FIDES 2009 guide, in the Hybrid section, Lambda Connections (page 175)
There is a factor Delta CTE and a table with values. This table has caused us some confusion.
For example if I have a PCB without Cu/In/Cu and a case that is Ceramic then Delta CTE = 8 * 10e-6 / C
Am I just supposed to use the 8 * 10e-6 value as the CTE or do I need to do something with the temperature?
I wasn′t sure if value was meant to be ′per degrees C′ or ′divided by the ambient temperature′
Thanks
Alyn
There is a factor Delta CTE and a table with values. This table has caused us some confusion.
For example if I have a PCB without Cu/In/Cu and a case that is Ceramic then Delta CTE = 8 * 10e-6 / C
Am I just supposed to use the 8 * 10e-6 value as the CTE or do I need to do something with the temperature?
I wasn′t sure if value was meant to be ′per degrees C′ or ′divided by the ambient temperature′
Thanks
Alyn
Dear,
The calculation of the Lambda0_TCY ask for the Delta_CTE. You found the right Delta_CTE in the table at the bottom of the page 175.
You now just have to use this value in the calculation of Lambda0_TCY as defined at the top of the page 175. You also need the distance D between the furthest connections of the module and the K factor which is also defined page 175. You don′t need temperature at this step of the calculation.
We have found some cases where the K value becommes negative. In this case, take Lambda0_TCY = 0. It means that connections are very supple and therefore themal cycling doesnt generates strain.
All the best with FIDES!
Lambda