The packaging industry is "pulling" the Printed Circuit Board (PCB) technology level in the direction of semiconductor requirements. High density PCB's are becoming commonplace in the network routers, automated test equipment, and server sectors. The need for the high density (> 150 IO/Sq.cm) is becoming a common requirement. In order to fan out the high density packages, many layers are being added as finer lines, spacing and via diameters are approaching conventional manufacturing limits. These attributes are driving changes in base materials, imaging, etching, plating, soldermask, testing processes, and registration systems. This paper examines trends in PCB attributes and utilizes a registration model and the Rayleigh distribution to predict capability for advanced registration requirements and lists some critical registration control points.
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