In the HSMtec® process, 500 µm thick copper elements with variable widths from 2 to 12 mm and individual lengths are laid in the inner layers of the multilayer and embedded in the PCB. Through the partial integration of copper profiles into the PCB, high-current paths – or heat management and fine conductor layout – can be easily combined and adapted to the spatial conditions. Since the copper profiles are partially integrated into the PCB, load and logic or power and control electronics can be combined on one PCB.
The copper elements are bonded to the etched inner and/or outer layers using ultrasonic bonding technology. The integrated copper elements transmit currents of up to 400 A and also quickly reduce heat generation to permissible partial and system temperatures. This enables easy integration into a standard multilayer manufacturing process with subsequent pressing of the individual layers. A wide range of design variants allow high currents and heat losses from components to be fed specifically into PCBs – without any further external work steps.
The HSMtec® PCB technology combines load and logic on one assembly with minimal PCB area. This makes it possible to meet the electrical specifications for dielectric strength and insulation classes in automation as well as demanding temperature conditions with limited installation space in automotive electronics.
A look at the specific thermal conductivity shows the importance of the continuous metallic path from source to sink and the potential of HSMtec®. Copper conducts heat 1000 times better than FR4. The intelligent combination of integrated copper profiles with Thermovias makes it possible to connect the power components directly to the copper profiles and avoid bottlenecks in the thermal path.
A thermally optimised layer structure also ensures rapid heat spreading and supports the entire thermal concept. A practical example shows this clearly: The current-carrying capacity of a conductor track can double if there are two internal ground layers underneath that have no self-heating. Another example shows the potential of Thermovias: On an area of 10 mm x 10 mm it is possible to place more than 400 plated-through holes with a diameter of 0.25 mm, which means that the area then consists of 10% copper.
The effective thermal conductivity of such an FR4 surface increases to 30 W/m-K with this design measure. This makes this design a hundred times more thermally conductive than FR4 and even ten times more conductive than the best thermal conduction substrates. HSMtec® has been qualified by independent testing institutes and uses standard FR4 material. Moreover, it is manufactured in the standard production process and can be further processed in the usual assembly and soldering process.
The connection technology: highly current-optimised and compact
The PCB connection components from Weidmüller’s Omnimate Power range complement the HSMtec® PCB. Designed for servo controllers and frequency converters, the PCB terminals are available with pitches of up to 15 mm and a power range of up to 150 A/1000 V (IEC) and 127 A/600 V (UL) and different contact types. HSMtec® PCBs are also contacted with screw and pressure contacts especially for IGBTs, press-fit contacts in compliance with the necessary press-fit tolerances and with solder contacts for through-hole technology (THT) or with reflow-capable components for automated SMT processes.