PRELIMINARY
Application Information
V鈥 Chip soldering recommendations
V鈥 Chip modules are intended for reflow soldering processes. The
following information defines the processing conditions required for
successful attachment of a V鈥 Chip to a PCB. Failure to follow the
recommendations provided can result in aesthetic or functional failure
of the module.
Storage
V鈥 Chip modules are currently rated at MSL 5. Exposure to ambient
conditions for more than 48 hours requires a 24 hour bake at 125潞C
to remove moisture from the package.
Solder paste stencil design
Solder paste is recommended for a number of reasons, including
overcoming minor solder sphere co-planarity issues as well as simpler
integration into overall SMD process.
63/37 SnPb, either no-clean or water-washable, solder paste should be
used. Pb-free development is underway.
The recommended stencil thickness is 6 mils. The apertures should be
20 mils in diameter for the Inboard (BGA) application and 0.9-0.9:1 for
the Onboard (J-Leaded).
Pick and place
Modules should be placed within 鹵5 mils.to maintain placement
position, the modules should not be subjected to acceleration greater
than 500 in/sec
2
prior to reflow.
Reflow
There are two temperatures critical to the reflow process; the solder
joint temperature and the module鈥檚 case temperature. The solder joint鈥檚
temperature should reach at least 220潞C, with a time above liquidus
(183潞C) of ~30 seconds.
The module鈥檚 case temperature must not exceed 208 潞C at anytime
during reflow.
Because of the
螖T
needed between the pin and the case, a forced-air
convection oven is preferred for reflow soldering. This reflow method
generally transfers heat from the PCB to the solder joint. The module鈥檚
large mass also reduces its temperature rise. Care should be taken to
prevent smaller devices from excessive temperatures. Reflow of
modules onto a PCB using Air-Vac-type equipment is not recommended
due to the high temperature the module will experience.
Inspection
The solder joints should conform to IPC 12.2
鈥?Properly wetted fillet must be evident.
鈥?Heel fillet height must exceed lead thickness plus solder thickness.
Figure 23鈥?/div>
Properly reflowed V鈥 Chip J-Lead
16
Soldering Time
V鈥 Chip Pre-Regulator Module
Removal and rework
V鈥 Chip modules can be removed from PCBs using special tools such
as those made by Air-Vac. These tools heat a very localized region of
the board with a hot gas while applying a tensile force to the
component (using vacuum). Prior to component heating and removal,
the entire board should be heated to 80-100潞C to decrease the
component heating time as well as local PCB warping. If there are
adjacent moisture-sensitive components, a 125潞C bake should be used
prior to component removal to prevent popcorning. V鈥 Chip modules
should not be expected to survive a removal operation.
239
Joint Temperature, 220潞C
Case Temperature, 208潞C
183
165
degC
91
Figure 22鈥擳hermal
profile diagram
vicorpower.com
800-735-6200
V鈥 Chip Pre-Regulator Module
P048F048T24AL
Rev. 1.7
Page 13 of 14
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