01870194| Datasheet

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Mounting Instructions Mounting instructions
1 1.1 Soldering Leaded NTC thermistors

Leaded thermistors comply with the solderability requirements specified by CECC. When soldering, care must be taken that the NTC thermistors are not damaged by excessive heat. The following maximum temperatures, maximum time spans and minimum distances have to be observed: Dip soldering Bath temperature Soldering time Distance from thermistor max. 260 C max. 4 s min. 6 mm Iron soldering max. 360 C max. 2 s min. 6 mm

Under more severe soldering conditions the resistance may change. 1.2 Leadless NTC thermistors

In case of NTC thermistors without leads, soldering is restricted to devices which are provided with a solderable metallization. The temperature shock caused by the application of hot solder may produce fine cracks in the ceramic, resulting in changes in resistance. To prevent leaching of the metallization, solder with silver additives or with a low tin content should be used. In addition, soldering methods should be employed which permit short soldering times. 1.3 SMD NTC thermistors

SMD NTC thermistors can be provided with a nickel barrier termination or with silver-palladium termination. The usage of mild, non-activated fluxes for soldering is recommended as well as a proper cleaning of the PCB.
I Nickel barrier termination

The nickel barrier layer of the silver/nickel/tin termination (see figure 1) prevents leaching of the silver base metalization layer. This allows great flexibility in the selection of soldering parameters. The tin prevents the nickel layer from oxidizing and thus ensures better wetting by the solder. The nickel barrier termination is suitable for all commonly-used soldering methods.

Tin [Sn] Nickel [Ni] Silver [Ag]
VAR0381-W

Figure 1

SMD NTC thermistors, structure of nickel barrier termination

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