Cho-Shield-604

Cho-Shield 604

CHO-SHIELD® 604 is a highly conductive, advanced coating developed for high volume, precise spray applications on circuit boards and semiconductor packages. Combined with innovative technologies and packaging designs, CHO-SHIELD 604 can provide board level or package level EMI shielding of electrical components.

Product Highlights:

  • One component silver-fi lled polyurethane coating
  • Designed for high volume spray application
  • Flexible

Customer Value Proposition:

CHO-SHIELD® 604 is a highly conductive, advanced coating developed for high volume, precise spray applications on circuit boards and semiconductor packages. Combined with innovative technologies and packaging designs, CHO-SHIELD 604 can provide board level or package level EMI shielding of electrical components.

Applied correctly, CHO-SHIELD 604 can replace stamped metal cans, saving valuable board space and reducing the overall cost of board level EMI shielding. CHO-SHIELD 604’s specially formulated fl exible polymer system provides tenacious adhesion and good environmental stability.

Product Benefits:

• One component silver-fi lled polyurethane coating

• Designed for high volume spray application

• Flexible

• Excellent adhesive properties

• Withstands wave solder temperatures in excess of 500°F (262°C)

• Exceptional working life at room temperature. Cures only when heated, i.e., greater than 250°F ( 122°C)

• Environmentally stable

– heat: 1000 hrs. at 150°C

– humidity: 85% RH

– thermal-cycling: 85°C/85% RH)

Application
Recommended Preparation

  1. Clean the substrate: The substrate surface should be clean, dry and free of oils, release agents, dirt and lint.
  2. Mix the material well by placing the can on a paint shaker for 3-4 minutes or mix by hand with a large spatula until all solids are in a homogeneous suspension. Check that no unmixed material remains on the bottom or the sides of the container.
  3. Optional: Strain the material to reduce or eliminate the potential for clogging the spray nozzle. The paint can be strained through a course mesh (1000 micron) flat strainer into a pressure pot for spray. All metal fi llers should be transferred, although a small amount of fi ller clusters might be collected in the strainer.
  4. Optional thinning: Standard thinning can be accomplished with MEK (methylethyl ketone) solvent. During humid days (relative humidity >50% and temperature >85° F/30°C), use n-Butyl alcohol and add up to 8 fl uid ounces per gallon of paint to eliminate blushing (a white tint on the drying surface).

Fluid Delivery System
Low Volume Manufacturing- Spray

Use a standard air gun with approximately 20-50 psi (138-345 kPa) atomizing air. A fluid nozzle with an orifi ce diameter of 0.040 to 0.070 inch (1.016 to 1.778 mm) is recommended. To obtain maximum adhesion and conductivity, dry spraying should be avoided. Adjust the spray pressure to achieve a proper wet fi lm. Siphon feed equipment can be used for small or prototype runs.

Moderate Volume Manufacturing-Spray Gun and Pressure Vessel with Agitation

Use a pressure pot (15 psi, 103 kPa, typical) with large diameter, paddle type agitator at low mixing speed to keep the metal fi llers in uniform suspension. Conventional spray equipment such as HVLP (High Volume, Low Pressure) or DeVilbiss EGA 503 with propeller agitator pressure pots may be used for spray application with approximately 20-50 psi (138- 345 kPa) atomizing air. Use lowest pressure possible. Re-circulation of the paint from the mixing pot through the spray gun and back via a pump delivery system is recommended for greater fi ller uniformity.

High Volume Manufacturing- Robotic Spray Systems

For large volume, precise spray applications, a robotic spray system with constant fluid recirculation should be use to keep conductive particles from separating and settling in the lines. Both ultrasonic and HVLP spray heads may be used to apply the conductive coating. Important factors to consider when determining spray head type are part geometry, masking requirements, overspray tolerance, paint transfer effi ciency, and manufacturing cycle time. A fl uid nozzle with an orifi ce diameter of 0.020 to 0.040 inch (0.508 to 1.016 mm) is recommended.

Nominal Dry Film Thickness

A nominal dry fi lm thickness of 0.001 inches (25 μm, 1 mils) is recommended to obtain > 70 dB shielding effectiveness from 80 MHz to 10 GHz. However, a thinner or thicker coat may be acceptable depending on the shielding requirements of the device being protected. Allow material to dry 10-20 minutes at room temperature between coats to avoid solvent entrapment.

Drying Conditions

  1. Dry at room temperature for 10-20 minutes.
  2. Continue drying for 15 minutes at 302°F ± 5°F (150°C ± 2°C) for 0.001 inches (25 μm, 1 mils) thickness.

Dry longer if thicker fi lm, shorter if thinner fi lm, to achieve desired conductivity.

Clean-up

The spray system, including spray gun, mixing pot, and containers can be cleaned with MEK or Acetone (VOC exempt solvent). Masks can be power washed with Challenge 485S barrier coat.

Storage and Handling

CHO-SHIELD 604 should be stored at 50ºF to 86ºF (10ºC to 30ºC) and has a 9 month shelf life from the date of manufacturing in the original sealed container. CHO-SHIELD 604 is a fl ammable liquid. Please consult the material safety data sheet for proper handling procedures before use.

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Download the Warranty

This warranty comprises the sole and entire warranty pertaining to items provided hereunder. seller makes no other warranty, guarantee, or representation of any kind whatsoever. All other warranties, including but not limited to, merchant ability and fitness for purpose, whether expressed, implied, or arising by operation of law, trade usage, or course of dealing are hereby disclaimed. Notwithstanding the foregoing, there are no warranties whatsoever on items built or acquired wholly or partially, to buyer’s designs or specifications. Limitation of remedy: Seller’s Liability arising from or in any way connected with the items sold or this contract shall be limited exclusively to repair or replacement of the items sold or refund of the purchase price paid by buyer, at seller’s sole option. In no event shall seller be liable for any incidental, consequential or special damages of any kind or nature whatsoever, including but not limited to lost profits arising from or in any way connected with this agreement or items sold hereunder, whether alleged to arise from breach of contract, expressed or implied warranty, or in tort, including without limitation, negligence, failure to warn or strict liability.