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Technological change of printed circuit boards The increasing use of renewable energies and CO2-reduced drive technologies leads to new challenges in the power electronics sector. The resulting high currents and the required heat dissipation concepts can only be achieved by adjusted designs of the printed circuit boards. The highly dynamic development in the hardware sector is constantly subject to challenges in terms of economic efficiency. Therefore, the systems are analysed today with accompanying design-to-cost studies to find the best possible solutions. Decisive advantages are also provided by development projects, involving the customer and the supplier to ensure a successful launch of series production. Schweizer Electronic AG concentrates on special solutions for power electronics, embedding and system cost reduction and is now offering a comprehensive module system with numerous design options. Since different printed circuit technologies are more and more frequently combined due to limited installation space and cost advantages, the "inverter demonstrator" will present the existing possibilities in the sections below. Today, photovoltaic inverters contain between 3 and 22 assemblies. This number can be reduced to only one assembly by means of an intelligent design. This is how maximum efficiency can be combined with low system costs. The demonstrator is based on the principal concept of the „all in 1 PCB“, consisting of ready-made inserts with function-matched build ups. The reliable manufacturability is a result of the experiences gained with the Combi Board, Inlay Board and WirelaidTM (produced in combination with Jumatech). Optionally, active and passive components can be also embedded in the board. In the logic area, the i² Board® allows Bare Dies to be integrated on the interposer platform with other passive components. In the power area, the p² Pack® allows to substitute expensive DCBs (Direct Copper Bonding substrates: ceramic substrates) by embedding MOSFET or IGBT directly into the circuit structure. Finally, the FR4 Flex technology allows to adapt different functional areas to the equipment configuration by means of bending technology. Our outstanding equipment and process technology allows additional design freedom in the contacting area.

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The base material of the demonstrator is an inner layer with a thickness of 2 mm. This means that after the lamination process you get a usual 4 layer PCB.

The technologies in detail: Wirelaid technology: An alternative to thick copper technology is, among other technologies, the

patented wirelaid technology by Jumatech which has been used by Schweizer Electronic AG for

more than two years. In this technology, discreet wires are welded inside the printed circuit board.

This allows partial and exact enlarging of the cross section of the power path for managing high

currents. These Silverplated copper wires inside the board create therefore additional connections

for conducting high currents. The complex etching of the copper layer with a thickness of up to 400

µm in not required and the SMT-compliant outer layer remains free for signal wiring. Thus, it is

also possible to place the control electronics and the power electronics together on one board or

even on one layer. For this solution, cost consideration plays, among other aspects, a very

important role.

Wirelaid insert (capacitor area)

(2 x 35 µm Cu + wires 250 x 800 µm)

Combi board: »Combi Board« is designed by SCHWEIZER and its concept is similar to Wirelaid.

The basic idea is to apply thick copper only in necessary areas for the most effective use of the

expensive base material. Combi Board has an inner layer with both thick copper areas for

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high current applications and standard copper thickness for the finer signal routing. This design is

also suitable for combining logic and power electronic on one board.

Power supply unit of a Combi Board 4 x 210 µm Cu (e.g. also planar transformer)

HDI Combi Board: The main emphasis in this version is placed on economic aspects.

Considerable cost reductions can be obtained by use of complex inserts in the circuit structures

that are otherwise relatively simple. After printing, the „all in 1 PCB“ demonstrator with insert with 6

layers has a structure with 8 layers in which the basic circuit has only 4 layers.

HDI Combi Board 6 x 18 µm Cu (logic area)

Inlay Board: If maximum heat dissipation and maximum current carrying capacity are requested,

inlay board is the technology of choice, e. g. for replacing lead frames. On the circuit board an

area can be created that allows current peaks significantly higher than 1,000 A. For this, copper

inlays with a thickness of up to 2 mm must be used. Inlays are also recommended for pure heat

dissipation from the components.

Cu inlay with a thickness of 2 mm Board „inlay incorporation“ 4 x 35 µm Cu (MOSFET heat dissipation) (Bridge configuration)

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The demonstrator design

Optional power embedding with p² Pack®

for DMOS or IGBT

Optional logic embedding with i² Board®

for CMOS or BCDMOS

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List of the connection technologies used

The electrical connection of the inserts is established exclusively by means of the two outer layers (in the bending area on only one of the two layers)

Coated via plugging (via in pad)

Laservia (filling) 130µm

Mechanical deep drill holes 500µm / 400µm in depth pth Hole diameter > 7 mm 5 mil structures with 70 µm AL-Cu 2 Cu layers in the flex area Combi plating panel/plating with pattern

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Version May