Aging impact on the accelerated thermal cycling performance of lead-free BGA solder joints in various stress conditions

2012 ◽  
Author(s):  
Tae-Kyu Lee ◽  
Hongtao Ma
Keyword(s):  
Thermal Cycling ◽  
Solder Joints ◽  
Cycling Performance ◽  
Stress Conditions ◽  
Lead Free ◽  
Accelerated Thermal Cycling

Effect of Selected Manufacturing Variables on Reliability of Lead Free Solder Joints

2006 ◽  
Author(s):  
Leila Jannesari Ladani ◽  
Abhijit Dasgupta ◽  
Idelcio Cardoso ◽  
Eduardo Monlevade
Keyword(s):  
Thermal Cycling ◽  
Waiting Time ◽  
Solder Joints ◽  
Lead Free ◽  
Electrical Performance ◽  
Lead Free Solder ◽  
X Rays ◽  
Response Variable ◽  
Accelerated Thermal Cycling ◽  
Free Solder

This paper presents a systematic approach to study the effect of manufacturing variables on the creation of defects and the effect of those defects on the durability of lead free solder joints. An experiment was designed to systematically vary the reflow and printing process variables in order to fabricate error-seeded test assemblies. The error-seeded samples were then inspected visually and with x-rays, to identify different types of defects, and tested for electrical performance. The specimens were put under accelerated thermal cycling test to characterize the durability of specimens and to study the effect of each manufacturing variable on the durability of solder joints. Thus, the response variable for the design of experiments is the thermal cycling durability of the solder joints. Pre-test micro-structural analysis shows that specimens produced under inadequate reflow profiles suffer from insufficient wetting and insufficient intermetallic formation. Statistical analysis of the response variable shows that waiting time, heating ramp, peak temperature and cooling rate have non-linear effects on the response variable. Two variables, in particular (the heating ramp time and the waiting time), appear to have optimum values within the ranges investigated.

Recrystallization of Lead Free Solder Joints: Confounding the Interpretation of Accelerated Thermal Cycling Results?

2009 ◽  
Author(s):  
Ahmad Mayyas ◽  
Liang Yin ◽  
Peter Borgesen
Keyword(s):  
Thermal Cycling ◽  
Solder Joints ◽  
Damage Mechanism ◽  
Lead Free ◽  
Primary Concern ◽  
Implicit Assumption ◽  
Lead Free Solder ◽  
Intergranular Cracking ◽  
Accelerated Thermal Cycling ◽  
Free Solder

A primary concern of any reliability engineer is whether failure in accelerated testing may be caused by a different damage mechanism than the one that determines life in service. The recent suggestion that thermal expansion mismatch induced fatigue and failure of lead free solder joints under realistic service conditions may progress without the recrystallization seen to play a major role in accelerated thermal cycling thus requires systematic investigation. A total different concern is the ever recurring question of to which extent thermal cycling can be replaced by much faster isothermal cycling tests. The observation that the damage mechanisms tend to be completely different, one leading to transgranular cracking the other to intergranular cracking of lead free BGA solder joints, would seem to invalidate such ideas completely. Importantly, most practical service scenarios involve the combination of more than one loading conditions. This may be as simple as thermal excursions to different temperatures or vibrations with two different frequencies or amplitudes, but it may also involve a combination of thermal excursions and vibration, for example. Reliability prediction almost invariably relies on the explicit or implicit assumption of some principle of damage accumulation, most commonly Miner’s rule. These assumptions do, however, break down much more often than commonly recognized. One important reason for this, albeit clearly not the only one, would be the different effects of recrystallization. All of these concerns prompted an ongoing investigation to identify the parameters determining whether recrystallization will affect lead free solder fatigue life and what would be the practical consequences.

A Highly Accelerated Thermal Cycling (HATC) Test for Solder Reliability Assessment in BGA Packages

2007 ◽  
Author(s):  
X. Long ◽  
I. Dutta ◽  
R. Guduru ◽  
R. Prasanna ◽  
M. Pacheco
Keyword(s):  
Thermal Cycling ◽  
Solder Joints ◽  
Low Cycle Fatigue ◽  
Inelastic Strain ◽  
Fatigue Reliability ◽  
Element Analysis ◽  
Mechanical Cycling ◽  
Experimental Apparatus ◽  
Dependent Strain ◽  
Accelerated Thermal Cycling

A thermo-mechanical loading system, which can superimpose a temperature and location dependent strain on solder joints, is proposed in order to conduct highly accelerated thermal-mechanical cycling (HATC) tests to assess thermal fatigue reliability of Ball Grid Array (BGA) solder joints in microelectronics packages. The application of this temperature and position dependent strain produces generally similar loading modes (shear and tension) encountered by BGA solder joints during service, but substantially enhances the inelastic strain accumulated during thermal cycling over the same temperature range as conventional ATC (accelerated thermal cycling) tests, thereby leading to a substantial acceleration of low-cycle fatigue damage. Finite element analysis was conducted to aid the design of experimental apparatus and to predict the fatigue life of solder joints in HATC testing. Detailed analysis of the loading locations required to produce failure at the appropriate joint (next to the die-edge ball) under the appropriate tension/shear stress partition are presented. The simulations showed that the proposed HATC test constitutes a valid methodology for further accelerating conventional ATC tests. An experimental apparatus, capable of applying the requisite loads to a BGA package was constructed, and experiments were conducted under both HATC and ATC conditions. It is shown that HATC proffers much reduced cycling times compared to ATC.

Thermal Cycling Reliability of Chip Resistor Lead Free Solder Joints

2003 ◽  
Author(s):  
N. Islam ◽  
J. C. Suhling ◽  
P. Lall ◽  
T. Shete ◽  
H. S. Gale ◽  
...  
Keyword(s):  
Solder Joint ◽  
Thermal Cycling ◽  
Fatigue Resistance ◽  
Solder Joints ◽  
Lead Free ◽  
Lead Free Solder ◽  
Snagcu Alloy ◽  
Temperature Ranges ◽  
Free Solder

In this study, we have examined the thermal cycling reliability of several lead free chip resistor solder joint configurations. Five sizes of resistors (2512, 1206, 0805, 0603, 0402), 2 temperature ranges (−40 to 125°C and −40 to 150°C), and five different solder types have been examined. The solders include the normal SnAgCu alloy recommended by earlier studies (95.5Sn-3.8Ag-0.7Cu), and several variations that include small percentages of Bismuth and Indium to enhance fatigue resistance. Results have been compared to data for standard 63Sn-37Pb joints.

Pb-Free Process Development for a High End Storage Area Network Application

2007 ◽  
Author(s):  
Sunil Gopakumar ◽  
Francois Billaut ◽  
Eric Fremd ◽  
Manthos Economou
Keyword(s):  
Thermal Cycling ◽  
Cycling Performance ◽  
Lead Free ◽  
Process Window ◽  
Successful Implementation ◽  
Soldering Process ◽  
Wave Soldering ◽  
Free Process ◽  
Plated Through Hole ◽  
The Impact

Lead free solders are being increasingly used in the electronic industry. While most of the electronic products, in terms of volume, are already built lead free, sectors of the industry including high end servers, networking and telecommunications are covered by “lead in solder” exemptions. It is unknown at this point how long these exemptions will last. In addition, many components such as memories have started appearing only in the Pb-free version. As a result, the industry has been pushed to either adopt a mixed assembly process or to transition early to a full Pb-free process. Even though numerous papers have outlined the successful implementation of a Pb-free process, few of them have actually looked at complex high-end multilayer boards in its entirety. This paper focuses on the issues involved in developing an acceptable Pb-free process window for thick, multilayer boards for SMT, Wave soldering, Rework and Press-fit operations. A laminate capable of withstanding Pb-free soldering temperatures was used to construct a 125-mil thick multilayer board with 18 layers which included 8 ground and 10 signal planes. This experiment utilized two popular Pb-free finishes commonly used in the industry: Immersion Silver and high temperature Organic Solderability Preservative (OSP). The widespread SAC 305 alloy with a composition of Sn3.0Ag0.5Cu was used for both SMT and wave soldering. Three sets of assemblies were built: Pb-free, Mixed and Sn/Pb. The mixed assembly mostly used Pb-free components with Sn/Pb solder paste. The impact of increased soldering temperatures on the board, components and reliability of the product were also studied as a part of this research endeavor. Board level reliability tests were conducted by subjecting the boards from 0°C to 100°C Air-to-Air thermal cycling as well as mechanical shock and vibration tests. A suite of reliability and destructive physical analysis (DPA) tests were carried out to establish the quality of the soldering using the eutectic Sn/Pb assembly as the baseline. The study compared the cycling performance of the three sets of assemblies and also looked at the potential impacts of moving to mixed assemblies. Results indicated a reduced process window for Pb-free, especially for the Pb-free wave soldering process due to reduced wetting of the plated through hole barrels as compared to Sn/Pb wave soldering process. The thermal cycling performance of the three sets of assemblies was found to be equivalent after 6000 cycles.

RELIABILITY EVALUATION OF BGA SOLDER JOINTS DURING ACCELERATED LIFE TEST

2006 ◽  
Vol 20 (25n27) ◽  
pp. 4553-4558
Author(s):  
OUK SUB LEE ◽  
NO HOON MYOUNG ◽  
DONG HYEOK KIM ◽  
MAN JAE HUR ◽  
SI WOON HWANG
Keyword(s):  
Solder Joint ◽  
Thermal Cycling ◽  
Solder Joints ◽  
Coefficient Of Thermal Expansion ◽  
Accelerated Life Test ◽  
Lead Free ◽  
Lead Free Solder ◽  
Metal Fatigue ◽  
Mechanical Loads ◽  
Free Solder

The use of BGA (Ball Grid Array) interconnects utilizing the lead-free solder joint has grown rapidly because of its small volume and diversity of application. Thus, it requires the continuous quantification and refinement of lead-free solder joint reliability. The lead-free solder creep and cyclically applied mechanical loads cause metal fatigue on the lead-free solder joint which inevitably leads to an electrical discontinuity. In the field application, BGA solder joints experience mechanical loads during temperature changes caused by power up/down events as the result of the CTE (Coefficient of Thermal Expansion) mismatch between the substrate and the Si die. In this paper, extremely small resistance changes at joint area corresponding to through-cracks generated by thermal fatigue were measured. In this way, the failure was defined in terms of anomalous changes in electrical resistance of the joint. Furthermore the reliability of BGA solder joints in thermal cycling is evaluated by using the modified coffin-Manson criterion which may define and distinguish failure. Any change in circuit resistance according to the accumulated damage induced by the thermal cycling in the joint was recorded and evaluated in order to quantitate reliability of solder joint.

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