Frederick Bossuyt

imec · Centre for Microsystems Technology (CMST)

The integration of structural electronics in injection-molded parts is a challenging step. The films—comprising of laminated stacks with electronics—are exposed to shear stresses and elevated temperatures by the molten thermoplastic. Hence, molding settings have a significant impact on the successful, damage-free manufacturing of such parts. In thi...

Over-molding has been proposed in recent years as an integrated functional flexible circuit board in a plastic part. This method uses the conventional process for film insert technology. Over-molding has attracted significant attention across many industries due to its potential to deliver different electrical functions in a variety of different pa...

This research presents an innovative method to accurately and repeatedly position electronic components in thermoformed electronics. The paper focuses on 3D shaped electronics, which are made up of stretchable metal structures integrated into thermoformable material. We used the degree of freedom theory to develop a design method that allows us to...

Curve-shaped electronics have been on the rise in recent years. One crucial challenge in this area is reproducibility, which means in the different fabricated samples, the position of the electronic components should be the same. This paper aims to present a reliable approach for accurate component positioning in thermoformed electronics. We have p...

This paper aims to present a reliable approach for accurate component positioning in thermoformed electronics. We have proposed a non-stretchable conductive structure for accurate positioning of the electronic components, which can assure the conductive traces' mechanical stability during lamination and thermoforming of the substrate. We have verif...

Advancements in wearable technology and smart textiles have also opened new possibilities in the sports and medical fields. One of the examples of a relevant application case can be found in cycling. This paper expands on previous research on stretchable electronics on knit fabrics. It describes the development of stretchable circuits for the lower...

A great deal of attention has been paid in recent years to the integration of two and three-dimensional integrated electronic parts into plastics, both for their potential applications in modern human lives and for their outstanding properties, which include the ability to reduce product weight and space while increasing product reliability. The de...

This paper presents a novel approach for removing out-of-plane deformation in stretched metal interconnects by adding a fractal structure to the original meander shape and using an optimized fabrication stack. In thermoformed electronics, in cases where copper is used as conductor, the twisting of meander-shaped structures caused by excessive mecha...

Electronic textiles (e-textiles) and wearable computing have been emerging increasingly during the last decade. Since the market interest and predictions have grown, the research into increasing reliability and durability of wearables and e-textiles is developing rapidly. The washability of different integration methods and resistance to mechanical...

With the increasingly high demand for flexible microsystems, their embedding technologies have become more and more important. In this paper, we present the developments of over-molding technology to realize polyimide–copper (PI/Cu) electronic circuits embedded in plastics. The circuit consists of Cu interconnections on a PI substrate with assemble...

The smart textiles and wearable technology markets are expanding tirelessly, looking for efficient solutions to create long-lasting products. The research towards novel integration methods and increasing reliability of wearables and electronic textiles (e-textiles) is expanding. One obstacle to be tackled is the washability and the endurance to mec...

Today’s world is full of intelligent electronics and with the development of flexible printed electronics technologies, different integration approaches are of high demand. The combination of electronics with polymer is a new technology platform as it integrates multiple functionalities into plastic products. This work shows preliminary results in...

The primary bottleneck of the stretchable mold interconnect (SMI) technology is its reliance on carrier boards. These are necessary to handle the meandered circuit during production and to ensure dimensional stability of the flexible circuit board before encapsulation. However, for all the problems it solves, it also introduces a new major problem...

Stretchable circuit technology, as the name implies, allows an electronic circuit to adapt to its surroundings by elongating when an external force is applied. Based on this, early authors proposed a straightforward metric: stretchability—the percentage length increase the circuit can survive while remaining functional. However, when comparing tech...

Conventional electronic circuits are made up of electronic components assembled on either rigid substrates like FR4 and ceramic or on flexible substrates based on polymers such as polyimide, PET and PEN foils. The latter type of substrates offers considerable improvements in freedom of motion over its rigid complement although the deformations are...

A method to fabricate thermoplastically deformable electronic circuits is presented, with the intent of achieving low-cost 2.5D free-form rigid smart objects. This by utilizing existing flexible circuit technology based stretchable circuits, in combination with thermoplastic materials. After fabricating the circuit in a flat state, a thermoforming...

This contribution describes an efficient process flow for production of one-time deformable electronic devices based on standard circuit board technology and demonstrates multiple devices fabricated using this technique. The described technology has the potential to streamline and simplify the production of complex user interfaces which typically r...

In this paper we present a technology for the production of randomly shaped 3D electronic circuits, which is complementary to the 3D-MID technology. The technology is based on conventional printed circuit board (PCB) technology, thermoplastic polymer encapsulation and thermoforming of the flat polymer carrier with the embedded circuit. Meander shap...

Conformable electronics, electronics that can be integrated into ergonomically or aesthetically 2.5/3D shape surfaces, have received a tremendous attention during recent years. So far, various materials, designs and fabrication methods were developed for the realization of dynamically-stretchable (elastic) circuits.

In this paper, we present the developments of a new technology to realize 2.5-/3-D electronic circuits. The starting point is an electronic circuit embedded in a hard thermoplastic material, which is transformed into a 2.5-/3-D shape using a thermoforming process. The electronic circuit consists of stretchable copper interconnections in combination...

Dielectric analysis has attracted great attention in recent years for the monitoring of composite production processes because of its capability to be applied in situ and in real-time. However, to progress from lab to industry level, the sensor system should be as sensitive and reliable as possible, whereas its fabrication should be simple and cost...

Today a need is emerging for embedding electronic and sensor functions in the products which needs these functions, and, importantly, to do this without noticeably influencing the mechanical design of the product. This contribution describes an approach used to produce a 2.5/3D free-form rigid and smart objects or randomly shaped circuit. The propo...

This contribution describes the technology used to produce thermoplastically deformable electronics, based on flexible circuit board technology, to achieve low-cost 2.5D free-form rigid smart objects. These one-time deformable circuits employ a modified version of the previously developed meander-based “polymer-last” technology for dynamically stre...

We present a str etchable and foldable passive matrix driven display using 45 by 80 RGB LED's mounted on a meandering printed circuitry embedded in a polyurethane film. The meander interconnections have been optimized with respect to their electrical and mechanical properties to provide a display with a 3 mm pitch between the pixels and a stretchab...

A technology is presented for the production of soft and rigid circuits with an arbitrary 2.5D fixed shape. The base of this technology is our proprietary technology for elastic circuits with a random shape, in which the elastic thermoset (mostly PDMS) polymer is now replaced by soft or rigid thermoplastic variants. An additional thermoforming step...

Fibre Reinforced Polymer (FRP) is becoming a valid alternative to many traditional heavy metal industries because of its high specific stiffness over the more classical construction metals. Recent trend of more complex geometry of composites is causing increasing difficulty in composite manufacturing. A method to optimize the manufacturing process...

This contribution describes considerations and very preliminary results in the technology development of thermoplastically deformable electronics and sensor circuits, with the intention to eventually achieve the low-cost fabrication of 2.5D free-form rigid smart objects. The technology is based on the one for elastic circuits, developed and charact...

The continuous growth of the composites industry accompanied by the use of emerging new materials and even more complex shapes and structures cause increasing difficulties in design, production and maintenance of composite products. One issue is the insufficient knowledge about the cure kinetics of the composites during the production phase, which...

Well-being applications demand unobtrusive treatment methods in order to reach user acceptance. In the field of light therapy this needs to be carefully addressed because, in most cases, light treatment system size has to be significant with respect to human body scale. At the same time we observe the push to make wearable devices that deliver the...

Novel insights regarding the ability of encapsulated metal interconnections to deform due to bending are presented. Encapsulated metal interconnections are used as electric conductor or measurement system within a wide range of applications fields, e.g. biomedical, wearable, textile applications. Nevertheless the mechanical analysis remains limited...

The continuous growth of the composites industry accompanied by the use of emerging new materials and more complex shapes and structures cause increasing difficulties in design, production and maintenance of composite products. One issue is the insufficient knowledge about the cure kinetics of the composites during production, which directly result...

Thermoforming, stretchable electronics, rigid free form electronics

Conformable electronics, i.e., electronics that can be applied on curved surfaces, is demanded nowadays in place of conventional rigid printed circuit board (PCB) based electronics for a number of applications. In the field of stretchable electronics there has been a swift progress in recent years. In this paper we are presenting our contribution t...

The development and mechanical characterization of a novel technology for stretchable electronics is presented, which can be used for the realization of wearable textile electronics and biomedical implants. The stretchable devices consist of rigid or flexible component islands interconnected with stretchable meander-shaped copper conductors embedde...

SU-8 is largely used to make microfluidic molds or components, but mainly for producing high-precision and thermally stable structures. We present a versatile method that employs SU-8 as glue to perform an adhesive bonding between micro-patterned structures. More in general, this technique enables an easy assembly of microfluidic devices, which can...

Purpose In the past 15 years stretchable electronic circuits have emerged as a new technology in the domain of assembly, interconnections and sensor circuits and assembly technologies. In the meantime a wide variety of processes with the use of many different materials have been explored in this new field. The purpose of the current contribution is...

Today electronics in "wearable systems" or "smart textiles" are mainly realised on traditional interconnection substrates, like rigid printed circuit boards or mechanically flexible substrates. The electronic modules are detachable to allow cleaning and washing of the textile. In order to achieve a higher degree of integration and user comfort, a t...

In this contribution, results on technology developments are presented aiming to realize conformable electronic systems based on plastic electronics technologies. Focus of the developments is on low cost with an acceptable reliability in function of the end-application. The feasibility of this technology is demonstrated by digging into the differen...

SMI (Stretchable Molded Interconnect) technology allows for realization of PCB-like manufactured electronic systems with intrinsic ability to be bent and locally stretched multiple times. The elasticity is obtained by introduction of meandered, electrical tracks that have the ability to follow the deformation of its PDMS encapsulation without elect...

In the past 15 years, stretchable electronic circuits have emerged as a new technology in the domain of assembly, interconnections, and sensor circuit technologies. In the meantime, a wide variety of processes using many different materials have been explored in this new field. In the current contribution, we present an approach inspired by convent...

A new fabrication technology for stretchable electrical interconnections is presented. This technology can be used to connect various non-stretchable polyimide islands hosting conventional electronic components. The interconnections are realized by patterning a 200 nm thick sputter-deposited gold film into meandering horseshoe shapes, functioning a...

This paper proposes a novel concept for integrating ultrathin solar cells into modules. It is conceived as a method for fabricating solar panels starting from back-contact crystalline silicon solar cells. However, compared to the current state of the art in module manufacturing for back-contact solar cells, this novel concept aims at improvements i...

This paper discusses the optimization of a stretchable electrical interconnection between integrated circuits in terms of stretchability and fatigue lifetime. The interconnection is based on Cu stripes embedded in a polyimide-enhanced (PI-enhanced) layer. Design-of-experiment (DOE) methods and finite-element modeling were used to obtain an optimal...

A comfortable, wearable wireless ECG monitoring system is proposed. The device is realized using the combination of two proprietary advanced technologies for electronic packaging and interconnection : the UTCP (Ultra-Thin Chip Package) technology and the SMI (Stretchable Mould Interconnect) technology for elastic and stretchable circuits. Introduct...

This paper presents a summary of the modeling and technology developments for flexible and stretchable electronics. These technologies can achieve mechanically bendable and stretchable subsystems by incorporating the electronic circuit into a matrix made of a soft polymer. The base substrate used for the fabrication of flexible circuits is a unifor...

Stretchable electronic circuit boards have been developed based on three different technologies. Such substrates serve to connect rigid interposers or electronic components. The conducting traces have a meandering shape and consist of Cu-foil or screen-printed Ag-paste. These conducting traces are attached to or embedded in polyurethane, polydimeth...

In this paper, the effect of encapsulation on deformation behavior and failure mechanisms of stretchable interconnects is presented. Extensive numerical modeling is conducted for mechanical analysis of which the results are correlated with in-situ experimental observations. The numerical results reveal that by adding an encapsulation layer of vario...

A novel technology for stretchable electronics is presented which can be used for the realization of wearable textile electronics and biomedical implants. It consists of rigid or flexible component islands interconnected with stretchable meander-shaped copper conductors embedded in a stretchable polymer, e.g. PDMS. The technology uses standard PCB...

Various approaches will make wearable medical systems comfortable for the user: circuit miniaturization is important, but this approach is ideally combined with flexible and/or stretchable integration, in order to obtain conformable, randomly deformable circuitry. Imectextquoterights UTCP process (Ultra-Thin Chip Package) is an enabling technology...

In this paper, we comprehensively investigate the fatigue life and the failure modes of horseshoe-patterned stretchable interconnects, through both experimental and numerical analysis. The experimental results demonstrate that the fatigue life of a horseshoe-patterned stretchable interconnect embedded into a silicone matrix is able to resist up to...

Imec has developed a new technology to integrate and interconnect back-contact solar cells into modules, based on embedding cells in silicone on top of a glass substrate. This technology aims at an improved optical performance and reliability (through the use of silicones and low-temperature metallization). One of the additional advantages is that...

The deformation behavior and failure mechanisms of parallel-aligned, horseshoe-patterned, stretchable conductors encapsulated in a polymer substrate were investigated by numerical and experimental analyses. A design guideline for the optimal pitch between the conductors was proposed through numerical analysis, and two extreme cases—fine and coarse...

This paper presents a summary of the modeling and technology developed for flexible and stretchable electronics. The integration of ultra thin dies at package level, with thickness in the range of 20 to 30 µm, into flexible and/or stretchable materials are demonstrated as well as the design and reliability test of stretchable metal interconnections...

Purpose - The purpose of this paper is to demonstrate electromechanical properties of a new stretchable interconnect design for "fine pitch" applications in stretchable electronics. Design/methodology/approach - A patterned metal interconnect with a zigzag shape is adhered on an elastomeric substrate. In situ home-built electromechanical measuremen...

Electronics in “wearable systems” or “smart textiles” are nowadays mainly realized on traditional interconnection substrates, like rigid Printed Circuit Boards (PCB) or mechanically flexible substrates. The electronic modules are detachable to allow cleaning and washing of the textile. In order to achieve a higher degree of integration and user com...

Electronic devices capable of performing in extreme mechanical conditions such as stretching, bending, or twisting will improve biomedical and wearable systems. The required capabilities cannot be achieved with conventional building geometries, because of structural rigidity and lack of mechanical stretchability. In this article, a zigzag-patterned...

This paper presents the design and implementation of an advanced system on flexible and stretchable technology. The technology platform consists of a matrix of flexible non-stretchable functional islands linked together by a net of elastic interconnections. Several technologies have been developed and tested in the design of simplified demonstrator...

An electronic device was fabricated consisting of 2 flexible electronic circuit islands, interconnected by a 7 cm long elastic interconnection, which could be elongated for at least 50%. This interconnection was based on gold conductor tracks following a 2-D spring pattern, embedded in a biocompatible silicone elastomer. The complete device was emb...

An electronic device was fabricated consisting of 2 flexible electronic circuit islands, interconnected by a 7 cm long elastic interconnection, which could be elongated for at least 50%. This interconnection was based on gold conductor tracks following a 2-D spring pattern, embedded in a biocompatible silicone elastomer. The complete device was emb...

Purpose - The purpose of this paper is to present an update on the progress of the design and reliability of stretchable interconnections for electronic circuits. Design/methodology/approach - Finite element modelling (FEM) is used to analyse the physical behaviour of stretchable interconnects under different loading conditions. The fatigue life of...

Large area deformable macroelectronics, such as flexible display, smart bandage, electronic textile, have to withstand various modes of deformation (e.g., bending, twisting and stretching). Such electronic systems usually are composed of inorganic parts with limited deformability, and organic parts which can sustain large deformations. Because of t...

A growing need for ambient electronics in our daily life leads to higher demands from the user in the view of comfort of the electronic devices. Those devices should become invisible to the user, especially when they are embedded in clothes (e.g. in smart textiles). They should be soft, conformable and to a certain degree stretchable. Electronics f...

For user comfort and reliability reasons, electronic circuits for human body related applications should ideally be soft, elastic and stretchable, for smart textile application, but also for applications which need a high level of biocompatibility. We are developing several roll-to roll technologies using MID (Molded Interconnect Device) and low co...

For advanced body related applications, there is a need of soft, conformable, elastic, mechanical compliant and washable systems. Smart clothes for health monitoring, sport or professional protection need washable and conformable electronic systems, which can be deformed up to 20%. Implants, like monitoring sensors, or functional implants, need sof...

In this paper we review the mechanical properties and reliability results of stretchable interconnections used for electronic applications. These interconnections were produced by a Moulded Interconnect Device (MID) technology in which a specially designed metal interconnection if fully embedded with an elastic material such as polyurethane or sili...

The Musical Synchrotron is a software interface that connects wireless motion sensors to a real-time interactive environment (Pure Data, Max/MSP). In addition to the measurement of movement, the system provides audio playback and visual feedback. The Musical Synchrotron outputs a score with the degree in which synchronization with the presented mus...

This paper describes the HOP system. It consists of a wireless module built up by multiple nodes and a base station. The nodes detect acceleration of e.g. human movement. At a rate of 100 Hertz the base station collects the acceleration samples. The data can be acquired in real-time software like Pure Data and Max/MSP. The data can be used to analy...