Camera Module Assembly
Camera modules, image sensors, and fingerprint sensors demand high reliability and continue to shrink in size. These issues pose challenges to their assembly processes and require high levels of precision fluid dispensing and conformal coating. In addition, their production includes several fluid types and process that require different dispensing technologies to achieve the best results.
Lens Array Production on Wafer: Wafer Level Optics (WLO)
Camera module miniaturization is fearless: tens of millimeters down to hundreds of microns. But the camera module assembly process is also destructive: wafer stacking to produce lens barrels. Thousands of lens on a wafer are stacked together with multiple wafer bonding. These lenses are produced by a molding process on wafer in which thousands of cavities on glass wafer are filled by UV-cure material and cured by UV light. The cavity filling needs very small-volume dispensing that is very quick and precise. Jetting technology for small volume dots and fast platform are essential for this application.
Image Sensor Assembly
Camera modules for mobile devices must be very thin. With flip chip technology, the image sensor is attached into the cavity interconnection frame to reduce thickness. Then the gap between image sensor and frame is filled with underfill material. Because of the cavity structure, the gap is quite tight. The dispensing challenges become small dot size, dispensing position accuracy and productivity.
Lens Barrel Attachment
Resolution is the key performance factor for camera module: the higher resolution the better picture quality. As the resolution increases, the lens barrel attachment becomes critical to align the optical path. Active alignment thus is more common: monitoring picture during lens alignment, and locking the lens barrel at the best picture with UV-cure adhesive. The UV-cure adhesive must be dispensed around the image sensor precisely in terms of location and volume. Closed-loop process control and location accuracy are required for fluid dispensing.
Flex Circuit Assembly for Camera Module
Camera modules are embedded into mobile devices with flex circuits. The flex circuits hold many components and they have to be protected from moisture with thin polymer coating. The components are very small because camera modules and flex circuits are so small. As a result, precise coating is required. For example, the 01005 capacitors have to be coated individually but conventional spray technology won't work. Jet dispensing technology addresses the challenge.
Key fluid dispensing applications to manufacture camera module assemblies:
● Cavity filling for wafer level optics
● Underfill for image sensor assembly
● Sealing for lens barrel attachment
● Precise coating for flex assembly