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About Conductive Film Adhesives


Elastomeric Specialties, Inc. (E.S.I.) manufactures a complete line of silicone and fluorosilicone adhesive for bonding of electronic assemblies. The following characteristics are general guidelines of this family of adhesives.

Electrically conductive with excellent thermal conductivity.
Thermal conductive in several conductivities.
All materials are heat setting at 250 or 330 degrees.
Bonding pressure needs to provide adequate pressure to flow adhesive 1/8" from edge of entire laminate.
Silicone base allows thermal mismatch of materials, allowing CTE decoupling of dissimilar materials. Little thermal stress.
The films are .010 minimum thickness and a maximum suitable to your requirements.
Film widths available up to 16 inches. Lengths available up to 10 feet. Seams can be made without loss of continuity.
All materials can be used at solder temperature without degrading either bond strength or conductivity. No reflow will take place for limited amounts of time.
Storage temperature at 50 degrees F. or lower. Does not require frozen storage.
Storage Life - 200 series (250 degree F. cure) 1 month 300 series (330 degree F. cure) 3 months
Finished assemblies can be reworked. This requires cutting the bond line without damaging the two surfaces.
Easy clean up without scratching or damaging other parts of the assembly. Wood or plastic instruments can be used.
Shore cure time. Once all components are at temperature, cure is 15-20 minutes.
PREPARATION AND BONDING RECOMMENDATIONS

Clean all surfaces for bonding of grease, fingerprints, dust and chemical contaminates are teflon surfaces must be etched. Most metal surfaces can be abraded with Scotchbrite or suitable equivalent, removing all residue with a non film causing solvent to water break surface.
Prime both surfaces with a cotton litho pad or soft tissue making sure to coat each surface with ONLY ONE VERY LIGHT COAT.
Primed surface needs to sit 30 minutes before bonding. Humidity is important to the chemical reaction, 30% to 80% is adequate.
DO NOT HANDLE THE PRIMED SURFACE. Any contaminate will reduce bond strength.
Remove one side of the liner from the adhesive. Starting at the corner, work slowly with consistent light pressure, pulling 180 degrees to the surface. If the material starts to rip, slide the liner back over the area and rub gently to reseal the rip.
Apply the exposed adhesive to the primed area, working slowly to remove air bubbles. Remove other liner in the same manner.
Apply the other primed piece with light pressure.
Curing Pressure
  • Electronically Conductive - 50psi to 500 psi. Surface conditions will dictate how much is necessary. More irregular surfaces will require more pressure.
  • Thermally Conductive - A minimum of 14 psi. This is dependent upon the surfaces being bonded.

  • NOTE: Use adequate pressure to flow adhesive 1/8" from edge of entire laminate.
Pressure must be applied to material before heat exposure.
Make sure the bonding surfaces are AT THE BONDING TEMPERATURE for a minimum of 15 minutes. This is extremely important! If using the 250 degree F. cure, DO NOT bond at 330 degrees! If using the 330 degree F. cure, 250 degrees will not cure the adhesive.
This is a thermoset material and cannot be remelted. To burn off this material, a temperature in excess of 700 degrees F is required. Cutting off the material is recommended if removal is necessary.
CONDITIONS AND TIPS FOR BONDING

CIRCUIT BOARD USE:
Traces
The board can have bare copper traces with annular rings or tin plating. The tin plating will limit the useable temperature to 450 degrees F. but in some systems, this may save one step in board processing.
Heatsinks
Heatsinks can be bare, chemical film or anodized. Anodized surfaces are not electrically conductive. It is not necessary to have any plating to bring the heatsink to a usable bond condition.
Tooling Pins
For best placement, it is recommended that .060 to .250 pins be used. Only use as many pins as are necessary to achieve alignment.
Mixed Materials
It is possible to mix different dielectrics and different substrates on a single backing. For boards having tuning sections, the substrate can actually be bonded on top of a ground plane area of another board. Combinations of electrically and thermally conductive only areas on a board are possible.
Bottom Side of the Board
A duel sided component bonded board can be designed to save space or make a less costly board. This approach may also assist in circuit problems when oscillations may occur. This is the perfect way to save space and fully utilize the board.
Adhesive Filling
It is suggested that all holes be filled when using the electrically conductive adhesive. Plugs can be used or manual clean out when it is necessary.

CHIP OR COMPONENT USE:
Applicable To Larger Chips and Components
LSI chips or ceramic components that will not be altered by the cure temperature. Small chips may be difficult to place and secure.


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Contact Elastomeric Specialties, Inc.
5510 Brooks Street
Montclair, CA 91763
(909) 986-2335
Fax (909) 986-4456