Search results

1 – 9 of 9
Article
Publication date: 2 February 2018

Wojciech Stęplewski, Andrzej Dziedzic, Kamil Janeczek, Aneta Araźna, Krzysztof Lipiec, Janusz Borecki and Tomasz Serzysko

The purpose of this paper is to investigate the behavior of embedded passives under changing temperature conditions. Influence of different temperature changes on the basic…

133

Abstract

Purpose

The purpose of this paper is to investigate the behavior of embedded passives under changing temperature conditions. Influence of different temperature changes on the basic properties of embedded passives was analyzed. The main reason for these investigations was to determine functionality of passives for space application.

Design/methodology/approach

The investigations were based on the thin-film resistors made of Ni-P alloy, thick-film resistors made of carbon or carbon-silver inks, embedded capacitors made of FaradFlex materials and embedded inductor made in various configurations. Prepared samples were examined under the influence of a constant elevated temperature (100, 130 or 160°C) in a long period of time (minimum of 30 h), thermal cycles (from −40 to +85°C) or thermal shocks (from −40 to +105°C or from −40 to +125°C).

Findings

The achieved results revealed that resistance drift became bigger when the samples were treated at a higher constant temperature. At the same time, no significant difference in change in electrical properties for 50 and 100 Ω resistors was noticed. For all the tests, resistance change was below 2 per cent regardless of a value of the tested resistors. Conducted thermal shock studies indicate that thin-film resistors, coils and some thick-film resistors are characterized by minor variations in basic parameters. Some of the inks may show considerable resistance variations with temperature changes. Significant changes were also exhibited by embedded capacitors.

Originality/value

The knowledge about the behavior of the operating parameters of embedded components considering environmental conditions allow for development of more complex systems with integrated printed circuit boards.

Article
Publication date: 6 February 2017

Wojciech Steplewski, Andrzej Dziedzic, Janusz Borecki and Tomasz Serzysko

The purpose of this paper is to investigate the basic functional parameters of passive embedded components in printed circuit boards (PCBs) under environmental exposures such as…

224

Abstract

Purpose

The purpose of this paper is to investigate the basic functional parameters of passive embedded components in printed circuit boards (PCBs) under environmental exposures such as thermal-humidity and thermal exposure.

Design/methodology/approach

The investigations were based on the thin-film resistors made of NiP alloy, thick-film resistors made of carbon or carbon–silver inks, embedded capacitors made of FaradFlex materials and embedded inductor made in various configurations. The capacitors and thin- and thick-film resistors were tested in the climatic chamber in conditions of thermal-humidity exposure at 85°C and 85 per cent RH for 500 h. The embedded inductors were tested in two different environmental conditions: thermal-humidity exposure at 60°C and 95 per cent RH, and thermal exposure at 150°C and additionally at the temperature in the range of +25°C to +150°C.

Findings

Studies show that in the case of embedded capacitors, the changes caused by exposure to thermal-humidity are durable and lead to the capacity increase. The embedded thin-film resistors behave in the same manner, whereas the thick-film resistors were the least resistant to the conditions of exposure. Most of the polymer thick-film resistors have been damaged. The changes of coils' properties during aging are small, and what is most important is that, after some time of exposure, their parameters stabilize at a particular level. The changes resulting from the increase in temperature are typically related to the change of material resistance (Cu) of which coils are made, and as such, they cannot be avoided but they can be predicted.

Research limitations/implications

The realized studies allowed determination of the properties of the embedded passive elements with respect to specific environmental exposures. The studies show that embedded resistors can be used interchangeably with chip passive elements. It allows saving the area on the surface of PCB, occupied by these passive elements, for assembly of active elements integrated circuits (ICs) and thus enabling the miniaturization of electronic devices.

Originality/value

The knowledge about the behavior of the operating parameters of embedded components, considering the environmental conditions, allows for development of more complex systems with integrated PCBs.

Article
Publication date: 6 February 2017

Janusz Sitek, Marek Koscielski, Janusz Borecki and Tomasz Serzysko

The purpose of this paper is to evaluate the influence of solder powders sizes applied in soldering materials used for Package-on-Package (PoP) system manufacture as well as other…

Abstract

Purpose

The purpose of this paper is to evaluate the influence of solder powders sizes applied in soldering materials used for Package-on-Package (PoP) system manufacture as well as other factors on reliability and mechanical strength of created solder joints in three-dimensional (3D) PoP structures.

Design/methodology/approach

The design of experiments based on the Genichi Taguchi method were used in the investigation. The main factors covered different printed circuit board (PCB) coatings, soldering materials with solder powders sizes from Types 3 to 7 and soldering profiles. The reliability of 3D PoP structures was determined by measurements of resistance of daisy-chain solder joints systems during thermal shocks (TS) cycles. The mechanical strength of solder joints in 3D PoP structures was determined by measurements of a shear force of “Top” layer of 3D structures at T0 and after 1,500 TS. The ANOVA was used for results assessment.

Findings

The size of solder powders applied in soldering materials had small (10 per cent) influence on mechanical strength of solder joints in 3D PoP structures. Small size of solder powder had positive effect on solder joints reliability in 3D PoP structures. Especially important was the selection of solder paste for “Bottom” layer of 3D PoP system (influence 17 per cent). Incorrect soldering profile (influence 46 per cent) or wrong selected PCB coating (influence 35 per cent) can very easily reduce the positive impact of soldering materials on solder joints reliability. It was stated that as low as possible soldering profile and organic solderability preservative (OSP) coating in the case of single-sided PCB are the best for 3D PoP structures due to their reliability.

Originality/value

This paper explains how different sizes of solder powders used nowadays in solder pastes influence on reliability and mechanical strength of the solder joints in 3D PoP structures. The contribution, in numerical values, of soldering materials, soldering profile and PCB coating on 3D PoP structures solder joints reliability as well as recommendations improving reliability of 3D PoP structures solder joints were presented.

Details

Soldering & Surface Mount Technology, vol. 29 no. 1
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 1 February 2016

Wojciech Grzesiak, Piotr Maćków, Tomasz Maj, Beata Synkiewicz, Krzysztof Witek, Ryszard Kisiel, Marcin Myśliwiec, Janusz Borecki, Tomasz Serzysko and Marek Żupnik

This paper aims to present certain issues in direct bonded copper (DBC) technology towards the manufacture of Al2O3 or AlN ceramic substrates with one or both sides clad with a…

Abstract

Purpose

This paper aims to present certain issues in direct bonded copper (DBC) technology towards the manufacture of Al2O3 or AlN ceramic substrates with one or both sides clad with a copper (Cu) layer.

Design/methodology/approach

As part of the experimental work, attempts were made to produce patterns printed onto DBC substrates based on four substantially different technologies: precise cutting with a diamond saw, photolithography, the use of a milling cutter (LPKF ProtoMat 93s) and laser ablation with differential chemical etching of the Cu layer.

Findings

The use of photolithography and etching technology in the case of boards clad with a 0.2-mm-thick Cu layer, can produce conductive paths with a width of 0.4 mm while maintaining a distance of 0.4 mm between the paths, and in the case of boards clad with a 0.3-mm-thick copper layer, conductive paths with a width of 0.5 mm while maintaining a distance of 0.5 mm between paths. The application of laser ablation at the final step of removing the unnecessary copper layer, can radically increase the resolution of printed pattern even to 0.1/0.1 mm. The quality of the printed pattern is also much better.

Research limitations/implications

Etching process optimization and the development of the fundamentals of technology and design of power electronic systems based on DBC substrates should be done in the future. A limiting factor for further research and its implementation may be the relatively high price of DBC substrates in comparison with typical PCB printed circuits.

Practical implications

Several examples of practical implementations using DBC technology are presented, such as full- and half-bridge connections, full-wave rectifier with an output voltage of 48 V and an output current of 50 A, and part of a battery discharger controller and light-emitting diode illuminator soldered to a copper heat sink.

Originality/value

The paper presents a comparison of different technologies used for the realization of precise patterns on DBC substrates. The combination of etching and laser ablation technologies radically improves the quality of DBC-printed patterns.

Details

Circuit World, vol. 42 no. 1
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 28 January 2014

Wojciech Steplewski, Andrzej Dziedzic, Janusz Borecki, Grazyna Koziol and Tomasz Serzysko

The purpose of this paper is to investigate the influence of parameters of embedded resistive elements manufacturing process as well as the influence of environmental factors on…

Abstract

Purpose

The purpose of this paper is to investigate the influence of parameters of embedded resistive elements manufacturing process as well as the influence of environmental factors on their electrical resistance. The investigations were made in comparison to the similar constructions of discrete chip resistors assembled to standard printed circuit boards (PCBs).

Design/methodology/approach

The investigations were based on the thin-film resistors made of NiP alloy, thick-film resistors made of carbon or carbon-silver inks as well as chip resistors in 0402 and 0603 packages. The polymer thick-film resistive films were screen-printed on the several types finishing materials of contact terminations such as copper, silver, and gold. To determine the sensitivity of embedded resistors versus standard assembled chip resistors on environmental exposure, the climatic chamber was used. The measurements of resistance were carried out periodically during the tests, and after the exposure cycles.

Findings

The results show that the change of electrical resistance of embedded resistors, in dependence of construction and base material, is different and mainly not exceed the range of 3 per cent. The achieved results in reference to thin-film resistors are comparable with results for standard chip resistors. However, the results that were obtained for thick-film resistors with Ag and Ni/Au contacts are similar. It was not found the big differences between resistors with and without conformal coating.

Research limitations/implications

The studies show that embedded resistors can be used interchangeably with chip resistors. It allows to save the area on the surface of PCB, occupied by these passive elements, for assembly of active elements (ICs) and thus enable to miniaturization of electronic devices. But embedding of passive elements into PCB requires to tackle the effect of each forming process steps on the operational properties.

Originality/value

The technique of passive elements embedding into PCB is generally known; however, there are no detailed reports on the impact of individual process steps and environmental conditions on the stability of their electrical resistance. The studies allow to understand the importance of each factor process and the mechanisms of operational properties changes depending on the used materials.

Details

Circuit World, vol. 40 no. 1
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 3 August 2015

Wojciech Stęplewski, Andrzej Dziedzic, Adam Kłossowicz, Paweł Winiarski, Janusz Borecki, Grażyna Kozioł and Tomasz Serzysko

– This paper aims to report the investigations of capacitors and inductors embedded into printed circuit boards (PCBs) designed in various layouts.

Abstract

Purpose

This paper aims to report the investigations of capacitors and inductors embedded into printed circuit boards (PCBs) designed in various layouts.

Design/methodology/approach

The research were focused on the components embedded into four-layer PCBs with different structures of the inner layers. Three special capacitive laminates for manufacturing of thin-film embedded capacitors and several types of coils in the form of a spiral, meander and solenoid are described. In addition, a part of the spiral-type coils was formed with an aperture in the center in which the magnetic core, made of soft magnetic composites’ material was placed to increase the coil inductance.

Findings

Various constructions of embedded capacitors and coils were designed and manufactured. Capacitance and loss tangent of capacitors to determine the repeatability of the production process were determined. Capacitor’s long-term stability analysis was performed by exposing test samples to elevated temperatures (70, 100 or 130°C), realized with the aid of heating plate, for at least 160 h. The temperature characteristics for the capacitance and loss tangent from 15 to 100°C were determined. Also the induction of different designs and layouts coils was determined.

Originality/value

The wide parameters’ characterization of capacitors and coils embedded into PCBs allow the analysis of their properties with regard to their practical application. The promising results of the realized measurements show that the capacitors and induction coils with studied structures can be widely used in the construction of embedded circuits into PCBs (e.g. filters, radio frequency identification systems and generators).

Article
Publication date: 28 January 2014

Wojciech Steplewski, Andrzej Dziedzic, Janusz Borecki, Grazyna Koziol and Tomasz Serzysko

The purpose of this paper is to investigate the thermal behaviour of thin- and thick-film resistor with different dimensions and contacts embedded into printed circuit board (PCB…

Abstract

Purpose

The purpose of this paper is to investigate the thermal behaviour of thin- and thick-film resistor with different dimensions and contacts embedded into printed circuit board (PCB) and compare them to the similar constructions of discrete chip resistors assembled to standard PCBs.

Design/methodology/approach

In investigations the thin- and thick-film embedded resistors with the bar form in different dimensions and configurations of contacts as well as rectangular chip resistors in package 0603 and 0402 were used. In tests were carried out the measurements of dissipated power in temperature of resistor about 40°C, 70°C and 155°C. The power dissipation was calculated as a multiplying of electrical current flowing through the resistor with voltage across the resistor. The dissipation of heat generated by electrical current flowing through resistors was examined by means of the FLIR A320 thermographic camera with lens Closeup×2 and the power source.

Findings

The results show that, in case of chip resistors, the intensity of heat radiation strongly depends on dimensions of copper contact lands and also depends on the dimensions of the resistor. In case of embedded resistors, with comparable dimensions to chip resistors, they have lower ability to power dissipation, as well as the copper contact lands dimensions have lower influence. The thermal radiation through resin material is not as effective as it is in case of resistors assembled on PCB. However, the embedded thick-film resistors, especially made of paste Minico M2010, have already the similar parameters to 0402 chip resistors.

Research limitations/implications

Research shows that embedded resistors can be used interchangeably with SMD resistors it allows to open up space on the surface of PCB, but it should be taken into account the lower energy dissipation capabilities. It is suggested that further studies are necessary for accurately determining the thermal effects and investigate the structures of embedded passive components that allow for better heat management.

Originality/value

Thermal stability of embedded resistors during operation is a critical factor of success of embedded resistor technology. The way of power dissipation and heat resistance are one of the important operating parameters of these components. The results provide information about the power and the energy dissipation of embedded thin- and thick-film resistors compared to the standard surface mount technology.

Details

Circuit World, vol. 40 no. 1
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 1 February 2016

Janusz Borecki and Tomasz Serzysko

The purpose of this paper is to determine the dependence of mechanical strength of solder joints on printed circuit boards from the soldering process parameters and operating…

Abstract

Purpose

The purpose of this paper is to determine the dependence of mechanical strength of solder joints on printed circuit boards from the soldering process parameters and operating conditions of the electronic device.

Design/methodology/approach

The research was performed using the Taguchi method of planning of experiments. Evaluation of the quality of solder joints was made on the basis of microscopic observations, X-ray analysis and measurements of shear force of solder joints.

Findings

The carried out research has shown the influence of the individual parameters of the soldering process on the mechanical strength of solder joints and the mechanism of damage of solder joints under the influence of shear force.

Originality/value

The authors present results of their research using advanced techniques of experimental design and analysis of results. In this study, original approach was used to simulate the operational conditions of electronic devices including thermal imaging technology.

Details

Soldering & Surface Mount Technology, vol. 28 no. 1
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 22 June 2012

Kamil Janeczek, Tomasz Serzysko, Małgorzata Jakubowska, Grażyna Kozioł and Anna Młożniak

The purpose of this paper is to investigate the durability of radio‐frequency identification (RFID) chips assembled on flexible substrates (paper and foil), with materials…

Abstract

Purpose

The purpose of this paper is to investigate the durability of radio‐frequency identification (RFID) chips assembled on flexible substrates (paper and foil), with materials evaluated with regard to mechanical stresses and dependence on the applied substrate, antenna materials, chip pad printing and chip encapsulation.

Design/methodology/approach

RFID chips were assembled to antennas screen printed on flexible substrates. Shear and bending tests were conducted in order to evaluate the mechanical durability of the chip joints depending on the materials used for mounting the RFID chip structures. X‐ray inspection and cross sectioning were performed to verify the quality of the assembly process. The microstructure and the resistance of the materials used for chip pads were investigated with the aim of determining the conductivity mechanism in the printed layers.

Findings

Addition of carbon nanotubes to the conductive adhesive (CA) provided a higher shear force for the assembled RFID chips, compared to the unmodified conductive adhesive or a polymer paste with silver flakes. However, this additive resulted in an increase in the material's resistance. It was found that the RFID substrate material had a significant influence on the shear force of mounted chips, contrary to the materials used for printing antennas. The lower shear force for chips assembled on antennas printed on paper rather than on foil was probably connected with its higher absorption of solvent from the pastes. Increasing the curing temperature and time resulted in an additional increase in the shear force for chips assembled to antennas printed on foil. A reverse dependence was observed for chips mounted on the antennas made on paper. An improvement in the durability of the RFID chip structures was achieved by chip encapsulation. Bending tests showed that a low‐melting adhesive was the best candidate for encapsulation, as it provided flexibility of the assembled structure.

Research limitations/implications

Further studies are necessary to investigate the mechanical durability of RFID chips assembled with a conductive adhesive, with different addition levels and types of carbon nanotubes.

Practical implications

The results revealed that the best candidate for providing the highest RFID chip durability related to mechanical stresses was the low‐melting adhesive. It can be recommended for practical use, as it simplified the assembly process and reduced the curing step in the encapsulation of the RFID devices. From the results of shear testing, conductive adhesives with carbon nanotubes can be used in RFID chip assembly because of their ability to increase the shear force of joints created between the antenna and the chip.

Originality/value

In this paper, the influence of the materials used for antenna, chip pads, encapsulation and the curing conditions on the mechanical durability (shear and bending) of RFID chips was analyzed. Commercial and elaborated materials were compared. Some new materials containing a conductive adhesive and carbon nanotubes were proposed and tested in RFID chip assembly to antennas printed on flexible substrates (paper and foil).

1 – 9 of 9