More IPC Results

Volume 1, Issue 1

Book-to-bill ratios and growth rates for rigid PCBs and flexible circuits combined are heavily affected by the rigid PCB segment. Rigid PCBs represent an estimated 91 percent of the current PCB industry in North America, according to IPC's World PCB Production and Laminate Market Report.

Bare Circuits Versus Assembly
Flexible circuit sales typically include value-added services such as assembly, in addition to the bare flex circuits. In November, the flexible circuit manufacturers in IPC's survey sample indicated that bare circuits accounted for approximately 73 percent of their shipment value reported for the month. Assembly and other services make up a large and growing segment of flexible circuit producers' businesses. This figure is also sensitive to changes in the survey sample, which may occur at the beginning of each calendar year.
Interpreting the Data
Year-on-year and year-to-date growth rates provide the most meaningful view of industry growth. Month-to-month comparisons should be made with caution as they may reflect cyclical effects. Because bookings tend to be more volatile than shipments, changes in the book-to-bill ratios from month to month may not be significant unless a trend of three consecutive months or more is apparent. It is also important to consider changes in bookings and shipments to understand what is driving changes in the book-to-bill ratio.

The information in IPC's monthly PCB industry statistics is based on data provided by a representative sample of both rigid and flexible PCB manufacturers in the USA and Canada. IPC publishes the PCB Book-to-Bill Ratio and the PCB Statistical Program Report each month.

Statistics for the previous month are not available until the last week of the following month.

www.IPC.org

 

Designers are warned by management, project engineers etc... That the design of a flex circuit is different and is asked to consult with the fabricator or in some cases simply want to offload the design responsibilities to the supplier. It’s not that difficult and adding this knowledge to your experience tool box isn’t as daunting a task as it may seem.

Similarities and differences

                 PCB design rules are well known. There are minimum hole sizes, minimum trace width, minimum space between traces and pads. We know to keep copper geometries a certain distance away from the routed edges. We know about hole size and outline tolerances, copper and board thicknesses and myriad other specifications that we don’t even think about any more because it has become an inherent part of our thought process.

Flex circuit design rules are very similar!  We must pay attention to all of the same issues, minimum hole sizes, minimum trace/space specifications, distance to edge and tolerances.

First let’s discuss the fabrication process. Traditional PCBs and flex are fabricated in much the same way for the first several steps. The flex material, typically copper clad polyimide, is allocated, drilled, plated, imaged, developed and etched just as printed circuit boards are. The next step however is where the changes occur. The panels must be baked as are PCBs to remove moisture from the wet processes, then however where a PCB would go to a solder mask station, flex circuits go to a cover layer station.

 See More Flex vs. PCB on last page.

Flex vs. PCB

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