysis (DMA)
ASTM D-4065-01


DIMETHYL SILICONE


Tg

-130°C


Initial E'
4.0 Gpa


Final E'(Gpa)
0.002 Gpa


Tan Delta Above Tg
1-5

 

Chart2

Stress
Silicones have very low Glass Transition Temperatures (Tg) and low Elastic Modulus compared to other organic polymers. There are organic polymers that may have more than one Tg, which can apply stress on sensitive parts during temperature cycling or possessing. The Tg of a typical dimethylsilicone is —65 °C which allows the silicone to maintain its elasticity over large temperature ranges. Even when filled up to 85% (w/w) with ceramic or metallic fillers, the Tg is < —30 °C.

Silicone does have a high Coefficient of Thermal Expansion (CTE) but has an order of magnitude lower Elastic (Storage) Modulus compared to other organic polymers. The lower modulus allows stress relief during thermal cycling that can prevent warping, bending and shearing of sensitive parts within the device.

Inhibition
EPM Gels, Elastomers and Adhesives are designed to provide excellent optical, thermal and mechanical properties. However, some ingredients commonly found in certain adhesives, plastics and elastomers can adversely affect the cure chemistry in these products. NuSil recommends that adhesives, plastics and elastomers be analyzed for cure inhibition prior to selecting the silicone material for use. This evaluation should include materials used in any transfer containers, dispensing hoses, or utensils that come in direct contact with the gel components.

Processing Highly Filled Silicones
Electrical and thermally conductive silicones typically contain dense ceramic or metallic fillers that can settle over time. Prior to mixing Part A and B together, it is recommended to stir the individual Part A and B that contain the dense fillers to ensure the fillers are homogeneously dispersed prior to use. A vacuum chamber should be used to remove the air introduced during mixing. When working with equipment at reduced pressures, ensure container and chamber are rated to withstand the supplier's recommended operational pressure. Before getting started, reference the Material Certification for "Work Time" or other pot life parameters to determine curing time between mixing and applying to application. Place mixed material into appropriate container and fill approximately one quarter of the container's total volume to allow material to rise. It is recommended to slowly apply vacuum up to approximately 28 inches of Mercury (0.95 Barr). Hold vacuum until bubbles are no longer observed forming. Breaking the seal while pulling vacuum will allow bubbles to burst; expediting the process. It is not recommended to remove air via centrifuging from silicones with fillers having a specific gravity > 1. Centrifuging can be used for silicones that do not contain dense fillers.

Improving Adhesion
Since many substrates are difficult to bond to, the surface of the substrate must be modified to allow good wetting of the adhesive to allow chemical and mechanical interaction. Many substrates need to have the surface "activated" to enhance the adhesive's bond to the substrate. There are, in general, four typical techniques that can be used to improve the adhesive bond; primers, plasma, corona and flame treatment. These surface treatments can greatly enhance the adhesive bond and the type of treatment is dependent on configuration complexity, silicone adhesive and substrates. Adhesion is a very complex subject that incorporates principles from several scientific disciplines that are beyond the scope of this discussion.

Biomaterials

Medical Silicones
Biomaterials - Medical Silicones for Healthcare

Advanced Technologies

Advanced Technologies Industrial & Engineering Silicones
Space - Aviation Grade Industrial & Engineering Silicones

Tubing

Food Medical Industrial Grade Silicone Tubing
Food, Medical & Industrial Quality Silicone Tubing

Equipment

Silicone Mixing Dispensing Degassing Equipment
Mixing Dispensing & Degassing Equipment for Silicone