While an online Gerber viewer should simplify the visualization of PCB layouts, its performance on complex PCB designs may vary widely depending on processing capabilities and other implemented features. Gerber viewers generally support the RS-274X—PCB design data is typically exchanged in this standard file format, however some difficult designs with multiple layers, a dense layout of traces and components are sometimes not read properly. While most online Gerber viewers can handle up to 10 or 12 layers without breaking a sweat, more complicated/multiple layer designs (particularly any that exceed 20 layers or include complex routing) will need advanced viewing capabilities.
When high-density interconnects (HDI) are used and components are spaced within 0.5mm or less of each other — as in many advanced PCB designs — accurate scaling and true-to-size drawings are essential for clarity in layer stacks. Premium Online Gerber Viewers are tailored to tackle these complexities, offering zoom capabilities and a toggle option for layers so that designers can take a very close look at each layer. A clear example of this kind of tool is NextPCBs viewer which supports complex layouts with visibility on detailed tracks and complex circuits.
The best high-performance online Gerber viewers use vector-based graphics rather than rastered images to cope with complex designs, so you can zoom in without losing image quality. Such accuracy are important when looking at designs that embed traces smaller than 5 mil (0.127 mm) – as those you find in high frequency circuits where signal integrity is essential. Advanced viewers also enable solder mask layer inspection and drill file extraction which is very important to verify alignment in multi-layer PCBs.
Many professionals in the industry believe that Gerber viewers found on the web provide a great first pass input however may not be as thorough in review to software based edge data inspection. Nathan McCorkle, a senior engineer at Cadence Design Systems states that “Online viewers are getting better, but they do not always have the real-time interactivity that we need for complex designs — particularly those with advanced vias and stacked layers.” On the other hand, online Gerber viewers are not far behind in terms of functionality and have started coming up with new features like automated DFM checks which can check for issues such as closeness of traces from each other, shorts between them and alignment of holes to name a few.
If your designs are complex and require advanced file types like ODB++ and IPC-2581 that contain more than just the Gerber format, then ensuring it has support for them is a major consideration when selecting an online Gerber viewer. Such files have a lower level of detail compared to the traditional PCB design files but are receiving growing support by on-line tools.
To conclude, even though an online gerber viewer can handle numerous features of complicated PCB designs, its success comes down to the individual tool. Most simple designs work fine with the lower end viewers on the web, more complex layouts can be made easier to read using a viewer that supports layer separation, high res zoom and advanced error checking options. On its own, it was suggested that online viewers serve as a basic first step in an overall design verification process which should then be followed by more specialized viewing software for the final review of detailed, multi-layer PCBs.