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Research Papers

Reactive Joining of Thermally and Mechanically Sensitive Materials

[+] Author and Article Information
Bastian Rheingans

Empa, Swiss Federal Laboratories for Materials
Science and Technology,
Überlandstrasse 129,
Dübendorf 8600, Switzerland
e-mail: bastian.rheingans@empa.ch

Roman Furrer

Empa, Swiss Federal Laboratories for Materials
Science and Technology,
Überlandstrasse 129,
Dübendorf 8600, Switzerland
e-mail: roman.furrer@empa.ch

Jürg Neuenschwander

Empa, Swiss Federal Laboratories for Materials
Science and Technology,
Überlandstrasse 129,
Dübendorf 8600, Switzerland
e-mail: juerg.neuenschwander@empa.ch

Irina Spies

Hahn-Schickard,
Wilhelm-Schickard-Strasse 10,
Villingen-Schwenningen 78052, Germany
e-mail: irina.spies@hahn-schickard.de

Axel Schumacher

Hahn-Schickard, Wilhelm-Schickard-Strasse 10,
Villingen-Schwenningen 78052, Germany
e-mail: axel.schumacher@hahn-schickard.de

Stephan Knappmann

Hahn-Schickard,
Wilhelm-Schickard-Strasse 10,
Villingen-Schwenningen 78052, Germany
e-mail: stephan.knappmann@hahn-schickard.de

Lars P. H. Jeurgens

Empa, Swiss Federal Laboratories for Materials
Science and Technology,
Überlandstrasse 129,
Dübendorf 8600, Switzerland
e-mail: lars.jeurgens@empa.ch

Jolanta Janczak-Rusch

Empa, Swiss Federal Laboratories for Materials
Science and Technology,
Überlandstrasse 129,
Dübendorf 8600, Switzerland
e-mail: jolanta.janczak@empa.ch

Contributed by the Electronic and Photonic Packaging Division of ASME for publication in the JOURNAL OF ELECTRONIC PACKAGING. Manuscript received February 28, 2018; final manuscript received July 20, 2018; published online September 10, 2018. Assoc. Editor: Xiaobing Luo.

J. Electron. Packag 140(4), 041006 (Sep 10, 2018) (8 pages) Paper No: EP-18-1016; doi: 10.1115/1.4040978 History: Received February 28, 2018; Revised July 20, 2018

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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References

The ITRS committee, 2015, “ The International Technology Roadmap for Semiconductors 2.0,” The ITRS committee, accessed Aug. 3, 2018, http://www.itrs2.net/
Adams, D. P. , 2015, “ Reactive Multilayers Fabricated by Vapor Deposition: A Critical Review,” Thin Solid Films, 576, pp. 98–128. [CrossRef]
Wang, J. , Besnoin, E. , Duckham, A. , Spey, S. J. , Reiss, M. E. , Knio, O. M. , and Weihs, T. P. , 2004, “ Joining of Stainless-Steel Specimens With Nanostructured Al/Ni Foils,” J. Appl. Phys., 95(1), pp. 248–256. [CrossRef]
Duckham, A. , Spey, S. J. , Wang, J. , Reiss, M. E. , Weihs, T. P. , Besnoin, E. , and Knio, O. M. , 2004, “ Reactive Nanostructured Foil Used as a Heat Source for Joining Titanium,” J. Appl. Phys., 96(4), pp. 2336–2342. [CrossRef]
Qiu, X. , and Wang, J. , 2008, “ Bonding Silicon Wafers With Reactive Multilayer Foils,” Sens. Actuators A, 141(2), pp. 476–481. [CrossRef]
Braeuer, J. , Besser, J. , Tomoscheit, E. , Klimm, D. , Anbumani, S. , Wiemer, M. , and Gessner, T. , 2013, “ Investigation of Different Nano Scale Energetic Material Systems for Reactive Wafer Bonding,” ECS Trans, 50(7), pp. 241–251. http://ecst.ecsdl.org/content/50/7/241.abstract
Wang, J. , Besnoin, E. , Knio, O. M. , and Weihs, T. P. , 2005, “ Effects of Physical Properties of Components on Reactive Nanolayer Joining,” J. Appl. Phys., 97(11), p. 114307. [CrossRef]
Masser, R. , Braeuer, J. , and Gessner, T. , 2014, “ Modelling the Reaction Behavior in Reactive Multilayer Systems on Substrates Used for Wafer Bonding,” J. Appl. Phys., 115(24), p. 244311. [CrossRef]
Hooper, R. J. , Davis, C. G. , Johns, P. M. , Adams, D. P. , Hirschfeld, D. , Nino, J. C. , and Manuel, M. V. , 2015, “ Prediction and Characterization of Heat-Affected Zone Formation in Tin-Bismuth Alloys Due to Nickel-Aluminum Multilayer Foil Reaction,” J. Appl. Phys., 117(24), p. 245104. [CrossRef]
Longtin, R. , Hack, E. , Neuenschwander, J. , and Janczak-Rusch, J. , 2011, “ Benign Joining of Ultrafine Grained Aerospace Aluminum Alloys Using Nanotechnology,” Adv. Mater, 23(48), pp. 5812–5816. [CrossRef] [PubMed]
Namazu, T. , Takemoto, H. , Fujita, H. , Nagai, Y. , and Inoue, S. , 2006, “ Self-Propagating Explosive Reactions in Nanostructured Al/Ni Multilayer Films as a Localized Heat Process Technique for Mems,” 19th IEEE International Conference on Micro Electro Mechanical Systems (MEMS), Istanbul, Turkey, Jan. 22–26, pp. 286–289.
Schumacher, A. , 2015, “ Montage Von Mikrosystemen Mit Reaktivem Nanofügen in Einer Fertigungsprozesskette (ReMTeC), Abschlussbericht,” Hahn-Schickard Gesellschaft, Villingen-Schwenningen, Germany, Technical Report.
Ho, C. E. , Tsai, R. Y. , Lin, Y. L. , and Kao, C. R. , 2002, “ Effect of Cu Concentration on the Reactions Between Sn-Ag-Cu Solders and Ni,” J. Electron. Mater, 31(6), pp. 584–590. [CrossRef]
Spies, I. , Schumacher, A. , Knappmann, S. , Rheingans, B. , Janczak-Rusch, J. , and Jeurgens, L. P. H. , 2017, “ Acceleration Measurements During Reactive Bonding Processes,” 21st European Microelectronics and Packaging Conference (EMPC) & Exhibition, Warsaw, Poland, Sept. 10–13, pp. 1–6.
SCHOTT Technical Glass Solutions GmbH, 2014, “ BOROFLOAT® 33—Thermal Properties, Mechanical Properties,” SCHOTT Technical Glass Solutions GmbH, Jena, Germany, accessed Aug. 3, 2018, www.schott.com
Deshpande, V. T. , and Sirdeshmukh, D. B. , 1961, “ Thermal Expansion of Tetragonal Tin,” Acta Crystallogr., 14(4), pp. 355–356. [CrossRef]
Wang, Y. , Liu, Z. K. , and Chen, L. Q. , 2004, “ Thermodynamic Properties of Al, Ni, NiAl, and Ni3Al From First-Principles Calculations,” Acta Mater., 52(9), pp. 2665–2671. [CrossRef]

Figures

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Fig. 1

Schematic representation of the joining setup: (a) front view and (b) top view; 1—upper substrate (4 mm × 4 mm), 2—surface metallization, 3—upper solder foil, 4—RF, 5—lower solder foil, 6—surface metallization, 7—lower substrate (10 mm × 20 mm), 8—ignition points

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Fig. 2

Results of different analysis methods for a reactively joined borosilicate glass specimen using 10 µm Sn foils (upper substrate, 4 mm × 4 mm; the red/light gray (print version) lines mark the approximate specimen boundaries): (a) optical bright-field image: Severe cracking of the glass and grayish/dark gray (print version) structures (cf. Fig. 3) can be observed; the weak rectangular patterns in the image originate from its compilation from smaller images. (b) optical image under DIC conditions: Additional color/contrast (print version) variations arise indicating that the glass substrate experiences an inhomogeneous state of stress. (c) C-scan amplitude map at short echo run-times from within the upper substrate: The cracks in the substrate are faintly visible. (d) Corresponding CT scan slice: Here, the cracks within the glass are not detected. (e) C-scan amplitude map at a run-time corresponding to the back echo of the substrate plate: Pores within the solder layer, leading to high amplitude values, can be clearly detected. The red/light gray (print version) contours indicate a threshold intensity level of ≥ 0.3 for pore definition, corresponding to a total pore fraction of about 35 % per area. (f) Corresponding CT-scan image for the upper solder layer showing pores in the solder layer as well as cracks within the RF. (g) CT scan slice through the RF layer, again showing the cracks within the RF. The contrast variations of the cracks are caused by their partial filling with solder material (then appearing brightly under the present contrast conditions).

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Fig. 3

OM image under DIC conditions at higher magnification. Apart from cracks, fine meandering structures with metallic gray/light gray (print version) appearance are visible at the interface.

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Fig. 4

Cross sections of a joint between borosilicate glass obtained by reactive soldering with a 60 µm Ni–Al RF and (a) 10 µm Sn solder foils and (b) 75 µm Sn solder foils. In both cases, the final thickness of the filler layers is strongly reduced by lateral outflow of solder. For the thinner solder foils in (a), a large amount of pores exists within the thin solder layers (the dark patches in (b) in the lower solder layer are artefacts introduced upon preparation).

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Fig. 5

SEM-EDX elemental mapping for a solder joint obtained for reactive soldering with 10 µm Sn foils (voltage: 20 kV, working distance: 7.7 mm). The (secondary electron) SEM image shows the layered structure of upper borosilicate glass substrate, metallization layer, solder layer and RF layer. The Ni-metallization of originally 500 nm thickness is completely dissolved and only the 100 nm thin Ti/W-coupling layer remains, appearing as a bright rim between glass and solder layer in the SEM image (this leads to the appearance of the meandering structures visible by OM, Fig. 3). The elements Ag, Cu, and In, originating from the InCuSil®-15 protective layer of the RF, are completely redistributed throughout the Sn solder layer. Cu and Ag form various different (separate) intermetallic phases with Sn, indicated by the complementary distribution of Sn and Cu, respectively Ag. Close to the former Ni-metallization layer, some ternary Ni–Cu–Sn intermetallic particles can be detected. In appears to be more or less homogeneously distributed.

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Fig. 6

Results of different analysis methods for a reactively joined borosilicate glass specimen (upper substrate) using 75 µm Sn foils and a reduced joining pressure: (a) OM-DIC image: Compared to the specimen joined with an insufficient amount of solder (Fig. 2(a)), no cracks and no grayish/light gray (print version) structures are visible. Color/contrast (print version) variations still arise indicating that also in this case the glass experiences an inhomogeneous state of stress. (b) C-scan amplitude map at a run-time corresponding to the back echo of the substrate plate: Pores within the solder layer are still visible, but exhibit a more compact appearance. Again, introducing an intensity threshold of ≥ 0.3 for pore definition (red/light gray (print version) contours), a pore fraction of about 18 % is obtained. (c) CT scan slice through the RF layer showing the pores in the solder layer and the cracks in the underlying RF layer.

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Fig. 7

SEM-EDX elemental mapping for a solder joint obtained for reactive soldering with 75 µm thick Sn foils (voltage: 20 kV, working distance: 10.5 mm; note the difference in scaling compared to Fig. 5). In contrast to the solder joint obtained with 10 µm thick Sn foils, the Ni-metallization is still intact. The elements Ag, Cu and In, which originate from the InCuSil®-15 protective layer of the RF, are again completely redistributed throughout the Sn solder layer, but the corresponding intermetallic particles formed by Cu and Ag are much sparser in relation to the total thickness of the solder layer.

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