Enhancing Thermal Performance of CSP Integrated Circuits


Reading time ( words)

In the portable electronics market, power management integrated circuits (PMICs) are increasingly found being packaged into ball grid array (BGA) and chip scale packages (CSP) for their lower material costs, improved electrical performance (no bond wire impedances), and smaller form factors. These advantages do not come without compromise: The silicon die of CSPs are no longer in direct contact with large heat-spreading thermal paddles (E-PADs) used for electrical and thermal conduction.

This is the primary performance trade-off; because the IC substrate is not in contact with an E-PAD there is no high-conductivity direct thermal connection from the substrate to the heat-spreading copper planes on the PCB. This article will discuss PCB level methods that will lower the operating temperature of CSP devices by examining methods to transfer heat from the source and transport it to the ambient environment by lowering thermal resistance of the CSP IC. There are usually multiple ways to enhance the performance while simultaneously lowering the operating temperature that can be incorporated into new boards or revisions of existing boards.

In order to meet size and weight requirements, constraints of portable electronic designs often force PCB designers to reduce the size of components and PCB real estate area. To meet these demands, the use of CSP packages to shrink the PCB area needed is a common change in designs. As a result of the reduction of total PCB area, the available options to move heat and route high-power PCB traces is also reduced. Furthermore, the thermal performance cannot be matched when a QFN is compared to an equivalent CSP package; therefore, it is imperative that the PCB is designed to optimize heat transfer from the CSP to the PCB, which in turn dissipates it into the atmosphere. The parameter measuring the heat conductivity is the junction-to-ambient thermal resistance specification, Theta-JA (ӨJA (˚C/W)).  

To read this entire article, which appeared in the January issue of The PCB Design Magazine, click here.

Share

Print


Suggested Items

Why We Simulate

04/29/2021 | Bill Hargin, Z-zero
When Bill Hargin was cutting his teeth in high-speed PCB design some 25 years ago, speeds were slow, layer counts were low, dielectric constants and loss tangents were high, design margins were wide, copper roughness didn’t matter, and glass-weave styles didn’t matter. Dielectrics were called “FR-4” and their properties didn’t matter much. A fast PCI bus operated at just 66 MHz. Times have certainly changed.

DFM 101: PCB Materials

04/30/2021 | Anaya Vardya, American Standard Circuits
One of the biggest challenges facing PCB designers is understanding the cost drivers in the PCB manufacturing process. This article is the first in a series that will discuss these cost drivers (from the PCB manufacturer’s perspective) and the design decisions that will impact product reliability.

Eliminating ‘Garbage In, Garbage Out’ With Checks and Balances

03/26/2021 | Nick Barbin, Optimum Design Associates
The proverbial saying “garbage in, garbage out” holds true in the electronic product development world. PCB designers stand squarely in the middle of a busy information intersection flowing with inputs and outputs. Missing or bad information at the beginning of a design project will undoubtedly lead to board re-spins, increased costs, and most importantly, a delayed product release. The same can be said about the PCB designer who doesn’t provide a fully checked and comprehensive data package to the downstream manufacturers, i.e., “throwing it over the fence.”



Copyright © 2021 I-Connect007. All rights reserved.