Method of multi-layer near-field electrohydraulic printing and sintering of nano-silver ink prepared by liquid phase reduction

Tiancheng Zhang,Fengli Huang,Zhiheng Yu,Chao Yang,Chengli Tang

doi:10.1063/5.0055942

Abstract

The liquid phase reduction method has a wide application prospect because of its simple equipment and low cost. However, the disadvantages, such as uneven particle size distribution and easy agglomeration of particles, make it difficult to prepare high-concentration nanoparticle ink by this method, which limits its application in the manufacture of high-resolution electronic products. This paper presents a printing and sintering process for low-concentration ink prepared by the liquid reduction method. First, the set pattern is printed by the near-field electrohydraulic printing method. At the same time as multi-layer printing, the substrate is heated by the collecting plate to accelerate the evaporation of the solvent in the printed pattern. Then, the printed multi-layer micro-conductive pattern is solidified by a hot/pressure sintering machine. This method can overcome the edge diffusion effect caused by poor ink viscosity effectively and obtain printing patterns with high thickness, high conductivity, and high resolution. The drying time of different ink layers, the pressure and temperature of hot/pressure sintering, and other parameters were studied in this paper. The electrical conductivity and reliability of the pattern with different printing layers are also analyzed, which provides a reference for the printing and sintering of low-concentration ink in the future.

Highlights

Increasing the content of silver in the conductive ink can improve the conductivity of the conductive pattern after sintering, the nanoparticles dispersed in the ink are easy to aggregate and precipitate because of the van der Waals forces and gravity, which can cause choking of the printer nozzles or non-uniform printed patterns
The results show that the resistivity of the micro-conductive pattern is only 1.89∗10−8 Ω m under the optimal sintering parameters, which is close to the resistivity of bulk silver
Measurement results are shown in Fig. 3; it is found that the simultaneous printing and drying (SPAD) method can effectively reduce the width of the printed pattern

Summary

Introduction

The liquid phase reduction method has become one of the hot spots in the preparation of nano-silver ink due to its advantages of simple equipment, convenient operation, low production cost, and easy industrialization. The nanoparticle silver ink prepared by this method has been widely used in organic diodes, field effect transistors, radio frequency identification (RFID) tags, low-cost sensors, and other flexible electronic products. The liquid reduction method needs to control the reaction temperature and precipitate silver nanoparticles out of the dispersant by dropping the reducing agent. Because the reaction temperature and the addition of the reducing agent are difficult to be controlled accurately, the particle size distribution is not uniform and easy to agglomerate. In addition, this method has the disadvantages of the low collection rate of silver powder and high impurity content, which will cause uneven printing pattern and poor electrical conductivity after sintering, restricting its application and popularization in large-scale industrial production.9 increasing the content of silver in the conductive ink can improve the conductivity of the conductive pattern after sintering, the nanoparticles dispersed in the ink are easy to aggregate and precipitate because of the van der Waals forces and gravity, which can cause choking of the printer nozzles or non-uniform printed patterns. An additive dispersant (usually a polymer) is always employed to prevent or slow down the agglomeration. the dispersant can cause an initially high resistance of the printed patterns even after the sintering treatment. it is difficult to prepare high-concentration nanoparticle ink by the liquid phase reduction method. Because the reaction temperature and the addition of the reducing agent are difficult to be controlled accurately, the particle size distribution is not uniform and easy to agglomerate.. Because the reaction temperature and the addition of the reducing agent are difficult to be controlled accurately, the particle size distribution is not uniform and easy to agglomerate.8 This method has the disadvantages of the low collection rate of silver powder and high impurity content, which will cause uneven printing pattern and poor electrical conductivity after sintering, restricting its application and popularization in large-scale industrial production.. Tang et al. prepared a low concentration multi-size silver particle (AgNPs) and silver nanorods (AgNRs) mixed ink and obtained a conductive pattern with an electrical resistivity of 14.7 Ω cm after sintering. Qin et al. studied the relationship between the number of printing layers and the electrical conductivity of Cu

Methods

Results

Conclusion