• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
  • Skip to footer

EE-Training

Knowledge makes you Curious

  • Home
  • Training Courses
    • Signal Integrity with Hands-On Simulation
    • Open the Black Box of Memory
  • References
    • References for Signal Integrity with Hands-On Simulation
    • References for SI Simulation Workshop
    • References for Lee Ritchey: Signal Integrity
    • References for Lee Ritchey: Stackup Design
  • Blog
  • About
    • Terms & Conditions
    • VAT Refund
    • Jobs
  • Contact
You are here: Home » Blog

Why autorouting a PCB doesn’t work?

February 14, 2012 by Rolf Ostergaard

Why don’t you use autorouting? No-one sane would hand route the internals of an ASIC. No-one sane would hand route the internals of an FPGA. Why are we constantly hand routing PC boards?

Silicon Valley is the birthplace for serious autoroutingDuring my recent visit to DesignCon in Santa Clara, CA, I took the time to research this topic a bit. I went to visit some of the folks, that used to be part of “Fine Line Design” (sold to Flextronics in 1996). A layout bureau that used to be a beta test site for the development of the Specctra autorouter. So they grew up using what is probably still the best autorouter around for basically anything they could.

Today these guys run a layout bureau doing about 400 boards per year. Not very big, but not small either. And looking at some of the bigger boards, you can’t help thinking a little autorouting help would be great.

How much is autorouted today?

So my obvious question was: Are they doing a lot of autorouting these days? Or what? Knowing where they come from, the answer may surprise you, because in reality they only use full autorouting on about 1% of their boards today. Quite a few more are partly autorouted to finish up the less difficult traces remaining after the most difficult and complex parts have been laid down by hand.

Human-powered autorouter

They also employ a much more sophisticated “human-powered autorouter”: A small team in India will routinely get assignments that are too difficult for Specctra, but still very much autorouter compatible. The human brain outsmarts the Specctra router and by using the lower cost Indian team, the net result is more and better routing for the dollar. This is a pretty interesting setup, which they claim only works after a lot of practice and effort has been put into it. I would believe that.

So why is the modern-day computerized autorouter not up for the task? The primary problem is escape/fan-out routing from modern high-density packages. Packages get denser and more complex all the time and the way autorouters work today simply does not work well in these scenarios. Even methods where you do the escape routing by hand and let the autorouter work from there are not working efficiently compared to hand routing by an experienced layout person. In order to efficiently use the autorouter, the design needs to be very homogeneous with lots of open space routing without too many or too strict constraints.

What did I learn?

What I learned from this was really two things:

  • Autorouting is not the solution for most PCB layouts today. But a “human-powered” autorouter can apparently be a great help.
  • There may be an opportunity for someone to develop a next-generation PCB autorouter that actually works on the layouts of today.

So did autorouting turn up as a big topic at DesignCon? No, not enough to get my attention at least. Maybe next year. Maybe another conference.

What is your experience with autorouters for PCB layout? And do you see future improvements on the horizon?

Filed Under: PCB Layout Tagged With: Autorouting, Layout

Stack-up Design Course

February 6, 2012 by Rolf Ostergaard

We have a brand new course on stack-up design coming to Copenhagen on June 25th. Right in the airport, so it’s easy to fly in and out the same day. Just walk to the Hilton from your flight (or train). With increased signalling speed, engineers are facing increased difficulties meeting signal quality requirements. This puts… Read more

Filed Under: Announcements

Lee Ritchey in Oslo, 2012

February 5, 2012 by Rolf Ostergaard

Lee Ritchey is one of the industry legends on high speed design. I worked with Lee back 12 years ago at 3Com in Silicon Valley and have since had the pleasure of arranging a number of 3-day signal integrity courses with Lee in Denmark, Sweden and Norway. The next training course we do with Lee… Read more

Filed Under: Announcements

Transmission line loss calculator

February 5, 2012 by Rolf Ostergaard

AWR has one of the nicer free transmission line loss calculator apps I have seen in a long time. Highly recommended. Recently I needed to approximate a cable with the following insertion loss for a 25 cm long strip: The approximation was required for an IBIS simulation in SigExplorer, so a microstrip model would be… Read more

Filed Under: Transmission Lines

Lee Ritchey in Oslo, June 20-23, 2012

February 5, 2012 by Rolf Ostergaard

3 Fantastic Days with Signal Integrity. Most modern electronics operates with digital signal switching times measured in the 100-300 ps range. At that rate the switching causes reflections on any trace longer than a few cm. The frequency content of the signals run into the GHz range. Parallel traces of just a few cm can… Read more

Filed Under: Announcements

Video: Easy PDN Measurement

February 5, 2012 by Rolf Ostergaard

A quick how-to for you: the PDN measurement video. How do you do validate bypass capacitor selection and effectiveness on the mounted PC board? This is very easy to do, and this video was created to illustrate how this is done in the lab with a Rohde & Schwarz network analyzer. It used to be… Read more

Filed Under: Power Integrity (PI/PDN)

Announcing Lee Ritchey in Oslo: June 20, 2012

February 1, 2012 by Rolf Ostergaard

We will have Lee Ritchey in Oslo in 2012 – make sure you get a seat. This is going to sell out quickly, and time is nearing. Sign up as soon as you can – just a kind recommendation.… Read more

Filed Under: Announcements

Announcing SI Training Aalborg, May 8th 2012

February 1, 2012 by Rolf Ostergaard

Next SI training in Danish will be in Aalborg on May 8th, 2012. Sign up now and secure your seat.… Read more

Filed Under: Announcements

Good PDN: Low Impedance to infinite frequency?

January 15, 2012 by Rolf Ostergaard

Signal integrity experts have taught us to design power distribution systems that can support all devices on the board with a low low impedance up to a high “target PDN frequency”. We all know, trust or believe that is important. But we soon realize that achieving low impedance from DC to infinity is impossible. So… Read more

Filed Under: Power Integrity (PI/PDN)

  • « Go to Previous Page
  • Go to page 1
  • Interim pages omitted …
  • Go to page 13
  • Go to page 14
  • Go to page 15

Get a free SI book

by Lee Ritchey (was $95),
and news from EE-Training

Search

PDNTool

Try pdntool.com and see how a 1-click optimizer might reduce your bypass caps. Read more...

Categories

Latest News

  • Online memory course: Mar 1-5, 2021
  • Crosstalk video demonstration for stripline
  • University SI Course – COVID’19 Version
  • Video: Using a Network Analyzer as a TDR
  • Video: PDN Measurement with a Network Analyzer
  • Signal Integrity w/ Hands-On NOW ONLINE May 11, 2020
  • Schmartboard breakout prototyping PCB
  • Remember: Memory course in Copenhagen Feb 5+6
  • Learn Signal Integrity in Ankara Mar 25, 2019
  • Ground bounce demonstration board

Recent User Comments

  • Rolf Ostergaard on Video: PDN Measurement with a Network Analyzer
  • Abhi on Video: PDN Measurement with a Network Analyzer
  • Rolf Ostergaard on Video: PDN Measurement with a Network Analyzer
  • Daniel S. on Video: PDN Measurement with a Network Analyzer
  • Henning E. Larsen on PDN optimizer as a free webtool

Contact

EE-Training
Rolf V. Ostergaard
+45 2684 4876
signup@ee-training.dk

QUOTES

“Training worth attending more than pays for itself in added value for you and your project”

“Training is expensive. Good training is even more expensive. No training is the most expensive.”

Rolf V. Ostergaard

M.Sc.EE, SI Consultant
Twitter: @rolfostergaard
LinkedIn: Profile
Resume: CV (pdf)

Copyright 2020. All prices shown are exclusive of VAT. General Terms & Conditions apply.
By using this site with cookies enabled in your browser you consent. Privacy policy.