MANUFACTURE PCB

[Pete the Builder]

Hello Pete,

For my boards I use most 0,8 mm for tracks and 2,0mm for pads as best, (dips 1,6mm) no go between dip's ...beter an extra link on the board.. and lots off space for tracks and pads..

Most DIY people here have 'normal' tools .. so design boards that can be made and used by all ... just may way..

Best regards.

Ap

That's right up my alley. I veer away from huge square pads with enormous blank voids, as that makes it so much harder to drill accurately, and pointy things always mess things up in a complicated layout.

I use very conservative tracks and pads everywhere (typically 25mil for signals, 70mil for low-current power, 200mil for high-current) (Sorry, I learned all my drafting in the late 70s, and it's the one area I still can't metric-ise... I'm starting to have to for MCUs, they're nearly always in mm these days).

I drill all my single-sided stuff by hand too, so I know how important that is. You'll find that I use big round thick pads for passives, generally 60mil with 32mil holes, so after plating there's still a generous solder area and the leads don't get stuck or damage the plating. I'm really fussy about IC pads, power tracks, signal traces, and capacitive and inductive coupling, but that's from a TTL or CMOS digital perspective. It will be interesting to work with microvolts and picofarads making a difference!

And I always go overboard on mounting holes wherever I can get away with it. There's nothing worse than having to dig around for an insulating washer because some ******** has put components too close to the mounting hole. Or worse, the holes are too small and there's not enough annulus! I always create mounting holes to take M3 or M4 screws.

As far as grounding goes, I'm quite happy to do a VCC/GND plane fill for those who like that, or a GND/GND for the traditionalists, or a single GND plane, or none at all. Altium makes that stuff so simple it's ridiculous. As long as I remember which is which, of course!

I might put up a recent PCB design to show what I mean. I think I still have an old Rover design floating around on the big system. I'll dig it out and post it here so folks can see what I mean. That's probably better than just flapping my gums about how wonderful, intelligent, and handsome I am.

-Pete

[Pete the Builder]

I prefer jumpers over 2 sided PCBs and no tracks between IC pads.
I'm OK with 2 sided boards, provided one side is exclusively used for ground plane and preferably with heat relief pads for ground connection. And certainly no vias.

...and would you like fries with that?

Don't forget, I can arrange for manufactured double-sided boards, with solder mask and so on, which makes the final design a lot more robust - not to mention easier to solder! I get them done through ETT in Thailand, and so far they've been exceptionally well-made. They'll even go outside spec if you ask nicely, and they're always happy to cut the boards as well. And even with a $25 solder mask and $25 silkscreen setup cost, single board quantities are really reasonably priced. And if a design is popular, that works out to be an extra couple of bucks a board. And the solder masking sure makes it easier to do a great job, and it beats the heck out of trying to align vias by hand!

If you have specific requirements above and beyond typical relief specs, I'm more than happy to add prunes to All Bran. I'd rather over-design something and have it last a lot longer and keep you a happy camper, than take shortcuts and risk reliability. It's just the way I roll...

Thanks for the feedback!

[Davor]

I prefer jumpers over 2 sided PCBs and no tracks between IC pads.
I'm OK with 2 sided boards, provided one side is exclusively used for ground plane and preferably with heat relief pads for ground connection. And certainly no vias.

[ApBerg]

What's the highest resolution you can get with screen printing? Can you get tracks between DIP package pads, for example?

The reason I ask, is that if everyone knows what the lowest common denominator people are using, the design guys (including me hopefully!) can take that into consideration when designing boards for folks.

I use the Press-N-Peel exclusively, simply because it's so darn easy - print, iron, etch, and it allows use of extremely fine-pitch packages. But I don't know what the limits of screen printing - the type of printing that people have access to, not "perfect" professional limits - are. Any ideas?

The reason I ask, is that if everyone knows what the lowest common denominator people are using, the design guys (including me hopefully!) can take that into consideration when designing boards for folks.




Hello Pete,

For my boards I use most 0,8 mm for tracks and 2,0mm for pads as best, (dips 1,6mm) no go between dip's ...beter an extra link on the board.. and lots off space for tracks and pads..

Most DIY people here have 'normal' tools .. so design boards that can be made and used by all ... just may way..

Best regards.

Ap

[Pete the Builder]

What's the highest resolution you can get with screen printing? Can you get tracks between DIP package pads, for example?

The reason I ask, is that if everyone knows what the lowest common denominator people are using, the design guys (including me hopefully!) can take that into consideration when designing boards for folks.

I use the Press-N-Peel exclusively, simply because it's so darn easy - print, iron, etch, and it allows use of extremely fine-pitch packages. But I don't know what the limits of screen printing - the type of printing that people have access to, not "perfect" professional limits - are. Any ideas?

[schpeedy]

For very fine traces a constant circulation tank is required, or a manual rinse, as most etching processes are self accelerating to a point.

Hydrogen peroxide and hydrochloric acid mix is another rapid etching solution (giving results in tens of seconds compared to tens of minutes) if some prescription etching agents are not available. I've used 3 parts water, 1 part 30% H2O2 and HCL each.

ive also etched my pcb with H2O2 and HCL. And i can also confirm the rapid and precise result.

greets.

[ApBerg]

Hi Ap

Here's a link to small scale bench top screen printing for pcbs. This method also
makes nice control panels, printing directly on the box or face plate.

http://www.cbridge.com/howtos/printedcircuitboard.shtml

Nice again.. always wanted to know an easy way for as they call it 'screen printing' (zeefdruk in Dutch ?)
Will study it !

Thanks, ..also for the other friends for the info, all know more than one..

Ap

[satdaveuk]

Best results

The best results ive personaly had turned out the cheapest way.
Which is get hold of factory data paper, it comes in very large rolls with holes either side which I presume is what draws the paper through the machines, its wider than A4 so you can cut to size
I dont know why it works so well, its not glosst but not mat, its easy to get off under the cold water tap after heat treatment, which means your not taking print off with it.

Now you may or may not laugh but this is the secret: Print with laser like we do on best quality, very very important make sure your copper clad is spotless, I use fine emery cloth followed by industrial alchol, followed by hot soapy water, followed by very hot plain water under the tap and dry with kitchen towl.
Make sure you dont touch the copper clad surface with your fingers otherwise you will need to do it all over again theres no short cuts.

Next print your PCB layout (mirror side down) and cut leaving enough to wrap edges around reverse side of PCB, then drawing ontop of copper clad surface , wrapping edges tightly round reverse side and tape with masking tape or similar whilst checking you have complete drawing on copper side.
I found using a house hold iron is to violent and to much heat can damage and cause lifting of the copper off the board, so to overcome this put it in a postal envolpe and repeatedly run it through a bog standard laminator at least 25 maybe 30 times alternating entry directions.
After that while still hot just put it stright into your freezer for 15-20mins.
When you get it out of the freezer it will have a light frost over it, just put it in the kitchen sink with cold water and rub off paper with thumbs, it comes off so easy.
Try it and you will be pleased with results.
Dont be tempted to miss out the freezer because thats what hardens the resin and why it sticks so well the the copper clad.

The laminator idea I got off the net, the data paper and freezer idea was all mine by trial and error.
Regards

[Pete the Builder]

Please post the link.

Wow, they're still in business! I checked my email archives, the last time I bought from them was in 2005! And I still have a dozen sheets left!

Anyway, the URL is http://techniks.com (if I'd remembered the damn URL was so simple, I would've posted it... sorry about that!)

Their HSS drill bits are better than any others I've found at anywhere near the price. I can typically get 200+ holes out of single 35 mil bit, in 1/2 oz FR4, (which is what I use for my protos).

They were extremely reliable, and packed everything properly - no folded sheets, and usually there were an extra couple of sheets in their 50 pack (but I wouldn't expect nor demand it from them if you only get 50!), and quick too. I spent quite a few hundred bucks with them over a period of 5-6 years, with nothing "lost" or delayed by customs. YMMV.

I hope this helps!
-PtB

[6666]

I'll post the URL

Please post the link.

[Altra]

Hi Ap

Here's a link to small scale bench top screen printing for pcbs. This method also
makes nice control panels, printing directly on the box or face plate.

http://www.cbridge.com/howtos/printedcircuitboard.shtml

[ApBerg]

Probably the first method of producing pcb's was screen printing. I used it many years ago with
much success. It's really good for small production runs. I had a friend who printed t-shirts
for a living, create a screen for me. Nobody ever mentioned this method here. Good to know, not
practical for one or two.

Here's a video of a guy making audio power amps in Colombia
http://www.youtube.com/watch?v=8-WGaAmpfOU

Nice link !

[Altra]

Probably the first method of producing pcb's was screen printing. I used it many years ago with
much success. It's really good for small production runs. I had a friend who printed t-shirts
for a living, create a screen for me. Nobody ever mentioned this method here. Good to know, not
practical for one or two.

Here's a video of a guy making audio power amps in Colombia

http://www.youtube.com/watch?v=8-WGaAmpfOU

[ODM]

For very fine traces a constant circulation tank is required, or a manual rinse, as most etching processes are self accelerating to a point.

Hydrogen peroxide and hydrochloric acid mix is another rapid etching solution (giving results in tens of seconds compared to tens of minutes) if some prescription etching agents are not available. I've used 3 parts water, 1 part 30% H2O2 and HCL each. The solution can also be relatively easily recycled with a bit of attention, for regular pcb making, as the end product is cupric chloride. The bare peroxide/hcl etchant quite rapid and requires manual agitation for good results (stir board in solution and detach bubbles) while the cupric chloride etchant is closer to fresh ferrichloride, and recyclable with air bubbling and adding hcl.

I rarely do my own pcb protos these days though - dead bug construction gives good results for impulsive high frequency prototyping, and for more complex (or messy!) things, the price of decent factory made boards have gone down in the last decade.

[Pete the Builder]

G'day guys,

I know this is a pretty old thread, but I hope I can add a little something...

Throw away your ferric chloride!! Try some ammonium persulphate instead. It's cheaper, it's much nicer to use (no brown yucky stains all over hands, clothes, bench, pets, children, etc ), and it etches about 3-4 times faster than Fe2CL3. If you warm it, it can quite literally etch a 6" x 8" 1/2oz FR4 board in less than two minutes. I've done that with Press 'N' Peel once, in a "bubbler" tank. You can buy the ammonium persulphate at Jaycar in Australia, and most good pharmacies will have stocks of it. Try the older pharmacies, not the new chains. Most chemical companies will sell it to you, and it's sometimes used as hair bleach.

Regarding Press and Peel film : FWIW, I design a lot of very fine detail digital boards (down to 6 thou (0.16mm) clearance, with 8 thou (0.2mm) tracks - think SOIC, TQFN, and QFP-144!) and the blue Press 'N' Peel is far and away the best for the job. Of course, the copper must be exquisitely clean!

And for those with only inkjet printers, may I suggest looking at the big electronic stores near you (if you have easy access, of course!), or on eBay if that is an option, for cheap laser printers.

I used inkjets exclusively, but I really wanted to try the PressNPeel film... Then a local electronics store got a stock of cheap Chinese "no brand" laserjet printers - for just AUD$88.00 each!! (It cost me less for the printer than it would cost for a replacement toner (AUD$165.00)!!) I've used that printer just for toner transfer for PCBs, and after 4 years, I still have not run out of toner from the original cartridge. Of course, I wait to print multiple designs on one sheet, to minimise wastage and PnP sheets.

And you can buy 25 PnP sheets in bulk for less than you pay for a pack of 5 sheets from electronics stores. I'll post the URL if anyone is interested. They also sell packs of PCB drills, dedicated ironing machines, all sorts of stuff. (I don't have easy access to my main system where all my PCB stuff is located right now, but if anyone is interested, I'll be happy to get the details!)

It doesn't make sense for me to even try double sided PCBs. They're too fiddly, and I can get them made by ETT in Thailand cheaper and for less hassle - and they do silk screening, masking, everything. But I still prefer to make my own single sided PCB!

So I hope some of these suggestions might be helpful for some of you who want to make your own single-sided PCBs.

Cheers,
PtB