High-performance Packaging Research Articles

Research on the influence mechanism and modification technology of UV-curing adhesive on the HPLD thermal-induced misalignment

The demand for output performance and reliability of the HPLD (high-power laser diode) has become increasingly stringent with the development of application requirements. The thermal effect of the HPLD will lead to optical components' thermal-induced misalignment, which will significantly affect the output quality and power of the laser. In this paper, the influence of the thickness and uniformity of UV-curing adhesive on the thermal-induced misalignment of the bonding module is revealed. Then the thermal stability of UV-curing adhesive is optimized by the microparticles composite modification method. Finally, the single emitter array laser is packaged with the optimized modified UV-curing adhesive, the thermal-induced misalignment of beam-shaping components can be reduced by 8 times, and the power reduction ratio of the laser is reduced from 3.8% to 0.72%. This research supports efficient control of the thermal-induced misalignment which to ensures high-performance packaging and manufacturing for HPLD.

Microstructure and Shear Behaviour of Sn-3.0Ag-0.5Cu Composite Solder Pastes Enhanced by Epoxy Resin

With the rapid development of microelectronics packaging technology, the demand for high-performance packaging materials has further increased. This paper developed novel epoxy-containing Sn-3.0Ag-0.5Cu (SAC305-ER) composite solder pastes, and the effects of epoxy resin on their spreading performance, microstructure, and shear behaviour were analysed. The research results showed that with the addition of epoxy resin, SAC305 solder pastes exhibited exceptional spreadability on Cu substrates, which could be attributed to the reduction in the viscosity and the surface tension of the composite solder pastes. With the addition of epoxy resin, the solder matrix microstructure and interfacial morphology of SAC305-ER composite solder joints remained unchanged. However, continuous resin protective layers were observed on the surface of SAC305-ER composite solder joints after the reflow process. The shear properties of the composite solder joints were enhanced by the extra mechanical bonding effect provided by resin layers. When the epoxy resin content was 8 wt%, the shear forces of SAC305-ER composite solder joints reached the maximum value. Fracture analysis indicated that cracked epoxy resin was observed on the surface of SAC305-ER composite solder joints, indicating that the epoxy resin also underwent obvious deformation in the shear test.

Fabrication of high-performance 3D-interpenetrated network structures SiC/Al composites with SiC equiaxed grain frameworks

Electronic packaging materials should integrate with excellent overall performance including thermal, mechanical, and machinability to meet the challenges of the current highly integrated development of the electronics industry. The low-temperature sintering of high-strength 3D-SiC frameworks with equiaxed grains was achieved at 2250 °C by regulating the contents and particle size of coarse and fine powders in bimodal SiC hybrid particles. And 3D-interpenetrated network structures SiC/Al (SiC3D/Al) composites for electronic packaging were then fabricated using a vacuum/gas pressure infiltration Al alloys process. Results indicated the thermal conductivity (TC), coefficient of thermal expansion (CTE), and thermal deformation parameter (TDP) of the composites were improved with increasing coarse powder size. And SiC3D/Al with the coarse powder size of 38 μm and the coarse powder content of 60 wt% achieved the compatibility of optimal thermophysical and mechanical properties with flexural strength of 406.14 MPa, CTE of 5.38 × 10−6/K, TC of 230.03 W m−1 K−1, and TDP of 0.023 matching that of Si. A further increased coarse powder particle size to 48 μm and higher 58 μm reduced the mechanical properties by 14% and 22%, respectively. Moreover, the composites maintained stable CTE and TC after 100 thermal cycles, and 3D-SiC framework was free of defects and no interfacial debonding, ensuring long-term service reliability. Integration of distinguished overall performance was primarily implemented by the synergistic effect of the 3D network framework with equiaxed grains mutual strong bonding as well as the clean and well-bonded interface. This technology provides a reference for the design and synthesis of high-performance electronic packaging materials with scalability and tuneability.

Fabrication of cellulose/rectorite composite films for sustainable packaging

In order to reduce the environmental pollution caused by plastic packaging, the development of biodegradable high-performance packaging materials has become a research hotspot. Cellulose is a promising food packaging material, but it usually lacks sufficient ultraviolet (UV) shielding property and mechanical strength. In this work, rectorite microplates were incorporated into the cellulose matrix by a facile blending method to fabricate the composite films. The structure and properties of the composite films were characterized by FT-IR, X-ray diffraction, scanning electron microscopy, UV–vis and mechanical properties test etc. The results indicated that rectorite microplates were uniformly distributed in the cellulose matrix. The blocking percentages for UVA and UVB for the cellulose/rectorite composite film with 14 wt% rectorite content (RCRF-14) could reach as high as 97.8 % and 96.0 %, respectively, showing a good UV shielding property. Meanwhile, the addition of rectorite obviously improved the mechanical properties and decreased the water vapor and oxygen permeabilities of the cellulose film, showing a potential application as a sustainable food packaging material.

Design and synthesis of novel phenolphthalein-based poly (aryl ether) resin containing isopropyl groups

With the rapid development of 5G technology, low dielectric constant materials present a widespread application prospect in microelectronic devices. Poly (aryl ether) resins have been widely used in this field due to their excellent thermal stability, mechanical properties and electrical insulation properties, however, reducing its dielectric constant remains a challenge. In this study, novel phenolphthalein poly (aryl ether ketone) containing isopropyl groups and fluorene groups was successfully synthesized with high molecular weight via SN2 aromatic nucleophilic polycondensation reaction. At lower frequencies ranging from 10 Hz to 1 MHz and higher frequencies from 10 GHz to 42 GHz, the films exhibit the intrinsic dielectric constant in the range of 2.4–2.7. The resin has good thermal stability, mechanical properties and insulation properties. Thus, the functional poly (aryl ether ketone) possesses attractive potential applications in the field of high-performance flexible electronic packaging materials.

Graphitic surface layer formation on organic substrates for electronics using a concentrated solar simulator

Heat spreading is an important attribute that improves thermal management and operation of high-performance packages, such as those for solid-state power amplifiers. This attribute can be enhanced through direct transformation of polymers into graphitic films. The present work reports a custom vacuum deposition process that synthesizes thin graphitic layers on organic substrates through direct pyrolysis via concentrated irradiation from a xenon lamp to produce a peak heated zone of approximately 3 cm diameter with a maximum heat flux of 3.2 MW/m^2. The light source, replaceable with concentrated terrestrial solar power, provides ultrafast heating of substrates through rapid flashes (< 0.5 s) and improves growth rates over relatively larger areas compared to laser processing, mitigating the issue of porosity in graphitic layers that deteriorate heat spreading capabilities. The enhanced organic substrates are analyzed using Raman and energy-dispersive X-ray spectroscopy, scanning electron microscopy, and thermal diffusivity measurements, indicating graphitic conversion.Graphical abstract

Construction of MAPbBr3/EP composites with blocking path for high-performance gamma-rays shielding

As deep space exploration is getting further and further away, it is necessary to develop novel packaging shielding material with lightweight and high performance to improve the service life of spacecraft integrated circuits in space radiation environment. However, up to now, constructing a lightweight perovskite/epoxy composite packaging shielding material for spacecraft integrated circuits has not been reported. Hence, in this work, a novel MAPbBr3/epoxy (CH3NH3PbBr3/EP) composite is firstly reported, which shows excellent gamma-rays shielding performance with high linear attenuation coefficient (3.082 cm−1) and high mass attenuation coefficient (2.047 cm2/g). Radiation shielding mechanism indicates that gamma-rays mainly interact with MAPbBr3 dispersed in epoxy. In other words, MAPbBr3 forms a radiation blocking path in epoxy, which significantly attenuates the intensity of incident gamma-rays. In addition, MA+ in MAPbBr3 crystal structure effectively blocks the penetrating behavior of secondary electrons. This work provides a novel strategy for the design and synthesis of high-performance radiation shielding packaging materials.

Control of alignment of h-BN in polyetherimide composite by magnetic field and enhancement of its thermal conductivity

In this study, hexagonal boron nitride (h-BN) - polyetherimide (PEI) composites were prepared by a simple solution casting method, where the h-BN particles were aligned by an external magnetic field. Prior to the preparation of the composite samples, the h-BN platelets were firstly decorated by iron oxide nanoparticles (Fe 3 O 4 ) to achieve the desired magnetic properties. Due to the alignment of h-BN particles, the composite exhibited greatly enhanced thermal conductivity along that direction. At a filler loading of 20 wt%, an enhancement of 166% was obtained, compared to that of the unaligned composite. Furthermore, the composite samples showed a low dielectric loss (~ 0.01) with the filling ratio below 20 wt% and a tensile modulus of up to 2.34 GPa. Bearing such thermal conductivity, electrical insulation properties, and mechanical properties, these composites with magnetically aligned h-BN particles show potentials for microelectronic packaging applications. • h-BN were added into polyether imide (PEI) to prepare flexible composite films. • h-BN micro-platelets were aligned by an external magnetic field. • h-BN micro-platelets were firstly decorated by iron oxide nanoparticles to achieve magnetic properties. • The vertically aligned h-BN/PEI composite is promising for high-performance electronic packaging applications.

Improvement of trade-off between mechanical properties and dielectric of polyimide with surface modified silica nanoparticle for wafer level packaging

Recently, as 3-D stacking and high integration are required in semiconductor packaging technology, it is critical to develop higher performance packaging materials. Insulation ability and mechanical properties of passivation layer should be enhanced to prevent device from electrical short and malfunction. In this study, low dielectric, residual stress, and the coefficient of thermal expansion polyimide/surface modified silica nanoparticle composites for wafer level packaging are synthesized and investigated. Silica nanoparticles of which surface modified with amine functional group increased the distance between polymer chains to form a free space, thereby lowering the dielectric constant. Also, they acted as a cross-linker and showed the effect of improving the mechanical properties of polyimide. Consequently, synthesized composites are potential candidate for high performance packaging material.

PACKAGE-ON-PACKAGE (POP) UNDERFILL PROCESS USING A MATERIAL DAM METHOD

Recent developments in the electronics industry have introduced a multi-stack ball grid array (BGA) to meet the growing consumer demand for both high-performance and smaller-sized chip packages. This study focused on the preliminary study of the Package-on-Package (PoP) underfill process using a material dam method. High viscosity type of underfill material is considered for the underfill process. In the current experimental work, L path-dispensing method was chosen due to its advantages, as reported in the previous work. The material dam method was used to prevent underfill from moving backwards and flowing out from the dispensing region. The material dam was built surrounding the PoP package. The effectiveness of the underfill process was analyzed based on the cycle time and lateral lapping, which are significant factors in material selection. The experimental results revealed that slow underfill flow may cause the quickly harden of material while the dispensing process is still running. This situation restricts the underfill flow and creates voids in the PoP package. The material dam method successfully enhanced the underfilling process for layers 3 and 4 stacked-package. This study is expected to provide the preliminary underfill process of stacking the PoP package and is useful as a reference for the engineer in the microelectronics industry.

Lignocellulosic nanofibrils as multifunctional component for high-performance packaging applications

Polyvinyl alcohol (PVA), a biodegradable polymer, has emerged as a promising alternative to non-biodegradable petrochemical counterparts to reduce the environmental impact of the food and medical industries. In this study, we demonstrate an environmentally friendly and low-cost strategy to broaden the application scope of PVA as a packaging material by enhancing the polymer mechanical performance and reducing its hydrophilicity. By taking advantage of hydrophobic lignin that is covalently bound to the mechanically strong cellulose nanofibrils, we demonstrated that integrating oxidized lignocellulosic nanofibrils (t-LCNF) in PVA enhanced the mechanical properties, water barrier performance, and thermal stability. With only 2 wt% t-LCNF, remarkable improvements in tensile strength (21%) and toughness (74%) were obtained compared to pristine PVA films. In addition, the integration of t-LCNF improved PVA thermal stability (+67 °C at 20 wt% t-LCNF), water barrier property (−0.67 g/(m2 *day)*m in water vapor transmission rate at 10 wt% t-LCNF), hydrophobicity (contact angle of 97.3° at 20 wt% t-LCNF), and provided tunable UV-shielding properties. This study demonstrated the excellent promise of t-LCNF as a low-cost and multifunctional component that enhances the properties of PVA for packaging applications.

High-performance multifunctional polyvinyl alcohol/starch based active packaging films compatibilized with bioinspired polydopamine nanoparticles

Bioinspired polydopamine (PDA) nanoparticles were synthesized and explored as functional compatibilizers in polyvinyl alcohol/starch (PVA/ST) matrix to develop high-performance multifunctional packaging film. The effect of the addition of PDA on the microstructural, mechanical, thermal, water vapor barrier, ultraviolet (UV)/high-energy blue light (HEBL) blocking, thermal insulating and antioxidant properties of PVA/ST composite films was fully investigated. Results demonstrated that the added PDA nanoparticles were evenly dispersed in the PVA/ST matrix, providing compact and dense nanocomposite films due to their compatibilization effect. Compared with virgin PVA/ST film, the resulting PVA/ST/PDA nanocomposite films exhibited greatly improved tensile strength, toughness, thermal stability, and water vapor barrier ability. Furthermore, the presence of PDA endowed PVA/ST composite film with excellent UV/HEBL blocking, thermal insulating as well as antioxidant functions. Thus, such high-performance multifunctional nanocomposite films hold the potential of protecting food quality against photothermal oxidative deterioration and extend food shelf life.

Epoxy-based siloxane composites for electronic packaging: Effect of composition and molecular structure of siloxane matrix on their properties

Epoxy-based composites are widely used in electronic packaging because of their excellent moldability and insulation properties. However, commercial epoxy-based materials have low thermal stability and high thermal expansion. Herein, we report epoxy siloxane/silica composites that improve the thermal, mechanical, and insulating properties of epoxy resin by introducing a sol–gel-synthesized siloxane hybrid and silica particles. We develop two types of epoxy-based composites with different siloxane molecular structures (branch and linear) and investigate the changes in their properties with different compositions and siloxane structures. Branched siloxane structure leads to hard and low insulating properties, whereas linear siloxane structure results in soft and high insulating properties. Both epoxy siloxane/silica composites exhibit high thermal stability and low thermal expansion. These properties are greatly improved by the incorporation of silica particles. Finally, we confirm the feasibility of the use of developed composites in electronic packaging, wherein two types of epoxy-based siloxane/silica composites are coated onto a commercial metallic substrate without any deformation. Our epoxy-based composites have significant potential as high-performance and robust electronic packaging materials. In addition, our composite-design approach can easily control the composite characteristics of mechanics and insulation, and improve both these properties by employing silica particles with a homogeneous distribution.

Cyanate ester resins containing Si-O-C hyperbranched polysiloxane with favorable curing processability and toughness for electronic packaging

High-performance electronic packaging materials with favorable processability are highly desirable to satisfy the booming of new generation communication technology. Herein, the bisphenol A cyanate ester (BADCy) resins containing Si-O-C hyperbranched polysiloxane were fabricated with facile curing process to achieve the application of electronic packaging. The fabricated BADCy resins exhibited not only significantly reduced curing temperature in favor of facile processability, but also dramatically enhanced toughness for prolonging the service life of packaging materials. The curing peak temperature was miraculously decreased by 93.5 °C. Meanwhile, the impact strength was significantly enhanced by 105.3%. Notably, the BADCy resins presented lower dielectric constant (ε of 2.59) and dielectric loss tangent values (tan δ of 0.0062) at 10 GHz. The results suggest that HSiEP possesses promising potential applications in the field of electronic packaging.

Low Thermal Conductivity Adhesive as a Key Enabler for Compact, Low-Cost Packaging for Metal-Oxide Gas Sensors

Metal-oxide (MOX) gas sensors commonly rely on custom packaging solution. With an ever-increasing demand for MOX gas sensors, there is a clear need for a low cost, compact and high-performance package. During normal operation, MOX sensors are heated up to a temperature in the typical range of 200-300°C. However, the generated heat must not damage or degrade any other part of the assembly. Using 3D finite elements modelling, we developed an optimal package configuration. To thermally insulate the assembly from the heated MOX sensor we have developed in-house a low thermal conductivity xerogel-epoxy composite with 22.7% by weight xerogel and a thermal conductivity of 107.9 mW m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> K <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> which is a reduction exceeding 30% compared to commercially available epoxy. Based on the low thermal conductivity xerogel-epoxy composite, we have developed a novel packaging approach that can suit the large family of MOX sensors. The developed alternative packaging solution includes a small number of assembly steps and uses standard processes and techniques. The assembled MOX sensor is low cost and has a low power consumption, while all thermally sensitive assembly parts remain at low temperature during the system’s lifetime.

Lignocellulosic Nanofibrils as Multifunctional Component for High-Performance Packaging Applications

Lignocellulosic Nanofibrils as Multifunctional Component for High-Performance Packaging Applications

Synthesis and properties of low dielectric constant phenolphthalein-based poly (aryl ether) resin containing isopropyl groups

In this study, a novel phenolphthalein poly (ether nitrile) containing isopropyl groups (iPrPENC) was successfully synthesized via SN2 aromatic nucleophilic polycondensation. The flexible and tough iPrPENC films exhibited an intrinsic low dielectric constant value of 2.86 at the frequency of 1 MHz. The resin has good thermal stability and mechanical property. In addition, it can be dissolved in common organic solvents. Thus, the functional poly (aryl ether nitrile) possessed attractive potential applications in the field of high-performance flexible electronic packaging materials.

A Review on the Fabrication and Reliability of Three-Dimensional Integration Technologies for Microelectronic Packaging: Through-Si-via and Solder Bumping Process

With the continuous miniaturization of electronic devices and the upcoming new technologies such as Artificial Intelligence (AI), Internet of Things (IoT), fifth-generation cellular networks (5G), etc., the electronics industry is achieving high-speed, high-performance, and high-density electronic packaging. Three-dimensional (3D) Si-chip stacking using through-Si-via (TSV) and solder bumping processes are the key interconnection technologies that satisfy the former requirements and receive the most attention from the electronic industries. This review mainly includes two directions to get a precise understanding, such as the TSV filling and solder bumping, and explores their reliability aspects. TSV filling addresses the DRIE (deep reactive ion etching) process, including the coating of functional layers on the TSV wall such as an insulating layer, adhesion layer, and seed layer, and TSV filling with molten solder. Solder bumping processes such as electroplating, solder ball bumping, paste printing, and solder injection on a Cu pillar are discussed. In the reliability part for TSV and solder bumping, the fabrication defects, internal stresses, intermetallic compounds, and shear strength are reviewed. These studies aimed to achieve a robust 3D integration technology effectively for future high-density electronics packaging.

Tuning the microstructure and enhancing the mechanical properties of Au-20Sn/Au/Ni(P)/Kovar joint by ultrasonic-assisted soldering method

Improving the reliability of the solder joint has been the recent research focus in the electronic packaging field due to the increasing degree of integration in the electronic devices. During the reflow soldering process, when the local component is heterogeneous, the coarse structure of the solder joint is easy to grow, which deteriorates the performance of the solder joint. In this study, Au-20Sn/Au/Ni(P)/Kovar joints were prepared using ultrasonic-assisted reflow soldering process. Ultrasonication during reflow improved the wettability and shear strength between the Au-20Sn solder and Kovar substrate. The applied ultrasound can break the primary Au 5 Sn grain and refine the eutectic microstructure through acoustic cavitation. Meanwhile, ultrasound induced the formation of a new intermetallic compound (IMC) layer that was identified as Ni 3 P ( ca 120 nm), which inhibited the diffusion of Ni from substrate into the solder matrix. The mechanical properties of Au-20Sn/Au/Ni(P)/Kovar joint treated with 80 W ultrasonic vibration (USV) increased by 46.94% as compared to the control sample. The current study provides a new strategy for high-performance packaging in electronic devices in extreme environments.

PeriPy - A high performance OpenCL peridynamics package

This paper presents a lightweight, open-source and high-performance python package for solving peridynamics problems in solid mechanics. The development of this solver is motivated by the need for fast analysis tools to achieve the large number of simulations required for ‘outer-loop’ applications, including sensitivity analysis, uncertainty quantification and optimisation. Our python software toolbox utilises the heterogeneous nature of OpenCL so that it can be executed on any platform with CPU or GPU cores. We illustrate the package use through a range of industrially motivated examples, which should enable other researchers to build on and extend the solver for use in their own applications. Step improvements in execution speed and functionality over existing techniques are presented. A comparison between this solver and an existing OpenCL implementation in the literature is presented, tested on benchmarks with hundreds of thousands to tens of millions of nodes. We demonstrate the scalability of the solver on the GeForce RTX 2080 TiGPU from NVIDIA, and the memory-bound limitations are analysed. In all test cases, the implementation is between 1.4 and 10.0 times faster than a similar existing GPU implementation in the literature. In particular, this improvement has been achieved by utilising local memory on the GPU.