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Surface Technology for Optical and Electrical Connectors
Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis treats surface engineering with the purpose of improved quality of optical and electricalconnectors with a focus on electroplated and magnetron sputtered materials. In electroforming of tools formanufacturing optical connectors, the influence of ultrasonic agitation on intrinsic stresses and fillingproperties of electroplated Ni has been studied. It is established that the ultrasonic agitation at the substratesurface during deposition impacts the intrinsic stresses making it possible to increase deposition rate viacurrent density, with stress-free or low-stress levels in the Ni layers. Reduced variations of the intrinsicstress over the surface with the current density is a further important result. Filling of grooves byelectroplating of Ni using ultrasonic agitation is demonstrated. This is due to increasing mass transport ofspecies into the grooves compared to conventional pumped agitation. The enhanced filling propertiesmakes it possible to electroplate Ni in the bottom of high-aspect-ratio grooves. In order to industriallyimplement new nanocomposite coatings on electronic connectors, studies have been performed regardingthe thermal diffusion barrier properties against Cu for Ti-Si-C and Ti-Si-C-Ag nanocomposites, depositeddirectly onto Cu substrates or with sputtered Ni, Ti or electroplated Ni as an intermediate coating. Theapplication of an electroplated Ni diffusion barrier coating, hinders Cu from reaching the surface of thenanocomposites. Also, Ti-Si-C-Ag nanocomposite deposited on magnetron sputtered Ni or Ti on Cusubstrates hinder Cu from diffusing to the surface after annealing. The contact resistance of Ag-Pdtopcoated Ti-Si-C-Ag-Pd and Ti-Si-C-Ag nanocomposite coatings in contact with hard gold is shown tocompete with hard gold in contact with itself, as electrical contact coatings at contact forces around 5 N.Ag-Pd topcoated Ti-Si-C-Ag-Pd in contact with hard gold is shown to have approximately the same contactresistance as hard gold in contact with hard gold at contact forces around 0.1 N, which here is in the 10 mΩrange, while Ti-Si-C-Ag nanocomposite coatings in contact with hard gold has a contact resistance that isup to 10 times higher. The overall contribution of this thesis can be summarised as a deeper knowledge andunderstanding of techniques and coatings, that help reduce cost and increase reliability of electronics.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press , 2010. , 73 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1342
National Category
Natural Sciences
Identifiers
URN: urn:nbn:se:liu:diva-63626ISBN: 978-91-7393-299-8 (print)OAI: oai:DiVA.org:liu-63626DiVA: diva2:381748
Public defence
2010-11-26, Planck, Fysikhuset, Campus Valla, Linköpings universitet, Linköping, 10:15 (Swedish)
Opponent
Supervisors
Available from: 2010-12-28 Created: 2010-12-28 Last updated: 2016-08-31Bibliographically approved
List of papers
1. Electrochemically based low-cost high precision processing in MOEMS packaging
Open this publication in new window or tab >>Electrochemically based low-cost high precision processing in MOEMS packaging
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2009 (English)In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 0019-4686, Vol. 54, no 9, 2458-2465 p.Article in journal (Refereed) Published
Abstract [en]

Precision processing in MOEMS (micro-opto-electromechanical systems) packaging has been studied based on electrochemical processes with the purpose of establishing technology for low-cost multifunctional encapsulation of microsystems and assembly of opto-electric access links in polymer.

The electrochemically based processes studied in this paper include:

1. Electroforming of a polymer moulding tool (stamper) in a nickel sulphamate electrolyte on a highprecision 3D etched silicon template.

2. Patterning of 3D surfaces by an electrophoretic photoresist.

3. Precision plating of Au and Sn for self-alignment of chips by eutectic Au-Sn solder.

The results show that nickel stampers with adequately low internal stress can be electroformed on 3D silicon wafers. Furthermore, 3D polymer samples manufactured by the nickel stampers can be patterned with metal lines down to 20 mu m width using electrophoretic photoresist. Finally, eutectic Au-Sn solder bumps are realized by electroplating of Au and Sn followed by reflowing, satisfying the demands on dimension and alloy composition control over a 4 in. Si wafer.

Keyword
Electroforming, Micro-replication, 3D patterning, Self-aligning soldering, MOEMS packaging
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-17751 (URN)10.1016/j.electacta.2008.03.084 (DOI)
Available from: 2009-04-18 Created: 2009-04-17 Last updated: 2016-08-31Bibliographically approved
2. Electroplating of nickel in grooves under the influence of low and medium frequency ultrasound
Open this publication in new window or tab >>Electroplating of nickel in grooves under the influence of low and medium frequency ultrasound
2011 (English)In: Journal for Electrochemistry and Plating Technology, ISSN 1866-7406, Vol. 1, no 3, 19-28 p.Article in journal (Refereed) Published
Abstract [en]

The effect of ultrasonics on filling properties has been studied by Ni electroplating from a sulphamate electrolyte in high aspect ratio grooves. The experiments have been performed with two different modes of ultrasound: a) 25 kHz ultrasound with an effect of 225 W directed perpendicular to the substrate surface; b) ultrasonic standing waves of 100 kHz and 400 kHz parallel to the substrate surface. It was found that both methods improve the filling in grooves that are between 0.35 and 1 mm wide with aspect ratios between 0.6 and 3, compared to electroplating with conventional agitation. Under the investigated conditions the 400 kHz standing wave parallel to the surface was most efficient to improve filling of grooves.

Keyword
Filling; Electrodeposition; Ultrasound; Nickel; Electroforming
National Category
Metallurgy and Metallic Materials Other Materials Engineering Manufacturing, Surface and Joining Technology
Identifiers
urn:nbn:se:liu:diva-63621 (URN)10.12850/ISSN2196-0267.JEPT643 (DOI)
Available from: 2010-12-28 Created: 2010-12-28 Last updated: 2016-08-31Bibliographically approved
3. Influence of ultrasound and cathode rotation on the formation of intrinsic stress in Ni films during electrodeposition
Open this publication in new window or tab >>Influence of ultrasound and cathode rotation on the formation of intrinsic stress in Ni films during electrodeposition
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2011 (English)In: Transactions of the Institute of Metal Finishing, ISSN 0020-2967, E-ISSN 1745-9192, Vol. 89, no 3, 137-142 p.Article in journal (Refereed) Published
Abstract [en]

The influence of 25 kHz ultrasound and cathode rotation during electroplating of Ni films on Si wafers has been studied with respect to intrinsic stress formation. Current densities from 1.6 A dm-2 up to 28.3 A dm-2 were used in an additive-free Ni sulphamate electrolyte. In general more efficient agitation by either ultrasound or cathode rotation was found to reduce intrinsic stress towards compressive levels compared to conventional agitation with an electrolyte circulation pump. Further more, intrinsic stresses become less dependent on changes in current density. The latter effect is most pronounced for ultrasonic agitation. Structure analysis of samples deposited by ultrasonic agitation show dense deposits with initially smaller grains at high ultrasonic effect. Locally increased temperature at the substrates surface could be an important effect of ultrasound agitation.

Place, publisher, year, edition, pages
Institute of Metal Finishing, 2011
Keyword
Intrinsic stress; Electrodeposition; Ultrasound; Nickel; Electroforming
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-63622 (URN)10.1179/002029611X13014892461794 (DOI)000291382200005 ()
Available from: 2010-12-28 Created: 2010-12-28 Last updated: 2017-12-11Bibliographically approved
4. Ni and Ti diffusion barrier layers between Ti-Si-C-Ag nanocomposite coatings and Cu-based substrates
Open this publication in new window or tab >>Ni and Ti diffusion barrier layers between Ti-Si-C-Ag nanocomposite coatings and Cu-based substrates
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2012 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 206, no 8-9, 2558-2565 p.Article in journal (Refereed) Published
Abstract [en]

Sputtered Ni and Ti layers were investigated as substitutes for electroplated Ni as adiffusion barrier between Ti-Si-C and Ti-Si-C-Ag nanocomposite coatings and Cu orCuSn substrates. Samples were subjected to thermal annealing studies by exposure to400 ºC during 11 h. Dense diffusion barrier and coating hindered Cu from diffusing tothe surface. This condition was achieved for electroplated Ni in combination withmagnetron-sputtered Ti-Si-C and Ti-Si-C-Ag layers deposited at 230 ºC and 300 ºC,and sputtered Ti or Ni layers in combination with Ti-Si-C-Ag deposited at 300 ºC.

Place, publisher, year, edition, pages
Elsevier, 2012
Keyword
Titanium carbide; nanocomposite; physical vapor deposition (PVD); diffusion; barrier; annealing
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-63624 (URN)10.1016/j.surfcoat.2011.11.014 (DOI)000300458500069 ()
Note

funding agencies|The European EraSME Program||Swedish Knowledge Foundation||The Swedish Board for Innovation Systems VINN Excellence Center on Functional Nanostructured Materials (FunMat)||

Available from: 2010-12-28 Created: 2010-12-28 Last updated: 2017-12-11Bibliographically approved
5. Contact resistance of Ti-Si-C-Ag and Ti-Si-C-Ag-Pd nanocomposite coatings
Open this publication in new window or tab >>Contact resistance of Ti-Si-C-Ag and Ti-Si-C-Ag-Pd nanocomposite coatings
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2012 (English)In: Journal of Electronic Materials, ISSN 0361-5235, E-ISSN 1543-186X, Vol. 41, no 3, 560-567 p.Article in journal (Refereed) Published
Abstract [en]

Ti-Si-C-Ag-Pd and Ti-Si-C-Ag nanocomposite coatings were deposited by magnetronsputtering on Cu substrates with an electroplated Ni layer. Analytical electronmicroscopy and x-ray diffraction show that the nanocomposites consist of TiC,Ag:Pd, and amorphous SiC. The contact resistance of these coatings against aspherical Au-Co surface was measured for applied contact force up 0 to 5 N. Ti-Si-CAg-Pd coatings with a Ag:Pd strike coating has ~10 times lower contact resistance atcontact forces below 1 N (~10 mΩ at ~0.1N), and ~2 times lower for contact forcesaround 5 N (<1 mΩ at 5 N), compared to the Ti-Si-C-Ag coating.

Place, publisher, year, edition, pages
Springer, 2012
Keyword
titanium carbide; nanocomposite; physical vapor deposition (PVD); contact resistance; surface roughness; silver palladium
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-63625 (URN)10.1007/s11664-011-1813-8 (DOI)000299930100022 ()
Note
Funding Agencies|European EraSME||Swedish Knowledge Foundation||Swedish Board for Innovation Systems VINN Excellence Center on Functional Nanostructured Materials (FunMat)||Available from: 2010-12-28 Created: 2010-12-28 Last updated: 2017-12-11Bibliographically approved

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