PCB Related Field Failures with ImAg Surface Finishes

2007 ◽  
Author(s):  
Anil Kurella ◽  
Aravind Munukutla ◽  
J.S. Lewis
Keyword(s):  
Emerging Markets ◽  
Galvanic Corrosion ◽  
Electrochemical Migration ◽  
Copper Sulphide ◽  
Electronic Components ◽  
Related Field ◽  
Surface Finishes ◽  
Immersion Silver ◽  
Manufacturing Environments

Abstract PCB surface finishes like Immersion silver (ImAg) are commonly used in Pb-free manufacturing environments following RoHS legislation. With this transition, however the numbers of field failures associated with electrochemical migration, copper sulphide corrosion, via barrel galvanic corrosion are on a steady rise. More often than not ImAg surfaces seem to assist these failing signatures. As computers penetrate into emerging markets with humid and industrialized environments there is a greater concern on the reliability and functionality of these electronic components.

Reliability Analysis of Lead-Free Solder Joints with Solder Doping on Harsh Environment

2016 ◽  
Vol 2016 (1) ◽  
pp. 000117-000122 ◽  
Author(s):  
Cong Zhao ◽  
Thomas Sanders ◽  
Zhou Hai ◽  
Chaobo Shen ◽  
John L. Evans
Keyword(s):  
Surface Finish ◽  
Isothermal Aging ◽  
Electroless Nickel ◽  
Lead Free ◽  
Lead Free Solder ◽  
Solder Paste ◽  
Surface Mount ◽  
Surface Finishes ◽  
Free Solder ◽  
Immersion Silver

Abstract This paper investigates the effect of long term isothermal aging and thermal cycling on the reliability of lead-free solder mixes with different solder compositions, PCB surface finishes, and isothermal aging conditions. A variety of surface mount components are considered, including ball grid arrays (BGAs), quad flat no-lead packages (QFNs) and 2512 Surface Mount Resistors (SMRs). 12 lead-free solder pastes are tested; for BGA packages these are reflowed with lead-free solder spheres of SAC105, SAC305 and matched doped solder spheres (“matched” solder paste and sphere composition). Three surface finishes are tested: Organic Solderability Preservative (OSP), Immersion Silver (ImAg), and Electroless Nickel Immersion Gold (ENIG). All test components are subjected to isothermal aging at 125°C for 0 or 12 months, followed by accelerated thermal cycle testing from −40°C to 125°C. Data from the first 1500 cycles is presented here, with a focus on the effect of surface finish on package reliability. Current results demonstrate that the choice of surface finish has a strong effect on reliability. However, different solder materials appear to show different reliability trends with respect to the surface finishes, and the reliability trends of BGA and SMR packages also diverge.

Effect of ENEPIG Surface Finish on the Vibration Reliability of Solder Interconnects

2013 ◽  
Vol 2013 (1) ◽  
pp. 000115-000119 ◽  
Author(s):  
Sandeep Menon ◽  
Adam Pearl ◽  
Michael Osterman ◽  
Michael Pecht
Keyword(s):  
Electroless Nickel ◽  
Copper Metallization ◽  
Printed Wiring Boards ◽  
Solder Interconnects ◽  
Solder Interconnect ◽  
Failure Data ◽  
Surface Finishes ◽  
Interconnect Reliability ◽  
Immersion Silver ◽  
The Impact

Surface finishes are used to preserve and promote solderability of exposed copper metallization on printed wiring boards. While in the best of worlds, the solder used in assembly should dictate the solder interconnect reliability, surface finishes are known to have an effect. The effect of surface finishes on solder interconnect reliability can be particularly strong under high strain rate loading conditions. In this study, durability of solder interconnects formed between BGAs and electroless nickel, electroless palladium, immersion gold (ENEPIG) finished pads assembled using SnPb and SAC305 solders under harmonic vibration loading is examined. ENEPIG test specimens with two thicknesses of palladium were evaluated. Isothermal preconditioning levels at 100°C for 24 hrs and 500 hrs were included to evaluate the impact of intermetalic evolution on the durability of the soldered interconnects. For comparison, tests specimens created with immersion silver (ImAg) finished printed wiring boards were also included. The failure data obtained found the durability of interconnects formed with ENEPIG finish was comparable or better durability than the durability of interconnects formed with ImAg finish irrespective of the solder. The tests indicate that the use of a thicker palladium layer reduced the degradation in durability which occurred from isothermal aging.

Study of immersion silver and tin printed-circuit-board surface finishes in lead-free solder applications

2004 ◽  
Vol 33 (9) ◽  
pp. 977-990 ◽  
Author(s):  
Minna Arra ◽  
Dongkai Shangguan ◽  
Dongji Xie ◽  
Janne Sundelin ◽  
Toivo Lepistö ◽  
...  
Keyword(s):  
Printed Circuit Board ◽  
Circuit Board ◽  
Lead Free ◽  
Lead Free Solder ◽  
Printed Circuit ◽  
Surface Finishes ◽  
Board Surface ◽  
Free Solder ◽  
Immersion Silver

Evaluation of ENEPIG and Immersion Silver Surface Finishes Under Drop Loading

2015 ◽  
Vol 45 (1) ◽  
pp. 391-402 ◽  
Author(s):  
Adam Pearl ◽  
Michael Osterman ◽  
Michael Pecht
Keyword(s):  
Silver Surface ◽  
Surface Finishes ◽  
Immersion Silver

EFFECT OF SURFACE FINISHES ON THE THICKNESS AND MORPHOLOGY OF THE INTERMETALLIC LAYER IN LEAD-FREE SOLDER JOINTS

2004 ◽  
Vol 03 (06) ◽  
pp. 803-813 ◽  
Author(s):  
A. C. SPOWAGE ◽  
C. M. THONG ◽  
P. A. COLLIER ◽  
G. Y. LI
Keyword(s):  
Intermetallic Layer ◽  
Cost Effective ◽  
Electroless Nickel ◽  
Copper Metallization ◽  
Soldering Process ◽  
Surface Finishes ◽  
Joint Characteristics ◽  
Free Solder ◽  
Immersion Silver ◽  
The Impact

One of the most pressing challenges facing today's electronics packaging industry is to identify reliable and cost-effective solder alloys to replace toxic lead containing solder. Besides evaluating new alloy compositions and improving the soldering process, it is important to understand how surface finishes applied to the copper metallization affect the joint characteristics. The characterization of intermetallics during the early stages of nucleation and the growth is hindered by the nanoscopic grain size and layer thickness. This study investigates the impact of PCB finish and solder type on the interfacial intermetallics. Five types of solder and four types of finishes were used: Sn37Pb (SP), Sn3.5Ag (SA), Sn3.5Ag0.7Cu (SAC), Sn2Ag0.5Cu4Bi (SACB) and Sn3Bi8Zn (SBZ) solders, combined with immersion Silver ( I – Ag ), electroless Nickel-immersion Gold (ENIG), Organic Solderability Preservative (OSP) and immersion Tin ( I – Sn ). It was shown that both the SP and SAC solders follow a parabolic growth model and that the surface finish has a significant effect on the intermetallic morphology and growth kinetics. A combined SEM and XRD investigation was shown to be a suitable method for characterizing nanoscale intermetallics.

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