Accelerated Thermal Cycling Guidelines for Electronic Packages in Military Avionics Thermal Environment

2004 ◽  
Vol 126 (2) ◽  
pp. 256-264 ◽  
Author(s):  
Raghuram V. Pucha ◽  
Krishna Tunga ◽  
James Pyland ◽  
Suresh K. Sitaraman
Keyword(s):  
Thermal Cycling ◽  
Thermal Environment ◽  
Inelastic Strain ◽  
Electronic Packages ◽  
Strain Accumulation ◽  
Material Models ◽  
Process Mechanics ◽  
Accelerated Thermal Cycling ◽  
Damage Mapping ◽  
Board Level

A field-use induced damage mapping methodology is presented that can take into consideration the field-use thermal environment profile to develop accelerated thermal cycling guidelines for packages intended to be used in military avionics thermal environment. The board-level assembly process mechanics and critical geometric features with appropriate material models are taken into consideration while developing the methodology. The models developed are validated against in-house and published accelerated thermal cycling experimental data. The developed mapping methodology is employed to design alternate accelerated thermal cycles by matching the creep and plastic strain contributions to total inelastic strain accumulation in solder under military field-use and accelerated thermal cycling environments, while reducing the time for accelerated thermal cycling and qualification.

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.

scholarly journals Effect of Structural Design Parameters on Wafer Level CSP Ball Shear Strength and Their Influence on Accelerated Thermal Cycling Reliability

2009 ◽  
Author(s):  
Nikhil Lakhkar ◽  
Puligandla Viswanadham ◽  
Dereje Agonafer
Keyword(s):  
Thermal Cycling ◽  
Shear Test ◽  
Solder Ball ◽  
Wafer Level ◽  
Ball Shear ◽  
Ball Size ◽  
Ball Shear Test ◽  
Accelerated Thermal Cycling ◽  
Ball Shear Strength ◽  
Board Level

Ball shear testing is typically conducted in Wafer level chip scale package (WLCSP) fabrication to estimate the strength of the solder ball attachment. Generally, the solder ball shear strength is dependent on the solder ball size, pad size, solder/pad interface treatment, reflow temperature and time. Solder ball strength is also a function of ram speed and height at which the ball is sheared with respect to the wafer. Recent investigations suggest that ball shear test is being used as an indicator for board level reliability of assemblies. In current market lead time for launching a new product is very short. Unfortunately, it takes several weeks to qualify a new product by board level qualification process. If there is a methodology through which one can predict the board level performance by extrapolating the wafer level test, it will save great amount of resources in testing and millions of dollars worth of testing time. In the first part of this study, we conducted a wafer level ball shear test. A DOE was created for varying wafer level structural parameters like solder ball size and type. Ball shear tests and Accelerated thermal cycling have similar failure signatures of compression on inner side and tension on outer side. Thus, for specific cases there is a possibility of correlating the two failure methodologies based on their failure signatures. Strain rate for ball shear test was determined based on shear speed and solder pad diameter. Strain rate for accelerated thermal cycling was determined based on difference in CTE between board and package. In this paper, results from ball shear test and accelerated thermal cycling are compared to find correlations for specific cases. The correlations derived from this study are statistical and empirical.

An Expedient Experimental Technique for the Determination of Thermal Cycling Fatigue Life for BGA Package Solder Balls

2007 ◽  
Vol 129 (4) ◽  
pp. 427-433 ◽  
Author(s):  
Krishna Tunga ◽  
Suresh K. Sitaraman
Keyword(s):  
Thermal Cycling ◽  
Experimental Technique ◽  
Electronic Packages ◽  
Solder Balls ◽  
Bga Package ◽  
Accelerated Thermal Cycling ◽  
Thermal Cycling Fatigue ◽  
Number Of Cycles ◽  
Thermomechanical Reliability ◽  
Ball Grid Array Packages

Although accelerated thermal cycling has been widely used in electronics industry to qualify electronic packages, efforts to reduce the time and cost associated with such qualification techniques are continuously being sought. This paper outlines a laser-moiré based experimental technique to quickly assess the thermal cycling reliability of microelectronic packages. Unlike accelerated thermal cycling that takes several months to complete, the proposed technique takes one to two weeks to complete and does not suffer from various modeling assumptions used in finite-element simulations. The developed technique has been used to determine the thermomechanical reliability of organic and ceramic ball grid array packages, and it is shown that the number of cycles determined by the proposed technique is comparable to the number of cycles determined through accelerated thermal cycling.

Temperature Dependent Viscoplastic Simulation of Controlled Collapse Solder Joint Under Thermal Cycling

1993 ◽  
Vol 115 (1) ◽  
pp. 16-21 ◽  
Author(s):  
V. Sarihan
Keyword(s):  
Thermal Cycling ◽  
Flip Chip ◽  
Strong Dependence ◽  
Inelastic Strain ◽  
Operating Conditions ◽  
Material Behavior ◽  
Time Dependent ◽  
Strong Temperature Dependence ◽  
Electronic Packages ◽  
Material Response

Solder is being extensively used in electronic packages for both electrical and mechanical connection. Solder joints are subjected to severe operating conditions and hence their reliability is very critical for the packages. Simulation is very effective for understanding, predicting and design improvement of electronic packages where solder is the prime joiner, however all the material response complexities of solder over the temperature regime it is subjected to should be modelled. Solder in electronic components very often operates at 0.6 to 0.8 times it’s melting point. In this regime the time dependent material response (creep and stress relaxation) is very significant and can no longer be ignored. Also the plastic and creep responses of solder alloys have a very strong dependence on temperature. A nonlinear finite element based methodology has been developed for simulation of solder alloy over its full regime of material behavior, also accounting for the strong temperature dependence. This includes elastic, time independent plastic, and time dependent viscoplastic response. The methodology has been used for predicting the response of a flip chip with 95Pb5 percent Sn peripheral bumps subjected to thermal cycling. Correlation is observed between the location of failure in the bump and the maximum inelastic strain. The importance of doing a multicycle simulation is demonstrated and a direction is indicated for the bump size modification for flip chip bump design improvements for greater reliability.

scholarly journals On the Plastic Strain Accumulation in Notched Bars During High-Temperature Creep Dwell

2020 ◽  
Vol 36 (2) ◽  
pp. 167-176 ◽  
Author(s):  
Daniele Barbera ◽  
Haofeng Chen
Keyword(s):  
High Temperature ◽  
Cyclic Loading ◽  
Plastic Strain ◽  
Kinematic Hardening ◽  
High Temperature Creep ◽  
Strain Accumulation ◽  
Material Models ◽  
Cyclic Loading Condition ◽  
Hardening Material ◽  
Temperature Creep

ABSTRACTStructural integrity plays an important role in any industrial activity, due to its capability of assessing complex systems against sudden and unpredicted failures. The work here presented investigates an unexpected new mechanism occurring in structures subjected to monotonic and cyclic loading at high temperature creep condition. An unexpected accumulation of plastic strain is observed to occur, within the high-temperature creep dwell. This phenomenon has been observed during several full inelastic finite element analyses. In order to understand which parameters make possible such behaviour, an extensive numerical study has been undertaken on two different notched bars. The notched bar has been selected due to its capability of representing a multiaxial stress state, which is a practical situation in real components. Two numerical examples consisting of an axisymmetric v-notch bar and a semi-circular notched bar are considered, in order to investigate different notches severity. Two material models have been considered for the plastic response, which is modelled by both Elastic-Perfectly Plastic and Armstrong-Frederick kinematic hardening material models. The high-temperature creep behaviour is introduced using the time hardening law. To study the problem several results are presented, as the effect of the material model on the plastic strain accumulation, the effect of the notch severity and the mesh element type and sensitivity. All the findings further confirm that the phenomenon observed is not an artefact but a real mechanism, which needs to be considered when assessing off-design condition. Moreover, it might be extremely dangerous if the cyclic loading condition occurs at such a high loading level.

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