Talk:Printed circuit board

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Opaque ink pens were also used[edit]

Straight onto boards before exposing them, I laid out my first that way. did my 2nd with 1:1 tape onto a board (1 sided, early-mid '70s). And for photo-lithography, I'll bet freehand drawing was used as well, the Flipchip in the 2nd photo looks like it might have been hand drawn, not done with tape. Note the short thick section in the bottom trace, inconsistent with tape, but not with pen and ink, and in general doing curves like that with tape would have been a real pain. Hga (talk) 19:17, 8 November 2015 (UTC)

I've still got such a pen. Don't think that it's a viable technique any more though, electronics has got too small for that. I don't think you are right about the board being done freehand. The roundels are too round and the trace widths are too consistent. The thick piece you point out looks like a solder blob to me. Curves are actually quite easy with crepe tape, which is what we used to use, especially with thinner traces like on this board. The clincher for me is that the top trace goes off the boundary of the board, a very unlikely mistake for someone drawing directly on to the surface. SpinningSpark 20:28, 8 November 2015 (UTC)

Good but rationalization would be an improvement[edit]

It is obvious that a lot of work has gone into this article and there is a load of good information, but suggest that some rationalization of the the content/heads would make it more readable. A bit of copy editing here and there would help too. CPES (talk) 10:49, 9 June 2016 (UTC)

You're doing a good job, but it is my non-expert and possibly incorrect recollection that when using IR reflow on surface mount PCBs, that glue is not always necessary; the solder paste has sufficient adhesion for small parts. Not so? Constant314 (talk) 12:01, 9 June 2016 (UTC)

Decreasing trace impedance is not correct[edit]

Currently the articles states that "The impedance of transmission lines decreases with frequency", even though earlier it is stated that the dielectric constant (Dk) is "usually decreasing with frequency". Actually, if Dk decreases with frequency, that means the characteristic impedance will increase. Lower Dk means lower per-unit-length capacitance, which means higher sqrt(L/C).

The article should state that trace impedance will increase for typical materials which have Dk decreasing with frequency. — Preceding unsigned comment added by Mbleslie (talkcontribs) 17:49, 28 November 2016 (UTC)