Direct Printing of 1-D and 2-D Electronically Conductive Structures by Molten Lead-Free Solder.

Chien-Hsun Wang,Ho-Lin Tsai,Weng-Sing Hwang

doi:10.3390/ma10010001

Abstract

This study aims to determine the effects of appropriate experimental parameters on the thermophysical properties of molten micro droplets, Sn-3Ag-0.5Cu solder balls with an average droplet diameter of 50 μm were prepared. The inkjet printing parameters of the molten micro droplets, such as the dot spacing, stage velocity and sample temperature, were optimized in the 1D and 2D printing of metallic microstructures. The impact and mergence of molten micro droplets were observed with a high-speed digital camera. The line width of each sample was then calculated using a formula over a temperature range of 30 to 70 °C. The results showed that a metallic line with a width of 55 μm can be successfully printed with dot spacing (50 μm) and the stage velocity (50 mm∙s−1) at the substrate temperature of 30 °C. The experimental results revealed that the height (from 0.63 to 0.58) and solidification contact angle (from 72° to 56°) of the metallic micro droplets decreased as the temperature of the sample increased from 30 to 70 °C. High-speed digital camera (HSDC) observations showed that the quality of the 3D micro patterns improved significantly when the droplets were deposited at 70 °C.

Highlights

Microelectromechanical system (MEMS) technologies are widely used for many applications.inkjet printing (IJP) technology is an attractive alternative to MEMS, due to its low-cost, rapid processing, and accuracy [1,2]
The main reason is that the contact region of the solidified droplet, and the results show that the molten droplet was stuck and pulled forward to micro droplet impacted on the side of the solidified droplet, and the results show that the molten droplet was stuck[19]
The results show that the impact of the droplets formed a steady line, which shows that the solidification contact angle decreases along with the Stefan number, as plotted in Figure 9b: the height and solidification contact angle decreased with the Stefan number

Summary

Introduction

Inkjet printing (IJP) technology is an attractive alternative to MEMS, due to its low-cost, rapid processing, and accuracy [1,2]. Electrical components have recently been produced for the electronics packaging industry using inkjet printing [3,4,5]. Metal micro-droplets can be printed directly, and this has become one of the most attractive processing methods in MEMS [6,7,8,9,10,11,12]. The through-silicon via (TSV) by the molten solder ejection method (MSEM) has been carried out to produce high frequency interconnections for radio frequency-microelectromechanical system (RF-MEMS) switches [16,17]

Objectives

Methods

Conclusion