Lead frame and method of manufacturing the same
A lead frame having a structure that can discharge hydrogen adsorbed during deposition and can reduce a galvanic potential difference between plating layers and a method of manufacturing the same are provided. The method includes forming a Ni plating layer formed of Ni or a Ni alloy on a base metal layer formed of a metal, forming a Pd plating layer formed of Pd or an Pd alloy on the Ni plating layer, heat-treating the Ni plating layer and the Pd plating layer, and forming a protective plating layer on the heat-treated Pd plating layer.
1. A method of providing a lead frame for a semiconductor device, comprising:
providing a base layer formed of a metallic material;
plating a Ni or Ni alloy layer on the base layer;
plating a Pd or Pd alloy layer on the Ni or Ni alloy layer;
heat-treating the Ni or Ni alloy layer and the Pd or Pd alloy layer, and thereby providing a diffusion layer at least in the Pd or Pd alloy layer with metallic constituents of the diffusion layer thermally diffused; and
forming a protective plating layer on the diffusion layer.
2. The method of claim 1 , wherein the heat-treating is performed at a temperature greater than 150° C.
3. The method of claim 1 , wherein the diffusion layer contains Pd and Ni thermally diffused between the Ni plating layer and the Pd plating layer so that a Pd concentration gradually increases from a lower surface of the diffusion layer to an upper surface of the diffusion layer.
4. The method of claim 3 , wherein the Pd concentration at the upper surface of the diffusion layer is between about 5% and about 80%.
5. The method of claim 1 , further comprising removing of an oxide layer formed on a surface of the diffusion layer after formation of the diffusion layer.
6. The method of claim 1 , wherein the protective plating layer is formed of Au or an Au alloy.
7. The method of claim 6 , wherein the Ni or Ni alloy layer is formed to a thickness of 20-80μ″, the Pd or Pd alloy layer is formed to a thickness of 0.5-0.8μ″, and the protective plating layer is formed of an Au alloy or Ag alloy to a thickness of 0.8-1.5μ″.
8. The method of claim 1 , wherein the base layer is formed of alloy 42.
9. A method of providing a lead frame for a semiconductor device, comprising:
forming a first plating layer composed of an Ni alloy on a base metal layer formed of a metal;
heat-treating the first plating layer, and thereby providing a diffusion layer in the first plating layer with metallic constituents of the layer thermally diffused therein; and
forming a protective plating layer on the diffusion layer.
10. The method of claim 9 , wherein the first plating layer is formed of a Ni—Pd alloy.
11. The method of claim 9 further comprising forming of a second plating layer composed of Pd or a Pd alloy on the first plating layer, and the heat-treating step is performed after forming the first and second plating layers.
12. The method of claim 11 , wherein the diffusion layer contains Pd and Ni thermally diffused between the first plating layer and the second plating layer such that a concentration of Pd gradually increases from a lower surface of the diffusion layer to an upper surface of the diffusion layer.
13. The method of claim 12 , wherein the concentration of Pd at the upper surface of the metal diffusion layer is between about 5% and about 80%.
14. The method of claim 9 , wherein the heat-treating is performed at a temperature of greater than 150° C.
15. The method of claim 9 , further comprising removing of an oxide layer formed on a surface of the diffusion layer after formation of the diffusion layer.
16. The method of claim 9 , wherein the protective plating layer is formed of gold (Au) or an Au alloy.
17. The method of claim 9 , wherein the base metal layer is formed of alloy 42.