Printed Circuit Substrate Research Articles

Phosphorus-Containing Flame-Retardant Benzocyclobutylene Composites with High Thermal Stability and Low CTE.

As a component of printed circuit substrate, copper clad laminate (CCL) needs to meet the performance requirements of heat resistance, flame retardancy, and low coefficient of thermal expansion (CTE), which, respectively, affects the stability, safety, and processability of terminal electronic products. In this paper, benzocyclobutylene (BCB)-functionalized phosphorus-oxygen flame retardant composites were prepared through introducing the BCB groups, and the performance was researched by thermogravimetric analysis, microcombustion calorimetry, and thermomechanical analysis. The research results show that these phosphorus oxide compounds containing BCB groups show good thermal stability and low total heat release (THR) after thermal curing, and the more BCB groups on the phosphorus oxide monomers, the better the thermal stability and flame retardancy of cured resins. The Td5 and THR of the composite (M3) are as high as 443 °C and 23.1 kJ/g, respectively. In addition, the CTE of M3 is as low as 16.71 ppm/°C. Introduction of BCB groups which can be crosslinked through heat to improve the thermal stability, flame retardancy, and reduced CTE of traditional organophosphorus flame retardant materials. These materials are expected to be good candidates for CCL substrates for electronic circuits.

Biodegradable and Nanocomposite Materials as Printed Circuit Substrates: A Mini-Review

Biodegradables are a promising path for the future of electronics in a greener mindset. The review study focuses on their applications and past and current research results. The paper also investigates the application of nanomaterials as fillers to control or increase the physical (electrical, mechanical, thermal) properties of biodegradable biopolymers. These biodegradables and nanocomposites are already effectively used in prototypes and advanced application areas with demanding requirements, such as flexible and wearable electronics, implantable or biomedical applications, and traditional commercial electronics. The nano-enhanced biopolymer substrates (e.g., with improved gas and water barrier functionalities) sometimes also with integrated, nano-enabled functionalities (such as electromagnetic shielding or plasmonic activity) can be beneficial in many electronics packaging and nanopackaging applications as well.

Printed Circuit Substrate Technologies for High-Frequency Communication

Printed Circuit Substrate Technologies for High-Frequency Communication

การศึกษาสภาวะที่เหมาะสมในกระบวนการทำความสะอาดพื้นผิววงจรยืดหยุ่นด้วยพลาสมา

การศึกษาสภาวะที่เหมาะสมในกระบวนการทำความสะอาดพื้นผิววงจรยืดหยุ่นด้วยพลาสมา

A Dual-Band Wireless Power Transfer and Backscatter Communication Approach for Real-Time Neural/EMG Data Acquisition

We present a dual-band approach for HF wireless power delivery and UHF backscatter communication in implanted biomedical devices. A testbed is described including a custom implant device as well as an external system based around the USRP B210 software defined radio platform. The implant integrates a binary phase shift keying backscatter uplink rate of 5 Mb/s, with an HF wireless power transfer link delivering 1.33 mW at an efficiency of 17%. The implant is 25 mm in diameter and 2.8 mm thick, including the printed circuit substrate, dual-band antenna, all circuitry, and biocompatible silicone encapsulation. It supports up to ten neural and four electromyogram (EMG) channels with a sampling rate of 26.10 kHz for the neural channels and 1.628 kHz for the EMG channels. The communication link is shown to have 0% packet error rate at an implant depth of up to 2.5 cm.

Highly mechanical strength and thermally conductive bismaleimide–triazine composites reinforced by Al2O3@polyimide hybrid fiber

Bismaleimide–triazine (BT) resins have received a great deal of attention in microelectronics due to its excellent thermal stability and good retention of mechanical properties. Thereafter, developing BT based composites with high mechanical strength, thermal conductivity and dielectric property simultaneously are highly desirable. In this study, one hybrid fiber of Al2O3 nanoparticle (200nm) supported on polyimide fiber (Al2O3@PI) with core–shell structure was introduced into BT resin to prepare promising Al2O3@PI–BT composite. The results indicated that the resultant composites possessed high Young’s modulus of 4.06GPa, low dielectric constant (3.38–3.50, 100kHz) and dielectric loss (0.0102–0.0107, 100kHz). The Al2O3@PI hybrid film was also conductive to improve thermal stability (Td5% up to 371°C), in-plane thermal conductivity (increased by 295% compared to that of the pure BT resin). Furthermore, the Al2O3@PI–BT composite were employed to fabricate a printed circuit substrate, on which a frequency “flasher” circuit and electrical components worked well.

Manufacturing process for piezoelectric strain sensor sheet involving transfer printing methods

In this paper, we present a novel sensor sheet manufacturing process that involves transfer printing methods using adhesive rubber stamps. By using these methods, not only ultrathin microsensors but also microcontroller and amplifier chips required for the fabrication of sensor devices can be mounted. We successfully transfer-printed a very fragile 5-mm-long, 1-mm-wide, 5-µm-thick high-aspect-ratio ultrathin strain sensor onto a flexible printed-circuit substrate. Then, we connected the sensor to the wiring by printing a conductive paste using a screen printer. A large ferroelectric polarization-voltage hysteresis curve was obtained even after the transfer printing process. Since an output voltage corresponding to the magnitude of the strain from the developed sensor was generated, it was confirmed that ultrathin sensors could be transfer-printed to the flexible substrate by this transfer technique without damage.

Encapsulating carbon nanotubes with SiO2: a strategy for applying them in polymer nanocomposites with high mechanical strength and electrical insulation

SiO2coated multiwalled carbon nanotubes filled polymer nanocomposites with high mechanical strength and electrical insulation were developed and employed to fabricate a printed circuit substrate.

Implantable probe with split anchors via residual stress and induced cell growth with gelatin nanofibres

A bipolar electrode probe used for implantable nerve stimulation treatments in minimally invasive surgeries is presented. The probe is composed of a flexible printed circuit substrate and a patterned SU-8 film. This probe features a three-dimensional (3D) tweezer-like mechanism opened by residual stress from the SU-8 film, designed to fix the probe in the tissue surrounding a target nerve. Stripes on the SU-8 film direct the net residual stress in a single direction to form a curve. The holding strengths of the probes with different deformations are defined and measured by a tensile test. Results show that the fixing ability of a 3D probe is better than a plane probe. The probes with curvature heights between 13 and 14 mm have a maximum average breaking force of 0.258 N, which is 16.3 and 13.1% higher than the probes with curvature heights between 9 and 10 mm and between 10 and 11 mm, respectively. In addition, a film of gelatin fibrous membrane, produced by electrospinning, covers the fixed ends of the probe's anchors and acts as cell scaffolds to induce cell growth, which help to ensure long-term fixation in the body. 3T3 fibroblast cells are grown to verify the scaffold effect of the fibrous membrane.

Synthesis, property and application of PZT/P(VDF-TrFE) composite film fabricated on polyimide substrate

In this paper, a flexible pyroelectric sensor using PbZr0·3Ti0·7O3 PZT/P(VDF-TrFE) materials on the polyimide (PI) flexible printed circuit substrate was reported. The fabrication processes, material electric properties and infrared photoelectric response property of the designed sensor were studied. First, the PZT ceramic powder was annealed at temperatures ranging from 300 to 900°C, and then 0–3 PZT/PVDF-TrFE composites films were produced by casting PZT/PVDF-TrFE suspension onto the flexible PI substrates. The highest pyroelectric coefficient obtained using 700°C annealed PZT particulates was 96 µC m−2 K−1, which was 20% higher than that of unannealed powders. The PI thermal insulation layer and thermal insulation tanks fabricated by laser microetching have been used to improve the photoelectric response ability of the infrared sensor. The specific detectivity of the sensors was calculated from the voltage responsivity and noise. Detectivity D* of the PZT/P(VDF-TrFE) infrared sensor was 1·17×108 cm Hz1/2 W−1 at 138·3 Hz modulation frequency. These results demonstrate that the pyroelectric infrared sensor possesses potential applications in flexible electronics.

Mechatronics Education in School of Design – Development of Educational Tool to Study Design Expression Using Mechatronics

We developed a printed circuit substrate for studying electronic devices and a PIC processor for design expressions in the mechatronics class of Sapporo City University, School of Design, Product Design Course. We then taught PIC assembler programming for LED blinking control, feedback from sensors and switches, the servomotor driving, and sequential feedback. Students in this class was given a subject to realize an actual model for the design expression of something that moves in reaction to human actions using these skills.

A Concise Periodic Undulate Sine Rectangular Waveguide Bandpass Filter for Millimeter Wave Region

A novel sine rectangular waveguide (SRW) structure with either broad or narrow side periodic undulation is firstly proposed for designing bandpass filter (BPF) at millimeter wave frequency range. The bandpass characteristics of the SRW and two BPFs with a concise transition operated at millimeter wave atmospheric window frequency are studied. The SRW has the advantages of remarkable simplicity and completely closed environment without energy leaking. Besides, energy transmission mode in SRW is a quasi TE10 mode which is similar to that in rectangular waveguide, which means that a SRW can easily get transition to a rectangular waveguide. So, compared to the traditional waveguide cavity BPF using metal diaphragm, printed circuit substrate or complex cross section, the SRW can be directly connected to a standard waveguide without additional metal diaphragm or substrate. To verify the bandpass characteristics of SRW, Ka band SRW BPF was designed and fabricated. Experimental results show low insertion loss (< 0.2 dB) in the whole Ka passband and sharp, wide rejection in the stopband (below-20 dB), with good agreement with simulated results. Therefore, the SRW will have wide potential applications in millimeter wave frequency range.

Design and Characterization of the EBG Waveguide-Based Interconnects

An alternative signal guiding structure, which can be integrated within the printed circuit substrates, is investigated in this paper. The structure is realized by forming a rectangular waveguide in a 2-D electromagnetic bandgap (EBG) substrate. In this manner, a bandpass interconnect is provided that proves to be a promising technology for the high-speed/high-frequency system design. A systematic approach to the design and optimization of this interconnect is presented here followed by investigation of various bend geometries. The studied structures exhibit very low levels of loss and leakage when inspected at tens of gigahertz frequency range. Moreover, the near-end and the far-end crosstalks are monitored in multiple interconnects proving the high efficiency of this alternative routing structure in dense layouts. Nonetheless, the crosstalk performance is degraded as the coplanar microstrip-to-waveguide transitions are added. These transitions are essentially tapered microstrip lines that are connected to other circuitries. Continuous via fences are inserted in the transition sections of multiple structures demonstrating significant improvement in the crosstalk performance.

Large‐tolerant “OptoBump” interface for interchip optical interconnections

AbstractOptical interconnection technology for optical interboard and interchip connections will be an important technology in the next‐generation communication equipment seeking a high‐capacity throughput at the terabit per second level. With the objective of establishing an economical optical packaging technology, we propose an “optical I/O chip package,” which is an optical package for the hybrid integration of optoelectric (O/E) devices and LSI chips that can be mounted on a printed‐circuit board by standard surface mount technology (SMT). In this paper, we propose the OptoBump interface as the optical interconnection between the optical package and the board that connects these two elements by forming the microlens on both and using collimated light. Accommodating the fibers on the board and connecting the connectors become unnecessary because the connections having large beam diameters are able to tolerate offsets in the SMT mounting position. First, we calculated the required collimated beam diameter of 104 µm under the assumption of an SMT accuracy of ±50 µm. Next, we applied ray tracing to estimate the optical losses of the 45° mirror at the polymer optical waveguide facet integrated into the printed‐circuit substrate and clearly exhibited the incident beam conditions with both improved losses and tolerances. And we integrated the polymer microlens into the polymer optical waveguide and the surface‐emitting laser (VCSEL) and experimentally evaluated the optical coupling performance between them. The results verified a 1‐dB tolerance at ±50 µm and demonstrated the effectiveness of this proposal. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 86(1): 1–8, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10025

Electrostatic Printing of Parmod&amp;#x2122; Electrical Conductors

A new family of liquid toners has been developed to print conductive traces on printed circuit boards by a digital printing technology. The new toners are based on Parmod&#x2122; technology which has been developed to enable low cost production of printed circuits by a simple print-and-heat process. The novel feature of these printable materials is that they cure to pure metallic conductors in seconds at a temperature low enough to be compatible with polymer-based printed circuit substrates. The resulting circuit traces have high electrical conductivity and are solderable. The use of conventional printed circuit substrates and the speed of the process permit high-production, low-cost roll to roll processing.The extension of Parmod&#x2122; technology to liquid toners provides two major additional benefits: 1) It provides a major increase in resolution for production of advanced technology high density interconnect structures, and 2) It permits direct digital printing of circuits from CAD files with no intermediate tooling requirements. The latter capability realizes the goal of total CAD/CAM integration and the ultimate in manufacturing flexibility. This paper discusses the characteristics of Parmod&#x2122; technology, the performance of the liquid toners based on it and some applications of the technology which can be foreseen.

The orientation of mesophase pitch during fully developed channel flow

Mesophase pitch-based carbon fibers are ideally suited for applications where the rapid dissipation of heat is important (structural composites, printed circuit substrates, etc.). However, control of texture is essential in order to optimize fiber properties, especially thermal conductivity. Because ribbon-shaped mesophase pitch-based carbon fibers possess a highly linear texture, these fibers are very promising for high thermal conductivity applications. The observed texture of these ribbon-shaped fibers and the radial texture commonly observed in circular fibers can be predicted from liquid-crystal flow theory, where the precursor molecules are modeled as rigid disks.In order to determine the orientation of flowing mesophase pitch, a capillary rheometer was modified to quench capillaries during extrusion. Aluminum capillaries were constructed with rectangular channels down the center (with a 9:1 aspect ratio). The capillaries containing the mesophase samples were mounted in low-viscosity epoxy resin and cured. The desired mesophase surface (transverse or longitudinal) was isolated by grinding and polishing the samples to 3 gmm. Then the pitch surface was observed optically under cross-polarized light. The transverse surfaces of mesophase pitch indicated an orientation pattern where the aromatic rings lie perpendicular to the channel walls. This result is consistent with that predicted by the liquid-crystal flow theory, as well as with the textures of carbonized fibers.

Anisotropically conductive adhesive flip-chip bonding on rigid and flexible printed circuit substrates

A systematic experiment on flip-chip bonding assembly using an anisotropically conductive adhesive (ACA) has been carried out. The assembled modules have been characterized by a number of environmental tests, including aging, constant humidity, temperature cycling, humidity cycling, shear, vibration, and shock testing. The results indicate that under optimum process conditions, high quality and high reliability joints can be achieved. Conduction failure mechanisms have been investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The analysis shows that failure is dependent on competition between driving factors; thermal stress, elastic stress, expansion due to moisture absorption on one side, and the resistant factor, i.e., interatomic force. Variation of the filler size in the ACA, configurations of chips and boards, as well as bonding pressure and its distribution are among the most important factors that control the bonding quality and reliability.

Equipment Selection for Tape Automated Bonding (TAB)

The manufacturing process involving the bonding of ultra‐fine pitch TAB solder joints into printed circuit substrates requires precision equipment. This paper describes the basic components of any type of outer lead bonding (OLB) TAB equipment. It goes on to explain a selection methodology to be used when selecting equipment for customer applications. Specific examples are used to aid the equipment consumer in selecting the optimum equipment set and verifying the machine's accuracy and reliability.

An SEM analysis of the voltage induced upon a printed strip antenna by a transient plane wave

The singularity expansion method (SEM) is applied to study the interaction of a transient electromagnetic plane wave with a printed strip antenna. In SEM, the time-domain response of the element is separated into excitation-independent natural resonances and modes, which have considerable physical significance, and closed-form coupling terms which can be rapidly evaluated as the geometric or temporal properties of the source change. The SEM is demonstrated as applied to the transient microstrip problem, and the effect of varying the properties of the printed circuit substrate over a range of values typically found in microstrip antenna applications is studied. The transient response due to a step and Gaussian excitation is studied. It is found that the level of transient signal induced on a printed element increases with increasing substrate permittivity. The shape of the induced voltage or current waveform is highly dependent on the geometric and temporal properties of the source for elements printed on relatively thin substrates, while, for elements printed on thicker substrates, the shape of the induced waveform is much less sensitive to the form of the excitation, and resembles the oscillation of the fundamental resonance of the antenna. >

A volume and surface source integral formulation for electromagnetic scattering from printed circuit antennas

The authors present a volume integral formulation in conjunction with a method of moments solution for electromagnetic scattering from two- and three-dimensional homogeneous dielectric printed circuit substrates. The theory for printed circuits consisting of dielectric substrates and conducting surfaces is presented. The TE scattering from a dielectric cylinder and a dielectric sheet are computed and compared to other numerical results. The results for electromagnetic scattering from a three-dimensional dielectric cube are compared to other results. >