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Finger Stock Gaskets - Materials

Beryllium Copper - the ideal shielding material
Beryllium Copper (BeCu) is a high performance metal which can be fabricated into a wide variety of components. Its mechanical and electrical properties make it the ideal material for EMI/RFI shielding products.

Unique Material Properties
Beryllium copper's electrical properties provide shielding effectiveness over an extremely broad frequency range. At the same time, its mechanical properties yield a high deflection range, in addition to a long life without compression set. BeCu finger stock provides maximum spring properties for strength and fatigue resistance, plus excellent conductivity. Available in many plating options, BeCu has a high cycle time and conforms to large gap variations making it the best material for attenuation.

Material Specifications
Beryllium Copper (BeCu)
ASTM B194

Chemical Composition
Beryllium: 1.80-2.00%
Cobalt plus nickel: 0.20% Min.
Cobalt + nickel + iron: 0.6% Max.
Copper: Balance

Physical Properties (heat treated)
Electrical conductivity (% IACS): 22-25
Modulus of elasticity (psi): 18.5 x 106

Mechanical Properties (heat treated)
Temper (1,000 psi) 1/4 HT 1/2 HT
Tensile strength: 175 Min. 185 Min.
Yield strength .2% offset: 150 Min. 160 Min

Stainless Steel
Stainless steel is an economical alternative to beryllium copper for shielding applications where high attenuation is not required. It does not have the electrical conductivity of BeCu and is stiffer. Mechanical considerations generally limit the use of stainless steel to low profile strips and twisted contacts. Items are identified by SS in the notes.

Material Specifications
Stainless Steel
Type 301 Stainless steel possesses good heat and corrosion resistance.

AISI 301 Analysis
C: .15 Max.
Mn: 2.00 Max.
Si: .750 Max.
P: .040 Max.
S: .030 Max.
Cr: 16.00/18.00
Ni: 6.00/8.00
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