Synthesis of a nano-silver metal ink for use in thick conductive film fabrication applied on a semiconductor package.

The success of printing technology in the electronics industry primarily depends on the availability of metal printing ink. Various types of commercially available metal ink are widely used in different industries such as the solar cell, radio frequency identification (RFID) and light emitting diode (LED) industries, with limited usage in semiconductor packaging. The use of printed ink in semiconductor IC packaging is limited by several factors such as poor electrical performance and mechanical strength. Poor adhesion of the printed metal track to the epoxy molding compound is another critical factor that has caused a decline in interest in the application of printing technology to the semiconductor industry. In this study, two different groups of adhesion promoters, based on metal and polymer groups, were used to promote adhesion between the printed ink and the epoxy molding substrate. The experimental data show that silver ink with a metal oxide adhesion promoter adheres better than silver ink with a polymer adhesion promoter. This result can be explained by the hydroxyl bonding between the metal oxide promoter and the silane grouping agent on the epoxy substrate, which contributes a greater adhesion strength compared to the polymer adhesion promoter. Hypotheses of the physical and chemical functions of both adhesion promoters are described in detail

Figure 1

<p>(a) A printed line pattern on an epoxy molding compound that was printed using silver ink. (b) An FIB cross-sectional view of the thickness of the printed silver layer.</p

Cross-sectional view of the silver film on the epoxy molding compound when no adhesion promoter was used.

<p>Cross-sectional view of the silver film on the epoxy molding compound when no adhesion promoter was used.</p

Abrasion test images.

<p>(a) TiO₂ and (b) PEI inks.</p

FESEM images of two cured samples with different types of adhesion promoters (5.0%) after sintering on a hotplate at 180°C for 1 hour.

<p>FESEM images of two cured samples with different types of adhesion promoters (5.0%) after sintering on a hotplate at 180°C for 1 hour.</p

Schematic of the chemical bonding between the TiO⁻ and the silane coupling agent.

<p>Schematic of the chemical bonding between the TiO⁻ and the silane coupling agent.</p

Sample groups containing different weight percentages and types of adhesion promoter.

<p>Sample groups containing different weight percentages and types of adhesion promoter.</p

Inter-network of silver particles created from the PEI ink after the heat sintering process.

<p>Inter-network of silver particles created from the PEI ink after the heat sintering process.</p

Chemical structure of the silane coupling agent.

<p>The R-O structure represents the methoxy or ethoxy functional group. The X- structure represents organic coupling groups such as the epoxy, amino or vinyl group.</p

Mass loss versus curing temperature.

<p>After the critical curing temperature was determined, all printed samples were cured using a hotplate at 180°C for 1 hour.</p