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Publish Date: Nov 13, 2009


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Conformal Coating and NI RIO Products

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Overview

This paper provides a brief introduction to Conformal Coating benefits and use cases. It also discusses the ELPEGUARD SL 1307 FLZ coating created by Lackwerke Peters that is available on some National Instruments RIO products.

Conformal Coating

Conformal coatings are specially formulated thin film materials that are applied directly to circuit boards or circuit card assemblies (CCAs).  These films provide environmental protection for components and circuitry.  The thin film materials used for conformal coating are normally applied using a process of dipping or spraying the CCA with a liquid or resinous material.  As the material dries, it forms a resilient coating that can protect against moisture, mold, dust, corrosion and other environmental stresses.

Condensation

Condensation can occur when the outside air temperature increases at a faster rate than the electronics.  If the temperature of the electronics reaches the dew point, condensation will occur.  The higher the relative humidity, the closer the dew point is to the current temperature.  This scenario could occur if a product was stored in a vehicle over night.  When the outside air heats up, there is a potential for the electronics to reach their dew point.  This occurs on the aluminum enclosures due to the thermal capacitance of aluminum.  Once condensation forms on the enclosure, there is a higher probability of shorts on the CCA.

The application of a conformal coating prevents condensation from making contact with traces, vias, and integrated circuits (IC’s) on CCAs.  This prevents the formation of corrosion and shorting on these components after exposure to condensation.  Connectors do not benefit from the conformal coating, so corrosion could still occur at the connectors.  The conformal coating is intended to extend the life of the product by protecting the traces, vias, and fine pitch IC’s, but it does not eliminate all environmental risk associated with the connectors.

Figure 1. Conformal coated CCA shows no corrosion after exposure to condensation

Figure 2. Corrosion has occurred on the uncoated CCA after exposure to condensation

To minimize corrosion on connectors, National Instruments recommends the following tips:

•         Mount the system in horizontal orientation, with the I/O connectors facing forward.  This allows condensation to run off the CCA’s and not to pool up in the connectors.

•         Do not create any drip lines with cabling.  All cables should be routed down, so any condensation that occurs on the cable will not be channeled into the connector or product.

•         Ensure the electronics are not in other drip lines

•         To help protect backplane connectors, use a filler module or dust cover in any empty slot.

National Instruments uses ELPEGUARD SL 1307 FLZ to provide environmental protection for certain products.  This modified acrylic resin is manufactured by Lackwerke Peters (see manufacturers datasheet for technical specifications). 

ELPEGUARD SL 1307 FLZ has been approved as a conformal coating by UL under QMJU2.E80315.  Additionally, National Instruments has tested the conformal coated products for the following environmental specification.

 

Environmental

Operating humidity

(IEC 60068-2-4 Test Db)……………….80 to 100% RH, condensing

Additional test reports and datasheets on the coating material, ELPEGUARD SL 1307 FLZ, are available in the Developer Zone.  These tests were not performed on National Instruments products, they are provided to reference the properties of the conform

 

Products Available with Conformal Coating

The table below shows the C Series modules and CompactRIO and Single-Board RIO systems available with conformal coating.  If the particular system or I/O module you need for you application is not available please contact National Instruments.

Figure 3. CompactRIO Packaged and Single-Board RIO Board-Level Systems

Model Number Description
CompactRIO Controllers and Chassis
cRIO-9014CC Real-Time Controller with 128 MB DRAM, 2 GB Storage
cRIO 9113CC 4-Slot, Virtex-5 LX50 CompactRIO Reconfigurable Chassis
Single-Board RIO Devices
sbRIO-9612 Embedded Device with Analog Input and DIO, 400 MHz processor, 2M Gate FPGA
C Series Analog Input Modules
NI 9205CC 32-Channel +/-10V, 16-Bit, 250 kS/s Analog Input Module
NI 9225CC 3-Channel, 300 Vrms Analog Input Module
C Series Analog Output Modules
NI 9265CC 4-Channel, 100 kS/s, 16-Bit, 0 to 20 mA Analog Output Module
C Series Digital Input Modules
NI 9403CC 32-Channel, 5V/TTL Bidirectional Digital I/O Module
NI 9425CC 32-Channel, 24 V, Sinking Digital Input Module
C Series Digital Output Modules
NI 9476CC 32-Channel, 24 V, Sourcing Digital Output Module
NI 9477CC 32-Channel 5 to 60 V, Sinking Digital Output Module
NI 9478CC 16 Ch, 7 µs, Up to 50 V Sinking Digital Output
C Series Communications Modules
NI 9853CC 2 Port, High-Speed Controller Area Network (CAN) Module
NI 9871CC 4-Port, RS485/RS422 Serial Interface Module

 

 

 

 

Downloads

elpeguard_sl_1307_datasheet.pdf

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