4 BFR Estimation Techniques

Various techniques exist for estimating BFR: experimental, derived from field observations of incidents and customer returns/field failures, or an estimation based on industry-accepted reliability guides coupled with some engineering judgment.

Here are a few examples of empirical techniques; however, these only account for intrinsic (silicon) failures and disregard the contribution from silicon and package interactions:

• Temperature bias operating life test
• High-temperature operating life test
• Extended life reliability test

Field observations, conversely, require accurate and extensive record keeping, and this is not available when a new product is introduced to market. Additionally, many semiconductor manufacturers do not receive all of the customer returns, making it impossible to meet the requirement for accurate and extensive records to estimate BFR.

The following industry reliability guides can provide a estimation for functional safety analysis:

• IEC technical report (TR) 62380⁽³⁾ and IEC 61709⁽⁵⁾
• SN 29500, the Siemens AG standard for the reliability prediction of electronic and electromechanical components
• FIDES such as a military handbook or other documentation from a credible source

The remainder of this paper focuses on the use of IEC TR 62380 and SN 29500 to estimate BFR.