“The number of transistors in an integrated circuit doubles approximately every two years”
A basic chip package is supposed to protect the silicon die and interconnects from mechanical damage while providing thermal and electrical connection to the circuit card (Shameless plug for my previous post: https://www.linkedin.com/pulse/chip-packaging-basics-gil-sharon-onhvc/ ).
Chip packaging is a mature science with plenty of solutions and continuous improvements for new challenges. The drive for smaller and more powerful processors is in constant evolution in Silicon integrated circuit (IC) fabrication.
There is an increased use for thinner and lighter electronics. As the devices get smaller, more capabilities are crammed on silicon dies. This miniaturization brings with it known problems in thermal, electrical, mechanical and electromagnetic engineering.
High power running through circuits drives resistive or Joule heating. Heat is generated from collisions of charge carriers and atoms in the conductor. Electric heaters and ovens use Joule heating intentionally, but it is undesirable in IC design. Hot spots, thermal gradients and general lack of thermal management lead to all kinds of reliability issues. More power and denser circuits also drive a higher heat density and higher demand for thermal management. A recent 2024 (Priority date 2019) patent (https://patents.google.com/patent/US12051668B2/en) from TSMC shows dense Chip-On-Wafer-On-Substrate and Package-on-Package technology that incorporates stiffener ring, lid and overmold options. The thermal management solutions are evolving with recent examples like https://patents.google.com/patent/US20240395655A1/en , https://patents.google.com/patent/US20240030098A1/en and https://patents.google.com/patent/US11652020B2/en from Intel. Texas Instruments has a QFN thermal solution example https://patents.google.com/patent/US20240332119A1/en .
Electromigration caused by smaller interconnects, higher current densities and mixed materials means current flow may degrade interconnects over time. Also, distributing clean power and managing drop/IR is more difficult. “Electromigration will become a more serious issue as hybrid bonding connection pitch shrinks. This is because fraction of the copper (Cu) and dielectric interface resulting from any misalignment will become appreciable as it is hard to always make perfect alignment.“ - IBM https://patents.google.com/patent/US20240387426A1/en . Some mitigation techniques rely on material compatibility “the utilization of indium in the microball structure has demonstrated a considerable improvement in mitigation of electron migration.” – Intel https://patents.google.com/patent/US20240332134A1/en .
“The difference in coefficient of thermal expansion (CTE) between the package substrate and the semiconductor die may produce warpage of the semiconductor package.” – Samsung https://patents.google.com/patent/US12080676B2/en . Sometimes improvements in warpage or delamination come at cost of manufacturing complexity, tighter tolerances, extra steps (etching trenches, filling materials, dummy features). Material changes (high filler content, special resins etc.) may compromise other properties: adhesion, mechanical strength, moisture resistance, dielectric properties. Constant material innovation is needed as materials change to control CTE mismatch . “CTE mismatch can cause a large stress, especially when the semiconductor die is subjected to elevated temperatures. The stress caused by the CTE mismatch can result in a crack and delamination defect,” - TSMC https://patents.google.com/patent/US11621235B2/en . Simulation predicting warpage/stress remains challenging, especially with many interacting layers and non‑linear behavior. (Another shameless plug to my previous post https://www.linkedin.com/pulse/cant-avoid-cte-mismatch-gil-sharon-kiuge/ ).
This is a multi-physics problem
The mechanical stress in caused by CTE mismatch.
CTE mismatch is caused by the use of different materials in the package
Different materials are needed for electrical and electro-migration design
Elevated temperature from higher power exacerbates the problem
Higher power density is part of miniaturization
https://www.nvidia.com/en-us/data-center/h100/
https://newsroom.lamresearch.com/the-ai-revolution-relies-on-advanced-packaging
More powerful ICs continue proving Moore’s prediction. The costs associated with manufacturing and design are increasing at a fast pace. The scale of the problem is apparent with the recent nVidia and US government investment in the struggling chip manufacturer, Intel. TSMC’s new 2nm Fab is supposed to start shipping wafers later this year and Samsung’s 3nm and 2nm lines are close behind. We will soon find out how Yield and reliability for the advanced nodes turn out.
Copyright Gil Sharon September 23, 2025 . All rights reserved.