The Influence of Plastic Encapsulants and Passivation Layers on the Corrosion of Thin Aluminium Films Subjected to Humidity Stress

Sim, Seong-Ju; Lawson, R W

doi:10.1109/irps.1979.362878

Cited by 23 publications

(7 citation statements)

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“…100% relative humidity). From a review of this literature, the failure modes dependent on moisture and ionic contamination are bond pad corrosion [20,[60][61][62] and MOSFET threshold voltage shifts, which may be caused by damage to the gate oxide from ionic contamination or water-enhanced charged-carrier injection [63][64][65][66].…”

Section: Current and Future Ageing Testsmentioning

confidence: 99%

Silicone encapsulation of thin-film SiO_x, SiO_xN_y and SiC for modern electronic medical implants: a comparative long-term ageing study

et al. 2021

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Objective. Ensuring the longevity of implantable devices is critical for their clinical usefulness. This is commonly achieved by hermetically sealing the sensitive electronics in a water impermeable housing, however, this method limits miniaturisation. Alternatively, silicone encapsulation has demonstrated long-term protection of implanted thick-film electronic devices. However, much of the current conformal packaging research is focused on more rigid coatings, such as parylene, liquid crystal polymers and novel inorganic layers. Here, we consider the potential of silicone to protect implants using thin-film technology with features 33 times smaller than thick-film counterparts. Approach. Aluminium interdigitated comb structures under plasma-enhanced chemical vapour deposited passivation (SiO x , SiO x N y , SiO x N y + SiC) were encapsulated in medical grade silicones, with a total of six passivation/silicone combinations. Samples were aged in phosphate-buffered saline at 67 ∘ C for up to 694 days under a continuous ±5 V biphasic waveform. Periodic electrochemical impedance spectroscopy measurements monitored for leakage currents and degradation of the metal traces. Fourier-transform infrared spectroscopy, x-ray photoelectron spectroscopy, focused-ion-beam and scanning-electron- microscopy were employed to determine any encapsulation material changes. Main results. No silicone delamination, passivation dissolution, or metal corrosion was observed during ageing. Impedances greater than 100 GΩ were maintained between the aluminium tracks for silicone encapsulation over SiO x N y and SiC passivations. For these samples the only observed failure mode was open-circuit wire bonds. In contrast, progressive hydration of the SiO x caused its resistance to decrease by an order of magnitude. Significance. These results demonstrate silicone encapsulation offers excellent protection to thin-film conducting tracks when combined with appropriate inorganic thin films. This conclusion corresponds to previous reliability studies of silicone encapsulation in aqueous environments, but with a larger sample size. Therefore, we believe silicone encapsulation to be a realistic means of providing long-term protection for the circuits of implanted electronic medical devices.

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Section: Current and Future Ageing Testsmentioning

confidence: 99%

Silicone encapsulation of thin-film SiO_x, SiO_xN_y and SiC for modern electronic medical implants: a comparative long-term ageing study

et al. 2021

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“…Al Al+++ + 3e E [12] 3H + 3e = 3/2H2, [13] and the chemical dissolution reaction by summation is Al + 3H -AlH± + 3/2 H2. [14] Reactions at Negative Metallization: With application of a bias, H2 will be evolved at the negative Al track which will make the originally near-neutral solution alkaline, according to Eq.…”

Section: Anodical Dissolution Versusgasevolutionmentioning

confidence: 99%

Corrosion of Aluminum Metallization Through Flawed Polymer Passivation Layers; In-Situ Microscopy

Will

Janora

McMullen

et al. 1987

25th International Reliability Physics Symposium

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Aluminum corrosion in a polymer-coated circuit model was studied using in-situ microscopy coupled with time-lapse video recording.Pinholes in the polymer coating and exposure to water with bias voltage of 40V applied between adjacent aluminum tracks resulted in fast anode corrosion, accompanied by gas evolution. A mathematical model is developed that is in good agreement with the observed current-time relationship. The rate of corrosion is controlled by the resistance of a 6000A thick water film occupying the space of the corroded Al film between wafer and polymer coating.A tentative corrosion mechanism is proposed.

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“…Incorporated ionic contaminants including Br − , Cl − , Na + , K + and so on can change the character of the solution to be more reactive and therefore speed up the process massively [2, 6, 7, 11, 17, 18]. Multiple potential sources of ionic species have been detected in semiconductor device manufacturing [10, 15, 19], which can be divided into process‐related sources (e.g. residues from etching), material‐related sources (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…the environment. Since soft‐moulds are highly hydrophilic and hence absorb moisture, ions in solution can easily diffuse through the encapsulant and attack the underlying metal structures [19, 20].…”

Section: Introductionmentioning

confidence: 99%

Temperature–humidity–bias testing on insulated‐gate bipolartransistor modules – failure modes and acceleration due to high voltage

Zorn

Kaminski

2015

IET Power Electronics

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The temperature-humidity-bias (THB) test is the standard for accelerated stress testing with respect to corrosion and other humidity driven degradation mechanisms. Usually, 1000 h tests at 85°C and 85% relative humidity are used to predict up to 25 years of operation. The bias is usually limited to 80 V in order to fulfil the respective standards. Nevertheless, THB tests on 1700 V insulated-gate bipolar transistor (IGBT)-modules have shown that higher bias is a more severe test condition. The failure analysis confirmed Cu-and Ag-dendrites and corrosion of the aluminium (Al)-chip-metallisation as the relevant failure mechanisms. To determine the acceleration factor due to voltage, 1200 V IGBT modules were tested in THB at 780 V (65% of V CES) and 1080 V (90% of V CES). A characteristic degradation consisting of three phases has been identified. The second phase seems to be determined by Al corrosion and an acceleration factor of about two has been estimated from 780 to 1080 V. Within the third phase, the devices stabilised probably due to localised self-heating. Thus, this degradation mechanism is kind of self-limiting, but the higher leakage also increases the risk of thermal runaway especially when biased close to the rated collector-emitter voltage.

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The Influence of Plastic Encapsulants and Passivation Layers on the Corrosion of Thin Aluminium Films Subjected to Humidity Stress

Cited by 23 publications

References 0 publications

Silicone encapsulation of thin-film SiO_x, SiO_xN_y and SiC for modern electronic medical implants: a comparative long-term ageing study

Silicone encapsulation of thin-film SiO_x, SiO_xN_y and SiC for modern electronic medical implants: a comparative long-term ageing study

Corrosion of Aluminum Metallization Through Flawed Polymer Passivation Layers; In-Situ Microscopy

Temperature–humidity–bias testing on insulated‐gate bipolartransistor modules – failure modes and acceleration due to high voltage

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The Influence of Plastic Encapsulants and Passivation Layers on the Corrosion of Thin Aluminium Films Subjected to Humidity Stress

Cited by 23 publications

References 0 publications

Silicone encapsulation of thin-film SiO x , SiO x N y and SiC for modern electronic medical implants: a comparative long-term ageing study

Silicone encapsulation of thin-film SiO x , SiO x N y and SiC for modern electronic medical implants: a comparative long-term ageing study

Corrosion of Aluminum Metallization Through Flawed Polymer Passivation Layers; In-Situ Microscopy

Temperature–humidity–bias testing on insulated‐gate bipolartransistor modules – failure modes and acceleration due to high voltage

Contact Info

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Silicone encapsulation of thin-film SiO_x, SiO_xN_y and SiC for modern electronic medical implants: a comparative long-term ageing study

Silicone encapsulation of thin-film SiO_x, SiO_xN_y and SiC for modern electronic medical implants: a comparative long-term ageing study