Hi again!

Thank you all for the responses to my question about the MOLE matter.
Here's some of the answers:

>Preheat temperature should be measured in a bare area of the pwb
laminate
(without traces or ground planes) and preferably near the geometric
center
of the pwb upper surface.  A thermocouple should be attached to the
surface
of the pwb using a thermally conductive adhesive or epoxy.

>The thermocouples should be located in the hole itself.  I would put
one on
the top (non wave side) to be on the safe side, but this is not
necessary
unless there is a problem with the post waved boards

>Topside PCB temp (in open area)
Bottomside PCB temp (in open area) thru a via or non plated hole

>start with three probes: one on a top side termination, one on a bottom

termination and one on a component lead that best represents the
component set

As you can see, i got many different answers, almost all seemed to agree
that the thermocouples (or probes) should be placed on top (in open
area, non solder side) and inside a PTH.
But then i also got some answers recommending me to place the
thermocouples bottomside of the PCB.
To place thermocouple on the bottomside feels like measuring if the wave
solderings preheating system are ok and nothing relating to the PCB.
What kind of information can you read out from the bottomside of the
PCB?
Is it important to put the thermocouples inside a PTH?
Can it cause different temperature read outs due to the placement of the
the thermocouple in height for example in a thick 8 layer board?

Thanks,
Jan Merstrand
Ericsson Microwave System AB