Study on thermal stability of electroless deposited Ni-Co-P alloy thin film

Interface Reaction Between Electroless Ni–Sn–P Metallization and Lead-Free Sn–3.5Ag Solder with Suppressed Ni3P Formation

“…Because Ni 13 Sn 8 P 3 has a higher Sn content than the Ni-Sn-P deposit, it is speculated that transformation of the Ni-Sn-P deposit into the Ni 13 Sn 8 P 3 compound requires Sn supply from the solder, which is similar to the formation of Ni 2 SnP during the Ni-P/Sn-3.5Ag interfacial reaction. 6,[21][22][23][24] On the basis of these arguments, we believe that polycrystalline Ni 13 Sn 8 P 3 is formed by transformation of amorphous Ni-Sn-P metallization with outward diffusion of Ni and inward diffusion of Sn during the soldering reaction.…”

“…After aging for 200 h, the thickness of the Ni 3 P layer ($5.8 lm) was reduced by approximately 20% as compared with that after aging for 50 h ($7.4 lm), and the thickness of the Ni 2 SnP layer increased to approximately three times that after aging for 50 h. This indicates that, when the Ni-P layer has been fully consumed, the Ni 2 SnP layer grows rapidly at the expense of the Ni 3 P layer. 6 There were few voids in the Ni 3 P layer of the as-reflowed state (Fig. 3a); however, as the reaction proceeded, with aging, the voids in the Ni 3 P layer grew both in size and number ( Fig.…”

“…Accordingly, interfacial reactions between electroless Ni-P and Sn-containing solders, and the implications for long-term reliability, have been widely studied and are well understood. [1][2][3][4][5][6][7][8][9][10] During soldering, reaction between Sn and Ni activates transformation of amorphous Ni-P metallization into a layer of crystalline Ni 3 P containing numerous voids. 11 The mechanism of formation of such voids has also been explained.…”

“…1 Because the Ni 3 P layer has a fine columnar structure, 1,[11][12][13] Ni diffuses rapidly through the layer, leading to the accelerated interfacial reaction. As a result of this rapid reaction, voids nucleate and grow in the Ni 3 P layer after prolonged reaction, 1,[4][5][6][7]13 contributing to the weakened interface and degraded reliability of the solder joint. To slow the interfacial reaction with lead-free solders, it is necessary to avoid formation of the columnar Ni 3 P layer or to suppress growth of the rapid diffusion path.…”

Study on Preparation and Property of Ni-Co-P Coatings of AZ31B Magnesium Alloy

“…Ni-Co-P alloy coating possed unique properties such as high coercive force, the smaller residual magnetism, high wear resistance, high corrosion resistance and high density magnetic that were widely used in compact disk, MEMS, surface anti-corrosion, aerospace and other fields [1][2][3][4][5][6] . In the present,main preparation methods consisted of electroless plating method, electroplating method and sputtering method, etc., in which the electroless plating was a common method for obtaining Ni-Co-P alloy.Although the plating rate, stability and bath life subjected to certain restrictions, but because of its simple operation, uniform coating, high density and hardness characteristics, it had been widely used in many fields [7][8][9][10][11] .In this paper, the AZ31B magnesium alloy was used as matrix to make electroless Ni-Co-P alloy under the alkaline conditions. the formula and process conditions of Ni-Co-P were systematically studied.…”