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'''Homebrew PCB fabrication''' with the emphasis on quickly and efficiently producing consistently high quality
[[Printed circuit board|
== PCB layout ==
{{
== Warnings ==
Dust and fumes ...
===Best Practices===-->
== Cutting PCB to size ==
With SRBP use a craft knife and straight edge. Score it deeply on both sides. Clamp one or both sides between wood to prevent the board being scratched. Then snap it off. A craft knife works especially well for perforated prototyping board. Score down the center of a row of holes, line the score line up with the edge of the table, and press down quickly on the overhanging piece.<ref name="eese">[http://electronics.stackexchange.com/questions/1151/how-do-you-cut-pcb How do you cut PCB?], Electrical Engineering Stack Exchange</ref>
FR4 boards are much harder to cut and very hard on tools.<ref name="diyaudio">[http://www.diyaudio.com/forums/parts/62929-easiest-way-cut-pcbs.html Easiest way to cut PCB's], diyAudio forum, August 2005</ref> A PCB guillotine is the right tool for the job. Failing that use a bench shear or an office guillotine that can cut through more than
Alternately take a straight edge and secure it along the line to cut. Then take a chisel (one set aside for this), and run one of the corners along the straight edge. First pass go lightly to just get a bit of a groove dug in for the tool to follow so it wont jump out on subsequent passes. Next pass or two press hard, and dig in for a deep groove. Score on both sides. Secure the board and snap the piece off. To finish the edge make a pass or two along it with a fine file.<ref>[http://www.eevblog.com/forum/manufacture/cutting-fr4-boards/15/ Cutting FR4 boards], EEVblog forum, August 2012</ref><ref name="diyaudio" />
== Masking ==
There are two popular methods of masking the copper laminate from the etchant, the toner transfer method is cheap and simpler but takes a lot of patience and fiddling about. The more expensive photo resist method can be much more accurate and one printout can be used multiple times but also requires an [[UV exposure box]] and developing the board.<ref>[http://www.diystompboxes.com/smfforum/index.php?topic=102924.msg914631#msg914631 Re: DIY etching PCB's
=== Toner transfer ===
{{Main
Using a laser printer or copier, this does not work with an inkjet printer, to print an image of the PCB tracks on glossy paper. Laying this printed side onto the de-oxidised and de-greased copper laminate and using an iron at a high temperature, on the rear of the paper to transfer the toner from the paper onto the copper. After soaking in water to remove the paper, the toner now transferred to the copper laminate acts as an etch resist.<ref>[http://fullnet.com/~tomg/gooteepc.htm ''Easy Printed Circuit Board Fabrication, Using Laser Printer Toner Transfer''] by Thomas P. Gootee, 2007</ref> This can also be used to print component side parts and legends. ''Press'n'Peel'' is similar to this method. If you don't tin the board, coat the copper laminate with rework flux to prevent it oxidising.<ref name="mh">''[http://www.electricstuff.co.uk/pcbs.html How to make really really good homemade PCBs]'' by Mike Harrison</ref>
=== Photo resist ===
Print the PCB layout onto clear or translucent film
== Etching ==
Etching the PCB in Ferric Chloride (FeCl<sub>3</sub>) solution removes the copper not masked by the etch resist. Take precautions because FeCl<sub>3</sub> will deeply stain anything it comes in contact with.
=== Safe disposal of FeCl<sub>3</sub> ===
FeCl<sub>3</sub> is toxic and harmful to the environment
=== Alternative etchant to FeCl<sub>3</sub> ===
Cupric chloride etchant is very similar to ferric chloride, but is simple to regenerate, there are no disposal problems,
== Tinning ==
Tin-plating a PCB makes it a lot easier to solder and makes working with [[SMD]]s much easier. Use room-temperature tin plating crystals e.g. ''Seno Immerse Tin Crystals'', these produce a good finish in a few minutes but can be expensive. Only make enough tinning solution to cover a PCB in the tinning tray. Keep the solution in a concertina-type bottle to exclude air. Also avoid contamination with metals other than copper. Thoroughly rinse and dry the PCB before tinning. Use a separate tray and pair of tongs specifically for tinning, and rinse them after use. If the solution stops tinning, discard it, clean & rinse the tray, and make up a fresh solution. A cool tinning solution will usually prevent tinning so ensure the temperature of the tinning solution is at least 25ºC, but not more than 40ºC, put the bottle in hot water to warm it up.<ref name="mh" />
Strip the etch resist thoroughly.<!-- acetone with toner or methylated spirits? --> Rub the copper surface with a plastic scourer until it is bright and shiny all over, wipe with a paper towel and immediately immerse the board in the tinning solution. Take care not to touch the copper surface after cleaning, as fingermarks will impair plating. Within about 30 seconds the copper should turn a silver colour, leave the board for about 5 minutes, agitating occasionally. For double-sided PCBs ensure the solution can get to both sides. Rinse the board thoroughly, and dry with paper towel to remove any tinning crystal deposits, which can spoil the finish. If the board isn't going to be soldered for a day or two, coat it either with a rework flux spray or a flux pen.<ref name="mh" />
== Drilling ==
Use a drill press and a drill with a collet not a chuck. Use a 0.
To use a [https://en.wikipedia.org/wiki/Numerical_control CNC] drill first generate an ''Excellon'' or ''NC drill'' file.
== See also ==
* [[PCB fabrication (outsourcing)]]
* [[Screen printing]]
== References ==
{{reflist}}
== Further reading ==
* ''How to Design and Make Your Own PCBs'' by R. Penfold, Babani, 1983, ISBN
* ''Fabricating Printed Circuit Boards''' by Jon Varteresian, Newnes, 2002, ISBN
* ''Build Your Own Printed Circuit Board'' by Al Williams, Tab, 2003, ISBN
== External links ==
* [http://www.electricstuff.co.uk/pcbs.html How to make really really good homemade PCBs] by Mike Harrison
* Wikipedia:[https://en.wikipedia.org/wiki/Comparison_of_EDA_software Comparison of EDA software]
* [http://www.opencircuits.com/Printed_Circuit_Boards Printed_Circuit_Boards] at Open Circuits
* [http://www.megauk.com/ Mega Electronics] UK manufacturer and supplier of products for printed circuit board production, etc.
* [http://quinndunki.com/blondihacks/?p=835 PCB Etching Mega Redux] by Quinn Dunki, 15 February 2012
* ''[http://www.instructables.com/id/Stop-using-Ferric-Chloride-etchant!--A-better-etc/?ALLSTEPS Stop using Ferric Chloride etchant! (A better etching solution.)]'' by The Real Elliot, Instructables
* ''[http://www.instructables.com/id/Killer-PCBs/?ALLSTEPS Killer PCBs]'' by incoherent, Instructables
* [http://tech.groups.yahoo.com/group/Homebrew_PCBs/ Homebrew PCBs] Yahoo group
[[Category:PCB]]
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