To Edit Tolerance Stackups

Edit the Stackup

After you create the stackup, you can modify the following options in the stackup definition. Click the < and > symbols in the table to navigate between the Stackup Details and Summary table display.

• Click the stackup name in the Summary table to rename the stackup.
• Change the numerical requirements. By default, Tolerance Analysis assumes that each stackup must be >=0 because most tolerance stackup analyses are performed to make sure that there is enough clearance for the parts to fit together. However, you can click > in the Summary table and change to any of the following definition types:
  • Symmetric
  • Plus Minus
  • Limits
  • Upper Limit
  • Lower Limit
• Change the analysis type by selecting the drop-down arrow to the right of Objective. The options include:
  • Worst Case
  • RSS (Root Sum Squared)
  • Statistical. The advantage of Statistical over RSS is that you can define the target quality level for the stackup regardless of what has been assumed for the part dimensions in the Settings dialog box. Supported options include:
    • Cpk
    • Σ (Sigma), not to be confused with lower case σ often representing the standard deviation of a normal distribution.
    • % Yield
    • DPMO (Defects per Million Opportunities)

When you edit a tolerance stackup. the calculated results at the bottom of the table and in the Results graph update automatically.