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1) Temperature gradient 1
If a temperature rises abruptly, each joint of the surface mounting device to the package will have
different temperature.
factor of the material, thus damaging the chip.
ascending rate.
2) Preheating
The temperature of the parts and PCB is adjusted under the melting temperature of the solder to stabilize
soldering and ease a thermal shock.
mounting device.
3) Temperature gradient 2
The upper limit of the ascending temperature is the same as in 1).
necessity to contain the peak temperature and time men tioned in 4) within the specified ranges.
4) Peak temperature and time
In order to minimize damages on the package, the peak temperature and time must be most heeded.
Since the peak time has a direct effect on a drop of package strength and a steam pressure in the package,
it is desired to be kept as low as possible.
pressure increases along with a lapse of time.
coincident point of the above-mentioned allowable range and a solderable range.
represented by upper-limit values, not average values, care should be taken not to exceed the upper-limit
values when setting the conditions.
different mounting methods.
Fig. 9.2
Infrared Reflow and Air Reflow Recommended Conditions
As a result, the package may warp due to a difference in the thermal expansion
The lower limit depends on the activity rate of the reflow unit.
Fig. 6.2 and Fig. 6.3 shows the recommended conditions for the
Therefore, it is necessary to heed the upper limit of an
Generally, set to near the rated temperature of the surface
The peak time is required to be minimized because the steam
The conditions mentioned here are provided at a
40
CBM-202PC-04 User's Manual
The lower limit is determined by
As they are
CITIZEN
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