CBM-202PC User’s Manual
34
CITIZEN
6. SPECIAL REMARKS FOR MOUNTING
6.1 CAUTIONS
As relative humidity gets low, static electricity tends to be charged. Although surface mount type
packages need to be stored in dry environments not to be affected by humidity, there is no worry for
charging as the packages in storage are not subject to friction. However, during handling and mounting to
substrates where friction and electric discharge are likely to take place, the relative humidity is
recommended to be 45 to 75% for prevention of electric charge.
6.2 REFLOW MOUNTING
The pattern on a PCB board has been formed to facilitate soldering with the package lead pins,
where a fixed amount of soldering paste is applied by screen process printing and the package is mounted.
The package is temporarily fixed by surface tension of soldering paste.
Then, with solder being reflowed, the package lead and the pattern on the base board are fitted by surface
tension of the reflowed solder.
Although the design value of the lead joint part pattern on a PCB board varies by soldering paste material,
reflow conditions, etc., the standard level is 1.1 to 1.3 times of the width of a lead pin subject to soldering.
6.3 RECOMMENDED CONDITIONS FOR VARIOUS MOUNTING METHODS
Mounting methods most commonly applied to surface mounting devices are the infrared rays reflow
method, the vapor phase reflow method, and the flow soldering method.
In all of these mounting methods, as the entire part of a package is heated, strong thermal stress is applied
to the package. For reliability assurance sake, therefore, not only temperature of the solder joint part but
also temperature of the package surface need to be controlled. As the recommended mounting conditions,
use package surface temperature for the reflow method and solder temperature as well as dipping time
for the flow soldering method.
The basic understanding of the recommended conditions is explained in Fig. 6.1:
Fig. 6.1
Peak temperature
and time
Package
surface
temperature
Time
Thermal gradient 1
Thermal
gradient 2
Preparatory
heating
Summary of Contents for CBM-202PC Series
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