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MAY 2023 I DESIGN007 MAGAZINE 63 formats along with many ancillary files, a flex or rigid-flex design should be transferred with an intelligent data format such as ODB++ or IPC-2581. Intelligent formats have evolved over time to support newer technologies such as screened resistors and capacitors, flex and rigid-flex, and other such data. Almost all PCB CAD tool providers have developed new fea- tures for designing flex and rigid-flex. ey updated their databases to support multiple stackups, new layer types, new material types, definition of bend areas, and more. However, many are laggards when it comes to exporting flex-specific data to intelligent formats. For a rigid-flex design, the design processing phase of the fabrication would benefit greatly from a transfer via intelligent data. Most layers of a rigid-flex design involve variable stackups and uncommon layer shapes—details that can- not be effectively communicated with Gerber. PCB CAD tools carefully designed new con- tent in their databases to accurately define both rigid and flexible design data. Yet for many, their ODB++ and IPC-2581 exports omit criti- cal data that would clearly aid a fabricator in expediting design processing. Without layer profile data, CAD tooling requires a user to interpret documentation to derive actual layer size or shape. Without stackup zone data, boundaries between differ- ent stackup areas have to be derived from the Orphaned Layer Content Traces, copper, board cutouts, vias, or other layer content are physically occupying space outside, or off of, the actual layer profile. Because of some PCB CAD tool limitations, layer shapes cannot be analyzed for this con- dition. Analysis must compare a layer's con- ductors against its layer profile, not the board outline. ere are many other such inter-layer depen- dency analyses that are not possible with rigid DFM analysis tools that don't recognize cover- lays, bend areas, multiple stackups, and other flexible specific data. Limited Support for Intelligent Formats Gerber remains the de facto standard for transitioning a design to fabrication. For sin- gle- or double-sided substrate flex designs, Gerber is a sufficient format to define fairly simple interconnect. However, Gerber only describes part of the process. It must be aug- mented with a combination of other files and drawings with extensive details and notes. A typical rigid-flex stackup detail presents all stackup variants across a design, not a single stackup found in rigid designs. In reality, the majority of flex fabrication packages received by manufacturers oen require clarification. Rather than providing manufacturers with multiple files of different Table 1: The type of flex and rigid-flex data that's not present in Gerber, but supported in intelligent formats

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