Pressure on i.MX8M BGA

[davood]

On i.MX8M chip, if a heat-sink is not used, but instead the chip is pressed on by the cast housing for heat transfer, what is the maximum pressure that can be applied on the chip before it becomes a concern for the BGA?  Does the existing eval board designed the spring loaded heat-sink with that pressure in mind?   Where will this force or the pressure can be found?

[gusarambula]

Hello Davood Motlagh,

Please look at Application Note 4871 (link below) for reference.

https://www.nxp.com/docs/en/application-note/AN4871.pdf

While the 17X17mm bare die package of the i.MX8M is not specifically shown on this document, the values are based on a formula having the BGA pad and PCB pad size as inputs. The maximum force for the 17X17mm i.MX8M would also be 10lb and it must be applied parallel to the cast housing similar to what is shown in figure 5 of the application note. There must also be a thermal interface material as this protects the package from direct contact with the housing or heatsink.

I hope this helps!
Regards,