Troubleshooting Tips: IC – WCSP Handling

When you see any
TI device, it is necessary to follow
the information in the data sheet, which
you can download on TI.com. In this video, I will talk about
WCSP devices and the proper way to remove ’em. Today, I will be covering
what a WCSP package is, what can happen if a WCSP
package is mishandled, the proper way to remove
WCSP devices from boards, the proper ways of packing
them once they are removed, and lastly, incorrect
practices that should always be avoided when packing
and shipping devices. WCSP stands for wafer
level chip scale package. There are many advantages
to this type of package. For instance, the package
size is equal to a die size, and is the smallest
footprint per aisle. However, this type
of package does not have a protective
mould compound, which means that special
precautions need to be taken when removing from my board. If a WCSP device is
improperly removed, it may result in damage
that may propagate into the active circuitry,
and therefore making FA no longer possible. In order to properly
remove WCSP devices, a hot air rework machine and
an ESD-safe vacuum pencil are needed. Never use tweezers to
handle WCSP devices, as they may cause
damage to the device. The following is
the correct method for removing lead-free ball
WCSP devices from the board. Select the
appropriate IC profile according to the device
that is being de-soldered. The device’s data sheet
includes the needed specs. Protect the
temperature-sensitive components–
specifically plastic– and remove any batteries
from the board. Aluminum foil can be
used for shielding. Place flux around
the IC on the board. Ensure the flux is
coated all around see so that it can flow
under the component. Place the PCB on
the machine plate. Ensure the thermocoupler is
as close as possible to the IC to get correct
temperature readings. Align the nozzle with
direction of the laser to the center of the IC. And lastly, please
start on the software. Do not be concerned with
solder bump conditions. The units will be re-balled
by Texas Instruments after visual inspection
of the return device. Now, let’s talk about what
to do once the devices have been removed and are
now ready for packing. Never use tape, and stick the
device to paper Post-It notes to pack WCSP devices. Also, do not put loose
devices in an ESD bag. Always use the recommended
carrier foam or waffle pack. After the devices
have been removed, ensure that only
foam or waffle packs are used to pack these devices. Foam packs should only
have one unit per pack to avoid physical contact of
units during transportation. Make sure that if a
waffle pack is used, it must be sized correctly to
prevent damage during shipment. It’s important to utilize
the TI datasheet when it comes to WCSP devices, and
the proper way to remove them. For TI datasheets, visit
TI.com, and thanks for watching.

Bernard Jenkins

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