Placement accuracy for components placed in Isotropic Conductive Adhesive

When components are placed in solder paste or components with bumps are placed with flux, the position of the component is corrected during reflow, due to the self-alignment effect of the fluid solder. Also when components are placed in solder paste, the solder paste is pressed away from underneath the component. During reflow, the solder paste which is pressed away, flows back towards the component. Isotropic Conductive Adhesive is an alternative for solder in electronic component mounting. When components are placed in Isotropic Conductive Adhesive ( ICA) the ICA is also pressed away from underneath the component. During curing, the ICA which is pressed away doesn’t flow back and there is no self alignment effect of the components. There will be no correction during curing. For the choice of equipment it is important to know the maximum allowed placement accuracy for components placed in ICA.

0402 Components and FCs were placed on FR4 boards with the ACM. The 0402 components were placed with an increasing offset in both X and Y direction. After curing the ICA, a four point measurement was done to measure the contact resistance at 0-hour. The FCs were placed with an increasing offset in only the X-direction. After curing, on four positions per FC a four point measurement was done at 0-hour.

To read the full article, click here