Capillary-driven micro flows for the underfill process in microelectronics packaging

Kim, Young Bae; Sung, Jaeyong

doi:10.1007/s12206-012-1001-7

Cited by 25 publications

(6 citation statements)

References 23 publications

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“…Although this dispensing method is the quickest, it is also the one that will raise the most racing effect as the epoxy is being applied one at a time rather than simultaneously across the three sides. The region that is prone to form a void is also the place where the BGA is broadly spaced out, creating a larger empty area and exacerbating the racing effect stated by Kim and Sung (2013), who noted that the inconsistent capillary spacing between the solder balls would cause extended filling time that leads to incomplete filling, hence forming a void. In addition, the TSAM sample is measured for the void percentage found.…”

Section: Resultsmentioning

confidence: 99%

Deep learning and analytical study of void regional formation in flip-chip underfilling process

Ling,

Azahari,

Abas

et al. 2023

SSMT

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Purpose This paper aims to study the relationship between the ball grid array (BGA) flip-chip underfilling process parameter and its void formation region. Design/methodology/approach A set of top-down scanning acoustic microscope images of BGA underfill is collected and void labelled. The labelled images are trained with a convolutional neural network model, and the performance is evaluated. The model is tested with new images, and the void area with its region is analysed with its dispensing parameter. Findings All findings were well-validated with reference to the past experimental results regarding dispensing parameters and their quantitative regional formation. As the BGA is non-uniform, 85% of the test samples have void(s) formed in the emptier region. Furthermore, the highest rating factor, valve dispensing pressure with a Gini index of 0.219 and U-type dispensing pattern set of parameters generally form a lower void percentage within the underfilling, although its consistency is difficult to maintain. Practical implications This study enabled manufacturers to forecast the void regional formation from its filling parameters and array pattern. The filling pressure, dispensing pattern and BGA relations could provide qualitative insights to understand the void formation region in a flip-chip, enabling the prompt to formulate countermeasures to optimise voiding in a specific area in the underfill. Originality/value The void regional formation in a flip-chip underfilling process can be explained quantitatively with indicative parameters such as valve pressure, dispensing pattern and BGA arrangement.

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Section: Resultsmentioning

confidence: 99%

Deep learning and analytical study of void regional formation in flip-chip underfilling process

Ling,

Azahari,

Abas

et al. 2023

SSMT

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“…Despite handful amount underfill researches being conducted to optimize and improve the process's productivity and later package's reliability, the comprehensive literature reviews on underfill works are still limited. There are only four review works related to the underfill encapsulation process being reported to date [2,3,6,7], as listed in Table 1. However, these reviews rather focused on a niche and narrow scopes.…”

Section: Introductionmentioning

confidence: 99%

Underfill Flow in Flip-Chip Encapsulation Process: A Review

Abas

2021

Journal of Electronic Packaging

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The scope of review of this paper focused on the pre-curing underfilling flow stage of encapsulation process. A total of 80 related works has been reviewed and being classified into process type, method employed, and objective attained. Statistically showed that the conventional capillary is the most studied underfill process, while the numerical simulation was mainly adopted. Generally, the analyses on the flow dynamic and distribution of underfill fluids in the bump array aimed for the filling time determination as well as the predictions of void occurrence. Parametric design optimization was subsequently conducted to resolve the productivity issue of long filling time and reliability issue of void occurrence. The bump pitch was found to the most investigated parameter, consistent to the miniaturization demand. To enrich the design versatility and flow visualization aspects, experimental test vehicle was innovated using imitated chip and replacement fluid, or even being scaled-up. Nonetheless, the analytical filling time models became more accurate and sophiscasted over the years, despite still being scarce in number. With the technological advancement on analysis tools and further development of analytic skills, it was believed that the future researches on underfill flow will become more comprehensive, thereby leading to the production of better packages in terms of manufacturing feasibility, performances, and reliability. Lastly, few potential future works were recommended, for instance, microscopic analysis on the bump-fluid interaction, consideration of filler particles and incorporation of artificial intelligence.

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“…Many studies on the capillary flow phenomenon, viscosity, thixotropic properties, and wettability have been reported. 2,3) However, because the capillary flow type encapsulate technology requires a large number of processes, pre-mount-type no-flow underfill resin materials have been developed. 4,5) Shape retention ability on the substrate is essential for the no-flow underfill resins.…”

Section: Introductionmentioning

confidence: 99%

Development of Polyester-Modified Epoxy Resins for Self-Organization Soldering

et al. 2019

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Novel underfill resins combining a thermoset epoxy resin with thermoplastic polyester resins have been developed for self-organization soldering. Polyester-modified epoxy resins, which are hybrid resins, exhibited minimal viscosity at the melting point of the Sn58 mass%Bi solder, with the viscosity dependent on the content and molecular mass of the blended polyester resin. Because the epoxy resin was sufficiently compatible with the polyester resin in the hybrid, the curing reaction of the hybrid resin was similar to that of the epoxy resin. The chemical structure of the polyester resin was retained in the cured hybrid resin, imparting thermoplasticity to the hybrid resins cured with repeated heating. Successful self-organization soldering was achieved using the developed hybrid-resin-based solder paste. [

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Capillary-driven micro flows for the underfill process in microelectronics packaging

Cited by 25 publications

References 23 publications

Deep learning and analytical study of void regional formation in flip-chip underfilling process

Deep learning and analytical study of void regional formation in flip-chip underfilling process

Underfill Flow in Flip-Chip Encapsulation Process: A Review

Development of Polyester-Modified Epoxy Resins for Self-Organization Soldering

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