Acceleration measurements during reactive bonding processes

Spies, Irina; Schumacher, Axel; Knappmann, S.; Rheingans, Bastian; Janczak‐Rusch, Jolanta; Jeurgens, Lars P. H.

doi:10.23919/empc.2017.8346881

Cited by 2 publications

(2 citation statements)

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“…This shrinkage can be partly attributed to the filling of the cracks in the reactive foil layer (For some applications, the necessity to fill the cracks sets a lower limit for the thickness of the solder layer: if thinner solder layers are used, the cracks can either not be filled, which may lead to problems if e.g., a hermetic joint is required, or the remaining solder layer becomes too thin, which may lead to problems in case of components with high surface roughness and waviness.). However, the here observed shrinkage can mainly be attributed to the pronounced lateral outflow of liquid Sn out of the joining zone during the bonding step, driven by the application of the uniaxial pressure (also see [23]). Note that this practical issue prevents modelling of the actual time-temperature-profiles as e.g., performed in [11]: the observed lateral outflow of liquid solder leads to an undefined heat loss which makes correct modelling of the heat flow and of the corresponding time-temperature-profile impossible.…”

Section: Resultsmentioning

confidence: 77%

“…This indicates that, during reactive joining, the Sn layers were likely not liquefied completely throughout the whole bonding area, thus preventing lateral outflow of liquid Sn under pressure. With a speed of the reaction front of approximately 8 m s −1 for the commercial Ni(V)-Al RFs used here (determined with a high-speed camera), the total reaction time from one side of the 4 mm × 4 mm bonding area to the other is only about 0.5 ms (also see [23]). Hence, in case of Cu, the solder layer was in the liquid state for less than 0.5 ms, which corresponds reasonably well to model predictions for a similar scenario [11].…”

Section: Resultsmentioning

confidence: 99%

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Joining with Reactive Nano-Multilayers: Influence of Thermal Properties of Components on Joint Microstructure and Mechanical Performance

et al. 2019

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Reactive nano-multilayers (RNMLs), which are able to undergo a self-heating exothermal reaction, can, e.g., be utilised as a local heat source for soldering or brazing. Upon joining with RNMLs, the heat produced by the exothermal reaction must be carefully adjusted to the joining system in order to provide sufficient heat for bond formation while avoiding damaging of the joining components by excessive heat. This heat balance strongly depends on the thermal properties of the joining components: a low thermal conductivity leads to heat concentration within the joining zone adjacent to the RNML, while a high thermal conductivity leads to fast heat dissipation into the components. The quality of the joint is thus co-determined by the thermal properties of the joining components. This work provides a systematic study on the influence of the thermal properties upon reactive joining for a set of substrate materials with thermal conductivities ranging from very low to very high. In particular, the evolution of the microstructure within the joining zone as a function of the specific time-temperature-profile for the given component material is investigated, focusing on the interaction between solder, RNML foil and surface metallisations, and the associated formation of intermetallic phases. Finally, the specific microstructure of the joints is related to their mechanical performance upon shear testing, and suggestions for optimum joint design are provided.

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Section: Resultsmentioning

confidence: 77%

Section: Resultsmentioning

confidence: 99%

Joining with Reactive Nano-Multilayers: Influence of Thermal Properties of Components on Joint Microstructure and Mechanical Performance

et al. 2019

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Reactive Joining of Thermally and Mechanically Sensitive Materials

Rheingans

Furrer

Neuenschwander

et al. 2018

Journal of Electronic Packaging

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Reactive joining, i.e., utilization of an exothermal reaction to locally generate the heat required for soldering or brazing, represents an emerging technology for flexible and benign joining of heat-sensitive materials, e.g., for microelectromechanical systems (MEMS) applications. However, for successful reactive joining, precise control of heat production and heat distribution is mandatory in order to avoid damaging of the components during the process. For the exemplary case of borosilicate glass, the reactive joining process for a both thermally and mechanically sensitive material is developed. Employing various nondestructive and destructive testing methods, typical problems which can occur upon reactive joining are identified, e.g., exposure of the joining zone to excessive temperatures, experience of thermal shock by the substrate due to sudden temperature increase, and generation of residual stresses in substrate and soldering zone. Utilizing the results of nondestructive and destructive testing, procedures for successful reactive joining of borosilicate glass, silicon and aluminum oxide are provided.

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Acceleration measurements during reactive bonding processes

Cited by 2 publications

References 1 publication

Joining with Reactive Nano-Multilayers: Influence of Thermal Properties of Components on Joint Microstructure and Mechanical Performance

Joining with Reactive Nano-Multilayers: Influence of Thermal Properties of Components on Joint Microstructure and Mechanical Performance

Reactive Joining of Thermally and Mechanically Sensitive Materials

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