Thermal Cycling Fatigue Investigation of Surface Mounted Components with Eutectic Tin-Lead Solder Joints
AffiliationCalifornia Institute of Technology
KeywordsEutectic tin-lead solder
surface mounted component (SMC)
dual in-line (DIP) package
leadless ceramic chip carrier (LCCC)
gull wing leaded quad flatpack (QFP)
J-lead leaded chip carrier
solder joint lead compliance
printed wiring board (PWB)
FR-4 epoxy/fiberglass PWB
printed wiring assembly (PWA)
solder joint failure
solder joint reliability
thermal fatigue failure
gull wing lead configuration
butt mount lead configuration
coefficient of thermal expansion (CTE)
difference in CTE
MetadataShow full item record
RightsCopyright © International Foundation for Telemetering
Collection InformationProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection.
AbstractEutectic (63% tin-37% lead) or near-eutectic (40% tin-60% lead) tin-lead solder is widely used for creating electrical interconnections between the printed wiring board (PWB) and the components mounted on the board surface. For components mounted directly on the PWB mounting pads, that is, surface mounted components, the tin-lead solder also constitutes the mechanical interconnection. Eutectic solder has a melting point of 183°C (361°F). It is important to realize that its homologous temperature, defined as the temperature in degrees Kelvin over its melting point temperature (T(m)), also in degrees Kelvin, is defined as T/T(m). At room temperature (25°C = 298K), eutectic solder's homologous temperature is 0.65. It is widely acknowledged that materials having a homologous temperature ≥ 0.5 are readily subject to creep, and the solder joints of printed wiring assemblies are routinely exposed to temperatures above room temperature. Hence, solder joints tend to be subject to both thermal fatigue and creep. This can lead to premature failures during service conditions. The geometry, that is, the lead configuration, of the joints can also affect failure. Various geometries are better suited to withstand failure than others. The purpose of this paper is to explore solder joint failures of dual in-line (DIP) integrated circuit components, leadless ceramic chip carriers (LCCCs), and gull wing and J-lead surface mount components mounted on PWBs.
SponsorsInternational Foundation for Telemetering
Showing items related by title, author, creator and subject.
Coupled thermal and vibration numerical analysis of solder jointsDesai, Chandrakant S.; Nickerson, Mark David (The University of Arizona., 2002)A heat transfer subroutine has been implemented into an existing finite element code developed in theCivil Engineering and Engineering Mechanics Department at the University of Arizona by Dr. Desai and students. The code is capable of performing non linear material and dynamic analysis. The heat transfer subroutine has been implemented such that any inelastic material behavior induced by a temperature increment is captured at every time step in a loading cycle. With the addition of the heat transfer routine, both thermal sources and sinks can be modeled. For example, power generating chips and power dissipating heat sinks, respectively. This will allow a more realistic representation of electronic packages under operational conditions. A 313 ball PBGA staggered area array package was used in all the analyses performed in this dissertation. The calibration of the models was based on research performed by the JPL consortium which included members such as Raytheon, Boeing and Xilinx. The focus of this dissertation was to determine the thermal and vibration fatigue lifetimes of electronic packages using the Disturbed State Concept. To achieve this goal, numerous analyses were performed, representing different test cases. The different test cases included thermal test chamber cycling (TCT), power cycling (PCT), vibration, thermal test chamber cycling with voids in solder balls, vibration with voids in solder balls, and coupled temperature with vibration. Based on the results of these analyses, the Disturbed State Concept was found to predict the fatigue lifetimes of the 313 PBGA package with excellent accuracy, when test results were available for comparison.
Cracked Solder Joint Mechanism in Discrene Component AssembliesEstes, H. P.; Theobald, P. E. (International Foundation for Telemetering, 1968-10)Solder joint cracking has occurred in assemblies where discrete part subassemblies are fabricated on Printed Circuit Boards and conformal coating is applied to the sub-assembly. The objective of the investigation were to determine the extent and seriousness of the problem, to determine the cracking mechanism, and to provide engineering and process information to eliminate the problem. The analysis and test results indicate that many factors influence the strength of a solder joint and the ultimate crack that develops. Contamination by gold products and other foreign materials can significantly affect solder characteristics. Aging and temperatures experienced in the normal operating range of certain equipment adversely affects the strength of the solder materials. Conformal coating between the discrete part and the Printed Circuit Board is a major contributor to the cracking mechanism. Transistor assemblies using a Spacer under the TO-5 enclosure with Kovar Lead Material and completely covered with conformal coating have a high incidence of cracked solder joints. This condition is caused by the mis-match of coefficients of expansion between the Kovar Lead and the conformal coating.
Characterization and comparison of creep properties for tin-indium-silver solder jointsJackson, Kenneth A.; Seddon, Michael John, 1971- (The University of Arizona., 1996)In the search of a lead-free solder for use as a replacement of the current tin/lead solders, an alloy consisting of 77.2% tin, 20% indium, and 2.8% silver has been invented. This solder, entitled Indalloy #227, has demonstrated bulk properties comparable to tin/lead solders. Further characterization of this alloy was completed in this research by determining the steady state creep rate properties of actual solder joints. The solder joints were formed using ceramic substrates with gold/nickel/copper and copper pad metallizations. The fabrication process of the samples was optimized to yield the highest shear strength. Creep properties were determined at temperatures ranging from -40°C to 125°C using a set of grips which subjected the samples to pure shear stresses. The activation energy was determined, and a comparison of the creep rates was then made to five other solders. Results from this comparison showed that the 77.2Sn/20.0In/2.8Ag solder demonstrates creep properties similar to those of typical tin/lead solders.