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We are seeking guidance regarding the thermal exposure limits of your NTC thermistor part number TX04F103F3435ER.
In our manufacturing process, the thermistors are assembled onto a PCBA and then exposed, unpowered, to an oven process at 150°C for approximately 4 hours 15 minutes. This exposure occurs after SMT assembly/reflow and is part of a subsequent curing process. The thermistors are not electrically powered during this exposure.
The datasheet lists the operating temperature range as -40°C to +125°C. We understand this to be the range over which the thermistor is specified to operate within its published electrical characteristics. However, our concern is whether an unpowered process/storage exposure at 150°C for several hours could affect the thermistor’s performance or reliability.
Could you please advise on the following:
Is 150°C for approximately 4.25 hours acceptable for this part as a one-time or repeated process exposure?
Would this exposure be expected to cause any permanent resistance drift, B-value shift, calibration change, or long-term reliability concern?
Are there specific versions of this thermistor series that are rated or suitable for 150°C exposure?
Are there any recommended post-exposure checks, derating guidance, or maximum allowable time-at-temperature limits for this part?
Would this process exposure affect the warranty, qualification, or compliance of the component?
Hello dario1,
Welcome to the DigiKey TechForum.
With an operating temperature up to +125°C, that is what we have to go on, for what it can handle, unless there are other stipulations on the datasheet.
The datasheet does say “Some parts can resist in operating temperature range up to 150°C”, but it does not specify which ones.
I think PaulHutch had the best idea, and that was to contact the manufacturer on this.
They should know if it can handle that temperature and time frame, as they have done all their testing and qualifications on the parts, and would be the best source for this information, because it is outside the normal operation range.
As Paul suggests, the product manufacturer is best positioned to offer advice in relation to such questions.
One may observe that many chemical and adjacent processes that contribute to parameter shifts and such can be described by the Arrhenius equation, which in rule-of-thumb form suggests a doubling of rate for every 10°C increase in temperature. That, in consideration with the suggested soldering profiles may offer some insights on such things.
Regardless, component manufacturers’ responsibilities and warranties generally end with the delivery of product that conforms to the published specifications. You’re responsible for any additional processing that you subject them to, and deciding whether or not the result is suitable for the purposes you intend.
