Author: Salim Merchant Company: Adaptec Date Published: 4/28/1997
Surface Mount International
Abstract: The ever increasing trend towards miniaturization of electronics products, PCMCIA card is one such example. Three Credit Card size product mainly used as Fax modem in form of PCMCIA cards type 1 is unique because of its thickness of 3.3 millimeters. With advent of PCMCIA the challenge encountered by assemblers was to place fine pitch and ultra fine pitch devices on a thin substrate. Although many companies had been placing fine pitch, 20 mil substrate was not only new but eminently challenging for Process Engineers. The various technical issues we faced were, for example: A. When we panelized four up, the build up tolerances of pads from board to board had certain probabilities and to align stencil to this build up tolerances was a challenge. B. The designing of the fixture or transportation plate to deal with warpapge of the four up panel was a task in itself. C. Development of profile specifically for the second side when the first side had QFPs and TSOPS already loaded. There were just a few issues that we had to resolve prior to ramp up of production to high volume. This paper discusses one company’s experience from the conceptual SMT process flow of PCMCIA card to actual production quantities of 1000 cards or more per lot. The discussion covers the entire processes of SMT flow including fixturing for PCMCIA cards and panelization. This article will address the entire process beginning with Solder Paste and its disposition including Stencil design and support fixture. Placement of components by Chip Shooter and Chip Placer. The development of Reflow Profile including double sided reflow. The objective of this paper is to share author’s hands on experience in the area of Fine Pitch and Ultra Fine Pitch technology. It has been said that ‘Experience is synonymous with making and learning from mistakes’; by sharing our experience the reader (or the participant) should be able to avoid some of the errors during the development of the process of assembling PCMCIA cards.