Iceberg® circuit boards are partial thick copper circuit boards with mixed copper thicknesses of 105 and 400 µm on the same level in the outer layers. In the process, about two thirds of the thick copper is sunk into the base material. The “sinking” of the thick copper structures in the base material enables a uniform surface topography despite different copper thicknesses on the same layer. This allows the conductor flanks to be covered with solder resist in just one casting process.
Due to its planar surface, which simplifies assembly, the Iceberg® principle is recommended for thick copper PCBs with a copper lamination >250 µm on the outer layers. Iceberg® structures are also suitable as heat sinks for power components and can be combined with plated-through holes (vias) to optimize thermal management. In a wiring layer there are areas with 70 to 105 µm copper for the control electronics and areas with 400 µm copper for the load. This offers the possibility of combining large cross-sections for high currents and fine conductors in a multilayer with optional inner layers. On the inner layers, the Iceberg® principle can also be combined with thick copper.
The advantages of Iceberg® technology are:
- Production and processing with common materials on base copper in standard processes
- Use of standard materials/technologies
- High currents and heat spread in the printed circuit board
Recommendations for the layer structure
- Use filled thermostable base materials with low Z-axis expansion,
- Calculating the degree of resin filling – material-dependent pre-calculation using the layer build-up program at KSG,
- Use sufficiently resin-rich prepregs,
- Avoid stacked copper surfaces and copper-free areas,
- Evenly distribute copper surfaces and copper-free areas,
- Fill large copper-free areas with copper,
- produce sufficiently large residual rings in accordance with KSG Designrules.