Board level BGA and CSP Underfill - diagnostic methods and the potential of using a tensile test and subsequent optical microscopy

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68407700%3A21230%2F25%3A00383944" target="_blank" >RIV/68407700:21230/25:00383944 - isvavai.cz</a>

Result on the web

<a href="https://doi.org/10.1016/j.polymertesting.2025.108872" target="_blank" >https://doi.org/10.1016/j.polymertesting.2025.108872</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.polymertesting.2025.108872" target="_blank" >10.1016/j.polymertesting.2025.108872</a>

Result language

angličtina

Original language name

Board level BGA and CSP Underfill - diagnostic methods and the potential of using a tensile test and subsequent optical microscopy

Original language description

Reducing the dimensions of Ball Grid Array (BGA) and Chip Scale Package (CSP) components in electronics design and manufacturing presents challenges similar to packages with flip-chips during temperature cycling. Therefore, underfill technology is increasingly used at the board level to enhance the durability of soldered joints in these components and improve the overall reliability of devices. However, a key issue with underfill is the limited quality control options and diagnostic methods available to assess its impact on specific assemblies. This work highlights the application of different diagnostic methods already established in other fields of electrical engineering, emphasizing the advantages of tensile testing combined with three-dimensional optical microscopy. The work results show that although underfill generally enhances the mechanical properties of the assembly, its effects vary significantly between components, so each component needs individual examination. Furthermore, Kernel Density Estimation analysis revealed significant differences in solder joint distribution layout between the components, correlating with their observed mechanical responses. Mechanical stress, Young modulus and toughness were investigated, while the latter appears to be the most suitable for comparing the influence of underfill on assemblies and individual components. The underfilled CSP component showed a 34 % increase in toughness compared to the non-underfilled, while the BGA component showed an increase of 94 %. The CSP component demonstrated a noticeable trend: toughness increased by 20 % from 0 to 2000 temperature cycles but then experienced a decline of 24 % at 3000 temperature cycles. This trend is not apparent for the BGA component. The combination of tensile testing with optical microscopy proves to be an effective method for evaluating the effect of underfill, detecting the weakest parts of the assembly and possibly optimizing its use for various types of BGA and CSP components.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

20201 - Electrical and electronic engineering

Project

—

Continuities

S - Specificky vyzkum na vysokych skolach

Publication year

2025

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Polymer Testing

ISSN

0142-9418

e-ISSN

1873-2348

Volume of the periodical

149

Issue of the periodical within the volume

149

Country of publishing house

NL - THE KINGDOM OF THE NETHERLANDS

Number of pages

16

Pages from-to

1-16

UT code for WoS article

001504012400001

EID of the result in the Scopus database

2-s2.0-105006878975