Photoformed Thick Film Materials and Their Application to Fine Feature Circuitry

摘要

Increased demands for small circuit feature sizes have provided incentives to the development of new photoformable thick film compositions. Previously the limited applicability of such materials meant that only gold (Au) and in some cases silver (Ag) based compositions were developed. Now, with strong interest being shown by automotive and wireless markets coupled with those who want to replace thin film with a lower cost process, activity in photoformable materials development has become very significant and the definition of what is needed and its priorities are becoming clearer. This paper describes the characteristics of some newly developed photoformable materials, including Au, Ag, and Ag-Pt (platinum) conductors, capable of 30μm lines on a 60μm pitch, a robust Ag compatible dielectric material, based on QM44 technology, capable of forming vias as small as 50μm on a 100μm pitch, and blendable low ohm resistors also capable of very small sizes (50μm 50μm). These materials have application in a wide variety of high density interconnect circuits, including automotive ECU'S, bump-on-via multichip packages and 50Ω transmission lines in wireless applications. Details of the properties, capabilities and processing of the materials are discussed. Future planned developments for photoformable compositions over the next few years are also outlined and presented in the form of a roadmap.