Protective coatings of electronics under harsh thermal shock

Pippola, J.; Marttila, Tuomas; Frisk, Laura

doi:10.1016/j.microrel.2014.07.106

Cited by 10 publications

(9 citation statements)

References 5 publications

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“…Conformal coating, a thin protective polymeric film that conforms to the contours of Printed Circuit Boards (PCB) and electronic components acts as a physical barrier against various environmental, mechanical, electrical, and chemical effects [2][3][4][5][6]. Five main families of conformal coatings exist on the market that differ by their chemistry (molecular structure, polymer backbone) and their physical properties [7].…”

Section: Introductionmentioning

confidence: 99%

“…One of the characteristics of silicones is their large coefficient of thermal expansion (CTE), which is very different from the CTE of the PCB, electronic components, and solder joints. [2,3,[9][10][11]. Most PCBs have a CTE lower than 20 ppm/ • C [3,[9][10][11], and most solder joints have a CTE lower than 25 ppm/ • C [10,11], while silicone conformal coatings have CTE values above 200 ppm/ • C [3].…”

Section: Introductionmentioning

confidence: 99%

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Method to Predict Performances of PCB Silicone Conformal Coating under Thermal Aging

Zhang

Descamps²

2022

Applied Sciences

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The stability of print circuit board (PCB) conformal coating is critical to guarantee the long-term performance of electronic components on PCB boards. Coating exposure to thermal shock or temperature cycles may initiate cracks, a common failure mechanism of conformal coatings. Different simplified approaches are compared to help identify desired mechanical profiles for coatings to be used in a harsh environment, focusing on silicone characterized by low rigidity and high deformability compared to alternative chemistries. Evaluation of the bi-material strip bending test method appears not to be effective in the conformal coating selection. The large difference between the coating’s elastic modulus of silicones compared to substrate modulus allows the use of a simplified formula to calculate the stress associated with the coefficient of thermal expansion (CTE) mismatch, the silicone accommodating displacement imposed by thermal changes. Both lateral tensile stress and local shear stress near the edge are estimated, with local shear stress decreasing quickly and moving apart from the edge with the stress relaxation preventing coating delamination. Predictions of simplified models agree with both results of grid-independent finite element analysis (FEA) models and observations of test pieces submitted to temperature cycles. This demonstrates the ability to use simplified models to predict coating’s performances under thermal aging and help in product selection depending on the working environment.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Method to Predict Performances of PCB Silicone Conformal Coating under Thermal Aging

Zhang

Descamps²

2022

Applied Sciences

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“…In this paper, a 0.1-1.2 GHz CMOS PA has been fabricated and tested under thermal shock test with RF stress from −40 • C to 125 • C. The thermal shock test can well evaluate the performance of PA under extreme temperature changes [13], but the testing time of the thermal shock test is prolonged [14]- [15]. In this paper, RF stress is introduced into the thermal shock test, which can well evaluate the performance of PA under extreme temperature change and dramatically shortens the testing time of the thermal shock test.…”

Section: Introductionmentioning

confidence: 99%

An RF Stress-Based Thermal Shock Test Method for a CMOS Power Amplifier

Zhou

Jian

2021

IEEE J. Electron Devices Soc.

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To accelerate the degradation of critical specifications of CMOS power amplifiers (PAs), this paper proposes a new measurement method that introduces radio frequency (RF) stress in the thermal shock test of CMOS PAs. The experimental results show that the proposed method is effective. The degradation of key PA specifications such as output power and power-added efficiency can accelerate under RF stress. Its degradation speed is faster than that under no RF stress. Possible reasons for the degradation of crucial PA specifications accelerated by RF stress are discussed and analyzed in detail in this paper. The method proposed in this paper can effectively reduce the measurement time and cost to study the degradation of critical specifications of the CMOS-based PA. This method can be used for scientific research on the performance degradation of microwave/RF circuits and devices and aging experiments of electronic products before they leave the factory.INDEX TERMS Thermal shock test, radio frequency stress, CMOS power amplifier, performance degradation.

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“…Currently, there are mainly three kinds of typical VDS tools, including the Baker Hughes Verti-Trak system, Schlumberger Power-V system, Halliburton Sperry-sun V-Pilot system [2,6,8]. All of them have sensitive and expensive electronic components [9] which has low reliability under complex conditions such as high temperature (more than 200℃) and extreme vibration in ultra-deep wells [10][11][12][13]. In recent years, the Mechanical Automatic Vertical Drilling System (MVDS) [14][15][16] which working in full mechanical mode and more economical, safety and reliability has gradually attracted attention.…”

Section: Introductionmentioning

confidence: 99%