01005 (0402 Metric) Resistor Footprint

• 01005 (0402 Metric) Resistor Footprint
  Posted by Kelbit on 30 May, 2017 23:08
• Just a quick sanity check here - I'm working on a project with an HDI board and I'm heavily pressed for space. I have a lot of external pull-up/pull-down resistors around the board which are currently 0201. I would like to drop them down to 01005 to save space. We don't have an 01005 footprint in our libraries at work, so I created one with the Altium IPC compliant footprint wizard (which uses LibraryExpert as its core).  I used the dimensions & tolerances from Panasonic's 01005 ERJ series as a template, and selected the IPC least material condition (high density).
  
  The resulting footprint seems... wonky:
  
  
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  The inner green box is the component outline, and the outer box is the courtyard. Altium's IPC wizard made the pads 0.15mm wide, which is narrower then the nominal width of 0.2mm for the resistor. I would have thought the pads should be at least as wide as the resistor maximum width (0.2mm + 0.02mm). They also seem overly long at 0.3mm. It feels to me like this part will tombstone.
  
  Can anyone share the dimensions of a good high density 01005 footprint that they've used so I can compare?
• #1 Reply
  Posted by Monkeh on 30 May, 2017 23:12
• You've entered a value wrong or something is wrong with the Altium wizard.
  
  Download the standalone version and work the footprint out with it: http://www.ipc.org/html/private/landpattern/Library-Expert-2017-11.zip
• #2 Reply
  Posted by Kelbit on 30 May, 2017 23:28
• Good call! Seems to be a bug with the Altium wizard, I am using exactly the same inputs, but LibraryExpert gives me a much more sensible footprint. I will modify the footprint to use the LibraryExpert values.
  
  In case anyone comes here via Google, here's what Library Expert says an 01005 high density resistor footprint should actually look like:
  
  
  
  Time to file another Altium bug report - I think my support rep is going to start hating me real soon .
• #3 Reply
  Posted by voltsandjolts on 04 Jun, 2017 12:48
• Looks like you entered the right values in the wrong entry box.
• #4 Reply
  Posted by Fgrir on 04 Jun, 2017 16:58
• The OP hasn't entered anything wrong.  I can confirm the same result if I enter the Panasonic dimensions into the Altium IPC wizard.  I don't know that it is really a bug though - it looks to me like it is the High Density Side Fillet setting of -0.05mm that is making you uncomfortable.   That number doesn't seem to scale with the part dimensions so it gets pretty significant with such a small part.  I wonder if that number comes direct from IPC specs?
  
  You can always use Medium density or just manually change the side fillet to something you like better.