Fine Pitch Surface Mount Technology (PDF)

Fine pitch high lead count integrated circuit packages represent a dramatic change from the conventional methods of assembling electronic components to a printed interconnect circuit board. To some, these FPTpackages appear to bean extension of the assembly technology called surface mount or SMT. Many of us who have spent a significant amount of time developing the process and design techniques for these fine pitchpackages haveconcluded that these techniquesgobeyondthose commonly useed for SMT. In 1987 the presentauthor, convincedofthe uniqueness ofthe assembly and design demands ofthese packages, chaired ajoint committee where the members agreed to use fine pitch technology (FPT) as the defining term for these demands. The committee was unique in several ways, one being that it was the first time three U. S. standards organizations, the IPC (Lincolnwood, IL), theEIA(Washington, D. C. ),and theASTM (Philadelphia),cametogether tocreate standards before a technology was in high demand. The term fine pitch technology and its acronym FPT have since become widely accepted in the electronics industry. The knowledge of the terms and demands of FPT currently exceed the usage of FPT packaged components, but this is changing rapidly because of the size, performance, and cost savings of FPT. I have resisted several past invitations to write other technical texts. However, I feel there are important advantages and significant difficulties to be encountered with FPT.