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TSSOP 38 routing problems

BigJon

Hi,

 

I've created a dozen or so through hole boards with Eagle (mostly Arduino shields), but I need to create a surface mount board. The DAC I need to use is a TSSOP 38 package (AD5348).

 

I created a custom library following an online tutorial for the DAC and copied the TSSOP 38 package for a different existing library.

 

I laid out the board (with the DAC and some op-amps) but the auto route couldnt get past about 75%.

 

I played for a while, but couldn’t get any further. So, I thought I'd test the part with a simple breakout board. I created a board with just the TSSOP 38 device, fanned out to 0.1" headers.

 

However, to my surprise, the auto route failed to route this simple board as well. See below. Why would the auto route not be able to fan out this simple board ?

 

What am I doing wrong ? Or am I expecting too much ?

 

I'm using the free version of Eagle v6.3.0 with a two layer board.

 

Thanks.

 

Jon.

 

image

 

image

Parents
  • 0

    Hi,

     

    Thanks for the all the advice. My board still won’t route and my hand routing sucks. If I upload the files, does anyone fancy telling me if it’s possible to get the auto router to work ? And what setting I need to have to do that ... ?

     

    I've got other changes / iterations I want to make to the board, and don’t want to have to keep hand routing it (badly :-)

     

    Thanks.

     

    Jon.

     

     

    image

     

    image

  • 0 in reply to BigJon

     

    On 02/02/2013 22:46, Jon Russell wrote:

    Hi,

     

    Thanks for the all the advise. My board still wont route and my hand routing sucks. If I upload the files, does anyone fancy telling me if its possible to get the quto router to work ? And what setting I need to have to do that ... ?

     

    I've got other changes / iterations I want to make to the board, and dont want to have to keep hand routing it (badly image

     

    Thanks.

     

    Jon.

      Image:DACShield-sch.png

     

      Image:DACShield-brd.png

     

     

    Learn to route by hand-understand current flow and understand good

    layout and routing practice (no 90 degree bends etc). Your not going to

    get better using the autorouter as a crutch.

     

    Even your worst effort should be better than the current autorouter

    settings.

     

    For  small boards and anything analogue hand routing wins. If you're

    going to be making small changes then these are easier and better by hand.

     

    With mixed through hole SMD designs getting the grid and tolerances

    correct is essential. Go back and re- read Warrens advice on this and

    you should be OK.

    You may need to move your parts onto a new grid to make this work. (CTRL

    left click with move  IIRC)

     

    While others have had OK success with the  autorouter I've hardly used

    it over 20 years of using Eagle but most of this has been low noise or

    high speed analogue.  Even with some very simple breakout boards I was

    not particulalry happy with autorouting and spent a lot of time tidying

    up the results.

     

      IME you are always going to need decent hand routing skills to clean

    up and autorouted board.

     

Reply
  • 0 in reply to BigJon

     

    On 02/02/2013 22:46, Jon Russell wrote:

    Hi,

     

    Thanks for the all the advise. My board still wont route and my hand routing sucks. If I upload the files, does anyone fancy telling me if its possible to get the quto router to work ? And what setting I need to have to do that ... ?

     

    I've got other changes / iterations I want to make to the board, and dont want to have to keep hand routing it (badly image

     

    Thanks.

     

    Jon.

      Image:DACShield-sch.png

     

      Image:DACShield-brd.png

     

     

    Learn to route by hand-understand current flow and understand good

    layout and routing practice (no 90 degree bends etc). Your not going to

    get better using the autorouter as a crutch.

     

    Even your worst effort should be better than the current autorouter

    settings.

     

    For  small boards and anything analogue hand routing wins. If you're

    going to be making small changes then these are easier and better by hand.

     

    With mixed through hole SMD designs getting the grid and tolerances

    correct is essential. Go back and re- read Warrens advice on this and

    you should be OK.

    You may need to move your parts onto a new grid to make this work. (CTRL

    left click with move  IIRC)

     

    While others have had OK success with the  autorouter I've hardly used

    it over 20 years of using Eagle but most of this has been low noise or

    high speed analogue.  Even with some very simple breakout boards I was

    not particulalry happy with autorouting and spent a lot of time tidying

    up the results.

     

      IME you are always going to need decent hand routing skills to clean

    up and autorouted board.

     

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