1. Field of the Invention
The present invention relates to manufacturing methods and structures of a wafer level image sensor module with package structure, and more particularly, to a manufacturing method and structure of an image sensor module with an encapsulant coupled to a lateral side of the module.
2. Description of the Prior Art
Mobile devices equipped with an image retrieving unit are all the rage, and thus image retrieval is indispensable to portable electronic devices nowadays, such as notebook computers, cellular phones, and PDA. In this regard, the quality of an image retrieving unit depends on the performance of an image sensor module inside the image retrieving unit. In turn, the performance of an image sensor module extremely depends on an image sensing chip package therein.
The purpose of packaging is to prevent an image sensor module from being damaged by an external force or for an environmental reason in the course of use, and provide electrical connection between the image sensor module and an external device to thereby enable signal transmission.
However, various packaging methods in use have drawbacks or rooms for improvement as follows:
1. Space: a conventional chip-on-board (COB) package occupies relatively large space, because it comprises metal wires for use in wire bonding; a conventional COB package involves adhering an image sensing chip to a substrate or a circuit board, and thus it is difficult to reduce the total height of the package (i.e., the sum of the height of the package and the height of the substrate or circuit board); in an attempt to solve the problem with the space-consuming wire bonding structure based on COB packaging, a combination of a chip scale package structure and a wafer level lens assembly package (CSP+WLO) was put forth but found to be ineffective in reducing the total height of the module, because a chip scale package (CSP) structure requires a piece of glass for protecting a chip sensing region, and thus the total optical focal length increases with the glass thickness; also, COB packaging requires a substrate or a circuit board and therefore incurs manufacturing costs.
2. Side light leakage: all conventional packaging methods are susceptible to side light leakage and thus require an extra light mask or a masking layer coated on one side of a lens assembly; as a result, the extra light mask or coating not only incurs raw material costs but also increases the steps of a working procedure.
3. Focusing: conventional packaging methods entail performing the step of focusing by means of a focusing unit in order to focus on the image sensing chip; however, this step requires a specific apparatus and work procedure which incur costs.