Conformal coating is a thin layer of dielectric material which applied to
a printed wiring board that provides environmental and mechanical
protection to the circuits on the PWB. Conformal coatings protect PCBs
from moisture and contaminants, which prevent short circuits and
corrosion of conductors and solder joints. Conformal coatings also
minimize dendritic growth [electro-migration] of metal between conductors.
There a number of types of Conformal Coatings;
........Acrylic Resin, Epoxy Resion, Silicon Resin, Polyurethane Resin,
Paraxylylene, Ultra-Violet Curing.
Conformal Coating may be applied by either dipping, brushing or spraying
the PCB with the material.
Printed Wiring Board Specifications:
MIL-P-55110: Military Specification, General Specification For
Printed-Wiring Boards
MIL-PRF-31032: Military Specification, General Specification For
Printed Circuit Board/Printed Wiring Board
ANSI/J-STD-001: Requirements for Soldered Electrical and
Electronic Assemblies
IPC-6012: Qualification and Performance Specification for Rigid
Printed Boards
IPC-C-C-830: Qualification and Performance, Insulating Compounds
for Printed Circuits Assemblies
MIL-I-46058C:Insulating Compound, Electrical (for Coating Printed
Circuit Assemblies)
MIL-STD-275: Printed Wiring For Electronic Equipment
MIL-C-47175A(MI) - Compound, Polyurethane, for Conformal Coating
of Electronic Circuitry
MIL-C-14550B - Copper Plating, (Electro-Deposited)
MIL-STD-2118 - Flexible and Rigid-Flex Printed Wiring for
Electronic Equipment Design Requirements for
MIL-T-10727C - Tin Plating: Electro-Deposited or Hot-Dipped, for
Ferrous and Non-ferrous Metals
RoHS - Restriction of Hazardous Substances. Definition of RoHS
Dow Corning Corporation
{RTV Elastomeric Coatings, RTV Elastoplastic Coatings, Solventless Heat
Cure Coatings}
DYMAX Corporation
{Ultraviolet light curing Conformal Coatings}
Electrolube
{Silicone resin/Flexible acrylic coating, Spray on Conformal Coating. US
MIL-1-46058C}
ITW Chemtronics
{High Viscosity Silicone Conformal Coatings}
MG Chemicals
{Protective/Conformal Coatings}
Conformal Coating
FAQ
{Thermospray Company Inc.}
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PWB Production Vendors
Integrated
Circuit Packaging {MCM, MCP, COB, Hybrid Manufacturers}
Adhesives
Manufacturers {Thermal, UV Cure, Conductive, Non-Conductive,
Electrical Conductive, Elastimere}
| Voltage Between Conductors | Minimum Trace Spacing | |
| DC or AC peak volts | Surface Layers | Internal Layers |
| 0 - 100v | 0.005" | 0.004" |
| 101 - 300v | 0.015" | 0.008" |
| 301 - 500v | 0.030" | 0.010" |
Graph of PWB
External Etched Copper Current Capacity: current rating based on
trace cross section in square mils, temperature rise and current in
amperes.
Graph of PWB
Internal Etched Copper Current Capacity: current rating based on
trace cross section in square mils, temperature rise and current in
amperes.
Graphic of Minimum
Annular Ring, What is a Minimum Annular Ring.
Graph of PWB
Ground Potential, moving away from a single point ground connection
[example].
Description
of Ground Loops
Definition of Printed Wiring
Board Terms
The main PWB information page; Printed Wiring
Board Information
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