PCB Milling Failure - Page 1
Forum section: electronics / projects

author: CJay
author_rank: Super Contributor
timestamp: July 28, 2017, 06:30:03 pm
content: First attempt at PCB milling today, using a Roland Modela MDX20 and it's not great.I know what one failure is, I didn't level the bed but the tool to do so wasn't there, it will be next time so the cutting will be level across the board and the unmilled pads should be fixed..Second fail, the cut edges are *very* rough, i suspect this may be choice of cutter and or feed speed.Third, the geometry, the lines aren't parallel and the squares aren't square, I have *no* idea what causes this except maybe slop in the cutter mounting/head?Fourth, scaling, it's meant to be for a minicircuits SBL-1, 0.2" between pins and it's off by a few thou over the length, not unworkable but not ideal.So, am I barking up the wrong tree with this machine and it's not suitable for PCB milling, is it worn out, am I doing something wrong, can I fix it?(And yes, I know the board design is pretty poor, it was done as a lashup for a test mill session)

author: DBecker
author_rank: Frequent Contributor
timestamp: July 28, 2017, 06:43:07 pm
content: That is laughably bad.There must be a significant amount of flex and lash in the mechanism. Software can reduce some effects by using a consistent feed direction and speed, but it can't generally work around soft mounting and chatter. Having both chatter and lash (free play) is probably unsolvable.

author: CJay
author_rank: Super Contributor
timestamp: July 28, 2017, 07:00:53 pm
content: I hoped I was wrong about the slop in the mechanism but that may be beyond my remit to sort if it is even possible to do so.It's a machine in a community workspace so I think it may be something that's been handed down from industry, as such it's probably worn out or in dire need of maintenance.Next time I'm in there I'll see if i can detect play in the cutter head and see if they'll let me do some maintenance.I'm interested to know if anyone has experience of the Roland Modela machines though, especially when used for PCB milling

author: Benta
author_rank: Super Contributor
timestamp: July 28, 2017, 07:20:51 pm
content: From what I've seen, it's an engraving/modelling machine, made for working with resin, wood, etc.It is not a milling machine, for that it's not sufficiently rigid.Using it for PCB contouring is taking it to its limits.That being said, PCB contouring should be possible, working at high rpm (20,000+), low cutter overhang and relatively slow feeds. Your jagged edges suggest far too low rpm and too high feed, making the cutter flex and "dig in" excessively. I also suspect that your PCB substrate is not being held tightly enough to the table.

author: rstofer
author_rank: Super Contributor
timestamp: July 28, 2017, 08:34:44 pm
content: That's a very expensive machine, I would expect better.How come the web site says FR-1 PCBs and doesn't include FR-4? That's a problem! It can cut phenolic but not fiberglass.Higher speed on the cutter and lower feed rates as mentioned above.Also mentioned and a likely problem is board mounting. It needs to be held really tight.

author: drussell
author_rank: Super Contributor
timestamp: July 28, 2017, 09:04:59 pm
content: Quote from: Benta on July 28, 2017, 07:20:51 pmEngraving machines need to be rigid to make proper engraved signs/plaques, etc. also.My old Dahlgren Wizzard XL (1980s vintage, dual Z80 processors) is still accurate to 0.001" with no issues, anything less is pretty much pointless...The internal CRT hasn't worked for years, I really should find a flyback for that...The ol' Commodore external monitor plugged into it still works just fine, though... LOLI've used it to mill and drill housings and panels even, though... something it was NEVER designed to do... It's hard on it but it seems to always just take it like a champ!

author: janoc
author_rank: Super Contributor
timestamp: July 28, 2017, 09:10:22 pm
content: The non-squareness of the square pads tells me that the frame of the machine is pretty much out of whack and that it is either loose or flexing and it depends on which direction it is going. The axes are certainly not square to each other by any measure.That needs to be sorted out before you can have any hope of using it even for just wood. It has likely been well abused and not maintained properly.

author: Benta
author_rank: Super Contributor
timestamp: July 28, 2017, 09:24:43 pm
content: Quote from: janoc on July 28, 2017, 09:10:22 pmI disagree. The odd shape of the square pads, plus the jagged edges indicate that the cutter is flexing, due to wrong speed/feed.If the machine is out of adjustment, the geometry errors would be consistent (eg, parallelogram shape).Play in the guides could lead to similar results, but would be more abrupt and not as consistent as these. Note that the pads look ugly, but are the same, play would be much more random.

author: DBecker
author_rank: Frequent Contributor
timestamp: July 28, 2017, 09:53:15 pm
content: If you look at the 'square' pads, you can tell quite a bit. The slope changes depending in which direction the cut was made, which suggests that the milling head is walking and/or the work piece is moving. The trapezoid shape indicates lash on top of the flex.It's common to reduce lash by always cutting in the same direction, commonly by putting the machine frame into compression or belts in tension. Tool walking or slow compression/flexing of the mount or work piece isn't readily handled.

author: CJay
author_rank: Super Contributor
timestamp: July 28, 2017, 10:06:39 pm
content: Well, I can go back tomorrow and try again, I won't have time to level the bed (the only way appears to be to mill away a sacrificial surface which takes time and a 3mm bit which is on order) so, comments on the below please?You're going to have to excuse me if I get terminology wrong as this is new to me.I've been thinking about how the machine works and the events of today, I now suspect it's mainly feed rate and the bit flexing as has been suggested.The reason I think this could be the case?The software defaults to a 20x20mm offset start position, sending the head to that position was repeatable after several resets of the PC and mill so, to my thinking, that would indicate the workpiece was fixed solidly and the guides etc. are fairly slop free and that the main problem I have is feed rate.

author: Benta
author_rank: Super Contributor
timestamp: July 28, 2017, 10:24:31 pm
content: QuoteDo NOT open this can of worms, unless you want a surface that looks like steel wool. Don't even think about it before you have your feed/speed rates worked out! Jeez!What you need to do is provide data instead of lamenting.Cutter type? Size? Length? and, and, andSpeed?Feed?Spindle bearings OK?Play?Pictures, especially of the cutting head.We're all groping in the dark, because we have no information!

author: G0HZU
author_rank: Super Contributor
timestamp: July 28, 2017, 11:00:21 pm
content: Wow that looks bad... At work we had a new T-Tech 7000S machine back in the 1990s that we foolishly let all the engineers play with. It took maybe a year for it to get ruined through ignorance and clumsiness resulting in several bed scores and knackered spindle/bearings with obvious out of true in the spindle. Even when it was like this I think it could still outperform what you have there. Maybe if it was also used with a faulty/worn tool it would produce the churning effects at the edges too.But your board even has wandering on the squares that have only scored the surface of the copper.Here at home I have a 23 year old T-Tech 7000S and its a similar model to the one we had at work. It is all original and see below for a recent closeup of a simple SMD board on FR4. This was done using worn tools that were salvaged at work when they reach the end of life in terms of distance milled. Had I used new tools it would have looked better. The traces are typically 0.012" and the SMD part in the centre is 0805. Your machine isn't designed for PCB milling so won't be able to match this but I'd expect it to get reasonably close.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: July 28, 2017, 11:38:23 pm
content: Hi,It looks very bad. I have an LPKF c60 Protomat and I get much better results than that.I use tools from Think & Tinker Ltdhttp://www.precisebits.com/applications/pcbtools.htmFor milling traces is use EM2E8-0625-90V, this is a 90 degree carbide cutter. The spindle speed is around 30,000 rpm.I use regular FR4 material. The LPKF is equipped with a Nilfisk hepa vacuum.Here is a board that I milled on the c60:Good luck!!Regards,Jay_Diddy_B

author: brainwash
author_rank: Frequent Contributor
timestamp: July 28, 2017, 11:54:22 pm
content: I don't have on-hand experience but agree with most of what has been said already.First off you need to have the right cutter, right spindle speed, right feed rate and right depth of cut. For PCB the standard (AFAIK) cutter is a carbide one. They need to run fast (>>20k RPM) and feed relatively fast and have absolutely no flex.You can try feeding them slower but they will burn out quicker. If you feed them fast at low RPM they will flex and break instantly into shards.If you insist on using the same cutter, I would suggest trying to do it in two or three passes, at maximum RPM. For small diameter drills you need to spin them really fast. Slow down the feed rate to 1/10 of what you have now and work your way up. I would suggest redesigning the CAD so you have rectangles with different feed rates and see which one provides the best compromise.Regarding the machine, it seems adequate for the job, I've seen much worse machines perform better.Work piece leveling is a must, level the bed first and then clamp the board as good as you can. Invest in a dial/digital indicator, if you don't have one, they run for 20$ including the magnetic base.Last but not least, invest some time into some machining books or watch some YouTube channels. oxtoolco, Stefan Gotteswinter and Robrenz do precision work and there's always something to learn from any of their videos. Even 4h invested in learning will save hours of frustration and $$$ in broken tools.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: July 29, 2017, 12:17:41 am
content: Hi,Here is another picture of a different board.It shows an area for a SMD part. The lead pitch is 0.5mm or 0.0197 inches.The board was cut on my LPKF c60.After machining, a light sanding with 600 grit wet and dry paper.I think that the cutter is too deep on your original pictures. it may be too sharp an angle. Can you post a link to the bit that you used?Regards,Jay_Diddy_B

author: drussell
author_rank: Super Contributor
timestamp: July 29, 2017, 07:10:29 am
content: Quote from: Benta on July 28, 2017, 10:24:31 pm+1 for spindle bearings being worn or something else being loose somewhere causing the obvious sloppiness....

author: CJay
author_rank: Super Contributor
timestamp: July 29, 2017, 08:07:16 am
content: OK, lots of useful info and some rather enviable boards from Jay Diddy B, suitably impressed.I have to admit to not putting too much thought into this because I was assured by the people who run the group that they and other members have successfully made PCBs by following a user created guide sheet for PCB milling, so, from that I got:1. Cutter, 0.4mm2. Feed rate, 4mm/s3. Cut depth 0.045mm4. Guide recommends 1.25" of the cutter is left out of the spindle, I think it's flexing, will reduce this.Pictures later.Spindle speed of the machine is 'only' 6500RPM, could that be used with a carbide bit if the feed rate was set appropriately low?PCB material is SRBP, not tough to cut.After reading the replies here, examining the board made yesterday and thinking about it all:The distortion in the squares is repeatable and varies reliably depending on feed direction, bottom row was left to right, 2nd row was right to left, 3rd L-R etc... I think this suggests the guides and frame are OKPlay in the spindle, I *think* it's OK, I couldn't detect any by hand but I need a dial guage to check properly and I don't have one, I can borrow one next week though.I am coming to the conclusion that feed rate and a crappy worn out cutter are the main problems so today I'm going to try lower feed rates, down to impractically low rates if that helps make square squares and then decide, based on advice here, if I should order some carbide bits or if I should give up.I can't repair or service the machine as it's not mine so further time and any money spent would be a waste if I can't get better results from tinkering with the things I can control.

author: Siwastaja
author_rank: Super Contributor
timestamp: July 29, 2017, 08:44:36 am
content: Quote from: CJay on July 29, 2017, 08:07:16 amThis is way too low, no chance of it ever working. You can achieve 20-25k rpm easily using sub-$100 Dremels and similar.

author: CJay
author_rank: Super Contributor
timestamp: July 29, 2017, 08:56:51 am
content: OK, so it's a bust then.Thaks for all the help. Will pursue other methods for prototyping, back to the chemical tanks probably.

author: Siwastaja
author_rank: Super Contributor
timestamp: July 29, 2017, 05:50:35 pm
content: Both opto-chemical process and milling can produce good results, and both require skill, practice, specialized workplace and some investment in tools & materials.IMHO, however, milling is often way overrated (treated as a simple, turn-key solution, what it isn't) while the chemical process is way underrated. For some odd reason, it seems that it's hard to discuss in civil (non-aggressive) ways; I guess people might have issues with the concept of needing "chemicals", and they like theconceptof fully automated, one-step manufacturing so much that they tend to sometimes get religious about it. (edit: this is not in response to anyone in this thread.)I've done a lot of PCBs by etching, and at 8/8 mils tracks/clearance, the copper quality is almost on par with commercial manufacturers, it's just lacking plated-through holes, high-quality soldermask and of course, multilayer.On a limited budget, chemical process will get you way better copper resolution per money. A good etch tank and UV exposure unit are at least an order of magnitude easier and cheaper to build than a good CNC mill.OTOH, for drilling the holes, you most likely still need some kind of CNC machine anyway, although a lot simpler machine with mechanical play that would never produce acceptable milling results, will suffice for drilling holes at exact locations, especially as you can compensate for mechanical play in software by approaching each hole from the same direction. Many of the "cheapo" DIY CNC kits arealmostable to do high-quality CNC milling, but not quite; whereas they are more than enough for CNC hole drilling. For hole drilling, the base doesn't need to be leveled and the workpiece mounting is trivial as there are no sideway forces.Since the chemical process requires so many seemingly tedious steps that each take some practice to perform correctly, not to mention the need for separate CNC drilling step, I understand very well why PCB CNC milling looks so appealing. But as usual in engineering, it's completely different to imagine a technical need or concept, and to provide a really workingimplementationthat matches the expectations. PCB milling is often unsatisfactory on hobbyist budgets. For professional sector, some machines perform better, others require a separate operator to be hired in practice due to maintenance-requiring or hard-to-use design; I've heard from several professional sources that the LPKF machines have been especially painful and disappointing in this regard as they didn't provide the turn-key simplicity they were bought for, although, this might have changed with the company feedback and design of new models.

author: brainwash
author_rank: Frequent Contributor
timestamp: July 30, 2017, 01:39:05 am
content: Quote from: CJay on July 29, 2017, 08:56:51 amI personally wouldn't give up so easily, there's a lot to be learned from failures. If you can spare a few cutters (I assume cheap and/or HSS) then go with max spindle rate and lower depth-of-cut, keep the feed rate the same. Your tracks are both skewed = high feed rate vs. DOC and chewed= high DOC and/or worn cutter. If you see older videos of semi-commercial CNC PCB router machines, they do at least two passes.I would advise against Dremel for CNC - some clones/variants use bushings instead of bearings and even with bearings they have a lot of endplay, as opposed to a true pantograph setup (like your dentist uses).If nothing else, seek help from a machinist near your location. But bear in mind that commercials setups use mostly chemical etching.

author: CJay
author_rank: Super Contributor
timestamp: July 30, 2017, 08:51:33 am
content: I've all the equipment for UV processing and chemical etching, I was just hoping I could prototype a few by milling and then perhaps outsource them to a Chinese fab.Seems it's nowhere near as simple as I was lead to believe it was 'point and shoot' by the guys who run the place.I have already booked lasercutter time so i'm not going to give up on on the mill completely, it's a handy machine even if it's not useful for PCBs.I do think it wouldn't be the end of the world if I bought a couple of cutters to play with so if i can find some suitable i might add them to an order.

author: colorado.rob
author_rank: Frequent Contributor
timestamp: July 30, 2017, 03:15:19 pm
content: I don't get the need for doing pcb etching or milling these days. You can get a properly fabricated pcb for next to nothing with quick turn-around. Hell, I just got 20 4-layer pcbs (5/5 & ENIG) prototype boards for under $100 in a week. A 2 layer 6/6 HASL run would turn around quicker and cost significantly less.

author: tooki
author_rank: Super Contributor
timestamp: July 30, 2017, 03:35:37 pm
content: …because you need it in a few hours, not a few days?

author: Siwastaja
author_rank: Super Contributor
timestamp: July 30, 2017, 05:03:25 pm
content: Maybe, just maybe, therearesome reasons for it, and maybe you could try to spend a little bit of your mental resources first trying to think about it for a second, or maybe search for the gazillion previous discussions, instead of requesting that we need to spell it out to you, each and every time.People who have desperate need to fill up any DIY PCB fabrication related topics with their questioning about its point are the cancer of this forum. Bravo, this was the first and it took 21 posts before it happened. Maybe the situation is improving? I remember when it was everyday business thatanyDIY PCB fab related question was buried under dozens of echo chamber posts about how ridiculous it is.Hint: One of the reasons is totally obvious and in plain sight for anyone not a complete idiot; but there are several subtle and deeply meaningful additional reasons, too, why we do (or did) it.

author: KL27x
author_rank: Super Contributor
timestamp: July 30, 2017, 09:21:30 pm
content: QuoteWith toner transfer, there are only two chemical tanks. The etch tank and the bucket of water. Maybe give it a try. I keep my etch tank outdoors, filled with cupric, and evaporation is very minimal even in summer.The etch tank itself is built to last a lifetime. After many iiterations, I have found perfection in a vertical etch tank. 3 plates of plexglass. The middle is cutout into a u shape, and all 3 plates are stacked and drilled to take nylon bolts all the way around the sides and bottom. A wood exoskeleton is drilled and countersunk for the nuts and bolt heads. The plexi is roughed up around the edges, sealed with silicone, and after it is dried, the skeleton is bolted on to provide constant tension on the joints. Everything is UV and weather resistant. Direct sunlight is not a problem. A lid is made with the plexiglass scraps, which makes evaporation insignificant.The bubbler is a length of bubble "wand." I have used the same piece for over 7 years, now. It doesn't dissolve or clog (at least not with the air compressor I use, lol). It is over 1/4" thick hollow down the length, so it doesn't clog, and the bubbles are very, very fine.The board holder is a key problem area which can make things more difficult than they need to be. My solution is a sheet of foam board. Using nylon bolts/nuts, you can make a clamp at one end to hold the board by the top edge. Then using heat gun you can bend two strips of foam board into 90 degree brackets which reference the holder to the top of the tank. Two more nylon bolts/nuts are used to adjust the height of the holder/board in the vertical tank. Both sides etch at once with no impediment; the bolt heads one one side of the clamp and the nuts on the other keep the board centered in the tank, away from the walls. And you don't have to touch etchant or fiddle with strings. You can pull the board out for inspection at any time and put it back in.The only thing that has required some maintenance is the secondary air regulator that goes to the tank. Corrosion has caused it to seize after a few years. This might be because the one-way filters die/clog and I stopped using them. I have had to take it apart and clean/buff/grease it a couple times. Lately I just left it to seize up at the perfect spot, and I don't adjust it anymore.The pancake compressor I use only turns on for 10-20 seconds every 45 minutes or so. It doesn't take much to get maximal aeration/agitation. Only about 20 psi, tops. And this is light years ahead of fish tank bubbler diaphragm motors.If you dedicate your efforts to improving the setup, toner transfer is extremely simple and effective. For anything down to 8/8, it is very hard to beat, IMO. $100.00 and a few hours on the tank. Another $60.00 on a laminator and heat gun. The laser printer is another $100.00, if you don't already have one. A suitable air compressor is another $100.00. If you don't already have some of these things, you are going to find most of these things quite useful for other things, too (except maybe the laminator). So maybe give a go at using CNC machine to improve your toner transfer tools. And save your cutting bits in the future for routing the board edges and making holes, rather than watching machine cut copper clad for hours at a time after 20 minutes of fiddly setup.

author: G0HZU
author_rank: Super Contributor
timestamp: July 30, 2017, 11:02:34 pm
content: QuoteI do think the mill is a good option for prototyping simple RF boards, especially double sided boards with custom outlines and cutouts. This is where it will be very fast, especially if you want to try several subtle iterations the same day. But where it gets bad very quickly is if the board is big and complex with lots of narrow circuit traces to mill as on a complex digital board. It then becomes very time consuming and expensive to mill it especially if the operator makes a mistake and has to start again. The advantage with etching in this case is that the complexity of the board doesn't really affect the production time in the same way it does for milling.However, if I went to work tomorrow and suggested we go back to etching our RF prototype PCBs (after >20 years of milling success) I don't think I'd convince many people. Even if I did the complaints about the chemical smells in the workplace (especially in the summer) would soon put an end to it.Both milling and etching have their own advantages and disadvantages and therefore there isn't a simple answer as to which is best. It will depend on the requirements of each individual

author: hermit
author_rank: Frequent Contributor
timestamp: July 31, 2017, 12:24:09 am
content: Quote from: Siwastaja on July 30, 2017, 05:03:25 pmI just helped someone on another forum with a PCB layout problem. For reasons unknown his chip was offset at an angle and that was causing problems. I didn't ask him if he could rotate the chip. I assumed if it was rotated there was a reason so I helped find the solution to the problem he asked about. I admit when I was younger the first answer out of my mouth would be "Why don't you just do it the way it makes sense to ME." I finally came to realize it was simply my arrogance. I didn't see it as such at the time of course. What is the most disturbing is when people on a forum like this just don't seem to get the desire to do/learn something for themselves. Maybe you learn to plan ahead so you can order that board 10 days before you need it. That's OK too.

author: drussell
author_rank: Super Contributor
timestamp: July 31, 2017, 04:04:08 am
content: Quote from: Siwastaja on July 29, 2017, 08:44:36 amBAH!No way... This is only a PCB! The RPM isn't going to matter. Unless you have a retarded amount of slop in your spindle, you could have the spindle almost completely stopped with a dull-ass bit and you'll still get a good PCB.Do you have any experience with engraving machines?I can stick a diamond graver (that would running at the high speed of 0 RPM, by the way, for those of you who don't know engraving) in mine and scratch out lettering all day long on brass or steel or glass or stone or any other material and it won't care one bit. Still accurate to the 0.001"Any flex is coming from something wrong with the machine if it is intended to do this stuff with any kind of accuracy. (and it SHOULD be... that is trivially easy!)I could always pull out a piece of FR4 and make a vidjeo, I suppose, if you don't believe me...What do you want? 1000 rpm? It'll still cut straight lines, they just might not be as fully smooth at the edges if you crank up the linear surface speed with too low of a cutter RPM, and it will be hard on the bearings, leadscrews, steppers, etc. but it will absolutelyNOTmake silly squilggly lines unless your machine is either completely not fit for purpose or has someextremewear.P.S.SPINDLE BEARINGS... SPINDLE BEARINGS!!!

author: CJay
author_rank: Super Contributor
timestamp: July 31, 2017, 09:10:10 am
content: Quote from: colorado.rob on July 30, 2017, 03:15:19 pmBecause I want to be able to prototype things rapidly, I don't want to have to wait a week and spend $100 to realise I got something wrong or it just doesn't work laid out that way, I'm not a design genius who will achieve perfection on the first attempt so the ability to make a board and fix problems on it in a few minutes is invaluable to me.If I were to do that by sending out to a fab with a week lead time it could take months for me to get it right and cost me a significant amount of money, time and money that would be far better spent on designing/testing/developing and buying components IMHO.If/when the mill works for me I can run several iterations of the entire process in a day. I can also do the same with the etch tanks I have buried in storage but they will take more room and are messy so the mill would be an ideal technology.Once I've finished messing about developing a circuit and board I can send it out to a fab and get back a HASL board with beautiful silk screen and soldermask but until I'm sure it works I don't want to waste my precious time and money.There's also significant pleasure in having actually built something, it's the difference between cooking a meal from scratch and buying a ready meal to microwave.

author: janoc
author_rank: Super Contributor
timestamp: July 31, 2017, 02:48:42 pm
content: Quote from: CJay on July 31, 2017, 09:10:10 amThese "why do you make your own boards when you can pay $$$ to have them in X days" folks tend to forget that not everyone has this stuff paid by their corporate credit card/accountAnd that a lot of people, especially in Europe, don't have a quick turnaround prototyping service around the corner that will:a) talk to you if you don't have a company account,b) not charge you an arm and leg for a small job.$100 is not a trivial amount to pay out of pocket for a board, especially if not sure whether or not it will work on the first try. I am not saying it is expensive (esp. for a 4 layer board where one doesn't have the choice anyway), but it is not the kind of money I will just throw around on a whim.

author: medical-nerd
author_rank: Regular Contributor
timestamp: August 01, 2017, 11:42:36 pm
content: HiyaThis past weekend I discovered that I canhandmill simple stripline circuits on FR4 using a PROXXON MF70 after a couple of hours of practice.I'm just starting with this using a 1mm bit and an excessive depth, but the satisfaction of using something like this in a circuit I'm prototyping is unbelievable.Cheers

author: cdev
author_rank: Super Contributor
timestamp: August 01, 2017, 11:52:09 pm
content: I am hoping to be able to do that soon with my drill press and a (really) cheap x-y table I just ordered. I'd be interested in hearing more.The X-Y table I just ordered has got to be one of the cheapest ones out there. Its bright green, you probably know the one. Its the $30 one, not the $60-70 one.Its my understanding that it can be improved significantly by disassembling it, cleaning it really well and then relubricating it with high quality grease.At the very least, it will help a lot with drilling vias evenly.

author: medical-nerd
author_rank: Regular Contributor
timestamp: August 02, 2017, 12:02:15 am
content: HiyaSince its a Proxxon machine I started using the Proxxon 3 Piece Tungsten Milling Cutter Set:Double flute cutters made of solid tungstenClockwise cuttingFishtail profile ensures cutting to the centreUsable on cast iron, hardened cast iron, steel, brass, aluminium, glass, plastics and carbon fibreOne of each: 1.0, 2.0 and 3.0mmShaft dia. 3mmI'm looking for smaller bits suitable for PCBs but the ones I have found so far are in USA and although they are only £6, postage is £42!!Cheers

author: cdev
author_rank: Super Contributor
timestamp: August 02, 2017, 12:34:35 am
content: That doesn't sound right. You're just a few hours away.Never say die.So, you're using the one on the left for the smallest cuts and I am assuming the big drill body is for stability.. makes sense.If you live in a country where you can buy hydrogen peroxide - you can also use (toner transfer and)hydrogen peroxide, vinegar and regular table salt(!) to etch PCBs.It works fairly well, its also fast.

author: tautech
author_rank: Super Contributor
timestamp: August 02, 2017, 12:55:48 am
content: Quote from: KL27x on July 30, 2017, 09:21:30 pmYou certainly have.For a few $ you can buy a roll of plastic gutter leaf guard, cut a length ~2.5 times the depth of your etching tank, fold it in half and use it as the PCB carrier.Something like this stuff:

author: brainwash
author_rank: Frequent Contributor
timestamp: August 02, 2017, 12:58:27 am
content: Quote from: cdev on August 02, 2017, 12:34:35 amThe collet likely accepts only a limited diameter range of bits. In fact so, they list that on the machine description. There's no other way to fit smaller bits in there other than getting a collet adapter. They can be ordered cheaply from the usual suspects (ebay, alibaba) but don't have the precision or balance for CNC work. With such an adapter you can use PCB drills.Fun fact: I have such an adapter that I use on my Dremel knockoff as well as on an electric screwdriver, with a 6mm hex to chuck adapter. The 'Dremel' has 0.1-0.3mm runout, the screwdriver with the chuck around 2-5mm(!). Running them slowly I could drill 0.2mm holes into PCBs without breaking the bit. I drill intro FR4, the copper just surrounds the via holes. Used only a handful of times, not sure how feasible that is.I'm surprised they work at all, considering I got a 0.1 to 1mm set for <4$. They're probably not hardened and can take a bit of flexing, the advantages of cheap tools...

author: KL27x
author_rank: Super Contributor
timestamp: August 02, 2017, 03:33:23 am
content: QuoteMeh. I think you overestimate how hard it is to machine and heat bend foam board. You get a holder that hold the board rigidly in the center of a 3/4" thick tank. To let the board drip dry, I just pull it up, set the board-in-holder at an angle so it rests in the top of the tank and drips down one corner of the board back into the tank. And then it gets plunged straight into a bucket of water. And especially in a vertical tank, it's important to be able to easily adjust the height as the level of the etchant goes up/down thru evaporation and addition, as well as adjusting for the height of the foam head (which also etches, in case you have a large board). This takes 15 minutes to make, and my "router table" is mini proxxon rotary tool like a dremel, for cutting the height adjustment slots. I don't want mesh flopping and dripping about. If you're gonna build a vertical etching tank from scratch, you can do a lot better than that.The clamp that holds the board is two pieces of foam board and two bolts/nuts to clamp the board between. There's just a small strip of 0.062" FR-4 glued between the other side of the clamp to keep the jaws of this basic vice at least parallel if not angled inwards, to maintain "vice-grip" on the top 2 mm of the board edge. Literally, this takes 10-15 minutes to make and is great. The overall thickness of the 2 sheets 1/8" foam board, the FR-4 spacer plus the 1/4" boltheads and nuts just happens to barely clear the inside of my tank (I had to grind the nuts down a tad, actually), keeping the board held rigidly in the middle of the etchant, centered over the bubble wand.Foam board has solid faces, but is just closed cell PVC foam in the middle. It machines like styrofoam. It bends from heat gun quite easily. The only drawback is I chose black... I can't leave it in direct sunlight or it will bend.

author: tautech
author_rank: Super Contributor
timestamp: August 02, 2017, 04:10:22 am
content: Quote from: KL27x on August 02, 2017, 03:33:23 amHere's mine, knocked up from stuff I had lying around.Base: plastic road markerTank: custom thermoformed 150mm waste pipe(using large propane torch and timber and wedges to get to flat form)PVC solvent adhesive for plastic gutters.Bubbler tube (not visible): extruded (straight) semi soft plastic tube, multi pierced with a stiff needle (fine ground file tang)PCB holder: folded gutter guardFits 220 x 150 mm PCB. 750 ml etchant capacity.

author: KL27x
author_rank: Super Contributor
timestamp: August 02, 2017, 04:37:53 am
content: ^That is insanely awesome.From my own experience, I feel like for tank 12" or less in width, the aspect ratio should be at least as tall as it is wide, if not a bit taller. To contain the froth/foam/spray, and to give space between the bubbler and the bottom of the board.I definitely like the simplicity of your tank. But I imagine you should need a brace to keep it from bowing out if you go any taller and/or thicker.Here's mine:It's made from 3/4" plexi for the middle sheet and 1/4" for the front and back sheets. 12"x12" plates, so you can figure the internal dimensions and volume from that. Suffice to say, it's a bit bigger than yours. The exo-frame is 3/4" plywood, for reference.PVC foam board and nylon hardware for the adjustable board holder:It holds the board tight, even when I do 0.007" FR-4.The greatest thing since sliced bread is this. You need to try this. Superfine bubbles. 7 years. Going strong.https://www.amazon.com/dp/B00J58YX5G/ref=asc_df_B00J58YX5G5103608/?tag=hyprod-20&creative=395009&creativeASIN=B00J58YX5G&linkCode=df0&hvadid=167154348866&hvpos=1o3&hvnetw=g&hvrand=16412591755102349002&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9030076&hvtargid=pla-316279230915*BTW, that's very daring of you to run your air line through the bottom of your tank, lol. Mine stays filled 24/7/365. I run the air line from the top. And it's also how I can remove and replace the bubble wand, if ever necessary. The tube is all that's holding the one end down to the bottom of the tank. (There's a kind of tubing I found which appears to be thick polyethylene. Fairly rigid; it must be straightened out with a heat gun. It is same ID as the rubbery airline tubing.)**In the top pic where you can see the height of the board holder is at from my last etch, you can see approximately how much higher the level of the etchant gets when the bubbler wand is full of air and the etchant is supercharged with fine bubbles from the air compressor.

author: tautech
author_rank: Super Contributor
timestamp: August 02, 2017, 05:38:04 am
content: I saw your description a few posts back and the pics match what I had in my mind.I looked at various configurations online over the years and knew a etching tank could be made simple........with the tools I had on hand. The tank forming was the tricky bit and another set of hands were used at the time but I did start of with a smaller version made from 100 mm plastic pipe. It takes a while to get enough heat into the tube to get it truely plastic to where you can form it flat especially if you don't want it marred with excessive heat from the torch.The bubbler tube was an accessory with a animal remedy pack and had a 8mm tube threaded bulkhead fitting on one end so with a rubber gasket I was fairly sure it wouldn't leak especially as the edge of the tank where it's drilled to pass through was flattened with the wedging from the forming. Sadly the nylon fitting nipple where a tube would push on didn't like this application and fractured outside the tank, where today I just push a tube inside it now and connect to the flow controller (thumbscrew) of an aquarium bubbler. You don't need a lot of flow, just a small steady stream of bubbles.The tank face that meets the base need be trued so that the solvent/glue can do its work and this I did with a hand wood plane. PVC pipe clear solvents aren't up to this, the surface area is too great and they don't handle the thermal cycling of warm etchants. Instead I used a dedicated Gutter glue/solvent that has proved to be much more reliable.As far as wall thickness is concerned and general robustness, the base is ~3mm but the tank is ~5mm (less for 100mm pipe) so when they are glued as one they add strength to the other part.

author: KL27x
author_rank: Super Contributor
timestamp: August 02, 2017, 05:46:22 am
content: Your tank reminds me of my proof of concept. I used a 2L bottle. I cut the top off, stuck just the right size book into it, and then hit it with the heat gun.I beg to differ on air pressure/flow. If you use cupric chloride, anyhow, the more the better... BUT you need a really fine bubbler to take advantage. This particular bubble wand makes super tiny bubbles. If you use an average air stone - or worse yet just melt/drill tiny holes in a tube - higher PSI would be worthless; all you'd do is splash/spray etchant. The largest air bubbles you would see in the liquid fraction of my tank are (much!) smaller than the CO2 bubbles that form in a glass of soda with a hair stuck in the bottom. You won't see a bubble even approaching half the size of a BB in the liquid fraction. In fact, unless you're within a foot away from the tank, you probably can't see the bubbles, at all (not including the head). It takes a long time for these tiny bubbles to rise to the surface, and the volume of air in the liquid is quite high. I do not even bother with a heater. Even in winter. Albeit, winter here is like high 40's.

author: tautech
author_rank: Super Contributor
timestamp: August 02, 2017, 06:58:23 am
content: Quote from: KL27x on August 02, 2017, 05:46:22 amI know you do.Like yours mine too has very fine bubbles, I purposely made fine needle holes to get the bubbling action fine AND to not have such great airflow as to cool the etchant too quickly. I was using Ammonium Persulphate back then and it needs be hot. My focus was only to remove the bubbles formed by the etching process in order to obtain more uniform etching (and some mild agitation), it did and also created greater problems with toner transfer porosities.ATM there is plenty of additional airflow available from my tiny aquarium pump if needed.Yes, for cupric chloride some greater airflow than I have now might be beneficial.

author: KL27x
author_rank: Super Contributor
timestamp: August 02, 2017, 08:09:46 am
content: QuoteLOL, I don't want to turn this into an argument. But needle holes are not particularly fine. At least, not how I have tried it. The smaller you try to make them, the more you end up getting all the air coming out of just one or two holes, lol. I dunno how the bubble wand works, but it's strangely good at making tiny bubbles. You'd think they would coalesce and form bigger bubbles on the surface, but it is like magic.Maybe I'm saying it wrong. It's not so much high volume of air that is needed to achieve this, but you do need much higher pressure than an little diaphragm pump fish tank bubble to push out a good amount of air through a bubbler this fine. I'm not talking about making your etch tank splash and make a mess.The lower arrow shows the level with the air off.The higher arrow shows the level when full of these tiny air bubbles. This is at a fairly low setting. (My regulator is sticking.... I can turn it up, but then I can't turn it back down without taking it apart.... so I don't wanna make a prettier pic than this). If you look real hard you can perhaps detect a vertical band of (very fine) bubbles in a stripe about 1/3 the way from the left edge. This column is rising (gently, as you can see in the very minor disturbance of the foam/liquid line). Everywhere else in the tank, the bubbles are going down with the gentle draft in the tank... they're that small. You could fit maybe 20 of them in a bubble the size that forms on the side of your glass of soda. I can't even get the bubbles to show up in a picture. I can't see them unless my face is close to the tank.I have built more than a few tanks and used different bubblers. These wands (and the pressure to push a good amount of air through them) are the greatest single improvement you can make to a cupric chloride tank. Beats the crap out of a heater, even. IMO.This works wonders for cupric chloride. Apparently the purpose is different for ammonium persulfate. For cupric, you generally want maximum air to etchant contact to oxygenate copper I to copper II, which means more and smaller the bubbles the better.This is the kind of bubbler that is supposed to make a thin sheet of fine bubbles, like a curtain, in the front of a fishtank. At lower psi, anyway.

author: CJay
author_rank: Super Contributor
timestamp: August 02, 2017, 08:24:55 am
content: Moving away from the milling discussion but I have a commercial etch tank with heater and agitation, it's been used with Ferric Chloride all its life and I've not used it myself for an awfully long time (horrible stuff FeCl) so it'll need a damn good clean out if I'm to use it again which makes the idea of a new tank rather attractive.I was told a long time ago that the best commercial systems of the time used continuous flow of etchant washing over the board, is this still the case?Are there videos of commercial etch equipment in action?(I could google but *everyone* who sells the equipment or PCBs will claim theirs is best)

author: KL27x
author_rank: Super Contributor
timestamp: August 02, 2017, 08:44:21 am
content: QuoteHave you seen this? It sure is Purdy.https://www.eevblog.com/forum/manufacture/p-c-b-foam-etching-machine-without-nozzles-or-air-stones/Before building my tank(s), I researched and for $250ish you can buy a professional vertical etch tank made of polypropylene (which is roughly 2 feet W by 1 1/2 foot tall by 4" thick... and probably takes a gallon or 3 of etchant!)There are spray etchers, as well. But honestly, I doubt very much they use this kind of etcher in mass production. It takes up so much space and makes so much fumes. They probably just use lots of bubbler tanks crammed into same space, perhaps with a central aerator/pump to recharge/cycle etchant from a larger reservoir, to do high volume etching with less fuss. You can only put in and take out a board so fast, anyway, and there are other bottlenecks/space-requirements in the pcb fab process. The spray etchers are probably more for fast prototyping labs for doing one-offs. While high paid engineers are on the clock, waiting.Reason I'm happy with my solution is that it takes no fuss. Put the board in. Come back later. The undercutting is so minimal, I have never set an alarm or timer. I just come back later. It is not the fastest sans any heater, but the maintenance is very minimal and the etch comes out very accurately, albeit slower, even when it's 50 degrees out. I might only use it 4 or 5 times a year, but it is always ready to go, and it doesn't leak. I am not sure where I'd put the over under on it, but I wouldn't be surprised if it is the lasted up until the wood frame rotted. Due to the construction, it would be easy to rebuild, if necessary. I was gonna say it is probably the last tank I'll ever build... but Tautech's tank is so cool I might have to make one for myself.

author: CJay
author_rank: Super Contributor
timestamp: August 02, 2017, 10:01:37 am
content: Quote from: KL27x on August 02, 2017, 08:44:21 amWow, yes, I like that and so relaxing listening to the etchantQuote from: KL27x on August 02, 2017, 08:44:21 amI was gifted an RS etch tank with a generous quantity of anhydrous FeCl (it was disposed of when I put things in storage), the only thing I've had to pay for is the electricity to run it.Quote from: KL27x on August 02, 2017, 08:44:21 amI had problems with undercutting on heated etchant if I left it for too long, etching in heated solution was under ten minutes usually with fresh FeCl IIRC but I did manage to forget one board and I found a plain sheet of fibreglass with the etch resist floating on top of the etchantI found UV exposure, developing and etching to be a *very* satisfying process, getting from the back of an envelope to a working prototype in a day was guaranteed to make me smile.

author: brainwash
author_rank: Frequent Contributor
timestamp: August 02, 2017, 10:24:31 am
content: I just put some disposable gloves on, use a kitchen sponge and rub the board with little pressure and etchant. It takes <5 minutes and I can avoid or insist on some areas, as the result is always visible. After a while the sponge will be corroded and will need to be disposed, but other than that it's as environmental-friendly as it can get with ferric chloride.

author: CJay
author_rank: Super Contributor
timestamp: August 02, 2017, 10:35:15 am
content: Nice idea, but TBH, if I go the chemical route again I won't be using FeCl, I'll go with persulphate, I've fond memories of etching my first PCBs and several hundred in a batch when a supplier let us down but FeCl is horrible stuff and I'd rather avoid the problems it has.

author: cdev
author_rank: Super Contributor
timestamp: August 02, 2017, 08:14:12 pm
content: Ever try a cheap aquarium air pump and tube blowing bubbles? (for agitation)It keeps the liquid moving.Quote from: CJay onTodayat 02:24:55

author: KL27x
author_rank: Super Contributor
timestamp: August 03, 2017, 03:27:24 am
content: QuoteThis is reason to keep it simple. Leave the crazy spray etchers for niche use. If something can go wrong, it will. If you have good setup, you should never have to suffer from "nasty ferric" issue. You might want to minimize handling of the etchant. If you have a professional tank that needs to be emptied and cleaned when it's not in use, and you hardly ever use it, you might be overcomplicating things. Maybe what you really want is a simpler solution.I see vid of DIY spray etcher. Watching the guy turn valves and press buttons and setup drain/waste buckets while wearing waders and eye goggles, and then proclaiming 3 minutes etch speed is ermm. well. Congrats, but I see 15 minutes setup, 15 minutes cleanup and tons of space for storage of the 5 gallons of etchant and the huge machine and the various buckets and cleaning gear you will need to have on hand to operate this thing. Fast etch is fine, but standing there and watching a board etch is only entertaining the first few times. After that, it is the same thing as watching paint dry. The etch speed is a small part of a much bigger equation.

author: Siwastaja
author_rank: Super Contributor
timestamp: August 03, 2017, 08:24:24 am
content: Air bubbling is enough to provide rather good resolution (down to 8/8 mils) and shortish etch times (down to < 10 min), although it needs to be a rather strong bubbler, a wimpy aquarium bubbler might not be enough for, like,reallygood results, but yes, I agree, spray equipment is overkill in most cases.Strong bubbler needs some considerations like using tank with high enough walls and some kind of lid, and some thought about managing the fumes, but it's way easier than a DIY spray system.I made our (a club) tank out of thick PVC sheets glued using PVC glue. There is a tight slit in the lid that holds the pcb. At the bottom, there's a bubbler that evenly distributes compressed air. It has been in heavy use for about 5 years now, with a HCl cupric chloride solution that has never been changed or even filtered, the tank hasn't even been cleaned. During that time, at least 1000 pcbs have been made. Some extra acid needs to be added about once or twice per year, or as the etch time gets too long. This is the easiest part of the process.We use negative dry film resist with a standard office laminator. This is the best thing since sliced bread.The most difficult, and frustrating part of the whole process is to use an overengineered technological piece of miracle called a "printer" to produce the masks, so that:(1) The printer prints anything at all,(2) it produces a dense (deep black) image,(3) and does it in correct size&shape.

author: tooki
author_rank: Super Contributor
timestamp: August 03, 2017, 09:08:18 am
content: Quote from: cdev on August 02, 2017, 08:14:12 pmSomeone mentioned here on eevblog that bubblers are a no-no with ferric chloride because the micro-spray that they create will then corrode everything in sight.P.S. Can you please,pleasestart using the forum's own quote tags instead of cobbling your own with HTML tags?

author: tautech
author_rank: Super Contributor
timestamp: August 03, 2017, 09:11:47 am
content: Quote from: Siwastaja on August 03, 2017, 08:24:24 amThis is the first thing you must get right and with toner transfer (the way I do it) the PCB package and the printer settings combined should enable you to get this perfect.My way:1. Print the PCB track layout to plain paper and mark which end of the paper exits the printer first (needed for #3).2. Check the scaling is correct.....lay components on the print or measure for correct sizing/scaling. Adjust PCB package and/or printer settings as necessary to get scaling correct.3. Stick your toner transfer medium over the printed image and print again.Two passes through the laser printer help control the shrinkage when the transfer takes place with subsequent passes through the laminator.Hard to get non-porous planes on only 600 dpi.

author: KL27x
author_rank: Super Contributor
timestamp: August 03, 2017, 09:42:42 am
content: QuoteI have thought with enough air, you could easily etch with pure foamed cupric chloride. I can easily overflow my tank with the bubbles/head. BTDT too many times on accident, trying to "maximize my settings." I figure if you wanted to do it this way, you could build a tank that opens up and get much wider at the top to prevent accidental overflow. Now you have a foaming etch tank with no moving parts.QuoteYup. Anywhere you have HCl in a container that is not gas tight, you get corrosive chlorine gas rusting nearby steel/iron. This is why I keep my tank outside. I wouldn't do any kind of ferric/cupric etching inside my home or office. Maybe large wearhouse or lab with good ventilation. In theory, pure ferric doesn't benefit from aeration. You just need the agitation. But in practice, ferric creates cupric chloride as it works. So aeration has practical benefit for ferric, too.It may be best for you to mix up ferric, use gentle flow/agitation for accurate etching, and then throw it out and start over when it gets too slow. Depends on your needs.

author: janoc
author_rank: Super Contributor
timestamp: August 03, 2017, 10:04:03 am
content: Quote from: CJay on August 02, 2017, 10:35:15 amPersulphate has the problem that it both doesn't work unless heated and decomposes rapidly. So unless you are making many boards every week, it is not a very economical option because you can't store it, it will go bad quickly (plus releases oxygen, so if you keep the bottle closed it could burst). It is a good etchant though.FeCl's only issue is that it stains everything and attacks anything metallic it gets in contact with. But as far as etchants go, it is still pretty tame - certainly beats anything using hydrochloric acid and/or peroxide.

author: janoc
author_rank: Super Contributor
timestamp: August 03, 2017, 10:15:06 am
content: Quote from: KL27x on August 03, 2017, 09:42:42 amThat's only true if you have added HCl to your ferric chloride (or bought liquid one with it added already). Moreover, it isnot chlorine! Chlorine is not very corrosive by itself unless the metal is hot - if it was, our water mains would have been failing left and right thanks to the chlorine that is being added to the water. What you are getting are bog standard HCl fumes, which are very corrosive, indeed. (just try to leave a bottle of the acid somewhere ...)If you have made your own etchant by dissolving FeCl3 crystals, then there is no reason for it to release any corrosive fumes (and it doesn't - I am keeping mine in the bathroom for years). If worried about sprays, just cover your etching tank or turn the bubbling down. It will etch just fine even with little to no bubbling too, it will just take a bit longer.

author: Fred27
author_rank: Unknown
timestamp: August 03, 2017, 10:43:21 am
content: Quote from: cdev on August 02, 2017, 08:14:12 pmI think spray etching it the best way to etch and the way it's done professionally. I've seen a few homemade spray etchers, but it seems a potentially messy business.

author: KL27x
author_rank: Super Contributor
timestamp: August 03, 2017, 11:19:47 pm
content: @janoc, yes you are right. This is why HCl and peroxide is the worst of the bunch for fumes. Cupric is impractical to use without occasionally running moderate excess of HCl. Else you will be futzing with the tank quite often. I have pair of scissors I leave next to my cupric, and it is well-covered in surface rust.Even freshly mixed solid ferric has some excess HCl in it, I suspect. In print etching, requiring very deep (accurate) etching, putting some sacrificial copper in a fresh batch of etchant is commonly done. Another method is to add small quantity of used etchant to the freshly mixed batch.In pcb making, the copper is very thin, and it is not uncommon to add a little excess HCl to the etchant to make it go faster and to extend the useful etching life. If running a mild excess, ethching accuracy goes down, but this is still way more accurate (in say 2 oz copper) than hcl and peroxide. I suppose this is a tradeoff and mixing up fresh ferric is more amenable to those doing this in enclosed spaces. (Well, mixing and bottling it outdoors, hopefully.)*I read paper, once. I don't remember what the units are, but measure of etching accuracy, ferric was 5/1. Cupric 4/1. And hydrogen peroxide and HCl is 1/1, IIRC. Running excess HCl reduces accuracy roughly in concordance with those figures, proportional to the ratio. Ammonium based etchants are actually most accurate, but I don't remember the number/rating.

author: janoc
author_rank: Super Contributor
timestamp: August 04, 2017, 04:26:20 pm
content: Quote from: KL27x on August 03, 2017, 11:19:47 pmAll you can have from the freshly dissolved solid ferric chloride is chlorine ions which could recombine with hydrogen ones from dissociated water molecules. However, that will not degas/fume, those will dissociate very quickly again. So there is no reason for it to corrode anything unless you spill it.If you add hydrochloric acid to the mixture, either because you want to regenerate the etchant or to produce cupric chloride and use that, then yes, it will degas and cause corrosion. I don't do it as I don't mind the few minutes of extra waiting time during the etching.Acid + peroxide combo is probably the worst possible - people love it because it is cheap (if you can get peroxide in larger than the tiny bottles used for cleaning wounds) and etches fast even without heating or stirring/bubbling. However that speed is also the reason for the inaccuracy you are describing because it is difficult to judge when to stop the process. A little too long and it undercuts already. And then there are the fumes and messy disposal of the spent etchant.

author: KL27x
author_rank: Super Contributor
timestamp: August 05, 2017, 07:29:27 am
content: QuoteI think people love it because it's fast and it is clear so they can watch the board etch. I have seen enough boards etch to want to stand there and stare.Also, it's clear, so it's environmentally friendly.QuoteI'm pretty sure most people say they can reuse it indefinitely by adding peroxide. Some do, and some probably say they "could" but just pour it in the lawn or down the toilet.QuoteThe speed has nothing to do with it. The speed is an aid, so you can stand there watching the etch and help along places that need it by repositioning the board or using a sponge. If I leave a 1 oz pour 12/12 board in my cupric tank for 2 hours, I'll have a fairly accurate 6/18 board with maybe 2 or 3 small breaks in traces due to localized surface effect/turbulence/flow. But the rest of the board will look remarkably similar to same board but designed from start with 6/18 traces. Even if you had perfect flow of HCl etchant with no "hot spots" you cannot achieve this. By the time you get the traces that thin, on average, you're gonna have very chewy wavy traces and a lot of breaks with large area of totally missing traces, because the etchant has tunneled so far that the resist has fallen off. It has to do with how the etchant works on a molecular level. I would surmise that the peroxide and HCl can work in much smaller space and has higher diffusion rate into these tight spots. Even though both etchants are mostly water, it's the larger ions that do the etching in ferric/cupric/ammonium etchants. What's a crawlspace to these etchants is a football field to HCl and peroxide. The thicker the copper, the more evident this is. I can do SSOP on 2 oz board with cupric. This is pushing the limits if I needed to make a lot of same board, but it is perfectly practical for smaller scale. This is pretty close to impossible with HCl and muriatic. In print making, they are etching 6 oz boards and even higher. They could not begin to do that with HCl.This board, for instance. If you said it was not that great, you'd be correct. It's absolutely horrible. But it's 2 oz pour. That's SSOP chip. Give this a try with HCl and peroxide. I made two of them, and they both are 100% functional, no jumpers needed. By naked eye it looks fairly ok. Under the microscope it's very evident it sucks, compared to 1 oz board. There is general waviness evident all around, and some very small spots where traces appear to be 75%. (There are two spots in the pic which looks like very thin areas, but this is just reflection of light. They are perfectly fine). But try this with HCl, you will more than likely end up with grossly visible defects and some post etch work to make the board functional. In this case, there's no reason for 2oz other than I had some 2/0 boards I wanted to use up, and this was an increasingly rare-fore-me single-sided pcb. With my toner transfer and etch setup, this is no big deal. "Repositioning board" is not necessary. It's just "come back later," and it will be all good.

author: janoc
author_rank: Super Contributor
timestamp: August 05, 2017, 09:25:18 am
content: Quote from: KL27x on August 05, 2017, 07:29:27 amI hope that was a joke, right? Since when is hydrochloric acid and copper compounds something "environmentally friendly"?Quote from: KL27x on August 05, 2017, 07:29:27 amUhhh, ecological aspects aside, if you keep doing this, you will have a very expensive and messy repair in your future once the pipe joints corrode and fail somewhere. The spent etchant contains a lot of hydrochloric acid that reliably attacks anything metallic and even some types of ceramic. Also your local waste water treatment plant is going to love you - pouring this stuff down the drain/toilet is not great for the bacteria they are using to treat the water.And pouring it in the lawn - you have got to be kidding, right?If you need to dispose of it and don't have a place that collects dangerous waste nearby, you need to neutralize it, e.g. using normal baking soda until it stops bubbling and fizzing (it will take a lot of that soda, that's normal). Then you can dispose of it relatively safely, at least it will not attack anything anymore.Quote from: KL27x on August 05, 2017, 07:29:27 amI will leave this to someone more competent in chemistry to comment on.

author: KL27x
author_rank: Super Contributor
timestamp: August 05, 2017, 09:44:11 am
content: I should have used my sarcasm button.As for undercutting, all you have to do is try etching a 4+ oz board with HCl and peroxide to see for yourself what happens. With ferric you will get it done, but it won't be pretty. With HCl and peroxide, you will have some resist floating in the tank by the time all the traces are done etching. And half the board will be missing. The toner is plastically/physically bonded to the copper. It's not that HCl is slippery and makes the toner fall off. It's eating away the copper that is holding the toner to the board. UV resist will fare no better.If you use HCl and peroxide, and you see some of the grossly overetched boards that I have made and are perfectly fine, you might raise an eyebrow. These don't happen with HCl. I have ruined perhaps one board beyond salvation in the last 4 years. I forgot it, overnight.

author: janoc
author_rank: Super Contributor
timestamp: August 05, 2017, 10:08:36 am
content: I am not using acid+peroxide, it is just not worth the trouble. I have used it once or twice in the past, it was a mess.Plus getting a peroxide here in any reasonable concentration and volume is not a trivial matter thanks to all that terrorism nonsense. Together with acetone it can be used to make TATP - an explosive of choice for homemade bombs, e.g. used in the London metro attacks and the recent airport attack in Brussels. I believe it is also used in some drug production process too. So sales of peroxide (or products containing it) in higher concentrations or larger volumes are fairly tightly controlled.And buying 10 tiny bottles of the medical 3% peroxide that is actually available is expensive. Worse, it doesn't work all that well in that concentration, it only dilutes the etchant (as it is mostly water).I am sticking to my ferric chloride, with no acid added (living in a rented apartment, can't have the crap corrode everything in sight here).

author: KL27x
author_rank: Super Contributor
timestamp: August 05, 2017, 10:16:32 am
content: I did a bit of armchair research a decade back on etchants and etch tanks. I dunno where it was I found it. There was a paper comparing all the common etchants in lateral etching speed/accuracy. Ammonium was the best, and ferric is slightly better than cupric. HCl is pretty bad, which is one of the reasons you do not want to have too high level of HCl in the cupric/ferric etchants.Things are perhaps more complicated. I'm not sure of the how or why. The paper didn't specify, so I speculate. But in my actual experience HCl is miserable when the copper is thicker than 1 oz.At least where the ammonium etchants are concerned, chemists perhaps know exactly why it has such low lateral etching:http://www.chemcut.net/wp-content/uploads/2015/03/alkaline_etch_process.pdfQuoteHow does the diamine monovalent copper complex know which wall is the sidewall?Maybe the "spent" particles just have natural affinity to fresh copper, and turbulence/flow tends to disturb the bottom of the trenches more than the sides?Another interesting factoid to me is how ammonium etchants work. IIUC, the NH3- allows Cu(II) to stay in solution despite high pH. So it etches with the same mechanism of CuCl2, but without the acidity. And the presence of NH3- and (potentially lack of H+) has effect in the higher etching accuracy of these etchants.Hmmm... perhaps the peroxide also plays a role by getting under the resist and decomposing into gas.

author: electrolust
author_rank: Unknown
timestamp: August 05, 2017, 03:50:42 pm
content: Quote from: Jay_Diddy_B on July 29, 2017, 12:17:41 amHow can you solder that without resist?!

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: August 05, 2017, 04:09:59 pm
content: Quote from: electrolust on August 05, 2017, 03:50:42 pmLike this:This is a similar board. It helps that the board is milled, there is a groove between the pads. I also use a lot paste flux, MG Chemicals 8341:http://www.mgchemicals.com/products/solder-and-accessories/fluxes/no-clean-flux-paste-8341Although it is no clean flux, I always clean with IPA.After milling the board is tinned with MG Chemicals 421 Liquid Tin.Regards,Jay_Diddy_B

author: janoc
author_rank: Super Contributor
timestamp: August 05, 2017, 07:28:25 pm
content: Quote from: electrolust on August 05, 2017, 03:50:42 pmI have done even SC70 packages (some DC-DC converters and LED drivers come in these) on such homemade board with no soldermask (but etched, not milled). No big deal with a little care. Many commercial boards don't have soldermask between the pins neither.Use a lot of flux, preferably the gel type because the normal liquid one evaporates right away - not good, especially if you need to use hot air. Flux makes the solder flow better and the solder's surface tension will prevent it from forming bridges. (conversely, if you want to make a bridge on a veroboard *do not* add flux). A magnifier helps for inspecting the work.It isn't a production quality board, but these home-etched boards are pretty much all one-offs, prototypes and such, so if it looks a bit messy it is not a big deal.

author: CJay
author_rank: Super Contributor
timestamp: December 01, 2017, 09:52:16 am
content: So I finally have time to get back to the PCB milling and experiment, I think I know what was wrong, a combination of a bad bit (too much flex) and feed rate.With that in mind I'm going to order some new carbide bits, I think these:http://www.axminster.co.uk/proxxon-tungsten-carbide-milling-drills-ax804131and have another go.I'm hopeful I will be able to get better results as those bits look more 'sturdy' than the ones that I was recommended to use by the people at the FabLab

author: cdev
author_rank: Super Contributor
timestamp: December 01, 2017, 04:43:32 pm
content: I use plain cider vinegar, corner drug store hydrogen peroxide and table salt (regular table salt works great) Granted, all of the boards I have made are tiny, the largest was maybe 5 x 10 cm but its very easy, only takes a few minutes, and the detail you get is as good as with any other process. Not a lot of peroxide is used. It doesn't have to be strong. It's just ridiculously easy. Also, I have never stained anything and never poured anything into the sewers, I just pour the liquid left at the end into a large plastic juice bottle and let it evaporate. The fumes are not strong and simply having a window open and our regular household ventilation running is enough to make it a non-issue.A web site did a survey to see which methods could etch PCBs with the most detail. I don't think the hydrogen peroxide/salt/vinegar method creates any less detail than the others.https://hackaday.com/2014/05/08/testing-the-efficiency-of-pcb-etchants/http://www.instructables.com/id/Is-the-best-PCB-etchant-in-every-kitchen-/?ALLSTEPSQuote from: janoc on August 05, 2017, 10:08:36 am

author: brainwash
author_rank: Frequent Contributor
timestamp: December 01, 2017, 07:39:43 pm
content: Note that peroxide for wounds is a big no-no. It prevents proper healing and regeneration as it kills all the cells, including the reconstruction ones. Not related to the topic, but useful information.

author: tooki
author_rank: Super Contributor
timestamp: December 02, 2017, 07:41:20 pm
content: Quote from: brainwash on December 01, 2017, 07:39:43 pmIt’s good for disinfecting a fresh wound (not for deep wounds!!), and for stopping bleeding. But no, after the initial rinse, should not be used. It’s great for removing blood stains though!

author: brainwash
author_rank: Frequent Contributor
timestamp: December 03, 2017, 01:07:44 am
content: For me H2O2 has some very narrow use-cases. Removing ear wax, cleaning probing needles, in the future some retro-bright and perhaps exposing PCBs. For everything else I use isopropyl and acetone. For wounds I use a 20% isopropyl dilution. It has a clear constitution, which throws all people with medical training off, expecting to see a bluish solution. But it does work even better than off-the-shelf and does not cause skin flaking (as H2O2 does).I'm not saying it's better, just that it worked better for me and all the people I had to treat at my house. I also feel safer using 70-99.9% isopropyl in my household ultrasonic cleaner than acetone, since it needs to be heated to 50-70C for improved efficiency. Just trying to say that isopropyl alcohol seems a good product to have around the house.I do have other solvents and acids and treat those with utmost respect. For example 99% tricloracetic is so nasty I document everything I do with it, at home. By comparison, hydrochloric and iso- are much tamer.For reference, I grew up in a household that had fresh samples of fumic (>99.9%) acids, from sulfuric to nitric and acetic. Never had any serious burn, but it was only a matter of luck. I guess I'm trying to say that all concentrated (>>10%) chemical products should be treated with care. But with the right dilution, they can do a lot of stuff that off-the-shelf stuff can't. Unfortunately this is rarely documented, as no one wants to assume responsibility.

author: cdev
author_rank: Super Contributor
timestamp: December 03, 2017, 02:07:48 am
content: a solution of n-acetylcysteine in water decimates biofilms and may be useful for some kinds of disinfection.

author: jmelson
author_rank: Super Contributor
timestamp: December 03, 2017, 04:21:35 am
content: Quote from: Siwastaja on August 03, 2017, 08:24:24 amI have a cast-off Kepro spray etcher, and use FeCl. When I have the dry film resist properly exposed and developed, and the etchant heated up to the right temperature, 1 Oz Cu boards etch completely in about 3 minutes. If it takes too much longer than that, then the etching starts cutting under the resist and the traces get narrower than designed.Jon

author: saike
author_rank: Regular Contributor
timestamp: December 03, 2017, 07:34:30 am
content: I do a lot of this pcb milling as part of my job. The cutting bits are obviously a vitally important part of successfully producing a board. I have used $20+ bits that have produced mediocre results at best and <$1 Ebay bits that are brilliant.I would suggest you try something like thesehttps://www.ebay.co.uk/itm/10pcs-20-Degree-0-2mm-3-175mm-Steel-CNC-Router-Tool-Carbide-PCB-Engraving-Bits/152069708221?epid=1294557023&hash=item23680f99bd:g:VE4AAOSwtGlZGmcuI have no connection with these people I just use these bits a lot.20 degree 0.2mm is a good compromise between cut width and tip durability. Start with the absolute minimum depth of cut and increase by 0.01mm until complete copper clearance is achieved. Don't give up, once you get results you will never go back to faffing around with etchants and hand drilling again. (Okay that is tongue in cheek, I know a few people will be frothing at the mouth now)

author: janekm
author_rank: Unknown
timestamp: December 03, 2017, 10:25:00 am
content: Quote from: rstofer on July 28, 2017, 08:34:44 pmI imagine they don't want people cutting fibreglass and inhale the particles. I've seen others struggle with milling PCBs in similar Roland machines... they really don't seem to be much better at that. My $100 kit engraver does much better

author: tooki
author_rank: Super Contributor
timestamp: December 03, 2017, 04:16:35 pm
content: Quote from: brainwash on December 03, 2017, 01:07:44 amYou mean people who only think of Sterilium? Cuz in the Americas, clear isopropyl disinfectants are common, and medical professionals most certainly do not expect it to be blue. FYI, 70% IPA is ideal for skin disinfection (e.g. before injection), being more effective than higher concentrations. I’m not sure what concentration is ideal for wounds.