Electromigration studies of lead-free solder balls used for wafer-level packaging

2011 ◽  
Author(s):  
Christine Hau-Riege ◽  
Ricky Zang ◽  
You-Wen Yau ◽  
Praveen Yadav ◽  
Beth Keser ◽  
...  
Keyword(s):  
Lead Free ◽  
Lead Free Solder ◽  
Wafer Level ◽  
Wafer Level Packaging ◽  
Solder Balls ◽  
Free Solder

ALX Polymer for Wafer Level Packaging: Mechanical Property Evaluation After Multiple Lead-Free Solder Reflows

2010 ◽  
Vol 2010 (DPC) ◽  
pp. 001054-001079
Author(s):  
Takeshi Eriguchi ◽  
Orson Wang ◽  
Kaori Tsuruoka ◽  
Yuichiro Ishibashi ◽  
Yong Zhang
Keyword(s):  
Mechanical Property ◽  
Dielectric Constant ◽  
Moisture Absorption ◽  
Lead Free ◽  
Low Dielectric Constant ◽  
Lead Free Solder ◽  
Wafer Level ◽  
Low Dielectric ◽  
Wafer Level Packaging ◽  
Free Solder

For bumping and wafer level packaging (WLP) applications, BCB and polyimide are the predominant spin-on dielectric materials used for re-passivation, redistribution, interlayer dielectric, and stress buffer layers. Each of these materials has their respective strengths and weaknesses. BCB has exceptionally low shrinkage on cure and moisture absorption, low curing temperature, and a low dielectric constant, but is a mechanically brittle material which limits its application in bump-on-polymer applications. Polyimides are superior mechanically to BCB and are utilized more in bump-on-polymer structures, but suffer from much higher shrinkage on cure and moisture absorption (which can lead to blistering if not carefully processed), have higher dielectric constants, and have much higher cure temperatures. ALX spin-on polymer dielectric was developed to combine low shrinkage, low moisture absorption, low dielectric constant, and excellent mechanical and stress buffering properties with a cure temperature between 190C to 250C, depending on the application(1-3). Previous papers have reported the mechanical properties at 190C and the application of ALX in eutectic SnPb solder bump structures. The use of lead-free solder requires reflow temperatures up to 260C. Although ALX polymer is curable at less than 200C, the influence of lead-free solder reflow wasnft investigated. In this presentation we evaluate mechanical property changes of ALX Polymer films after different cure schedules and multiple reflows at lead-free solder temperatures. The impact of these parameters on WLP will be discussed.

Effect of Thickness of Pd Plating Layer on Shear Strength of Lead-Free Solder Ball Joint With Electroless Ni/Pd/Au Plated Electrode

2011 ◽  
Author(s):  
Takahiro Kano ◽  
Ikuo Shohji ◽  
Tetsuyuki Tsuchida ◽  
Toshikazu Ookubo
Keyword(s):  
Reaction Layer ◽  
Shear Force ◽  
Solder Ball ◽  
Lead Free ◽  
Joint Interface ◽  
Lead Free Solder ◽  
Solder Balls ◽  
Free Solder ◽  
Ball Joints ◽  
Electroless Ni

An electroless Ni/Pd/Au plated electrode is expected to be used as an electrode material for lead-free solder to improve joint reliability. The aim of this study is to investigate the effect of the thickness of the Pd layer on joint properties of the lead-free solder joint with the electroless Ni/Pd/Au plated electrode. Solder ball joints were fabricated with Sn-3Ag-0.5Cu (mass%) lead-free solder balls and electroless Ni/Pd/Au and Ni/Au plated electrodes. Ball shear force and microstructure of the joint were investigated. The (Cu,Ni)6Sn5 reaction layer formed in the joint interface in all specimens. The thickness of the reaction layer decreased with increasing the thickness of the Pd layer. In the joint with a Pd layer 0.36 μm thick, the remained Pd layer was observed in the joint interface. In the joint, impact shear force decreased compared with that of the joint without the remained Pd layer. On the contrary, when the thickness of the Pd layer was less than 0.36 μm, the Pd layer was not remained in the joint interface and impact shear force improved. Impact shear force of the joint with the electroless Ni/Pd/Au plated electrode was higher than that with the electroless Ni/Au one.

scholarly journals Growth Kinetics of Reaction Layers in Flip Chip Joints with Cu-cored Lead-free Solder Balls

2004 ◽  
Vol 45 (3) ◽  
pp. 754-758 ◽  
Author(s):  
Ikuo Shohji ◽  
Yuji Shiratori ◽  
Hiroshi Yoshida ◽  
Masahiko Mizukami ◽  
Akira Ichida
Keyword(s):  
Growth Kinetics ◽  
Flip Chip ◽  
Lead Free ◽  
Lead Free Solder ◽  
Solder Balls ◽  
Free Solder ◽  
Kinetics Of Reaction ◽  
Kinetics Of

The Effects of Temperature Cyclic Loading on Lead-Free Solder Joints of Wafer Level Chip Scale Package by Taguchi Method

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Wen-Ren Jong ◽  
Hsin-Chun Tsai ◽  
Hsiu-Tao Chang ◽  
Shu-Hui Peng
Keyword(s):  
Low Temperature ◽  
Shear Strain ◽  
Solder Joints ◽  
Strain Range ◽  
Lead Free ◽  
Lead Free Solder ◽  
Wafer Level ◽  
Chip Scale Package ◽  
Free Solder ◽  
Plastic Creep

In this study, the effects of the temperature cyclic loading on three lead-free solder joints of 96.5Sn–3.5Ag, 95.5Sn–3.8Ag-0.7Cu, and 95.5Sn–3.9Ag-0.6Cu bumped wafer level chip scale package (WLCSP) on printed circuit board assemblies are investigated by Taguchi method. The orthogonal arrays of L16 is applied to examine the shear strain effects of solder joints under five temperature loading parameters of the temperature ramp rate, the high and low temperature dwells, and the dwell time of both high and low temperatures by means of three simulated analyses of creep, plastic, and plastic-creep behavior on the WLCSP assemblies. It is found that the temperature dwell is the most significant factor on the effects of shear strain range from these analyses. The effect of high temperature dwell on the shear strain range is larger than that of low temperature dwell in creep analysis, while the effect of high temperature dwell on the shear strain range is smaller than that of low temperature dwell in both plastic and plastic-creep analyses.

Effect of Electrode Material on Joint Strength of Soldered Joints With Sn-Bi and Sn-Bi-Sb Lead-Free Solder Balls

2013 ◽  
Author(s):  
Akihiro Hirata ◽  
Ikuo Shohji ◽  
Tetsuyuki Tsuchida ◽  
Toshikazu Ookubo
Keyword(s):  
Shear Force ◽  
Lead Free ◽  
Joint Interface ◽  
Intermetallic Compound Layer ◽  
Lead Free Solder ◽  
Ball Shear ◽  
Joint Properties ◽  
Solder Balls ◽  
Plating Solution ◽  
Free Solder

The aim of this study is to investigate the joint properties of Sn-58mass%Bi and Sn-57mass%Bi-0.5mass%Sb low-melting lead-free solder balls on the electroless Ni/Au and Ni/Pd/Au plated Cu electrodes fabricated with a lead-free plating solution. Compared with the conventional Ni plating solution containing lead, the soldered joints with Ni/Au and Ni/Pd/Au electrodes fabricated with the lead-free plating solution showed comparable joint properties. In the joints with Ni/Pd/Au electrodes, ball shear force increased when the Pd layer is dissolved into solder by multi reflows. In both joints with Ni/Au and Ni/Pd/Au electrodes, a part of the Ni layer was dissolved into solder and thus the (Ni,Cu)3Sn4 intermetallic compound layer formed at the joint interface. Ball shear force decreased upon aging due to the growth of the (Ni,Cu)3Sn4 layer at the joint interface.

Creep Analysis of Wafer Level Chip Scale Package (WLCSP) With 96.5Sn-3.5Ag and 100In Lead-Free Solder Joints and Microvia Build-Up Printed Circuit Board

2000 ◽  
Author(s):  
John H. Lau ◽  
Stephen H. Pan ◽  
Chris Chang
Keyword(s):  
Shear Stress ◽  
Printed Circuit Board ◽  
Circuit Board ◽  
Lead Free ◽  
Lead Free Solder ◽  
Wafer Level ◽  
Shear Creep ◽  
Printed Circuit ◽  
Chip Scale Package ◽  
Free Solder

Abstract In this study, time-temperature-dependent nonlinear analyses of lead-free solder bumped wafer level chip scale package (WLCSP) on printed circuit board (PCB) assemblies subjected to thermal cycling conditions are presented. Two different lead-free solder alloys are considered, namely, 96.5wt%Sn-3.5wt%Ag and 100wt%In. The 62wt%Sn-36wt%Pb-2wt%Ag solder alloy is also considered to establish a baseline. All of these solder alloys are assumed to obey the Garofalo-Arrhenius steady-state creep constitutive law. The shear stress and shear creep strain hysteresis loops, shear stress history, and shear creep strain history at the corner solder joint are presented for a better understanding of the thermal-mechanical behaviors of lead-free solder bumped WLCSP on PCB assemblies. Also, the effects of microvia build-up PCB on the WLCSP solder joint reliability are investigated.

Sign in / Sign up

Export Citation Format

Share Document