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Shivvrm , 01-17-2021, 12:35 PM

I have a track of width 1.05mm connecting to a pad of width 1mm. The smd neckdown rule is set to 50% by default. What is the best practice for neckdowns in this scenario ?

robertferanec , 01-18-2021, 06:35 AM

I am not sure how others, but I do not really worry about these things. I would just connect it like that or I would use 1mm track instead of 1.05 for a little bit to go out of the pad and then I would change it to 1.05 (if that width is required). I have seen many articles and things about problems in assembly when pads are not connected properly, however we have never ever received any complains from our assembly houses even for direct plane connection to smd pads. When I will be making a video about assembly, I should ask about this.

Shivvrm , 01-18-2021, 08:56 AM

Yeah . It is actually a problem of assembly houses not the designer but still the software will give you errors when you are not following the neckdown rule intentionally due to strict requirement of the track width. SMD neckdown rules are there to ease the process for the design houses. So I think when we have no option but to violate the neckdown rule we should simply waive off the violation in software with a good reason mentioned. Sometimes we can use solid regions to get away with the neckdown rules. But still big solid regions can create an assembly problem called "Tombstone" effect.

Seems like it totally depends on the assembly houses and their technology.

Please share the video link here whenever you make it.