Packaging: then, now and in the future.

Packaging has evolved from the role of primarily protecting the chip to one of overall system integration of heterogeneous chiplets. An important aspect of this integration is miniaturization. Feature sizes such as substrate wiring pitch, die-to-substrate bonding pitch, and inter-die distances need to shrink in a predictable manner to approach monolithic wiring pitches, last level via pitches and IP block spacings. We refer to this as shrinking down of the package. Simultaneously, we need to increase the number of dies interconnected on the package to improve performance and functionality. We refer to this as scaling out of the package. Current approaches to this include additional levels in the packaging hierarchy with concomitant increases in complexity and cost. We need to think of new ways of flattening the packaging hierarchy by enabling substrates with finer wiring pitches and the ability to assemble dies at fine pitch at high throughput. Besides the technology and processes needed to accomplish this, there are other difficult issues that need to be addressed: these include power delivery and thermal dissipation, high bandwidth, and potentially active wired, wireless, and photonic connectors to the external world or between subsystems. Finally, to make this vision a reality a chiplet eco system needs to be developed with mechanical and electrical standards that ensure interoperability and a high level of reuse. Similarly, a comprehensive EDA approach needs to be developed that goes well beyond electrical abstraction of the system and includes among other things thermal, thermomechanical considerations, power delivery, test methodology and reliability. This is a challenging opportunity and promises to continue the trend set by Moore’s law, for system integration.