I am bumping this old thread because it's a topic I have been thinking about for quite some time...
To understand why Rogers PCB (or Taconic, or whatever RF materials) are so expensive compared with today's chinese FR4 boards one should see why the latter have become so dead cheap:
- Pooling. With the hundreds of Gerbers coming in each day, they can fill up their production panels. They might achieve an efficiency (surface turned into Boards / panel area) of 80% or more.
- big panels (24 * 36" or more), state of the art equipment, standardized, high yield process.
- very high degree of automatization.
- running several identical panels that are drilled together (drilling is the most time consuming production step)
- material itself is cheap.
In comparison, "special" boards, which includes RF Materials:
- no pooling. They run a small panel with just one customer's design. Efficiency may be 30%, i.e. 70% of the expensive material ends up in the trash, and production costs have to be paid by the remaining 30%.
- small panels (12 * 18"), 1/4 of the "big" FR4 panels. They are either run through a special, smaller prototyping line, or with an adaptor frame through the big one, where they occupy the same space/time slot as a large FR4 panel.
- one panel instead of 3 in the drilling machine. even more expensive machine time per board.
- the material itself is more expensive, but that, IMHO, explains only a small part of the higher price.
The key factor for cheap prototype PCB's is pooling. That only works, if the manufacturer collects enough orders to fill up a panel during his guaranteed turnaround time (- the one day really needed for production). So, quick and cheap are mutual exclusive. On the other side, this opens a possible way to reasonably priced RF boards:
- EITHER convince one of the chinese manufacturers that there is a market for an RF PCB pool, offering only selected materials / thicknesses, and accepting significantly longer turnaround times than with standard FR4
- OR convince somebody like Aisler, who's business model is pooling and having the panels manufactured by third parties, of the same thing
- OR somebody sets up such a pooling service
The main question is, which turnaround time will be accepted. A hobbyist will probably have no problem waiting 4 weeks if he gets his little Rogers board for 20 $ instead of 200. For a business, that may be 3 1/2 weeks too long.