• Journal of the Korean institute of surface engineering
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• v.55 no.4
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• pp.202-214
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• 2022

Internal connections between device, package and external terminals for connecting packaging and printed circuit board are normally manufactured by electroless Ni-P plating followed by immersion Au plating (ENIG process) to ensure the connection reliability. In this study, a new non-cyanide-based immersion and electroless Au plating solutions using thiomalic acid as a complexing agent and aminoethanethiol as a reducing agent was investigated on different underlayer electroless Ni-P plating layers. As a result, it was confirmed that the deposition behavior and film properties of electroless Au plating are affected by grain size and impurity of the electroless Ni-P film, which is used as the plating underlayer. Au plating on the electroless Ni-P plating film with a dense surface structure showed the highest bonding strength. In addition, the electroless Au plating film on the Ni-P plating film has a smaller particle size exhibited higher bonding strength than that on the large particle size.

• Korean Journal of Materials Research
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• v.32 no.9
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• pp.361-368
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• 2022

The overall process, from the pre-treatment of aluminum substrates to the eco-friendly neutral electroless Ni-P plating process, was observed, compared, and analysed. To remove the surface oxide layer on the aluminum substrate and aid Ni-P plating, a zincation process was carried out. After the second zincation treatment, it was confirmed that a mostly uniform Zn layer was formed and the surface oxide of aluminum was also removed. The Ni-P electroless plating films were formed on the secondary zincated aluminum substrate using electroless plating solutions of pH 4.5 and neutral pH 7.0, respectively, while changing the plating bath temperature. When a neutral pH7.0 electroless solution was used, the Ni-P plating layer was uniformly formed even at the plating bath temperature of 50 ℃, and the plating speed was remarkably increased as the bath temperature was increased. On the other hand, when a pH 4.5 Ni-P electroless solution was used, a Ni-P plating film was not formed at a plating bath temperature of 50 ℃, and the plating speed was very slow compared to pH 7.0, although plating speed increased with increasing bath temperature. In the P contents, the P concentration of the neutral pH 7.0 Ni-P electroless plating layer was reduced by ~ 42.3 % compared to pH 4.5. Structurally, all of the Ni-P electroless plating layers formed in the pH 4.5 solution and the neutral (pH 7.0) solution had an amorphous crystal structure, as a Ni-P compound, regardless of the plating bath temperature.

• Journal of the Korean institute of surface engineering
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• v.55 no.5
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• pp.299-307
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• 2022

Gold plating is used as a coating of connector in printed circuit boards, ceramic integrated circuit packages, semiconductor devices and so on, because the film has excellent electric conductivity, solderability and chemical properties such as durability to acid and other chemicals. In most cases, internal connection between device and package and external terminals for connecting packaging and printed circuit board are electroless Ni-P plating followed by immersion Au plating (ENIG) to ensure connection reliability. The deposition behavior and film properties of electroless Au plating are affected by P content, grain size and mixed impurity components in the electroless Ni-P alloy film used as the underlayer plating. In this study, the correlation between electroless nickel plating used as a underlayer layer and cyanide-free electroless Au plating using thiomalic acid as a complexing agent and aminoethanethiol as a reducing agent was investigated.

• Korean Journal of Materials Research
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• v.24 no.11
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• pp.632-638
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• 2014

We investigated the effects of DMAB (Borane dimethylamine complex, C2H10BN) in electroless Ni-B film with addition of DMAB as reducing agent for electroless Ni plating. The electroless Ni-B films were formed by electroless plating of near neutral pH (pH 6.5 and pH 7) at $50^{\circ}C$. The electroless plated Ni-B films were coated on screen printed Ag pattern/PET (polyethylene terephthalate). According to the increase of DMAB (from 0 to 1 mole), the deposition rate and the grain size of electroless Ni-B film increased and the boron (B) content also increased. In crystallinity of electroless Ni-B films, an amorphization reaction was enhanced in the formation of Ni-B film with an increasing content of DMAB; the Ni-B film with < 1 B at.% had a weak fcc structure with a nano crystalline size, and the Ni-B films with > 5 B at.% had an amorphous structure. In addition, the Ni-B film was selectively grown on the printed Ag paste layer without damage to the PET surface. From this result, we concluded that formation of electroless Ni-B film is possible by a neutral process (~green process) at a low temperature of $50^{\circ}C$.

• Journal of the Korean institute of surface engineering
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• v.32 no.4
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• pp.487-495
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• 1999

In order to form metallic electrodes on PZT (Pb (Zr, Ti)O$_3$) ceramics, plating conditions for optimal electroless Ni deposition were investigated. Pb in PZT is the major component to inhibit the electroless deposition, because it plays a active role of catalytic poison in plating solution. Adhesion of the electroless Ni deposits is measured by push-pull scale test and peel test. Results such as deposition ability, deposition rate, and thickness of deposits showed in terms of concentration of etchant, composition of catalyzing solution, and composition and pH of electroless bath solution.

• Journal of the Korean institute of surface engineering
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• v.47 no.5
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• pp.269-274
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• 2014

Electroless plating process as a solution deposition method is a viable means of preparing conductive metal films on non-conducting substrates through chemical reactions. In the present study, the preparation and properties of electroless Ni-plating on flexible silicone rubber are described. The process has been performed using a conventional Ni(P) chemical bath. Additives and complexing agents such as ammonium chloride and glycine were added and the reaction pH was controlled by NaOH aqueous solution. Ni deposition rate and crystallinity have been found to vary with pH and temperature of the plating bath. It was shown that Ni-films having the high crystallinity, enhanced adhesion and optimum electric conductivity were formed uniformly on silicone rubber substrates under pH 7 at $70^{\circ}C$. The conductive Ni-plated silicone rubber showed a high electromagnetic interference shielding effect in the 400 MHz-1 GHz range.

• Journal of the Korean institute of surface engineering
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• v.40 no.1
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• pp.32-38
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• 2007

Ni coating layers were formed using a newly developed electroless Ni plating solution. The properties of Ni coating layer such as internal stress, hardness, surface roughness, crystallinity, solderability and surface morphology were investigated using various tools. Results revealed that internal stress decreased with plating time and reached $40N/mm^2$ at 20 minutes of the plating time. Hardness increased with increasing P content and thickness. Surface roughness of the pad decreased with Ni and Ni/Au plating. Crystallinity decreased with increasing P content. Solderability based on wettability decreased with Ni and Ni/Au plating. Based on surface morphology, it is expected that Ni coating layer formed using a newly developed electroless Ni plating solution is lower than that formed using a commercial electroless Ni plating solution in possibility of black pad occurrence.

• Korean Journal of Materials Research
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• v.13 no.2
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• pp.101-105
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• 2003

In this study, we have investigated the availability of the electroless Ni-B plating for a diffusion barrier of the bus electrode. The Ni-B layer of 1$\beta$: thick was electroless deposited on the electroplated Cu bus electrode for AC plasma display. The layer was to encapsulate Cu bus electrode to prevent from its oxidation and to serve as a diffusion barrier against Cu contamination of the transparent dielectric layer in AC plasma display. The microstructure of the as-plated barrier layer was made of an amorphous phase and the structure was converted to crystalline at about 30$0^{\circ}C$. The concentration of boron was about 5∼6 wt.% in the electroless Ni-B deposit regardless of DMAB concentration. The electroless Ni-B deposit was coated on the surface of the electroplated Cu bus electrode uniformly. And the electroless Ni-B plating was found to be an appropriate process to form the diffusion barrier.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.708-711
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• 1999

The Cu/Ni/Au lamellar structure is extensively used as an under bump metallization on silicon file, and on printed circuit board(PCB) pads. Ni is plated Cu by either electroless Ni plating, or electrolytic Ni plating. Unlike the electrolytic Ni plating, the electroless Ni plating does not deposit pure Ni, but a mixture of Ni and phosphorous, because hypophosphite Is used in the chemical reaction for reducing Ni ions. The fracture crack extended at the interface between solder balls of plastic ball grid (PBGA) package and conducting pads of PCB. The fracture is duets to segregation at the interface between Ni$_3$Sn$_4$intermetallic and Ni-P layer. The XPS diffraction results of Cu/Ni/Au results of CU/Ni/AU finishs showed that the Ni was amorphous with supersaturated P. The XPS and EDXA results of the fracture surface indicated that both of the fracture occurred on the transition lesion where Sn, P and Ni concentrations changed.

• Resources Recycling
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• v.10 no.2
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• pp.27-33
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• 2001

Reusing of electroless Ni-Cu-P waste solution was investigated in the plating time, plating rate, solution composion and deposit. Plating time of nickel-catalytic surface took longer than that of zincated-catalytic surface. Initial solution with 50f) waste solution additive at batch type was possible to reusing of waste solution. Plating time of initial solution at continuous type took longer 10 times over than that of batch type. Plating time of 50% waste solution additive at continuous type took longer 3.7 times over than that of batch type. Component change of nickel-copper for electroless deposition was greatly affected by depolited inferiority and larger decreased plating rate.