Re: soldering components on larger sized pads

Joel Koltner wrote:
"Joerg" <notthisjoergsch@xxxxxxxxxxxxxxxxxxxxx> wrote in message news:vGDqk.34911$co7.7078@xxxxxxxxxxxxxxxxxxxxxxx
I also tell him every time not to use the default trace width which is usually 8mils or 10mils. No reason for that and it costs reliability.

If you have the space for it, I'd agree there's no reason for it. As for costing reliability though... is this really true anymore? With the "standard spec" trace size usually being 6mils these days, I wouldn't imagine there's much measurable difference between the reliability of 10mil traces vs. e.g., 25mils?


Well, I have seen more grief in this area than I cared to see. The thinner a trace the easier it breaks, especially with this dreaded habit of not rounding corners and not doing trea-drop pad entried. That's usually where stress breaks happen. Ok, most of the stuff I design gets quite a beating in the field.

Thing is, when there is enough space why default to the skinniest trace? Just to make the autorouter happy?

The worst stuff I've seen is when designers didn't realize that there was more current flowing than the trace could handle. One of the units I got for an investigation was still emitting such a stench that I had to close the lab door and open a window.


I asked the "via in pad" question because I've seen it being suggested more and more as a means of reducing parasitics a bit and packing a bit more onto a given PCB, which suggests that assemblers might be getting better at. I've used them myself (with an assembly house that said they were fine), but it was just run-of-the-mill commercial products, not medical gear.


Technically it can be ok but is messes with the thermal properties of the pad and it ain't all flat anymore. The only time I ever did that was where I had to, on a nickel plated land for a huge lug. This was screwed on and we needed a connection that could sustain a constant 100 amps.

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Regards, Joerg

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