BATH TUB CURVE

                      Bath tub curve 

The general failure curve for commonly used electronic components is known as the bath tub curve due to its shape. It is generally the variation of failure rate of component with time. it can be considered as a summa-tion of three processes - An early failure pro-cess, A random failure process and A wear- out process.

During the initial stage of the product when it is new, it is more likely to fail. This period is termed as break-in period and failures are termed as infant or early failure. This high failure rate is due to design errors, manufacturing, defects or installation defects. This is the period of severe failure and debugging of these failure. These early failure can be minimized by improving production quality control , subjecting the parts to a proof test before they are" running in".

After passing through initial break-in period, failure occurs less frequently and eventually the failure rate reaches a constant value. The failure in this period are termed as service failure. These failure occurs randomly and do not follow any predictable pattern. The reason behind these failures are the random overloads or random flaws.

Finally, after a long time the material and the components began to deteriorated, as they have exceeded their service life. During this stage failure rate again accelerates and failures in this stage are appropriately term as wear-out failures.