V120MLA0402LWA 데이터 시트보기 (PDF) - Littelfuse, Inc
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V120MLA0402LWA Datasheet PDF : 11 Pages
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Surface Mount Varistors
Multilayer Transient Voltage Surge Suppressors
ML Varistor Series
Soldering Recommendations
The principal techniques used for the soldering of components in surface
mount technology are Infrared (IR) re-flow, vapour phase re-flow and wave
soldering. Typical profiles are shown in Figures 14, 15 and 16. When wave
soldering, the ML suppressor is attached to the circuit board by means of an
adhesive. The assembly is then placed on a conveyor 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 re-flows and solders the unit to the board.
The recommended solder for the ML 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. For 0402 size devices, IR
re-flow is recommended.
When using a reflow process, care should be taken to ensure that the ML
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. Examples of the
soldering conditions for the ML suppressor 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 cool gradually to less than
50oC before cleaning.
Termination Options
Littelfuse offers three types of electrode termination finish for the
Multilayer product series:
1. Silver/Platinum (standard, not available for 0402)
2. Silver/Palladium (optional)
(The ordering information section describes how to designate them.)
3. Nickel Barrier (optional for 0402-1210 package size)
(The ordering information section describes how to designate them.)
250
MAXIMUM
TEMPERATURE 222oC
200
40-80
SECONDS
ABOVE 183 oC
150
RAMP RATE
<2oC /s
100
PREHEAT DWELL
3
50
PREHEAT ZONE
0
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
TIME (MINUTES)
FIGURE 14. REFLOW SOLDER PROFILE
300
MAXIMUM WAVE 260 oC
250
200
150
SECOND PREHEAT
100
FIRST PREHEAT
50
0
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
TIME (MINUTES)
FIGURE 15. WAVE SOLDER PROFILE
250
MAXIMUM
TEMPERATURE 222oC
200
40-80
SECONDS
ABOVE 183 oC
150
RAMP RATE
>50oC /s
100
PREHEAT ZONE
50
0
0.0 0.5
1.0
1.5
2.0
2.5
3.0
3.5
TIME (MINUTES)
FIGURE 16. VAPOR PHASE SOLDER PROFILE
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