Elementary questions about electronics :: Beginner looking for advice


	Beginner looking for advice Hello All, Please excuse the beginner questions; this is my first attempt at etching a PCB. I bought some 2oz dbl sided boards, and will be etching them using Sodium Persulphate. I've done the traces using press-n-peal blue. I do not yet have an elaborate set up, and I'm looking for any advice your willing to share. I've read that I should add 1/2lb Sodium Persulphate crystals to 1 gallon of warm water. The board should be submerged until the copper that is not protected is dissolved. Am I missing anything? Any tips or tricks that would be helpful? will this solution be strong enough? How does one dispose of the remaining etching solution? Lastly the board is a breakout of sorts, taking a db25 and directing the individual wires to terminal connectors. The board will be exposed to short pulses (1-3 seconds) of 24VDC @ up to 5 amps. The traces are 1/16th of an inch thick and separated by only 1/32th of an inch in many places. This board will not be used for transferring signals, just on or off for short durations. Does this sound ok? Thanks, Brian - Hide quoted text - Cat wrote: > Hello All, > Please excuse the beginner questions; this is my first attempt at > etching a PCB. > I bought some 2oz dbl sided boards, and will be etching them using > Sodium Persulphate. I've done the traces using press-n-peal blue. I do > not yet have an elaborate set up, and I'm looking for any advice your > willing to share. > I've read that I should add 1/2lb Sodium Persulphate crystals to 1 > gallon of warm water. The board should be submerged until the copper > that is not protected is dissolved. Am I missing anything? Any tips or > tricks that would be helpful? will this solution be strong enough? How > does one dispose of the remaining etching solution? > Lastly the board is a breakout of sorts, taking a db25 and directing > the individual wires to terminal connectors. The board will be exposed > to short pulses (1-3 seconds) of 24VDC @ up to 5 amps. The traces are > 1/16th of an inch thick and separated by only 1/32th of an inch in > many places. This board will not be used for transferring signals, > just on or off for short durations. Does this sound ok? > Thanks, > Brian sounds fine how ever, I think for the 5 amps you're using, you may want to consider using wider traces for that path. And as far as the etching goes, warming up the solution makes it etch faster. -- "I'm never wrong, once i thought i was, but was mistaken" Real Programmers Do things like this. http://webpages.charter.net/jamie_5 -----------------------------------------------Reply----------------------------------------------- "Jamie" <jamie_ka1lpa_not_valid_after_ka1l@charter.net> wrote in message news:udu0i.1024$Qq6.563@newsfe12.lga... - Hide quoted text - > Cat wrote: >> Hello All, >> Please excuse the beginner questions; this is my first attempt at >> etching a PCB. >> I bought some 2oz dbl sided boards, and will be etching them using >> Sodium Persulphate. I've done the traces using press-n-peal blue. I do >> not yet have an elaborate set up, and I'm looking for any advice your >> willing to share. >> I've read that I should add 1/2lb Sodium Persulphate crystals to 1 >> gallon of warm water. The board should be submerged until the copper >> that is not protected is dissolved. Am I missing anything? Any tips or >> tricks that would be helpful? will this solution be strong enough? How >> does one dispose of the remaining etching solution? >> Lastly the board is a breakout of sorts, taking a db25 and directing >> the individual wires to terminal connectors. The board will be exposed >> to short pulses (1-3 seconds) of 24VDC @ up to 5 amps. The traces are >> 1/16th of an inch thick and separated by only 1/32th of an inch in >> many places. This board will not be used for transferring signals, >> just on or off for short durations. Does this sound ok? >> Thanks, >> Brian > sounds fine how ever, I think for the 5 amps you're using, you may want > to consider using wider traces for that path. > And as far as the etching goes, warming up the solution makes it > etch faster. According to my trace width calculator, 5 amps on a 62 mil trace with standard 1 ounce copper will only cause a temperature rise of about 25 C, so 1/16 wide is fine, especially for short pulses. I found the calculator (an Excel spreadsheet) on an internet search. I can send it to you if you wish. Try http://www.geocities.com/suppanz/TraceWidth.htm. When I etched my own boards many moons ago, I found that it was very important to clean the copper very thoroughly before applying resist. ScotchBrite with soap and water worked well. Just a little bit of oil or oxide on the exposed copper made for slow etching in those areas, and overetching under the resist. Also, I found it better to drill the holes before etching. Otherwise, sometimes the drill would catch the pad and pull it loose. Good luck. Paul -----------------------------------------------Reply----------------------------------------------- On 9 May 2007 17:36:39 -0700, Cat <paone@gmail.com> wrote: - Hide quoted text - >Hello All, >Please excuse the beginner questions; this is my first attempt at >etching a PCB. >I bought some 2oz dbl sided boards, and will be etching them using >Sodium Persulphate. I've done the traces using press-n-peal blue. I do >not yet have an elaborate set up, and I'm looking for any advice your >willing to share. >I've read that I should add 1/2lb Sodium Persulphate crystals to 1 >gallon of warm water. The board should be submerged until the copper >that is not protected is dissolved. Am I missing anything? Any tips or >tricks that would be helpful? will this solution be strong enough? How >does one dispose of the remaining etching solution? >Lastly the board is a breakout of sorts, taking a db25 and directing >the individual wires to terminal connectors. The board will be exposed >to short pulses (1-3 seconds) of 24VDC @ up to 5 amps. The traces are >1/16th of an inch thick and separated by only 1/32th of an inch in >many places. This board will not be used for transferring signals, >just on or off for short durations. Does this sound ok? >Thanks, >Brian Are you sure it wasn't Ammonium Persulphate you bought? That's what I use and it is mixed at 200gm per litre of water. -----------------------------------------------Reply----------------------------------------------- "Cat" <paone@gmail.com> wrote in message news:1178757399.032168.128060@q75g2000hsh.googlegroups.com... - Hide quoted text - > Hello All, > Please excuse the beginner questions; this is my first attempt at > etching a PCB. > I bought some 2oz dbl sided boards, and will be etching them using > Sodium Persulphate. I've done the traces using press-n-peal blue. I do > not yet have an elaborate set up, and I'm looking for any advice your > willing to share. > I've read that I should add 1/2lb Sodium Persulphate crystals to 1 > gallon of warm water. The board should be submerged until the copper > that is not protected is dissolved. Am I missing anything? Any tips or > tricks that would be helpful? will this solution be strong enough? How > does one dispose of the remaining etching solution? > Lastly the board is a breakout of sorts, taking a db25 and directing > the individual wires to terminal connectors. The board will be exposed > to short pulses (1-3 seconds) of 24VDC @ up to 5 amps. The traces are > 1/16th of an inch thick and separated by only 1/32th of an inch in > many places. This board will not be used for transferring signals, > just on or off for short durations. Does this sound ok? > Thanks, > Brian Use in a ventilated area, and follow all precautions for this chemical. Sodium Persulphate is a strong oxidizer and will combine with many things to make it dangerous. Read the MSDS. You mentioned double sided boards, DS boards are a little tricky for a beginner and you will be putting a lot of unused copper in the mix. Good luck, Tom -----------------------------------------------Reply----------------------------------------------- Thanks for the advice everyone. The more I read the more I wondered if I was going to need a fish tank heater and bubbler, etc. On May 9, 9:27 pm, "Paul E. Schoen" <pst@smart.net> wrote: > According to my trace width calculator, 5 amps on a 62 mil trace with > standard 1 ounce copper will only cause a temperature rise of about 25 C, > so 1/16 wide is fine, especially for short pulses. I was most worried about the closeness of traces (only 1/32th of an inch) glad no one points this out as a problem. > Also, I found it better to drill the holes before etching. Otherwise, > sometimes the drill would catch the pad and pull it loose. This is good advice I'd not seen anyone recommend this yet. I will give it a go before etching. How about that green lacquer that is on a commercial board. Does anyone here have any experience applying this to a home etched board? -----------------------------------------------Reply----------------------------------------------- - Hide quoted text - On Thu, 10 May 2007 03:19:14 -0700, Cat wrote: > Thanks for the advice everyone. The more I read the more I wondered if > I was going to need a fish tank heater and bubbler, etc. > On May 9, 9:27 pm, "Paul E. Schoen" <pst@smart.net> wrote: >> According to my trace width calculator, 5 amps on a 62 mil trace with >> standard 1 ounce copper will only cause a temperature rise of about 25 C, >> so 1/16 wide is fine, especially for short pulses. > I was most worried about the closeness of traces (only 1/32th of an > inch) glad no one points this out as a problem. >> Also, I found it better to drill the holes before etching. Otherwise, >> sometimes the drill would catch the pad and pull it loose. > This is good advice I'd not seen anyone recommend this yet. I will > give it a go before etching. > How about that green lacquer that is on a commercial board. Does > anyone here have any experience applying this to a home etched board? That green coating is the solder mask. It keeps the wave-soldering process from coating all of the copper, conserving solder. A hand-soldered board doesn't really need it.

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Elementary questions about electronics

Beginner looking for advice