Critical Aspects of High-Performance Microprocessor Packaging

Abstract

Historically, the primary function of microprocessor packaging has been to facilitate electrical connectivity of the complex and intricate silicon microprocessor chips to the printed circuit board while providing protection to the chips from the external environment. However, as microprocessor performance continues to follow Moore's law, the package has evolved from a simple protective enclosure to a key enabler of performance. The art and science of semiconductor packaging has advanced radically over the past few decades as faster and more powerful microprocessors with tens of millions of transistors continue to be available, which require more signal and power input/output connections as well as greater power-dissipation capabilities. Key drivers for the development of packaging technologies include power delivery, thermal management, and interconnect scaling, in which the space transformation from fine-featured silicon interconnects to the relatively coarse features seen on motherboards has to be enabled by the package. These drivers, under constant market-driven cost pressure, have led to increased demands on new materials and new package architectures to enable silicon performance. Significant advances have already been made in the areas of heat dissipation, power delivery, high-speed signaling, and high-density interconnects. It is expected that the future evolution of microprocessors will be increasingly challenging in these areas. This article focuses on providing a broad perspective view of the evolution of microprocessor packaging and discusses future challenges.

Residual stress and interfacial reaction of the electroplated Ni-Cu alloy under bump metallurgy in the flip-chip solder joint

“…1a were measured using a wafer curvature measurement by laser scanning and the Stoney equation under the thin-film approximation. 33 (1) where σ f is the biaxial film stress, Y s is the biaxial modulus of the substrate, K is the curvature, and t f and t s are the thickness of the film and the substrate, respectively. The specimens for stress measurement were 2.5 cm ϫ 2.5 cm.…”

“…A greater number of I/Os is required for the faster electronic devices, such as the central processing unit of a computer. 1 The lower inductance for low loss of data signal is required for high frequency network devices, such as monolithic microwave integrated circuits. 2 Thinner devices are required for mobile electronics, such as notebook computers, cellular phones, and personal digital assistants.…”

Singular stress fields at corners in flip-chip packages

“…These organic substrates have a lower dielectric constant, have smaller thermal mismatch with the mother board, and are easier to process metallization. [1] Nevertheless, the organic substrates have several disadvantages, such as adsorption of moisture, large thermal mismatch with the silicon chip, severe warpage during assembly. [2,3] As a result, novel ceramic substrates have also been developed; for example, Low Temperature Co-fired Ceramic (LTCC), a ceramic-glass composite with elastic and thermal properties comparable to those of silicon, is a potential choice for the substrate.…”

Fully integrated one phase liquid cooling system for organic boards

“…The advantages are obvious and well-known [4]. So are the disadvantages [5,6]. Especially reliability and cost are key blockers against the large scale employment of liquid cooling solution for costperformance, microprocessor or graphic-processing applications, whereas there is activity on the high performance sector [7,8].…”