The integrated theory of whisker formation - a stress analysis

Galyon, G.T.; Xu, Caixia; Lai, Si Yu; Notohardjono, B.; Palmer, Larry

doi:10.1109/ectc.2005.1441299

Cited by 7 publications

(4 citation statements)

References 7 publications

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“…There is significant work already defending this statement starting as early as the 1950s [32]. More recently, at ECTC 2005, Galyon et al [21] published an excellent overview of compressive stress at it relates to whisker growth and also presented a "to be published" detailed work evaluating and refuting claims of whisker growth without compressive stress. Fig.…”

Section: A Initial and Necessary Conditions For Whisker Growthmentioning

confidence: 95%

Theory of Tin Whisker Growth: “The End Game”

Smetana¹

2007

IEEE Trans. Electron. Packag. Manufact.

127

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Previous theories of the tin whisker growth proposing various dislocation mechanisms have been largely disproved. This paper presents a new and different theory for the mechanism of tin whisker growth. The theory addresses the fundamental requirements for Sn to diffuse to the base of the whisker grain and proposes a mechanism for whisker initiation and growth. Part of this is a theoretical proposal as to what makes the whisker grain different. The role of oxidation in whisker growth is also briefly addressed. Using this theory, attempts are made to illustrate how different whisker shapes are created. Finally, a proposed potential solution to tin whisker growth is presented, assuming that this theory is correct.

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Section: A Initial and Necessary Conditions For Whisker Growthmentioning

confidence: 95%

Theory of Tin Whisker Growth: “The End Game”

Smetana¹

2007

IEEE Trans. Electron. Packag. Manufact.

127

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“…They also proliferate greatly to form bands that support axon growth into and through distal nerve stumps. This support includes supplying numerous growth factors and extracellular matrix secretion [13,23,25,27,33]. Experimentally, SCs transplantation has been shown to enhance axon outgrowth both in vitro [51] and in vivo [7,32].…”

Section: Introductionmentioning

confidence: 99%

A comparison of the use of adipose-derived and bone marrow-derived stem cells for peripheral nerve regeneration in vitro and in vivo

Zhou

Wang

et al. 2020

Stem Cell Res Ther

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Background: To date, it has repeatedly been demonstrated that infusing bone marrow-derived stem cells (BMSCs) into acellular nerve scaffolds can promote and support axon regeneration through a peripheral nerve defect. However, harvesting BMSCs is an invasive and painful process fraught with a low cellular yield. Methods: In pursuit of alternative stem cell sources, we isolated stem cells from the inguinal subcutaneous adipose tissue of adult Sprague-Dawley rats (adipose-derived stem cells, ADSCs). We used a co-culture system that allows isolated adult mesenchymal stem cells (MSCs) and Schwann cells (SCs) to grow in the same culture medium but without direct cellular contact. We verified SC phenotype in vitro by cell marker analysis and used red fluorescent protein-tagged ADSCs to detect their fate after being injected into a chemically extracted acellular nerve allograft (CEANA). To compare the regenerative effects of CEANA containing either BMSCs or ADSCs with an autograft and CEANA only on the sciatic nerve defect in vivo, we performed histological and functional assessments up to 16 weeks after grafting. Results: In vitro, we observed reciprocal beneficial effects of ADSCs and SCs in the ADSC-SC co-culture system. Moreover, ADSCs were able to survive in CEANA for 5 days after in vitro implantation. Sixteen weeks after grafting, all results consistently showed that CEANA infused with BMSCs or ADSCs enhanced injured sciatic nerve repair compared to the acellular CEANA-only treatment. Furthermore, their beneficial effects on sciatic injury regeneration were comparable as histological and functional parameters evaluated showed no statistically significant differences. However, the autograft group was roundly superior to both the BMSC-or ADSC-loaded CEANA groups. Conclusion: The results of the present study show that ADSCs are a viable alternative stem cell source for treating sciatic nerve injury in lieu of BMSCs.

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“…According to Laurila et al [46], the reaction rate of the Ni-Sn is relatively smaller than the Cu-Sn, thus resulting in a thinner IMC layer in the Ni-Sn. Other researchers also agreed that the reaction rate of Ni-Sn is slower compared to the reaction rate of the Cu-Sn [47,48]. Thus, the Ni layer acts effectively as a barrier layer for the immersion tin surface finish to prevent the formation of Cu-Sn intermetallics, which is believed to be the main factor for whiskers' formation and growth.…”

Section: Influence Of Inter-diffusionmentioning

confidence: 98%

Tin Whiskers’ Behavior under Stress Load and the Mitigation Method for Immersion Tin Surface Finish

et al. 2021

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Since the use of the most stable Pb-based materials in the electronic industry has been banned due to human health concerns, numerous research studies have focused on Pb-free materials such as pure tin and its alloys for electronic applications. Pure tin, however, suffers from tin whiskers’ formation, which tends to endanger the efficiency of electronic circuits, and even worse, may cause short circuits to the electronic components. This research aims to investigate the effects of stress on tin whiskers’ formation and growth and the mitigation method for the immersion of the tin surface’s finish deposited on a copper substrate. The coated surface was subjected to external stress by micro-hardness indenters with a 2N load in order to simulate external stress applied to the coating layer, prior to storage in the humidity chamber with environmental conditions of 30 °C/60% RH up to 52 weeks. A nickel underlayer was deposited between the tin surface finish and copper substrate to mitigate the formation and growth of tin whiskers. FESEM was used to observe the whiskers and EDX was used for measuring the chemical composition of the surface finish, tin whiskers, and oxides formed after a certain period of storage. An image analyzer was used to measure the whiskers’ length using the JEDEC Standard (JESD22-A121A). The results showed that the tin whiskers increased directly proportional to the storage time, and they formed and grew longer on the thicker tin coating (2.3 μm) than the thin coating (1.5 μm). This is due to greater internal stress being generated by the thicker intermetallic compounds identified as the Cu5Sn6 phase, formed on a thicker tin coating. In addition, the formation and growth of CuO flowers on the 1.5 μm-thick tin coating suppressed the growth of tin whiskers. However, the addition of external stress by an indentation on the tin coating surface showed that the tin whiskers’ growth discontinued after week 4 in the indented area. Instead, the whiskers that formed were greater and longer at a distance farther from the indented area due to Sn atom migration from a high stress concentration to a lower stress concentration. Nonetheless, the length of the whisker for the indented surface was shorter than the non-indented surface because the whiskers’ growth was suppressed by the formation of CuO flowers. On the other hand, a nickel underlayer successfully mitigated the formation of tin whiskers upon the immersion of a tin surface finish.

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The integrated theory of whisker formation - a stress analysis

Cited by 7 publications

References 7 publications

Theory of Tin Whisker Growth: “The End Game”

Theory of Tin Whisker Growth: “The End Game”

A comparison of the use of adipose-derived and bone marrow-derived stem cells for peripheral nerve regeneration in vitro and in vivo

Tin Whiskers’ Behavior under Stress Load and the Mitigation Method for Immersion Tin Surface Finish

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The integrated theory of whisker formation - a stress analysis

Cited by 7 publications

References 7 publications

Theory of Tin Whisker Growth: &ldquo;The End Game&rdquo;

Theory of Tin Whisker Growth: &ldquo;The End Game&rdquo;

A comparison of the use of adipose-derived and bone marrow-derived stem cells for peripheral nerve regeneration in vitro and in vivo

Tin Whiskers’ Behavior under Stress Load and the Mitigation Method for Immersion Tin Surface Finish

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Theory of Tin Whisker Growth: “The End Game”

Theory of Tin Whisker Growth: “The End Game”