Post B7MQVkDrg2KlDLQQKW by niconiconi@mk.absturztau.be
(DIR) More posts by niconiconi@mk.absturztau.be
(DIR) Post #B7MQVkDrg2KlDLQQKW by niconiconi@mk.absturztau.be
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@cccpresser@chaos.social PCBs are still sold by mils, with a 10 mil/10 mil board being the de-facto cheap class. This is one of the other headaches in electronics: metric feature sizes are always slightly smaller than the imperial feature sizes. If the board design is metric, you're forced to move one step up in the pricing hierarchy, because your metric features exceed the imperial minimal by a few micrometers! In this case, the 0.25 mm trace is under the 10 mil minimum by being 4 micrometers too short!
(DIR) Post #B7NvUY6CYfj13qi7RQ by fullywoolly@mastodon.social
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@niconiconi @cccpresser had no idea about the diff between mils and metric. I figured if you kept to the manufacturers stated feature size, everything would be ok.
(DIR) Post #B7NvUYHtrB5Be8BSfw by niconiconi@mk.absturztau.be
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@fullywoolly@mastodon.social @cccpresser@chaos.social The problem is pricing. The preferred metric and imperial feature sizes are not interchangeable. If they mismatch (e.g. submit a metric-based design to a fab with imperial design rules), you're forced to pay more for stricter tolerance when it's in reality just a rounding error (after converting millimeters to mils, you get 5.9 mil instead of the preferred minimum of 6 mil).
(DIR) Post #B7NvlBxM8ZqVJGVcvo by sconient@techhub.social
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@niconiconi What are the manufacturing tolerances? Would shrinking the cap pad sizes by 2 microns really make a difference?
(DIR) Post #B7NvmwzakBOrTlOS36 by niconiconi@mk.absturztau.be
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@sconient@techhub.social No, it doesn't. It's a common cheap trick used everywhere. But when you deviate from the standard IPC footprints, part of the blame shifts to you.