银浆中玻璃相对银铝接触电阻及接触界面的影响研究-张杰峰

华东理工大学 -材料科学与工程学院 School of Materials Science and Engineering, East China University of Science and Technology 银浆中玻璃相对银铝接触电阻及接触界面的影响研究 张杰峰 Effect of glass phase in Ag paste on Ag/Al contact resistance and contact interface 1.Background The interface between Ag electrode and Al electrode The contact formation between Ag and Al electrode import Ag/Al contact resistance, which have an important effect on cell property. T. Urban, M. Heimann, A. Schmid, A. Mette, J. Heitmann, Energy Procedia 2015, 77, 420. conductive phase for electron transport and collection Ag powder inorganic binder phase to determine the adhesion strength and contact resistance between Ag and Al electrode Glass frit disperse phase allowing smooth printing of the Ag paste and obtaining a good aspect ratio of grids Organic phase 1.Background This work attempted to investigate the effect of glass phase in Ag paste on the contact resistance between Ag and Al electrode. 2.Experiment The preparation of glass frit The preparation of Ag paste The preparation of electrode 2.Experiment The test of DSC curve and glass transition temperature of glass frit were carried out with differential scanning calorimeter (DSC, TA, Q20) in air and a heating rate of 10 °C/min Thermal properties The contact resistance between Ag and Al electrode was measured using a digital micro-ohmmeter Ag/Al contact resistance Field-emission scanning electron microscopy (FE-SEM, Hitachi, S-4800) was employed to observe cross-sectional microstructure between Ag and Al electrode and the surface morphology of sintered Ag electrode Morphology characterization Paste Glass frit(wt%) Ag powder (wt%) Organic phase(wt%) P-1 2%G-1 60% 38% P-2 2%G-2 60% 38% The P-1, P-2 paste were prepared with G-1 , G-2 glass frit and sintered at 800℃ .  The Ag/Al contact resistance of P-1 was greater than that of P-2.  Glass frit had an important effect on Ag/Al contact resistance. 3.Results and discussion The Ag/Al contact resistance between Ag electrode and Al electrode 3.Results and discussion (a1),(a2) Low and high resolution corss-sectional SEM image of P-1 electrode and Al electrode (b1),(b2) Low and high resolution corss-sectional SEM image of P-2 electrode and Al electrode SEM was employed to observe the interface of Ag and Al electrode co-sintered at 800℃ , and the interaction between glass and Al was investigated by spinning and sintering glass on Al foil at 800℃ and sintering the mixture of glass and Al powder at 800℃ . (c1) The interaction between G-1 glass frit and Al foil (c2) Cross-sectional SEM image between G-1 glass frit and Al powder (d1) The interaction between G-2 glass frit and Al foil (d2) Cross-sectional SEM image between G-2 glass frit and Al powder  G-1 glass was easier to wrap Al particles, hindering the Ag/Al contact formation and causing high Ag/Al contact resistance.  G-2 glass had a poor infiltration with Al particles, thus a better Ag/Al contact was formed, causing low Ag/Al contact resistance. (a1),(a2) Surface morphology of sintered P-1 electrode (b1),(b2) Surface morphology of sintered P-2 electrode 3.Results and discussion Tg of glass was measured and surface morphology of sintered Ag electrode (800℃ ) was observed with SEM. DSC curve of glass frit  Low-Tg glass (G-1) flowed easily to the surface of Ag metallization electrode to hinder the Ag/Al contact formation, causing high Ag/Al contact resistance.  High-Tg glass (G-2) slowly flowed, thus Ag and Al electrode had a better contact, causing low Ag/Al contact resistance. Paste Glass frit(wt%) Agpowder(wt%) Organic phase(wt%) PX-0 -- 62% 38% PX-1 0.8%G-2 61.2% 38% PX-2 2%G-2 60% 38% PX-3 4%G-2 58% 38% 3.Results and discussion PX pastes contained different glass frit content were prepared and sintered at 800℃ .  The Ag/Al contact resistance was decreased with the increase of glass content in Ag paste. The Ag/Al contact resistance between Ag electrode and Al electrode 3.Results and discussion SEM was employed to observe the interface between Ag electrode and Al electrode co-sintered at 800℃ , and the interaction between glass frit and Ag powder, glass frit and Al powder, glass frit and Ag powder and Al powder sintered at 800℃ . (a) Corss-sectional SEM image of PX-0 and Al electrode (b) Corss-sectional SEM image of PX-1 and Al electrode (c) Corss-sectional SEM image of PX-2 and Al electrode (d) Corss-sectional SEM image of PX-3 and Al electrode (e) The interaction between G-2 glass frit and Ag powder (f) The interaction between G-2 glass frit and Al powder (g) The interaction between G-2 glass frit and Ag powder and Al powder  The thickness of AgAl alloy was decreased and the amounts of Ag precipitates in the inter- miscible zone were increased with the increase of glass content in Ag paste.  The resistance of AgAl alloy was greater than Ag, and Ag precipitates could act as charge storage center allowing the electron hopping and improving the electrical conductivity, thus the Ag/Al contact resistance was decreased with the increase of glass content in Ag paste. 3.Results and discussion (a) Surface morphology of sintered PX-0 electrode (b) Surface morphology of sintered PX-1 electrode (c) Surface morphology of sintered PX-2 electrode (d) Surface morphology of sintered PX-3 electrode SEM was employed to observe the surface morphology of sintered Ag electrode (800℃).  The concentration and average size of Ag precipitates which allow the electron hopping were increased with the increase of glass content in Ag paste.  Thus the Ag/Al contact resistance was decreased with the increase of glass content in Ag paste. 4.Conclusion  When the glass phase had a low Tg, Tm, and a stronger wettability with aluminum, molted glass was easier to flow to the surface of sintered silver. The surface glass wrapped and infiltrated aluminum powders, causing a non-conductive glass layer of aluminum particles, thus hindering the current transmission from the silver to aluminum and resulting a high contact resistance value.  If the glass frit had a high Tg, Tm, and light wettability with aluminum, the content of glass which flowed to the surface of the sintered silver was low. Therefore, the Ag/Al interface could have a good contact formation, finally causing a lower contact resistance.  High content glass in Ag paste was beneficial for the formation of Ag precipitation which allowed the electron hopping and improved the electrical conductivity, thus the Ag/Al contact resistance was decreased with the increase of glass content in Ag paste. Thanks！