Documenting Your Flex Circuit Design
September 16, 2020 | Tony Plemel, Flexible Circuit TechnologiesEstimated reading time: 1 minute

As a flex circuit applications engineer, when I receive an RFQ, the first thing I do is look at the customer’s data and review their manufacturing notes. Quite often, I find notes that supersede IPC specifications in manufacturing documents, as customers often believe these added notes and associated specifications will make the circuit more robust. However, these non-standard IPC manufacturing specifications/notes can wreak havoc on the manufacturing process and can actually lead to a less robust circuit.
For example, a customer will sometimes specify additional copper plating, believing it will result in a more reliable circuit. In reality, that type of requirement can make the circuit less reliable, more difficult to manufacture, and more expensive. When manufacturing yields go down, the price goes up!
In taking a deeper dive into manufacturing notes and the potential issues that they can create, let’s use a three-layer multilayer flexible circuit as an example. The first note on a manufacturing print is usually “Manufacture to IPC6013, Class 2, Type 3.” This note should always be included; I cannot stress that enough!
Unfortunately, in the continued review of the documentation, I often find one or more additional conflicting notes further down in the manufacturing notes that overrule IPC6013 specifications.
Copper Plating
One example would be “Minimum copper plating shall be 0.0015”.” This note supersedes the IPC-6013 specification in Table 1.
Table 1: IPC-6013 copper plating requirements.
PCB designers who are not well-versed in flex circuit manufacturing may not know that exceeding IPC-6013 of 984 µin (0.000984”) can cause the circuit to be less reliable and possibly cause problems later in the manufacturing process. Having a specified requirement this large (0.000516” thicker) will require the plating line at the factory to plate more than 0.0015” to ensure the minimum plating is 0.0015” thick.
To read this entire article, which appeared in the September 2020 issue of Design007 Magazine, click here.
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.