Measuring Warpage & Analysis Objectives

Measuring warpage requires an understanding of how warpage is defined in the context of the project.

To properly interpret the deflection results, you must consider:

• How warpage is defined.
• How the part is going to be used.
• How the part is assembled with other components.

Some parts may have an assembly surface, or sealing surface that must be flat within some tolerance. Other parts have many assembly features like snap fits or screw bosses that must fit to other parts. Most parts have multiple dimensions or geometric tolerances that must be met. You must understand how warpage is defined so you can correctly setup the deflection plots using anchors or local coordinate systems (LCS).

Another aspect of reviewing deflection results is how multiple studies are compared. Comparing deflection results between studies may be different from looking at a particular warpage tolerance. When comparing results between studies, normally the objective is to compare changes between studies more than comparing each study to the warpage tolerance. It is usually much easier to look at deflections to compare differences between studies, than it is to compare deflections to a tolerance.

Note: The method used to look at deflection plots is most critical when the deflection is close to a tolerance.

If the flatness plane is the XY plane with a 1.0-mm tolerance, then Z-deflection represents the flatness. If the entire Z-deflection is under 1.0 mm, then the plane of interest is within tolerance. If the Z-deflection for the total part is 10 mm, for example, then the plane of interest, is likely to be out of tolerance. When the plane of interest has a deflection about equal to its tolerance, then the exact method of looking at the results is critical.