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PCB through hole activation for copper plating
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Does anyone on the list have access to Calcium Hypophosphite?? This stuff is impossible to find in the US, being a "controlled substance".? For crying out loud. I really can't see the point considering the volumes we are talking about!
Alternatively, do any of you chemistry majors out there know of a substitute formula using more easily available chemicals? |
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Jim Higgins
Hypophosphites can be used in the manufacture of methamphetamine and some other controlled substances requiring similar reactions, so it's hard to get in the USA. No telling what you'll get from Asian vendors on Ebay, or if you risk seizure by customs. If you do order from them, you better specify DHL shipping or you might not have it before autumn.
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If the PCBs are only 2-sided, and you're willing to drill 0.062" holes, you might try brass eyelets available for this purpose from Mouser. The holes will be 0.045" when the eyelets are in place. Or solder copper wire in the holes... something I wouldn't want to do if there are many holes... but for a one of a kind home-made board that's the way I'd go if I could tolerate the required hole size. Jim H Received from Terry Gray at 6/10/2020 23:58 UTC: Does anyone on the list have access to Calcium Hypophosphite? This stuff is impossible to find in the US, being a "controlled substance". For crying out loud. I really can't see the point considering the volumes we are talking about! |
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what is the reason ... process....? to use Calcium Hypophosphite when home brewing a PCB?
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On 06/11/2020 01:29 PM, Jim Higgins wrote:
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Hi all, the reason is drilled holes activation: the standard way to make conductive holes is to drill them on a blank board, then "activate" (get them to have some conductivity) the internal surface of the drilled holes, then do electroplating of copper to grow a sufficient layer of copper inside the holes. If I remember correctly, there are other ways to activate holes. A long time ago, I experimented with it, with limited success. I tried to replicate this: The best I could manage was to get 95% plating of the holes, which is not what you want. What I mean is: I did test boards while tuning the process, with a couple hundreds holes, trying to plate them, then measure each and every single one of them with a milli-ohm meter. And in every single batch, I had failed holes, either with zero connectivity, or too high of a resistance. I gave up, but maybe someone could be more successful with it? C. On Thu, Jun 11, 2020 at 8:26 PM Rob via <roomberg=[email protected]> wrote: what is the reason ... process....? to use Calcium Hypophosphite when |
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One might also check out the jewelry sellers on "etsy.com"....I purchased
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some VERY tiny brass rivets on a site (sorry, no link...Google) and they also had eyelets. Charlie On Thu, 11 Jun 2020 17:29:51 +0000 "Jim Higgins" <HigginsJ@...> writes:
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Thanks for your suggestions but did you read where? I am specifically asking about "through-hole activation" and not for alternatives?? I have used eyelets but really don't like them due to a too large hole size requirement.? I have also gone the soldered wire route but that is only good for vias, and useless for connectors.
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There is an Instructable on this very subject.
I have had no luck with the conductive ink or paint method, never getting close to 95%, which is why I am inquiring about the chemical method. If I can't obtain Calcium Hypophosphite then I would like to find an alternative chemical method that doesn't require it. |
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An electroplating shop might be cool and give you a small amount. On Thu, Jun 11, 2020 at 1:37 PM Charlie Hansen <n0tt1@...> wrote: One might also check out the jewelry sellers on ""....I purchased |
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Jim Higgins
You know what? You asked a question and I answered on point... and then amplified separately in hopes of helping. You are no worse off now than you were when you started, but now you act like I'm a problem. Google is your friend.
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Jim H Received from Terry Gray at 6/12/2020 00:13 UTC: Thanks for your suggestions but did you read where I am specifically asking about "through-hole activation" and not for alternatives? I have used eyelets but really don't like them due to a too large hole size requirement. I have also gone the soldered wire route but that is only good for vias, and useless for connectors. |
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There are another method that don't use calcium hypophosphite. It's in this site (in portuguese, but google translate can be effective to get the essential): Anyway, in that site there are a homebrew solution to manufacture calcium hypophosphite too. Best regards Matheus
On Thursday, June 11, 2020, 9:19:23 PM GMT-3, Terry Gray <twgray2007@...> wrote:
There is an Instructable on this very subject. I have had no luck with the conductive ink or paint method, never getting close to 95%, which is why I am inquiring about the chemical method. If I can't obtain Calcium Hypophosphite then I would like to find an alternative chemical method that doesn't require it. |
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Thanks everyone for your replies and sugestions.
Thanks, Matheus!? While not exactly what I was hoping for, this is a reasonable solution.? I will give a shot at trying to "make" calcium hypophosphite.? Been a looong time since I dabbled in chemistry but maybe it is like riding a bicycle and you never forget how! And, for anyone who cares, calcium hypophosphite is available from several vendors on alibaba.? They all advertise the stuff for pennies per gram but when you request a quote all of them come back in the neighborhood of $100 per 500G.? Then when you tell them you are in the US, the price jumps up to about $500 per 500G.? This is well beyond the range of most hobbyists...at least well beyond mine.? Now I am off to price diy calcium hypophosphite! Thanks again! |
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Jim Higgins
Received from Matheus Costa via groups.io at 6/12/2020 15:16 UTC:
There are another method that don't use calcium hypophosphite. It's in this site (in portuguese, but google translate can be effective to get the essential): The method at this site starts with Sodium Hypophosphite, which is as much a controlled substance as Calcium Hypophosphite. Jim H |
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I did have an idea, which may or may not work:
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It's not a replacement for plated through holes, but may address the same problem. I was working on a strictly mechanical basis, which meant eyelets or jumper wires Eyelets have a history of being badly soldered and not being as permanent as people would want. What I thought of was an automated system that would push a piece of soft copper wire into a hole. From the bottom it would be center punched to swage it in the hole (and it wouldn't be flush) Then at the top, cut off a bit above flush, and swaged to cover the top pad as much as possible. What I'm thinking of is effectively a solid rivet. While I was thinking of this reply, I thought that a wire protuded through the board, then bent at right angles. Then at the top, cut off the wire above the surface (distance matters!), then bend the wire over to make a C shaped jumper between top and bottom layers. The idea is that this could be automated with a special setup that had the appropriate wire benders as needed. Solder that, and you've got a better solution, I think. Harvey On 6/12/2020 6:53 PM, Jim Higgins wrote:
Received from Matheus Costa via groups.io at 6/12/2020 15:16 UTC:There are another method that don't use calcium hypophosphite. It's in this site (in portuguese, but google translate can be effective to get the essential): |
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And again, not looking for a mechanical solution.? Already tried eyelets...they suck for so many reasons, the foremost being inconsistency of connection. Already tried soldered wires...this also sucks...mainly being a PITA to solder and they only address vias.? Any through hole connectors can't be done this way.
Also have tried conductive inks, paints, resins.? Never got more than about 75% of the holes being conductive. |
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-------- Original message -------- From: Terry Gray <twgray2007@...> Date: 6/12/20 6:45 PM (GMT-06:00) Subject: Re: [homebrewpcbs] PCB through hole activation for copper plating Also have tried conductive inks, paints, resins.? Never got more than about 75% of the holes being conductive. |
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Jim, Sodium Hypophosphite Monohydrate is apparently a controlled substance but for whatever reason it seems to be much easier and far cheaper to obtain than its cousin Calcium Hypophosphite, and I haven't talked to anyone that knows why!? I can obtain it from several places in the US as well as from several Chinese vendors on Alibaba for a much lower price than CH.
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I think that are difficult to understand all the content of the site, but I want put focus in this process that doesn't use calcium hypophosphite:
On Friday, June 12, 2020, 5:53:15 PM GMT-3, Terry Gray <twgray2007@...> wrote:
Thanks everyone for your replies and sugestions. Thanks, Matheus!? While not exactly what I was hoping for, this is a reasonable solution.? I will give a shot at trying to "make" calcium hypophosphite.? Been a looong time since I dabbled in chemistry but maybe it is like riding a bicycle and you never forget how! And, for anyone who cares, calcium hypophosphite is available from several vendors on alibaba.? They all advertise the stuff for pennies per gram but when you request a quote all of them come back in the neighborhood of $100 per 500G.? Then when you tell them you are in the US, the price jumps up to about $500 per 500G.? This is well beyond the range of most hobbyists...at least well beyond mine.? Now I am off to price diy calcium hypophosphite! Thanks again! |
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