NQ12T50SMA16 Datasheet, PDF (13/15 Pages) SynQor Worldwide Headquarters – 16A Non-Isolated, SMT DC/DC Converter with wide trim

Technical Specification
Non-Isolated
SMT Converter
9.6 - 14.4Vin 16A
hottest junction to the converter's PCB at large. It is about
3^oC/W for converters running at higher output voltage, and
about 4^oC/W for lower voltage converters.
• Rt_Pcb-Amb models the power dissipation from converter
PCB to the air stream. It ranges from about 15^oC/W at
400LFM to about 25^oC/W 100LFM.
• Rt_Pcb-Feet expresses the thermal path from the converter's
PCB though its mounting feet; it is about 3^oC/W.
• Rt_spread models the heat spreading on the PCB to which the
converter is mounted and is largely dependent upon the con-
struction and layout of that PCB.
• T_mount is the temperature of that PCB in the greater vicinity
of the converter.
As is evident, the values for Rt_spread and T_mount will have
great effect upon the thermal operation of the converter. With
Rt_Pcb-Amb being 5 to 8 times as large as Rt_Pcb-Feet, in most
applications these converters will be predominantly cooled via
thermal conduction through their feet. Airflow and T_Amb will
have only a minimal cooling effect.
• Rt_spread should be minimized. Attach the converter to
large copper planes, on multiple layers, with multiple vias
near the mounting feet.
• T_mount should also be minimized. Place the converter far
enough away from other sources of heat on the PCB so that
it is as cool as practical.
• If operation near derating limits is even suspected, thermal
performance should be verified with the unit mounted in its
intended manner and powered in circuit with all neighboring
circuitry active. Attach a thermocouple to the converter's
hotspot as shown in Figures 6, 8, and 10 in the Performance
Curves section.
SURFACE MOUNT INFOR-
MATION
pads. Solder mask should be used to eliminate solder wicking
into the vias.
Pick and Place: The NiQor surface mount modules are
designed for automated assembly using standard SMT pick and
place equipment. The modules have a centrally located induc-
tor component with a flat surface area to be used for compo-
nent pick-up. The units use open frame construction and have a
low mass that is within the capability of standard pick and
place equipment. Those modules however have a larger mass
than most conventional SMT components and so variables such
as nozzle size, tip style, handling speed, and placement pres-
sure should be optimized for best results. A conformal tipped
placement nozzle design is recommended. Coplanarity of bet-
ter than 0.004" (0.1mm) is achieved through the SMT NiQor's
terminal design.
Reflow Soldering Guidelines: Figure H shows a typical
reflow profile for a eutectic solder process. Due to variations
in customer applications, materials and processes, it is not fea-
sible for SynQor to recommend a specific reflow profile. The
customer should use this profile as a guideline only. Since the
NiQor surface mount modules have a larger thermal mass and
lower thermal resistance than standard SMT components, it
may be necessary to optimize the solder reflow profile based
on limitations of the other components on the customer board.
Sufficient reflow time must be allowed to fuse the plating on the
connection to ensure a reliable solder joint. The solder reflow
profile should be confirmed by accurately measuring the SMT
interconnect leads. The guidelines illustrated in figure H must be
observed to ensure the maximum case temperature of 260°C
(exposure for 5 seconds or less) is not exceeded for the NiQor
units.
Maximum Temperature (+210-260^oC)
PCB Layout Considerations: SynQor
recommends that the customer use a non-sol-
der mask defined pad design. The minimum
recommended pad size is 0.074" x 0.122"
(1.88mm x 3.1mm) and the maximum pad
size is 0.095" x 0.140" (2.41mm x
3.56mm), see mechanical diagram on page
2. Interconnection to internal power planes
is typically required. This can be accom-
plished by placing a number of vias between
the SMT pad and the relevant plane. The
number and location of the vias should be
determined based on electrical resistance,
current and thermal requirements. "Via-in-
pad" design should be avoided in the SMT
Eutectic Solder Melting Point (+183^oC)
(+150-155^oC)
Pre-heat
• < 2.5^oC/sec
Soak
• 0.5-0.6^oC/sec
• 60 to 90 sec.,
typ., 2 min max
Reflow
• 1.3-1.6^oC/sec
• 30 to 60 sec., typ.,
90 sec max
2 to 4 min.
Figure H: Typical Eutectic (96.5Sn/3.0Ag/0.5Cu) Solder Profile
Cool Down
Product # NQ12T50SMA16
Phone [phone]
Doc.# 005-2NS12TE Rev. A
5/28/04
Page 13