University of Oulu

Acharya, S.; Chouhan, S.S.; Delsing, J. Fabrication Process for On-Board Geometries Using a Polymer Composite-Based Selective Metallization for Next-Generation Electronics Packaging. Processes 2021, 9, 1634.

Fabrication process for on-board geometries using a polymer composite-based selective metallization for next-generation electronics packaging

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Author: Acharya, Sarthak1,2; Chouhan, Shailesh Singh1; Delsing, Jerker1
Organizations: 1Embedded Internet System Laboratory, Department of Computer Science, Electrical & Space Engineering, Luleå University of Technology, 971 87 Luleå, Sweden
2Department of Information Technology & Electrical Engineering, University of Oulu, 90570 Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 6.2 MB)
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Language: English
Published: Multidisciplinary Digital Publishing Institute, 2021
Publish Date: 2021-10-12


Advancements in production techniques in PCB manufacturing industries are still required as compared to silicon-ICs fabrications. One of the concerned areas in PCBs fabrication is the use of conventional methodologies for metallization. Most of the manufacturers are still using the traditional Copper (Cu) laminates on the base substrate and patterning the structures using lithography processes. As a result, significant amounts of metallic parts are etched away during any mass production process, causing unnecessary disposables leading to pollution. In this work, a new approach for Cu metallization is demonstrated with considerable step-reducing pattern-transfer mechanism. In the fabrication steps, a seed layer of covalent bonded metallization (CBM) chemistry on top of a dielectric epoxy resin is polymerized using actinic radiation intensity of a 375 nm UV laser source. The proposed method is capable of patterning any desirable geometries using the above-mentioned surface modification followed by metallization. To metallize the patterns, a proprietary electroless bath has been used. The metallic layer grows only on the selective polymer-activated locations and thus is called selective metallization. The highlight of this production technique is its occurrence at a low temperature (20–45 °C). In this paper, FR-4 as a base substrate and polyurethane (PU) as epoxy resin were used to achieve various geometries, useful in electronics packaging. In addition, analysis of the process parameters and some challenges witnessed during the process development are also outlined. As a use case, a planar inductor is fabricated to demonstrate the application of the proposed technique.

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Series: Processes
ISSN: 2227-9717
ISSN-E: 2227-9717
ISSN-L: 2227-9717
Volume: 9
Issue: 9
DOI: 10.3390/pr9091634
Type of Publication: A1 Journal article – refereed
Field of Science: 215 Chemical engineering
Funding: The authors would like to acknowledge the European Project: Productive 4.0 and InterregNord-COMPACT for the financial support. The entire work has done in the Clean Room, EISLAB, in the Department of Computer Science, Electrical and Space Engineering, LUT. The authors are thankful to the Master thesis student Linus Karlquist for his support in fabrication of embedded inductor. The authors also thankful to Cuptronic Technology AB, Rosersberg, Sweden for providing the proprietary CBM chemistry and the Copper bath.
Copyright information: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (