Potting and Encapsulating Silicone Compounds

The TCEI series pourable potting compounds manufactured by EUROLINIA are 100% silicone elastomer compounds designed for potting and encapsulation (sealing against the environment), electrically insulating, vibration, and shock dampening, and providing efficient heat dissipation to the electric/electronic circuits and boards.

Key Features and Performance Specs

  • After curing at room temperature the liquid transforms into a firm, silicone rubber compound with high dielectric properties, resistant to vibration and shock, UV rays, oxygen, vapor, and most chemical compounds.
  • The compound is applied by pouring into the product and allows partial or full potting of electronics. The resulting thickness is unlimited, while the specific gravity is within 0.1-1.5%.
  • Available in standard white, gray, black, pink, red, brown, or any custom colors.
  • Gel time (liquid state) is about 10-40 minutes at room temperature. The estimated cure time is less than 24 hours at room temperature, and less than 2 hours at +70 ºС (158°F).
  • The compounds do not emit harmful substances while the curing process and further during the operation.
  • Silicone compound does not cause corrosion of metals and alloys.
  • Excellent unprimed adhesion to most plastics, metal, ceramics, and glass.
  • Heavy-duty compounds can be used as adhesives when pre-applied to bonding surfaces (primers) for higher adhesion.
  • The compounds provide effective heat dissipation and electrical insulation due to the high-performance heat-conducting and dielectric properties of ceramic fillers and conforming to contacting surfaces.
  • Pourable and self-leveling.

Given the specific sealing and heat dissipation requirements, EUROLINIA manufactures the silicone potting compound for electronics with various thermal conductivity, depending on nature, dispersed composition, and the amount of the ceramic filler, and also with different filling viscosity.

EUROLINIA potting compounds pouring dynamic viscosity according to Brookfield
ranges from 0.80 to 18.0 Pa*s (800-18,000 mPa*s) at +23 ºС.
It is one of the defining properties when choosing a compound and technology for a particular application.

EUROLINIA Potting Compound Products Line

There are currently 3 silicone compound products manufactured by EUROLINIA:

  • TCEI-1/1 compounds are based on micro powders of highly purified oxide ceramics, recrystallized using a special technology at temperatures above 2000 °C (α-Crystalen™).
  • TCEI-1/2 compounds are based on oxide and nitride ceramic micro powders sintered using a unique technology in a highly purified nitrogen environment at temperatures above 1200 °C (β-Crystalen™).
  • TCEI-1/3 compounds are based on nitride ceramic micro powders.

There are 2 types of filler components produced for each of the above 3 products.

  • L – light filler featuring improved viscosity flow and adhesive properties, while reduced density and firmness;
  • H – heavy filler featuring higher thermal conductivity and electrical resistivity.

Two-Component Silicone Rubber Compounds

Silicone potting materials made by EUROLINIA are fast curing, pourable when liquid RTV2* Silicone Rubber Compounds consisting of a 2-part variable mix ratio potting compound that is when mixed, allows handing the assembly within 10-40 minutes. 
*RTV2 stands for the Two-Component Room Temperature Vulcanization.

The curing of the 2-part silicone compound is performed by mixing the A and B components at room ambient temperature. Depending on the curing procedure, the TCEI silicone compounds feature the following A and B components mix ratios:
  • 1:1 mix ratio compounds (component A + component B) are used for production processes where the silicone potting compound is automatically delivered by using special two-component dispensers.
  • 25:1 – 35:1 mix ratio compounds (component A + catalyst hardener B) are mainly used for manual mixing and potting/encapsulation.

Properly selecting the catalyst component

A catalyst hardener (or a curing agent) determines many of the final properties of a potting compound. Selecting it correctly is as important as that of the silicone because of its significant influence on final cured compound hardness, thermal conductivity, mixed viscosity, and temperature capabilities.

Advantages of the TCEI-1 potting compounds

  • A selection of products featuring various potting properties, thermal conductivity, A & B components mix ratios for potting.
  • A variety of colors: white, gray, black, pink, red, brown. When mixed at a 1:1 ratio A & B components have different colors (shades) to control the quality of the mix before potting.
  • 7-10 working days short lead time, with MOQ from 1 piece at 0.25-2 kg containers.
  • Supplied in polymer containers convenient for mixing the parts before potting.
  • Sealed containers are guaranteed for 6 months from the ship date when stored in a cool dry area below 22ºС (70°F).
  • Optimal price-quality ratio.
  • A primer can be additionally supplied upon the customer’s request to improve the adhesion of the compound to the target surface.

Product Specifications

When operating at high temperatures the TCEI-1 pourable silicone potting compounds have the following life span:

  • No less than 2,500 hours at 200°С
  • No less than 1,500 hours at 250°С

General life expectancy: more than 10 years.

EUROLINIA TCEI-1/1 Product Specs

Property
Product Name
TCEI-1/1L1,00 TCEI-1/1L1,50 TCEI-1/1L2,50 TCEI-1/1H5,50 TCEI-1/1H8,50 TCEI-1/1H12,5
Appearance after cured Solid rubber-like homogeneous material
Color Pink, gray(¹)
Density g/cm³ 1,10 1,50 1,70 1,80 2,00 2,20
Durometer Shore A 35 45 55 60 75 80
Strength of bond with metal when peeling, кN/м 0,75 0,55
Dielectric Strength, KV/mm
D.C.
A.C.


20
15


25
18

Volume Resistivity, Оm•cm 1013 1014
Dielectric Constant at 1,000Hz 6,5
Dielectric loss tangent at 1,000Hz 0,0045
Thermal conductivity, W/(м•К) 0,25 0,40 0,50 0,60 0,70 0,80
Viscosity at 23 °C
– Conditional viscosity according to the VZ-246 viscometer (nozzle 6.0 mm), s
– Dynamic viscosity according to Brookfield at a shear rate of 120 1 / s, mPa*s
50-65

800
-1250

65-80

1400
-2000

85-100

2200
-2750

155-190

4900
-6500

8000
-10500

11000
-13500

Gel time, min 10-40(²)
Cure time, hours
– at 23 °C
– at 70 °C


24
2

Linear shrinkage, % less than 1,5 0,4 0,2 0,1
Water absorption
— Mass absorption,% mass.
— Surface absorption, mg / cm²

0,20
0,55

0,10
0,30

0,05
0,15
(¹) – Any custom color is available according to the customer’s request
(²) – This value depends on the amount of catalyst hardener (component B)

EUROLINIA TCEI-1/2 and TCEI-1/3 Product Specs

Propertiy
Product Name
TCEI-1/2L-6,50 TCEI-1/2H-12,5 TCEI-1/3L-10,5 TCEI-1/3H-15,0
Appearance after cured Solid rubber-like homogeneous material
Color Brown, gray(¹) Gray
Density, g/cm³ 0,80 2,00 1,70 1,90
Durometer Shore A 60 75 55 70
Strength of bond with metal when peeling 0,55
Dielectric Strength, KV/mm
D.C.
A.C.


20
15


15
10

Volume Resistivity, Оm•cm 1013 1012
Dielectric Constant at 1,000Hz 6,5
Dielectric loss tangent at 1,000Hz 0,0045
Thermal conductivity, W/(m•К) 0,70 0,90 1,00 1,20
Viscosity at 23 °C        
— Conditional viscosity according to the VZ-246 viscometer (nozzle 6.0 mm), s 180-
250
— Dynamic viscosity according to Brookfield at a shear rate of 120 1 / s, mPa*s 6000-
8900
11000
-13500
9000-
12500
13000
-18000
Gel time, min 10-40(²)
Cure time, hours
– at 23 °C
– at 70 °C


24
2

Linear shrinkage, % less than 0,2 0,1 0,2 0,1
Water absorption
— Mass absorption,% mass.
— Surface absorption, mg / cm²
0,10
0,30
0,05
0,15
0,10
0,30
0,05
0,15
(¹) – Any custom color is available according to the customer’s request
(²) – This value depends on the amount of catalyst hardener (component B)

Product supply includes the following items:

  • Potting compound (component A, or components A and B at 1:1 mix ratio)
  • Catalyst hardener (component B)
  • User manual
  • Primer component B (optionally by customer’s request)

Silicone Potting of Electronic Assembly

What is potting?

Silicone Potting of Electronic Assembly
Silicone Potting of Electronic Assembly

Potting is the process of filling an electronic assembly with a silicone elastomer or heat-cured powder for resistance to shock and vibration, providing heat dissipation, and protection from dust, moisture, and corrosive agents.

Full or partial potting of the electronic assembly is one of the main applications of the TCEI-1 adhesive silicone RTV compounds.

Providing electrical insulation and thermal conductivity, they can perform in temperatures ranging from -60 to +250°C (-76 to +482°F).

Normally, the resulting potting compound layer thickness does not exceed 4-6 mm. Choosing the correct compound viscosity and the potting method, it is possible to pour 0.1-0.3 mm gaps between the board and the case.

Silicone Potting Process

  1. Prepare the surfaces of the electronic board and the case (cleansing, degreasing, applying a primer-sublayer).
  2. Prepare the potting compound: mix the components A and B in the original container to a uniform consistency.
  3. Pour the prepared compound into the case of an electronic assembly.
thermally conductive potting of electronic PCB
Thermally conductive potting with silicone elastomer

Usually, after potting the electronic assembly, it is processed on a vibration table to fill the micro-gaps with the compound and release air bubbles (filling the gas cavities), processing in a vacuum chamber to release micro-air bubbles, holding in a heat chamber at 60-85 °С (140 to +185°F) for faster curing of the silicone compound.

Silicone Encapsulation of Electronic Elements

What is Encapsulation?

Silicone Encapsulation of PCBs
Silicone Encapsulation of Electronic Elements

Encapsulation is the complete or partial application of a compound layer only onto the surface of the electronic board, or the element itself. 

When encapsulating electronics, the compound layer thickness does not exceed 0.5-1.0 mm.

Silicone Encapsulation Process

  1. Prepare the surface of the board and electronic elements: cleansing, degreasing, applying a primer-sublayer, drying.
  2. Prepare the potting compound: mix the components A and B in the original container to a uniform consistency.
  3. Automatically or manually apply the prepared compound onto the electronic board or the element.
  4. Process the encapsulated board in a heat chamber at 60-85 °С (140 to +185°F) for faster curing of the compound.
  5. Perform a visual check of the quality of the encapsulation, and optionally the ultrasonic check of the coating thickness.

Potting and Encapsulation Automated Systems

Nowadays, the processes of potting and encapsulation are quite automated by using special two-component dispensers for mixing, dosing the compounds by volume (mass), and feeding. They also operate potting robots for positioning the dispenser head.

The advantage of automated systems is the ability to fully integrate into the conveyor line for mass production, as well as the ability to work in a semi-automatic mode with an operator using a compound dispensing gun.

Some of the recommended Two-component dispenser manufacturers worth mentioning are: 

  • DOSAMIX, PU, and RIM series equipment by SECMER
  • PD44 and PR70 dispensing systems by Graco
  • LC120FR, MINI, IJ30C, IJ40C by Fisnar Liquid Control

The above-mentioned automated dosing systems allow using components A and B with different viscosities, including silicones with various fillers, with a mixing ratio from 1:1 to 100:1.

EUROLINIA TCEI-1 pourable potting and encapsulation silicone compounds have proven their full compliance with the requirements of this dosing equipment in terms of mixing and dosing accuracy.

Directions for Use

Full potting (see Picture 4) guarantees reliable sealing against the external environment, dampens shocks and mechanical stress, provides electrical insulation, as well as effective heat dissipation simultaneously from all electronic elements through the compound to the product chassis/sink and into the environment.
  1. Components A and B are mixed right before use. For silicone compounds with a 1:1 mix ratio, add 1 mass part of component B to 1 mass part of component A. For compounds with a 25-35:1 mix ratio, add 1 mass part of component B to 25-35 mass parts of component A. If the product has been stored for more than 60 days from the manufacture date, the performance of the compound may change due to the partial expiration of the catalyst. In this case, a preliminary check and correction of the potting silicone compound are necessary.
  2. Before use, components A and B must be thoroughly mixed in the manufacturer’s container for at least 1-2 minutes (see Picture 1). Existing sediment, or pigmentation spots on the surface during storage, is not a sign of a defective product. Sediment and pigment spots should disappear after mixing the components. It is allowed to mix components A and B with solvent gasoline of the BR-2 type TU 38.401-67-108 or nefras C2-80 / 120 according to the manufacturer’s technical regulations to achieve the required filling viscosity (consistency) in a ratio of no more than 3 mass parts of solvent to 100 weight parts of component A or B.
  3. The resulting TCEI-1 silicone compound mix should not contain air bubbles, dust particles, or other inclusions in the material when potting or encapsulating products.
  4. Before applying the compound, the surfaces of the product should be thoroughly cleaned of dust, dirt, and other debris with hairbrushes, cloth napkins, or by blowing with compressed air. To remove moisture, traces of mineral oils, grease stains, and other contaminants, the surfaces are degreased with a cloth soaked in solvent gasoline or isopropyl alcohol. After solvent treatment, the surfaces should be wiped with a dry, clean cloth, or dried in air/oven. Secondary degreasing is performed if necessary in the same order.
  5. The compound is applied onto the surfaces with a spatula, syringe, dosing head, or other potting/encapsulation devices (see Picture 2).
  6. The bond strength can be increased by applying a sublayer (primer) SS4120, SS4155 by GE Silicones; Ambersil Primer No. 3 by Ambersil Silicones; Dow Corning 1200 RTV Prime Coat by Dow Corning. Keep in mind that the adhesive properties of the compounds are fully achieved within 2-14 days after cure.
  7. For best coating quality the TCEI-1 adhesive silicone compounds curing is recommended to be performed at room temperature. Complete curing should be done at temperatures 15-70 °C (59-158°F).
  8. Compound potting of electronics is done by partially or completely filling the products (see Pictures 3 and 4), as well as by applying them onto the surface in the form of a thermally conducting layer protecting against the external environment or a sealing layer – by encapsulation (see Picture 2). In this case, the compound layer thickness would be 0.5-1.0 mm, and the linear shrinkage does not exceed 0.1-1.5%.

TCEI-1 silicone compounds allow easy repairing of the potted or encapsulated electronic products.

Due to the elasticity and relatively low mechanical durability, the compound layer can be easily opened with a plastic screwdriver or spatula, or cut out with a knife. After the repair is done, the product can again be filled with a potting compound (preferably of the same type) with guaranteed adhesion to the previous layer.

Precautions

  • EUROLINIA TCEI-1 silicone compounds are fire and explosion-proof, water-resistant.
  • If case of contact with the eyes, rinse with plenty of water. 
  • Wash off the skin with a solvent, gasoline, or isopropyl alcohol, followed by washing with soap and water. 
  • Repeated contact with the skin can lead to dryness or cracking.

Manufacturer’s Warranty

  • The manufacturer guarantees the compliance of the TCEI-1 compounds with the declared above product technical specifications, subject to proper conditions of transportation, storage, and use.
  • Stored in the manufacturer’s container Components A, B, and C shelf life is 3 months from the manufacture date.
  • After the shelf life expiry, the TCEI-1 compounds are tested before each use for compliance with the technical requirements. Subject to compliance, the TCEI-1 compounds can be used for their intended purpose.
  • Quality complaints and claims are accepted when returning the products in the manufacturer’s container with the provision of accompanying documents for the products received from the manufacturer.

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