Download Surface Mount Package User`s Manual

• SOP-28 pins
Solder bath: 245°C
Dip time: 4 seconds
(The temperature is measured at the
surface of the printed wiring board.)
4 seconds
235°C
Temperature
Preheat approximately 60 seconds.
120°C
Board surface
temperature
Enters the solder
Exits the solder
Time
Figure 3.40 Example Temperature Profile for Flow Soldering Method
Note that the applicability of this process depends on the individual products; contact your service
representative directly to check the applicability of this process to your products.
When the flow soldering method is used, there are even greater temperature differences within the
IC itself depending on the thermal capacity of the packages than there are using reflow methods
such as IR reflow. This is because the heat that reaches the IC comes from direct thermal
transmission from contact with the molten solder.
One method that is commonly used in experimenting with the thermal durability to flow soldering
method is that of immersing the IC which is not mounted on a board into the solder bath.
However, although this method is both convenient and easy to perform, because all surfaces of the
package directly contact the molten solder, the temperature within the IC will be higher than it
would were the IC mounted on a board used as it is in actual practice, and thus the stresses exerted
on the package will be larger. Consequently, we would suggest that when thermal durability
testing is performed relative to the flow soldering method, it should be performed using ICs that
are actually mounted on boards in order to insure testing conditions more closely resembling the
actual conditions of use.
60