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Re: PCB through hole activation for copper plating
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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Re: PCB through hole activation for copper plating
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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Re: PCB through hole activation for copper plating
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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PCB through hole activation for copper plating
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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Re: DIY Toaster Reflow oven
Jim,
I originally used a Silicon Horizon reflow oven controller board which cost around $75. I tested it and then put it up on a shelf until I got around to track down all the remaining parts to do the actual build. I bought via Amazon (its generally a crap-shoot regarding product quality in my opinion), a Black & Decker InfraWave 1200 Watt with crystal heating elements (exhibits shorter thermal inertia) instead of the iron heating elements. I hacked out all the guts and then lined the insides of the oven, between the inner and outer walls of it with high fibre-glass insulation sheeting, which I custom fit. Else ya can't touch the oven while it is operating. My unit is cool to the touch, even during 36 hour component baking periods. When I got the controller down, it worked three times and failed. I contacted the company and it had gone out of business. The schematics & source code had been promised to be on the CD shipped with the controller, but alas was not. So I reversed engineered the hardware and fixed it and in the mean time I acquired all of the source code from other users. To make a long story short, I eventually replaced that controller with the following, excellent controller: Depending on options it starts at $100 bucks, for the controller and the display screen. It works very well and I've used it for many projects over the past 7 years or so. What ever you do, be sure to acquire the oven with an internal fan. The B&D Infrawave does not have one internal, so I had to mount a small blower on the outside. Also the 'gold' thermal reflection tape really makes a difference in the internal thermal cavity stability. Best Regards tron nee -- SETV - Autonomous Instrumentation Platforms for the Detection & Measurement of Suspected ExtraTerrestrial Objects |
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Re: DIY Toaster Reflow oven
You do not want to use a relay (EMI), but an SSR with crossover detection, also called zero voltage switch. I? use my own PWM method by enabling X periods over a one thousand period timeframe. 1000 periods at 60 hertz is less than 20 seconds, so I can finely tune the temperature ramp in real time.
If your heater was much faster, you could reduce the timeframe to 100 periods but that cause other concerns. Just my few cents worth. Jean-Paul? N1JPL? |
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Re: DIY Toaster Reflow oven
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On Jun 5, 2020, at 3:56 PM, Steven Dick <sbdick@...> wrote:
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Re: DIY Toaster Reflow oven
There was a note from Adafruit just a few months ago about a Reflow Oven project based on their Micro-Python board (can't remember the name of it) along with source code (again Micro-Python).? The Adafruit board is overpriced, in my opinion) but wouldn't be too hard to replicate with a Blue-Pill or Black-Pill from Ali or BangGood.? Coupled with a cheap toaster oven this would be a very inexpensive way to go!
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Re: DIY Toaster Reflow oven
A good thing to keep in mind is that, where a contactor/relay rated at 30A will run just fine at 15A with no special effort, a 40A SSR will require a large heat sink and possibly forced air cooling, or at least mount it for best natural airflow.
Plus the issue of counterfeit and creatively rated specs. I've noticed that many of the heat sinks for SSRs have rather thin aluminum extrusion, here is one from Aliexpress: This one from brewpi has a thicker extrusion: Personally, I prefer something like this with the fins right out of the plate, as a shorter path means lower thermal resistance: ? Mount it for vertical airflow with large, well placed holes in the case, should get rid of heat very well. -- Steven Greenfield AE7HD |
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Re: DIY Toaster Reflow oven
Here's the manual for my Inkbird ITC106VH? (covers other models too)?
They have models for energizing external relay coils @ 12-24 and 120-240v if you don't like SSRs.? Much better than building your own IMHO....unless you want the experience and will probably spend more. There's really nothing fiddly about it if you're comparing to doing it all yourself. It works from -50 -> +1,300 deg C, 0.5 seconds control loop, 0.1 deg C control and will work as-is if you want to do your own timing manually. I built a small stand for mine and wired in series with a short AC extension cord. An easy project. A few years ago I bought a stuffed PCB from SparkFun that did this PID control plus reflow timing for US$85 but it's no longer available. Good luck? ? -mike |
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Re: DIY Toaster Reflow oven
开云体育The ones intended for 3D printer hot-ends should be ok as they run at 200-250C. ? 贬辞飞别惫别谤… ? As you say, read the specs.? The 3D printer ones have Teflon insulation which is nice, but that usually only covers the first couple of inches, the rest might well be standard PVC coated wire.? Ok for a 3D printer, not so much for an oven where the sensor needs to go in the middle of the plate. ? Tony ? ? ? From: [email protected] [mailto:[email protected]] On Behalf Of Steven Greenfield AE7HD via groups.io
Sent: Wednesday, 3 June 2020 11:45 PM To: [email protected] Subject: Re: [homebrewpcbs] DIY Toaster Reflow oven ? I don't know if 3950 is a generic term, or what, but Adafruit lists what they call an "3950 NTC" thermistor that is a 10k, max 105C with epoxy coating and vinyl wire. So read the specs of what you are ordering. I've been bit by that before on type K thermocouples, where some I bought had a sleeve that turned out to be plain heatshrink. So it burned to black carbon when I Kapton taped it to the side of a soldering iron... |
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Re: DIY Toaster Reflow oven
I don't know if 3950 is a generic term, or what, but Adafruit lists what they call an "3950 NTC" thermistor that is a 10k, max 105C with epoxy coating and vinyl wire. So read the specs of what you are ordering. I've been bit by that before on type K thermocouples, where some I bought had a sleeve that turned out to be plain heatshrink. So it burned to black carbon when I Kapton taped it to the side of a soldering iron...
Sure, no reason not to use something simpler to interface for the temperature. It doesn't really need a 1% resistor, just one that is temperature stable. So don't get them out of your old junkbox of grampa's carbon composition resistors. -- Steven Greenfield AE7HD |
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Re: 3D printer scribe
Hey Brent, sorry for the slow reply. Thanks for all your compliments! Some initial thoughts from my experience with the scriber, and the pressure issues you've faced:
I ended up using a spring from a ball-point pen behind the scriber tip. That lets it have a range of gentle pressure, and the amount of pressure is adjusted by moving an optical endstop. It really doesn't take much to scratch off the paint, and the less you use the less the tip drags and goes out of alignment. You can also make much faster paths, which allows more concentric laps around each area without increasing the "print" time too much. The spring-backed scriber raised the challenge of letting the scriber move up and down freely while staying aligned. That's what the odd assembly with 4 (actually 6) bearings allows to happen. There must be a simpler solution, but that's what I came up with. I don't know if any of that is helpful for your setup, or if any of that could be adapted. I would love to follow your progress on this, so, even though I took a while to reply, I hope you keep updating us! |
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Re: DIY Toaster Reflow oven
This is the Pid controller you want. High quality and function .?
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https://www.amazon.com/TEMPERATURE-CONTROLLER-RAMP-SOAK-OUTPUT/dp/B01DC3KNS0/ref=mp_s_a_1_4?dchild=1&keywords=syl-2352p&qid=1591184860&sr=8-4
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Re: DIY Toaster Reflow oven
开云体育The picture didn’t come thru, but the usual aluminium-backed boards that most 3D printers use are only meant to be run at 100C-ish.? I think maximum is about 150C for that stuff. ? The silicone heaters go up to 350C, more than enough for SMD soldering.? For the price you might as well go and buy a cheap board heater. ? No real advantage in 3D printing for using a silicon mat over a PCB one except the mains rated ones tend to be high wattage so they heat up faster. ? Tony ? ? ? From: [email protected] [mailto:[email protected]] On Behalf Of Rob via groups.io
Sent: Wednesday, 3 June 2020 5:10 PM To: [email protected] Subject: Re: [homebrewpcbs] DIY Toaster Reflow oven ? Has anyone played with 3D printer heat tables for SMD ? ? The PCB are aluminium backed, so that sucks out any heat if you try to use a soldering iron, or even a hot air gun at times. ? |
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Re: DIY Toaster Reflow oven
开云体育Has anyone played with 3D printer heat tables for SMD ?
The PCB are aluminium backed, so that sucks out
any heat if you try to use a soldering iron, or even a hot air
gun at times. |
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Re: DIY Toaster Reflow oven
开云体育Yeah, they’ll work.? I was thinking of 10K thermistors for some reason. ? Don’t forget your lookup table. ? Tony ? ? ? From: [email protected] [mailto:[email protected]] On Behalf Of Rob via groups.io
Sent: Wednesday, 3 June 2020 12:35 PM To: [email protected] Subject: Re: [homebrewpcbs] DIY Toaster Reflow oven ? hmmm... wow...???? I did not know that.... 200 C limit ?!?!? I had huge success measuring 350 F? with mine....? laser printer toner temps..... and I thought the SMD cooking solder target was 210 C?? which is 410 F which is no where near 300 C?? 572 F?? written on the NTC3950 specifications. ? I think this definitely warrants some more research. =========================================================================================================== I found this on AMAZON: The temperature of the new NTC3950 thermistor can be up to 300 degree celsius. Easy to instal on your 3D printer or other DIY project with the ends of the wires are pre-stripped. Length: 1m/39.37 Inches. Accuracy: +/- 1%. ? ? On 06/02/2020 10:15 PM, Tony Smith wrote:
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Steven Greenfield AE7HD