The design techniques discussed in this section are a summary of recommended “Don'ts” based on features that have displayed significant impact on the durability and reliability of your product and equipment in service.
“Don’ts”
Don’t use dissimilar metal (galvanic) couples if it can be avoided.
Don’t use RTV that contains acetic acid.
Don’t use heat shrink (non-sealed) electrical connector boots to stop moisture fluid intrusion.
Don’t mate magnesium to a metal more cathodic than aluminum.
Don’t use acrylic, RTV or varnish type conformal coatings.
Don’t use gold over silver or copper.
Don’t use organic materials that outgas, support fungi, absorb moisture or are degraded by maintenance and operational fluids.
Don’t use an EMI gasket without a seal on both sides of the conductive element.
Don’t use top mounted lid fasteners.
Don’t mount PWBs horizontally.
Don’t mount electrical connectors (multicontact or coaxial) vertically.
Don’t place edge connectors on the bottom edge of a vertically PWB.
Don’t create side loads or cable tension on the rear seal of electrical connectors.
Don’t use direct air cooling on active electronic components.
Don’t mount equipment less than 1/2 inch above the compartment floor.
Don’t use hygroscopic materials.
Don’t use nickel plated electrical connector shells in salt or high humidity environments. (Use cadmium plated shell).
Don’t use foam cushioning material that can deteriorate (revert).
