Member #695433

Member Since: June 28, 2015

Country: United States

  • Hello, I know this tuto has been made many years ago, however I’d like to share my recent experience with it. First, thanks for the quality of this tuto, it is awesome. I spent 2 or 3 days trying to route my 2 layers small pcb and had a hard work reaching 100%, I’m using Eagle V6.5. Nothing magic in this pcb, a PIC24 QFN 44, A 16 pins QFN chip, and 2 x TQFP 6 pins chips, some discret components SMD 0804, and an HM13 BT module, with large pins. It should fit in my PCB dimensions, 40mm x 36mm. To achieve this, I used traces width and spacing at 8 mil, and a routing grid of 0.1 mm. I always used Eagle with millimeters units when possible, as the dimensions given in the datasheet of most of the components I use are in mm, with inch mil in parenthesis. As said above, it took almost 3 days trying to reorganize the components placement, autorouting, undo, redo, etc… in order to reach 100% routing. Following your tuto in its exact expression, I kept all unit in inch mil, adjusted the traces width and spacing to 10 mil, I was surprised to see that the Eagle autorouter succeded a 100% routing at the first try. I should have read your tuto earlier, it would have saved me a lot of time and frustration.

    As a conclusion, I might be wrong but this is what I experienced, Even though the component dimensions are given in millimeters, I think it is better to keep compliant with your tuto, give all dimensions in inch mil, and, probably the most important as writtenin point 11 of your pdf document, <<Stick parts on 0.05” grid. You may not break this rule unless you have a very good reason>>.

    Eagle allows the users to enter dimensions in millimeters, and this is a supposition, but I think Eagle converts all units in inch mil prior to execute a routing task, generating loosenes with number rounding. Again, this is not certain, just my opinion.

    Hope this helps, tahnks again.

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