Summary of Guidelines

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Figure 7-19. Techniques for Protecting Bonds Between Dissimilar Metals

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Grounding, Bonding, and Shielding for Electronic Equipments and Facilities

References

MIL-HDBK-419A

7.10 SUMMARY OF GUIDELINES.

Bonds must be designed into the system.

Specific attention should be directed to the

interconnections not only in power lines and signal lines, but also between conductors of signal

ground bus networks, between equipments and the ground bus networks, between both cable and

component or compartment shields and the ground reference plane, between structural members,

and between elements of the lightning protection network. In the design and construction of a

facility, signal path, personnel safety, and lightning protection bonding requirements must be

considered along with mechanical and operational needs.

Bonding must achieve and maintain intimate contact between metal surfaces. The surfaces must be

smooth and clean and free of nonconductive finishes. Fasteners must exert sufficient pressure to

hold the surfaces in contact in the presence of the deforming stresses, shocks, and vibrations

associated with the equipment and its environment.

The effectiveness of the bond depends upon its construction, the frequency and magnitude of the

currents flowing through it, and the environmental conditions to which it is subjected.

Bonding jumpers are only a substitute for direct bonds. If the jumpers are kept as short as possible,

have a low resistance and low

ratio, and are not higher in the electrochemical series than the

bonded members, they can be considered a reasonable substitute.

Bonds are always best made by joining similar metals. If this is not possible, special attention must

be paid to the control of bond corrosion through the choice of the materials to be bonded, the

selection of supplementary components (such as washers) to assure that corrosion will affect

replaceable elements only, and the use of protective finishes.

Protection of the bond from moisture and other corrosive elements must be provided.

Finally, throughout the lifetime of the equipment, system, or facility, the bonds must be inspected,

tested, and maintained to assure that they continue to perform as required.

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