Cho-Form® 5526 and 5528 Form-in-Place EMI Shielding Materials0 pages

Cho-Form® 5526 and 5528
Form-in-Place EMI Shielding Materials
Cho-Form 5526 and Cho-Form 5528 materials
provide low gasket closure force requirements with no
loss of compression recovery properties. These room
temperature cure (moisture cure) conductive
elastomers provide similar adhesive, mechanical and
EMI shielding performance to heat cure Cho-Form
elastomers. Both 5526 and 5528 materials are
designed for use on a variety of substrates, ranging
from metallic casting alloys to shielding coatings on
injection molded housings. They are ideal for use on
thin wall PC/ABS parts. Both gasket materials are
ideal for dispensing with automated equipment.
Features and Benefits
• Room temperature / moisture cure system
• Low closure force requirements
• High compression recovery properties
• VOC free (Cho-Form 5528)
• Low material and installed costs
Cho-Form 5526 material combines a room
temperature (moisture cure) silicone resin with silver
particle filler technology to provide low surface
contact electrical resistance, excellent adhesion, and
soft, easily compressible gaskets. Its superior
electrical properties makes 5526 an excellent choice
for higher performance grounding applications, or for
use on semi-conductive surfaces. 5526 material's
one-component, silicone-based resin technology
delivers soft gaskets (typically 35 Shore A). The
material provides strong compression recovery
properties, and its room temperature cure makes
5526 material appropriate for metallic alloy or plastic
housings.
Cho-Form 5528 material combines Chomerics’ silverplated-
copper particle technology with a room
temperature (moisture cure) silicone resin. The resin
system provides a soft gasket while maintaining
excellent electrical, mechanical and shielding
properties. This allows lower closure forces than
other FIP (form-in-place) conductive elastomer
materials. Its room temperature cure allows 5528
material to be used on metallic alloy or plastic
housings. The 5528 formulation maintains the
excellent compression recovery properties normally
found only in thermal cure systems. It is a zero VOC
material, requiring no special handling procedures or
mechanical ventilation for use. Cho-Form 5528
material is available in two package sizes: 850 grams
of material in a 12-ounce metal cartridge (P/N 19-26-
55128-0850), or 2.50 kilograms in a one-liter metal
canister (P/N 19-26-55128-2500). The material has a
six-month shelf life under ambient conditions
(21±5°C).
Processing of Cho-Form 5526 and 5528 Materials
Both materials typically cure in approximately 24
hours at 21ºC (ambient) and 50% relative humidity
(RH). However, the cure can be accelerated to allow
for packing of completed units in non-gasketcontacting
packaging materials in as little as 30
minutes at 65ºC and 85% RH.
Applications Requiring Lower Compression
Forces
Chomerics' patent pending waveform bead shape,
which employs ¼ wavelength cut off slots, can reduce
required closure forces by 20 to 40%.
Shielded Plastic Housings
When these Cho-Form materials are used with
Chomerics’ Cho-Shield® 2052 conductive coatings,
Chomerics can provide a single resource for shielded
plastic housings. All Cho-Form materials can be
applied as beads with cross sections as small as 0.5
mm high and 0.66 mm wide. If design space allows, a
0.85 mm high by 1.0 mm wide bead is recommended,
which will deliver Cpk values of >1.33. Bead location
accuracy within 0.1 mm is possible with the Cho-Form
dispensing system. For more information on these
products, contact Chomerics Applications
Engineering or Cho-Form Business Unit Engineering
at (781) 935-4850.