A solution for modern high power circuit boards

Stefan Rohde, who is responsible for Wirelaid and high power products at Würth Elektronik, comments: "The partial thick copper technology has shown interesting results, when high current is required on some parts of the PCB and complex control electronics on the other parts. For the design of a printed circuit board, there are several important aspects to take into account. Among others, current and maximum temperatures play a key role."

First things first: Modern components require higher currents if they are to be incorporated into a circuit board. These currents generate higher temperature on the circuit board and in the surrounding environment – a critical aspect for heat sensitive components. In addition to this, devices are getting smaller, but are simultaneously taking on ever more comprehensive tasks. This means less space for more complex control electronics.

Modern circuit boards must therefore overcome all the different challenges: a compact PCB must safely carry high currents and as many fine pitch tracks as possible.

"When power and control electronics are combined on a board, large copper planes are no longer required as high current conductors. All that is required is that, where required, the boards are reinforced with copper wiring. With this technology, the designer can increase the copper cross section at certain points while maintaining a low layer count for the board. This reduces the volume and can simultaneously meet the current and heat dissipation requirements. To simplify, this technology saves some money because copper is expensive and less is used," explains Stefan Rohde.

Wirelaid production sounds quite simple: silver plated copper wires are fixed onto a copper foil using welding points and then pressed using standard production processes together with the printed circuit board substrate. Done.

The partial thick copper technology has been used for drive technology, engine electronics as well as AC and inverters.

The advantages of Wirelaid technology:

• Reduced system volume,
• Wires replacing the thick copper,
• Heat reduction due to smaller cross-sectional area of copper,
• Elimination of connectors,
• Reduced number of layers,
• Combination of power and signal processing electronics on one single PCB,
• Reduction of system cost,
• Improved heat dissipation,
• Better soldering process in comparison with traditional thick copper technology,
• Thinner copper layers,
• Fewer thick copper areas through the use of partial power management.

Würth Elektronik has created a Wirelaid design guide for customers which shows what spacing and dimensions should be used. The design guide also contains an overview of the current carrying capacity of the different wire sizes. "We are currently working with 1.4 mm and 0.8 mm thick copper wires that are embedded either on the outer or inner layers of the board. As with all complex designs, we offer our customers personal support in the development of the PCB," Rohde concludes.