Development of process modeling methodology for flip chip on flex interconnections with non-conductive adhesives

2005 ◽  
Vol 45 (7-8) ◽  
pp. 1215-1221 ◽  
Author(s):  
Xiaowu Zhang ◽  
E.H. Wong ◽  
Ranjan Rajoo ◽  
Mahadevan K. Iyer ◽  
J.F.J.M. Caers ◽  
...  
Keyword(s):  
Process Modeling ◽  
Flip Chip ◽  
Conductive Adhesives ◽  
Modeling Methodology

Development of Integrated Process-Ageing Modeling Methodology for Flip Chip on Flex Interconnections With Non-Conductive Adhesives

2005 ◽  
Author(s):  
Xiaowu Zhang ◽  
E. H. Wong ◽  
Ranjan Rajoo ◽  
Mahadevan K. Iyer ◽  
J. F. J. M. Caers ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Mechanical Stress ◽  
Flip Chip ◽  
Process Condition ◽  
Integrated Process ◽  
Conductive Adhesives ◽  
Element Modeling ◽  
Ageing Test ◽  
Modeling Methodology

This paper presents a comprehensive methodology to model the static temperature-humidity (TH) ageing test (85°C/85%RH over 1000 hours) of flip chip on flex interconnections with non-conductive adhesives (NCAs). Nonconductive adhesives, being a special form of conductive adhesives, are chosen, as they allow bringing the pitch further down. The methodology combines experimental techniques for material characterization, finite element modeling (FEM) and model validation. A non-conductive adhesive (NCA) has been characterized using several techniques. The thermomechanical properties and the moisture properties were obtained for the NCA. A temperature dependent viscoelastic constitutive model was also obtained for the NCA. The viscoelastic model was defined by the Prony series expansion. The shift factor was approximated by the Williams-Landel-Ferry (WLF) equation. Finite element modeling has been performed to analyze the flip chip interconnects on flex with the NCA under process condition and reliability ageing conditions. The viscoelastic constitutive relation has been used to model the NCA in ageing modeling. An integrated process-ageing modeling methodology has been developed to combine the thermo-mechanical stress and hygro-mechanical stress, followed by stress relaxation analysis. To verify the finite element models, the static TH ageing test (85°C/85%RH) were also performed. The contact resistance was monitored with high measuring resolution during the accelerated test. The simulation results are good agreement with the experimental results. The approach developed in this paper can be used to provide guidelines with respect to adhesive material properties, assembly process parameters and good reliability performances.

Evaluation of area bonding conductive adhesives for flip chip attach of area bonded die

2002 ◽  
Author(s):  
J.M. Czarnowski ◽  
M.E.S. Reynolds ◽  
M.T. Hayes ◽  
C.D. Ellis ◽  
R.W. Johnson ◽  
...  
Keyword(s):  
Flip Chip ◽  
Conductive Adhesives

Evaluation of a Conductive Adhesive Based Approach to Lead Free Flip Chip Assembly

2002 ◽  
Author(s):  
Muthiah Venkateswaran ◽  
Peter Borgesen ◽  
K. Srihari
Keyword(s):  
High Speed ◽  
Flip Chip ◽  
Printed Circuit Board ◽  
Critical Evaluation ◽  
Conductive Adhesive ◽  
Circuit Board ◽  
Lead Free ◽  
Conductive Adhesives ◽  
Flip Chip Assembly ◽  
Placement Machine

Electrically conductive adhesives are emerging as a lead free, flux less, low temperature alternative to soldering in a variety of electronics and optoelectronics applications. Some of the potential benefits are obvious, but so far the adhesives have some limitations as well. The present work offers a critical evaluation of one approach to flip chip assembly, which lends itself particularly well to use with a high speed placement machine. Wafers were bumped by stencil printing of a thermoset conductive adhesive, which was then fully cured. In assembly, the conductive adhesive paste was stencil printed onto the pads of a printed circuit board and cured after die placement. The printing process was optimized to ensure robust assembly and the resulting reliability assessed.

Reliability Investigation for Encapsulated Isotropic Conductive Adhesives Flip Chip Interconnection

2005 ◽  
Vol 128 (3) ◽  
pp. 177-183 ◽  
Author(s):  
Liu Caroline Chen ◽  
Zonghe Lai ◽  
Zhaonian Cheng ◽  
Johan Liu
Keyword(s):  
Flip Chip ◽  
Fem Simulation ◽  
Lifetime Measurement ◽  
Elastic Model ◽  
Conductive Adhesives ◽  
Electronic Manufacturing ◽  
Thermal Fatigue Life ◽  
Isotropic Conductive Adhesives ◽  
Product Lifetime ◽  
Chip Size

Isotropic conductive adhesives (ICA) are gaining more and more application interests in electronic manufacturing, however, their failure mechanism is not been fully understood. In this paper we present reliability investigations on an encapsulated ICA flip chip interconnection. Experimental work included product lifetime measurement, cross section observation, and whole module warpage scanning. Results revealed that the chip-size effect on the ICA lifetime was obvious. A theoretical analysis was conducted with Finite Element Method (FEM) simulation. Viscoelastic models for adhesives and underfill materials were employed, and the comparison with an elastic model was made. Calculated equivalent stresses Seqv and shear stress σxy fitted well with the experimental lifetime measurement, thus a lifetime relationship similar to the Coffin-Manson formula was established to predict the thermal fatigue life of an encapsulated ICA flip chip. Furthermore, the influences of underfill properties on the ICA reliability were discussed.

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