Customer reference fine-pitch package substrate

Camera-based advanced driver assistance systems (ADAS) are one focus of Dream Chip Technologies. In this area, the system developer has created a new type of chip design for image processing. This makes possible applications such as automatic object detection, e.g. for pedestrians or traffic signs, or a high-resolution 360° all-round view.

The technological basis for the system is the 22 nm FD-SOI technology as well as convolutional neural networks. They permit the recognition of image data in real time and automatic classification based on an existing data basis. Particularly high processing power is required here for image and video processing. The multifunctional system-on-chip (SoC) is based on a processor architecture with four cores and two memory units.

The architecture of the system was particularly challenging in the implementation of this ADAS chip. The microchip is situated along with the two memory units on a particularly high-performance circuit board. Fraunhofer IIS/EAS assisted Dream Chip in this project by developing the fine-pitch package substrate, which has never been manufactured for such an application before.

It was necessary to realize the large number of exceptionally densely packed connections of the SoC – a total of 1,500 connections spaced at 150 µm. To solve this problem, the scientists developed a circuit board with 8 layers in which the vias are implemented as stacked vias. The spacing of the interconnects, which is 100 µm line/space in other chip designs, was also reduced to 30 µm line/space and the diameter of the vias was kept very low at 110 µm.

In addition, Fraunhofer IIS/EAS optimized the memory connection by not running all interconnects entirely through the substrate; instead, some run directly to the memory units via the circuit board. This made it possible to meet the requirements on the chip design with regard to speed, low power consumption and short signal length. In addition, the support of the division in the system design helped make possible a small volume production within a fixed production schedule.