| AVS 56th International Symposium & Exhibition | |
| Inkjet Technology: Printing, Materials Processing, and Microfluidics Fundamentals Topical Conference | Wednesday Sessions |
| Session IJ+MN+TF-WeA |
| Session: | Inkjet Printing Technology: Advances and Challenges |
| Presenter: | E.G. Hanson, Hewlett-Packard Laboratories |
| Correspondent: | Click to Email |
Thermal ink jet (TIJ) technology has a wide range of capabilities in the non-contact dispensing and printing of materials. TIJ is best known as an extremely effective and successful method for printing of documents and images on paper, using colored inks, but its applications extend far beyond ink-on-paper.
A TIJ printhead is a MEMS (Micro Electro Mechanical System) device, incorporating electronic devices and micro-machined geometrical features which are fabricated on a silicon wafer. TIJ excels in scalability and nozzle packing density. Over the past 20 years, its performance in terms of ejected ink drops per second per printhead has doubled every 18 months.
TIJ technology is extremely precise, offering volumetric control as low as 1% coefficient of variation for volumes > 0.1 microliter, and placement accuracy as low as 3 micrometers standard deviation. A wide range of materials can be ejected very effectively, including nanoparticle suspensions, pharmaceutical compounds, bioactive molecules, polymers, and adhesives. In addition to aqueous solutions, TIJ can efficiently jet numerous non-aqueous solvents.
TIJ is a drop-on-demand ink jet technique, meaning that ink drops are only ejected from nozzles when needed. In contrast, continuous ink jet technology generates a steady-state stream of ink drops, using additional components downstream of the nozzles to deflect and recirculate those drops which are not needed. Aside from TIJ, there is one other common type of drop-on-demand ink jet: piezoelectric (piezo) ink jet. In both TIJ and piezo devices, ink is ejected from nozzles when needed by applying pressure pulses to fluid-filled chambers upstream of those nozzles. These two ink jet techniques use different pressure pulse generation methods – formation of a vapor bubble inside the chamber in the case of TIJ, and mechanical deflection of a diaphragm in the case of piezo. TIJ uses much smaller chambers and generates much higher peak pressures than piezo, giving advantages in nozzle packing density, low printhead cost, and high tolerance to trapped bubbles. Piezo printheads are larger, higher cost, and more sensitive to trapped bubbles, but they do also offer longer printhead life and a wider fluid space than TIJ.
A large variety of materials deposition and dispensing applications are benefiting from the high precision and versatility of TIJ technology. The base technology of TIJ was primarily developed originally for the large market of printed ink on paper, but now these materials applications are leveraging and extending that technology base.