PCB home made suggestions

[akis]

Hi

I am sure this has been discussed before in other threads. I have decided to make home-made PCBs.

I will use the Laser printer method, initially using ordinary paper and if that fails, Maplin sell a "press and peal" transfer system for 19 pounds per 5 sheets (approx 11" x 8.5").

Maplin also sell etching crystals for 9 pounds per 2.5lt. I have estimated a 4" x 4" board would need approx 340 cm3 - so if we renew the fluid on every board then the 2.5lt should be enough for 8 boards (4" x 4").

I will also need to buy a small drill a lots of drill bits and also special jigsaw blades if I have to cut the boards to size.

Maplin sell fibreglass two sided boards for 2.63 per 10 boards (10" by 6")

Is there an alternative method, a cheaper place or something else I am missing?

Thanks

[dchisholm]

You may get some excellent responses if you post this question in the Yahoo "Homebrew_PCBs" group at < Homebrew_PCBs : Homebrew Printed Circuit Boards >.

Dale

[SY]

If your circuits aren't terribly complex with tight traces, Morgan Jones showed a nice cheap approach in "Building Valve Amplifiers." Enamel paint, a brush, a center punch, and etchant.

[richie00boy]

The etching solution will do several boards, don't waste it.

You will need a drill stand to hold the drill. HSS drill bits blunt in no time on PCBs so use carbide ones, a lot more expensive and brittle but take your time with the drill stand and it works out cheaper and better result.

I can't see you cutting boards with a jigsaw unless you have a bench mounted Hegner or similar.

[mcd99uk]

Maplin's press and peel sheet work well once you get the process right. Expect a few failures though. These sheets are good for small quantities of boards.

I prefer the photoresist route. Made my own "lightbox" using a couple of sheets of glass and an old sun lamp. Cheap but good enough to make flawless leach amp PCBs time after time.

I wouldn't use a jigsaw to cut the board. I either use a hack saw or I heavily score the boards with a knife and snap them.

[Minion]

If you have a Lazer printer try the Kodak Photo paper , it is practicly fool proof and for me is the Best photo paper for doing etches ......

Also a really cheap and extremely effective etching solution is 1 part Muriatic acid to 1 or 2 parts hydrogen peroxide ...... It is faster than ferric chloride and sodium persulfate and way cheaper , a Gallon costs you about $20 and lasts forever ......

Get a Dremmel type tool and use a cut off-weel for cutting PCB material , I use carbide Bits and use a dremmel to drill holes but a drill press might be better if yer hands aren"t steady .......

Cheers

[dchisholm]

For machining (cutting and drilling) printed wiring boards you can "get by" with with a wide variety of inexpensive tools, but if you make more than a handful of boards you'll probably want to invest in appropriate tools.
- The fastest way to cut simple rectangular boards to size is with a bench-mounted, or free-standing sheet metal shear. A small-time heating/air-conditioning shop may do the task for a small fee.
- A table saw with a high tooth-count carbide-tipped blade also works well. Cover the cut-lines with masking tape to improve the edge finish.
- An old-fashioned office paper cutter - the kind with a cast-iron (or very heavy wooden) base, and a pivoted-arm cutting blade weighing a few pounds, can also work if you put some muscle into the down-stroke.
- I have mixed success with the score-and-snap approach. It definitely requires a HEAVY score to get a clean edge - use a straightedge to guide the scoring tool. Using a sheet metal bending brake to do the "snap" is much better than trying to do it over a table edge, but you don't want to do this after etching.
- A steel file can clean up ragged edges, but only if there is enough remaining material to safely remove.
- Cutting tools (drill bits, sawblades, etc) really should be carbide-edged.
- If finished size is critical (tolerance tighter than about +/-0.10"), or if the shape is anything but a simple rectangle, rough-cut the board oversize. Then, carefully make an exact-size pattern from smooth-edged lumber and use a router with flush-trim bit to finish the job. (Double-sided "carpet tape" secures the pattern to the board during final machining.)
- Using a hand-held drill or Dremel tool I'm lucky to get more than a couple dozen holes before I break a drill bit. Even a stand-mount, or drill press, won't do much better if there is runout of the spindle, or much play in the quill. Lightly engaging the quill-lock (just enough to definitely feel resistance as you lower the quill) may help.

Dale

[roger_lew]

I'm by no means an expert. Though I have managed to pull off some pretty small double-sided PCBs. Hardest part with the double sided boards is getting them aligned. For me drilling some alignment holes seem to be more accurate than merely folding and slipping the boards in between. I founding ironing one side, then drilling the alignment holes, and then aligning the second side worked better for me.

Glossy magazine paper using the toner transfer method worked great for me. After ironing let it soak in water for a couple of minutes and the paper will come off alot easier. A sharpie can fill in imperfections.

I also second using muriatic acid and hydrogen peroxide, though I would warn that the fumes are intense. I would do it outside with a chemical respirator on and try to keep other humans and pets at bay. If you have control over the layout you can try to leave more copper on the board to conserve etchant.

I found 1/8" shaft carbide bits from ebay at a reasonable price. I also second using a press of some sort and something with lots of speed. I've found the bits are much more resilient at high rpm. If memory serves automated fab machines run them at ~50,000-100,000 rpm. I have a Dremel drill press and before I bought it I did some reviewing. Some people complained that it walks too much. But I didn't find it particularly hard to use, though I haven't used anything nicer. If you go the dremel press route tightening the plastic locking nut just about past the point you think it will break helps cuts down on the walking. I already owned a dremel so getting the press made the most sense for me.

For cutting I've also used a a table saw. Miter saw works too. I just cover both sides in 2" painters tape before cutting, and go slow.

Like I said in the beginning. I'm no expert, but I have found the whole process extremely gratifying. Chances are a couple of boards might bite the dust, but luckily the investment is in the tools and not so much the materials so screw-ups don't wind up being super expensive, just time consuming.

Roger

[seanvn]

In terms of layout I use MS Paint which is on nearly every PC. First use MS Paint to create a blank image. Save that as a .bmp file (the default) and open with the photo viewing software Irfanview. That has a option to change the DPI resolution of the .bmp file using Image-Resize/Resample Image. If you set the DPI to 50 that will give you a minimum trace width of 20 mils. Save and open again in MS paint. Check that the DPI resolution setting is correct by doing Control - E. Then 5 pixels =0.1 of an inch. Use Irfanview to print out the image, it has the option- Print Size - Original Size (from Image DPI). There are tutorials on the internet that can help you use MS Paint more efficiently.

[ChicagoJTW]

I have done extensive amounts of etching of copper, bronze and brass using ferric chloride (a salt). It is much safer than "muriatic," which is hydrochloric acid and water. You do not need to dump it after each use. Re-use it until it turns green or the etching slows unacceptably. It's best used with single-sided boards floating and turned upside down (cork or styrofoam glued on in the corners of the back side). For a two-sided board, placed on the bottom atop risers to allow circulation. A pump to circulate the solution is a luxury and probably not necessary. Gentle periodic agitation is all that is required.

As far as PNP goes, it's horrible stuff to get ironed on well--very tricky. For plain vanilla PCBs, why not get pre-sensitized boards and expose them instead of going through all the effort of cleaning and ironing?