Fabrication Process for On-Board Geometries Using a Polymer Composite-Based Selective Metallization for Next-Generation Electronics Packaging

Abstract

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.

Artificial Intelligence-Based Portable Bioelectronics Platform for SARS-CoV-2 Diagnosis with Multi-nucleotide Probe Assay for Clinical Decisions

“…The proposed biochips were fabricated from commercially available inexpensive single-sided copper clads, via lithographic pattern transfer and sacrificial etching of unwanted metal (lithography setup supplied by Suss Micro Tec SE, Germany). , Each biochip (1.2 cm × 4 cm) contained three interdigitated sensors, with four contact pads (three for assessing the individual sensors with one common ground). Understandably, a more generalized design would include “ n ” interdigitated sensors, with “ n +1” contact pads.…”

Detailed Characterization of a Fully Additive Covalent Bonded PCB Manufacturing Process (SBU-CBM Method)

“…Electroless Cu bath (PEC-660 series) was purchased from J-KEM International, Stockholm, Sweden [28]. This method has been demonstrated for creating geometries with selective metallization [13]. The focus of this study is to examine the surface modification phenomena during each step of the SBU-CBM process to obtain the final Cu metallization.…”

“…The usage of polymeric materials and hybrid (ceramic) substrates in the electronics manufacturing industry has increased in recent years [7,10]. The fabrication process, presented in this paper, comes under non-contact PE technology which uses the LDW technique to make Cu interconnects with polymer-composite-based surface modification [11][12][13].…”

“…Concerning the fabrication gaps related to PCBs, those of ICs, a fully additive approach for PCBs has been demonstrated in previous literature [11,13,26]. The objectives of developing such a manufacturing process are to avoid adding extra steps to the process, achieve feature sizes comparable to the ICs, and replace the solder joints with printed electronic metallic interconnects.…”

“…So far, a minimum of 2.5 µm feature sizes has been achieved [11]. The replacement of bulky capacitors and inductors with embedded passives was demonstrated using this fabrication technique [13,26]. However, the steps involved in this production recipe have not been shown yet.…”