ERT-J1VA220J Datasheet, PDF (11/14 Pages) Panasonic Semiconductor – The NTC Thermistors

1.3 Environmental Restrictions
The Thermistors shall not be operated and/or stored
under the following conditions.
(1) Environmental conditions
(a) Under direct exposure to water or salt water
(b) Under conditions where water can condense
and/or dew can form
(c) Under conditions containing corrosive gases
such as hydrogen sulfide, sulfurous acid,
chlorine and ammonia
(2) Mechanical conditions
Under severe conditions of vibration or impact
beyond the specified conditions found in the
Specifi cations.
1.4 Measurement of Resistance
The resistance of the Thermistors varies dependent
on ambient temperatures and self-heating. Note the
following points when measuring resistance values of
the Thermistors during inspection or when considering
them for circuits.
1 Measurement temp : 25±0.1 °C
Measurement in liquid (silicon oil, etc.) is
recommended for a stable measurement temperature.
2 Power : 0.10 mW max.
4 terminal measurement with a constant-current
power supply is recommended.
2. Design of Printed Circuit Board
2.1 Selection of Printed Circuit Boards
When the Thermistors are mounted and soldered on
an “Alumina Substrate”, the substrate influences the
Thermistors’ reliability against “Temperature Cycles”
and “Heat shock” due to the difference in the thermal
expansion coefficient between them. Confirm that
the actual board used does not deteriorate the
characteristics of the Thermistors.
2.2 Design of Land Pattern
(1) Recommended land dimensions are shown below.
Use the proper amount of solder in order to prevent
cracking. Using too much solder places excessive
stress on the Thermistors.
Recommended Land Dimensions
Land
SMD
Solder resist
b
a
Size Code
(EIA)
Z(0201)
0(0402)
1(0603)
Component
dimensions
LWT
0.6 0.3 0.3
1.0 0.5 0.5
1.6 0.8 0.8
Unit (mm)
a
b
c
0.2 to 0.3 0.25 to 0.30 0.2 to 0.3
0.4 to 0.5 0.4 to 0.5 0.4 to 0.5
0.8 to 1.0 0.6 to 0.8 0.6 to 0.8
Multilayer NTC Thermistors
(2) The size of lands shall be designed to have
equal spacing between the right and left sides. If
the amount of solder on the right land is different
from that on the left land, the component may
be cracked by stress since the side with a larger
amount of solder solidifies later during cooling.
Recommended Amount of Solder
(a) Excessive amount (b) Proper amount (c) Insufficient amount
2.3 Utilization of Solder Resist
(1) Solder resist shall be utilized to equalize the
amounts of solder on both sides.
(2) Solder resist shall be used to divide the pattern
for the following cases;
·Components are arranged closely.
·The Thermistor is mounted near a component
with lead wires.
·The Thermistor is placed near a chassis.
See the table below.
Prohibited Applications and Recommended Applications
Item
Prohibited
applications
Improved applications
by pattern division
Mixed mounting
with a component
with lead wires
The lead wire of a
component with lead wires
Solder resist
Arrangement near
chassis
Chassis
Solder
(Ground solder)
Retro-fitting of
component with
lead wires
Electrode pattern
A lead wire of
Soldering Retro-fitted
iron
component
Solder resist
Solder resist
Lateral
arrangement
Portion to be
excessively soldered
Land
Solder resist
2.4 Component Layout
The Thermistors/components shall be placed on the
PC board such that both electrodes are subjected
to uniform stresses, or to position the component
electrodes at right angles to the grid glove or
bending line. This should be done to avoid
cracking the Thermistors from bending the PC
board after or during placing/mounting on the PC
board. Placement of the Thermistors near heating
elements also requires that great care be taken
in order to avoid stresses from rapid heating and
cooling.
00 Sep. 2010