Novel flexible electrically conductive adhesives from functional epoxy, flexibilizers, micro-silver flakes and nano-silver spheres for electronic packaging

Abstract

In this study, five different flexibilizers were added into a matrix resin to improve the flexibility of electrically conductive adhesives (ECAs). The flexible ECAs were fabricated from the matrix resin and electrically conductive fillers. Their curing was fixed at 150 °C for 30 min. Of the five flexibilizers, 1,3‐propanediol bis(4‐aminobenzoate) (PBA) had the best effect on the electrical, mechanical and thermal properties of the ECAs. During curing, PBA reacted with the functional epoxy in the matrix resin. The soft ether segments in PBA were grafted into the crosslinked epoxy network to form an orderly spaced mesh structure. This led to high‐temperature stability, with the pyrolysis temperature being above 350 °C. Flexible ECAs with a 10% weight ratio of PBA in the matrix resin had the best properties. Their viscosity and bulk resistivity were the lowest. Their flexibility and electrical conductivity were the highest. They also had low storage modulus which could effectively dissipate or reduce the residual shear stress generated by the mismatch of thermal expansion coefficient between chip and substrate. Their impact strength was the lowest, and the toughening effect was so significant that the improvement was about 48% compared to ECAs. © 2013 Society of Chemical Industry

A comprehensive study of silver nanowires filled electrically conductive adhesives

“…There are two critical issues that currently prohibit ECAs from large scale applications: relatively lower conductivity and adhesive strength [1][2][3][4][5][6][7][8][9][17][18][19][20][21][22][23][24][25]. However, there are always conflicting to two fundamental properties unless the decrease of content of fillers does not cause the decrease of conductance of ECAs.…”

“…One feasible approach to this problem is the establishment of perfect conductive pathways under the low content of conductive fillers. Silver nanostructures are incorporated for the purpose of electrical conductance and adhesive strength improvement of the ECAs [1,[5][6][7][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35].…”

Influence of curing procedures on the electrical properties of epoxy-based isotropic conductive adhesives

“…[1][2][3][4][5] Compared with conventional tin-lead solders, the ECAs possess many advantages, such as environmental friendliness, finer pitch printing, lower temperature processing and more flexible and simpler processing. [3][4][5][6][7][8] However, complete replacement of soldering by ECAs is yet not possible owing to several limitations of ECAs which are mainly related to reliability aspects like limited impact resistance, unstable contact resistance, low adhesion and conductivity etc.…”

Sintering Behavior and Effect of Silver Nanowires on the Electrical Conductivity of Electrically Conductive Adhesives

“…[1][2][3][4][5][6][7][8] Among those reported composites, the isotropically conductive adhesives (ICAs) have * Authors to whom correspondence should be addressed. been investigated as a lead-free alternative in microelectronic packaging.…”

“…Compared with the mature soldering technology, there are several limitations for conductive adhesives, such as relatively lower conductivity and unstable contact resistance. [1][2][3][4][5][6][7][8] A advanced and novel ICA has been expected to possess both high electrical conductance and good adhesive strength. 1-4 9-11 But there are Delivered by Publishing Technology to: Deakin University Library IP: 184.…”