Flip chip interconnection method applied to small camera module

Small cameras used as image storage devices have been rapidly applied to mobile information devices since the improvement of picture quality and the development of an easy picture processing method. The authors have developed a small camera module (3.6 cc, 30(W)/spl times/15(D)/spl times/8(H) mm/sup 3/; including lens unit) using two bare chip bonding methods. One is the CMOS image sensor packaging technique for fabrication on a flexible substrate by the ACP (anisotropic conductive paste) bonding method. The other is the flip chip bonding method which utilizes the advanced ACP method for a DSP (digital signal processor) chip. The new ACP enables a short resin curing time of less than six seconds. The ACP can also withstand the reflow soldering process, so that the bare chip IC and chip components can be mounted on the same substrate. By using these bare chip bonding techniques, the small camera module was realized. Regarding the ACP, its humidity absorption property was improved to obtain a high reliability. The filler content of the ACP was also controlled to obtain a high reliability. The flip chip bonding margin was confirmed to be applicable to mass production.