Comments: Designing PCBs: SMD Footprints


Comments 8 comments

  • Looking at the FT230X datasheet, I think that you mapped the pins to the QFN pinout rather than the SSOP pinout by mistake - the datasheet shows the SSOP GND pins to be 5 & 13 rather than 3 & 13 for the QFN pinout, for example. Easy enough for reader to correct but just thought I would point it out to you. Enjoyed the tutorial - thanks for doing these.

  • Eagle is a great PCB tool, but when it comes to PCB Footprints and Schematic Symbols I use SamacSys It’s saved me ever having to create libraries again. I can recommend these guys the quality is really good. Thanks for a great tutorial.

  • Hello everyone, Once I worked with Orcad and should make a footprint for an IC, one of the parameters was the height of the component. In some cases this is an important parameter. Is this parameter to be found in Eagle? Unfortunatelly, I use the free version of the Eagle (Autodesk version) and I wonder if the height parameter (if it exists) only is for the purchased versions.

    Thanks for the excellent guide, btw. It helped me to see where I made mistakes. My footprint are not generic :(. They will be from now on.

  • I am a little in doubt about the pin numbers on the SMD pads. At the time you changed the tPlace layer color to white, those numbers changed in color too. Logical conclusion: The numbers are in that layer, and they will be printed on the bare copper pads, getting in the way of soldering ?!? Is this okay? Is there some magic later in the pipeline that prevents the numbers from appearing? I see it happen in my own board too. Sometimes I had the numbers disappear when I hide the tPlace layer and sometimes not.

    • Good eyes but this should not happen: When you export the eagle files to gerber files the CAM job will ignore those numbers.

  • We can infer this from dimension E (0.236”) and dimension L ( MAX 0.05 - MIN 0.016 / 2 = 0.033”). –I think you may mean “(MAX 0.05 + MIN 0.016) / 2” :)

  • Typing a lot of numbers into Info (Properties) panes gets to be really paneful ;-) There’s a much easier way to place all the SMDs: 1. Set the grid to half of the horizontal spacing of the SMDs 2. Just before you place the first SMD, type ‘1’ (including the quotes). This will cause the SMDs to all be numbered correctly as you place them 3. Now place all the SMDs in order in the correct horizontal position, and the approximate vertical position. 4. Figure out the required vertical movement to place the SMDs where they belong. 5. Set the grid to that number. 6. Group the SMDs on the top, and move the group to the proper location. 7. Repeat for the group on the bottom. 8. Set the grid back where you normally have it.

    • That’s awesome info! Thanks for sharing.

      Manipulating the grid is definitely a great way to avoid all of that manual coordinating. I had never known about the typing 1 trick before placing the first pad. That woulda saved some time…

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