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Figure 7: Wettable flank addresses critical needs of the automotive original equipment manufacturers’s (OEM’s) manufacturing process.
The flip-chip capability of the MLF to extend into high-power applications a leadless package and the automotive
technology enables size reduction while and meet the very demanding market industry requires a visible indicator of a
improving electrical signal integrity requirements ranging from automotive reliable solder joint post reflow, the need
and thermal performance. Applications to consumer gaming products. for an inspectable solder fillet on each lead
such as power management integrated New material sets specifically target is mandatory. This is especially important
circuits (PMICs) and radio frequency zero delamination and the demanding in automotive applications where each
(RF) are early adopters of the leadframe automotive reliability requirements of PCB is inspected using automated
flip-chip solution. Typical flip-chip MLF the Automotive Electronics Council’s optical inspection (AOI) equipment. The
technology designs today that utilize AEC-Q100 and AEC-Q006 standards. formation of a solder fillet on each lead
Cu pillar bumping can have 160µm These material sets have also extended that can be detected by the AOI equipment
bump arrays. RF devices rated up to the use case of this technology to is critical to the automotive OEM’s
40GHz utilize this type of packaging applications previously dominated by manufacturing process. MLF packaging
solution in applications ranging from leaded-package solutions such as QFPs solutions form the fillet using a process
smartphones to high-speed servers. The and small outline integrated circuit (SOIC) known as step cut in the saw singulation
use of a Cu leadframe enables thermal designs. Roughened leadframe finishes, process, or the dimple when punch
performance in excess of 4 watts, improved epoxy die attach materials, film singulation is applied. Both processes
making this technology ideal for the die attach for automotive applications enable the formation of a fillet necessary
battery management systems in wireless/ and improved molding compounds to for indicating proper wetting of the leads
handheld applications. Adaptation of the enhance Cu wire performance are only a and both processes are widely utilized in
flip-chip MLF is occurring in automotive few of the enhancements that are being the automotive industry today.
applications as well. As the battery applied to extend the value of the MLF
electric vehicle (BEV) market grows, packaging technology. Considering the Summary
more focus is being placed on size and ever-rising increase in the price of Au, The MLF/QFN technology is a market
weight of the electronics in the vehicles. more than ever IC packaging solutions adaptable and cost-sensitive technology.
Battery management controllers today are need alternatives for interconnects. The Utilizing the flexible form factor and
predominately hard wired into the battery automotive industry has been reluctant to adaptable interconnect capabilities in
cell. The transition to wireless control adopt Cu wire too quickly primarily due combination positions this packaging
solutions will require more devices, so, to issues seen regarding long-term latent technology to meet a multitude of market
having small, low weight packaging failures of the wire bonds attributed to needs and application requirements.
solutions is of paramount interest. interactions of the mold compound and
The exposed die attach pad (either the Cu wire. Innovations in both the wire Acknowledgments
top or bottom, or both) feature enables and mold compounds have resulted in the MicroLead Frame and M LF are
this packaging technology to meet the much-improved performance seen with registered t rademarks of A m kor
thermal needs of high-performance respect to the reliability requirements and Technology, Inc.
networking devices as well as power have led to a broader adaptation of Cu © 2022 Amkor Technology, Inc. All
devices. The ability to integrate large- wire for automotive ICs. rights reserved.
diameter bond wires and Cu clips for One of the key recent innovations with
power field-effect transistors (FETs) respect to MLF technology is the wettable
has enabled MLF packaging solutions flank (Figure 7). Because the MLF is

Biography
®
Marc Mangrum is Sr. Director for MLF Products at Amkor Technology, Inc. Tempe, AZ. Prior experience
includes more than 30 years at Motorola and Freescale. His capabilities include the development of advanced
ATE for digital/analog ICs, and cost-reducing IC package design and assembly processes. He has published over
30 papers and has 33 patents issued, and is a graduate of the U. of Texas at Austin with core competencies in
mathematics, electrical engineering, and business administration. Email Marc.Mangrum@Amkor.com

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