Electronic Packaging Research Articles

Co2+-enhanced zinc aluminate microwave dielectric ceramics for electronic packaging to thermally match printed circuit boards

Co²⁺-enhanced zinc aluminate microwave dielectric ceramics for electronic packaging to thermally match printed circuit boards

Fatigue Life Based Study of Electronic Package Mounting Locations on Printed Circuit Boards Subjected to Random Vibration Loads

Fatigue Life Based Study of Electronic Package Mounting Locations on Printed Circuit Boards Subjected to Random Vibration Loads

Modified castor oil-based UV/thermal dual-curing polyurethane acrylate coatings with outstanding comprehensive properties

Due to the fact that single UV-cured coatings frequently fail to fulfill the requirements in terms of depth and chroma, and do not reach the ideal state in terms of comprehensive performance. In order to solve these pain-points more effectively, the sulfhydryl-modified castor oil (COME) was successfully synthesized by introducing β-mercaptoethanol onto the plant-based material castor oil (CO) through the thiol-ene clink reaction. Subsequently, the synthesized polyurethane acrylate prepolymer (COPUA), monomer, photoinitiator and thermocuring agent were used as A component, and COME was used as B component. The two were mixed evenly according to a certain proportion, and the modified castor oil based polyurethane acrylate (COMEPUA) coatings were fabricated by UV/thermal dual-curing technology. Based on a series of performance test outcomes, the coating demonstrates excellent comprehensive properties, encompassing mechanical properties (where the shear strength, tensile strength, elongation at break, and hardness can respectively reach 5.26MPa, 9.92MPa, 132.55%, and 47.77 Shore D), coating properties (where the absorption rates after 72h immersion in water, ethanol, 10wt% HCl, and 10wt% NaOH solvents are respectively 0.66, 17.98, 1.89, and 0.71%, and the volume resistivity and breakdown voltage are respectively 1.74×1016 Ω·cm and 10 KV) and curing properties (where the curing depth can reach 9.82mm, which is significantly higher than 3.51mm of single UV curing, and the colored curing is complete). It can exert protective functions such as anti-corrosion, anti-fouling, and insulation on circuit boards, electronic packaging, and device surfaces, and holds great potential in the application of coating materials.

Effect of B/Pb ion replacement in B2O3-PbO-SiO2 glasses: Structural, thermal, optical and electrical properties

Due to its easy manufacturing process and outstanding physical and chemical characteristics, boron lead silicate glass is widely used in electronic packaging, optical fields, and sensor technology. Herein, new glass samples with different proportions of B2O3/PbO are prepared by a combined melting and annealing process. The glasses undergo structural and thermal characterization to investigate its composition, thermal behavior, optical properties, and dielectric properties. The results show that the glass structure changes gradually as [SiO4] and [PbO4] units were replaced by [BO3] units with increasing B2O3 content. This transformation has an impact on coefficient of thermal expansion and characteristic temperature of the glass. Additionally, it is observed that alterations in structure resulted in a decrease in both optical band gap as well as dielectric constant and loss. These findings provide insights into how variations in the B2O3/PbO ratio influence structural evolution and enhance properties for boron lead silicate glasses. This provides a theoretical basis for further advances to improve material properties and expand optical and electronic applications.

A novel multi-information fusion CNN for defect detection in laser soldering of SAC305

Identification of laser soldering of lead-free solder Sn-3.0Ag-0.5Cu (SAC305) in electronic packaging was still an enormous challenge. It was difficult to detect defects in large-scale production. This work proposed an identification model based on multi-information fusion convolutional neural network (MIFCNN) for inspecting laser soldering process. In this method, the forty images in chronological order and the temperature data were combined as the input to be utilized in detecting defects. The results demonstrated that MIFCNN had best accuracy for three types of joints with accuracy of 98.28 % due to the combination of images and temperature information. The ICNN and TCNN had poor recognition accuracy for the warpage defect with 73.9 % and the poor wetting defect with 66.5 %, respectively. This was because the images and temperature information were the key to identifying the poor wetting defects and warpage defects, respectively. The poor wetting defect could be recognized by difference of contact angle, while the warpage defect could be significantly detected by maximum temperature. This work could help detecting defects of laser soldering in the actual production and widen the application of MIFCNN in the field of laser soldering.

Silicon carbide nanowire-reinforced micro-Ag joint based on pinning effect for power electronics packaging

Low-temperature sintering Ag technology is a feasible approach employed in power electron devices. In this study, the influence of the different amounts (0, 0.03, 0.05, 0.07, 0.10, 0.20 wt%) of silicon carbide nanowires (SiC NWs) on the properties and microstructure of micro-Ag paste sintered at 250 °C without pressure has been investigated. The results exhibit that the bonding strength of the Ag-SiC joint reaches a maximum of 43.57 MPa after doping 0.07 wt% SiC NWs, with an increase of 13 % compared with pure Ag joint. This enhancement mechanism can be owed to the Orowan mechanism and the pinning effect of SiC NWs, which nail at grain boundaries that will restrain the dislocation motion of Ag grains. Meanwhile, the electrical resistivity of Ag-0.07SiC shows a minimum value of 5.20 μΩ cm, approximately 10.65 % lower than pure Ag joint. This is attributed to the well-sintered Ag network and the bridging effect of SiC NWs distributed in Ag particles. Thus, incorporating appropriate content of SiC NWs into micro-Ag paste can strengthen the mechanical performance and electrical conductivity of sintered Ag joint. It is hoped that this research could develop a new micro-Ag paste with outstanding properties that could be employed in high-power electronic devices.

Structures and Performance of a Polybenzoxazine with High Heat Resistance and High-Frequency Low-Dielectric Properties

Benzoxazine is a newly developed thermoset resin that has attracted significant academic and industrial interest due to its excellent properties. However, improving its dielectric performance while maintaining high heat resistant is crucial for expanding its application in 5G electronics. In this study, we designed and synthesized a novel benzoxazine monomer, DFDA-PTB, using p-tert-butylphenol (PTB) as the phenol source and furfuryl diamine (DFDA), derived from furfuryl amine, as the amine source. Two additional benzoxazines with similar structures were also synthesized for comparison. The cured product, poly(DFDA-PTB), was then analyzed to explore the relationship between its structure and properties. The results indicate that the introduction of a furan ring structure enhances thermal stability and reduces the dielectric constant. Additionally, the inclusion of tert-butyl groups further lowers the dielectric constant and dielectric loss. Simulation methods were employed to study the mechanisms behind these improvements. Poly(DFDA-PTB) demonstrated superior dielectric properties, with a dielectric constant of 2.51 and a dielectric loss of 0.0018 at 10 GHz. It also exhibited excellent heat resistance, with a char yield of 45.4% at 800 °C. These properties make poly(DFDA-PTB) a promising candidate for electronic packaging and communication applications.

Borosilicate glass with low dielectric loss and low permittivity for 5G/6G electronic packaging applications

A phase-separated borosilicate glass, with a relative permittivity ranging from 3 to 3.5 and a loss tangent as low as 5.6 × 10−4, is presented for packaging applications for the next generation of mobile communications. Ionic polarizability for each borosilicate composition was calculated from the Clausius–Mossotti relationship for both the vitreous and crystalline structures, and the polarizability difference between the two is proportional to the dielectric loss. Small amounts of alkali modifier were added to improve the glass processability, and the loss tangent increased to the 1–7 × 10−3 range. The resulting glass is phase-separated, which has no impact in the millimeter-wave spectrum, as the wavelengths are considerably greater than the length scale of each immiscible phase.

I Trust the Exciting Activities of the Japan Institute of Electronics Packaging (JIEP) and Expect the Valuable Actions for the Future!

I Trust the Exciting Activities of the Japan Institute of Electronics Packaging (JIEP) and Expect the Valuable Actions for the Future!

Nanosilica/recycled polycarbonate composites for electronic packaging

Several simple methods were performed to recycle compact discs (CDs) using an alkaline solution. The hydrophilic silica nanoparticles were incorporated into the recycled deinked polycarbonate CDs, and these particles affected the dielectric, structure, and thermal properties of the recycled polycarbonates. The thermal properties of recycled CDs were studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). No significant change in the thermal stability of polycarbonate/silica nanocomposites was observed with the mechanical /chemical modifications. X-ray diffraction (XRD) revealed the structural aspects, showing a correlation between crystallinity, silica nanoparticles, and modification methods. The mechanically treated sample after chemical handling had the lowest degree of crystallinity (48%), showing that the modification methods enhanced the formation of the amorphous state, thus affecting its dielectric properties. Scanning electron microscopy (SEM) characterized the CD samples' microstructure and morphology. Finally, the dielectric properties were studied using broadband dielectric spectroscopy (BDS) in the 101 - 106 Hz range. The samples prepared using chemical and mechanical treatments were of low dielectric loss. This increases its importance when such samples are used as antistatic charge materials. For these reasons, recycled PC/SiO2 nanocomposites are recommended as effective packaging materials for electronic components.

Enhanced thermal conductivity and insulating properties of PBO fiber grafted AlN/BN/PBO films for electronic packaging

Enhanced thermal conductivity and insulating properties of PBO fiber grafted AlN/BN/PBO films for electronic packaging

Innovative Wearable Electronics: Next-Generation Nitrogen-Doped Lutetium-Carbon Microspheres Composites for Robust Energy Harvesting.

In the quest to advance wearable electronics, this study presents a novel method using nitrogen-doped lutetium-carbon microspheres (N, Lu-CMS) for high-performance piezoelectric energy harvesting. The synthesis of N, Lu-CMS begins with the polymerization of sucrose, followed by the preparation of N, Lu-CMS metal complexes through the incorporation of lutetium (III) nitrate hydrate and thiourea, yielding a black powder product. The wearable electronic device is designed with a silicon rubber (SR) matrix, reinforced with 0D fillers such as N, Lu-CMS, or molybdenum disulfide (MoS₂). Mechanical testing revealed a significant improvement in compressive modulus, reaching 3.7MPa (N, Lu-CMS) at a concentration of 3 parts per hundred rubber (phr). Electromechanical assessments demonstrated efficient energy conversion, while biomechanical analysis, including thumb pressing tests, showed a notable increase in output voltage, peaking at ≈285mV (N, Lu-CMS) at 3 phr. This research provides a foundation for future engineering applications, particularly in electronic packaging for wearable electronics and smart devices, underscoring the significant impact of N, Lu-CMS in this emerging field. The surface power density achieved is 0.026 nWcm- 2 (N, Lu-CMS) and 0.0056 nWcm- 2 (Hybrid). Lastly, the conversion efficiency is 6.26% for N, Lu-CMS, and 1.05% for the hybrid system.

Paper waste and carbon emissions from oral contraceptive leaflets.

Oral contraceptives (OC) are the most used form of contraception among women in the U.S. and Europe. Like other medications, their packaging must include patient information leaflets. This study quantifies the environmental impact of paper waste generated by these leaflets. We conducted an observational analysis, measuring the weight of leaflets, pills, and packaging components across various OC brands. Significant variations in leaflet weights were observed. On average, leaflets accounted for 55% of the package weight, while pills and blister dispensers represented only 32%. The mean weight of OC leaflets was 12.3 ± 5.5 grams (4.7-21.9 grams), leading to an estimated annual paper waste of 6,118.4 tons, 5,763.5 tons of carbon dioxide equivalent emissions, and the use of approximately 146,841 trees for production. Standardizing leaflet weight to the lightest reported can reduce annual waste by 3780.5 tons of paper. This study highlights the substantial environmental cost of the waste generated from OC leaflets and proposes practical strategies to mitigate waste, including electronic leaflets and standardized packaging. Targeting these materials presents a significant opportunity to enhance sustainability, aligning with global efforts to reduce greenhouse gas emissions from the healthcare sector.

Toughening Mechanism of CaAl12O19 in Red Mud–Al2O3 Composite Ceramics

The utilization of red mud in the production of ceramic products represents an efficient approach for harnessing red mud resources. Composite ceramics were prepared from Al2O3, red mud, and Cr2O3 by atmospheric pressure sintering, and the phase composition and microscopic morphology of the composite ceramics were investigated by XRD, SEM, and EDS. The flexural strength and fracture toughness of composite ceramics were measured by three-point bending and SENB methods. The results showed that the composite ceramics sintered at 1500 °C with the addition of 1.5 wt.% Cr2O3 had a flexural strength of 297.03 MPa, a hardness of 17.44 GPa, and a densification of 97.75% and fracture toughness of 6.57 MPa·m1/2. The addition of Cr2O3 helps to improve the low strength of red mud composite ceramic samples. The CaAl12O19 phase can form a similar “endo-crystalline” structure with Al2O3 grains, which changes the fracture mode of the ceramics and thus significantly improves the fracture toughness. The wettability tests conducted on Cu and RM–Al2O3 composite ceramic materials revealed that the composites exhibited non-wetting behavior towards Cu at elevated temperatures, while no interfacial reactions or elemental diffusion were observed. Composites have higher surface energy than Al2O3 ceramic at high temperatures. The present study provides a crucial foundation for enhancing the comprehensive utilization value of red mud and the application of red mud ceramics in the field of electronic packaging.

Finite element analysis of 2.5D packaging processes based on multi-physics field coupling for predicting the reliability of IC components

The 2.5D packaging technology is a high–performance method for electronic packaging. This study addresses the reliability issues of 2.5D packaging during the manufacturing process. A multi–physics field coupling Finite Element Method (FEM) has been developed, combined with sub–modeling techniques, to investigate the curing of underfill adhesive, the curing of Epoxy Molding Compound (EMC), and the reflow soldering between the interposer and substrate in a 2.5D packaging entity during various manufacturing procedures. The focus is on the thermo–mechanical–chemical behavior of viscoelastic components within the packaging structure, as well as the viscoplastic characteristics of the micro solder balls and microbumps. A systematic analysis is conducted on the warpage deformation and stress distribution of the 2.5D packaging at crucial time points. The results demonstrate that after curing, the overall warpage of the packaging exhibits a ‘concave’ warpage profile. Additionally, as the thickness of the EMC above the chip increases, the warpage value of the packaging also increases. The warpage value defined by linear elasticity is larger than that defined by viscoelasticity. The maximum Von Mises stress value in the key areas of the submodel is greater than the maximum Von Mises stress value in the corresponding key areas of the global model. After reflow soldering, the stress concentration in the micro solder balls occurs at the edge of the micro solder ball array. The maximum stress values for each component of the packaging are observed in the interface areas between the components. Packaging components that undergo the curing process have notably higher warpage and Von Mises stress values than those that do not undergo the curing process. The simulation method established in this study can accurately predict the warpage deformation and stress distribution state of 2.5D packaging, providing significant engineering application value for process optimization and reliability enhancement of 2.5D packaging in the production process.

Electrochemical Migration Study on Sn-58Bi Lead-Free Solder Alloy Under Dust Contamination.

With the development of electronic packaging technology toward miniaturization, integration, and high reliability, the diameter and pitch of solder joints continue to shrink. Adjacent solder joints are highly susceptible to electrochemical migration (ECM) due to the synergistic effects of high-density electric fields, water vapor, and contaminants. Dust has become one of the non-negligible causal factors in ECM studies due to air pollution. In this study, 0.2 mM/L NaCl and Na2SO4 solutions were used to simulate soluble salt in dust, and the failure mechanism of an Sn-58Bi solder ECM in the soluble salt in dust was analyzed by a water-droplet experimental method. It was shown that the mean failure time of the ECM of an Sn-58Bi solder in an NaCl solution (53 s) was longer than that in an Na2SO4 solution (32 s) due to the difference in the anodic dissolution characteristics in the two soluble salt solutions. XPS analysis revealed that the dendrites produced by the ECM process were mainly composed of Sn, SnO, and SnO2, and there were precipitation products-Sn(OH)2 and Na2SO4-attached to the dendrites. The corrosion potential in the NaCl solution (-0.351 V) was higher than that in the Na2SO4 solution (-0.360 V), as shown by a polarization test, indicating that the Sn-58Bi solder had better corrosion resistance in the NaCl solution. Therefore, an Sn-58Bi solder has better resistance to electrochemical migration in an NaCl solution compared to an Na2SO4 solution.

Core-Shell Engineered Fillers Overcome the Electrical-Thermal Conductance Trade-Off.

The rapid development of modern electronic devices increasingly requires thermal management materials with controllable electrical properties, ranging from conductive and dielectric to insulating, to meet the needs of diverse applications. However, highly thermally conductive materials usually have a high electrical conductivity. Intrinsically highly thermally conductive, but electrically insulating materials are still limited to a few kinds of materials. To overcome the electrical-thermal conductance trade-off, here, we report a facile Pechini-based method to prepare multiple core (metal)/shell (metal oxide) engineered fillers, such as aluminum-oxide-coated and beryllium-oxide-coated Ag microspheres. In contrast to the previous in situ growth method which mainly focused on small-sized spheres with specific coating materials, our method combined with ultrafast joule heating treatment is more versatile and robust for varied-sized, especially large-sized core-shell fillers. Through size compounding, the as-synthesized core-shell-filled epoxy composites exhibit high isotropic thermal conductivity (∼3.8 W m-1 K-1) while maintaining high electrical resistivity (∼1012 Ω cm) and good flowability, showing better heat dissipation properties than commercial thermally conductive packaging materials. The successful preparation of these core-shell fillers endows thermally conductive composites with controlled electrical properties for emerging electronic package applications, as demonstrated in circuit board and battery thermal management.

Ag-Pd nanoalloy film with ultra-high thermal and electrochemical stability for power electronic packaging

Nano-Ag paste is a popular material in power electronic packaging, while its microstructure is unstable at high temperatures and suffers from electrochemical migration. In this work, Ag-Pd nanoalloy film has been prepared by the pulsed laser deposition, and been sintered at low temperature for packaging. The thermal stability is significantly improved at 300 ℃ when Ag is alloyed with Pd. The Pd addition significantly increased the diffusion activation energy of Ag atoms and reduced the diffusion coefficient. The Ag-Pd sintered layer exhibited a stable microstructure at 300 °C or even 500 °C, which indicated that Ag-Pd nanoalloy had the potential to serve at high temperatures. Ag-Pd nanoalloy will preferentially generate a PdO passivation film and cover the anode surface, thereby slowing down the dissolution of the Ag and improving its resistance to electrochemical migration. This work provides theoretical studies and insights into the applications of Ag-Pd nanoalloys in high-reliability power electronics.

Engineering designed functional covalent organic frameworks via pore surface modifications for effectively reducing the dielectric constant of polyimide-based electronic packaging materials

Polyimide (PI) is considered one of the most promising candidate materials for the microelectronics and wireless communication industries. Nevertheless, the relatively high dielectric constant of PI has become a significant obstacle, constraining its utilization in the realm of microelectronics. Herein, novel PI nanocomposite films were fabricated by incorporating covalent organic frameworks (COFs) and their functionalized counterparts (COF@POSS and COF@DTF) through post-synthetic modification. Among all PI nanocomposites films, PI/COF@POSS nanocomposite film including 2 wt% COF@POSS achieved the lowest dielectric constant (2.41) and dielectric loss (0.0076). These values represented a reduction of 22.5 % and 24 % compared to pure PI, respectively. The decrease in dielectric constant is ascribed to the combined influence of the porous structure of COF and the augmentation in free volume fraction caused by the steric hindrance of POSS. Additionally, the tensile strength of the PI/COF@POSS and PI/COF@DTF nanocomposite films increased up to 121.1 MPa and 112.0 MPa, representing a 95 % and 80 % improvement over pure PI, respectively. Furthermore, the introduction of COFs functionalized with POSS and DTF significantly enhanced the hydrophobicity of PI nanocomposite films. The combination of porous organic nanofillers with surface functionalization offers a feasible route to create low-k PI nanocomposite films with improved mechanical properties and hydrophobicity.

Ni mesh-reinforced ultrasonic-assisted Cu/Sn58Bi/Cu joint performance: Experiments and first-principles calculations

The Ni mesh was incorporated into the Cu/Sn58Bi/Cu bonding as a reinforcing skeleton to achieve an enhancement effect analogous to steel reinforcement in concrete. Ultrasonic-assisted soldering (UAS) improved the metallurgical bond among the solder, Ni mesh, and substrate. It facilitated the formation of (Cu, Ni)6Sn5 intermetallic compounds (IMCs) layers, increasing the joint strength. Observations indicated that ultrasonic treatment effectively refined the (Cu, Ni)6Sn5 grains and induced a uniform preferred orientation of β-Sn and Bi grains in the joint matrix adjacent to the Ni mesh. The shear strength of the joint reached 72.23 MPa when the ultrasonic application was sustained for 15 s, achieving the fabrication of a high-strength point with low energy consumption. First-principles calculations have confirmed that changes in the Ni content within (Cu, Ni)6Sn5 IMCs improved the stability of the crystal structure. Furthermore, the variations in content could potentially improve the mechanical and electrical properties of the (Cu, Ni)6Sn5. Enhancements in ultrasonic efficiency and the reinforcement of IMC structures offer new avenues for research in green and high-performance electronic packaging material joining technologies.