[time-nuts] What do people use for measuring temperature?

[Richard (Rick) Karlquist]

On 9/29/2020 4:38 PM, Bob kb8tq wrote:
> Hi
> 
> The gotcha with *any* SMT part is that stress / strain from the soldering process gets into the
> performance of the part for a *long* time. There is no mechanical “buffering” in most parts. Whatever
> the PCB does is what the guts of the part sees ….
> 
> Given the popularity here on the list of hand soldering SMT parts, that’s a very high stress way to
> mount them …. yikes ….
> 
> Bob
> 

The other issue with SMT thermistors is that you normally
want glass bead thermistors with very long and very
skinny leads that reduce head transmission via the leads.
Proper management of the thermistor leads in OCXO's
is very important.  In the 10811 for example, the
thermistor in potted into a very deep hole using
thermally conductive (silver loaded) epoxy.  The
leads run all the way through this hole which
is filled with the epoxy.  The hole is drilled in
the oven mass.  An analogous scheme is used in
the E1983A.

What you could do with SMT thermistors is to glue
leads onto them with *electrically* conductive epoxy.
This avoids soldering trauma.
You could use very small gauge wire, as is SOP with
leaded thermistors.  You might take the opportunity
to use wire with low thermal conductivity, such as
nickel.

Rick N6RK