Thick copper, Iceberg® and HSMtec® are three different technologies for high-current printed circuit boards. The article compares the three technologies and explains the design possibilities, current carrying capacity and heat dissipation of the power semiconductors.
The motor control system adjusts speed, power and torque to demand and operating conditions and plays a key role in the energy efficiency of industrial motors and vehicles. There are around 30 motors in one vehicle alone, e.g. for the blower, engine cooling, water and oil pump, power windows, front and rear window wipers.
On the hardware side, users and system manufacturers are demanding innovation in components for signal acquisition, signal conversion and signal conditioning. The manufacturers of printed circuit boards and connection technology have also adapted to this market: Manufacturing processes, materials and designs are optimized for the special requirements of current carrying capacity, thermal management and reliability.
From the point of view of the printed circuit board, the specifications of the drive electronics can be summarized in five points:
1. high integration density,
2. reliability of the electronic assembly,
3. rapid heat dissipation,
4. high currents combined with control electronics,
5. reduce system costs, e.g. by switching to SMD components, fewer components or assembly processes.
A smart solution is to combine the requirements for the power section and control electronics, load circuits and control on one PCB instead of two - large conductor cross-sections and large insulation distances for the high-current conductors and fine conductor structures for the control. This eliminates plug connections, cables and busbars, assembly steps and risks that limit reliability. This in turn saves space and increases reliability and cost-effectiveness.
The Optimal PCB design for power electronics and high-current applications determine five key aspects:
1. knowledge of the technical possibilities of the process, which specifies special design rules.
2. the dimensioning of the high-current conductors and insulation distances.
3. the selection, combination and maximum utilization of materials.
4. the layer structure, which is decisive for the current carrying capacity and heat dissipation.
5. a thermally optimized circuit board design.
The PCB specialist KSG offers three technologies that are used for these applications: Thick copper technology, Iceberg® and HSMtec® technology. The standard base material FR4 can be used in all three applications.
Thick copper PCBs distribute the power losses horizontally
The PCB industry generally speaks of thick copper when copper structures are greater than 105 µm. With up to four inner layers of 400 µm copper each, a current carrying capacity of several hundred amperes is possible. Ideally, the thick copper conductors are located in the inner layers.
The advantages of the thick copper PCB include flexibility when changing the layout, the compact design, simple processing/assembly and comparatively low modification costs as well as the standard processes of the PCB industry. Only relatively coarse structures can be produced due to the strong undercutting.
Important to know: FR4 laminates with a base copper cladding >105 µm are not inexpensive due to the high copper content. In comparison with a standard laminate with 18 µm lamination on both sides, the factor is around 1:8 to 1:10 in terms of material costs.21
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