Chemical Properties:

Chemical symbol Sn –  from the Latin Stannum.

Atomic Number – 50

Atomic Weight – 118.69

Melting Point – 231.9° C (449.4° F)

Boiling Point – 2270.0° C (4118.0° F)

Specific Gravity – 5.31

Tin plating is used primarily where good solderability is needed.  Additionally tin is used to coat hardware for corrosion protection.  Copper buss bars are often tin plated to prevent oxidation of the copper and insure contact when they are installed. 

Guidelines

Tin is plated in either a bright or matte finish.  The bright finish is produced in an acid electrolyte (sometimes referred to as bright acid tin), while the matte finish may be produced from either an acid or alkaline electrolyte.  Both processes produce a pure tin deposit that is solderable.  The matte tin may also be fused (or re-flowed) in a hot oil bath.

Proper thickness of the deposit depends on the end use.  Solberability is best in thicknesses in the range of .0001 to .0003 inch.  Heavier deposits will offer greater resistance to corrosion, but solderability is lessened.

Common Specifications:

MIL-T-10727

Types:  (Method of deposit)

Type I      Electro-depoited

Type II     Hot Dipped*

(*Information only - we do not offer Type II)

Thickness: As specified

ASTM-B545

Thickness:

Class A    0.0001 inch

Class B    0.0002 inch

Class C    0.00032 inch (0.0004 inch for steel)

Class D    0.0006 inch (0.0008 inch for steel)

Class E     0.0012 inch

Class F     0.00006 inch

AMS 2408

Thickness designated by suffix

Example:

2408-1 = 0.0001 inch minimum thickness

2408-2 = 0.0002 inch minimum thickness

etc..

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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