METHOD TO MEASURE THERMAL IMPEDANCE OF LIGHT DIODES Russian patent published in 2015 - IPC G01R31/00 

FIELD: measurement equipment.

SUBSTANCE: invention relates to technology for measurement of thermal parameters of semiconductor items and may be used for outgoing and incoming inspection of light guides manufacturing quality. The method consists in the fact that a sequence of pulses of heating current with constant amplitude that is width-pulse modulated according to the harmonic law with modulation depth a is sent via the light diode, and in the gaps between pulses of heating current they send heating current via the light diode, following the results of voltage measurement on the light diode during action of heating current pulses and in intervals between them they determine amplitude of the first harmonics with the capacity P_m1(Ω), consumed by the light diode, and amplitude of the first harmonics of the temperature sensitive parameter $${\tilde{U}}_{ml}^{TP}\left(\Omega \right)$$ with available negative temperature coefficient K_T - direct voltage at p-n transition of the light diode as initial current flows through it and phase is shifted between them φ(Ω) at the frequency of modulation of heating capacity, they measure average capacity $${\overline{W}}_{opt}$$ of optical radiation of the light diode for the time of heating, and the module of thermal impedance is found according to the formula $$\left|Z_T\left(\Omega \right)\right|=\frac{{\tilde{U}}_{ml}^{TP}\left(\Omega \right)}{K_T\left(P_{ml}\left(\Omega \right)-a{\overline{W}}_{opt}\right)},$$ and phase φ_T(Ω_M) of thermal impedance of the light diode is equal to the difference of phases shifted by 180° between the first harmonics of the temperature sensitive parameter and the first harmonics of capacity.

EFFECT: increased accuracy of measurement of module of thermal impedance of light diodes.

2 dwg