-
-
News
News Highlights
- Books
Featured Books
- pcb007 Magazine
Latest Issues
Current IssueThe Hole Truth: Via Integrity in an HDI World
From the drilled hole to registration across multiple sequential lamination cycles, to the quality of your copper plating, via reliability in an HDI world is becoming an ever-greater challenge. This month we look at “The Hole Truth,” from creating the “perfect” via to how you can assure via quality and reliability, the first time, every time.
In Pursuit of Perfection: Defect Reduction
For bare PCB board fabrication, defect reduction is a critical aspect of a company's bottom line profitability. In this issue, we examine how imaging, etching, and plating processes can provide information and insight into reducing defects and increasing yields.
Voices of the Industry
We take the pulse of the PCB industry by sharing insights from leading fabricators and suppliers in this month's issue. We've gathered their thoughts on the new U.S. administration, spending, the war in Ukraine, and their most pressing needs. It’s an eye-opening and enlightening look behind the curtain.
- Articles
- Columns
- Links
- Media kit
||| MENU - pcb007 Magazine
Coated Ultra-Thin Copper on Printed Circuit Laminates
July 16, 2015 | Intrinsiq Materials Inc.Estimated reading time: 5 minutes

Nano copper-based electronic ink and associated processing have been developed to create ultra-thin copper on flexible PCB substrates. Using a unique nanomanufacturing process, nanomaterial is created, dispersed, and sintered, resulting in copper foil of one micron or less. The process is rapid and sufficiently low-temperature to allow deposition onto temperature-sensitive substrates such as polyimide, plastic and paper. The resulting foil can be etched and processed as well as electroplated or electrolessly plated without the use of palladium.
Applying thinner copper coatings to flexible PCB substrates than are currently available will allow for much finer etch resolution and increased circuit density. The roll-to-roll lamination process in use today limits the copper foil thickness due to manufacturing and handing ultra-thin copper. A coating process eliminates these problems.
Background
High-volume roll-to-roll flexible circuit manufacturers use plasma vapor deposition (PVD) to deposit a 0.5 micron copper thin film onto unclad flexible laminates. This process provides several advantages over using copper clad laminates. One such advantage is the ability to metalize pre-drilled holes simultaneously with the surface providing good adhesion, ease of handling, and very fine feature definition. However, this is a very expensive method for applying copper and requires very specialized equipment when using today’s industry standard processes.
Nanomanufacturing
Nanomanufacturing incorporates the plasma generation process to tightly control particle size and distribution and create very pure copper. Furthermore, the manufacturing process allows the copper particles to be encapsulated with a coating, thus preventing oxidation and agglomeration. For the purpose of coating printed circuit laminates, nanomaterial particles of around 90 nm are the optimal size. Smaller particle size distributions can affect the metal loading and larger (too large) will require excessive energy to sinter. The nanoparticles can then be dispersed into solvent based inks that can be used to create very thin and uniform coatings. The ink dispersions have long shelf and pot life without special handling or storage.
Nanocoating
The deposition equipment used to create ultra-thin copper coatings includes coaters, inkjet printers, and screen printers that are commercially available and typically used in the electronics industry today. The deposition is accomplished in open air without special environmental constraints because the coating on the nanoparticles prevents oxidation. This nano technology is being used to create copper coatings onto various substrates that, in the past, could only be accomplished by processes such as PVD.
The data presented herein was derived from nanomaterial that was slot die coated on a commercial system and air-impingent dried. It has been determined that care must be taken to thoroughly dry the material once applied to the laminate to remove all residual solvent. Failure to properly dry material can result in poor adhesion after sintering and failures in post-processing. This process has been successfully demonstrated on commercially available coating and sintering equipment. It is expected that spray, dip, and other coating processes will all show similar favorable results and allow custom tailoring of coating systems to meet specific needs.
Sintering
Once deposited, the applied material is sintered either photonically or in an oven using a reduction environment. In the case of photonic sintering, a millisecond flash from a Xenon or broadband source transforms the coated material from insulting to conductive. Once sintered, the material adheres to the substrate and can be processed. For the data and images presented in this article, the coated roll of 60 feet of Kapton was then sintered using a roll-to-roll Xenon pulsed-light sintering system (Xenon Corporation S-5000).
Commercially available film coating systems would need to be retrofitted with a production quality broad band flash system or an oven system with a reducing environment to sinter the nano into pure copper. This equipment is commercially available as well. Roll-to-roll application of the nano copper can replace the previously mentioned PVD method in the manufacturing of flexible circuit materials with much thinner copper foil than is currently available.
Testing Results
Preliminary testing has been conducted by Intrinsiq to assess the quality of the ultra-thin film material and the ability to use these ultra-thin film laminates in standard PCB production processing, including pre-cleaning, imaging, etching and plating. The steps in creating the material and the steps taken in the PCB fabrication process are outlined below.
Standard polyimide flexible circuit material (0.005” thick) was coated with a one-micron dried thickness of nano copper ink in a roll-to-roll process using commercial slot die coating from the photographic film industry. The dried coating was then sintered into a 0.5-micron copper film using a production broad band flash unit designed to be integrated inline for true roll-to-roll processing. The conductivity of the resultant ultra-thin film copper was measured with a four-point probe at pre-set intervals to monitor the level of sintering during the flash process. The bulk resistivity of the sintered thin-film copper material is on the order of 10X that of bulk copper and achieved a 5B adhesion. The thin-film copper will electroplate readily due to the very low resistance of the coating as described herein. Shown in Figure 1 are examples of electrolessly plated coated copper.
Several 6” x 12” pieces (panels) were cut from the produced roll of polyimide with the ultra-thin film of copper and processed at a local PCB fabricator. The materials were pre-cleaned with standard chemistry and then laminated with photo-resist. The panels were imaged with several IPC Peel Test Coupons, tape test coupons, and standard PCB circuit patterns.Page 1 of 2
Suggested Items
The Evolution of Picosecond Laser Drilling
06/19/2025 | Marcy LaRont, PCB007 MagazineIs it hard to imagine a single laser pulse reduced not only from nanoseconds to picoseconds in its pulse duration, but even to femtoseconds? Well, buckle up because it seems we are there. In this interview, Dr. Stefan Rung, technical director of laser machines at Schmoll Maschinen GmbH, traces the technology trajectory of the laser drill from the CO2 laser to cutting-edge picosecond and hybrid laser drilling systems, highlighting the benefits and limitations of each method, and demonstrating how laser innovations are shaping the future of PCB fabrication.
Day 2: More Cutting-edge Insights at the EIPC Summer Conference
06/18/2025 | Pete Starkey, I-Connect007The European Institute for the PCB Community (EIPC) summer conference took place this year in Edinburgh, Scotland, June 3-4. This is the third of three articles on the conference. The other two cover Day 1’s sessions and the opening keynote speech. Below is a recap of the second day’s sessions.
Day 1: Cutting Edge Insights at the EIPC Summer Conference
06/17/2025 | Pete Starkey, I-Connect007The European Institute for the PCB Community (EIPC) Summer Conference took place this year in Edinburgh, Scotland, June 3-4. This is the second of three articles on the conference. The other two cover the keynote speeches and Day 2 of the technical conference. Below is a recap of the first day’s sessions.
Preventing Surface Prep Defects and Ensuring Reliability
06/10/2025 | Marcy LaRont, PCB007 MagazineIn printed circuit board (PCB) fabrication, surface preparation is a critical process that ensures strong adhesion, reliable plating, and long-term product performance. Without proper surface treatment, manufacturers may encounter defects such as delamination, poor solder mask adhesion, and plating failures. This article examines key surface preparation techniques, common defects resulting from improper processes, and real-world case studies that illustrate best practices.
RF PCB Design Tips and Tricks
05/08/2025 | Cherie Litson, EPTAC MIT CID/CID+There are many great books, videos, and information online about designing PCBs for RF circuits. A few of my favorite RF sources are Hans Rosenberg, Stephen Chavez, and Rick Hartley, but there are many more. These PCB design engineers have a very good perspective on what it takes to take an RF design from schematic concept to PCB layout.