Double sided copper boards

[Screech]

Do we use the double sided copper boads to etch links on the other side?
Do we also use the double sided boards to make the circuits smalled in size?

Is that what the other copper side is for?

 

[spyghost]

Do we use the double sided copper boads to etch links on the other side?

do you mean the reference designation of the components? if that is what you refer, i've done it before, but for tightly packed components, its not recommended because it may be a cause of shorts.

Do we also use the double sided boards to make the circuits smalled in size?
Is that what the other copper side is for?

do you refer to the board size? based from experience, double sided boards sometimes don't really reduce board size. it still depends on the circuit you are trying to make. but most of the time, double sided boards reduce board size specifically for complex circuits.

as much as possible, i would like to limit my boards to single sided, but if the application/circuit really requires me do a double sided board, then i'll go for it.

 

[kentken]

I use a double sided board to run the signal traces for display controller chips on the other side.

kent

 

[Klaus]

The minimum size of a PCB is really governed by the area occupied by all the components on it plus a percentage for the tracks & connectors.
You can accomodate a far more complex circuit on a similar size board by having the tracks on both sides.
There are pitfalls with that, for the home PCB etcher, as it is not practical to fabricate plated through holes at home. So, links or component legs have to be used to connect tracks from one side to the other. Problem is that some components ( like IC sockets) can only be soldered from one side.
So, one has to plan the track layout very carefully to avoid too many link through pins.

Some (double sided) boards use straight tracks running all roughly in the same direction on one side and similar tracks at 90 degrees on the other.

Some boards use one side for the power tracks and the other for the signal tracks.

Some boards (RF circuits) use the component side as a ground plane with a clear circle etched at every component leg and link position.

For my projects, I have always given the etching process to a professional outfit - its too tricky to get precise registration of the individual artworks when transferrring the pattern onto the copper.
Klaus

 

[Dean Huster]

Klaus has a great reply.

I might add that there are very few instances where a double-sided board has saved much space in my designs. Getting the registration correct between front and back sides is always difficult, even thought I've developed routines to make that easier. I'm a jumper person, myself. If you have a wire bending jig, it's easy to just make bunches of jumpers and use them when building the circuit. When laying out a board, I try to keep hole spacings standardized if possible, e.g., 0.4" spacing for 1/4-watt resistors, etc. Jumpers are the same. I try to keep them at 0.4" (I have millions of 1/4-watt-sized jumpers on a reel that I use) unless the design absolutely needs to jump longer across the board. That way, I can make up lots and lots of jumpers in one sitting so that less time is spent in custom bends when assembling the board.

Regarding the problem with having to use components leads to make the connections between front and back sides: that's why I distain the use of IC sockets. Besides adding expense and intermittent problems to a project, an IC installed directly onto the board allows soldering on both sides if needed. Few ICs these days require sockets. If you do have a socket that needs a double-side connection, you can usually spot a via 0.1" or 0.2" alongside the pin to make that connection. I don't even use IC sockets on single-sided boards.

Vias? If I need one connection from one side to the other, I use brass straight pins rather than hookup wire. If there are a lot of these vias, I install them FIRST by dropping the pins in the holes where needed, covering the heads with a piece of cardboard and flipping the board over onto a masonite surface and sliding the cardboard out. I then solder the pointy ends of the pins on the "solder side", then flip the board over and solder the heads. Then I clip the pointy ends off. Be sure to use brass and not stainless steel pins! Check your pins for solderability first.

Dean

 

[pike]

I have been attempting to make my own double-sided for a few weeks now.

The way I do it is first iron on the transfer for only one of the sides, then i drill some of the holes for the component layout using the resist as a guide. This then allows me to align the iron-on transfer on the other side.

After this, i then heavily coat the drilled alignment holes with a permanent marker so there is minimal undercutting. sharpie works best.

 

[Oznog]

As far as shorts go, it will not happen it you pay attention to the case type of the components in question. For example, don't run wires under a metal-cased crystal. You might do it if you had a soldermask, but not if you're doing it at home.

You can get a lot better density with double sided. Creating a lot of jumpers is like doing a lot of point-to-point wire soldering. Depending on the board, you may not be able to avoid a lot of jumpers even if you make the board overly large.

The only problem is DS requires thruholes. In commercial mfg, copper is embedded in the holes to connect top & bottom traces, but you can't do this at home so you get stuck trying to do it with wire & leads.

I would only use SS for pretty small designs. If it's bigger, I'll send it out to prototype PCB mfg guys like Olimex who can do DS.

 

[Dean Huster]

My gosh! How can you guys afford to send onesey-twosey designs out for custom PCB manufacturing? Half the object of hobby electronics is home-brew. Good grief! In the same vein, I never did understand any hobbyist who would want to order a factory-assembled Heathkit. What's the point?

It's a shame that the hobby has gotten to the point where you need to spend $800 on a computer, $500 on a laser printer, $300-$1000 on various software packages (skem capture, autorouters, sim, assemblers, etc.), $200 on each oddball programmer you need and then farm out the results to a PCB farm.

Ham radio has gone the same route. A hobby that used to be a large percentage of home brew (with the usual but not always exception of the receiver) is now almost 100% off-the-shelf, turn-key purchases. The technology has swamped the technicians. What a shame!

Dean

 

[Klaus]

Dean, don't be too dismayed. There's still plenty of home brewing going on if one reads this forum. However, one has to face reality too, after all, we don't drive model A Fords any more either :wink:
With regard to PCB making at home, fine for simple single sided boards and it gives one a good insight in the etching process.
However, it also leaves one with a batch of nasty chemicals to get rid off eventually. And, the result of a home PCB etching process, especially about where the tiny spots to drill the holes later is concerned, often leaves a lot to be desired.

You'll find that almost all professional PCB makers have a prototype special on offer. So, for just a single board, the price is very reasonable if one supplies one's own artwork ( check first what software they use).
That way one gets a real flash PCB which can often be had even cheaper if one requests no holes drilled, assuming one has a suitable drill press and carbide drill bit for that job.

With regard to your amateur radio comments, yes, a ready to use transceiver seems to be the norm these days but there is still room for home brewing other bits like low pass filters, antenna checking gadgets, various power supplies, even solid state linear amplifiers and, of course, the antenna itself. I have a box full of home brewed amateur gadgets that, sadly, have not been used for a while since I am not active these days.

Klaus, VK6AKS

 

[Dean Huster]

Jack Benny was still driving his infamous Maxwell in the 1960's. I guess I'm the same way.

Klaus, I guess I consider myself to be a "frugal hobbyist". It's rare that I have to spend much money on a project. I have thousands of transistors, diodes, TTL ICs and CMOS ICs on hand. I'll design a circuit using those older components before I'd consider a processor-based design. Maybe it's silly, but I've not had to buy into all the software and programmers and still am able to design and build what I need. If I can make a cake from scratch with the stuff in my kitchen cabinet, why should I run to the store for a Pillsbury box cake?

I informed folks up-front of that little quirk of mine when I was writing the "Q & A" column for Poptronics magazine before it folded. I even went so far as to design a TTL horizontal line counter for a video triggering adaptor for an oscilloscope! I'm certain that a PIC could have done the job in far less space, but what fun the TTL version would have been!

Taking a look at all the newer ARRL Radio Amateur Handbooks, I've noticed that the emphasis has been taken away from construction -- a lot. Yes, there are some linear amps, but mostly any construction deals with rinky-dink accessory items as you mentioned. Now the emphasis is on interfacing your PC to your station. Sit back and listen to your MP3 player while your PC makes all your contacts with other PCs. Isn't that like taking a taxi onto the racetrack rather than driving the car yourself?

And with mention of Poptronics magazine, it did fold as mentioned. That left only one general electronics hobbyist magazine in the U.S. At one time during the 1960s, we had 7 or 8 general electronics magazines being published in the U.S. simultaneously and most of them were wonderful magazines! Maybe THIS forum shows some hobby activity going on, but not that much. The lack of interest in the magazines is a strong indicator of what's happening to the hobby. The original Popular Electronics forum was HOT! After a few years, it started cooling off and now there's few general electronics forums that are really active. The EPE forum isn't bad, but I sense a change there, too. The current Poptronix forum is nearly dead; it appears that Charles Wenzel's forum has died; Tony's forum seemed to start OK, but didn't last long. The forum run by Nuts and Volts Magazine is still going fairly well, but again, it doesn't seem to have the life that I've seen in the past.

Vocational and technical schools all over the U.S. are dropping their electronics programs in favor of computer repair and computer networking programs. The electronics those folks know is embarassing.

I love this hobby a lot, but am sure starting to feel like a dinosaur.

Dean

 

[panter]

Missing hobbyists?

apparently I have noticed something similar, but I'd like to give some other perspective here.

I am not a hobbyist, although I like very much what I do. I Own a small workshop for customer support/maintenance of various chemical/physical laboratory stuff. Mainly Spectrophotometers, AASP, GC (MS), LC (MS), etc.
Considering boards I do often get itmade by someone else, but often I also lose my nerve and fiddle with it myself. I still like their result better, It look awesome and generally is a good start for the project.
I think there is somewhere else that we can see the lack of hobbyists on. More and more I do see more sophisticated equipment but with some basic electronic stuff lacking. It might sound crazy, but people (and I'm talking serious angineers in prettyu serious companies) seem to forget small things that they would not if they did some hobby stuff before. I see more weak joints, bad hinges, linear ADC/DAC's i logarythmic circuits trying to overcome resolution problems by just increasing it beyond sense...
On a computer all seams to work fine, and probably emediatelly after production, but later i do get serious problems due to these designers choices.
WE NEED HOBBYISTS!

GUYS, ASK, ANNOY if necessary, Drag do what You think is necessary, but still DO what You DO!

That's all folks.

Milos Pantelic
service/cstomer support
ALFA servis
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