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Chip-scale power transistor packaging

By Shaun Bowers [Amkor Technology, Inc.]
E xpanding applications for

advanced power packaging
have created the need for new
package design concepts to
fill the gaps between existing discrete and
power module designs. The integrated
power market continues to expand and
evolve with established and advanced
power semiconductor technologies.
Understanding the current environment
and the challenges of moving forward are
necessary to embrace a new integrated Figure 1: Available power discrete capabilities include: a) PQFN evolution, b) eD2PAK with heat spreader tab, c)
power packaging technology. TOLL variations, and d) LFPAK.
to leadless SMDs, to SMDs with dual- they have created new challenges and
The evolving power electronics market sided cooling and chip-scale metal-oxide- opportunities for power packages.
Telecom, data centers, electric and semiconductor field-effect transistors With lower losses, a given size power
hybrid electric vehicles, and wireless (MOSFETs). Current options to address device can control higher power loads.
power are among the current applications these requirements include power quad For example, with GaN power transistors,
driving advanced power electronic flat no-lead (PQFN), routable lead frame a power system can have ¼ the size,
designs. The global data center power and a host of discrete solutions including weight and efficiency losses compared to
market alone is expected to grow at a exposed double-decawatt package a silicon-based system. GaN technology
compound annual growth rate of 12% (eD2PAK), TO-leadless package (TOLL) can solve the system challenges from
from 2019 to 2025 to reach approximately and loss-free package (LFPAK). Figure the low-power (50W) end to medium-
$1 billion by the end of that period [1]. 1 shows examples of existing discrete and even high-power levels in wireless
However, DC-DC conversion, DC-AC power packaging and the evolution systems and more. Its acceptance in 5G
conversion and simple power switches of PQFN packaging. Table 1 shows a applications makes it well-positioned
are required for all electronic products. comparison of different characteristics of for sophisticated low- to medium-power
Improving power electronics in today’s these packages. packaging. Similarly, SiC has power
designs requires: control capabilities beyond those of
Si MOSFETs and requires advanced
• Lower resistance/inductance; packaging for many applications. The
• Integrated controller/logic/passive gains and advantages in WBG devices
components; and need new packaging options to maximize
• Reduced form factor. the value of the entire power system.
I ndu st r y st a nd a rd s a re a mong
Low on resistance (R DS(on) ), as well as the ongoing developments that can
low inductance (L DS ), are necessary to accelerate the adoption of SiC/GaN
achieve low switching losses in power power technologies. This is the focus
circuits. Without proper attention to these of the JEDEC Solid State Technology
design details, the package must handle Association’s JC-70 committee that
even greater power losses or address was started in 2017. With the recent
lower power application because its power Table 1: Comparative data on existing power packages. publication of JEP180, “Guideline
capabilities are restricted. Integrating the Wide-bandgap (WBG) semiconductor for switching reliability evaluation
controller has become more common with technologies, such as silicon carbide procedures for gallium nitride power
the availability of numerous power control (SiC) and gallium nitride (GaN), conversion devices [2],” to ensure the
integrated circuits (ICs). Available space have a higher figure of merit (FOM) inherent robustness of GaN devices
in any end design is always at a premium, compared to silicon MOSFETs and have in power conversion applications, the
so a reduced form factor is a must. extended the efficiency, output power interest in innovative packaging should
To address increasingly tougher system and/or switching frequency range increase. An ongoing discussion of JC-70
design goals, power discrete packaging and operating temperature range for with automotive-related organizations is
has progressed from through-hole to power electronics. At the same time, also in progress.
surface mount devices (SMDs) with leads,

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