Effect of dispersant on the performance of silver conductive glue (2)

effect of 2.2 dispersants on the shear strength of silver conductive glue
Figure 2 is a comparison of the shear strength of conductive adhesives prepared with silver powder modified by different dispersants.From Figure 2, it can be seen that the conductive glue shear strength is negatively related to the length of the carbon chain of the silver powder surface dispersant, the carbon chain of positive poic acid is the shortest, the conductive glue shear strength is the largest; In conductive glue, epoxy resin is the bonding phase, which is the main bonding action. The size of the shear strength is determined by the degree of curing bonding of epoxy resin. Positive acid as a dispersant, because the carbon chain is not long enough, the surface bread cover is not complete, so the organic substation can occupy more silver powder surface, so when the conductive gel curing can obtain a higher strength. Sixteen acids and stingric acid as dispersant modified silver powder, good dispersion, density in the base polymer becomes large, the existence of a large number of silver powder destroys the continuity of the network structure, so that the shear strength is reduced. When lyicic acid is used as a dispersant, due to its double-bonding effect, the long carbon chain can not be evenly coated on the silver powder surface, the carbon chain dispersed in the organic carrier will affect the reaction of curing agent and epoxy resin, so shear strength is the lowest.
2.3 Effect of dispersants on silver conductive adhesive viscosity and tactivity index
Figure 3 is a comparison of the viscosity and tactivity index of conductive adhesives prepared with silver powder modified by different dispersants at 50 r/min.
can be seen from Figure 3, corresponding to different dispersants, tact and viscosity show similar laws. Sixteen acids and stingric acid as dispersant modified silver powder, in the conductive adhesive dispersion is better, finer particles of silver powder easily through flocculation to form a certain shear strength of the three-dimensional spatial network structure, so in the same solid content, the finer particles of silver gum easy to form a stronger spatial network structure, so the finer the silver powder particles, that is, the better the dispersion, the more obvious the system's tentacles.. 2.4 Effect of dispersants on silver conductive dispensing
Figure 4 is a dispensing comparison of conductive adhesives prepared with silver powder modified by different dispersants.can be seen from Figure 4, the droplets of the four dispersants vary from small to large: stingric acid heterosetic acid. No deformation at all when doping will cause the glue droplets too high, glue droplets overflow when bonding circuit board, so stingric acid and sixteen acid modified silver powder doping slightly worse, in addition, from the shape of the glue can be seen, stingric acid droplets, so that in the process of dosing easy to pollute the circuit board. Ionic acid and positive acid modified silver powder prepared by the conductive glue, the droplet slightly reduced, and can maintain its own shape, is the ideal state of the adhesive, so ionic acid and positive posit acid modified silver powder preparation conductive adhesive performance is better.3 conclusion
from the experimental results, with different dispersants for silver powder modified preparation of conductive glue performance is very different. Sixteen acid as a dispersant modified silver powder preparation conductive glue, the lowest volume resistivity, high shear strength, slightly less adhesive but not wire, comprehensive consideration, sixteen acid can be used as a dispersant for the preparation of conductive silver powder to make
use. Therefore, the use of a dispersant to change the silver powder can not achieve the preparation of conductive collage resistivity, shear strength and adhesiveness are the best, so the silver powder can be modified 2 times, the first layer cladding can choose sixteen acids, so that silver powder to achieve the goal of uniform dispersion, the second layer cladding can choose positive bitterness, improve the adhesive, so that it achieves better use effect..