Q: What is SHELLCASE ® CF?

A: Shellcase CF is a high-yield, low-cost wafer level technology platform for electronics that integrate optical components, such as miniaturized cameras in camera phones, digital still cameras and video camcorders. Suitable for image sensors, some types of MEMS, and other optical-based devices, Shellcase CF protects these components from contamination from the initial stage of processing and is compatible with standard wire-bond assembly processes.

An immediate application of the technology is for CMOS and CCD image sensors used in camera phones. Market research firm Techno Systems Research (TSR) forecasts the market for image sensors within camera phones is expected to experience significant growth, increasing from approximately 413 million units in 2005 to 940 million units in 2009, representing a 23% CAGR.

CF is short for COB Fabricated. As this name implies, Shellcase CF shares some similarities with Chip on Board (COB) construction, including compatibility to post processing, such as die attach and wire bonding. The critical difference between Shellcase CF and COB technology is that Shellcase CF leverages the benefits of a globally installed, low-cost wire-bond assembly base while solving the yield problems associated with COB technology, problems which become significantly exacerbated as image sensor resolutions increase and pixel sizes decrease.

Shellcase CF addresses these yield issues by protecting the image sensor from contamination from the initial stage of processing, thus enabling high assembly yields independent of the image sensor’s resolution or pixel size. The encapsulation is achieved by a glass cover, which is elevated from the silicon surface using cavity walls. The cover design leaves the bond pads exposed to allow standard wire bond assembly to the board. The protected die is then singulated and can be mounted on the board using standard mounting processes. As a result, Shellcase CF provides up to a 40% improvement in yield over existing Chip-on-Board (COB) technology used to assemble these devices today. These yield improvements translate into higher camera module assembly yield, a significant benefit for camera module manufacturers and others. Shellcase CF also provides manufacturers the flexibility to perform optical testing at the most favorable point of the assembly flow, as defined by their specific requirements and manufacturing environment.

Q: What is the key difference between Tessera’s Shellcase CF technology and a Chip on Board (COB) solution?

A : Shellcase CF encapsulates the die within a glass lid in the first stage of wafer back-end processing, thereby keeping the device protected from potential contaminants in subsequent process stages.

Consequently, Shellcase CF is largely indifferent to the composition and/or type of device it encapsulates. Shellcase CF provides up to a 40% improvement in yield over COB technology. Yield improvements are most notable as imager resolution increases and pixel size decreases. As yield improves, the cost per imager significantly declines.

Q: Describe the development process for this product?

A: Shellcase CF is the first product developed by Tessera Israel, which is Tessera’s wafer level center of excellence in Jerusalem, Israel. Tessera Israel was formed through Tessera’s purchase of technology assets from Shellcase Ltd. Tessera’s Shellcase CF technology builds on the foundations of the Shellcase technology family, which leverages a mature, proven, and broadly adopted wafer level packaging platform pervasively used for image sensors today.

A: A glass cover encapsulates the active area of the imager. The glass is elevated from the active area of the sensor using cavity walls bonded to the silicon surface. Bond pads are left exposed for wire bonding at a later stage .

Q: What are the potential markets for Shellcase CF?

A: The primary market for ShellcaseCF today is camera phones . Other applications include digital still cameras, video camcorders, PDAs and laptops. Shellcase CF is also suitable for some types of MEMS and other optical-based devices.

Q: Can Shellcase CF handle image sensors which incorporate micro lenses on top of the pixel array?

A: Yes, this is in fact a key application for Shellcase CF technology – using the cavity walls, the glass encapsulating the imager is elevated above the front side of the die, providing the required space for the micro lenses.

Q: Can Shellcase CF address issues associated with optical test?

A: Shellcase CF provides manufacturers the flexibility to perform optical testing at the most favorable point of the assembly flow, as defined by their specific requirements and manufacturing environment.

Q: What are the key advantages of Shellcase CF?

A: Shellcase CF:

• Protects the die against particles from the initial stage of processing
• Leverages COB assembly processes
• Enables full optical testing at the wafer level
• Minimizes clean room infrastructure requirements
• Benefits from the economics of wafer level assembly including testing
• Is highly robust and small in size
• Delivers high yield, independent of imager resolution or pixel size, driving down the cost per imager

Q: How do I license this technology?

A: Shellcase CF technology is currently available for licensing. Prototype samples for evaluation are also available.

Q: Is Shellcase CF compatible with RoHS?

A: Yes. Moreover, Shellcase CF uses only materials commonly used in the industry.

Q: Is reliability data available for Shellcase CF?

A: The Shellcase CF platform is very robust and durable. It meets the following reliability specifications:

If you are interested in learning more, please contact us at info@tessera.com.