Good morning Leela. ( VU3LGX ). And, Good morning, to rest of all YL's and Old men.
On 23/11/2007 you mailed in groups and wanted to know about PCB design-basics. Sorry for be-lated reapply, as because I only came to know about that Mail yesterday as I was in the process of deleting my old mails. I am not a master of PCB design, but what-ever I know and do it in my home I'll try to make you understand. Making Homebrew PC B's is not at all a costly of unconventional affair, if you follow these simple techniques. Most of the homebrew haves PCB invalidity of printed Circuit board, major problem! Normally the PCB manufacturing process involves use of expensive equipment including a large vertical camera, dark room equipment and accessories, stencil screen and Ultra-Violet light lamps. However, fabricating your very own single/double side PCB's will cost a only a few ohms of impedance. Follow this technique described here and the materials left could be used for another projects. For home brewing PCB's you require (1) A Computer (2) 600-1200 dp laser printer with treasing paper (3) Photoshop or Auto-cad Software for designing & exact sz However we can also use another software special PCB design software.(Demo versions of various PCB designing software packages are frequently included with Electronics Magazines or you may also download from Net. (4) Miscellaneous items such as single/double side copper- laminated board. W-D 40, toothbrush, hacksaw, marker-pen, a small bucket or mug, gloves, and not to forgot a hand drill. Etching is one of the major steps in the chemical processing of the subtractive of PCB designing. By this process, the final copper pattern is achieved by selective removal of all the unwanted copper to retain the desired circuit patterns. Several chemicals are used for etching. The most common etchants are. 1) Ferric chloride; 2) Ammonium persulphate; 3) Chromic acid; 4) Cupric chloride; and 5) Alkaline ammonia. Ferric chloride is the oldest and perhaps the most common etchant. It is widely used in the 'printing' and 'etching' process in the PCB industry. It has high etching rate and is cheap & easily available. However one can also use cupric chloride. It compares well with ferric chloride, with the advantage that it does not sludge as ferric chloride, does. It is used in the production of fine line multi-layer PCB`s Here solder masking & Screen-printing is extended to make the process easier. First design (or pre-designed layout) is to be printed from a lazier-printer in maximum dpi on a teasing paper (for screen printing), or (photo glossy paper if u using my process)any of the net cafe will do it for u @ as low as Rs. 20/- (Please don't forget to mirror or flipped let + to right. Which would transfer a sharp, black print (toner transfer) onto the copper laminate. (You can also use varo-boards to explimenete this process, but my friend high frequencies TX circuit do need a all side ground). First, scrub the copper side of the copper-clad laminate used for the PCB board with a sponge, remove oxidation, stains, etc, so that the copper laminate surface of the PCB become uniform and shiny. Place and align the paper (with the toner side down) on the copper side, using an electric cloth iron heated to the maximum setting. on the back of the paper. Pressing firmly, heat the entire pattern for at least half a minute. Now you have to remove the paper from the PCB again. This can be done easily by putting the PCB (with paper) into hot water. Now when the toner is transferred make necessary correction using a Sharpe or other etch-resistant black-ink marker pen. Etch the unwanted copper from the board using the ferric chloride solution. Ferric chloride is actually a salt, not an acid. Use the powder form of it instead the lump one. Dilute the powder in water. In which you will have to immerge the board. Immersion etching is the semi-plast technique which requires only a tank containing etching solution into which the boards are immersed. When etching solution is used for a much longer time, the etchant becomes weak. You can add a common chemical to ferric chloride to rejuvenate it. Hydrochloride acid may be used but I used "muratic acid" HE He Haeeeeeee!! Now finally it is ready, You can drill the holes, but it is always better to drill them before etching. I do surface-mount HE He Haeeeeeee!! You can also do silver-plating; electroplating using the catalyst potassium argentocyanide and 12 volts, but that is another topic. HE He Haeeeeeee!! You may also buy good book like 'PRINTED CIRCUIT BOARDS. Design, Fabrication, Assembly and Testing. By Dr RS Khandpur. Tata McGraw-Hill Publication. for better idea. Very soon, I am also going to put some picture graphics of the systematic in my Home-page http://www.sandeeplohia.4t.com/index_2.html which is under construction. If you spot something not right or errors in typing, please do not hesitate to call upon me and let me know. Should you happen to spot something that looks 'not quite right' or something that I might have not explained in more detail...do drop me a line and I will get back with you on it. Please do not hesitate to send me a letter. I am here to help in any way that I can... I might have not explained in more detail...do call me on my lima-lima 9432315805 E-Mail address = [EMAIL PROTECTED] I will gladly help you through this... to shed more light on your quarry, Along with other knowledgeable visitors, I will get back with you on it. and more than happy to help! I would also like to know if there is any technology which can make the PCB water-proof by means of laminating it from any latex resin or polymer? Please reapply me if any body knows about it ......your's friend, Sandeep Lohia ( VU3SXT) 73's
