Moisture Sensitive Devices
||Moisture Sensitive Devices (MSDs),
must be managed correctly because "a single mistake" on a
tray or reel of MSD causes "negative impact on the entire
Electronic components (like QFP, BGA or SOIC for example),
LEDs and Printed Circuit Boards, when extracted from their
original protective package, absorb humidity from the
environment and during the soldering process the trapped
moisture can vaporize and exert internal package stress.
Possible damages are: package cracking (popcorn),
interfacial delamination, thermal or electrical connection
interrupted and possible long-term corrosion.
most important international standard concerning the
J-STD-033 "Handling, Packing, Shipping and
Use of Moisture/Reflow Sensitive Surface Mount Devices"
SMD components are classified into moisture sensitivity
levels from 2 to 6. A higher level means more
sensibility to the absorbed humidity during the
The standard specify how to pack SMD components and, in
particular, from level 2a to 5a it's required a Dry
Pack: desiccant material and a Humidity Indicator Card
sealed with the SMD packages inside a Moisture Barrier
Bag. Every component has a limited time period (Floor
Life) after removal from the Dry Pack and before the
solder reflow process. Exceeded this allowable time
period it's necessary to bake the component at 40°C,
90°C or 125°C.
IPC-1601 "Printed Board Handling and
It provides indications about handling, packing, storage
and baking of laminates and printed circuit boards (PCB)
both to manifacturers and assemblers of PCB.
Dry cabinets provides a "safe
place" to temporary stock the MSDs removed from their
original Dry Pack before soldering process.
In fact the J-STD-033 tells that under 5% RH the Floor
Life is congealed.
Some cabinets version shown on pages 70-71 can do 40°C
low baking process of SMD components.
At this temperature the reels are not damaged and can be
afterwards inserted into the feeders of the pick and
place without problems.
According to the IPC-1601
baking of the PCBs should be done at 105-125°C for 4-6
hours into a forced air recirculating oven.
For SMD components the J-STD-033 specify three
temperature: 40°C, 90°C and 125°C.
How long to bake depends on the moisture sensitivity
level and package type and body thickness.
In the worst case is 79 days for 40°C baking, 10 days
for 90°C baking and 96 hours for 125°C baking.
Once baked MSDs have their Floor Life restored to the
It's convenient to use a programmable oven. All our
ovens have timer, programmable start-up, datalogger
(useful for traceability). In addition they can execute
thermal program useful for testing and for
heating/cooling with settable temperature gradient
After reels extraction from their
Dry Pack and partial assembling and soldering of the
components, what to do with the left parts?
The ideal solutions are to solder them immediately
before Floor Time expiration or to store them into a dry
In alternative it is possible to seal them again into a
new Dry Pack like the one shown above.
To seal the moisture barrier bag it is needed a heatsealers.