IWLPC (Wafer-Level Packaging) Conference Proceedings


Authors: C.Brubaker and T. Matthias et al.
Company: E.V. Group, Inc. and The Dow Chemical Co.
Date Published: 9/17/2007   Conference: IWLPC (Wafer-Level Packaging)

Abstract: Since its inception, Benzocyclobutene (BCB – marketed as Cyclotene® Advanced Electronics Resin by The Dow Chemical Company) has been seen as a valuable spin-on polymer dielectric for both passivation and redistribution layers for wafer-level chip-scale packaging processes. However, in the years since, this material has also been put to use for a variety of other purposes. This paper proposes to describe many of the state-of-the-art processing uses for BCB.

One manner in which BCB is being used above and beyond its initial intent is as a bonding adhesive. BCB has been used in two manners. First, with patterned layers to define a gasket or seal ring to act as the bonding layer to create a sealed package. Second, in an unpatterned manner, such as to perform three-dimensional interconnect (3D Interconnect) bonds that allow the circuitry to two patterned devices to act in concert.

BCB is also being applied via spin and spray coating techniques to allow utilization in a number of additional areas. One such is to enable underfill of suspended structures such as air-bridges in an efficient manner. A second combines the use of spray coating and wafer bonding to allow sealing of etched cavities in place over mechanically critical elements such as MEMS devices (where the device wafer cannot be coated, and spin coating of the wafer with etched cavities is difficult).

KEYWORDS: BCB, Wafer Bonding, Spray Coating, Underfill, 3D Interconnect

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