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CBM-202PC-04 User's Manual
If a relative humidity drops, the LSI will be electrified with static electricity more easily.
The surface
mounting package must be stored in a dry atmosphere to prevent humidity absorption, but while it is being
stored, it will not be electrified because it will not have friction, etc.
When handling or mounting it onto the
PCB where friction or electric discharge may be expected, the relative humidity is desired to be 45~75%
from a viewpoint of prevention of electrification.
Using the screen printing method, etc., apply a constant amount of solder paste to the pattern on the PCB,
which was formed into the specified shape required for soldering the lead pins to a package mounting section,
and mount the package onto it.
It will be temporarily fixed by the surface tension of the solder paste.
Then, if the solder is melted(reflow) again, the leads of the package and the pattern of the PCB will be
matched by a self-alignment effect through the surface tension of the molten solder.
Although the lead joint pattern design values of the PCB depend on the solder paste material used, reflow
condition, etc., they should be preferably 1.1~1.3 times larger than a soldered lead pin width.
The most common mounting methods employed for the surface mounting devices are the infrared reflow
method, vapor phase reflow method, and flow solder method.
As all of those mounting methods must heat
the entire package and apply a strong thermal stress, they require you to manage not only a temperature at the
solder joints, but that on the package surface, from a viewpoint of maintenance of reliability.
Therefore, the
recommended mounting conditions are given in terms of the package surface temperature for the reflow
method, and in terms of solder temperature and immersion time for the flow solder method.
The following describes the concepts of the recommended conditions, using Fig. 9.1.
Fig. 9.1
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