Hygro-Thermal Warpages of COG Package With Nonconductive Paste Adhesive

Tsai, Ming-Yi; Huang, Chenyu; Chiang, Chih-Yao; Chen, Wen-Chin; Yang, Shang-Shyng

doi:10.1109/tcapt.2007.898691

Cited by 3 publications

(3 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Differentiating the equation (23) twice with respect to the coordinate x, the following equation for the peeling stress function p(x) can be obtained: (24) where the notation (25) is used. The equation (24) has the form of the equation of bending of a beam supported by a continuous elastic foundation (which, KRZHYHU GHWHUPLQHV WKH GHÀHFWLRQV QRW WKH VWUHVV DQG WKHUHIRUH LWV solution can be sought in the form [48]: (26) Here is the characteristic of the level of the peeling stress in comparison with the shearing stress, the functions V i (ȕ[), i = 0,1,2,3, are expressed as (27) and obey the following simple and convenient rules of differentiation: (28) 7KH ¿UVW WZR WHUPV LQ (26) is the general solution to the homogeneous equation that can be obtained from (26) by putting its right part equal to zero, and the last term is the particular solution to the inhomogeneous equation (26). The constants (29) of integration can be found from the boundary conditions (30) The notation u = ȕO is used in the formulas (29).…”

Section: Peeling Stressmentioning

confidence: 99%

“…In the practically important case of an elongated assembly with stiff interfaces (large u = ȕO values) the formulas (29) FDQ EH VLPSOL¿HG (32) Then the solution (26) results in the following expression for the distributed peeling stress: (33) 7KH ¿UVW WHUP LQ WKH EUDFNHWV FRQVLGHUV WKH GLUHFW LPSDFW RI WKH interfacial shearing stress, and the second term is the response of the assembly to the longitudinal gradient of the interfacial shearing load. At the assembly ends (x = l) (34) When the parameter Ș UHÀHFWLQJ WKH UHODWLYH UROHV RI WKH LQWHUIDFLDO SHHOLQJ DQG VKHDULQJ LQWHUIDFLDO VWUHVVHV LV VLJQL¿FDQW WKH IRUPXOD (34) yields: p(l) = p 0 .…”

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%

See 2 more Smart Citations

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

Suhir¹,

Bensoussan²,

Nicolics³

2015

SAE Technical Paper Series

View full text Add to dashboard Cite

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...

show abstract