Embedded RF Test Circuitry for Ball Bond Failure Detection

The patent implements preliminary detection of ball bond integrity by measuring impedance characteristics before the bonds fail completely. The test circuitry continuously monitors the electrical properties of the ball bonds, enabling early detection of degradation caused by mechanical strain and thermal expansion, allowing preventive action before catastrophic failure occurs.

The patent changes the measurement parameter from DC resistance to RF impedance characteristics. By using AC signals at radio frequencies and measuring the complex impedance (including reactive components), the system can detect ball bond failures more accurately. The test circuitry applies RF signals and measures the resulting impedance, which changes characteristically when ball bonds fail, while DC resistance variations do not affect the RF measurement results.

The patent introduces directional couplers as intermediary components between the power amplifier output paths and the power detectors. These directional couplers are designed to pass signals in one direction while blocking signals in the opposite direction. By placing directional couplers in the signal path, the system can accurately measure forward power without contamination from reflected power or signals traveling in the opposite direction, thus preserving signal direction information.

The patent implements a feedback mechanism where the test circuitry continuously monitors ball bond impedance characteristics and provides feedback about their condition. The system measures the electrical properties of the ball bonds at regular intervals, compares them against baseline values, and detects changes indicating degradation from thermal cycling. This feedback enables continuous assessment of ball bond health throughout the operational lifetime, allowing the system to track cumulative thermal stress effects and predict potential failures before they occur.