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Several of you have written of the benefits and good quality that can be had by using the photoresist copper clad boards. You now have my interest. I have some of the raw materials to attempt this method including pre- sensitized copper clad, and developer. I even have glass plates to keep the transparancy in close contact with the copper. I do not have a UV light source. I didn't buy one as I didn't want to spend the money. Some of you have told me that you made a light box. What types of lights/lamps work for exposure? I saw somewhere that a blacklight works. Is this true? Our old Diazo machine at work seems to have a long flourescent "black" light that it uses to expose diazo paper. (BLUELINE MACHINE). How would I construct a lightbox for exposure? Most if not all my PCB's are small. Thje biggest board that I have etched was 5x7, so I don't need a giant box. I don't need any help with making transparancies as I have access to a photoplotter (typesetting machine that directly exposes film). There are no issues with film growth as there is no heat in the process. There are no issues with pinholes/banding as this is a professional imager used to expose printing plates for magazine reproduction. All I must do is output 1-to-1 EPS file and the imager does the rest. So please, if you could help me build a UV light source to expose small PCB's, I would appreciate it. Thanks

Hi Steve and the group, Most of the dry film photo resist used for printed circuits requires lamps to have the peak spectral output at 365 nanometers. They will respond to other wavelengths but more power will be required. A quartz lamp will probably work because many years ago we accidently exposed some dry film with stray light from a quartz tube. The way to test this is to laminate some copper panels with photo resist and use a Stouffer 21 step wedge. This step wedge is nothing more than a calibrated piece of film that starts out clear and progresses to opaque black in 21 steps. I think we ran our exposure to retain a step 8 during development. This is probably an overkill for homebrew circuits but some may want to try this out because it will give you the absolute final word on exposure performance. These test strips are very inexpensive. The old fashion trial and error method will also work. More info is located here. http://www.stouffer.net/Using21step.htm Best results will be obtained by using a higher power lamp and INCREASE the distance from the lamp to the board being exposed. This allows the light beam to become collimated or "staightened" out. If you have ever had undercutting problems try this out as it may help. If anyone want to try out the quartz type of lamp start out at least 12" or more from the board being exposed and adjust the time to get the correct exposure. It may take several minutes but I think it should work. We never used these in a commercial setting because exposure speed for production was important. I wouldn't worry about this for hobby circuits... whats a few extra minutes if it works? BTW, these quartz lamps were used for years in machines that would melt solder plated boards and fuse the solder to the underlying copper. Don't get too close to your film when using this type of lamp! Don't worry about glass types because the commercial exposure units use regular window glass for the exposure tray with a mylar plastic sheet over the top. The board is between these layers and a vacuum pump removes the air for a very tight contact with the top and bottom films. This tray slides into the exposure box for the proper amount of time and then rolls back out automatically. The vacuum is released, board removed and the process starts over. A hobby version of this machine could be built at a very low cost. I have thought about making these myself and selling them. Quartz glass is the proper type to pass UV light but it just isn't required. The photo resist we used was DuPont 4715 which is their 4700 series and 1.5 mils thick. Here is a web site that might be of interest. http://www.dupont.com/pcm/techinfo/general/index.html I hope this info helps. Tom

I'm new here but find this list very interesting. A good UV lighting system is the plain old mercury vapor lamps. These are commonly used for dusk-to-dawn lighting. The bulbs are available in several wattages such as 175, 400 and 1000 watts. One of these bulbs and a reflector makes a great UV exposure system. Visit any large warehouse and check out the lighting system since these are very commonly used in larger buildings. I have a commercial exposure system that uses this type of bulb. It is a Colight Model DMVL-930 with 1000 watt bulbs on the top and bottom. The exposure time when using 1.5 mil dry film photoresist is 17 seconds. If there is any interest in this I can photograph the "guts" of this machine next time I clean the reflectors and post the photographs in the photo section of this list. It really would not be hard to make this exposure unit. Polished aluminum sheeting or aluminmum foil could be used to make the reflector system. I have helped several of my ham buddys set this type of unit up and they have all been amazed at how fast this can expose the photo resist. You can also make silk screens with this setup. I made my first hobby circuit board in 1966 and owned a commercial printed circuit business for 23 years. We closed that plant last year due to foreign competition and rising costs. I did keep the best "small" equipment for my own home shop. This still allows me to make boards for the instruments I make as well as my ham radio projects. We gave away the plating operation because it was really a drag putting up with the evironmental issues etc. I kept one smaller photoplotter, several semi-automatic drilling machines, silk screening equipment and all of the tooling and setup stuff. The big Excellon CNC drilling and routing equipment was all sold off. I started my company on the kitchen table in the late 1970's and it looks like I've gone full circle but this time ended up in the basement! It's much more fun this way I might add. We made boards up to ten layers back then but it was just way to much work and the headaches just kept getting worse. Too much work, too many hours, too little pay and no more fun !! I do enjoy the hobby side of this technology and would be willing to help out with ideas and maybe some equipment projects that could be posted on this list. If there is any interest let me know. Sorry about the long post... sometimes I get going and don't know when to stop!!! Hope I can help out. Tom

A friend of mine long ago claimed he used a week solution of nitric acid for etching PCBs. Has anyone here tried this? I'm thinking I need an exhaust hood in my basement. I figured if I use a fan then I have to worry about the fan being eaten by acid fumes, so thought maybe I'd use my air compressor with a simple homemade venturi pump made out of plastic pipe. Whatdya think? Steve Greenfield __________________________________________________ Do You Yahoo!? Yahoo! Tax Center - online filing with TurboTax http://taxes.yahoo.com/

If you are looking to go to a film there is a very nice product sold by M&R Marking. It is a negative film system that has extremely easy to use water based chemistry. To produce a film you print a positive image using a standard printer (I have always done it on a laser, but an inkjet would likely work). You then do a contact print using standard black light bulbs onto the negative film. Now to develop it you just spray on a water based fluid from a squirt bottle and wait 90 seconds then rinse and scrub the film under cool water with a paper towel. The result is a completely negative film that is as opaque as the films I have had done by a commercial photo plotter. Product info at: http://www.mrmarking.com/phnegs.html Tim [Denver ,CO] > While it plots to film, I think you can get a few ideas from > it. And there are advantages if you can generate a good > film, such as exposing as many boards as you want from it.

Hi, Nobody liked my light on a plotter idea. I was told the light source would have to move too slow. The board would take way to long. Ok, I use Mechanical Etching bits myself. But what if you coated the whole board with resist. Then you put a sharp point in the plotter. Have the plotter do isolation paths. Then the board goes to the acid. John

Skateboard bearings! http://www.roboshack.com/index.html Steve Greenfield __________________________________________________ Do You Yahoo!? Yahoo! Tax Center - online filing with TurboTax http://taxes.yahoo.com/

http://www.radixgmbh.de/ Doesn't that price translate to approximately $800 USD? Anyone here read German? Steve __________________________________________________ Do You Yahoo!? Yahoo! Tax Center - online filing with TurboTax http://taxes.yahoo.com/

Hi everyone. Just found this group and I have been skimming through the posts. I'm interested in building a CNC PCB mill/drill. Stepper motors, linear bearings/rods, antibacklash nuts on Acme rod... and a Black and Decker RTX. The resolution works out to 0.0005" per full step and 0.00025" if I half step. Is 1/2 or 1/4 of a thousands a good resolution for this project? Does anyone have links to similar projects? Hints? Tips? Insight? Thanks mike

Hi All. I uploaded a picture of a milled PCBoard to the photo area. The board was milled using a Dremel tool and a homemade milling machine. Milling speed 6" per minute at 16,000 RPMs. That is how the boards looks before it is deburred. Notice the pre drilled holes done during milling. The board gets deburred using a steel bristle brush the size of a tooth brush. That board is a Piker 4X controller board. If you have any questions please ask them here. John

Hi All, Just a quick note! With the Think and Tinker Bits you can get .0004" to .0006" of feedrate for every revolution of your spindle motor. So if you have a machine that has a top speed of 10,000 rpms you can only use a 6" feedrate. That is pushing the tool hard. A 5" per minute rate would result in longer tool life. Very simple PCBoards 2" by 2" work well no matter what you do. Problems show up on boards 4" X 6" or larger with 200 inches or more of traces. I was told by someone he was using a cheap air powered grinder to make circuit boards. With 50,000 rpm he claimed a speed of 20" per minute. A few weeks later he contacted me when he tried milling a real pcboard. Power supply circuits are a snap! The problems show up when making boards that have small ICs. John

ok, so I've read everything I can on smt soldering, got my Radio Shack desoldering system to convert to a hot air pencil, bought the Kester solder paste syringe.... A few basic questions. People say to buy the "good quality" desoldering braid. What brands/model have people used with good success? I went to "soldersonline.com" and they have a plethora or braids to choose from. Three brands - Plato, Wick, Tech Spray. The've got fluxed, no- flux, no-clean, anti-static and different colors and gauge. What to get for general use?? I already bought my Kester Solder paste syringe, but DigiKey doesn't sell the needles. What spec should I get in a needle? DigiKey does sell an .050" needle used for flux dispensers. Can I use this with the Kester syringe? I'm guessing that there are just a few standard syringe tip size and a bunch of needle sizes. Also, why is the Kester Solder Paste so much ($42) while the other brands of "no clean" solder paste at "soldersonline.com" is $10. are these pastes acceptable for this use or is there some reason why they're no good? About flux. Water soluable flux pen? or just a vat of flux that I brush on? Or a syringe? Pen and vats are cheap. Syringe is expensive. Any suggestions on these items would be greatly appreciated. Specifics will be especially useful. Thanks, Ted

Here are some drilling machine ideas. I have a small high speed drill press that works great with carbide drill bits. For simple low volume jobs this drill press can't be beat. I think it works much better than the Dremel tool types. This drill press was on sale recently at KBC Tools for $130. For the more complex jobs I like to use a stylus operated drilling system. The machine I use is made by Nawide Machine Tools. It has an optical scope for making the master template or for drilling smaller quantities. The scope screen has 15 power magnification and a clamping system. You line up the pad in the optical screen and push the foot switch. The machine pressure foot clamps the stack of boards or template, drills the hole from a bottom mounted spindle, retracts the drill bit and releases the pressure foot. It is very quick and every bit as accurate as the best CNC machine. If you make a template and attach the stylus assembly you can drill 60-80 holes per minute with precise placement. We usually stack the panels three deep and sometimes four deep depending on the smallest drill size when using this machine. Here is the best part. These machines can be purchased for next to nothing. The last machine I bought was only $200 and had the optical scope and stylus assembly. It is a 1986 vintage Aetna Acrodrill in perfect condition. The commercial shops have very little use for these machines and will almost give them away. Another machine to look for is any of the Excellon Quad Drills. These machines had a stylus assembly on a very smooth manual XY movement with four high speed spindles. This machine can be made into a CNC version by just adding the XY leadscrews and computer. These nmachines are smaller than an office desk and have built in casters for easy moving. Excellon even made a version of this called a Quadramatic 1255 and Quadramatic 1231. The 1255 accepted 12" x 18" panels and the 1231 took 10" x 12" panels. The XY movement is driven by ball screws. I can assure all of you that these machines are excellent for hobby AND professional drilling. Take off the old General Electric NC control system and interface with your own PC CNC control system. Very little mechanical work would be needed and you would really have something to show off. I have personally turned down offers to haul these away for free. They are not that big or heavy and will fit in any pickup truck. Most of these systems have already hit the dump or scrap yard but if you can find one you will not be sorry. I have owned very large and expensive Excellon drilling and routing machines in the past and the only thing they had over the methods discussed above was speed and expense. My favorite drill was the Excellon EX-200 Driller/Router with CNC-6 controller but even this expensive machine was only averaging about 125 holes per minute. I can drill the ten boards I need each week in less than 20 minutes with a stylus drill. This includes setup time on a 4" x 6" board with 300 holes. Save some money and try out some of these ideas. You will be amazed with the results. Tom

Here are some drilling machine ideas. I have a small high speed drill press that works great with carbide drill bits. For simple low volume jobs this drill press can't be beat. I think it works much better than the Dremel tool types. This drill press was on sale recently at KBC Tools for $130. For the more complex jobs I like to use a stylus operated drilling system. The machine I use is made by Nawide Machine Tools. It has an optical scope for making the master template or for drilling smaller quantities. The scope screen has 15 power magnification and a clamping system. You line up the pad in the optical screen and push the foot switch. The machine pressure foot clamps the stack of boards or template, drills the hole from a bottom mounted spindle, retracts the drill bit and releases the pressure foot. It is very quick and every bit as accurate as the best CNC machine. If you make a template and attach the stylus assembly you can drill 60-80 holes per minute with precise placement. We usually stack the panels three deep and sometimes four deep depending on the smallest drill size when using this machine. Here is the best part. These machines can be purchased for next to nothing. The last machine I bought was only $200 and had the optical scope and stylus assembly. It is a 1986 vintage Aetna Acrodrill in perfect condition. The commercial shops have very little use for these machines and will almost give them away. Another machine to look for is any of the Excellon Quad Drills. These machines had a stylus assembly on a very smooth manual XY movement with four high speed spindles. This machine can be made into a CNC version by just adding the XY leadscrews and computer. These nmachines are smaller than an office desk and have built in casters for easy moving. Excellon even made a version of this called a Quadramatic 1255 and Quadramatic 1231. The 1255 accepted 12" x 18" panels and the 1231 took 10" x 12" panels. The XY movement is driven by ball screws. I can assure all of you that these machines are excellent for hobby AND professional drilling. Take off the old General Electric NC control system and interface with your own PC CNC control system. Very little mechanical work would be needed and you would really have something to show off. I have personally turned down offers to haul these away for free. They are not that big or heavy and will fit in any pickup truck. Most of these systems have already hit the dump or scrap yard but if you can find one you will not be sorry. I have owned very large and expensive Excellon drilling and routing machines in the past and the only thing they had over the methods discussed above was speed and expense. My favorite drill was the Excellon EX-200 Driller/Router with CNC-6 controller but even this expensive machine was only averaging about 125 holes per minute. I can drill the ten boards I need each week in less than 20 minutes with a stylus drill. This includes setup time on a 4" x 6" board with 300 holes. Save some money and try out some of these ideas. You will be amazed with the results. Tom

Here are some drilling machine ideas. I have a small high speed drill press that works great with carbide drill bits. For simple low volume jobs this drill press can't be beat. I think it works much better than the Dremel tool types. This drill press was on sale recently at KBC Tools for $130. For the more complex jobs I like to use a stylus operated drilling system. The machine I use is made by Nawide Machine Tools. It has an optical scope for making the master template or for drilling smaller quantities. The scope screen has 15 power magnification and a clamping system. You line up the pad in the optical screen and push the foot switch. The machine pressure foot clamps the stack of boards or template, drills the hole from a bottom mounted spindle, retracts the drill bit and releases the pressure foot. It is very quick and every bit as accurate as the best CNC machine. If you make a template and attach the stylus assembly you can drill 60-80 holes per minute with precise placement. We usually stack the panels three deep and sometimes four deep depending on the smallest drill size when using this machine. Here is the best part. These machines can be purchased for next to nothing. The last machine I bought was only $200 and had the optical scope and stylus assembly. It is a 1986 vintage Aetna Acrodrill in perfect condition. The commercial shops have very little use for these machines and will almost give them away. Another machine to look for is any of the Excellon Quad Drills. These machines had a stylus assembly on a very smooth manual XY movement with four high speed spindles. This machine can be made into a CNC version by just adding the XY leadscrews and computer. These nmachines are smaller than an office desk and have built in casters for easy moving. Excellon even made a version of this called a Quadramatic 1255 and Quadramatic 1231. The 1255 accepted 12" x 18" panels and the 1231 took 10" x 12" panels. The XY movement is driven by ball screws. I can assure all of you that these machines are excellent for hobby AND professional drilling. Take off the old General Electric NC control system and interface with your own PC CNC control system. Very little mechanical work would be needed and you would really have something to show off. I have personally turned down offers to haul these away for free. They are not that big or heavy and will fit in any pickup truck. Most of these systems have already hit the dump or scrap yard but if you can find one you will not be sorry. I have owned very large and expensive Excellon drilling and routing machines in the past and the only thing they had over the methods discussed above was speed and expense. My favorite drill was the Excellon EX-200 Driller/Router with CNC-6 controller but even this expensive machine was only averaging about 125 holes per minute. I can drill the ten boards I need each week in less than 20 minutes with a stylus drill. This includes setup time on a 4" x 6" board with 300 holes. Save some money and try out some of these ideas. You will be amazed with the results. Tom

Here are some drilling machine ideas. I have a small high speed drill press that works great with carbide drill bits. For simple low volume jobs this drill press can't be beat. I think it works much better than the Dremel tool types. This drill press was on sale recently at KBC Tools for $130. For the more complex jobs I like to use a stylus operated drilling system. The machine I use is made by Nawide Machine Tools. It has an optical scope for making the master template or for drilling smaller quantities. The scope screen has 15 power magnification and a clamping system. You line up the pad in the optical screen and push the foot switch. The machine pressure foot clamps the stack of boards or template, drills the hole from a bottom mounted spindle, retracts the drill bit and releases the pressure foot. It is very quick and every bit as accurate as the best CNC machine. If you make a template and attach the stylus assembly you can drill 60-80 holes per minute with precise placement. We usually stack the panels three deep and sometimes four deep depending on the smallest drill size when using this machine. Here is the best part. These machines can be purchased for next to nothing. The last machine I bought was only $200 and had the optical scope and stylus assembly. It is a 1986 vintage Aetna Acrodrill in perfect condition. The commercial shops have very little use for these machines and will almost give them away. Another machine to look for is any of the Excellon Quad Drills. These machines had a stylus assembly on a very smooth manual XY movement with four high speed spindles. This machine can be made into a CNC version by just adding the XY leadscrews and computer. These nmachines are smaller than an office desk and have built in casters for easy moving. Excellon even made a version of this called a Quadramatic 1255 and Quadramatic 1231. The 1255 accepted 12" x 18" panels and the 1231 took 10" x 12" panels. The XY movement is driven by ball screws. I can assure all of you that these machines are excellent for hobby AND professional drilling. Take off the old General Electric NC control system and interface with your own PC CNC control system. Very little mechanical work would be needed and you would really have something to show off. I have personally turned down offers to haul these away for free. They are not that big or heavy and will fit in any pickup truck. Most of these systems have already hit the dump or scrap yard but if you can find one you will not be sorry. I have owned very large and expensive Excellon drilling and routing machines in the past and the only thing they had over the methods discussed above was speed and expense. My favorite drill was the Excellon EX-200 Driller/Router with CNC-6 controller but even this expensive machine was only averaging about 125 holes per minute. I can drill the ten boards I need each week in less than 20 minutes with a stylus drill. This includes setup time on a 4" x 6" board with 300 holes. Save some money and try out some of these ideas. You will be amazed with the results. Tom

How 'bout this little thing? Too much weight to put in a plotter, but maybe in a homebuilt router/engraver. http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=43155 58,000rpm no load. There is a Harbor Freight Tools about 1/2 mile from my house. How are you guys measuring runout? Drill with a stiff bit then measure the size of the hole? I don't have a micrometer that can measure the inside of a round hole. Steve Greenfield __________________________________________________ Do You Yahoo!? Yahoo! Tax Center - online filing with TurboTax http://taxes.yahoo.com/

I'm not trimming my reply because I am forwarding this to the Homebrew_PCBs list. Wow! Nice videos. The hot air method looked pretty fast to me, and if you angle the head so it is blowing straight down or even slightly away from the chip I don't see how you are really heating it up any more than the other methods. I've only done the one pin at a time method myself. They all look like they work very well. I'd worry about solder bridges created by the continuous flow solder painting method. Steve Greenfield --- tedinoue <ted@...> wrote: __________________________________________________ Do You Yahoo!? Yahoo! Tax Center - online filing with TurboTax http://taxes.yahoo.com/

I'm curious why there is so much interest in hobbyists who make no more than couple of PCBs per week would need a CNC drilling machine to drill the holes. I found hand drilling is not that big a deal when you have a good drill press. There is a prototype place near my area and I noticed they hand drill the holes even though they have a small CNC drilling machine. The owner of the shop told me by time they setup the machine its quicker to hand drill. So, anyone thought about building a really good drill press ? The drill press I made couple of years ago is still working very well and I'm happy with it. The basic design uses a straight grinder mounted to the end of a long arm (400mm) which pivots at the opposite end. This is mounted on a wooden base. ___ | | o__________|_| straight grinder | | _|____________________ wooden base (18 mm MDF) The arm is made from a piece of 50 x 50 mm aluminum square. The pivot is made from two thrust bearings (from car clutch) that clamp on opposite sides of the square aluminum arm. This is then fixed to the wooden base with two pieces of aluminum right angles. In the diagram, thrust bearings are "2", the arm is "3". Threaded bar, "4", goes through the right angles , the thrust bearings and square arm so everything is tightly clamped. _ ____ _ | || | | || | 4=== | |2 | 3 | 2| | ===4 | || |____| || | |----- | | -----| ----------------------------------- ----------------------------------- <-- wooden base This setup gives stable and extremely smooth vertical movement of the drill. There is of course an inherent arc movement of the drill bit. This does not cause a problem when the drilling depth is only a few millimeters. The most difficult part for me was mounting the straight grinder to the end of the arm. This fixture needs to be adjustable to allow slight alignment of the drill so it has perfect vertical feed. I choose a straight grinder (BOSCH GGS27) because it was the only thing around that came with a precision hardened steel ground collet and also in my price range. The roundout is acceptable for carbide bits, (haven't broken my 0.45 mm bit yet). The Dremel I first tried was useless because of the sever round out. Luckily I got my money back. Major problem with this machine is it can take up a bit of space. It compromises low complexity for size. One improvement to the design would be to add a stepper motor control for the down feed. That way both hands can be used to position the PCB and a food pedal to operate the drill feed. Any thoughts ?

Hi All, Somebody asked me about traces that run between pads. This I feel is one of pitfalls of milling PCBs. See the photo in the KLEINBAUER folder. My new board only has 12 traces that go between pads. I now have a few options. 1 Don't mill boards so deep. 2. Make pads smaller and drill with a different bit. As you can see in the photo, the traces are there! I can use the board for test purposes. But unless I can get the trace wider, I can't sell the board. I mill the boards deeper so they are easier to solder. John