Evaluation of Surface Finish on Build Up Substrate

2003 ◽  
Author(s):  
L. Y. Hung ◽  
Y. P. Wang ◽  
C. S. Hsiao
Keyword(s):  
Solder Joint ◽  
Surface Finish ◽  
Joint Strength ◽  
Failure Modes ◽  
Electroless Nickel ◽  
Deposition Process ◽  
Sodium Hypophosphite ◽  
Ball Shear ◽  
Phosphorous Content ◽  
Electroless Ni

In recent years, the most explosive technologies in electronic systems have demanded ever-higher functionality, ever-faster circuit speeds, and always increasing interconnection density. Electrolytic and electroless nickel/gold (Ni/Au) deposition process are used commonly to provide flat, solderable pad surface finish on area array (BGA or CSP) packages and printed wiring boards (PWB). The electroless nickel/immersion gold (ENIG) process is widely used which do not requires plating lines for electrolytic plating, better meets the fine pitch wiring requirements. However, ENIG deposition process may cause or contribute to catastrophic, brittle, interfacial solder joint fractures. ENIG plating has previously shown lower reliability at solder joints. This is because Phosphorous segregation at the interface Sn-Ni intermetallic and Ni layer caused poor adhesion at that interface, especially high phosphorous content (10∼15%) of the electroless Ni. There have been many studies verified that Ni3P formation is a major factor, which causes weaker joint strength and flat fracture surface. Owing to sodium hypophosphite (NaH2PO2) was used to provide electron and return Ni ion to deposit on Cu pad for ENIG plating, it is not dodge that phosphorous element exist at the Ni layer. Hence, ph value, temperature and loading factor (plating area/ plating tank volume) in the plating path are controlled to reduce phosphorous content (less than 10%) to avoid Ni3P formation. Furthermore, ENIG has a potential risk of black pad, because Porous Au plating layer caused the oxidation of Ni layer underneath the Au plating to occur solder joint failure and low shear forces after assembly. In order to overcome foregoing problem, a flip chip ball grid array (FCBGA) test vehicle is used to compare three kinds surface finish electroless Ni/Au, direct gold and solder on Cu pad in this study 63Sn/37Pb solder bump is reflowed onto these substrates. High temperature storage test (HTS) is used to evaluate thickness and structure of IMC to affect solder joint attachment reliability. Ball shear test is used to measurement joint strength at various HTS time. Optical microscopy (OM) and scanning electron mcroscopy (SEM) are used to observe failure modes after ball shear.

Influence of Surface Finish of Cu Electrode on Shear Strength and Microstructure of Solder Joint with Sn-3Ag-0.5Cu

2005 ◽  
Vol 297-300 ◽  
pp. 2864-2869 ◽  
Author(s):  
Ikuo Shohji ◽  
Hiroki Goto ◽  
Kiyotomo Nakamura ◽  
Toshikazu Ookubo
Keyword(s):  
Solder Joint ◽  
Surface Finish ◽  
Heat Exposure ◽  
Treatment Method ◽  
Joint Interface ◽  
Ball Shear ◽  
Ball Shear Test ◽  
Joint Properties ◽  
Free Solder ◽  
Kinetics Of

An influence of a surface finish of a Cu electrode on joint properties of a lead-free solder joint with Sn-3mass%Ag-0.5mass%Cu has been investigated. As the surface treatment method, Ni/Au electroplating, Au electroplating and organic solderability preservative (OSP) treatments were conducted to Cu electrodes. A heat exposure treatment was conducted at 150°C up to 500h in order to investigate the reliability of the solder joint under heat exposure conditions. Ball shear test was performed to examine joint strength. Microstructural observation was conducted to investigate growth kinetics of a reaction layer formed at a joint interface and microstructural revolution in the solder layer.

A Novel Electroless Ni-P Deposition on AZ91D Magnesium Alloy

2010 ◽  
Vol 154-155 ◽  
pp. 1330-1335
Author(s):  
Li Ping Wu ◽  
Zhong Dong Yang ◽  
Jing Jing Zhao ◽  
Yong Ping Xie
Keyword(s):  
Magnesium Alloy ◽  
Electrochemical Impedance ◽  
Electroless Nickel ◽  
Deposition Process ◽  
Chemical Compositions ◽  
Good Adhesion ◽  
Plating Bath ◽  
Az91d Magnesium Alloy ◽  
Structure Morphology ◽  
Electroless Ni

Currently, most of electroless nickel phosphorus plating on magnesium alloys has following disadvantages. First, it has been suffering from corrosion issues caused by acidic electroless bath. Second, in order to increase the strength of Ni-P coatings to the Mg substrate, the pretreatments for electroless Ni-P employ hydrofluoric acid (HF) and hexavalent chromium (Cr6+) which can cause pollution and health problems . In this paper, we developed HF-free and alkaline electroless Ni-P deposition process on AZ91D magnesium alloy which avoids the use of SO42- and Cl- ions in the electroless plating bath, thus leading to good adhesion and corrosion resistance of electroless Ni-P coating on magnesium alloy. XRD, SEM, EDS techniques were used to study the structure, morphology, and chemical compositions of the conversion coating and Ni-P coating, respectively. Polarization measurements indicated that the corrosion rate of Ni-P coated Mg was six times lower than that of bare Mg. Electrochemical impedance spectroscopy (EIS) also showed that the Ni-P coating could effectively protect Mg alloy from corrosion.

Emerging Flux Challenges for BGA Packages

2016 ◽  
Vol 2016 (DPC) ◽  
pp. 001359-001390
Author(s):  
Maria Durham ◽  
Andy Mackie ◽  
Jason Chou
Keyword(s):  
Solder Joint ◽  
Failure Modes ◽  
Value Added ◽  
Ball Grid Array ◽  
Deposition Process ◽  
Testing Methods ◽  
Bga Packages ◽  
Bga Package ◽  
One Step ◽  
Process Cost

The formation of a Ball Grid Array (BGA) solder joint is critical for a BGA package where typically a flux deposition process is used. Reflowing solder spheres to solderable pads on the bottom of substrates in standard BGA, FCBGA, CSP, and similar packages is considered to be a trivial step: a specialized BGA flux is usually pin-transferred onto the pads, followed by balldrop onto the substrate. However, with the increasing complexity and number of assembly processes taken prior to this final step, the formation of a reliable final joint is far from certain. In order to eliminate variability, many OSATs and ODMs use the so-called “two step” (double fluxing) approach, which is comprised of the non-value-added extra processes of prefluxing, reflowing, cleaning, and drying substrates immediately prior to the final flux-based ball-attach process. This paper details the sequence of processes seen in typical FCBGA assembly, and examines the effects of each set of prior processes on the solderability of the final pad. The introduction of a “one-step” pin-transfer ball-attach flux is shown to be a means of reducing both process cost and time, and also reducing the risk of increased warpage in the finished package. The paper also investigates the solderable surface and metallurgy of the substrate pad. The variety of new and emerging failure modes for the BGA process as well as the different testing methods for the materials will also be discussed.

Joint Strength and Microstructure for Sn-Ag-(Cu) Soldering on an Electroless Ni-Au Surface Finish by Using a Flux Containing a Cu Compound

2008 ◽  
Vol 37 (6) ◽  
pp. 806-814 ◽  
Author(s):  
Seishi Kumamoto ◽  
Hitoshi Sakurai ◽  
Youichi Kukimoto ◽  
Katsuaki Suganuma
Keyword(s):  
Surface Finish ◽  
Joint Strength ◽  
Electroless Ni

Process of Ni-P Electroless Deposition on SiCp/Al Composites from Acid Bath

2010 ◽  
Vol 160-162 ◽  
pp. 314-318 ◽  
Author(s):  
Jian Zhong Li ◽  
Yan Wen Tian ◽  
Ying Li ◽  
Xiang Rong Wang
Keyword(s):  
Electroless Plating ◽  
Electroless Nickel ◽  
Mass Gain ◽  
Deposition Process ◽  
Al2o3 Film ◽  
Nickel Deposition ◽  
Sic Particles ◽  
Acid Bath ◽  
Gain Loss ◽  
Electroless Ni

The initial nickel deposition for the direct electroless nickel plating on active SiCp/Al composites is critical. So it is necessary to investigate the process of the electroless Ni-P plating deposition on SiCp/Al composites by means of scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). In addition, the mass gain/loss in the initial nickel deposition process was measured by using the electro-balance. The results show that after being treated using phosphoric acid and hydrogen peroxide, the compositions of SiCp/Al composites substrate contains Al, SiC and Al2O3. The Al2O3 film was gradually corroded by the plating solution. And then Ni-P coating was deposited on the substrate without Al2O3 film during the initial electroless plating process, which was mostly growing on the boundary between the SiC particles and the Al crystal of the activation substrate, and then came to two sides. After that, the Ni-P coating growth rate to cover with the SiC particles and Al crystals was prior to the Al2O3 film. The electroless plating was in company with the substrate corrosion, but the electroless plating rate catalyzed by the exchanged nickel was more than the substrate corrosion rate.

Effects of Cu contents in flux on microstructure and joint strength of Sn–3.5Ag soldering with electroless Ni–P/Au surface finish

2012 ◽  
Vol 52 (11) ◽  
pp. 2716-2722 ◽  
Author(s):  
Hitoshi Sakurai ◽  
Keun-Soo Kim ◽  
Kiju Lee ◽  
Chang-Jae Kim ◽  
Youichi Kukimoto ◽  
...  
Keyword(s):  
Surface Finish ◽  
Joint Strength ◽  
Electroless Ni

Interfacial Microstructure and Joint Strength of Sn-Ag and Sn-Ag-Cu Lead Free Solders Reflowed on Cu/Ni-P/Au Metallization

2006 ◽  
Vol 512 ◽  
pp. 355-360
Author(s):  
Akio Hirose ◽  
Tomoyuki Hiramori ◽  
Mototaka Ito ◽  
Yoshiharu Tanii ◽  
Kojiro F. Kobayashi
Keyword(s):  
Solder Joint ◽  
Interfacial Reaction ◽  
Reaction Layer ◽  
Joint Strength ◽  
Aging Treatment ◽  
Interfacial Microstructure ◽  
Interfacial Reaction Layer ◽  
Solder Balls ◽  
Lead Free Solders ◽  
Electroless Ni

Sn-3.5Ag (Sn-Ag) and Sn-3.5Ag-0.75Cu (Sn-Ag-Cu) solder balls were reflowed on electroless Ni-P/Au plated Cu pad with varying thickness of Au layer (0 to 500nm). In the Sn-Ag solder joint, a P-rich layer including voids, which resulted from Ni diffusion from the Ni-P plating to form Ni3Sn4 interfacial reaction layer, formed at the interface regardless of Au plating thickness. This caused the degradation of the joint strength. On the contrary, the Sn-Ag-Cu solder joint had no continuous P-rich layer formed and showed a higher joint strength than the Sn-Ag solder joint in the case of Au plating of 50nm or less. Cu alloying to the solder promote the formation of (Cu, Ni)6Sn5 instead to Ni3Sn4 as the interfacial reaction layer. The (Cu, Ni)6Sn5 reaction layer can suppress the diffusion of Ni from the N-P plating and thereby inhibit the formation of the P-rich layer. However, in the case of thick Au plating of 250nm or more, a thin P-rich layer formed at the interface even in the Sn-Ag-Cu solder joint and the joint strength was degraded. Au dissolving into the solder from the Au plating during the reflow process may encourage the diffusion of Ni from the Ni-P plating into the solder. As a result, the Sn-Ag-Cu solder joints with 50nm Au coating provided the best joint strength, although its joint strength considerably degraded after the aging treatment at 423K.

Sign in / Sign up

Export Citation Format

Share Document