March: Heavy Copper technology

What's the difference between a Heavy Copper PCB and a Standard PCB?

Generally Heavy Copper PCBs are manufactured with the same processes than standard PCBs. Inner layer thicknesses might vary between 105 µm und 400 µm. Etch trenches will be deeper and wider for Heavy Copper Boards compared to standard PCBs. Filling up those trenches requires sufficient enough prepreg material in order to generate the required amount of resin during the lamination process.

Thermosimulation of a Heavy Copper PCB

Thermosimulation of a Heavy Copper PCB featuring 2 x 400 µm copper on inner layers and 2 x 105 µm on outer layers. Power dissipation of MOSFFETs: 10 W each.

How much current can be conducted by a Heavy Copper Board?

Depending on the used active and passive components, the cooling concept of the application and environmental conditions like e.g. ambient temperatures solutions for continuous currents of up to 250 A are well-established.

Can laser vias be reliably connected to heavy copper layers?

For conventional Heavy Copper PCBs laser vias can't be utilised since thick isolation layers lead to forbidden aspect ratios for the given laser hole diameter. For Heavy Copper PCBs mechanical depth drilling should be utilised.

How many Heavy Copper layers can be realized in a lay-up?

The layer count is limited by the maximum PCB thickness of 3.2 mm and the weight limit for working panels. Accordingly lay-ups with copper thicknesses of 4 x 400 µm, 6 x 210 µm or 10 x 105 µm of copper on inner layers are possible.

How can I contact a Heavy Copper board with a high-current connector?

High-Current press-fit contacts are suitable for the conduction of high currents into and out of Heavy Copper lay-ups. They are available in different power classes and various connector geometries. Direct soldering or screw-mounting processes are not recommended in order to avoid reliability constraints.

Why are classical heavy copper boards insufficient for some types of applications?

If applications require currents of a couple of 100 Amps whilst at the same time they have to dissipate high power losses classical Heavy Copper PCBs are reaching their physical limits. Therefore SCHWEIZER is currently developing the Heavy Copper T² technology (T² = thinner & thermally enhanced). The target is a reduction of the thermal resistance of the PCB compared to classical heavy copper lay-ups by up to 50 %.