Laser Printing of Functional Materials

3D Microfabrication, Electronics and Biomedicine

Alberto Piqué, Pere Serra

• Publisher: Wiley-VCH
• Year: 2017
• Print ISBN:
  9783527342129
• Edition: 1
• eBook ISBN:
  9783527805112
• Topic: Technology & Engineering
• Subtopic: Materials Science
• Index: Technology & Engineering

The first book on this hot topic includes such major research areas as printed electronics, sensors, biomaterials and 3D cell printing.

Well-structured and with a strong focus on applications, the text is divided in three sections with the first describing the fundamentals of laser transfer. The second provides an overview of the wide variety of materials that can be used for laser transfer processing, while the final section comprehensively discusses a number of practical uses, including printing of electronic materials, printing of 3D structures as well as large-area, high-throughput applications. The book is rounded off by a look at the future for laser printed materials.

Invaluable reading for a broad audience ranging from material developers to mechanical engineers, from academic researchers to industrial developers and for those interested in the development of micro-scale additive manufacturing techniques.

Part I
Fundamentals

Chapter 1
Introduction to Laser-Induced Transfer and Other Associated Processes

Pere Serra¹ and Alberto Piqué²

¹Universitat de Barcelona, Departament de Física Aplicada, Institute of Nanoscience and Nanotechnology, Martí i Franquès 1, 08028 Barcelona, Spain

²Materials Science and Technology Division, Code 6360, U.S. Naval Research Laboratory, 4555 Overlook Ave. SW, Washington, DC, 20375, USA

Digital manufacturing emerges as a new production paradigm that is transforming the future of the manufacturing industry on both the small and the large scale [1]. Despite that this new fabrication methodology is still far from being completely consolidated, there is little doubt now that the trend toward digitization is unstoppable and that almost no industrial field will remain immune to its influence in the next years. Thanks to the capabilities of the present-day computers and CAD software, as well as to unprecedented advances in serial production technologies, digital manufacturing makes possible a truly fast transition from an idea to its realization. This integrated approach provides in turn a new concept with a high degree of flexibility in that it allows to easily incorporate design changes into the final product. All these benefits have enabled digital manufacturing in such diverse industries as electronics, energy harvesting, packaging, decoration, textile manufacturing, medical instrumentation, or regenerative medicine.

Most digital manufacturing technologies are in fact “direct-writing” technologies, that is, they allow processing materials in a serial manner following a pattern previously recorded as a digital file [2]. The direct-writing approach makes patterning possible with high resolution and control in the flexible way just described. These technologies can be either subtractive, such as laser and water jet cutting, or additive, such as stereolithography and inkjet printing. Furthermore, they are sometimes assisted by other techniques that, instead of removing or adding new material, simply modify some of the properties of an already manufactured product, also in a digital way; laser sintering and laser curing are good examples of this.

1.1 LIFT and Its Derivatives

“Laser printing” is a quite general term that applies to a rather large set of additive direct-writing techniques whose principle of operation relies on a laser-induced transfer process: a controlled amount of material is transferred from a donor system to a receiving substrate by means of laser irradiation [3]. The relative displacement of the laser beam with respect to the receiver (and eventually the donor) makes patterning possible. The most common laser printing approach is known as laser-induced forward transfer (LIFT), a technique that works according to the described principle of operation with the donor system being a thin film and the laser source usually a pulsed laser. In more detail, an optical system focuses a pulsed laser beam onto a thin film of the donor material through its supporting substrate, which needs to be transparent to the laser radiation. Under the influence of a laser pulse, a tiny portion of the donor material is ejected toward the receiving substrate as sketched in Figure 1.1, which results in the formation of a pixel/voxel on that substrate. Through the repetition of this process at different positions in the donor/receiver system, any pattern can be produced.

Figure 1.1 Principle of operation of the LIFT technique.

The donor material in LIFT can be either solid [4, 5] or liquid [6, 7]. In the earliest versions of the technique (some of which date as far back as the mid-1960s [8–10]), the donor material was always solid. In those instances, transfers took place in the gas phase with the irradiated material completely vaporized [11] or in the liquid phase if melted (totally or partially). Accordingly, deposition occurred in the receiving substrate through recondensation of the vapor in the first case and through resolidification of the molten voxel in the second [4, 5]. Those transfer modes were especially suited for the printing of metals, for which extremely high resolutions were achieved [12]. However, it was found out later that transfer from solid films was also possible in the solid state, that is, without any phase change of the donor material. In that case, transfer proceeded through the laser-induced ejection of a “flyer” that was projected away from the donor film and toward the receiving substrate, where it landed, giving way to the formation of a voxel. That transfer mechanism not only allowed printing materials that would irreversibly change or decompose if melted or vaporized, such as complex ceramics [13], but also made possible to transfer stacks of different materials [14], especially interesting for the fabrication of multilayered devices. Even more than that, entire components such as surface-mounted devices and bare dies can be successfully transferred through LIFT [15].

LIFT can also work with liquid donor films. In this case, the material to print is previously dissolved or suspended in an ink that is transferred as a whole. The principle of operation of the technique is the same as with solid donor films (Figure 1.1), with the printing outcome now being a sessile droplet of the ink. Further evaporation of the ink solvents leads to the formation of the resulting pixel on the receiving substrate. The main difference with the LIFT of solids relies on the transfer mechanism: the ink is projected away from the donor film through a high-speed liquid jet that results from the expansion and collapse of a laser-induced cavitation bubble [16]. The LIFT of liquids is remarkably similar to inkjet printing regarding both transfer mechanism and printing outcome, but with significant advantages over it. Probably the most prominent is that LIFT presents fewer restrictions concerning the rheology of the printable inks: LIFT admits a substantially broader range of viscosities [17] and sizes of the particles loading the ink [18] compared to ...

Table of contents

• Cover
• Title Page
• Copyright
• Table of Contents
• Preface
• Part I: Fundamentals
• Part II: The Role of the Laser–Material Interaction in LIFT
• Part III: Applications
• Index
• End User License Agreement