All About Flex: Plated Through-holes in Flexible Circuits
October 29, 2015 | Dave Becker, All FlexEstimated reading time: 4 minutes
Electroless copper plating involves immersing the laminate in a series of baths that include a catalyst (usually palladium) followed by an alkaline, chelated solution of copper. Copper is thereby chemically bonded to all surfaces that are immersed. This chemically bonded coating is rather thin, but it allows electrical current to flow across the dielectric, which enables electroplating. Figure 2 depicts the through-hole immediately after electroless copper plating (technically it is not a plating process since electrical current is not used).
Figure 2: Electroless plating on the hole wall.
Figure 2 shows that a very thin layer of copper is deposited over the through-hole. Electroplating is next. Figure 3 depicts the through-hole after electroplating.
Figure 3: Electrolytic plating over electroless copper.
The through-hole now has a solid coating of copper that is both electrically and mechanically robust.
Shadow Plating
The Shadow® process performs the same basic function as the electroless plating process, which is to create a conductive bridge across the insulating layers so that electroplating can be performed.
The drilled copper laminate is immersed in a solution with conductive carbon particles. The carbon will adhere to the entire surface, creating a very thin, fragile layer. A micro-etch is then performed that removes the carbon from the copper material, so that only the dielectric areas remain coated, as shown in figure 4:
Page 2 of 4
Suggested Items
Designer’s Notebook: What Designers Need to Know About Manufacturing, Part 2
04/24/2024 | Vern Solberg -- Column: Designer's NotebookThe printed circuit board (PCB) is the primary base element for providing the interconnect platform for mounting and electrically joining electronic components. When assessing PCB design complexity, first consider the component area and board area ratio. If the surface area for the component interface is restricted, it may justify adopting multilayer or multilayer sequential buildup (SBU) PCB fabrication to enable a more efficient sub-surface circuit interconnect.
Insulectro’s 'Storekeepers' Extend Their Welcome to Technology Village at IPC APEX EXPO
04/03/2024 | InsulectroInsulectro, the largest distributor of materials for use in the manufacture of PCBs and printed electronics, welcomes attendees to its TECHNOLOGY VILLAGE during this year’s IPC APEX EXPO at the Anaheim Convention Center, April 9-11, 2024.
ENNOVI Introduces a New Flexible Circuit Production Process for Low Voltage Connectivity in EV Battery Cell Contacting Systems
04/03/2024 | PRNewswireENNOVI, a mobility electrification solutions partner, introduces a more advanced and sustainable way of producing flexible circuits for low voltage signals in electric vehicle (EV) battery cell contacting systems.
Heavy Copper PCBs: Bridging the Gap Between Design and Fabrication, Part 1
04/01/2024 | Yash Sutariya, Saturn Electronics ServicesThey call me Sparky. This is due to my talent for getting shocked by a variety of voltages and because I cannot seem to keep my hands out of power control cabinets. While I do not have the time to throw the knife switch to the off position, that doesn’t stop me from sticking screwdrivers into the fuse boxes. In all honesty, I’m lucky to be alive. Fortunately, I also have a talent for building high-voltage heavy copper circuit boards. Since this is where I spend most of my time, I can guide you through some potential design for manufacturability (DFM) hazards you may encounter with heavy copper design.
Trouble in Your Tank: Supporting IC Substrates and Advanced Packaging, Part 5
03/19/2024 | Michael Carano -- Column: Trouble in Your TankDirect metallization systems based on conductive graphite or carbon dispersion are quickly gaining acceptance worldwide. Indeed, the environmental and productivity gains one can achieve with these processes are outstanding. In today’s highly competitive and litigious environment, direct metallization reduces costs associated with compliance, waste treatment, and legal issues related to chemical exposure. What makes these processes leaders in the direct metallization space?