EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: Pentoad on October 31, 2019, 07:42:16 pm
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Hello everyone, having a bit of confusion here.
I'm now ready to order some resistors and realised that there's a metric and imperial 0603 size. I don't know whether the resistors I have placed in my design are metric or imperial.
This is what they look like, the grid is 1mm.
[attachimg=1]
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Center-to-center distance for Imperial 0603 is 1.6mm; yours looks like metric 0603. EDIT - err, maybe not. You just use much larger pads than I do.
The fact that there is both an Imperial and a metric 0603 in the first place is a rant all to itself.
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0603 = metric 1608 (1.6 x .8 mm). The distance between center of pads looks like around 1.5 mm so that's got to be an imperial 0603. Metric 0603 is 0201 - that's tiny! The part would fit on one of those pads with room to spare.
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Whenever I get confused... I remember that I used to use 0805 and now I use 0603... and then I check https://en.wikipedia.org/wiki/File:SMT_sizes,_based_on_original_by_Zureks.svg (https://en.wikipedia.org/wiki/File:SMT_sizes,_based_on_original_by_Zureks.svg) and conclude that even though it is the year 2019... it is likely to be imperial.
If you measure it... and compare... http://www.resistorguide.com/resistor-sizes-and-packages/ (http://www.resistorguide.com/resistor-sizes-and-packages/)
As expected imperial.
And when I search Farnell for "0603 smd 1k" you end up finding.. "SMD Chip Resistor, 0603 [1608 Metric]" so for all intents and purposes it's probably worth only thinking in imperial sizes...
I wonder if there are people who think in metric?
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I use metric for nearly everything but in this case I had no idea what standard the component footprint was using as easyeda never specified. It makes sense now though, resistors ordered.
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I'd use imperial sizes down to 0201, then switch to metric and make sure to qualify it as such. As far as I can tell this matches equipment manufacturers as well, at least based on what I've seen at Semicon West.
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I wonder if there are people who think in metric?
I do (along with the rest of the PCB design unless doing pure through-hole for fun), and it's liberating. The metric sizes precisely encode the device size ... no conversion tables (https://www.reddit.com/r/engineering/comments/dijcde/imperial_vs_metric_industry_standards_why_are/) required. But when ordering passives, searching is more effective in imperial.
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Some years ago, I ordered capacitors in 0603 size, but didn't seen it was 0603 metric (didn't know...) and received 0603 metric, which means 0201 imperial. Very small ! I always have these capacitors, and will never use them !
Now, before ordering, I verify the unity.
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Challenge yourself. >:D
0603 soldered onto pads designed for 1608 (imperial 0603):
(https://i.redd.it/k4wo8ui4att11.jpg)
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Meh, try Imperial 0402 and metric 0402 for a challenge.