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CSPLeadless-QFN
Product
Overview
QFN
Based on copper lead
frame, Quad Flat No-lead (QFN) or microchip carrier
(MCC) uses half-encapsulation technology to expose
the rear side of the die pad and the tiny fingers,
which are used to connect the chip and bonding wire
with the PCB. QFN packages are suitable for applications
of over 12GHz working frequency. Providing both
thermal and electrical en-hancement, QFN is a cost-effective
packaging solution due to its economical materials
and simpler packaging process.
Application
Telecommunication
products
Cellular phones
Wireless LAN
Portable
products
Personal digital assistants
Digital cameras
Low
to medium lead count packages
Information appliances
Features
Small footprint
Low profile (<0.9 mm)
Light weight
Cost effective
Better electrical performance
Better power dissipation
Reliability
*Depends on PKG Size.
Performance
Electrical
The electrical data about leadless packages is variable. Two components - the bond wire and terminal can affect the electrical parasitic. Apparently, the effect from the terminal is trivial. Therefore, the electrical parasitic (mostly from the inductance) can be simply estimated by calculating the wire length. The empirical RLC values for gold wire in 25um diameter are 50mW /mm, 1nH/mm, and 0.06 pF/mm.
Max
Trace
QFN
(MCC) (Basd on Max. trace. Data marked
with "s" are derived from simulation.)
F=100MHz
Pad size
3x3 16L
1.7x1.7
4x4 24L
2.7x2.7
5x5 32L
3.7x3.7
7x7 48L
5.7x5.7
8x8 56L
6.7x6.7
9x9 64L
7.7x7.7
Thermal
Characterization
For QFN, the exposed
die pad has to be soldered to the PCB to maintain
its thermal performance. Little improvement is found
if the pad is floating. Contact ASE R&D for
details.
Small footprint