Pre-curable adhesive for Image Sensor Packages

The production of the CMOS and CCD sensor packages for the cellular phone has been increasing rapidly. The CMOS and CCD sensor packages are composed with the holder, glass, lens, substrate, sensor and so on. The adhesive to seal up a holder and substrate is necessary. Heat curing adhesive is usually used, and it must have curability at low temperature and enough adhesion. The projection that was arranged by a retainer of a holder and the hole which was emptied into a substrate are used to fix the place, since the position or an axis gap occurs by vibration during transportation and curing. The position or axis gap is the serious problem for an image sensor module. The image sensor packages are becoming smaller and thinner, therefore it becomes difficult to arrange space for opening a hole on a substrate. In addition, it becomes little adhesion areas, too. We suggest that the temporary adhesion is possible by UV or heat in a short period of time. By pre-fixing, it is not necessary to arrange a projection, hole and an assembly jig for fix the place. The sealing performance of the adhesive must pass in JEDEC pre-condition. So far, the conventional adhesive had only initial adhesion. However, high reliability is necessary due to the recent lead free issue and decrease of an adhesion area. Conventional adhesive doesn't have enough adhesion after high temperature re-flow (260degree.C). Conventional adhesive can't stand up to high stress during high temperature re-flow, and "delamination" occurs between holder and adhesive. It is suspected that a sealing performance is down the drain due to the occurrence of the "delamination". The repression of the "delamination" is necessary to solve this problem. The stress decrease of the adhesive and the adhesion improvement were especially completed. The soft segment was introduced to decrease the stress and "delamination" could be prevented. We have succeeded in the development of a UV or heat pre-fixing adhesive to pass in high temperature re-flow (260degree.C).