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Do you have experience with the FCC certification process? We're working on an electronic instrument, and it would be cool to hear where the pitfalls lie on the

Do you have experience with the FCC certification process? We're working on an electronic instrument, and it would be cool to hear where the pitfalls lie on the route to getting certified. Wouldn't want to spend too many trips visiting an anechoic RF chamber...

kbaker 14y ago
It really depends on how complex your product is, and how good your PCB designer is. We are getting into some decently high-speed designs (LVDS/USB) and it is definitely a learning process with every board... As far as pitfalls, they range from minor product alterations like requiring the addition of ferrite beads/elements on power lines/other wires inside the enclosure or altering component values on the board, to major alterations that require another board spin (adding extra passives like ferrites, decoupling caps, or just better PCB trace layouts), to very bad problems that require major redesign and rearchitecture of parts of the product. If you are still in the board design/prototype stage, try to add spots on data lines and high speed traces for: extra capacitors in parallel for decoupling and to target power supply ripples and harmonics, and 0 ohm resistors in series to later replace with ferrites to absorb EMI or low-value resistors to correct for trace impedance mismatches. You can always remove these when the design gets closer to production. Budget ~$1-2k extra as well if you want the testing house engineer to try various ferrites and shielding to get a design a few dB out of whack to pass while it is in their test environment. Of course, some of their recommendations may be too expensive/unworkable and some redesign is in order. Unfortunately, all of this costs time, money, and enormous amounts of energy cursing the gods of physics and RF when things go wrong... but that's part of the fun of designing new things, right? :) Great resource: http://www.murata.com/products/emicon_fun/index.html http://www.murata.com/products/emicon_fun/index.html
- tomkinstinch 14y ago
  Thank you!
follower 14y ago
Haven't had any experience myself but found a couple of resources recently that might be of interest: * "10. PCB Stackup" -- <http://www.hottconsultants.com/tips.html&#62 http://www.hottconsultants.com/tips.html> (or as PDF: <http://www.frontdoor.biz/HowToPCB/HowToPCB-extra/PCBStackups(Ott).pdf&#62 http://www.frontdoor.biz/HowToPCB/HowToPCB-extra/PCBStackups...; via the "Route" section of <http://howtopcb.net/> http://howtopcb.net/>) * "The Ten Best Ways to Maximize the Emission from Your Product" -- <http://www.hottconsultants.com/techtips/maxemission.html&#62 http://www.hottconsultants.com/techtips/maxemission.html> Both deal with the design factors that impact EMF radiation.

kbaker 14y ago

It really depends on how complex your product is, and how good your PCB designer is. We are getting into some decently high-speed designs (LVDS/USB) and it is definitely a learning process with every board... As far as pitfalls, they range from minor product alterations like requiring the addition of ferrite beads/elements on power lines/other wires inside the enclosure or altering component values on the board, to major alterations that require another board spin (adding extra passives like ferrites, decoupling caps, or just better PCB trace layouts), to very bad problems that require major redesign and rearchitecture of parts of the product. If you are still in the board design/prototype stage, try to add spots on data lines and high speed traces for: extra capacitors in parallel for decoupling and to target power supply ripples and harmonics, and 0 ohm resistors in series to later replace with ferrites to absorb EMI or low-value resistors to correct for trace impedance mismatches. You can always remove these when the design gets closer to production. Budget ~$1-2k extra as well if you want the testing house engineer to try various ferrites and shielding to get a design a few dB out of whack to pass while it is in their test environment. Of course, some of their recommendations may be too expensive/unworkable and some redesign is in order. Unfortunately, all of this costs time, money, and enormous amounts of energy cursing the gods of physics and RF when things go wrong... but that's part of the fun of designing new things, right? :) Great resource: http://www.murata.com/products/emicon_fun/index.html http://www.murata.com/products/emicon_fun/index.html

tomkinstinch 14y ago
Thank you!

follower 14y ago

Haven't had any experience myself but found a couple of resources recently that might be of interest: * "10. PCB Stackup" -- <http://www.hottconsultants.com/tips.html&#62 http://www.hottconsultants.com/tips.html> (or as PDF: <http://www.frontdoor.biz/HowToPCB/HowToPCB-extra/PCBStackups(Ott).pdf&#62 http://www.frontdoor.biz/HowToPCB/HowToPCB-extra/PCBStackups...; via the "Route" section of <http://howtopcb.net/> http://howtopcb.net/>) * "The Ten Best Ways to Maximize the Emission from Your Product" -- <http://www.hottconsultants.com/techtips/maxemission.html&#62 http://www.hottconsultants.com/techtips/maxemission.html> Both deal with the design factors that impact EMF radiation.