Impact of Process-Related Flux Contamination on the Electronics Reliability Issues Under Detrimental Climatic Conditions

Piotrowska, Kamila; Laganá, Simone; Jellesen, Morten Stendahl; Ambat, Rajan

doi:10.23919/panpacific.2019.8696890

Cited by 6 publications

(8 citation statements)

References 8 publications

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“…The nature of the residue is usually in a concealed form with active components embedded within the resin formed as a film. It has been reported that this residue film over exposure to humidity changes in morphology, leading to release of acidic compounds causing corrosion reliability issues [6][7]. Together with the climatic exposure conditions during service life, it determines the humidity robustness of electronic systems.…”

Section: Discussionmentioning

confidence: 99%

“…While the activator components from the SP formulation are concealed within or underneath the film-former layer of the residues after the soldering process [6][7] (confirmed by similar low levels of conductivity for all as-received PCBAs), the amount of activator and the robustness of the film former layer barrier are dependent on the solder flux chemistry and soldering profile. Morphology changes shown in Fig.…”

Section: Morphology Of the Solder Paste Residue On Pcbasmentioning

confidence: 99%

“…Unlike for wave soldering process, no-clean flux residues from reflow process exist on the PCBA surface as localized residues under the components due to the application process. The amount of flux applied in the reflow process is specific to the component footprint areas, therefore trapped residues can be found under components [4][5][6]. After soldering, the acidic compounds of the SP are concealed within/underneath the filmformer layer (unevaporated resin).…”

Section: Introductionmentioning

confidence: 99%

“…However, upon humidity exposure, the appearance and morphology of the film-former can change [7]. Deterioration of the film-former results in release of active compounds such as WOAs below the SMD [6]. WOAs are hygroscopic and tend to absorb moisture from the surrounding environment.…”

Section: Introductionmentioning

confidence: 99%

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Reflow Residues on Printed Circuit Board Assemblies and Interaction With Humidity

Conseil-Gudla

Ambat

2021

IEEE Trans. Device Mater. Relib.

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Ionic residues resulting from the soldering process is an important parameter in connection with humidity robustness of Printed Circuit Board Assemblies (PCBAs) due to their ability to enhance moisture absorption and surface conductivity. For reflow process, residues are trapped under the components, and the morphology of the residues can change with humidity exposure resulting in the release of ionic components.In this work, trapped residues below the components from reflow process of several commercial PCBAs were characterized before and after exposure to humidity conditions. PCBAs used for the analysis had undergone multiple reflow heating profiles by single and double reflow plus additional passes to understand heating effects.The morphology change of the trapped residues under components upon humidity exposure was observed using optical and scanning electron microscopy. The conductivity of the localized extracted solutions was measured and NaCl equivalency was determined. The solder paste materials were analysed for their water sorption property, while the effect of humidity on electrical property was assessed using electrochemical impedance spectroscopy using test PCBs.The results show that the change in morphology and level of activator release of residues were a function of the flux type, PCBA characteristics such as component standoff height and number of reflow cycles. Water layer formation upon humidity exposure and electrical properties on test PCBs are correlated with water sorption of the flux part.

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Section: Discussionmentioning

confidence: 99%

Section: Morphology Of the Solder Paste Residue On Pcbasmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Reflow Residues on Printed Circuit Board Assemblies and Interaction With Humidity

Conseil-Gudla

Ambat

2021

IEEE Trans. Device Mater. Relib.

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“…The conventional joining processes adopted in the electronic industry such as brazing and soldering results in contamination of devices due to the fluxes used. 13 Moreover, the useful microstructural features and the required properties will be lost when hypereutectic Al−Si undergoes multiple steps of joining processes. Thus, there is a necessity to devise an appropriate joining methodology to preserve required functionalities.…”

Section: ■ Introductionmentioning

confidence: 99%

On Simultaneous Sintering and Joining by Electric Current Activated Interfacial Eutectic Melting of Al–Si for Electronic Packaging Applications

Thiagarajan

Kamaraj

Jayapalan

et al. 2022

ACS Appl. Eng. Mater.

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Worldwide, exponential growth in energy consumption demands energy efficient and innovative material synthesis techniques. Conventional material joining processes for electronic applications such as brazing and soldering have limitations due to chemically distinct interface materials and multiple step processing. In this work, we have demonstrated a single step metal−ceramic joining and a single step metal−metal joining, without any interface material, using electric current activated eutectic melting during spark plasma sintering. Particulates of hypereutectic Al−Si, a potential candidate for electronic packaging of high-power density electronic components, were sintered and simultaneously joined with a solid alumina substrate. Similarly, hypereutectic Al−Si particulates were sintered and joined with solid aluminum alloy AA6061 as well. The selective interfacial eutectic melting between Al and Si, due to the resistance offered to electric current, aids in simultaneous joining with solid substrates apart from aiding in densification of particulate aggregates. The Al−Si regions at joint interfaces are characterized by finer eutectic silicon formation. The interlaminar shear strengths (ILSS) of Al−Si/AA6061 joints were nearly 3-fold (≈110 MPa) higher than that of Al−Si/Al 2 O 3 joints due to the nature bonding. The absence of a chemically distinct interfacial layer and existence of finer microstructure at the joint interface resulted in excellent structural integrity. Our work paves the way for employing electric current assisted eutectic melting to create metal−ceramic and metal−metal joints.

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Effect of flux activator in reflow process related flux residue on the climatic reliability of surface-mount electronic devices

Lakkaraju

Jellesen

et al. 2023

J Mater Sci: Mater Electron

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This paper investigated the effect of flux activator used in reflow flux formulation on the electrochemical reliability of electronic devices. The focuses were placed on the perspective of surface insulation resistance (SIR), cleanliness, and its morphology transformation and redistribution behavior of flux residue under climatic exposure. Standardized accelerated climatic test on SIR comb-structure pattern was performed to benchmark the humidity interaction of the tested flux formulations used in solder paste. The influence of stand-off height for the surface-mount component on the humidity robustness was analyzed using an in-house designed dummy test rig and electrochemical impedance spectroscopy. Scanning electron microscopy and conductivity measurement was used to understand the hydrolytic degradation of the flux residue and the release of the conductive ionic residues during climatic exposure. Results indicate the spreading area and the hydrolytic degradation behavior of the flux residue were influenced by the type of flux activators used in flux formulation. The climatic reliability was influenced by the combined effect of the aggressiveness of flux activator and the spreading of the flux residue. However, result also shows that the climatic reliability of the surface-mount device can be improved by increasing the stand-off height of the components together with selected flux formulation.

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Impact of Process-Related Flux Contamination on the Electronics Reliability Issues Under Detrimental Climatic Conditions

Cited by 6 publications

References 8 publications

Reflow Residues on Printed Circuit Board Assemblies and Interaction With Humidity

Reflow Residues on Printed Circuit Board Assemblies and Interaction With Humidity

On Simultaneous Sintering and Joining by Electric Current Activated Interfacial Eutectic Melting of Al–Si for Electronic Packaging Applications

Effect of flux activator in reflow process related flux residue on the climatic reliability of surface-mount electronic devices

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