Chemical Properties:

Chemical symbol Ag – from the Latin Argentum.

Atomic Number – 47

Atomic Weight – 107.88

Melting Point – 961.9° C (1763.4° F)

Boiling Point – 2212.0° C (4013.6° F)

Specific Gravity – 10.5

Silver is a highly conductive metal used in a wide variety of applications such as jewelry, the reflective surface on mirrors, the light sensitive coating on photographic film and paper, in batteries and numerous electronic applications.

Guidelines:

The primary variables with silver plating are purity, brightness and post treatment.  Brightness is classified as “Bright”, “Semi-Bright” and “Matte”.  Purity will range from 99.0% to 99.9%.  Since brightness is derived from an additive to the bath, the purity will tend to be lower as brightness increases.  Also, solderability will tend to be better with the higher purity, matte finishes.  Where wearability is a concern, the brighter finishes are preferred due to the smoother, harder surfaces.

Thickness of deposit will vary widely, depending on the application.  Most applications require a thickness in the .0003 inch to .0005 inch range.  Under QQ-S-365, the default thickness (if no thickness is specified) is .0005 inch.  However thicknesses of a few thousandths are common where bearing surfaces are involved.

Common Specifications:

QQ-S-365

Types: (Brightness)

Type I      Matte (Dull)

Type II     Semi-Bright

Type III    Fully Bright

Grades (Post Treatment)

Grade A      With Supplemental Tarnish-Resistant Treatment

Grade B       Without Supplemental Tarnish-Resistant Treatment

ASTM B 700

Types (Purity)

Type 1     99.9% minimum purity

Type 2     99.0% minimum purity

Type 3     98.0% minimum purity

Grades (Brightness)

Grade A     No Brighteners

Grade B     Brightened Bath

Grade C     Mechanical Polishing of Grade A

Grade D     Semi-Bright using Brighteners in bath

Classes (Post Treatment)

Class N      No Anti-Tarnish Post Treatment

Class S       With Anti-Tarnish Post Treatment

AMS 2411

Purity     99.9% Minimum

Thickness    As Specified

AMS 2412

Purity     99.9% Minimum

Thickness    As Specified

Note:

Government and/or industry specification(s) should be called out when required by the blue print or per customer requirement. If a specification callout is used as a type of shorthand, then qualify the callout to say that only hardness/thickness certification (as appropriate) is required. A government/industry specification callout invokes additional testing that may not be required and will increase the cost of plating.

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