Overview of HDI/SBU technology
HDI stands for »High Density Interconnect«. These are Multilayer-PCB assemblies with four or more levels, which are sequentially assembled with several pressing cycles ("Sequential Build Up" or SBU). This achieves higher packing densities and meets the requirements of the latest component development. That means completely new possibilities for your PCB layout. Opportunities to accommodate the ever-increasing miniaturisation that demands increasingly complex circuits and components with extremely high pin counts.
Thanks to state-of-the-art production technology, layouts are possible from a line/space of 75 µm. Via filling technologies such as microvia-copper-filling, plugging or resin filling play a decisive role in the choice of the best strategy for rewiring.
- Maximum packing densities, miniaturisation and the optimum use of space
- Greatest possible freedom of component placing
- Reduction in track lengths and improved EMC behaviour of the assembly
- Simplified routing of the PCB layout
- Reduction of number of layers
- Dense, single-sided assembly, with a corresponding reduction in assembly costs
The individual components can be electrically connected to each other and consequently rewired in a relatively complex manner by means of various drilling technologies using sequentially multi-pressed multilayers (SBU). As a result, inner layers can be connected and unbundled without blocking the space for board components with high pin density on the outer layer.
In addition to plated through holes, laser vias and internal holes (buried holes) are used for the connection to and on the inner copper layers. In the case of a higher number of layers in combination with HDI-design, PCB base material with optimised Z- axis expansion is recommended.
Solder resist masks
- Photosensitive coating systems, thermal final curing
- Colours: green, red, blue, glossy black, matt black, white, yellow
- Non-photosensitive coating systems, purely thermosetting: white, black
- Chemical nickel/gold
- Chemical tin
- Electroplated nickel/gold
- HAL or HAL lead-free
- others on request
- Hole filler/through hole filler
- Peelable solder mask
The end faces of the PCB contour can be plated in order to improve the EMC protection of a PCB, make electrical contact with the housing of the module or meet increased cleanliness requirements.
Milled plated through holes
It is possible to produce application-specific components with so-called milled plated through holes. Due to the possibility of contact on the front side, the resulting PCBs can be soldered as components to another board (interposer).
Contour production: milling and scoring
|Number of layers||≤ 30|
|PCB thickness||0,5 mm - 3,20 mm|
|Glass transition temperature||(135), 150°C, 170/180°C|
|Advanced technologies (see structure variants)||Viafilling Typ VII Microvia-Copper-Filling |
The values specified represent the maximum performance spectrum and may be restricted in certain combinations.
Microvias (lasered) on outer layers
Microvias (lasered) in combination with plated-through laminates (mechanically drilled)
Microvias (lasered) in combination with buried vias (mechanically drilled)
Staggered microvias (lasered) in combination with buried vias (mechanically drilled) – from L2 to Ln-1
Staggered microvias (lasered) in combination with buried vias (mechanically drilled) from L2 to Ln-1
Stacked microvias (lasered) with microvia-copper-filling in combination with buried vias (mechanically drilled)
If you have any questions about the topic, we are happy to be your contact person.