JPS645263B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to a life testing method for a non-linear resistor etc. whose main component is Z _o O. The conventional life test method is an accelerated test method in which power is actually applied for a certain period of time under harsher temperatures and voltages than the actual usage conditions, and the lifespan under the actual usage conditions is estimated from the degree of deterioration due to the actual power application. It was hot. Therefore, the resistor element subjected to the test was a destructive test in which deterioration was inevitable, and there was a drawback that the lifespan could only be evaluated by sampling. In addition, because the test is conducted under harsh conditions, the amount of heat generated by the resistor element itself is high due to the resistor element current, and it is difficult to match the temperature conditions of the element itself even in a constant temperature atmosphere. It was difficult to evaluate the lifespan of the SUMMARY OF THE INVENTION An object of the present invention is to provide a test method that enables an accurate and short-term non-destructive life test by evaluating the life characteristics and deterioration state of a non-linear resistor from its dielectric properties. FIG. 1 shows a measuring device used in the test method of the present invention. Reference numeral 2 denotes an oscillation device, and the oscillation device 2 includes a variable voltage, variable frequency AC power supply section 3 and a bridge element section 7 for measuring dielectric characteristics. Reference numeral 4 denotes a sample product, which is configured so that a DC voltage from a DC power supply 1 and an AC voltage from an oscillation device 2 are applied simultaneously, and the DC current from the DC power supply 1 is read by an ammeter 5. Further, in the sample 4, a circuit for applying a voltage to the sample 4 is configured through the instantaneous charging current suppressing resistor 6. The capacitor 8 is for cutting off the DC component flowing into the oscillator 2. The sample 4 is placed in an atmosphere whose temperature can be controlled, such as in a constant temperature layer. For example, by connecting to such a measuring device,
First, as shown in Fig. 2, the sample 4, which has been controlled to an arbitrary measurement temperature of 200°C, is supplied with a DC power supply 1, for example, from the counter electrode 4A to the main electrode 4B of the sample 4.
A DC voltage of 500 V/mm or less is applied, and it is determined from the change in the ammeter 5 that the current has reached an equilibrium state (steady leakage current). After reaching an equilibrium state, an AC voltage of several V/mm within, for example, 10 ^-1 to 10 ⁶ Hz is applied from the oscillator 2 side, and the dielectric properties (capacitance C, dielectric loss tangent tan δ, etc.) of the sample 4 are measured. The electric field dependence and frequency dependence of are measured, and the life of sample 4 is evaluated from the measurement results. In this evaluation, life is predicted from the amount of change in capacitance C or dielectric loss tangent tan δ of the element with respect to changes in applied voltage. As an example in which life can be evaluated by this test method, the capacitance characteristics of four elements A, B, C, and D shown in the table below are shown in FIG. 3, and the dielectric loss tangent characteristics are shown in FIG. 4. In the table, the predicted lifetimes of elements A, B, C,
This is a predicted life time obtained by performing a conventional accelerated test on an element with the same lot number as D, and shows that the magnitude of the life between each element is A<B<C<<D. The capacitance change characteristics C/C _p of these elements A, B, C, and D are shown in Figure 3. The shorter the life of the element, the less stable it is to voltage application, and the capacitance change characteristics C/C p of these elements A, B, C, and D are shown in Figure 3. begins to increase. This tendency becomes remarkable under high temperature and low frequency conditions. Note that C _p is the capacitance when no voltage is applied. Similarly, the dielectric loss tangent of elements A, B, C, and D
As shown in FIG. 4, the change characteristics of tan δ are such that the longer the life, the smaller the amount of change, and the increase starts at a higher voltage. Note that tan δ _p is the dielectric loss tangent when no voltage is applied.

[Table] Therefore, by measuring the capacitance change or dielectric loss tangent change characteristics with respect to changes in the voltage applied to the element, it is possible to determine whether or not the life of the element is good or bad. This evaluation method allows measurement at a set temperature without destroying or deteriorating the device, and without considering the temperature rise of the device due to an increase in current. In this life evaluation based on dielectric properties, in order to accurately evaluate the superiority or inferiority of multiple elements that have been determined to have similar lifespans, it is possible to measure the dielectric properties after an extremely short DC application test. Figure 5a shows two types of element characteristics E and F, which were determined to have similar lifetimes from the voltage-capacitance characteristics before the life test was applied, and these two types of elements were subjected to a short-time test. Later voltage -
There is a large difference in capacitance characteristics between the elements as shown in FIG. This also appears in the difference in frequency-dissipation factor characteristics shown in FIG. 5c, and means that accurate life evaluation of elements E and F can be performed. Note that the voltage-current characteristics obtained by the conventional evaluation method before and after the same direct current application test performed to obtain the above evaluation show no significant difference between elements E and F, as shown in FIG. 5d. Therefore, for devices whose lifetime is difficult to determine based on their initial dielectric properties, it can be easily determined by measuring their dielectric properties after conducting a short-time direct current application test.
This means that minute deterioration that cannot be measured from conventional voltage-current characteristics can be measured from dielectric characteristics using the method of the present invention. As described above, the life test method according to the present invention is
In order to obtain predicted element life from changes in dielectric properties,
It becomes possible to evaluate the life of the element in a short period of time without subjecting it to accelerated testing, and it becomes possible to measure even minute deterioration of the element.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a test device used in the life test method of the present invention, Fig. 2 is a cross-sectional view of a nonlinear resistor, and Figs. It is a characteristic diagram. 1... DC power supply, 2... Oscillator, 4... Sample, 5... Ammeter.

Claims (1)

[Scope of Claims] 1. A lifespan test method, characterized in that the lifespan of a non-linear resistor is determined from changes in dielectric properties of the resistor in response to changes in DC voltage applied to the non-linear resistor. 2. A lifespan test method according to claim 1, in which the lifespan is determined from the voltage-dielectric characteristics of a non-linear resistor after applying a DC voltage between the electrodes of the resistor for a short time.