Study of Dynamic Warpage of Flip Chip Packages under Temperature Reflow

Lee, Chee Kan; Loh, Wei Keat; Ong, Kang Eu; Chin, IR

doi:10.1109/iemt.2006.4456453

Cited by 7 publications

(3 citation statements)

References 2 publications

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“…[4]), and large non-molded flipchip-BGAs (e.g. [5]). Some studies were published on large, thick PBGA packages (typically 1.7 mm and larger package body thickness, e.g.…”

Section: Introductionmentioning

confidence: 99%

Warpage measurements of laminate based BGA packages at elevated temperatures and comparison with real board assembly behaviour

Birzer

Graml

Dittes

et al. 2008

2008 33rd IEEE/CPMT International Electronics Manufacturing Technology Conference (IEMT)

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This paper is about warpage of laminate substrate based BGAs and fine pitch BGAs at lead-free board assembly reflow temperatures using shadow moiré technique. Various constructions (e.g. single die devices and multi chip modules) and different die and package sizes as well as different molding compound materials were considered in this study. A simple model for predicting high temperature warpage for single die devices based on the distance between package corner and die corner was developed. The comparison of the warpage results with and without moisture soaking according JEDEC MSL 3 did not exhibit a significant influence on high temperature warpage. The shadow moiré test results at elevated temperatures are compared with solder joint height distributions measured in cross sections after real lead-free board assembly. A clear correlation of the solder joint height distributions with the package warpage status at 170 °C during cooling phase was found. This is much lower than the mominal solidification temperature of lead-free solder. This study helps to understand the influencing factors of BGA warpage and its role for board assembly.

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“…[4]), and large non-molded flipchip-BGAs (e.g. [5]). Some studies were published on large, thick PBGA packages (typically 1.7 mm and larger package body thickness, e.g.…”

Section: Introductionmentioning

confidence: 99%

Warpage measurements of laminate based BGA packages at elevated temperatures and comparison with real board assembly behaviour

Birzer

Graml

Dittes

et al. 2008

2008 33rd IEEE/CPMT International Electronics Manufacturing Technology Conference (IEMT)

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“…Treating an outer component of the assembly as a thin elongated plate, the following equation of its equilibrium can be applied: (21) The left part of this equation is the elastic bending moment, where (22) LV WKH ÀH[XUDO ULJLGLW\ RI WKH FRPSRQHQW 7KH ¿UVW WHUP LQ WKH ULJKW part of (21) is the external bending moment caused by the thermally induced force T(x) and the second term is the bending moment due to the peeling stress. Considering the relationship (19) and the equilibrium equation (21), the following equation for the peeling stress can be obtained: (23) Here is the parameter of the peeling stress, which is similar to the parameter (10) of the interfacial shearing stress.…”

Section: Peeling Stressmentioning

confidence: 99%

“…Ability to predict and minimize warpage is critical for the product fabrication (soldering requirements and assembly) and operation [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35]. Warpage is affected by package geometries, properties of the molding compound, mechanical characteristics of the employed materials and, certainly, the direction and level of temperature excursions.…”

Section: Introduction ([Fhvvlyh Zdusdjh Erz LV D Vljql¿fdqw Frqfhuq Rmentioning

confidence: 99%

Bow-Free Tri-Component Mechanically Pre-Stressed Failure-Oriented-Accelerated-Test (FOAT) Specimen

Suhir¹,

Bensoussan²,

Nicolics³

2015

SAE Technical Paper Series

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OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an author-deposited version published in : http://oatao.univ-toulouse.fr/ Eprints ID : 18140 Any correspondence concerning this service should be sent to the repository administrator: staff-oatao@listes-diff.inp-toulouse.fr AbstractIn some today's and future electronic and optoelectronic packaging systems (assemblies), including those intended for aerospace applications, the package (system's component containing active and passive devices and interconnects) is placed (sandwiched) between two substrates. In an approximate stress analysis these substrates could be considered, from the mechanical (physical) standpoint, identical. Such assemblies are certainly bow-free, provided that all the stresses are within the elastic range and remain elastic during testing and operation. Ability to remain bow-free is an important merit for many applications. This is particularly true in optical engineering, where there is always a QHHG WR PDLQWDLQ KLJK FRXSOLQJ HI¿FLHQF\ The level of thermal stresses in bow-free assemblies of the type in question could be, however, rather high. High thermal stresses are caused by the thermal contraction mismatch of the dissimilar materials of the assembly components and occur at low temperature conditions. These stresses include normal stresses acting in the component cross-sections and interfacial shearing and peeling stresses. The normal stresses in the component cross-sections determine the reliability of the component materials and the devices embedded into the inner component (package). The interfacial stresses affect the adhesive and cohesive strength of the assembly, i.e. its integrity.It should be pointed out that although the assembly as a whole is bow-free, the peeling stresses in it, whether thermal or mechanical, are not necessarily low: the two outer components (substrates) might exhibit appreciable warpage with respect to the bow-free inner component (package).While there is an incentive for using bow-free assemblies, there is also an incentive for narrowing the temperature range of the accelerated reliability testing: elevated temperature excursions might produce an undesirable shift in the modes and mechanisms of failure, i.e. lead to failures that will hardly occur in actual operation conditions. Failure oriented accelerated test (FOAT) specimens are particularly vulnerable, since the temperature range in these tests should be broad enough to lead to a failure, and, if a shift in the PRGHV DQG PHFKDQLVPV RI IDLOXUHV WDNHV SODFH GXULQJ VLJQL¿FDQW temperature excursions, the physics of such failures might be quite different of those in actual operation conditions. Mechanical pre-stressing can be an effective means for narrowing the range of temperature excursions during accelerated testing and, owing to that, -for obtaining consistent and trustworthy information. If prestressing is considered, the ability to predict the thermo-mech...

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Predicted thermal stresses in a bow-free electronic assembly for automotive and potential aerospace applications

Suhir

Nicolics

Béchou

2016

2016 IEEE Aerospace Conference

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Study of Dynamic Warpage of Flip Chip Packages under Temperature Reflow

Cited by 7 publications

References 2 publications

Warpage measurements of laminate based BGA packages at elevated temperatures and comparison with real board assembly behaviour

Warpage measurements of laminate based BGA packages at elevated temperatures and comparison with real board assembly behaviour

Bow-Free Tri-Component Mechanically Pre-Stressed Failure-Oriented-Accelerated-Test (FOAT) Specimen

Predicted thermal stresses in a bow-free electronic assembly for automotive and potential aerospace applications

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