Littelfuse MLN SurgeArray Suppressor - Manual (Page 4)

© 2013 Littelfuse, Inc. 66
Revised: October 9, 2013
Varistor Products
MLN SurgeArray™ Suppressor
Surface Mount Multilayer Varistors (MLVs) > MLN Series
Specifi cations are subject to change without notice.
Please refer to www.littelfuse.com/series/MLN.html for current information.
Lead (Pb) Soldering Recommendations
The principal techniques used for the soldering of
components in surface mount technology are IR Re-fl ow
and Wave soldering. Typical profi les are shown on the right.
The recommended solder for the MLN suppressor is
a 62/36/2 (Sn/Pb/Ag), 60/40 (Sn/Pb) or 63/37 (Sn/Pb).
Littelfuse also recommends an RMA solder fl ux.
Wave soldering is the most strenuous of the processes.
To avoid the possibility of generating stresses due to
thermal shock, a preheat stage in the soldering process
is recommended, and the peak temperature of the solder
process should be rigidly controlled.
When using a refl ow process, care should be taken to
ensure that the MLN chip is not subjected to a thermal
gradient steeper than 4 degrees per second; the ideal
gradient being 2 degrees per second. During the soldering
process, preheating to within 100 degrees of the solder's
peak temperature is essential to minimize thermal shock.
Once the soldering process has been completed, it is
still necessary to ensure that any further thermal shocks
are avoided. One possible cause of thermal shock is hot
printed circuit boards being removed from the solder
process and subjected to cleaning solvents at room
temperature. The boards must be allowed to cool gradually
to less than 50ºC before cleaning.
PREHEAT ZONE
PREHEAT DWELL
RAMP RATE
<2°C/s
MAXIMUM TEMPERATURE
230°C
TEMPER
A
TURE °C
TIME (MINUTES)
250
200
150
100
50
0
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
40-80
SECONDS
ABOVE 183°C
TIME (MINUTES)
300
250
200
150
100
50
0
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
MAXIMUM WAVE 260°C
SECOND PREHEAT
FIRST PREHEAT
TEMPER
A
TURE °C
Refl ow Solder Profi le
Wave Solder Profi le
Figure 10
Figure 11