CN104392073A - Electronic product reliability accelerated test method based on failure physics - Google Patents

Abstract

The invention belongs to an electronic product reliability technology and relates to an electronic product reliability accelerated test method based on failure physics. The electronic product reliability accelerated test method is characterized by comprising the following steps: building a digital prototype model of an electronic product; analyzing a thermal stress state and a vibration stress state; determining a failure mechanism of the electronic product; determining a failure physics model of the electronic product; providing temperature conditions for reliability accelerated test; calculating accelerated test time; calculating the vibration conditions of the reliability accelerated test; evaluating test implementation and test results. The electronic product reliability accelerated test method provided by the invention has the benefits that the transfer effect of stress in a product structure can be considered, the accuracy of the model is improved, and further, the test result accuracy is improved.

Description

A kind of electronic product reliability accelerated test method based on faulty physical

Technical field

The invention belongs to electronic product reliability experimental technique, relate to a kind of electronic product reliability accelerated test method based on faulty physical.

Background technology

Modern high new equipment is high to reliability level requirement, and the products such as the electronics/electromechanics/photoelectricity wherein played a crucial role are to digitizing, miniaturization, densification, multifunction and complicated future development, and its reliability requirement is also higher.The requirement that the reliability index mean time between failures (MTBF) of many products has reaches thousands of hours, even reach up to ten thousand hours, experimental technique is traditionally tested, test period at least should be the required value of 1.1 times, needs several months even a few year just can complete test like this when dropping into test battery exemplar; And if exemplar tested by the many covers of input, then the expense of exemplar is difficult to bear equally.Therefore, in the face of the development feature that the high reliability equipment preparation cycle is short, research fund is high, the existing convectional reliability statistical test method based on environmental simulation and assessment technology can not meet product development requirement because required time is long, funds are high, and the reliability accelerating experiment technology adopt and strengthen proof stress, shortening test period has become the inexorable trend of reliability compliance test technical development.Existing electronic product reliability accelerated test method is nearly all based upon on experiential basis, applies what stress to product, depends on the understanding to product dominant failure mechanism.Accelerated test model conventional at present comprises the Arrhenius relationship relevant with temperature, Ai Lin model, the inverse power law model that description thermal stress and mechanical stress are accelerated, the two stress resultant acceleration model of temperature-humidity, Generalized Logarithmic-linear model that many stress accelerates simultaneously, progressive damage exponential model etc.But due to the statistics acceleration model that these models are all based on components and parts failure mechanism, this acceleration model can not consider the transmission effect of stress in product structure, and the accuracy of model is relatively low, causes the error of test findings large.

Summary of the invention

The object of the invention is: propose a kind of electronic product reliability accelerated test method based on faulty physical, to consider the transmission effect of stress in product structure, improve the accuracy of model, and then improve stringency of test.

Technical scheme of the present invention is: a kind of electronic product reliability accelerated test method based on faulty physical, is characterized in that: the step of carrying out electronic product reliability accelerated test is as follows:

1, the digital prototype model of electronic product is built: digital prototype model refers to two-dimensional digital PM prototype model or 3-dimensional digital PM prototype model, and electronic product comprises cabinet, support, module, circuit board and components and parts;

2, thermal stress state and vibration stress state analysis: adopt the thermal stress state of finite simulation element analysis software analytical electron product under load-up condition and vibration stress state, load-up condition refers to environmental load and operating load;

3, the failure mechanism of electronic product is determined: according to thermal stress state that electronic product bears and vibration stress state, in conjunction with the fault mode of electronic product, impact and HAZAN report, outfield and laboratory fault data, determine the dominant failure position of electronic product, failed module, disable system plate and incipient fault components and parts, and failure mechanism.

4, the physics model of failure of electronic product is determined: according to the failure mechanism of incipient fault components and parts, determine the physics model of failure of electronic product, the model parameters such as the geometrical structure parameter of incipient fault components and parts, material properties, stress parameters, the Modifying model factor are set;

5, the temperature conditions of given reliability accelerated test: high temperature: the upper limit of the temperature range limit provided by test electron product deducts 10 DEG C ~ 20 DEG C, and the duration is that temperature stabilization times adds by the test electron product test time; Low temperature: the lower limit of the temperature range limit provided by test electron product adds 5 DEG C ~ 10 DEG C, and the duration is that temperature stabilization times adds by the test electron product test time; Rate of temperature change: 5 DEG C/min ~ 15 DEG C/min; :

6, accelerated test time T is calculated ₁: with by test electron product based on the temperature conditions in the reliability test sectional plane of environmental simulation and test period T ₀for input parameter, calculate the accelerated test time T under the temperature conditions provided in given reliability accelerated test ₁, concrete grammar is as follows:

6.1, accounting temperature condition speedup factor τ _v: according to the physics model of failure of electronic product, calculate the damage under the incipient fault components and parts temperature conditions in the reliability test sectional plane of environmental simulation, obtain n potential thin spot N of thermal fatigue failure under the temperature conditions continuous action in the reliability test sectional plane of environmental simulation ₁, N ₂..., N _n, starting fault cycles number of n potential thin spot is designated as N respectively _t1, N _t2... N _ti... N _tn, i=1,2 ... n; Calculate the damage at the temperature conditions of given reliability accelerated test, the starting fault cycles number obtaining n potential thin spot is designated as N' respectively _t1, N' _t2... N' _ti... N' _tn; The speedup factor τ of i-th trouble spot _vi:

${\mathrm{\τ}}_{\mathrm{Vi}}=\frac{N_{\mathrm{Ti}}}{{N^{\′}}_{\mathrm{Ti}}}\·\·\·\left[1\right]$

The speedup factor of n incipient fault point is carried out arithmetic mean, obtains product temperature speedup factor τ _v:

${\mathrm{\τ}}_V=\frac{1}{n}\underset{1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\τ}}_{\mathrm{Vi}}\·\·\·\left[2\right]$

6.2, accelerated test time T is calculated ₁:

$T_1=\frac{T_0}{{\mathrm{\τ}}_V\×t_1}\·\·\·\left[3\right]$

Wherein, t ₁for the temperature conditions time of given reliability accelerated test;

7, the vibration condition of reliability accelerated test is calculated: with the vibration condition of the reliability test sectional plane based on environmental simulation and corresponding vibration stress application time T ₀' be input parameter, calculate accelerated test time T ₁internal vibration stress application time T ₁' vibration value, concrete grammar is as follows:

7.1, vibration speedup factor b is calculated _v: according to the physics model of failure of electronic product, calculate the damage under the incipient fault components and parts vibration condition in the reliability test sectional plane of environmental simulation, obtain product vibration condition W in based on the reliability test sectional plane of environmental simulation _am the potential thin spot that lower vibrating fatigue lost efficacy, respectively at vibration condition W ₀₁with vibration condition W ₀₂under, the vibrating fatigue damage model drawn is the out-of-service time of counting yield when vibration durable trouble spot damage ratio is 1 respectively, by m potential thin spot at vibration condition W ₀₁under starting fault-time be designated as t _v1, t _v2..., t _vjt _vm, j=1,2 ... m; By m potential thin spot at vibration condition W ₀₂under starting fault-time be designated as t' _v1, t' _v2..., t' _vj,t' _vm, by a jth weak link point at vibration condition W ₀₁with vibration condition W ₀₂starting fault-time under condition substitutes into formula:

$\frac{{t_{\mathrm{vi}}}^{\′}}{t_{\mathrm{vi}}}={\left(\frac{W_{01}}{W_{02}}\right)}^{b_{\mathrm{vi}}}\·\·\·\left[4\right]$

Obtain the constant factor b of a jth trouble spot _vi; The speedup factor of m incipient fault point is carried out arithmetic mean, obtains vibrating speedup factor b _v:

$b_V=\frac{1}{m}\underset{1}{\overset{m}{\mathrm{\Σ}}}{b}_{\mathrm{vj}}\·\·\·\left[4\right]$

7.2, calculate at vibration stress application time T ₁' under vibration value W _b:

$W_b=W_a\×{\left(\frac{{T_0}^{\′}}{{T_1}^{\′}}\right)}^{\frac{1}{b_V}}\·\·\·\left[6\right]$

8, test is implemented and test findings assessment: integrated temperature and vibration stress condition, and carry out test according to the accelerated test condition after comprehensive, after off-test, according to the following formula to the one-sided confidence lower limit θ of mean time between failures MTBF under given degree of confidence of product _lassess:

${\mathrm{\θ}}_L\≥\frac{2T_0}{{\mathrm{\χ}}_{(1-c)(2r+2)}^2}\·\·\·\left[7\right]$

In formula: r is at reliability accelerated test time T ₁the chargeable fault number of interior appearance;

C is degree of confidence, C=0 ~ 1.

Advantage of the present invention is: propose a kind of electronic product reliability accelerated test method based on faulty physical, can consider the transmission effect of stress in product structure, improve the accuracy of model, and then improve stringency of test.

Accompanying drawing explanation

Fig. 1 is the reliability test sectional plane example based on environmental simulation, and in figure, the first half is temperature conditions, and horizontal ordinate is the time, and unit is min, and ordinate is temperature value, and unit is DEG C; In figure, the latter half is vibration condition, and horizontal ordinate is the time, and unit is min, and ordinate is vibration value, and represent with power spectrum density, unit is g ²/ Hz, corresponding diagram 2 vibrates the W in spectral pattern ₀value; Temperature conditions and vibration condition comprehensively apply, and only apply temperature conditions at 0th ~ 60min and 420min ~ 480min; 60min ~ 420min and 480min ~ 840min applies temperature and vibration condition simultaneously.

Fig. 2 is that the spectral pattern of vibration stress in Fig. 1 illustrates, horizontal ordinate is frequency, and unit is Hz, and ordinate is power spectrum density, and unit is g ²w in/Hz, figure ₀represent power spectrum metric.

Fig. 3 is the reliability accelerated test sectional illustrations calculated according to the method in the present invention, and in figure, the first half is temperature conditions, and horizontal ordinate is the time, and unit is min, and ordinate is temperature value, and unit is DEG C; In figure, the latter half is vibration condition, and horizontal ordinate is the time, and unit is min, and ordinate is vibration value, and represent with power spectrum density, unit is g ²/ Hz, corresponding diagram 2 vibrates the W in spectral pattern ₀value; Temperature conditions and vibration condition comprehensively apply, and only apply temperature conditions at 0th ~ 20min; 20min ~ 140min applies temperature and vibration condition simultaneously.

Embodiment

Below the present invention is described in further details.Based on an electronic product reliability accelerated test method for faulty physical, it is characterized in that: the step of carrying out electronic product reliability accelerated test is as follows:

1, the digital prototype model of electronic product is built: digital prototype model refers to two-dimensional digital PM prototype model or 3-dimensional digital PM prototype model, and electronic product comprises cabinet, support, module, circuit board and components and parts;

2, thermal stress state and vibration stress state analysis: adopt the thermal stress state of finite simulation element analysis software analytical electron product under load-up condition and vibration stress state, load-up condition refers to environmental load and operating load;

3, the failure mechanism of electronic product is determined: according to thermal stress state that electronic product bears and vibration stress state, in conjunction with the fault mode of electronic product, impact and HAZAN report, outfield and laboratory fault data, determine the dominant failure position of electronic product, failed module, disable system plate and incipient fault components and parts, and failure mechanism.

4, the physics model of failure of electronic product is determined: according to the failure mechanism of incipient fault components and parts, determine the physics model of failure of electronic product, the model parameters such as the geometrical structure parameter of incipient fault components and parts, material properties, stress parameters, the Modifying model factor are set;

5, the temperature conditions of given reliability accelerated test: high temperature: the upper limit of the temperature range limit provided by test electron product deducts 10 DEG C ~ 20 DEG C, and the duration is that temperature stabilization times adds by the test electron product test time; Low temperature: the lower limit of the temperature range limit provided by test electron product adds 5 DEG C ~ 10 DEG C, and the duration is that temperature stabilization times adds by the test electron product test time; Rate of temperature change: 5 DEG C/min ~ 15 DEG C/min; :

6, accelerated test time T is calculated ₁: with by test electron product based on the temperature conditions in the reliability test sectional plane of environmental simulation and test period T ₀for input parameter, calculate the accelerated test time T under the temperature conditions provided in given reliability accelerated test ₁, concrete grammar is as follows:

6.1, accounting temperature condition speedup factor τ _v: according to the physics model of failure of electronic product, calculate the damage under the incipient fault components and parts temperature conditions in the reliability test sectional plane of environmental simulation, obtain n potential thin spot N of thermal fatigue failure under the temperature conditions continuous action in the reliability test sectional plane of environmental simulation ₁, N ₂..., N _n, starting fault cycles number of n potential thin spot is designated as N respectively _t1, N _t2... N _ti... N _tn, i=1,2 ... n; Calculate the damage at the temperature conditions of given reliability accelerated test, the starting fault cycles number obtaining n potential thin spot is designated as N' respectively _t1, N' _t2... N' _ti... N' _tn; The speedup factor τ of i-th trouble spot _vi:

${\mathrm{\τ}}_{\mathrm{Vi}}=\frac{N_{\mathrm{Ti}}}{{N^{\′}}_{\mathrm{Ti}}}\·\·\·\left[8\right]$

The speedup factor of n incipient fault point is carried out arithmetic mean, obtains product temperature speedup factor τ _v:

${\mathrm{\τ}}_V=\frac{1}{n}\underset{1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\τ}}_{\mathrm{Vi}}\·\·\·\left[9\right]$

6.2, accelerated test time T is calculated ₁:

$T_1=\frac{T_0}{{\mathrm{\τ}}_V\×t_1}\·\·\·\left[10\right]$

Wherein, t ₁for the temperature conditions time of given reliability accelerated test;

7, the vibration condition of reliability accelerated test is calculated: with the vibration condition of the reliability test sectional plane based on environmental simulation and corresponding vibration stress application time T ₀' be input parameter, calculate accelerated test time T ₁internal vibration stress application time T ₁' vibration value, concrete grammar is as follows:

7.1, vibration speedup factor b is calculated _v: according to the physics model of failure of electronic product, calculate the damage under the incipient fault components and parts vibration condition in the reliability test sectional plane of environmental simulation, obtain product vibration condition W in based on the reliability test sectional plane of environmental simulation _am the potential thin spot that lower vibrating fatigue lost efficacy, respectively at vibration condition W ₀₁with vibration condition W ₀₂under, the vibrating fatigue damage model drawn is the out-of-service time of counting yield when vibration durable trouble spot damage ratio is 1 respectively, by m potential thin spot at vibration condition W ₀₁under starting fault-time be designated as t _v1, t _v2..., t _vjt _vm, j=1,2 ... m; By m potential thin spot at vibration condition W ₀₂under starting fault-time be designated as t' _v1, t' _v2..., t' _vj,t' _vm, by a jth weak link point at vibration condition W ₀₁with vibration condition W ₀₂starting fault-time under condition substitutes into formula:

$\frac{{t_{\mathrm{vi}}}^{\′}}{t_{\mathrm{vi}}}={\left(\frac{W_{01}}{W_{02}}\right)}^{b_{\mathrm{vi}}}\·\·\·\left[11\right]$

Obtain the constant factor b of a jth trouble spot _vi; The speedup factor of m incipient fault point is carried out arithmetic mean, obtains vibrating speedup factor b _v:

$b_V=\frac{1}{m}\underset{1}{\overset{m}{\mathrm{\Σ}}}{b}_{\mathrm{vj}}\·\·\·\left[12\right]$

7.2, calculate at vibration stress application time T ₁' under vibration value W _b:

$W_b=W_a\×{\left(\frac{{T_0}^{\′}}{{T_1}^{\′}}\right)}^{\frac{1}{b_V}}\·\·\·\left[13\right]$

8, test is implemented and test findings assessment: integrated temperature and vibration stress condition, and carry out test according to the accelerated test condition after comprehensive, after off-test, according to the following formula to the one-sided confidence lower limit θ of mean time between failures MTBF under given degree of confidence of product _lassess:

${\mathrm{\θ}}_L\≥\frac{2T_0}{{\mathrm{\χ}}_{(1-c)(2r+2)}^2}\·\·\·\left[14\right]$

In formula: r is at reliability accelerated test time T ₁the chargeable fault number of interior appearance;

C is degree of confidence, C=0 ~ 1.

Embodiment:

The object that present case is selected is radio interface unit, its mean time between failures minimum acceptable value is 3000 hours, install and aircraft electronic equipment rack, based on environmental simulation reliability test sectional plane as shown in Figure 1, Reliability Enhancement Testing was carried out in early stage, the working stress limit obtained is: temperature :-80 DEG C ~ 110 DEG C, vibration :≤0.5g ²/ Hz; According to ordering party's requirement, the test period under Fig. 1 section is 30000 hours, designed reliability accelerated test scheme.

1, the digital prototype model of electronic product is built: product establishes according to design information and comprises casing structure, 10 modules, and 272 kinds of models, 10494 components and parts are at interior digital prototype model;

2, thermal stress state and vibration stress state analysis: on the digital prototype model basis built, according to Fig. 1 section, carry out flow dynamics analysis and Finite element analysis on vibration, obtain heat and vibration microstress state that interiors of products comprises cabinet, module and components and parts;

3, the failure mechanism of electronic product is determined: according to thermal stress state and vibration stress state analysis result, in conjunction with the fault mode of electronic product, impact and HAZAN report, outfield and laboratory fault data, determine the main incipient fault components and parts of radio interface unit and fault mode thereof and failure mechanism, as shown in table 1, have 10 heat fatigue thin spots and 5 vibrating fatigue thin spots.

4, the physics model of failure of electronic product is determined: the failure mechanism of his-and-hers watches 1 incipient fault components and parts is analyzed, determine the physics model of failure of radio interface unit, and the model parameter such as geometrical structure parameter, material properties, stress parameters, the Modifying model factor of each fault components and parts is arranged;

5, the temperature conditions of given reliability accelerated test: low temperature :-65 DEG C, duration 30min; High temperature: 85 DEG C, duration 90min; Temperature variability: 15 DEG C/min.A cycling time is 140min, as shown in Figure 3.

6, accelerated test time T is calculated ₁:

6.1, accounting temperature condition speedup factor τ _v: according to the physics model of failure of electronic product, with 2143 Circulation Reliability Tests sections of 30000 hours correspondences for input calculates the mean failure rate start time of accelerating under temperature stress condition, by analyzing lower 10 the potential thin spots of heat fatigue of normal condition, calculate each incipient fault point under Fig. 1 temperature conditions and Fig. 3 temperature conditions under starting fault-time and speedup factor, as shown in table 2; Speedup factor according to incipient fault point carries out arithmetic mean, obtains product speedup factor:

${\mathrm{\τ}}_V=\frac{1}{10}\mathrm{\Σ}{\mathrm{\τ}}_{\mathrm{Vi}}=\frac{1}{10}(4.6+7.0+7.8+4.3+7.4+4.5+4.6+4.4+4.2+4.0)=5.25$

6.2, accelerated test time T is calculated ₁:

$T_1=\frac{T_0}{{\mathrm{\τ}}_V\×t_1}=\frac{3000}{5.25\×140/60}=952.4h$

7, the vibration condition of reliability accelerated test is calculated: with the vibration condition of the reliability test sectional plane based on environmental simulation and corresponding vibration stress application time T ₀' be input parameter, calculate accelerated test time T ₁internal vibration stress application time T ₁' vibration value, concrete grammar is as follows:

7.1, vibration speedup factor b is calculated _v:

Shape vibration value 0.001g is being composed respectively with Fig. 2 ²/ Hz and 0.005g ²the vibrating fatigue damage model drawn under/Hz condition is the out-of-service time of counting yield when vibration durable trouble spot damage ratio is 1 respectively, by each potential thin spot at vibration condition W ₀₁: 0.001g ²the average and W starting fault-time that/Hz is corresponding ₀₁: 0.005g ²starting average substitution fault-time formula under/Hz condition

$\frac{{t_{\mathrm{vi}}}^{\′}}{t_{\mathrm{vi}}}={\left(\frac{W_{01}}{W_{02}}\right)}^{b_{\mathrm{vi}}}\·\·\·\left[15\right]$

The vibration speedup factor of each potential thin spot can be obtained, as shown in table 3;

In his-and-hers watches 3, the speedup factor of 5 potential thin spots carries out arithmetic mean, obtains product speedup factor:

$b_V=\frac{1}{5}\mathrm{\Σ}{b}_{\mathrm{Vi}}=\frac{1}{5}(3.198+3.203+3.2+3.202+3.199)=3.2$

7.2, calculate at vibration stress application time T ₁' under vibration value W _b:

Rule of thumb, 140min cycling time, interior front 20min did not apply vibration in figure 3, and rear 120min applies the maximum vibration of twice 3min, with the maximum vibration (0.005g in Fig. 1 Movement in profile 30000 hours ²/ Hz) equivalent damage; All the other 114min apply minimum vibration, with the minimum vibration (0.001g in Fig. 1 Movement in profile 30000h time ²/ Hz) equivalent damage.

maximum vibration value W ₀calculate with application time:

According to Fig. 1 section, often circulation has the 0.005g of 6min ²/ Hz maximum vibration, the maximum vibration T.T. running 30000h is 2143*6=12858min; According to total about 952.4*60/140=408 the circulation of acceleration environment, maximum vibration value T.T. is 408*6=2448min, maximum vibration value:

$W_0=0.005\×{\left(\frac{12858}{2448}\right)}^{\frac{1}{3.2}}=0.0084g^2/\mathrm{Hz}$

minimum vibration value W ₁calculate with application time:

According to Fig. 1 section, the 0.001g of the 714min that often circulates ²/ Hz minimum vibration, running 30000h minimum vibration T.T. is 2143*714=1530102min; According to total about 408 circulations of acceleration environment, minimum vibration value T.T. is 408*114=46512min, minimum vibration value:

$W_1=0.001\×{\left(\frac{1530102}{46512}\right)}^{\frac{1}{3.2}}=0.003g^2/\mathrm{Hz}$

8, test is implemented and test findings assessment:

Radio interface unit tested products has carried out the reliability accelerated test of 952.4h under accumulative Fig. 3 section, the fail-test based on environmental simulation of 30000h is carried out in equivalence under Fig. 1 section, there are 3 chargeable faults in process of the test, assess according to the following formula:

$\mathrm{\θ}\≥\frac{2T}{{\mathrm{\χ}}_{(1-c)(2r+2)}^2}$

The equivalent test time, T got 30000 hours, and chargeable fault number r gets 3, and degree of confidence c gets 70%, and substituting into above formula can obtain

$\mathrm{\θ}\≥\frac{2\×30000}{{\mathrm{\χ}}_{\mathrm{0.3,8}}^2}\≈6300h$

Therefore, after the end of the reliability accelerated test time of 952.4h, under 70% degree of confidence, the mean time between failures one-sided confidence lower limit of radio interface unit tested products is 6300h.

Table 1 radio interface unit incipient fault components and parts and fault mode thereof and failure mechanism

The potential thin spot speedup factor of table 2 radio interface unit 10 heat fatigues

The potential thin spot speedup factor of table 3 radio interface unit 5 vibrating fatigues

Claims (1)

1. based on an electronic product reliability accelerated test method for faulty physical, it is characterized in that: the step of carrying out electronic product reliability accelerated test is as follows:

1.1, the digital prototype model of electronic product is built: digital prototype model refers to two-dimensional digital PM prototype model or 3-dimensional digital PM prototype model, and electronic product comprises cabinet, support, module, circuit board and components and parts;

1.2, thermal stress state and vibration stress state analysis: adopt the thermal stress state of finite simulation element analysis software analytical electron product under load-up condition and vibration stress state, load-up condition refers to environmental load and operating load;

1.3, the failure mechanism of electronic product is determined: according to thermal stress state that electronic product bears and vibration stress state, in conjunction with the fault mode of electronic product, impact and HAZAN report, outfield and laboratory fault data, determine the dominant failure position of electronic product, failed module, disable system plate and incipient fault components and parts, and failure mechanism.

1.4, the physics model of failure of electronic product is determined: according to the failure mechanism of incipient fault components and parts, determine the physics model of failure of electronic product, the model parameters such as the geometrical structure parameter of incipient fault components and parts, material properties, stress parameters, the Modifying model factor are set;

1.5, the temperature conditions of given reliability accelerated test: high temperature: the upper limit of the temperature range limit provided by test electron product deducts 10 DEG C ~ 20 DEG C, and the duration is that temperature stabilization times adds by the test electron product test time; Low temperature: the lower limit of the temperature range limit provided by test electron product adds 5 DEG C ~ 10 DEG C, and the duration is that temperature stabilization times adds by the test electron product test time; Rate of temperature change: 5 DEG C/min ~ 15 DEG C/min; :

1.6, accelerated test time T is calculated ₁: with by test electron product based on the temperature conditions in the reliability test sectional plane of environmental simulation and test period T ₀for input parameter, calculate the accelerated test time T under the temperature conditions provided in given reliability accelerated test ₁, concrete grammar is as follows:

1.6.1, accounting temperature condition speedup factor τ _v: according to the physics model of failure of electronic product, calculate the damage under the incipient fault components and parts temperature conditions in the reliability test sectional plane of environmental simulation, obtain n potential thin spot N of thermal fatigue failure under the temperature conditions continuous action in the reliability test sectional plane of environmental simulation ₁, N ₂..., N _n, starting fault cycles number of n potential thin spot is designated as N respectively _t1, N _t2... N _ti... N _tn, i=1,2 ... n; Calculate the damage at the temperature conditions of given reliability accelerated test, the starting fault cycles number obtaining n potential thin spot is designated as N' respectively _t1, N' _t2... N' _ti... N' _tn; The speedup factor τ of i-th trouble spot _vi:

${\mathrm{\τ}}_{\mathrm{Vi}}=\frac{N_{\mathrm{Ti}}}{{N^{\′}}_{\mathrm{Ti}}}...\left[1\right]$

The speedup factor of n incipient fault point is carried out arithmetic mean, obtains product temperature speedup factor τ _v:

${\mathrm{\τ}}_V=\frac{1}{n}\underset{1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\τ}}_{\mathrm{Vi}}...\left[2\right]$

1.6.2, accelerated test time T is calculated ₁:

$T_1=\frac{T_0}{{\mathrm{\τ}}_V\×{\mathrm{\τ}}_1}...\left[3\right]$

Wherein, t ₁for the temperature conditions time of given reliability accelerated test;

1.7, the vibration condition of reliability accelerated test is calculated: with the vibration condition of the reliability test sectional plane based on environmental simulation and corresponding vibration stress application time T ' ₀for input parameter, calculate accelerated test time T ₁internal vibration stress application time T ' ₁vibration value, concrete grammar is as follows:

1.7.1 vibration speedup factor b, is calculated _v: according to the physics model of failure of electronic product, calculate the damage under the incipient fault components and parts vibration condition in the reliability test sectional plane of environmental simulation, obtain product vibration condition W in based on the reliability test sectional plane of environmental simulation _am the potential thin spot that lower vibrating fatigue lost efficacy, respectively at vibration condition W ₀₁with vibration condition W ₀₂under, the vibrating fatigue damage model drawn is the out-of-service time of counting yield when vibration durable trouble spot damage ratio is 1 respectively, by m potential thin spot at vibration condition W ₀₁under starting fault-time be designated as t _v1, t _v2..., t _vjt _vm, j=1,2 ... m; By m potential thin spot at vibration condition W ₀₂under starting fault-time be designated as t' _v1, t' _v2..., t' _vj,t' _vm, by a jth weak link point at vibration condition W ₀₁with vibration condition W ₀₂starting fault-time under condition substitutes into formula:

$\frac{{t_{\mathrm{vi}}}^{\′}}{t_{\mathrm{vi}}}={\left(\frac{W_{01}}{W_{02}}\right)}^{b_{\mathrm{vi}}}...\left[4\right]$

Obtain the constant factor b of a jth trouble spot _vi; The speedup factor of m incipient fault point is carried out arithmetic mean, obtains vibrating speedup factor b _v:

$b_V=\frac{1}{m}\underset{1}{\overset{m}{\mathrm{\Σ}}}{b}_{\mathrm{vj}}...\left[5\right]$

1.7.2, calculate at vibration stress application time T ' ₁under vibration value W _b:

$W_b=W_a\×{\left(\frac{{T_0}^{\′}}{{T_1}^{\′}}\right)}^{\frac{1}{b_V}}...\left[6\right]$

1.8, test is implemented and test findings assessment: integrated temperature and vibration stress condition, and carry out test according to the accelerated test condition after comprehensive, after off-test, according to the following formula to the one-sided confidence lower limit θ of mean time between failures MTBF under given degree of confidence of product _lassess:

${\mathrm{\θ}}_L\≥\frac{{2T}_0}{{\mathrm{\χ}}_{(1-c),(2r+2)}^2}...\left[7\right]$ In formula: r is at reliability accelerated test time T ₁the chargeable fault number of interior appearance;

C is degree of confidence, C=0 ~ 1.