ERT-J1VS104FA Datasheet, PDF (13/14 Pages) Panasonic Semiconductor – The NTC Thermistors

4. Soldering
4.1 Reflow Soldering
The reflow soldering temperature conditions are
each temperature curves of Preheating, Temp. rise,
Heating, Peak and Gradual cooling. Large temperature
difference caused by rapid heat application to the
Thermistors may lead to excessive thermal stresses,
contributing to the thermal cracks. The Preheating
temperature requires controlling with great care so
that tombstone phenomenon may be prevented.
Item
1Preheating
2Temp. rise
3Heating
4Peak
5Gradual cooling
Temperature
140 to 180 °C
Preheating temp
to Peak temp.
220 °C min.
260 °C max.
Peak temp.
to 140 °C
Period or Speed
60 to 120 sec
2 to 5 °C /sec
60 sec max.
10 sec max.
1 to 4 °C /sec
Recommended profile of Reflow soldering (EX)
4 Peak
260
220
2 Temp. rise
5 Gradual
180
cooling
140
1 Preheating 3 Heating
Time
60 to 120 sec 60 sec max.
△T : Allowable temperature difference △T < 150 °C
The rapid cooling (forced cooling) during Gradual
cooling part should be avoided, because this may
cause defects such as the thermal cracks, etc.
When the Thermistors are immersed into a cleaning
solvent, make sure that the surface temperatures of
the devices do not exceed 100 °C.
Performing reflow soldering twice under the conditions
shown in the figure above [Recommended profile of
Reflow soldering (EX)] will not cause any problems.
However, pay attention to the possible warp and
bending of the PC board.
4.2 Hand Soldering
Hand soldering typically causes significant temperature
change, which may induce excessive thermal stresses
inside the Thermitors, resulting in the thermal cracks, etc.
In order to prevent any defects, the following should be
observed.
·The temperature of the soldering tips should be
controlled with special care.
·The direct contact of soldering tips with the
Thermistors and/or terminal electrodes should be
avoided.
·Dismounted Thermistors shall not be reused.
(1) Condition 1 (with preheating)
(a) Soldering:
f1.0 mm or below Thread eutectic solder with
soldering flux^✽ in the core.
✽ Rosin-based and non-activated flux is
recommended.
Multilayer NTC Thermistors
(b) Preheating:
The Thermistors shall be preheated so that the
“Temperature Gradient” between the devices
and the tip of soldering iron is 150 °C or below.
(c) Temperature of Iron tip: 300 °C max.
(The required amount of solder shall be
melted in advance on the soldering tip.)
(d) Gradual cooling:
After soldering, the Thermistors shall be
cooled gradually at room temperature.
Recommended profile of Hand soldering (EX)
Gradual cooling
Preheating
60 to 120 sec
3 sec max.
△T : Allowable temperature difference △T < 150 °C
(2) Condition 2 (without preheating)
Hand soldering can be performed without
preheating, by following the conditions below:
(a) Soldering iron tip shall never directly touch
the ceramic and terminal electrodes of the
Thermistors.
(b) The lands are sufficiently preheated with a
soldering iron tip before sliding the soldering
iron tip to the terminal electrodes of the
Thermistors for soldering.
Conditions of Hand soldering without preheating
Item
Condition
Temperature of Iron tip
270 °C max.
Wattage
20 W max.
Shape of Iron tip
f3 mm max.
Soldering time with
a soldering iron
3 sec max.
5. Post Soldering Cleaning
5.1 Cleaning solvent
Soldering flux residue may remain on the PC board
if cleaned with an inappropriate solvent. This may
deteriorate the electrical characteristics and reliability
of the Thermistors.
5.2 Cleaning conditions
Inappropriate cleaning conditions such as insufficient
cleaning or excessive cleaning may impair the electrical
characteristics and reliability of the Thermistors.
(1) Insufficient cleaning can lead to:
(a) The halogen substance found in the residue
of the soldering flux may cause the metal of
terminal electrodes to corrode.
(b) The halogen substance found in the residue
of the soldering flux on the surface of the
Thermistors may change resistance values.
(c) Water-soluble soldering flux may have more
remarkable tendencies of (a) and (b) above
compared to those of rosin soldering flux.
00 Sep. 2010