General Description

Kovar is a nominal 29%Ni-17%Co-54%Fe alloy that is a well-known glass-sealing alloy suitable for sealing to hard glasses. Kovar has a nominal expansion coefficient of approximately 5 ppm/°C and inflection temperature of ~450 °C (840 °F).

Kovar (ASTM F15) has been used for making hermetic seals with the harder Pyrex glasses and ceramic materials. This alloy has found wide application in power tubes, microwave tubes, transistors, and diodes. In integrated circuits, it has been used for the flat pack and the dual-in-line package.

Chemical Composition

Grade C% P% S% Mn% Si% Cu% Cr% Mo% Ni% Co% Fe%
Kovar Max 0.03 Max 0.020 Max 0.020 Max 0.50 Max 0.30 Max 0.20 Max 0.20 Max 0.20 28.5-29.5 16.8-17.8 Bal.

Specifications

Grade UNS Werkstoff Nr. ASTM
Kovar K94610 1.3981 F15

Physical Properties

Grade Density Melting Point
Kovar 8.17 g/cm3 1449°C

Mechanical Properties

Grade Tensile Strength N/mm²
Soft 1/4 Hard 1/2 Hard 3/4 Hard Full Hard
Kovar Strip <570 520-630 590-700 600-770 >700
Kovar Wire <585 585-725 655-795 725-860 >860

Coefficient of Expansion

Alloy Linear Coefficient of Thermal Expansion ā,10-6/℃
20-200℃ 20-300℃ 20-400℃ 20-450℃ 20-500℃ 20-600℃ 20-700℃ 20-800℃
Kovar 5.9 5.3 5.1 5.3 6.2 7.8 9.2 10.2

Size Range

Kovar Wire: ¢0.1mm-¢9mm
Kovar Bar: ¢11mm-¢200mm
Kovar Strip: 75-110mm*0.15-22mm

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