Lift Shafts of Copper: High Bandwidth Memory and Advanced Packaging

Deep End Era. Engineering with Sankalp · Oct 28, 2026 · 54m

At two in the morning a performance engineer watches a two-thousand-trillion-operation chip sit mostly idle, waiting for memory. Episode one hundred and thirty four explains why large language models hit the memory wall, then builds the answer from the bottom up: DRAM dies thinned thinner than a hair, pierced with thousands of copper lift shafts, stacked twelve or sixteen high and wired to a processor through a slab of silicon. We cover why TSMC's CoWoS packaging became the bottleneck of the AI boom, how a few micrometres of mismatched expansion delayed NVIDIA's Blackwell, why compound yield…