Reliability and Failure of Electronic Materials and Devices 1st. Edition by Milton Ohring | 9780125249850 | 125249853 | Holooly

Electronic Devices and Circuits

Reliability and Failure of Electronic Materials and Devices

19 SOLVED PROBLEMS

Question: 11.1

What is the difference in intensity of X-rays penetrating a pure Si wafer 0.05 cm thick relative to this same wafer that is patterned with a 1 μm thick Au bond pad? Assume that the operating X-ray voltage is 20 kV. Is the contrast better at 100 kV? ...

Verified Answer:

Using Eq. 11-1, for the Si wafer alone

I/I_...

Question: 9.3

The solder of Fig. 9-12 undergoes 10³ reversals at a strain of 1.3 × 10^-3. How many more cycles can the solder sustain before it fails at the larger strain of 10^-2? ...

Verified Answer:

Noting that

2N_{f}

at these respect...

Question: 9.4

Accelerated temperature cycling of solder joints on a 256 pin quad flat package (QFP) was carried out at a frequency of 1 cycle/45 min over the range -40 to 125°C. The Weibull cumulative failure distribution was found to be of the form Fs(t) = 1 – exp[-(t/42,900)^1.27], where t is the time in ...

Verified Answer:

a. Substituting in Eq. 9-36, noting that 1 cycle/4...

Question: 9.2

In flip-chip interconnections using 95Pb-5Sn solder, suppose that stresses encountered in service fluctuate between σ/G = 7 x 10^-4 and 1 x 10^-3 at temperatures between 25°C and 35°C. A measure of contact degradation is taken as the ratio of creep strains at the two stress levels. What is the ...

Verified Answer:

We refer to the high stress/temperature state as 2...

Question: 9.1

Assuming representative values of Z* = -10, Q* = 10 kJ/mol, je = 1 X 10^10 A/m², ρ = 1 X 10^-7 Ω-m, T= l000 K and dT/dx = lO^7 K/m, does electromigration or thermomigration dominate? ...

Verified Answer:

Substituting in Eq. 9-6 we have

\frac{J_{e}...

Question: 8.1

Consider a ceramic package where the solder glass used has the following properties; E(g) = 0.7 x 10^6 kg/cm², v (g) = 0.27, α(g) = 6.8 x 10^-6 °C^-1 Similarly, for the alumina ceramic, E (c) = 3.5 x 10^6 kg/cm², v(c) = 0.25, α(c) = 7.2 X 10^-6 °C^-1. If the seal processing temperature is 450°C, ...

Verified Answer:

It is assumed that all stresses are relieved at [l...

Question: 7.2

Estimate the alpha particle flux from an Al2O3 package containing 1 ppm U^238 per gram of ceramic. Assume that only 25% of the alphas generated escape the package from a depth of 14 μm or less, and that the density of Al2O3 is 3.9 g/cm³. ...

Verified Answer:

ln 1

cm^{3}

of

Al_{2}O_{3}[/...

Question: 6.2

What human-body voltage pulse is necessary to cause a 1 cm long, 20 μm diameter gold wire to melt under adiabatic conditions? Gold has a melting temperature (TM) of 1064°C, a density (ρ) of 19.3 g/cm³, a heat capacity (c) of 0.13 J/g-K, and a resistivity given by 2.4 × [1 + 0.0034(T°C – 20)] μΩ-cm. ...

Verified Answer:

According to Eq. 6-36, the human-body voltage is g...

Question: 6.1

A pulse of 4500 V is discharged from a person into a p-n junction. The junction area is 5 x 10^-7 cm² and the resistance is 20 Ω. Assume that the voltage across the device is negligible compared with that of the ESD pulse. a. Over what time span does the discharge occur? b. What is the maximum ...

Verified Answer:

a. For the human body model the time constant is [...

Question: 5.1

Consider the contact structure of Fig. 5-7c consisting of a pure Al film of indicated geometry over Si. Calculate the depth (y) of Si depletion in the wafer during a processing heat treatment of 1 h at 450°C, where the solubility (S) of Si in Al is 0.5 wt%. The respective densities are ρsi and ρAl ...

Verified Answer:

The amount of Si needed to saturate the metal cont...

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