The Glass Substrate Question: When Will It Replace Copper Clad Laminate?

“When will glass replace copper clad laminate on advanced IC substrates?”

That’s a question many on the heterogeneous integration (HI) side of the semiconductor industry are asking. Unfortunately, the answer is not straightforward.

But before we get to answering that, let’s take an advanced IC substrate (AICS) refresher. In other words, how did we get to the point where glass substrates have become a topic of discussion?

AICS provides a means to connect chiplets and passives with extremely high I/O count to the printed circuit board (PCB). In the process, AICS has facilitated a paradigm shift in packaging technology with the introduction of HI. This revolutionary approach to packaging provides a significantly cheaper alternative to silicon interposer technology, which is limited in the package sizes it can support.

The AICS is built around a fiberglass resin core with copper on both sides. This is known as copper clad laminate (CCL). The CCL facilitates the creation of redistribution layers (RDL) that connect through the substrate core with plated through holes (PTH). The RDLs are separated by organic dielectric layers known as build-up films.