Fundamental adhesion issues for advanced flip chip packaging

Tong, Q.K.; Ma, B.; Xiao, A.Y.; Savoca, A.; Luo, Shijian; Wong, Ching‐Ping

doi:10.1109/ectc.2002.1008285

Cited by 16 publications

(6 citation statements)

References 19 publications

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“…LCP consists of several different layers where the outer part is called injection molded skin with a thickness of few microns. The adhesive strength of the skin to the next inner layer is weak, Dreßler et al (2006a), Schledjewski and Friedrich (1992), Tong et al (2002). This is clearly seen in Fig.…”

Section: Experimental Realization and Testingmentioning

confidence: 80%

Application of interfacial fracture mechanics approach for obtaining design rules for flip chip interconnections

et al. 2008

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The reliability of an electronic package can be described by a physics-of-failure approach. Crack initiation and propagation in the bulk material and interface leads to catastrophic mechanical and finally to electrical failure. Therefore, bulk and interfacial fracture mechanics is a suitable method to describe the reliability of an electronic package. As package, a stud bump bonding flip chip interconnection on a thermoplastic substrate material [liquid crystal polymer (LCP)] is studied. The paper focuses on the description of the interfacial cracking between the underfill and the LCP. This is used to obtain design rules for flip chip interconnection on LCP by means of finite element analysis. Geometry design parameters-fillet shape, chip and substrate sizes-are studied. Moreover, the influence of material properties of the substrate and underfill are investigated. The impacts of the parameters are evaluated by analyzing the energy release rate (ERR) and mode-mixity in the interface. For determination of the critical ERR as function of the mode-mixity, a modified button shear test is utilized. The button, made out of underfill, is cured on the LCP substrate. A pre-delamination is established using a Teflon strip. The critical ERR for different mode-mixities is obtained by varying the shearing height of the button test. Additional, the influence of oxygen plasma treatment of the LCP substrate on the interfacial cracking is taken into account. In the investigation, design rules for increasing the reliability of flip chip interconnections are obtained. Moreover, a modified button-test is applied to obtain critical energy releases rates for different mode-mixities for the interface underfill/LCP. These results are used to optimize the geometry and materials of flip chip interconnections for automotive sensor applications in respect to delamination risk between substrate and underfill

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Section: Experimental Realization and Testingmentioning

confidence: 80%

Application of interfacial fracture mechanics approach for obtaining design rules for flip chip interconnections

et al. 2008

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“…Therefore, a low contact angle would indicate a clean and/or wettable surface [3,[13][14][15]. Although enhanced wetting aids in spreading of adhesive onto the substrate for better bonding, the practical adhesion may not always be correlated with wettability [7,15]. Hence both contact angle and adhesion tests were used for plasma optimization in this study.…”

Section: A Contact Angle Analysis and Adhesion Testmentioning

confidence: 99%

Plasma Surface Modification and Impact on MSL Performance for Flip Chip Packaging

Teo

Lee

Chew

et al. 2007

2007 9th Electronics Packaging Technology Conference

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The effectiveness of "under-chip" plasma cleaning and its impact on moisture sensitivity level (MSL) performance for flip chip packaging was investigated in this study. A customized test vehicle was designed for surface analysis on the flip chip silicon nitride (SiN) passivation and substrate solder mask surfaces. Optimization of the plasma conditions was achieved using contact angle measurement, adhesion testing, and verified with X-ray Photoelectron Spectroscopy (XPS), Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) analysis. The impact of plasma cleaning on MSL performance was assessed using a molded flip chip in package (FCIP) test vehicle. It was found that significant adhesion enhancement of SiN passivation to underfill can be achieved by a synergistic combination of the following plasma surface modifications: removal of organic contaminants, formation of certain functional groups (C=O, O-C-O and O-C=O), and an increase in effective surface area. In summary, this study has demonstrated the benefits of an optimized "under-chip" plasma cleaning process for MSL performance improvement of a molded FCIP. Findings from this extensive plasma characterization also enable a better understanding on how plasma surface modification can contribute towards packaging of more robust products.

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“…14,15 Extensive studies on the adhesion features of underfill/die passivation/die and the reliability of solder bumps have been made. 3,10,11,16 In addition, some researchers have begun to investigate the influence of thermal cycling on the adhesion strength of underfill/die passivation/die interfaces, and the corresponding failure mechanisms. 17,18 However, information on the thermomechanical behavior of the underfill/solder mask/substrate adhesion is still insufficient, especially as related to thermal fatigue.…”

Section: Introductionmentioning

confidence: 99%

Thermomechanical behavior of underfill/solder mask/substrate interface under thermal cycling

Chien

Chen

Hsieh

et al. 2004

Experimental Mechanics

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ABSTRACT--With the increasing application of flip-chip technology in the microelectronics industry, the adhesion strength of interfaces in flip-chip microelectronic structures has become an important issue for manufacturing and operation. In this paper we present an experimental investigation of the adhesive strength of underfill material to solder mask coated FR-4 substrate under thermal cycling. The effects of the number of thermal cycles on interfacial strength were investigated by using the button shear test.The relationship between interfacial strength and the thickness of solder mask was also examined. Furthermore, the morphologies of fracture surfaces of the test specimens were analyzed by scanning electron microscopy. The results of this study show that the interracial strength of the underfill/solder masldsubstrate joint was significantly reduced by thermal fatigue. Finally, the degradation behavior and possible mechanisms were then determined on the basis of these observations.

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Fundamental adhesion issues for advanced flip chip packaging

Cited by 16 publications

References 19 publications

Application of interfacial fracture mechanics approach for obtaining design rules for flip chip interconnections

Application of interfacial fracture mechanics approach for obtaining design rules for flip chip interconnections

Plasma Surface Modification and Impact on MSL Performance for Flip Chip Packaging

Thermomechanical behavior of underfill/solder mask/substrate interface under thermal cycling

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