When is an 0201 Not an 0201?

I’m working on a special project here that involves some 0402 LEDs and 0201 resistors. When doing such a thing, you should always check the footprint you’re using against the datasheet. When using extra small parts, like this, I recommend making a custom footprint unless the one you picked is exact, and I meanĀ exact. There just isn’t an margin for error at these geometries.

Take a look at the table on the right. The dimensions are in mm. Spot anything a bit off? Counter to most datasheets, the sizes listed in the “Type” column are metric sizes. At DigiKey, the package was listed as “0201 (0603 Metric).” I see that all the time, but for some reason, most datasheets show the package name in US size while listing the dimensions in metric.

The first table was at the front of this data sheet (page 5). The second table was on page 35 – the opposite end of the datasheet.

We do occasionally get boards with metric size pads for a US-size part, or vice versa. Sometimes we can make it fit, but not always. Bottom line, is to check and double-check. I caught this one because the dimension 0.54 mm is about 21 mils, too small for an 0402. That, and the fact that the table doesn’t list an 0201 size.

Duane Benson
Is it Bigfoot or Sasquatch?

http://blog.screamingcircuits.com/

About Duane

Duane is the Web Marketing Manager for Screaming Circuits, an EMS company based in Canby, Oregon. He blogs regularly on matters ranging from circuit board design and assembly to general industry observations.
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One Response to When is an 0201 Not an 0201?

  1. Robert M. Wolfe says:

    Duane,
    It’s not just the fact that you need to be very careful & triple check which unit system these chip parts are being defined in.
    With Case codes being defined for Caps as 1206 whether chip or molded body the body dimensions are 1206 however if it is a molded tant I feel the land pattern should be different. If the person doing schematic symbols defines case as 1206 and there isn’t anything else jumping out at you to look closer you could use a std 1206 chip pattern. It will work but certainly not optimal for the Tant molded body lead arrangement.
    Yes a little less confusing because when you see the schematic as a polarized symbol is a good clue it’s not a regular 1206 but still leaves room for errors.
    Bob

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