DOWSIL™ SE 9186 L Sealant FEATURES & BENEFITS

• Fast, tack-free surface at room  temperature 

• Flowable

• Cures to soft, low stress elastomer 

• Controlled silicone volatility 

• No added solvents 

• Room temperature cure, no ovens  required 

• Mild heat can accelerate cure and  speed in-line processing • Soft coating can improve reliability  against stress

COMPOSITION

• Polydimethylsiloxane One-part, translucent or black, fast tack-free flowable conformal  coating/adhesive with controlled volatility 

APPLICATIONS

DOWSIL™ SE 9186 L Sealant is used for: 

• Rigid and flexible circuit boards 

• Spot protection on components 

TYPICAL PROPERTIES

Specification Writers: These values are not intended for use in preparing  specifications. 

Property Unit Result 

One or Two Part One Color 

Translucent and Black  Viscosity cP Pa-sec 27000 27

Specific Gravity (Cured) 1.02 

Low Molecular Weight Siloxanes (D4-D10) 

Clear Version / Black Version ppm 23 / 29 

Low Molecular Weight Siloxanes (D4-D20)

Clear Version / Black Version ppm 169 / 233 

Tack-Free Time at 25°C minutes 8

Cure Time (20°C/55% RH/1 mm) hours 5 

Durometer Shore A 25

Tensile Strength MPa 1.6 

Elongation % 340

Adhesive Strength (Glass) N/cm² 92

Dielectric Strength Volts/mil kV/mm 575 23

Volume Resistivity Ohm.cm 6.0E+15 

Dielectric Constant at 1 MHz 2.7 

Dissipation Factor at 1 MHz 0.001UNRESTRICTED – May be shared with anyone ®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow DOWSIL™ SE 9186 L Sealant © 2017 The Dow Chemical Company. All rights reserved. Form No. 11-3276-01 C 2

DESCRIPTION Solventless RTV elastomeric  conformal coatings require  atmospheric moisture to cure needing  no expensive ovens, and various  viscosity versions facilitate different  application methods. This family of  coatings is rapidly gaining popularity  because there are no added solvents,  its rapid cure rates can be dramatically  accelerated by mild heat, and its cost  effectiveness. These elastomers, when  cured, offer the optimum stress relief  for even the most delicate components  and interconnections in a variety of  service environments. This product  line also features coatings  manufactured for controlled volatility  and many of these products are UL  recognized. Conformal coatings are  materials applied in thin layers onto  printed circuits or other substrates.  They provide proven, cost effective  environmental and mechanical  protection to significantly extend the  life of the components and circuitry. 

APPLICATION METHODS 

• Syringe 

• Brush 

• Flow coating 

PROCESSING/CURING 

Time to cure is dependent on several  variables including the method of  application, film thickness,  temperature and humidity. Tack-free  time in the data table gives an  indication of typical times until  surface is dry enough to handle. Cure  time for full cure are indications of  time needed to develop full physical  properties such as durometer, tensile  strength or adhesion. These times,  including full cure time, can be  significantly improved by introducing  mild heat of 60°C or less.

POT LIFE AND CURE  RATE 

The pot life of Dow RTV conformal  coatings is dependent on the  application method chosen. To extend pot life, minimize  exposure to ambient moisture by  using dry air or dry nitrogen  blanketing whenever possible. 

ADHESION 

With RTV cure coatings, adhesion  typically lags behind cure and may  take up to 72 hours to build in some  coatings. Dow conformal coatings are  formulated to provide adhesion to  most common substrates and  materials. It is recommended that the  coatings be applied to clean and dry  substrates prior to application. On  certain difficult, low-surface energy  surfaces, adhesion may be improved  by priming or by special surface  treatment such as chemical or plasma  etching. 

USABLE LIFE AND  STORAGE 

Special precautions must be taken to  prevent moisture from contacting Dow  RTV conformal coatings. Containers  should be kept tightly closed and head  or air space minimized. Partially filled  containers should be purged with dry  air or other gases, such as nitrogen.  The product should be stored in its  original packaging with the cover  tightly attached to avoid any  contamination. Store in accordance  with any special instructions listed on  the product label. The product should  be used by its Use Before date as  indicated on the product label. 

USEFUL TEMPERATURE  RANGES

For most uses, silicone adhesives  should be operational over a  temperature range of -45 to 200°C  (-49 to 392°F) for long periods of  time.However, at both the low- and  high temperature ends of the  spectrum, behavior of the materials  and performance in particular  applications can become more  complex and require additional  considerations. For low-temperature performance,  thermal cycling to conditions such as - 55°C (-67°F) may be possible, but  performance should be verified for  your parts or assemblies. Factors that  may influence performance are  configuration and stress sensitivity of  components, cooling rates and hold  times, and prior temperature history.  At the high-temperature end, the  durability of the cured silicone  elastomer is time and temperature  dependent. As expected, the higher the  temperature, the shorter the time the  material will remain useable. 

REPAIRABILITY 

In the manufacture of PCB system  assemblies, it is often desirable to  salvage or reclaim damaged or  defective units. Dow conformal  coatings offer excellent repairability  because they can be removed from  substrates and circuitry by scraping or  cutting, or by using solvents or  stripping agents. If only one circuit  component is to be replaced, a  soldering iron may be applied directly  through the coating to remove the  component. Proper ventilation of any  fume should be employed. After the  circuit board has been repaired, the  area should be cleaned by brushing or  by using solvent, then dried and  recoated. Heat cure coatings can be  repaired with RTV coatings, but heat  cure coatings may not work well when  used to repair RTV coatings. 

PACKAGING  INFORMATION 

Multiple packaging sizes are available  for this product. 

HANDLING  PRECAUTIONS PRODUCT SAFETY  INFORMATION REQUIRED FOR  SAFE USE IS NOT INCLUDED IN THIS DOCUMENT.