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第四单元 PowerPoint PPT Presentation


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第四单元. 可靠性试验. 可靠性试验的特点. 具有破坏性 — 以发现产品在设计、材料和工艺方面的各种缺陷为目的 必须施加应力 — 环境应力或工作应力 可以给出可靠性指标. 可靠性试验的分类. 可靠性筛选试验 可靠性测定实验 可靠性增长试验 可靠性鉴定和验收试验 加速寿命试验. 环境应力筛选试验. ESS (Environment stress screen) 是通过向电子产品施加合理的环境应力和电应力,将其内部的潜在缺陷加速变成故障,并通过检验发现和排除的过程,是一种工艺手段。其目的是筛选剔除早期失效的产品,提高产品的可靠性水平。. 100% 筛选.

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第四单元

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ESS (Environment stress screen)

100%




GJB1032

  • 40h;

  • 5min;

  • ():


:



:



(MLE)

MLEMaximum Likelihood Estimation)


n n :


:



MLE

(1)


(2)Weibull MLE


(3)MLE




(N,,t0)


(N,,tr)


(N,,t0)

X :

n :


(0,t):

r

dt:


:

:


(n,,r) (n, ,t0)

  • Weibull



m


t0




(0,1),

1


  • 1-



  • :~



98% 99%

99%

99.5%

95% 97.5%

90% 95%

80% 90%

60% 80%

95% 97.5%

90% 95%

80% 90%

60%80%


  • 2010073020190%290%

  • : (1)

  • (2)


n:


  • 2000.95

  • ,:


  • n-1t:

:


  • m:

    :

  • 1-:


1r<n


2r=n

  • tn-1




  • MTBFMTBF

  • MTBF10%MTBF

  • 0.3<<0.7

  • MTBF=50-20000,10-25; MTBF>2000MTBF


-


  • :


AMSAA

  • .:



Tj

m




  • (N,n,C) PL(P) x:


01:


(1)

  • n:

01:




(2)

  • nt0r:

  • rC

  • r>C

01:


TC

TC



(3)

r

T>T(A)

T<T(R)

T(R)<T<T(A)

T(R)

(T1,1)

T(A)

(T1,1)

-h1

h0

T



r

T(R)

r0

T(A)

(T1,1)

sr0

T

-h1

h0


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