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PCBs vs. perfboard

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Dr. Shark

Mon Feb 13 2006, 10:03AM

Registered Member #75 Joined: Thu Feb 09 2006, 09:30AM
Location: Montana, USA
Posts: 711

I have never made any PCBs, but now that I start playing with SSTCs including "complicated chips" like PLLs and all the added difficulty of high frequency / low inductance layouts I am wondering if it would be a good time to get into it. Is this a good idea, or is it possible to get these circuits to work on stripboard?

If I decide to go the PCB route, what kind of equipment would I need? Photosensitive boards, ferric chloride, (I have a UV light source and a laser printer), thats it, or are there better ways to do it? This would not even be a big investment, but still I am wondering if the additional effort of making the PCBs will pay off, or if I can stick with stripboard.

EDY19

Mon Feb 13 2006, 11:33AM

Registered Member #105 Joined: Thu Feb 09 2006, 08:54PM
Location:
Posts: 408

PCBs make things much easier. For your first couple of boards, stick with single sided though, I have always had trouble aligning double sided ones. Just use jumper wires instead of bothering with etching a whole other side. Also, laser printing on photo paper or magazine paper works great, just make sure you iron it for long enough.

Dr. Shark

Mon Feb 13 2006, 11:42AM

Registered Member #75 Joined: Thu Feb 09 2006, 09:30AM
Location: Montana, USA
Posts: 711

Is this the method were you iron the toner from the paper to the PCB? I guess this makes it easier as you dont have to bother with exposing and developing. I think that board without the photoresist are also cheaper.
I have never done ironing thoug, I don't even have an iron :P

HV Enthusiast

Mon Feb 13 2006, 12:43PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

For PCB work, check out

They have their own free downloadable software and boards cost as little as around $50.00 for (3) identical boards which are like 3 x 4 inches or something like that.

Maz

Tue Feb 14 2006, 03:01AM

Registered Member #111 Joined: Fri Feb 10 2006, 01:04AM
Location: Menasha,Wisconsin
Posts: 65

thats a little expensive when the boards for that size cost a couple bucks. you can always download their software and then print it out and make your own. ferric chloride, photopaper (more gloss the better), and settings set on max dark, you should be good to go. heck, i figured it out.

Hazmatt_(The Underdog)

Tue Feb 14 2006, 07:32AM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

I've done a lot of boards over the 8 years now I guess it is, boy the time flies.

I've tried to sensitize my own, which didn't turn out so good. The sensitizer is really runny.

I've done some double sided, which, if done in a clever way, can turn out well. You need a lot of alignment targets on the transparency for mask alignment, and some lines for board alignment.

I've done photo with flourscent, which turns out pretty well if you remember a few rules.
1 tube very close is okay, 2 tubes you need a diffusor, I had 3 tubes without diffusor and had poor exposure!

I've left boards out in sunlight for 10 min. and they come out fine as long as you don't use too concintrate fixer, DOH!

I've masked by hand, and do this very often, I'ts much quicker.

I've used Permanant Marker....BIG BIG MISTAKE. Rubs off way too easy during agitation in tank. USE PAINT PENS! Also, a paint pen saves a lont on donuts!! Just use the big fat one and dab it were you want the donut! IT works!

I used to do small batches, A 5 gal bucket 3 gal full is much better, no dumping! and less cleanup!
I've also etched in cold weather, which is difficult. Get a 200W fishtank heater, its worth it!

If you want to do boards frequently get a 2 axis table for a drill press, sand the travel planes for smooth gliding and work it in, takes a couple of years, but once done, it works good!
Cheapo table like mine cost $200, Harbor freight equavilent avaiable through Grainger.

Carbide drills snap a lot, get #65 and #70 High Speed Steel drills, these are common hole sizes, are more forgiving, and don't cost $3 each.

Complex boards can be made by laying out your board, fixing graph paper to them, laying out your planned drillholes, drilling, then masking and etching. I use this process a lot. It takes several hours but is sometimes faster then other methods.
I have done 300 hole+ boards this way.

clean your boards before use with HCl. This works well. Also #0000 Steel Wool is a must. Shine up the board before use/layout. It improves etch time, which reduces risk of over-etch

Double-glove! Cheapo latex gloves get eaten through pretty often.

You can swab the board gently during agitation to increase etch rate IF you're very careful! Do not swab the traces, they will come off. But you can swab over traces layed down by Paint Pens. The paint is very durable even in this enviornment.

DATAK has expensive products. RadioShack has etch-packs of 4 sheets for $1.19. They also come in handy for pannel artwork! Buy them out!

I could go on...but I know this is getting rediculous. I'm sorry! There is a lot to boards.

ragnar

Tue Feb 14 2006, 01:19PM

Registered Member #63 Joined: Thu Feb 09 2006, 06:18AM
Location:
Posts: 1425

I first started pretty much with the hvguy.com method (the page is down now).

I slightly adapted their method to suit my circumstances (only had ammonium persulphate, no ferric chloride, etc)

Rather than regurgitate their method of the top of my head, here's what worked best for me:

==============================

Stuff you need:

==============================

Dry kit:
A kettle,
JIF/comet abrasive cleaner,
Flux paste (mine was zinc chloride or something),
Copper clad board,
Thin permanant marker,
Methylated spirits,
Ammonium persulphate.
600-grit sandpaper,
Tissues.
A scrap of closed-cell foam sheet (a strip from a polystyrene foam cup will do)
A big sheet of cardboard to work on.

Wet kit:
Tub of rinsing water for your eyes/hands in emergency,
Box/tray in which you'll etch your board,
IC tube to stir the etchant with,
A cable tie, or some insulated wire to hold the board by,
A lint-free, smoothish cloth which will be used with methylated spirits, abrasive cleaner and to wipe grit off etc.

==============================

The process:

==============================

1) Cut board to size,
2) Drill hole in corner of board,
3) Clean the copper with methylated spirits and a tissue,
4) Sand the copper (only back and forth, not circles) with 600-grit sandpaper. Wipe with the cloth.
5) Use JIF/comet cleaner on the corner of a cloth, back and forth... don't forget the edges of the board. Wipe.
6) Sand the copper again with 600-grit paper. Wipe off with a cloth.
7) Clean the copper again with methylated spirits and a tissue.
8) Dunk the board in water, remove. If it's nice and clean, you'll get a giant meniscus over the whole board; it'll hold water. If it runs off, it needs more work.
9) Wipe the board, and clean him with methylated spirits again to make sure he dries.
10) Draw on your artwork thickly with a name-brand, fine permanant marker. Wait for it to 'dry'.
11) Draw the artwork again over the top; check it's completely black, no copper showing through.
12) Now, with a sharp, precision craft knife, scrape off any marker where two tracks threaten to be close to each other. Pick off any lint or hair stuck in the marker.
13) Boil the kettle. Put the right amount of ammonium persulphate into a plastic tray/box not much bigger than your board. Put some thin, insulated wire through the hole in your board.
14) Check which way the wind is blowing. Lean back, wear goggles. Pour boiling water into the tray. It may fizz/spit a little. It doesn't hurt to have preheated the tray before you put your ammonium persulphate in. Stir it to dissolve with something inert, like an IC tube :P
15) Drop the board in so that it sits flat on the bottom of the box with copper facing up. Swill him around. It shouldn't take more than a few minutes for the copper to fade away at the edges and gradually disappear.
16) Remove your etched board, and rinse him quickly in your rinse bucket. Wipe both surfaces (underwater) with your fingers or a cloth to remove any residues.
17) With a tissue, clean the copper with methylated spirits to remove the permanant marker ink.
18) Wipe one side of one end of your foam in the tin of flux. Now with your finger on the dry side of the flux end, wipe it all over the board. It'll be grippy at first, but when it glides smoothly (with pressure) all over the board, the flux should be nice and thin, smooth. You'll get a feeling for it... it'll feel like rubbing the foam around on something slick and greasy.
19) Tin the board with an iron. Try to keep any soldering/flux vapours out of your eyes and mouth; the flux has some tang to it, you'll know if some drifted in there. :P The solder should flow *really* easily onto the board if you've used the flux well. You should be able to put just a touch on the tip of the soldering iron and it'll flow on. Retin the iron when necessary. For big boards like fullbridges, you'll probably need an 80W iron to allow you to tin quickly and effectively without the tracks lifting off.
20) With the corner of a tissue dunked in methylated spirits, wipe any remaining flux off the board. Repeat.
21) Populate with components, surface-mount style =-)

Done!

I guess you can substitute ACETONE for Methylated Spirits ("denatured alcohol, to you guys?"). Acetone flashes off faster and tends to attack residues on the copper better.

After writing down this method which guarantees I don't stuff up, I found it VERY rewarding. It really revolutionised the projects I was able to tackle. It makes protoboard feel impractical and ugly. I no longer spent hours debugging my horrendous vias and board-jumping bad wiring, I know exactly where stuff is going, and I can be proud of having my own hand-made PCB.

I might mention, after about the tenth time, I had the production time down to 40 mins for a board of just about any size, discounting designing the artwork. Because I don't have a sacrificial microwave or an etching tank, I just used a miniscule amount of etchant and discarded it after use.

After that, I moved briefly onto CNC engraved boards, which was a nice adventure, now immortalized in the forum archives somewhere... there were some nice pics to ogle at, but I didn't get all that much feedback about the boards themselves.

Now I do toner-transfer by the Gootee (googlable, if it hasn't been mentioned already) method. I'm still getting used to it, but it's faster and cheaper than engraving... just confusing reversing the artwork and all, ;)

Part Scavenger

Tue Feb 14 2006, 06:39PM

Registered Member #79 Joined: Thu Feb 09 2006, 11:35AM
Location: Arkansas
Posts: 673

I use the goatee process. I'm NEVER going back to perfboard unless it's a small circuit. It's not really hard to line up the sides if you use plenty of "crosshairs" and maybe predrill a hole. My only problem that I have with this is that one side peels off razor sharp, and the other all muddy but usually still usable. I can't figure out how to make this better, but I haven't had too much time to experiment or re-read the tutorial(maybe he has an answer there?)

Those drills(I use carbide) are pretty robust at high speed(dremel press). I haven't killed one yet, and I've been pretty mean to it on accident a few times. Once, it even got caught sideways! I even *gingerly* mill with it sometimes.

To go the PCB route you'll need echant, boards, etc.

The echant is cheapest at my Radio Shack, (don't know about your's it really suprised me it was cheap there)
PCBs are cheapest at Goldmine Electronics. DEFINITELY by their suprise copper clad pack. Well worth it!!!
I use kodak photo paper for the iron-on. Just what I had, so I tried it. He uses cheapo staples paper.
Laser printer or copier... This is where most of us get stopped.
Iron
Acetone is abosutely a nessisity. It will melt the toner right off. Don't bother with scrubbing, it ain't worth it.
Bubble tank? I don't have one, but I'd be really nice not to have to shake a dish for 10 min.
Old microwave. Not a necessity, but I like to get the echant really hot first. You'll wind up eating out the guts with the fumes; that's why you use an old one.

Drill and bits. Get a high speed drill and a drill press with the least amount of give left to right you can find. I use one my dad made me(see Scavenger's DRSSTC on the old forum) and it's perfect. It's small, so you can have that "feel" I guess you could use a dremel strapped to a big drill press, but you're likely to crush you bit or something. Carbide #66-67 bits are really hard to find at all. I bought a box at goldmine for $40 (50 bits, haven't broken one). If you can find them, they are usually 2-4 dollars apiece. GET CARBIDE if you can get ahold of a high speed drill. They'll almost never go dull. If you use a regular drill press, get the standard/HSS ones, they will dull more quickly but will not snap as easily. If you have to buy a dremel, be careful about *give*.

I wouldn't suggest going the UV/develop table with photoboards, it looks too expensive if you screw up. However, it has pretty clean results.

One thing I would add to the goatee process: add a piece of plain paper inbetween the photo paper and the iron. Goatee doesn't but it messes all up on my kodak paper.

EDIT, Oh yeah, make sure you mirror the TOP of the board. If you don't mirror one side, they won't line up. If you don't mirror the TOP everything will still connect properly, BUT the IC pins will be reversed. So any IC's on the board won't work.

ragnar

Tue Feb 14 2006, 08:17PM

Registered Member #63 Joined: Thu Feb 09 2006, 06:18AM
Location:
Posts: 1425

Part Scavenger wrote ...

EDIT, Oh yeah, make sure you mirror the TOP of the board. If you don't mirror one side, they won't line up. If you don't mirror the TOP everything will still connect properly, BUT the IC pins will be reversed. So any IC's on the board won't work.

Ahhh, tsk tsk tsk. You do not know all the tricks of the trade, grasshopper.

If you should make such an error, and a sense of urgency requires that you use the board you just made, you may carefully fold all the pins of the chip out and UP so when you plug him in, you see the BOTTOM of the chip, and the text is facing the socket/board... muahahaha

In fact, this is how I build my UCC drivers these days back to back... It's very sneaky, and allows me to minimise the size of my boards without having to build crosslinks etc etc etc, cause I can put my UCC chips right next to each other, with the inputs down the centre, and the outputs on the outside.

EEYORE

Tue Feb 14 2006, 08:30PM

Registered Member #99 Joined: Thu Feb 09 2006, 06:10PM
Location: florida, usa
Posts: 637

EastVoltResearch wrote ...

For PCB work, check out

They have their own free downloadable software and boards cost as little as around $50.00 for (3) identical boards which are like 3 x 4 inches or something like that.

Ahh yes, my favorite method...No way you can make your boards as nice at home...Just nice and precise!Pretty too...
Matt

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