best glue for FR4+metal - Page 1
Forum section: electronics / general

author: coppercone2
author_rank: Super Contributor
timestamp: February 23, 2025, 09:25:23 am
content: IT sounds simple but my attempt to glue together a diy PCB with 24 hour JB weld (after cleaning and deep scratching and more cleaning) lead to a shitty result, that is the metal popped off totally when I cut it with a shear.This is for attempting things like heavyweight boards. Get bare copper and FR4, clean/sand/clean and then press together modestly during the cure.What do you think the best glue to try would be, most of mine other then JB are pretty expired and I need to buy more.I thought of DP270, DP420, DP110Is this just a issue of the glue being too rigid?Like JB weld sucks for this! totally. I thought it would be easy!! The big problem is that it needs to be high temperature (solderable), which is why I thought JB weld would be the best. It reminds me of what happens when you do floor tiles wrong.I also wanted to experiment with things like steel or other material PCBs.And it needs to be acid resistant, for experiments involving heavyweight etching (out of pure interest in trying to tune the process)

author: Benta
author_rank: Super Contributor
timestamp: February 24, 2025, 01:21:39 am
content: FR4 to metal is no big deal. You just need the right epoxy glue and the right setup.First, both contact surfaces need to be roughed up a bit. Easy: fine grit sandpaper plus acetone for degreasing.Second, you need to concoct some mechanical "thingy" that will press the surfaces togetherevenly and tightlyAND keep them aligned no matter what. Preferably spring loaded (you'll see why).Third, select the right glue. I've no idea what "JB Weld" is, I use "UHU Endfest 300", prolly about the same. Basically you need a 2-component, 24-hour tacky epoxy glue.Fourth, wait until your wife is out of the house, then preheat your oven to 180 C. Place baking paper on the grid/plate.Fifth, apply glue to the surfaces, press them together (avoid air bubbles), mount your pressure/alignment "thingy" and stick the whole thing in the oven for 10 minutes.Done.Let it all cool off, and I promise you you'll have a glue joint that will rip the FR-4 apart before breaking.PS: I looked at the JB Weld site. I'd say you just need the basic type. The other products look like flim-flam.

author: coppercone2
author_rank: Super Contributor
timestamp: February 24, 2025, 01:50:02 am
content: Thats what I did, it was baked too (after 6 hour cure). The thick copper sheet popped off when it was sheared.I used lab acetone, 100 grit sand paper and task wipesThe JB weld is very hard when done. I thought it might be the problem. It's like rockfor pressure, it was set with a aluminum block on top to keep it compressedI thought maybe the trick is to use epoxy without fillers (clear) or at least little fillers, JB weld is very full of fillers I think.I thought it might not like copper for some reason. I never had a real reason to glue copper to anything before. Usually things do alot better

author: themadhippy
author_rank: Super Contributor
timestamp: February 24, 2025, 01:59:01 am
content: ive stuck pcb boards to aluminum with nothing more exotic than uhu,only prep was a quick rough up with sandpaper

author: jpanhalt
author_rank: Super Contributor
timestamp: February 24, 2025, 02:01:22 am
content: Most epoxy catalysts are basic. Like glues like. Epoxy used properly works. Cyanoacrylate adhesives, which are base catalyzed, should also work. In a recent projects, I had plated through holes that aligned. No adhesive was needed . I used 2 or 3 welded rivets (short pieces of wire soldered at both ends (attachment). Worked well and was very hard to separate.Edit: For aluminum, CA works great because of the basic surface.

author: coppercone2
author_rank: Super Contributor
timestamp: February 24, 2025, 02:12:06 am
content: well IDK, I think I will try DP270 because at least that one is useful to always have in stock, and it is meant for circuit boards.It sounds like this should not be a problem.But, no one specifically knows if there is some kind of... chemical problem with copper? If I made basically any other joint like this I would expect it to be extremely tough.Could it be like interfering with the curing because of some kind of catalytic action? Copper is pretty chemically reactive. Aluminum even more so but I think its usually at least 1 atom oxidized.I thought maybe putting a flash-nickel plate on it would help, if its screwing with epoxyAnd I am thinking if copper is bad, silver must be worse.This is what Mother told me:AI OverviewThe Problem With Epoxy | SageWaterCopper can react with epoxy, which can lead to epoxy decomposition and reduced bonding strength. This can cause corrosion, leaks, and blockages.Maybe it gets fucked up from bake curing? But I also think I tried un-baked after a day or two. I re-sanded this copper and FR4 through like 4 different attempts, I started this back in the summer and gave up after repeated failures. And there was also a test with IPA instead of acetone that failed.It just pops off when you shear part of it off. a commercial PCB has 0 chance of this happening. And this one was cured in a calibrated lab oven (not my DIY thing) when I did heat it ($$ $ $ $), very slow ramp and basically no over shoot (modern fischer or something), its regularly verified and calibrated because it does important thingsperhaps there is some inhibitor added in commercial PCB manufacture epoxy?

author: coppercone2
author_rank: Super Contributor
timestamp: February 24, 2025, 02:30:08 am
content: https://www.eevblog.com/forum/manufacture/what-bonds-the-copper-to-fr4-or-how-could-i-make-a-custom-shaped-board/msg111870/#msg111870HMM. It looks like you might neeed a patinaBut WTF. I renember teslacoil saying that the RF flows under the PCB (not top side of copper), meaning if thats messed up, you have shitty RF performance, its supposed to be beautiful there (i have a thread asking about surface finish of PCB's) . The idea being that if you polish a PCB it won't actually have better microwave performance.Contradictions....Are we really routing signals through copper oxide on chimerical PCBs?

author: Smokey
author_rank: Super Contributor
timestamp: February 24, 2025, 03:00:10 am
content: Thermal epoxy + mounting screws threaded in the corners to hold it all together?What is the end goal? Is it thermal or structural reasons for bonding to metal? Could you just get an aluminum core PCB and be done?

author: coppercone2
author_rank: Super Contributor
timestamp: February 24, 2025, 03:37:03 am
content: I want my own thick copper pcb blank thats like a commercial one, then I can have a blank PCB of arbitrary material and thickness that I make from fiberglass and sheet metal that can be used in experiments of PCB manufacture like milling, heavy etching, etc.I have a fair assortment of sheet/foil metals that can be used for whatever at this point

author: sleemanj
author_rank: Super Contributor
timestamp: February 24, 2025, 04:05:00 am
content: My first suggestion would be... don't use a shear to cut it. Use a carbide tipped tile cutter/scorer, to cut through the copper layer, score both sides, and snap. A shear will put much more stress on the adhesive joint.My second suggestion would be... maybe a contact adhesive, it will be more flexible.Trouble will be finding a contact adhesive that can stand up to high temperature. If you are hand soldering, or using low-temperature solder, it migh not be an issue.ADOS F38 was the highest I could find in a google for retail available ones, it claims to stand 175°C but maybe it would do more for long enough for reflow, or at least for hand-soldering.

author: coppercone2
author_rank: Super Contributor
timestamp: February 24, 2025, 04:07:27 am
content: I am thinking maybe just to heat it, bond it, then clean it after its bonded on the other side. It should oxidize. ? leave it on a hot plate?

author: coppercone2
author_rank: Super Contributor
timestamp: February 24, 2025, 05:07:22 am
content: I tried leaving a penny in oxy-clean, it looks like it just got cleaner instead of oxidizingI might leave a penny on a hot plate next. Maybe upside down jar with oxygen squirted into it from a tank too?I see there are some patina makers like copper blacker, but these have sulfur compounds in them. I think they make sulfates, which does not seem to fall into the thing free electron said where its oxidized... so it might be the wrong direction to go inI cut a square, cleaned it with strong soap, and put it in the toaster oven at 500F. I wonder what this simple procedure will result in

author: coppercone2
author_rank: Super Contributor
timestamp: February 24, 2025, 06:33:41 am
content: The growth rate for oven is slow. It looks like black oxide copper coating has a mil-spec too, and its related to adhesion performance.it looks like similar to black oxide coating for steel, you dip it in hot chlorite bath or something.http://everyspec.com/MIL-SPECS/MIL-SPECS-MIL-F/MIL-F-495E_4311/Probably not the hardest thing to oxidize a metalhttps://www.researchgate.net/publication/3889173_Optimization_of_black_oxide_coating_thickness_as_adhesion_promoter_for_copper_substratehowever......I wonder if weaker DIY non-coated PCB can have superior RF performance then standard PCB because you can glue mirror finished copper....for a two layer board, you won't have the black oxide on the stripline surfaceI am thinking, forget the coatings and just glue some mirror polished silver plated copper to the board and be gentle with it, you are right that surviving shears should not be high on the priority list for a DIY project, but it might merit investigation for heavy weight stuff. I think I will try birchwood products though before I go into this rabbit hole

author: Poroit
author_rank: Frequent Contributor
timestamp: February 24, 2025, 08:32:33 am
content: Try Sika 11FC.I have used successfully on heaps of different materials.

author: coppercone2
author_rank: Super Contributor
timestamp: February 25, 2025, 08:58:23 am
content: The oxyclean penny still did nothing, so I bought some sodium chlorite, it seems to be referenced in many papers as a key reagent for the growth of films meant for adhesion on copper bearing materialsI think making a 1/8 inch thick ground plane for a voltage follower audio grade circuit will bring clarity and deep tone to music

author: langwadt
author_rank: Super Contributor
timestamp: February 25, 2025, 12:19:53 pm
content: Quote from: coppercone2 on February 25, 2025, 08:58:23 amneed to be done at full moon by naked virgins to get the full effect ...

author: coppercone2
author_rank: Super Contributor
timestamp: March 02, 2025, 03:05:40 am
content: in a solution that is 120g/lliter of 75% NaOH and 25% Sodium Chlorite flakesI put a clean penny, and a scrap cutting of bronze.I want to see if its active at room temp, it does not appear to be (or at least its slow as hell). I will put it on a hot plate later

author: coppercone2
author_rank: Super Contributor
timestamp: March 02, 2025, 04:22:47 am
content: the bronze looks black, the copper penny looks unaffected after an hour or so soak.I put it in a double boiler setup, and the penny became quite black. It does work, it does not appear to rub off either. I would say 10 minutes to get a drastic change in color.I think I can believe that this treatment can infact help copper bond, especially because its formed on clean copper in what is essentially a powerful degreaser, so long its washed with clean water and dried well.

author: coppercone2
author_rank: Super Contributor
timestamp: March 02, 2025, 05:01:11 am
content: These were just degreased very haphazardly with dish soap , and taken from a dirty coin store, but none the less the effect is impressiveThere is a kind of textured blackness on top that can be scratched off easily to reveal a smoother blackness. Reminds me of improperly electroplated stuff ("burned")The solution turned blue, the fun part is going to be to try to repair the coinage.

author: coppercone2
author_rank: Super Contributor
timestamp: March 02, 2025, 08:13:51 am
content: I soaked one of them in vinegar for an hour, and after that treatment the stuff was rubbing off on my hands slightly, and when I rubbed it gently a worn kitchen brillo sponge, it basically restored itself to a darker looking copper coin. More bronze like.I wonder if any kind of gentle post cleaning after the blackening treatment is going to help, but I am thinking its more along the lines of monitoring it while it was blackening (I left it in there way longer then necessary to see what would happen). I think that it might build up a little, and then get 'unstable' like most things do with metal and chemicals, that is you have a 'strike' phase (where rust comes off, plating comes on, starts to change color, depending on process), then a growth phase, and then the ugly phase where it starts getting uneven), and generally 'taming' that ugly phase takes great effort and process changes.

author: jpanhalt
author_rank: Super Contributor
timestamp: March 02, 2025, 11:19:01 am
content: Etching one surface would be quite easy and probably give good adhesion too.

author: coppercone2
author_rank: Super Contributor
timestamp: March 02, 2025, 12:34:37 pm
content: I would feel alot better about etching the copper then this oxide thing, particularly because it would be easier and there would be no oxide shit touching my precious conductorsThis does not look fun for anything larger then the amount you need for a small coin (I made up 20mL).Handling wise, it looks like if you 'burn' a plating process, its about as strong and occurs at a much lower temperature with more pleasant reagents BTW, I think that 'burned' plating (too high voltage) is a more then reasonable alternative if you want this for low visibility purposes in a optics thing. Using electricity is always preferable and more intelligent then increasing bath temperature IMO, that's why I wanted to know if it works at room temperature (which it does on bronze, you only need it hotter for copper)I always get a feeling I am being primitive when I see a similar process (but more mild thanks to the use of electricity) is available, kind of like TIG vs acetylene, its so much less heat and civilized to use electricity.I am thinking maybe they specify chemical methods because of ease of implementation on their big assembly line, and there is no good reason not to use electrochemical methods, unless the 'conveyor belt' is an obstacle, which it never is for prototyping, so we end up getting industrial information that is just not really appropriate for small scale use and it ends up being absurd.but if copper etchant does increase bond performance similarly, then this whole process is pointless, and it should be better for RF things related to IMD, since at least your losing the oxides, the underside should not be ghastly black

author: jpanhalt
author_rank: Super Contributor
timestamp: March 02, 2025, 01:10:41 pm
content: I suspect there is a lot of information on electro etching copper. Here's just one from years ago:http://chemelec.com/Projects/Etching/Etching.htmIn my experience, limited to chemical etching, the etched surface becomes an even, dull, light-salmon color compared to smooth milled or electroplated copper.

author: coppercone2
author_rank: Super Contributor
timestamp: March 02, 2025, 09:01:15 pm
content: I noticed that 'unique' color when etching boards. I guess it tarnishes very quickly, because when its in a FeCl3 bath , if you hold it close to the surface, it has a much more pink color. I am guessing that this is like microscopically uneven copper that becomes basically 'highly reactive' with oxygen... it might get a substantial coating of oxide right when its pulled from the bathAs for electroetching, I guess that is a win, but already electroless FeCl3 etching is a win compared to this chlorite process, which involves 10% caustic @ 95C. I thought about that and got the big safety goggles even though it was only a ounce in a wide double boiler, it will be most unpleasant if you get that on your body. The composition is remarkably similar to chlorox tile cleaner, just more concentrated and hot.I assume electric etching solution will be edible in comparison to the above twoThat's a trend I noticed, the more power you have (and voltage), the more dilute and harmless the solution becomes. For instance in electro-plasma-polishing, you have a meager 3% ammonium chloride solution, and the danger is shifted to the power supply, which is gonna be like 20 amps @ 300V. In that case, dealing with harsh chemicals is definitely much safer then that process, but I think you can find a optimal middle ground for some things...Maybe bases are just a pet peeve of mine, i feel much more comfortable around acids, but they both get a little scary when hot or activated (i.e. piranah). Thankfully corporate beat me into submission over the years about eye and hand safety lol, I could be in my house washing dishes and get panic about being written up for not wearing goggles... micro flashbacks. I get random urges to put on goggles when I am in the hardware store too, sometimes.

author: jpanhalt
author_rank: Super Contributor
timestamp: March 02, 2025, 09:59:09 pm
content: Of course, you want to rinse well, perhaps even "passivate" with sodium acetate to neutralize residual acidic stuff, then dry and glue (e.g., prepeg FR4 or compatible epoxy to roughened FR4). It's a very fresh surface, and I have no idea how long it stays like that in air. I suspect the same goes for the thin, adherent black oxide surface one sees when peeling the copper from a regular PCB.

author: coppercone2
author_rank: Super Contributor
timestamp: March 03, 2025, 07:19:24 am
content: Why do you use sodium acetate as a neutralizer ?is the idea that ferric chloride might be attached to the PCB surface and that reacting it with sodium acetate makes iron acetate which I believe is highly soluble (but so is FeCl3). But I thought maybe there is some 'sticking' that makes it hard to rinse off, but the sodium acetate kinda attracts it off the surface?Like if there is some amount in a crevice, where its not really drawn to the rinse water, the acetate maybe flushes it out of there because of... something like a chemical migration potential to a reaction?That is maybe related to the problem with using HCl for rust removal, cleaning or flux, because it somehow bonds to the surface (even though conceptually you would think it rinses right off?)Is this some general rule of cleaning surfaces/surface chemistry, that is they are cleaner if you force a reaction (so long its soluble) then it is if you just rinse it? More then just osmosis ?Or is there strict rules, like the solubility of the product must be higher then the solubility of the target molecules? Something like a nanoscopic? 'draft' is formed ?FeCl3 is a really heavy molecule too. Something to do with vanderwalls forces that makes it sticky ? NaCl is much less heavy, IDK about iron acetate, it makes me think of like a blimp (big light organic chain with a heavy payload, where the fecl3 is a armored bathyscaph in comparison, the acetate seems like a flotation device in comparison)?

author: 5U4GB
author_rank: Super Contributor
timestamp: March 03, 2025, 08:27:10 am
content: Quote from: Benta on February 24, 2025, 01:21:39 amOne fix for your flowchart to prevent a hang on step four:Fourth (subpart a), if you're not married then place a borrowed wife in your house, then wait for her to leave.

author: coppercone2
author_rank: Super Contributor
timestamp: March 10, 2025, 02:05:52 am
content: I was thinking another idea, so we can get black aluminum anodized dye heatsinks to have slightly better thermal performance because of emissivity.How about black copper oxide PCB heat sinks. So the idea is instead of putting a PCB-green coat on the heat sink, you leave it bare and oxide it. Given that PCB heat sinks kinda suck, maybe i would improve it a little bit? I think it should have better thermal performance then pcb paint.

author: jpanhalt
author_rank: Super Contributor
timestamp: March 10, 2025, 04:53:47 am
content: Isn't radiative transfer a lot less than convective transfer on Earth?

author: coppercone2
author_rank: Super Contributor
timestamp: March 10, 2025, 05:03:11 am
content: I don't really know how it works but its documented on this forum and else where.If its just dye it must be doing something.I did however wonder about some kind of nanotexturing like that IR source I found, and possibly what the roughness from black oxide (chlorite type) and forced air would dohttps://www.mouser.com/pdfDocs/Ohmite_Heatsink_Guide.pdfApparently the big change for noctua's CPU coolers is going to be some kind of black coating in the new NH15 cooler that is upcoming too.Ohmite is saying with forced air it does not matter, but the results of what people say is all over the place. I thought that testing it with a TO220 resistor, that is SOLDERED to a square of copper with different treatments might be a OK test if you measure power input in watts. like a good reidon resistor and 2x 34401A to measure voltage/currentI saw the complete math you would need for this to really calculate radiation and it looked insane (thermal engineer explained books, it was pages of surface integrals and other shit iirc) and testing this is actually easy, you can even weigh the heat sinks on a miligram scale to be sure its not a big difference in copper'and intuitively something tells me if its rough, and your blowing air on it, maybe it might be better. Its like chalk. I thought it might be like chaotic microchannel type things happening thereAnd its even more interesting because the package temp of some of those parts is pretty high, compared to a CPU. I found formulas for blacking silver too.. that is interesting for some kind of ceramic hybrid heat sink thing (silver sulfide or telluride). Not sure what the point would be but the playing field changes when you have a ceramic substrate], at least its something to think about. Low cost down hole boring equipment?https://www.eevblog.com/forum/projects/the-performance-of-a-heatsink-with-a-black-surface/This seems to be one of those things that has people that know equations arguing with each other and arguing with the data making it murky and interesting to test