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642 AIR-DRY INSULATING VARNISH

642 Insulating Varnish is a clear, modified polyester designed for use as a protective

coating for printed circuit boards and other electronic equipment. It can also be used 

on transformers and small motor parts where its flexibility and fast cure are an 
advantage. 642 can be applied by spray, brush or dip, and wil air dry or bake rapidly
to form a tough, oil and chemical resistant film.



642 has excellent adhesion to a variety of substrates. Printed circuit boards treated 
with 642 can be easily repaired by soldering or desoldering through the coating. 
642 is resistant to fluorocarbon solvents used in degressing operations.

RECOMMENDED USES

642 Insulating Varnish is recommended for use as a flexible coating for printed circuit

boards and small electronic components (including stators and transformers) which 
require electrical insulation as well as protectioin from moisture and corrosive
environments.

PHYSICAL PROPERTIES

Viscosity @ 77F (25 C)

   Cenipoises							500-1000

Specific Gravity @ 77F (25 C)					0.965-0.985

Solids Content, (1.5 grams-3 hours-220F/104C), %		47-52

Flash Point (ASTM D 56-70, F/C)					83/28

Viscosity Reducer						Xylene

CURE CYCLE

642 Insulating Varnish, when applied as received, dries to the touch in less than thirty

minutes at room temperature. The addition of up to an equal volume of xylene will give 
a thinner coating that will dry in as little as five minutes. 642 can also be baked, at 

temperatures up to 300F(150 C), for a faster, harder cure.

CURED FILM PROPERTIES (Varnish cured 1 hr. at 250F[121C])

	Electrical - Dielectric Strength (ASTM D 115) on copper

		Dry	-	3000 volts/mil

		Wet	-	3000 volts/mil

	Mechanical - Helical Coil Bond Strength (ASTM D 2519 on MW-35)

			77F(25C)	-	7.8 pounds (3.5kg)

	Chemical Resistance - Helical Coil Bond Strength (as above) after exposure to: 

		2% caustic solution for 168 hrs. - 4.7 pounds (2.1kg)

		5% sulfuric acid for 168 hrs.    - 7.4 pounds  (3.4kg)

	Build (as supplied) - 2.4mils.

U.L. 1446 THERMAL ENDURANCE ( C based on 20000 hour intercept)

		Magnet wire		Twisted 	Helical

		Construction		 Pair		 Coil

		MW-28	  	        130		130

		MW-30			180		155

 		MW-35			180		155

		MW-76			180		155

Self Life :

642 Air-Dry has a shelf life of one year when stored in a closed container at 80F (27 C) 
or below.

If you have questions or comments, Please E-mail to market@pleo.com

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