Tessera exploits wafer-level technology to shrink mobile-phone cameras

15 Jun 2007

Manufacturing thousands of lenses on a wafer will reduce the size and cost of camera modules for mobile applications.

Tessera's new OptiML Wafer Level Camera (WLC) process is able to manufacture thousands of lenses on a semiconductor wafer at the same time. Multiple lens wafers are aligned and bonded at the wafer level, and are then diced into individual lens modules. Each module is finally mounted on top of a packaged image sensor to form the optical element of the camera.

Wafer-scale lens

According to Tessera, the result is simplified assembly and a cost saving of up to 30% for the camera's optical component. It also reduces the height of camera modules, by eliminating the need for plastic molds and flex-lead cables. The height of an OptiML VGA implementation is claimed to be 2.5 mm, compared to the 3.5 - 5 mm found in conventional modules.

"We believe wafer-level camera manufacturing technology is the most viable path to highly integrated, low-cost optics for consumer and other electronics," said Bruce McWilliams, Tessera CEO.

A working prototype module will be shown at the end of the next quarter, and Mike Feldman, Tessera CTO, said that wafer-level cameras will be incorporated into handsets by the end of 2008. "We are in active discussions with key members in the camera phone supply chain," he said.

The lenses are built using reflow-compatible materials, so the camera module can be mounted directly onto the phone board using the same reflow process used to assemble the other electronics. This reduces labor costs, part count and cycle time when incorporating the camera into the phone.

For fixed-focus applications, typically VGA to 2 megapixel-resolution camera phones, the accuracy with which the lenses are bonded and stacked removes the need for manual focus adjustment of the optical elements. For 2 megapixel cameras and above, auto focus and digital optical zoom can be integrated using technology acquired when Tessera bought Israeli company Eyesquad.

Tessera's other recent activity in the consumer optics sector has seen the company acquire wafer-level packaging developer Shellcase, also based in Israel, and micro-optics specialist Digital Optics, US. "With our acquisitions of Shellcase, Digital Optics and Eyesquad, we have assembled what we believe to be the strongest portfolio of camera optic technologies in the marketplace," said McWilliams.

According to market analysts Gartner Dataquest, the mobile phone camera market is estimated to grow from 660 million units in 2006 to over 1.1 billion units in 2011. The challenge the industry faces is to integrate greater levels of functionality in smaller form factors at acceptable levels of cost. This new wafer-level approach to miniaturization provides an innovative solution for meeting these objectives.