Pauliina Mansikkamäki

Inkjet printed System-in-Package design and manufacturing

Additive manufacturing technology using inkjet offers several improvements to electronics manufacturing compared to current non-additive masking technologies. Manufacturing processes can be made more efficient, straightforward and flexible compared to subtractive masking processes, several time-consuming and expensive steps can be omitted. Due to the additive process, material loss is minimal, because material is never removed as with etching processes. The amounts of used material and waste are smaller, which is advantageous in both productivity and environmental means. Furthermore, the additive inkjet manufacturing process is flexible allowing fast prototyping, easy design changes and personalization of products. Additive inkjet processing offers new possibilities to electronics integration, by enabling direct writing on various surfaces, and component interconnection without a specific substrate. The design and manufacturing of inkjet printed modules differs notably from the traditional way to manufacture electronics. In this study a multilayer inkjet interconnection process to integrate functional systems was demonstrated, and the issues regarding the design and manufacturing were considered.

Evaluation of Inkjet Technology for Electronic Packaging and System Integration

The main trend of the electronic packaging industry has been on increasing the packaging density and increasing the functionality, but now also the interest on flexible manufacturing has grown. In this paper, we discuss the utilization of the inkjet technology for the electronic packaging and system integration. Inkjet technology provides fully-additive non-contacting deposition method that is suitable for flexible production. In this paper, we demonstrate the capability of the inkjet technology for the printable electronics through a highly-integrated RF SiP application, which is manufactured partly by inkjet printing. The SiP contains discrete components and an ASIC with a minimum pitch of 136 mum and the size of pads is 65 mum. The width of lines/spaces is designed with a rule of 75 mum/75 mum, but also narrower lines can be printed. The width of lines depends on the properties of surface, ink, and drop volume. The properties of the surface can be manipulated with proper surface treatment. In this paper, almost 20% decrease in a diameter of drop is reported when the surface treatment is used.

Analysis of mechanical performance of silver inkjet-printed structures

We report the mechanical performance of the structure of sintered silver ink used in inkjet printing, having a particle size of 3-7 nm. Tensile adhesion pull-off testing together with the optimized related ISO and ASTM industrial standards were used. Adhesion testing of samples was performed at room temperature and in 50% relative humidity. Sintered silver ink adhesion patterns were inkjet-printed onto several substrates, i.e. PEN (Polyethylene Naphthalate), PI (Polyimide), and LCP (Liquid Crystal Polymer). To control the ink spreading surface treatment material was used and its effect on adhesion performance was investigated. To determine the effect of various sintering processes on adhesion performance, two different sintering procedures, at 250degC for 30 minutes and at 220degC for 60 minutes, were used. After the results from the initial adhesion tests had been recorded, new adhesion test samples were prepared and placed in the humidity chamber to subject them to moisture, during which the JEDEC Standard JESD22-A101-B Steady State Temperature Humidity Bias Life Test was used with a temperature of 85degC in 85% relative humidity. After this soaking, the mechanical performance of the test samples was investigated by adhesion pull-off testing and the findings noted. In addition, the test samples were subjected to tension tests using a DMA (Dynamic Mechanical Analysis) device in order to analyze the effect of the dynamic mechanical stress on them. The DMA tension tests were performed at a temperature continuously increasing from -60degC to 100degC. This testing was done on various inkjet-printed silver patterns. In this paper, the results of adhesion pull-off and of DMA testing are presented separately and the effect of each parameter on the mechanical performance of the inkjet-printed silver patterns is discussed.

Molded Substrates for Inkjet Printed Modules

Ever increasing demand for high-performance, miniaturized, low-cost, and more environmentally conscious targets set high requirements for electronics packaging and manufacturing. Digital drop-on-demand printing of materials is an interesting approach for electronics manufacturing allowing several advantages compared to subtractive methods to manufacture electronics. Additive processing by means of digital printing offers new possibilities to electronics integration, by enabling direct writing on even nonplanar surfaces, and interconnection without specific substrate for components. A module utilizing additive deposition of conductive metallic nanoparticle inks and dielectrics using inkjet printing was designed. Conventional laminate-based or ceramic interconnection substrate, i.e., printed wiring boards was not used as often in electronics modules. Chip-first modules made using a particular encapsulation method were constructed of molded substrate with embedded components and without any wiring. The molding process and the characteristics of molding material were examined using real product samples, material characterization methods, and modeling. The interconnection process using inkjettable metallic nanoparticle and dielectric inks set strict requirements for molding materials; the surface characteristics should be suitable for the inkjetting of conductive and dielectric materials. Additionally, material must withstand the harsh process conditions that include several heating cycles in relatively high temperatures for organic materials. The surface characteristics of the molding material should be adjusted to ensure good control of inkjetted fluids on a surface enabling high-yield inkjetting of fine-pitch patterns. Furthermore, the mechanical properties of molding material and molding material surface have an effect on the interconnection process yield and reliability of the inkjetted lines and interconnections. The characteristics of molded modules working as substrate for additively processed patterns is a crucial role in the manufacturing of a highly integrated printed module.

Application of wide-band material parameter extraction techniques to printable electronics characterization

Material characterization is an important part of printable electronics design, since material properties depend strongly on the manufacturing process. This paper reviews application of wide-band extraction techniques to printable electronics characterization. The extraction methods are validated using full-wave simulation data with exactly known reference for material parameters. Suitable test structures are evaluated and applied to printable electronics characterization.

Significance of Conductivity and Thickness of Thin Inkjet Printed Microstrip Lines

The effect of conductor loss of very thin lossy printed silver nano-particle traces manufactured using the printable electronics technology is studied up to 10 GHz by simulations and measurements. First, microstrip resonators are used as test structures with measurements and simulations. In addition to this, the behavior of the attenuation of microstrip lines with different conductivity value and layer thickness pairs have been studied with simulations to achieve basic guidelines for the effects of parameter variation.

Effects of 3D shapes in PWB design

Nowadays the outlook of any device can be a more important issue than the technical features inside it. Inevitably all these new and interesting features must be covered with a successfully designed package. Traditional rigid printed wiring board (PWB) can be a restriction for the designer, and, therefore, in some futuristic and novel designs, it is not used any more. A formable 3D multilayer PWB can be an answer for a faddish package without a traditional PWB. Formability brings 3D shapes into the PWB that will introduce new challenges to overcome. This paper discusses the role of 3D shapes in PWB design, and presents one solution to overcome these challenges. By designing a unique support structure for each 3D shape the inconvenient distortions can be controlled. Support structures enable the designers to use formable multilayer structures effectively, and the design freedom is one step closer.

High-frequency characterization and simulation of conductor loss in printable electronics technology

The conductor loss of very thin lossy printed silver nanoparticle traces manufactured using the printable electronics technology is characterized up to 10 GHz by simulations and measurements. Microstrip resonators are used as test structures.

Application of Thin-Film RCLG Model for the Modeling of Inkjet Printed Microstrip Lines

Conductor thickness arising from printable electronics manufacturing technology is typically of the order of a skin depth in the frequency range from the upper UHF band to the lower SHF band. Modeling these conductors using standard circuit models however yield inaccurate results whereas full-wave modeling is very time consuming. In this paper, a circuit simulation model based on the surface resistance of a thin penetrable conductor is presented. The proposed model is validated by comparison with full-wave simulation results, Comparison with a conventional circuit-simulation model shows improved accuracy in the loss calculation.

Formable multilayer PCB structure: design and technology demonstrator

Purpose – The paper aims to deal with the benefits and challenges of 3D integration of electronics and mechanics as well as the special requirements in designing a system.Design/methodology/approach – Three‐dimensional integration technology has been enabled by innovations in thermoplastic printed circuit board (PCB) materials and novel system integration. Furthermore, the integration of electronics and mechanics helps manage product creation, as design phases must be integrated and teamwork well organized. A multidisciplinary approach is another must in marketing technology, because any decision to incorporate an integrative technology in a product must be based on an understanding of the many forms of expertise involved in creating a product.Findings – With a unique copper pattern for each 3D shape, inconvenient distortions can be controlled, as dedicated copper patterns enable designers to make efficient use of formable multilayer structures and advance an extra step in freedom of design. Findings are ...