Printed Circuit Board Applications Research Articles

Mechanistic insight into the Janus Green B on electrochemical roughening layer of copper foil

This study explores the impact of the electroplating additive JGB the surface characteristics and peel strength of electrolytic copper foils used in printed circuit boards. Utilizing Scanning Electron Microscopy and Atomic Force Microscopy, we found that optimal JGB concentrations enhance the morphology and roughness of the copper foil roughening layer while maintaining high peel strength. The ideal concentration of 3 mg/L achieved an average roughness of 0.953 µm and a peel strength of 0.946 N/mm. JGB's effectiveness in inhibiting copper deposition was confirmed through cyclic voltammetry, linear sweep voltammetry, and electrochemical impedance spectroscopy. Density Functional Theory calculations and in situ infrared spectroscopy elucidated JGB's adsorption and coordination actions, which have a synergistic effect on its inhibitory performance. Further investigations with molecular dynamics simulations and finite element analysis demonstrated JGB's preferential adsorption in areas of high electric field intensity, effectively controlling the copper grain morphology in the roughening layer. This research highlights the potential of dye-type additives in improving copper foil roughening for printed circuit boards applications. Future research should explore the long-term stability and environmental impact of JGB in industrial applications, while investigating other dye-type additives may further optimize the roughening process to meet diverse printed circuit boards manufacturing needs.

Durability of Lead-Free Solder Interconnections for Printed Circuit Board Applications: Comparing Energy-Based Thermo-Mechanical Fatigue Models

Fatigue models for predicting the cycles to failure of solder interconnections under temperature cycling situations have been discussed and developed for decades. However, most models were developed for different solder materials, components, and printed circuit boards. No previous work has systematically compared these models. Therefore, the variability of their durability predictions is unknown. This study compared nine existing low-cycle energy-based fatigue models for different solder materials and components and then analyzed the differences among them. Each fatigue model had a specific combination of the factors that affect the strain energy density accumulation. Therefore, we adjusted the strain energy density (input) and the predicted cycles to failure (output) in a consistent way to compare the selected fatigue models on the same basis. The differences among the predictions on cycles to failure from the fatigue models was significantly reduced after applying the adjustments, and they exhibited excellent consistency around 1 mJ/mm 3 strain energy density. In the end, factors that can affect the prediction consistency of fatigue mode were provided, including the number of data points while building the fatigue model, the range of strain energy density while selecting the electronic components, and the application of volume-weighted averaging technique on the critical solder joint.

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.

Preparation of Biobased Printed Circuit Board Prototypes Using Poly(furfuryl alcohol) Resin

The present study explores the processability and properties of poly(furfuryl alcohol) (PFA)-based composites and draws comparisons with the industry-standard epoxy resin matrices used in printed circuit board applications. A poly(furfuryl alcohol)-based fiberglass prepreg was used to manufacture composite cores laminated with copper foil, which were then integrated in situ into printed circuit board prototypes through industry-typical manufacturing and assembly processes. Both copper cores and printed boards were tested to characterize the electrical properties and overall quality of the prototypes. The fabrication of the copper cores and manufacturing methods of the printed boards are described, alongside the results from the characterization of the cores and the testing of the printed boards. The inherent advantages and disadvantages of the material are highlighted, and areas of improvement for the processability of the material and reliability of the technology are discussed.

Development of banana fabric incorporated polymer composites for printed circuit board application

Development of banana fabric incorporated polymer composites for printed circuit board application

Low Dielectric Constant Characteristics of Styrene and Maleimide Anhydride Copolymer with Modification for High Frequency Application of Printed Circuit Board.

Recently, due to the intensive and fast progress of the high frequency wireless communication environment, including 5th generation (5G) wireless communication, more robust substrate for printed circuit board (PCB) application, especially with less power consumption, is required. In this study, modified resins based on styrene-maleic anhydride (SMA) copolymer were prepared and evaluated as binder resin to accomplish a low dielectric constant or relative permittivity (εr: <3.0) substrate for the PCB application under ultrahigh frequencies (UHF; 1 GHz~9.4 GHz). The low εr dielectric characteristics of the modified SMA copolymer could be correlated with effects from the stereo-structure of carbon chains or conformational orientation, where the degree of crystallization was analyzed by X-ray diffraction (XRD) and nuclear magnetic resonance (NMR) spectroscopies. Prepreg films of the low εr modified SMA copolymers and their compounds with epoxy resins were also characterized in terms of dielectric loss or dissipation factor (Df), which have shown more noticeable relation with their stereo-structures as well.

Novel, Simple, and Green Citrate-Based Copper Electronic Electroplating Bath in Microvia Void-Free Filling for Printed Circuit Board Application

In this work, a novel, simple, and green citrate-based copper electronic electroplating bath with the characteristics of weak corrosion, low copper ion concentration, and simple composition is developed in microvia void-free filling for printed circuit board application. Succinimide (SM), regarded as a leveler, is the core component of the bath. The action mechanisms of SM on microvia void-free copper filling are carefully expounded. UV–vis spectroscopy and theoretical calculations demonstrate that only the [Cu2(Cit)2]2– coordination ion exists in the bath containing SM at pH 9.0. Linear sweep voltammetry and in situ Fourier transform infrared spectroscopy combined with X-ray photoelectron spectroscopy experiments illustrate that SM can inhibit the electroreduction of the [Cu2(Cit)2]2– coordination ion and promote the electroreduction of intermediate Cu(I) to Cu(0), resulting in the improvement of coating quality. Galvanostatic measurements reveal that the reduction of the [Cu2(Cit)2]2– coordination ion is electrochemically controlled, and SM is diffusion-controlled. The leveler properties of SM (diffusion control and inhibition of [Cu2(Cit)2]2– coordination ion electroreduction) promote copper in bottom-up growing and void-free filling of microvias.

Electrochemical and in situ FTIR spectroscopic studies of gentian violet as a novel leveler in through-holes metallization for printed circuit board applications

An organic additive, gentian violet (GVT), is explored for the first time as a novel leveler with excellent property in through-holes (THs) metallization of Cu electronic plating in acidic medium for printed circuit board (PCB) applications. Studies of galvanostatic measurements with a platinum rotation disk electrode and density functional theory calculations demonstrate that the GVT behaves the fundamental leveler's characteristics of mass transfer adsorption, and displays a strong inhibition effect on electro-reduction of cupric ions at high rotating rate. Although the adsorption ability of GVT on Cu surface is weaker than that of commercial leveler Janus Green B (JGB), the potential difference of cupric ion reduction between low and high rotating rates is larger in case of GVT than that of JGB at same current density. Cyclic voltammetry measurements indicate that the Cu amounts of cathodic deposition and that of anodic stripping tend to the same at both low and high rotating rates when GVT, Cl−, polyethylene glycol (PEG) and bis-(sodium sulfopropyl)-disulfide (SPS) coexist in the solution, demonstrating excellent synergistic action of these additives and super leveling effect. In situ FTIR spectroscopic analysis combined with cyclic voltammetry measurements illustrate that the GVT adsorbs on Cu surface and thus affects the electro-reduction of cupric ions, which reveals the very complicated synergistic actions of these additives, i.e., the adsorption ability of GVT can be slightly enhanced by Cl−, while it has been greatly enhanced in the presence of PEG which nevertheless decreases slightly the inhibition effect of PEG on electro-reduction of cupric ions; the SPS plays an antagonistic effect with GVT due to their competitive adsorption. Based on the characterization of GVT as a novel leveler, we developed a GVT-based formula of THs metallization of Cu electronic plating, and demonstrated an excellent efficiency of a throwing power of 97.6% at 10 mA·cm−2 in a real PCB THs metallization of Cu electronic plating.

Poly(ether-ketone) (PEK)/ceramic nanocomposites as alternate materials for printed circuit board application

ABSTRACT Poly(ether-ketone) (PEK)/silicon nitride (Si3N4) nanocomposites were fabricated by cold compaction followed by sintering at 260°C. Vickers microhardness and storage modulus of the nanocomposites increased, while their % crystallinity and thermal stability decreased without affecting the glass transition temperature. The dielectric constant of the nanocomposites increased to 5.03 with a dissipation factor (at 1 kHz) below 0.007. In brief, the PEK/Si3N4 nanocomposites might be useful as potential candidates as alternative material for the printed circuit board application.

Bioplastics and Carbon-Based Sustainable Materials, Components, and Devices: Toward Green Electronics.

The continuously growing number of short-life electronics equipment inherently results in a massive amount of problematic waste, which poses risks of environmental pollution, endangers human health, and causes socioeconomic problems. Hence, to mitigate these negative impacts, it is our common interest to substitute conventional materials (polymers and metals) used in electronics devices with their environmentally benign renewable counterparts, wherever possible, while considering the aspects of functionality, manufacturability, and cost. To support such an effort, in this study, we explore the use of biodegradable bioplastics, such as polylactic acid (PLA), its blends with polyhydroxybutyrate (PHB) and composites with pyrolyzed lignin (PL), and multiwalled carbon nanotubes (MWCNTs), in conjunction with processes typical in the fabrication of electronics components, including plasma treatment, dip coating, inkjet and screen printing, as well as hot mixing, extrusion, and molding. We show that after a short argon plasma treatment of the surface of hot-blown PLA-PHB blend films, percolating networks of single-walled carbon nanotubes (SWCNTs) having sheet resistance well below 1 kΩ/□ can be deposited by dip coating to make electrode plates of capacitive touch sensors. We also demonstrate that the bioplastic films, as flexible dielectric substrates, are suitable for depositing conductive micropatterns of SWCNTs and Ag (1 kΩ/□ and 1 Ω/□, respectively) by means of inkjet and screen printing, with potential in printed circuit board applications. In addition, we exemplify compounded and molded composites of PLA with PL and MWCNTs as excellent candidates for electromagnetic interference shielding materials in the K-band radio frequencies (18.0–26.5 GHz) with shielding effectiveness of up to 40 and 46 dB, respectively.

Interfacial polarization effects on dielectric properties in flax reinforced polypropylene/strontium titanate composites

Interfacial polarization or Maxwell-Wagner-Sillars effect using a dielectric study with the addition of strontium titanate and flax fiber reinforcement on a polypropylene matrix were investigated. Scanning electron microscopy (SEM) was performed for characterizing the fabricated sample to identify its fibers, ceramic, and polymer matrix regions. In the presence of strontium titanate and flax fiber reinforcement, the SEM images show signs of small ceramic agglomerates with fewer voids on fiber surfaces and a homogeneous distribution of fillers in the polymer matrix. The dielectric measurements revealed that dielectric relaxation occurs at low temperatures. The interfacial polarization was modeled using the Havriliak-Negami function, whereas the theoretical calculation shows a good best fit line with the experimental ones. The interfacial relaxation strength showed an increase of 202.54% from neat polypropylene matrix to flax reinforced polypropylene-strontium titanate composite from 0.866 to 2.62, respectively. This increase in dielectric strength is attributed to the accumulation of charge carriers at polypropylene-flax, polypropylene-strontium titanate, and strontium titanate-flax fiber interfaces. The potential use of these materials is in layered printed circuit board applications.

Application of non-woven aramid-polyimide composite materials for high reliability printed circuit boards for use in spacecraft electronics

An understanding of the impact of current trends on composites begins with the PCB material and its manufacture. Discovery, development and application of new materials are the robust power for the development of human society. With recent advances in electronics materials and designs, the electronics industry is pushing the operating temperatures to new boundaries. Electronic packaging technology is under increasing pressure to downsize devices. New dielectric composite materials have been introduced for printed circuit board applications, such as Thermount polyimide with the aim to match the requirements for high speed and high density of electronic devices that are planned for new spacecraft electronic boards. The objective of the paper is to discuss about introduction and fabrication of non-woven aramid-polyimide composite material and experiment carried out to study the effect and its application in high reliability HDI PCBs for spacecraft electronics. An experiment is made to attempt realization of PCB using “Non-woven aramid-polyimide composite substrate” as an alternative to FR4 glass reinforced substrate to achieve improved thermal characteristics and also weight reduction, which is desirable for space electronics. From the experimental results, it is evident that, introduction of thermount polyimide material has significant weight reduction and the material withstood readily six dip thermal stress tests. It is found that the usage of the above substrate has enhanced the reliability and PCBs produced have proved the ability to withstand thermal variation commonly experienced by the high-speed electronics.

A novel approach for development of printed circuit board from biofiber based composites

AbstractOver past few decades, the electronic boards density and performance are enhanced by entrenching the components in the interior surfaces of the printed circuit boards (PCBs).The worthiness of this novel innovation has to be probed to warranty the functioning of electronic boards acquiesced to callous environments. In this study, a novel advancement concentrating on the development of bio‐based materials for the PCB applications has been documented. The bio‐based composite from rice husk‐epoxy resin could impendingly substitute the conventional synthetic fiber reinforced epoxy composites in PCB applications. The essential properties of biocomposites were assessed such as tensile and bending properties, dielectric property, thermal properties, moisture absorption, microdrilling, biodegradability, and flammability. Results obtained found that, these biocomposites were promising for PCB application.

Thioetherimide-Modified Cyanate Ester Resin with Better Molding Performance for Glass Fiber Reinforced Composites.

Cyanate ester (CE) resins with higher heat resistance, lower coefficients of thermal expansion (CTEs), and lower water absorption ratios are highly desired in printed circuit boards (PCBs). In this work, a CE was modified by copolymerization with a long-chain thioether bismaleimide (SBMI) to form a thioetherimide-modified CE (SBT). The results indicated that SBT had a wider processing window and better processing properties than a common bismaleimide-modified CE resin (MBMI). After molding with a glass fiber cloth, the composites (GSBT) exhibited moisture adsorption in the range of 1.4%–2.0%, high tensile strength in the range of 311–439 MPa, good mechanical retention of 70%–85% even at 200 °C, and good dimension stability, with coefficients of thermal expansion in the range of 17.3–18.6 (×10−6 m/°C). Such GSBT composites with superior properties would be good candidates for PCB applications.

Low-Cost Wireless Temperature Measurement: Design, Manufacture, and Testing of a PCB-Based Wireless Passive Temperature Sensor.

Low-cost wireless temperature measurement has significant value in the food industry, logistics, agriculture, portable medical equipment, intelligent wireless health monitoring, and many areas in everyday life. A wireless passive temperature sensor based on PCB (Printed Circuit Board) materials is reported in this paper. The advantages of the sensor include simple mechanical structure, convenient processing, low-cost, and easiness in integration. The temperature-sensitive structure of the sensor is a dielectric-loaded resonant cavity, consisting of the PCB substrate. The sensitive structure also integrates a patch antenna for the transmission of temperature signals. The temperature sensing mechanism of the sensor is the dielectric constant of the PCB substrate changes with temperature, which causes the resonant frequency variation of the resonator. Then the temperature can be measured by detecting the changes in the sensor’s working frequency. The PCB-based wireless passive temperature sensor prototype is prepared through theoretical design, parameter analysis, software simulation, and experimental testing. The high- and low-temperature sensing performance of the sensor is tested, respectively. The resonant frequency decreases from 2.434 GHz to 2.379 GHz as the temperature increases from −40 °C to 125 °C. The fitting curve proves that the experimental data have good linearity. Three repetitive tests proved that the sensor possess well repeatability. The average sensitivity is from repetitive measurements conducted three times. This study demonstrates the feasibility of the PCB-based wireless passive sensor, which provides a low-cost temperature sensing solution for everyday life, modern agriculture, thriving intelligent health devices, and so on, and also enriches PCB product lines and applications.

Exploring Ag-doped Mullite as High Dielectric and Antimicrobial Reinforcement with Polybenzoxazine Matrix

ABSTRACTThe present work describes the development of high k dielectric aluminosilicate and its application as reinforcement with polybenzoxazine matrix to achieve high dielectric and antimicrobial nanocomposite. Initially, dielectric constant value of mullite was found to increase with respect to the percentage of Ag in mullite lattices and reached a maximum of 14.9, when doped with 5 mol%. Data from antimicrobial assay also suggest that, the zone of inhibition expands with respect to embedding silver, and thus 10 mol% of Ag-doped mullite exhibiting the highest antimicrobial property. Since, 3 mol% Ag-doped mullite hold better dielectric, various weight percentages of the same (MA3) were embedded with polybenzoxazine matrices after its surface modification. Among the resulted nanocomposite, 1.5% of glycidyl-functionalized MA3/polybenzoxazine not only showed remarkable enhancement in their thermal, dielectric, electrical conductivity but also exhibited a zone of inhibition of 11 and 12 mm against Escherichia coli and Pseudomonas aeruginosa, respectively. The enhanced thermal, dielectric, and antimicrobial properties will make this material as a suitable candidate in printed circuit board application in particularly for cold weather climatic conditions.

Crystal growth patterns in DC and pulsed plated galvanic copper films on (1 1 1), (1 0 0) and (1 1 0) copper surfaces

Copper films for printed circuit board applications have to be fine-grained to achieve even filling of vias. Electroplated Cu films on roll annealed Cu substrates may have unacceptably large epitaxial crystals. Here galvanic films were plated on oriented single-crystal Cu substrates from an additive-free electrolyte, as well as DC plating and pulse reverse (PR) plating with additives. The distribution of crystallite orientations was mapped with XRD and compared with the microstructure determined by SEM. For the additive-free bath on [111] and [100] oriented surfaces a gradual transition from epitaxial to polycrystalline is seen, while films on [110] substrates are persistently epitaxial. Without bath additives, twinning is the main mechanism for the transition to polycrystalline texture. For DC plating, additives (carriers, accelerators and levelers) promote fine-grained films with isotropic grain orientations, with films on [110] substrates being partially isotropic. Plating with carriers and accelerators (no leveler) yields films with many distinct crystallite orientations. These orientations result from up to five steps of recursive twinning. PR plating produces isotropic films with no or very few twins (〈111〉 and 〈100〉 substrates, respectively), while on 〈110〉 oriented surfaces the deposits are about 20% epitaxial.

Characterizing the conductivity of ICA joints by the mean intercept length of Ag flakes

Purpose – The purpose of this paper is to present a novel and alternative method for the characterization of isotropic conductive adhesive (ICA) joints’ conductivity by the calculation of the mean intercept length of conductive flakes in the cured joint. ICAs are widely used in the field of hybrid electronics or special printed circuit board applications, such as temperature sensitive or flexible circuits. The main quality parameters of the ICA joints are the conductivity and the mechanical strength. Design/methodology/approach – For the experiments, one-component Ag-filled thermoset ICA paste was used on FR4 printed circuit test board to join zero-ohm resistors. Six different curing temperatures were applied: 120, 150, 175, 210, 230 and 250°C. The conductivity of the joints was measured in situ during the curing process. Micrographs were taken from the cross-sectioned joints, and the mean intercept length was calculated on them after image processing steps. Findings – Results of the measured conductivity and the mean intercept length were compared, and acceptable correlation was found for what can be used for characterizing the conductibility of ICA joints. Research limitations/implications – Investigating and characterizing the conductivity of ICA joints by an image processing method. Originality/value – The main advantage of this method compared to the electrical measurements is that the conductivity characterization is possible on any kind of component. Therefore, this method can be used in any appliances not only in test circuits.

面向光印刷电路板的聚合物光波导制备及性能研究

面向光印刷电路板的聚合物光波导制备及性能研究

Fabrication and dielectric properties of BADCy/Ni0.5Ti0.5NbO4 composites for ultra-low-loss printed circuit board application

Ni0.5Ti0.5NbO4 was firstly reported as filler to adjust dielectric properties of polymer matrix composites for printed circuit board (PCB) application. In this study, the Ni0.5Ti0.5NbO4 filler was modified using γ-aminopropyl triethoxy silane (KH550). The effects of KH550 on particle lipophilicity and Bisphenol-A cyanate ester resin (BADCy) curing behavior were studied. BADCy/Ni0.5Ti0.5NbO4 composites were fabricated by the traditional casting method. The dielectric properties and moisture absorption of the composites were tested. Results show that most hydrophilic groups on the surface of Ni0.5Ti0.5NbO4 powder are replaced by lipophilic groups after modification, which results in the obvious improvement of Ni0.5Ti0.5NbO4 filler dispersion in BADCy. Beyond that, surface modification also greatly affects the curing behavior of BADCy resin. The BADCy/Ni0.5Ti0.5NbO4-KH550 composites exhibit excellent dielectric properties as well as low moisture absorption. Furthermore, the dielectric constant can be accurately predicted using Effective Medium Theory (EMT model) when the morphology factor is 0.1407.