Abstract
As an important interconnection material in electronics, conductive silver paste has attracted much research interest in chip packaging and printed circuit board due to its predominant properties like high conductivity and flexible interconnection. In this paper, the silver nanoparticles, the silver sphere particles, and flake silver powders are fabricated by various methods. Different proportions of silver powder are selected to prepare micro-silver paste and micro-nano (mn) silver paste (fabricated by silver nanoparticles:sphere particles:flake silver powder = 1:1:1). Compared to traditional silver paste with high silver content (containing 80 wt% silver), paste in this work contains only 66.67 wt% silver. When the ratio of sphere particle to flake silver powder is 1:1, the electrical resistivity of micro-silver paste cured at 200 °C for 45 min in air is about (3.31 ± 0.73) × 10−5 Ω cm, the resistance of silver paste rises a little bit after being folded by ten times. The addition of nano-silver particles can reduce the resistivity in lower temperature curing. The folding endurance of mn silver paste is comparable to that of micro-silver paste with sphere:flake = 1:1.
Highlights
With the rapid development of micro-chip packaging and flexible printed circuit board, conditional electronic interconnection materials have been unable to meet the rising requirements in IC package and solar cell
The objective is to establish a correlation between the resistivity and the proportion ratio of multi-morphologic silver powder, we aim to explore a new way to fabricate high conductivity, low-cost silver paste
The present results indicate that the variation of resistivity of micro-silver paste is as follow: as the temperature rises, the sintering neck is generated between particles, gradually
Summary
With the rapid development of micro-chip packaging and flexible printed circuit board, conditional electronic interconnection materials have been unable to meet the rising requirements in IC package and solar cell. Point contact is formed between spherical powder fillers, while surface contact and line contact are formed between sheet powder fillers.[17] Adding appropriate spherical silver nanoparticles into the flake silver matrix can maximize the contact area and fill the gap between the conductive phase particles In this way the number of conductive network is increasing, leading to the rising of electrical conductivity. The lowest resistivity is about 8.7×10− 5 Ω·cm when the Ag plate load reaches 91%, but is only 3.7×10− 4Ωcm when the Ag plate mass percentage is reduced to 80% Another way is to use more micron silver sheets in the mixed slurry.[23] In industry, the Ag sheets is generally prepared by ball milling method, which is simple to operate and low cost. The objective is to establish a correlation between the resistivity and the proportion ratio of multi-morphologic silver powder, we aim to explore a new way to fabricate high conductivity, low-cost silver paste
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