MLN Datasheet, PDF (5/7 Pages) Littelfuse – Multiline Transient Voltage Surge Suppressor

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Surface Mount Varistors
Multiline Transient Voltage Surge Suppressor
MLN SurgeArray^™ Suppressor
Typical Performance Curves Any Single Section (Continued)
10000
1000
100
10
3
1
0.1
1MHz
10MHz
100MHz
FREQUENCY
FIGURE 10. IMPEDANCE vs FREQUENCY
1GHz
10GHz
0
-20
-40
-60
-80
-100
-120
1kHz
V_IN = 1V_RMS
Z = 50Ω
10kHz
100kHz
1MHz
FREQUENCY
10MHz
FIGURE 11. ADJACENT CHANNEL CROSSTALK
100MHz
1GHz
Soldering Recommendations
The principal techniques used for the soldering of components in surface
mount technology are Infrared (IR) Reflow, Vapour Phase Reflow, and
Wave Soldering. Typical profiles are shown in Figures 12, 13 and 14.
When wave soldering, the MLN suppressor is attached to the circuit
board by means of an adhesive. The assembly is then placed on a con-
veyor and run through the soldering process to contact the wave. With IR
and Vapour Phase Reflow, the device is placed in a solder paste on the
substrate. As the solder paste is heated, it reflows and solders the unit to
the board.
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 flux.
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 reflow 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 solders peak
temperature is essential to minimize thermal shock. Examples of the sol-
dering conditions for the MLN array of suppressors are given in the
tables below.
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 gradually cool to less than 50^oC before cleaning.
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