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106 DESIGN007 MAGAZINE I APRIL 2021 Article by Dave Lackey and Anaya Vardya AMERICAN STANDARD CIRCUITS e design process is arguably the most important part of the flex circuit procurement process. e decisions made in the design pro- cess will have a lasting impact, for better or worse, throughout the manufacturing cycle. In advance of providing important details about the actual construction of the flex circuit, it is of value to provide some sort of understanding of the expected use environment for the fin- ished product. e electronics industry serves several dif- ferent markets that do not always share the same product acceptability or reliability expectations. For this reason, the electronics industry, through IPC and other standards organizations, has developed a classification system that specifies what is expected of prod- ucts for different classes. e system of clas- sification is not intended to be a measure of quality. Rather, quality is a matter of confor- mance to a set of established requirements for a product in a given application. erefore, quality products can be created in each of the classifications within the system. It is generally accepted that there are three classes of prod- uct. ese have been defined by IPC standards as follows: • Class 1—Consumer products and products for non-critical applications where cost is normally the primary driver. • Class 2—Higher-order products in terms of quality and reliability expectations, including telecommunica- tions, computers and general industrial. • Class 3—High-reliability applications including military, aerospace, automotive, and medical products. By defining the class of the product being designed, the purchaser is letting the manu- facturer know what added controls to apply to the manufacturing process and the level of care they will need in the inspection process to BOOK EXCERPT: The Printed Circuit Designer's Guide to… Flex and Rigid-Flex Fundamentals Chapter 2: Designing Flex Circuits for First-Pass Success