I'm trying to find a quick & dirty method of determining tightening torque values for electronic packaging applications.

In other words, a torque guide for the following screw sizes and screw types:

Screw Sizes:   #2-#6,  M2-M6
Screw Types:  steel, aluminum, plastic
Screwed Into:  threaded hole made of steel, aluminum, or plastic

I realize I need to know the bolt tensio desired, but does someone know the accepted industry practice for electronic packaging??

Thank you,

CHRIS