Understanding the use of silicone gels for nonhermetic plastic packaging

Wong, Ching‐Ping; Segelken, J.M.; Balde, J.W.

doi:10.1109/33.48998

Cited by 37 publications

(15 citation statements)

References 9 publications

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“…Glob tops may or may not require a dam around the circuit components. Rubbers and gels usually exert minor stress on chips, wires, and other components due to their low hardness and storage modulus as well as their excellent elasticity and resilience [12], [55], [56]. However, these properties of rubbers and gels greatly limit their mechanical protection against external forces [9].…”

Section: Potting Compounds and Glob Topsmentioning

confidence: 98%

“…Similarly, glob tops can also be either resins or rubbers. They protect semiconductor packages and circuit components from electrical breakdown and chemical species in ambient environment [9], [10], [55], [56]. Therefore, high dielectric strength and low moisture absorption are required.…”

Section: Potting Compounds and Glob Topsmentioning

confidence: 99%

“…The purpose of potting compound is to electrically and chemically protect circuit components without exerting too much stress on them [12], [55], [56]. From the mechanical viewpoint, a low storage modulus (< a few megapascals) is needed to limit the stress resulted from CTE-mismatch.…”

Section: Potting Compounds and Glob Topsmentioning

confidence: 99%

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Survey of High-Temperature Polymeric Encapsulants for Power Electronics Packaging

Yao

Lü

Boroyevich

et al. 2015

IEEE Trans. Compon., Packag. Manufact. Technol.

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Semiconductor encapsulation is crucial to electronic packaging because it provides protection against mechanical stress, electrical breakdown, chemical erosions, α radiations, and so on. Conventional encapsulants are only applicable below 150°C. However, with increasing demand for high-density and high-temperature packaging, encapsulants that are functional at or above 250°C are required. In this paper, five types of encapsulants, including conformal coatings, underfills, molding compounds, potting compounds, and glob tops, are surveyed. First, recommended properties and selection criteria of each type of encapsulant are listed. Second, standard test methods for several crucial properties, including glass-transition temperature (T g ), coefficient of thermal expansion (CTE), dielectric strength, and so on are reviewed. Afterward, commercial products with highoperation temperature are surveyed. However, the results of the survey reveal a lack of high-temperature encapsulants. Therefore, this paper reviews recent progress in achieving encapsulants with both high-temperature capability and satisfactory properties. Material compositions other than epoxy, such as polyimide (PI), bismaleimide (BMI), and cyanate ester (CE), are potential encapsulants for high-temperature (250°C) operation, although their CTE needs to be tailored to limit internal stress. Fillers are reported to be efficient in reducing the CTE. In addition, fillers may also have a beneficial impact on the thermal stability of silicone-based encapsulants, whose high-temperature capability is limited by their thermal instability. IndexTerms-Encapsulant, high-temperature, plastic integrated circuit packaging, power electronic packaging, semiconductor device packaging.

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Section: Potting Compounds and Glob Topsmentioning

confidence: 98%

Section: Potting Compounds and Glob Topsmentioning

confidence: 99%

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Survey of High-Temperature Polymeric Encapsulants for Power Electronics Packaging

Yao

Lü

Boroyevich

et al. 2015

IEEE Trans. Compon., Packag. Manufact. Technol.

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“…There have been problems such as unnecessary tire wear, reduced gas mileage, and less than optimal vehicle performance when tires are over intlated. In addition, under-intlated tires typically result in increased tire wear, decreased vehicle performance, and compromise the ability of the tires to maintain a safe interface with the road Furthermore, in order to improve the reliability of TPMS, packaging design optimization is essentiaL Usually, the pressure sensor die is coated with soft gel in the packaging process [2]. Some researchers have attempted to reveal failure factors of pressure sensor's bond wires [3][4], and some other researchers have focused on single parameter of the die-attaching adhesive affecting the silicon pressure sensor's output characteristics [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Packaging optimization for tire pressure monitoring system

Chen

Zhang

Leng³

et al. 2012

2012 13th International Conference on Electronic Packaging Technology &Amp; High Density Packaging

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In order to improve the reliability of tire pressure monitoring system (TPMS), packaging design optimization is essentiaL In this paper, finite element method (FEM) is used to analyze the effect of packaging processes on the residual stresses of the sensor die and its packaging, The Young's modulus and thickness of the coating material, the dimension effect of the dies and the substrates on which the dies are attached are considered in this paper. Results show the thinner coating gel that has a lower Young's modulus generates lower residual stress and smaller zero offset as weil as sm aller temperature drift to the sensor. For a given coating soft gel, the thermal residual stress decreases with the thickness of adhesive layer decreasing, and the effect is not significant when the thickness of coating gel is smaller than L5mm, Therefore, this value can be decided as the technological parameter. Comparing stainless steel, Kovar and FR-4, the ceramic is more suitable for using as the substrate, The ceramic has lower CTE compared with steel, Kovar and FR-4, therefore the residual thermal stresses resulted from the CTE mismatch are much lower than that of steel, Kovar and FR-4, For a given coating soft gel and substrate, smaller dimension of the dies will benefit the sensor's performance on the residual stresses, For a given coating soft gel, the material of the shells has little effect on the residual stresses of the dies,The above simulation results can be used to guide the tire pressure sensor's packaging design optimization, Based on FEM results, the optimized die-attaching process parameters are proposed, The experiments indicate that the proposed pressure sensor has a stable output voltage and good linearity, and the zero offset and temperature drift of the sensors are also minor.

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“…It is well accepted that the protective action of RTV silicones and other siloxanes on integrated circuits and ceramic substrates is due to the chemical reaction of the silicone with hydroxyl groups on the oxide surface [2], [3]. Not all substrates (e.g., organic polymers) and not all gels or greases (e.g., paraffins), however, have reactive groups.…”

Section: Introductionmentioning

confidence: 99%

Conductive aqueous layer formation at the gel-substrate interface in equilibrium with 100% RH environment

Tencer

2000

IEEE Trans. Comp. Packag. Technol.

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The paper describes results of theoretical modeling and experimental verification of conditions leading to formation of a conductive aqueous layer at the interface between gels and substrates at 100% RH or equivalent (water immersed) conditions. Thermodynamic analysis of clean surfaces and interfaces shows that displacement of the interface between gels and inorganic substrates (e.g., ceramics and integrated circuits) by water is thermodynamically favorable while interfaces gel-organic substrate are stable versus such displacement. The presence of water-soluble contaminant on the substrate will cause formation of water droplets whose diameter can be determined from the balancing of the osmotic and interfacial tension effects. If the total surface coverage by droplets (which is independent of the contaminant particle size distribution) exceeds the critical two-dimensional (2-D) percolation threshold a continuous path of electrical conductivity is formed. For sodium chloride contaminant the critical surface concentration leading to such event was calculated and shown experimentally to be 10 7 g/cm 2 . Inorganic filler in the gel in the amount exceeding the three-dimensional (3-D) percolation limit can cause bulk conductivity of the gel material at high humidity due to formation of an aqueous layer at the gel-filler interface.

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Understanding the use of silicone gels for nonhermetic plastic packaging

Cited by 37 publications

References 9 publications

Survey of High-Temperature Polymeric Encapsulants for Power Electronics Packaging

Survey of High-Temperature Polymeric Encapsulants for Power Electronics Packaging

Packaging optimization for tire pressure monitoring system

Conductive aqueous layer formation at the gel-substrate interface in equilibrium with 100% RH environment

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