Charlie made his own Bus Pirate PCB and used LPKF EasyContac rivets (warning, page denies non-US IPs) to connect the front and back sides. He had to enlarge the vias to 31mils to fit the rivets, and suggests going even bigger if possible. There’s more discussion on Charlie’s blog and at CNC Zone.
The LPKF ProtoMat PCB mill is also worth a look (this page accepts all visitors). That would be great in our lab!
Via the forum.
If you’re not in the US use Google.com with cache:http://www.lpkfusa.com/Store/ProductList.asp?Category=Through-Hole%20Plating%20-%20EasyContac . It works fine here in Germany…
The CNC I use is this one, http://www.accuratecnc.com/A560.html
I didn’t do a terrific job on that first board with the rivets, so i changed out to a V45 bit, padded a few tracks and recut it. They do work for under smd IC’s though, thats what i was really looking for.
Not sure what lpkf has got against us brits though !
cheers Ian.
Site works fine in Canada.
I have access to an LPKF and it has taken an oppressive and expensive amount of care, feeding and workarounds. I don’t know why this one has been such a PITA, but I kinda dread having to work on it. And all of the perishable accessories (from them) are also fairly expensive.
I’m looking into etching and using manageable-sized SMT parts to minimize drilling because of my experience with the mill. The mill seems like it should work great, but darned if I can figure out how people get them to produce boards reliably, unfortunately.
oppressive and expensive amount of care
Funny and apt description of a high maintenance tool!
Etching with 0805 SMD is my current method, with minimal jumpers on the second side.
I wish there was an inkjet that could print directly to a photo-sensitive PCB to apply the mask prior to UV exposure. I’ve seen some similar hacks in the past, but most try to use the ink as an etching mask (with limited results). I’d rather keep using photo-mask PCBs, but skip the transparency step and print the mask directly to the PCB for sharper lines. Bonus if the printer exposes the board as it feeds out the other side. I suppose the down side it that it would want to feed a whole PCB every time, right now I can use little scraps for small stuff.
Direct print of either mask or resist would certainly be nice. One thing that I’ve seen attempted with limited success is spraypainting their clad boards and then using a lasercutter to burn-off the paint. Still need a laser cutter though, and results have been mixed doing it.
Why is the transparency step such a problem? Seems like one’s only chance of getting top-to-bottom registration working is to do it manually, because such a “magic” printer probably won’t take care of that problem. Seems like such a “magic” printer could take a feeder like the 4″-6″ photo ones that are used for inkjets now (since we’re dreaming) for smaller runs.
From my own experience the single biggest problems milling have been Z-plane variations, and the mill I use even has the (optional) vacuum table attachment (which I’m guessing is $1000-2000 alone). I’ll be end-milling part of the board and it’ll be perfect and then I get six inches away and the bit barely polishes the copper to be removed. But if we run a strain gauge around the board to find the low point and adjust to that, the highest points on the board get milled so deep that entire traces get milled away from both sides.
It got to the point that I was changing my traces to 40mil just so I’d get 6-8mil of trace material left in the most deeply milled spots.
I’ve seen some pretty nice milling results elsewhere, but none of them are mine, that’s for sure. Hopefully someday we’ll get the thing working to the level at which it’s almost certainly capable of performing. But at this point, I don’t have a clue how much of an investment it’s going to take to get it there.
From what I can tell, it’s probably no different than the aggravation one goes through getting their pick-n-place machines working reasonably well.
IMO, your time has to be worth a lot to want to take on a mill, because it’s not cheap to acquire, use or maintain. All of the “perishables” aren’t cheap. Nor do you get plated-through holes and vias, just like all of the other DIY solutions. As far as I’m concerned, except in the case of the simplest boards, that’s the biggest PITA. I’m willing to drill, but I’ve found that there’s nothing less rewarding than building vias and PTHs by hand.
Personally i am working in a lab where we have the whole LPKF system, and i have everything working, including the Mill (Protomat S62 model) and the pick and place (protoplace) my problem however lies in the electroplating machine that we have been trying to use. does anyone know of the best way to get the same result as through hole plating, with small diameter holes, i’ve heard about riveting and using wires that are solderd through, but that sounds extremely messy and time consuming
Help would be greatly appreciated
Found the rivets on the swedish reseller solectro:
http://www.solectro.se/Product/Index/1063
And the price is somewhere about $800 (plus 25% tax i presume) for the simple tools and some thousand rivets. It’s INSANELY expensive, there must be an alternate product to buy?