Electronic Packaging Substrate Research Articles

Phosphononitrile based bismaleimide electronic packaging substrate with both fire safety and dielectric properties: Assisting 5G communication

Due to the high polarizability of traditional flame retardants, it is difficult to meet the excellent dielectric properties and flame retardancy required for electronic packaging materials. Therefore, we have designed a novel linear polyphosphazene that can balance the dielectric properties and flame retardancy of bismaleimide (BMI) composites. Here, fluorinated aromatic ring structure with the large freedom volume is connected to the main chain of polydichlorophosphazene (PDCP) as a side group, resulting in multifunctional fluorinated linear polyphosphazene (PBTFP). Attributed to the excellent P/N/F combination flame retardant strategy, extremely low polarizability, and large molecular free volume, PBTFP simultaneously improves the dielectric properties and flame retardancy of the BMI composites, including UL-94 rating of V0, and a dielectric constant (Dk) as low as 2.69. In addition, as an elastomer, PBTFP exhibits positive effects on improving the hydrophobicity and toughness of BMI. Therefore, through a simple affinity substitution reaction, we prepared a multifunctional fluorinated linear polyphosphazene modified BMI based electronic packaging substrate material that can be applied to 5G high-frequency communication.

Viscoelastic behaviour of poly(ether-ketone)/fly ash composites fabricated by powder metallurgical route

Poly(ether-ketone)/fly ash (FA) composites reinforced with 0-30 wt% FA were fabricated using ball milling followed by hot compaction. The composites were investigated for mechanical and viscoelastic properties. Scanning electron microscopy revealed excellent dispersion and good adhesion of FA particles with the matrix. The addition of FA increased the microhardness by 70% and the storage modulus (below glass transition) by 75%. The reinforcing efficiency was better above the glass transition, which increased to around 177% at 250°C. This research indicates that the FA can be used as an alternative reinforcement of costly ceramic powder for the electronic packaging substrate or printed circuit board applications.

Interface reaction and intermetallic compound growth behavior of Sn-Ag-Cu lead-free solder joints on different substrates in electronic packaging

During soldering and service, intermetallic compounds (IMCs) have an important impact on the performance and reliability of electronic products. A thin and continuous intermetallic layer facilitates the formation of reliable solder joints and improves the creep and fatigue resistance of solder joints. However, if the IMCs overgrow, the coarse IMC becomes brittle and tends to crack under stress, leading to a decrease in solder joint reliability. Based on the latest developments in the field of lead-free solders at home and abroad, this paper comprehensively reviews the interfacial reaction between SnAgCu Pb-free solders and different substrates and the growth behavior of IMCs and clarifies the growth mechanism of interfacial IMCs. The effects of the modification measures of lead-free solder on the IMCs and reliability of SnAgCu/substrate interface are analyzed, which provide a theoretical basis for the development and application of new lead-free solder.

Fluid flow and heat transfer characteristics of liquid cooling microchannels in LTCC multilayered packaging substrate

The fluid flow and heat transfer of liquid cooling microchannels embedded in low temperature co-fired ceramic (LTCC) multilayered electronic packaging substrate have been investigated. Four cooling systems were supplied for high power application of 100W LED lamp, including aluminum finned heat sink and LTCC substrates with parallel, serpentine and spiral microchannels. The pressure, flow rate, Reynolds number, fiction factor, Poiseuille number and Nusselt number were experimentally measured and theoretically analyzed. The heat transfer behaviors characterized by the drop of maximum working temperature and temperature distribution were measured by a thermal video system based on infrared thermometry. The microstructure and roughness of microchannel were studied by using Scanning Electron Microscope and Tribo Indenter. The measured flow rate of parallel microchannel under the same inlet pressure was much higher than those of serpentine and spiral microchannels. A linear dependence of Nusselt number on Reynolds number was observed and conformed to the convective heat transfer mechanism in microchannel. The parallel microchannel was found to have the best heat transfer performance and reduced the maximum working temperature to 99.52°C, much lower than those of other cooling systems. The temperature distribution of LED lamp was also significantly improved by the internal parallel liquid cooling microchannel in LTCC substrate.

Dielectric Properties and Microstructure of BaO-Nd<sub>2</sub>O<sub>3</sub>-Bi<sub>2</sub>O<sub>3</sub>-TiO<sub>2</sub> Microwave Ceramics with Li<sub>2</sub>O-B<sub>2</sub>O<sub>3</sub>-SiO<sub>2</sub>

Low temperature co-fired ceramics (LTCC) technology becomes crucial in the development of various modules and substrates in electronic packaging, especially in wireless and microwave applications [. With this technology, passive components (such as capacitors and inductors) can be embedded into substrates, and co-fired with high-conductive metals (such as silver and copper) below 900°C. Therefore, the shringkage and dielectric properties of LTCC are of great importance to the performance of components. So far, ceramic/glass composites have been widely researched for LTCC application due to tailored physical properties and low sintering temperature [2-3].

Improvement in the Low-Fire Dielectric Compositions with Middle Permittivity for LTCC Applications

Low temperature co-fired ceramics (LTCC) technology becomes crucial in the development of various modules and substrates in electronic packaging, especially in wireless and microwave applications [. self-integrated component has laid basis on flexibility of design, wiring density and dependability for multilayer structures due to LTCC technology. Recently, with the rapid progress in wireless communications,to realize more highly integrated passive components in multilayer LTCC structure, however, it is important to control the matching behavior between component and substrate. The dielectric compositions the permittivity range of which is 20100 are most appropriate for realizing strip or microstrip resonator structures in LTCC multilayer structures due to the RF frequency range which is used in current telecommunication systems (130GHz) and the desirable chip sizes in the current technologies (210 mm)[.

High performance polymer/AlN composites for electronic substrate application

An ideal high performance poly(etheretherketone) (PEEK)/AlN composite that has unique combination of anisotropic linear coefficient of thermal expansion (CTE) and dielectric properties was developed for the use in electronic packaging substrate as an alternative of conventionally used epoxy/E-glass substrate. The out-of-plane and in-plane CTEs of the composites were very close to that of copper and silicon chip, respectively. The dielectric constants of the composites are almost independent with increasing frequency. The dissipation factor decreased approximately 50% compared to the pure PEEK. These results reveal that the composite may be the futuristic candidate for high performance electronic packaging substrate.

Role of interface on dynamic modulus of high‐performance poly(etheretherketone)/ceramic composites

AbstractHigh‐performance printed circuit board or electronic packaging substrate with low warping particularly at high frequency is the key demand of manufacturers. In the present work, poly(etheretherketone) (PEEK) matrix composites reinforced with untreated micron size aluminum nitride (AlN) and alumina (Al2O3) particles have been studied for dynamic modulus in the temperature range varying from 30 to 250°C. At 48 vol % particles, the room temperature modulus of the PEEK/AlN composites increased by approximately fivefold (∼ 23 GPa), whereas it increased by twofold for PEEK/Al2O3 composite. The reinforcing efficiency is more pronounced at higher temperatures. The significant improvement in modulus was attributed to the better adhesion between the matrix and the AlN particles. Scanning electron microscope (SEM) and Kubat parameter showed that the poor adhesion between the matrix and the Al2O3 particles resulted in comparatively smaller increase in modulus of PEEK/Al2O3, despite higher intrinsic modulus of Al2O3 than that of AlN. SEM showed almost uniform distribution of particles in the matrix. The experimental data were correlated with several theoretical models. The Halpin–Tsai model with ξ (xi) is equal to four correlates well up to 48 vol % AlN composites while ξ is equal to two correlates only up to 18 vol % Al2O3 composites. Guth–Smallwood model also correlates well up to 28 vol % AlN and 18 vol % Al2O3‐filled composites. Thereafter, data deviated from it due to the particles tendency to aggregate formation. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Thermal expansion of a novel hybrid SiC foam–SiC particles–Al composites

A new type of hybrid SiC foam–SiC particles–Al composites ( V SiC = 53, 56.2 and 59.9%) to be used as an electronic packaging substrate material were fabricated by squeeze casting technique, and their thermal expansion behavior was evaluated. The coefficients of thermal expansion (CTEs) of the hybrid composites in the range of 20–100 °C were found to be between 6.6 and 7.7 ppm/°C. The measured CTEs are much lower than those of SiC particle-reinforced aluminum (SiC p–Al) composites with the same content of SiC because of the characteristic interpenetrating structure of the hybrid composites. A material of such a low CTE is ideal for electronic packaging because of the low thermal mismatch (and therefore, low thermal stresses) between the electronic component and the substrate. To achieve similar CTEs in SiC p–Al composites, the volume fraction of SiC would be much higher than that in the hybrid composites.

Processing aspects of glass-nicalon fibre and interconnected porous aluminium nitride ceramic and glass composites

Glass matrix-fibre and glass infiltrated ceramic composites with interconnected phases have been shown to have the potential for displaying optimum thermal conductivity and dielectric constant at 1 MHz making them useful as substrates for electronic packaging. Ceramic (Nicalon and silicon carbide grade (SCS)) fibre-borosilicate glass composites were fabricated using tape casting processes combined with pressure and pressureless sintering techniques. Experiments were also conducted to process AIN ceramics with interconnected porous channels which were then hot infiltrated with borosilicate glass. Results of optical characterization of the composites indicate that infiltration of Nicalon cloth with glass is achieved by hot pressing, while the tape casting and lamination approach followed by sintering is useful for fabricating composites of glass and Nicalon tows. The sintered aluminium nitride ceramics are comprised of ≈28% (volume fraction) interconnected pores. Hot infiltration yielded ≈100 μm penetration of borosilicate glass into the pores of the nitride ceramic. The paper discusses the various scientific aspects involved in processing the glass-fibre and porous AIN composites containing 3-d interconnected pores. Results of the microstructural characterization of these composites are discussed particularly in regards to the desired microstructure essential for these composites to be useful as substrates in electronic packaging.

Novel low-temperature synthesis of glasses and glass-ceramics in the B2O3-SiO2-P2O5 system

In recent years considerable progress has been made in electronic packaging substrate technology. The future need of miniaturization of devices to increase the signal processing speed calls for an increase in the device density requiring the substrates to be designed for better thermal, mechanical and electrical efficiency. Fast signal propagation with minimum delay requires the substrate to possess very low dielectric constant. Several glasses and glassceramic materials have been identified over the years which show good promise as candidate substrate materials. Among these, borophosphate and borophosphosilicate glass-ceramics have been recently identified to have the lowest dielectric constant (3.8). Sol-gel processing has been used to synthesize borosilicate, borophosphosilicate and borophosphate glasses and glass-ceramics using inexpensive boron oxide and phosphorus pentoxide precursors. Preliminary results of the processing of these gels and the effect of volatility of boron alkoxide and its modification on the gel structure are described. X-ray diffraction, differential thermal analysis and Fourier transform-infrared spectroscopy have been used to characterize the as-as-prepared and heat-treated gels.

Sol-Gel Processing of Glasses and Glass-Ceramics for Microelectronic Packaging

In recent years considerable progress has been made in electronic packaging substrate technology. The future need of miniaturization of devices to increase the signal processing speeds calls for an increase in the device density requiring the substrates to be designed for better thermal, mechanical and electrical efficiency.Fast signal propagation with minimum delay requires the substrate to possess very low dielectric constant. Several glasses and glass-ceramic materials have been identified over the years which show good promise as candidate substrate materials. Among these borophosphate and borophosphosilicate glass-ceramics have been recently identified to have the lowest dielectric constant (3.8). Sol-gel processing has been used to synthesize borosilicate, borophosphosilicate and borophosphate glasses and glass-ceramics using inexpensive boron oxide and phosphorus pentoxide precursors. Preliminary results of the processing of these gels and the effect of volatility of boron alkoxide and its modification on the gel structure are described. X-ray diffraction, Differential thermal analyses and FTIR have been used to characterize the as-prepared and heat treated gels.