SMTA International Conference Proceedings


BACK END PROCESS DEVELOPMENT FOR WAFER LEVEL CHIP SCALE PACKAGING

Author: Pamela Chang
Company: Intarsia Corporation
Date Published: 9/12/1999   Conference: SMTA International


Abstract: Chip Scale Packaging (CSP) has captured the attention of every semiconductor and printed circuit board manufacturer, but relatively few CSPs are in full production. Unlike the PCB surface mount assembly process, the wafer level portion of the CSP industry (and in particular, the back end process) lacks standards. As a result, suppliers and customers have disparate requirements. This poses a unique challenge for CSP manufacturers and equipment suppliers to develop an integrated back-end-of-the-line that provides high volume and flexibility with little changeover time and low reconfiguration costs.

The back-end process we describe includes polymer coating, solder ball placement, laser marking, singulation, testing, and tape & reel. All of these are performed at the wafer level. The polymer coating process is used to define the grid array openings on the packaged devices with 0.3 mm solder balls on 0.5 mm pitch. Laser marking is incorporated with the requirement of producing alphanumeric and two-dimensional cell codes on both silicon and glass wafers. The unique requirement for singulation is to minimize the displacement of bumped die during the dicing and cleaning process. This is to minimize potential misalignment of the die during test. In order to test a diced wafer at the wafer level, we have worked with a vendor to supply a handler that can accept dicing film frames and compensate for die misalignments. Lastly, traditional tape & reel machines are not suitable for bulk packaging of small, wafer level devices. We have purchased a modified die taping/sorting machine and have designed a custom tape pocket.

All versions of the Intarsia wafer level CSP are fully surface-mount compatible and are designed to allow a wide assembly process window with existing placement equipment and technologies. Board level assembly issues unique to CSPs will be also discussed.



Members download articles for free:

Not a member yet?

What else do you get when you join SMTA? Read about all of the benefits that go along with membership.

Notice: Sharing of articles is restricted to just your immediate work group. Downloaded papers should not be stored on an external network or shared on the internet.


Back


SMTA Headquarters
6600 City West Parkway, Suite 300
Eden Prairie, MN 55344 USA

Phone +1 952.920.7682
Fax +1 952.926.1819