MIL-STD-1250 Corrosion Prevention And Deterioration Control In Electronic Components And Assemblies S/S By Mil-Hdbk-1250This standard establishes minimum requirements for procedures, materials and systems for protecting electronic components in DoD systems and assemblies from adverse environments. Protective measures shall be sufficient to maintain performance characteristics within specified limits both during and after exposure to moisture, high and low temperatures, corrosive gases, chemicals and microbial fungal attack.

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MIL-STD-1250A

then dissimilar metal contacts should be treated as if protection were required against the worst environment.

5.7.1 Adhesive bonding. Adhesives shall be in accordance with MIL-STD-454. They shall not emit volatile products, attack nearby equipment, or deteriorate under exposure to moisture, air, ozone, fungus, heat or cold. Each assembly shall be thoroughly cured before storing or packaging in next assembly, to preclude outgassing of potentially corrosive organic vapors. Adhesive applications shall be verified under stress and humidity conditions. To minimize bonding problems, attention shall be given to items listed in table V.

5.7.2 Mechanical joints, structural. Bolts, nuts, screws and other fastener hardware items shall be made of corrosion-resistant metal or shall be treated to resist corrosion.

Suitable plating includes nickel, tin, zinc, and cadmium. Rivets, bolts, and threaded fasteners shall be assembled with wet epoxy primer in accordance with MIL-P-23377 or coated with sealant in accordance with MIL-S-81733 or other sealant approved by the procuring activity. Threads shall be avoided in soft metals such as aluminum. When it is necessary to thread into aluminum, sealant in accordance with MIL-S-81733 shall be used. At any joint involving dissimilar metals, measures as defined in table IV shall be taken to prevent galvanic corrosion. Locking compounds in accordance with MIL-S-46163 and MIL-S-22473 shall not be used in contact with cellulosics, methacrylates, polycarbonates, styrenes, or vinyls.

TABLE V. Checklist for adhesive bonding.

(1) Surfaces shall be clean and free from contaminants before cement is applied. (2) Pot life shall be checked to assure good condition of adhesive.

(3) Lids and caps shall be kept tightly closed on containers of both resin and hardener even though next use is anticipated within a few minutes, and even when using systems with 100 percent solids.

(4) Adhesives shall be mixed thoroughly.

(5) Unless otherwise instructed by the manufacturer, adhesive shall be allowed to dry tack-free before curing at elevated temperature.

(6) Assembly shall be cured thoroughly before storing or packaging in next assembly.

(7) Absolute cleanliness shall be maintained; adhesive joints shall not be handled prior to curing.

(8) Dissimilar metal contacts shall be overcoated with insulating organic coatings to prevent corrosion.