Post by thread:[OT] : How does my first PCB look?

> Dual-layer PCBs are overrated, anyway -- unless you can get the > second layer free. :) The last two times I got stock, one was from a Dick Smith sell-out (ah, words that go together) and they were throwing out dirt cheap what they had left, A5 double-sided. Presumably nobody wanted it as much as single-sided. The other was from the scraps bin, very useable scraps actually, of a board house. I was told the only single- sided they use is phenolic, and not all that often. Otherwise all their stock is GRP double-sided. So all my home-made second layers will be free for the foreseeable future. Not that I don't use single-sided when possible, it's wasteful to etch a whole unused layer off

Jinx wrote: >> Dual-layer PCBs are overrated, anyway -- unless you can get the >> second layer free. :) > > The last two times I got stock, one was from a Dick Smith sell-out > (ah, words that go together) and they were throwing out dirt cheap > what they had left, A5 double-sided. Presumably nobody wanted it > as much as single-sided. The other was from the scraps bin, very > useable scraps actually, of a board house. I was told the only single- > sided they use is phenolic, and not all that often. Otherwise all their > stock is GRP double-sided. So all my home-made second layers will > be free for the foreseeable future. Not that I don't use single-sided > when possible, it's wasteful to etch a whole unused layer off I meant if you get the board from a board house. I think doing dual layer PCBs by hand is too much hassle, better to have a few jumper wires. IMO, it only makes sense when you have to have parts on both sides. Vitaliy

> I meant if you get the board from a board house Ah, yes. Just from local experience, the board house start with double- sided stock anyway so the customer can choose to use it, or not > I think doing dual layer PCBs by hand is too much hassle, better to > have a few jumper wires. IMO, it only makes sense when you have > to have parts on both sides Would generally agree. Some double-sided home-mades can be quite tricky. Not impossible but there's an extra level of care needed. For example large DIPs with paralleled pins, like memories, are easier to route with tracks on both sides Don't want to re-hash the recent discussion, but personally I'll have a go at any board at home if there's a reasonable chance of success. In the last few years the only board that didn't work out after several tries was an adapter for an SMT 60-pin micro connector. The board itself wasn't the real problem, although laying out 0.5mm traces by hand was hard enough.. It was that the connector was made of heat-sensitive plastic that deformed badly when soldered, even with great care. I gave up eventually and added the footprint to a board that was being pick-and- placed. The assemblers did a good job. Lesson learned

On Wed, 18 Feb 2009 20:36:57 +1200, "Jinx" <spam_OUTjoecolquittTakeThisOuTclear.net.nz> said: > stock is GRP double-sided. So all my home-made second layers will > be free for the foreseeable future. Not that I don't use single-sided > when possible, it's wasteful to etch a whole unused layer off Many times what I do is use the second layer as a ground plane. Tape the ground plane side, etch the real side, peel off the tape, drill the holes. Then remove the copper on the ground plane side at non-ground holes using a special flat drill bit with pilot. I've seen those drill bits commercially but I have always made them from broken drill bits. Chuck it in a drill press, spin it up, make the pilot with a dremel tool and cutoff wheel. Then by hand, add a bit of cutting angle with the cutoff wheel. Cheerful regards, Bob -- http://www.fastmail.fm - Same, same, but different...

Bob Blick wrote: >> stock is GRP double-sided. So all my home-made second layers will >> be free for the foreseeable future. Not that I don't use single-sided >> when possible, it's wasteful to etch a whole unused layer off > > Many times what I do is use the second layer as a ground plane. > > Tape the ground plane side, etch the real side, peel off the tape, drill > the holes. > > Then remove the copper on the ground plane side at non-ground holes > using a special flat drill bit with pilot. > > I've seen those drill bits commercially but I have always made them from > broken drill bits. Chuck it in a drill press, spin it up, make the pilot > with a dremel tool and cutoff wheel. Then by hand, add a bit of cutting > angle with the cutoff wheel. Fascinating. Can you explain the last sentence? Vitaliy

> Chuck it in a drill press, spin it up, make the pilot with a dremel tool > and cutoff wheel. Then by hand, add a bit of cutting angle with the > cutoff wheel. > > Fascinating. Can you explain the last sentence? Sounds like a pointy spot-weld bit http://www.autobodysupplies.com/titanium-spot-weld-bit.gif or a milling bit with a point

part 1 640 bytes content-type:text/plain; charset="ISO-8859-1" (decoded 7bit) On Mon, 23 Feb 2009 02:25:56 -0700, "Vitaliy" <.....spamKILLspam@spam@maksimov.org> said: > Bob Blick wrote: > > I've seen those drill bits commercially but I have always made them from > > broken drill bits. Chuck it in a drill press, spin it up, make the pilot > > with a dremel tool and cutoff wheel. Then by hand, add a bit of cutting > > angle with the cutoff wheel. > > Fascinating. Can you explain the last sentence? They say a picture is worth a thousand words, see attached. Cheers, Bob -- http://www.fastmail.fm - A no graphics, no pop-ups email service part 2 16971 bytes content-type:image/jpeg; name="special_drill_bit.jpg" (decode) part 3 35 bytes content-type:text/plain; charset="us-ascii" (decoded 7bit)

Bob Blick wrote: >> > I've seen those drill bits commercially but I have always made them >> > from >> > broken drill bits. Chuck it in a drill press, spin it up, make the >> > pilot >> > with a dremel tool and cutoff wheel. Then by hand, add a bit of cutting >> > angle with the cutoff wheel. >> >> Fascinating. Can you explain the last sentence? > > They say a picture is worth a thousand words, see attached. Indeed. Thanks! Vitaliy