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Conformal Coating Training

Conformal Coating Training. Conformal. Coating. What is a conformal coating? What does it do? Why coat? What types are there? How to select? How to apply? How to test?. Conformal. Coating. What is a Conformal Coating?.

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Conformal Coating Training

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  1. Conformal Coating Training

  2. Conformal Coating • What is a conformal coating? • What does it do? • Why coat? • What types are there? • How to select? • How to apply? • How to test?

  3. Conformal Coating What is a Conformal Coating? • A thin protective film that “conforms” to the varied profiles of an electronic circuit assembly. • A breathing membrane that will filter moisture and dirt to protect the assembly from environments.

  4. Conformal Coating Why Coat? • Provide Protection From: • Insulation and Dielectric Failures • Moisture • Heat • Corrosion • Fungus • Dust, Conductive particles IMPROVED CIRCUIT RELIABILITY

  5. Conformal Coating What Does It Do? It should provide... • Good insulation • Good dielectric properties • Good moisture resistance • Good flexibility so as not to stress components... • Ability to be Repaired...

  6. Conformal Coating What Coating Types Are Available?

  7. Conformal Coating How To Select? • Applicable Standards & Specifications • US MIL-I-46058C • IPC-CC-830B • UL - Underwriters Labs 746E • Electrical Properties • Insulation resistance, dielectric constant • Thermal Properties • Operating temperature range, thermal expansion (CTE)

  8. Conformal Coating Acrylic Strengths and Weaknesses

  9. Conformal Coating Epoxy Strengths and Weaknesses

  10. Conformal Coating Polyurethanes Strengths and Weaknesses

  11. Conformal Coating Silicone Strengths and Weaknesses

  12. Conformal Coating How To Apply? • Brushing • Dipping – Manual / Automated • Spraying – Aerosol / Manual / Automated • Flow-Coat – Automated

  13. Conformal Coating Brushing? • Best suited for repair and rework • Keep the brush “loaded” • Flow the coating - DO NOT PAINT! BRUSHApplication

  14. Conformal Coating Dip • Slow speed dip - < 30cm/min (12”/min)– Minimizes air entrapment under components • Slower Removal Rate - < 10cm/min (4”/min)– The slower the speed, the thinner the coating • ALWAYS dip board in vertical position, not horizontal DIPApplication

  15. Conformal Coating Dip • Coating penetrates under components and behind component legs • Coating is applied to both sides simultaneously • Coating thickness controlled by dipping speed & viscosity control • Can be done by hand for small assemblies but best done by machine DIPApplication

  16. Conformal Coating “Double Dipping” DIPApplication • Single Dip – Possibility of Sharp Edges being exposed • Double Dip Solves this Problem

  17. Conformal Coating Automated Dipping • Controls dip speed in and out • Maximizes coverage • Reduces waste • Minimizes Evaporation of Coating Bath DIPApplication

  18. Conformal Coating Spray? • Coating is thinned with solventfor application • Hand Spray • HumiSeal Aerosol products • Automated Equipment • Asymtek / Nordson • PVA SPRAYApplication

  19. Conformal Coating Spraying – Aerosol/Hand • Remember cured coating thickness should be 25 - 75(0.001-0.003”) and material is diluted • Need multiple passes each at 90 degrees and multiple coats, 2 to 3 minimum • Always spray assembly in horizontal with spray gun at ~45 degree angle to board surface SPRAYApplication

  20. Conformal Coating Spraying – Hand/Auto • Relatively Simple • 2-Part Materials may be used • Better Tip and Edge Coverage • Reduced Masking SPRAYApplication

  21. Conformal Coating AEROSOLS • 1B73, 1B15H, 1A33and1A27 • Packaged in 12-oz cans • Good for small users and rework • Lower solids content than liquid products SPRAYApplication

  22. Conformal Coating Selective Spray Equipment SPRAYApplication

  23. Conformal Coating Automated Atomized Spray SPRAYApplication

  24. Conformal Coating FLOWCoating

  25. Conformal Coating How To Test? • Visual Inspection With UV Light • Check Coating Uniformity

  26. Conformal Coating Humiseal Conformal Coatings • Widest product selection • > 50 years experience • Greatest pool of technical knowledge • ISO 9001 Registered • Mil-I-46058C, IPC-CC-830 and UL746E compliant products • VOC compliant materials

  27. Conformal Coating • EASY TO APPLY • Most forgiving of contamination • Dry at room temperatures • Have desirable electrical and physical properties • Fungus resistant • Long pot life • No exotherm during drying- heat sensitive components • Does not shrink • EASY TO REPAIR • VOC and VOC HAPS-free versions available HumiSealAcrylic (AR) Products

  28. Conformal Coating • Excellent chemical and humidity resistance • Outstanding dielectric properties for extended periods • Excellent chemical resistance • Available as single - or two-component • Variety of cure types • Moderately repairable • Chemical strippers • Heat • VOC and VOC HAPS-free versions available HumiSealUrethane (UR) Products

  29. Conformal Coating • Excellent for high temperature service • Good thermal endurance – heat generating devices • Humidity and corrosion resistance • One component, 100% solids – no VOC issues • Thermal or moisture cure • Lower abrasion resistance- softer • High CTE • Mechanically repairable • Not solvent-soluble / Do not vaporize with heat • New Silicone Digesters HumiSealSilicone (SR) Products

  30. Conformal Coating • Two components: 2A53A + 2A53B • High abrasion and chemical resistance • Might be considered “indestructible” • Good electrical properties • Good component anchoring • Very Difficult to Repair • Hard to physically remove • Not removed by solvent • Chemical strippers will attack substrates HumiSealEpoxy (ER) 2A53

  31. Conformal Coating • 1B51 Series (Synthetic Rubber) • High flexibility • Excellent electrical properties • High humidity & corrosion resistance • Good thermal stability, low outgassing • High cohesive strength – tough • Low CTE • Stabile Modulus at lower temps • Must be repaired mechanically • Not solvent soluble / requires aggressive stripper • Does not vaporize with heat HumiSeal1B51 Series (Synthetic Rubber)

  32. Conformal Coating • TempSeal • Strippers • Thinners HumiSealAncillary Products

  33. Conformal Coating Conformal Coating is a Simple Process • Clean • Masking • Coating Application • Dry / Cure • Remove Masking • But if product is not processed correctly… Troubleshooting

  34. Conformal Coating • Poor surface cleanliness is most common cause of coating problems • Adhesion loss • Electrical failures • Coating voids • IPC specifications recommend ionic cleanliness level of < 1.5 g/cm2NaCl equivalence Troubleshooting Surface Cleanliness

  35. Conformal Coating • Need to keep within recommended ranges • Too Thick • Incomplete drying / solvent entrapment • Bubbles • Longer cure times • Shrinking or cracking • Decreased coating properties • Too Thin • Inadequate Protection! Troubleshooting Coating Thickness

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