You make an excellent point, Rich. When I have a marginal temperature indicated on a component, relative to the MOT of the supporting PWB, I will add a thermocouple(s) to the PWB surface at the closest "insulated" point near the solder pad(s) for that component, to round out the data. Generally, though the design parameters of products vary widely, there is some heat sinking effects from both the component leads (radiating and convecting heat into the local environment) and in the PWB's copper. Indeed, a component's body temperature can well exceed the MOT of the supporting PWB, while the PWB temperature can run well below the MOT, particularly if there's a significant ground plane involved.
Regards, Peter L. Tarver, PE [email protected] -----Original Message----- From: Rich Nute [mailto:[email protected]] Sent: Wednesday, October 11, 2000 12:02 AM Typically, temperature measurements are made on the component, not on the board. This is a worst- case temperature that assumes no temperature drop between the component (along its copper leads) and the board conductor. Best regards, Rich
