Poor man's hardware store version of PCB snot? - Page 1
Forum section: electronics / beginners

author: george graves
author_rank: Super Contributor
timestamp: April 10, 2013, 12:00:28 pm
content: I know this was discussed briefly on this forum, but there was not real conclusion.What's a good hardware store, DIY version of the stuff you find on PCB to keep large part from having vibration problems?Some say silicone....others say you need acid free stuff. (really? how acidic could it be to eat through a capacitor?!?!?!?)I was thinking of more real work solutions - not "YOU HAVE TO BUY THIS CAUSE IT"S THE BEST" thing.What's a 20-30 year solution that is cheap and easy to get? I'm mostly thinking of things like locking trim pots in place, and the large TH cap.

author: 8086
author_rank: Super Contributor
timestamp: April 10, 2013, 12:12:51 pm
content: Hot glue maybe?

author: Simon
author_rank: Unknown
timestamp: April 10, 2013, 12:13:03 pm
content: Candle wax !

author: george graves
author_rank: Super Contributor
timestamp: April 10, 2013, 12:19:52 pm
content: Quote from: 8086 on April 10, 2013, 12:12:51 pmKinda low temp - no?Quote from: Simon on April 10, 2013, 12:13:03 pmI would have accepted bubble gum as a funny answer. But no.

author: digsys
author_rank: Unknown
timestamp: April 10, 2013, 12:21:19 pm
content: Locking trimpots - I use RED finger-nail polish, Large caps - Hot melt glue. I've got stuff out there for 30+ yrs

author: Simon
author_rank: Unknown
timestamp: April 10, 2013, 12:22:06 pm
content: ever opened an old radio ? tell that is not dissimilar to wax which is easily found in candles. If your running a contest, we give up

author: David_AVD
author_rank: Super Contributor
timestamp: April 10, 2013, 12:35:37 pm
content: The stuff I see most often around big components is like a white silicone caulk. You can see where a small "tail" is left at the point where the nozzle was removed. Maybe a standard neutral cure type is used?For trim pots, etc you can buy medium viscosity "paint on" liquids. Years ago I pinched my wife's unwanted nail polish to put on tape head alignment screws to stop them vibrating loose.

author: fcb
author_rank: Super Contributor
timestamp: April 10, 2013, 01:22:32 pm
content: Dow Corning 732, not cheap but PROVEN.

author: robrenz
author_rank: Super Contributor
timestamp: April 10, 2013, 02:02:44 pm
content: DIY version silicone.From the GE site:GE Silicone II* caulk is what's called a "neutral cure" silicone, which means no acids are released during the curing process (as there are in GE Silicone I*). This enables GE Silicone II* to adhere to a broader range of substrates such as plastics, concrete, and metals. Also, the odor of a neutral cure silicone such as GE Silicone II* is much less offensive than an acid or acetoxy cure silicone such as GE Silicone I*.This is very inexpensive at you local DIY store. Silicone is tough to beat as an long term adhesive and its resiliency enables it to endure shock loadings better than just about any adhesive.Hot glue would not be my recomendation for anything long term. Its adhesion to metal is not great and who knows what the quality or type of hot glue formulation you are getting these days since now it may come from who knows where.Try this test for yourself: Take 2 junk capacitors and clean the tops off with IPA and clean two spots on a piece of junk circuit board. Glue one on with hot glue and one on with the silicone. let it cure a couple ofdays(one negative of Silicone) and try breaking them off the board. The results will speak for themselves.I agree with the nail polish for securing the pot settings. The resiliency of silicone will not secure them as solidly as the nail polish. But nail polish on the head of a machine screw does not keep it from vbrating loose. There are anti vibration paint like materials that may leave a ring of "paint" around the head of a screw if applied that way. These are special formulations that are not brittle like nail polish but more tough and gummy. But the vast majority of paint on screw heads is for anti tamper use. Especially where there is an alignment or adjustment that will be affected.

author: Nirios
author_rank: Regular Contributor
timestamp: April 10, 2013, 02:23:12 pm
content: Quote from: robrenz on April 10, 2013, 02:02:44 pm+1 for the DIY silicone. If you are in the US, I've used Liquid Nails LN-207 before. Cost only $4 for a 4oz tube and says it has a shelf life of 12 months. It is also available in most big box DIY stores.

author: lgbeno
author_rank: Frequent Contributor
timestamp: April 10, 2013, 03:25:30 pm
content: We used hot melt before in a pinch and I have seem commercial psus with it. It connects this rigidly so doesn't have the dampening effect that silicone does. I this either are good poor mans alternate.

author: blewisjr
author_rank: Frequent Contributor
timestamp: April 10, 2013, 05:46:17 pm
content: Quote from: Nirios on April 10, 2013, 02:23:12 pmliquidnails omg you would break the PCB in half before the component comes free good stuff that is.

author: SeanB
author_rank: Super Contributor
timestamp: April 10, 2013, 06:22:06 pm
content: For stopping microphonic effects from vibration use beeswax, that is often applied for both damping and environmental protection. For the holding down of components use the neutral cure silicones, generally the ones marked as safe for use on brass or copper items. If you want the best use a 2 part flexible epoxy like Pratley Wondafix, which is both flexible and incredibly tough when cured. It basically cures to a rubber that is firmly bonded to the surfaces. If you are prepared to have a little blooming use a thick gap filling superglue.

author: David_AVD
author_rank: Super Contributor
timestamp: April 10, 2013, 09:36:08 pm
content: Quote from: robrenz on April 10, 2013, 02:02:44 pmThe polish I used at the time was not super brittle when dry, so seemed to work very well at stopping the azimuth screws from wandering. That was even on the auto reverse decks where the head spins around at the end of the tape side.

author: pickle9000
author_rank: Super Contributor
timestamp: April 10, 2013, 09:57:57 pm
content: I agree with Robrenz, I have used GE Silicone II for years with no issues. I always use clear although colours may be OK I just preferred to have as few additives as possible.

author: nanofrog
author_rank: Super Contributor
timestamp: April 11, 2013, 03:50:13 am
content: There are good quality hot glues designed for electronics (3M makes this sort of stuff), but you usually have to order it through a supplier such as digikey. Some is also hygroscopic, so has to be stored in an air tight container.3M's Hot Melt Adhesive page for electronics:http://products3.3m.com/catalog/ca/en001/electronics_mfg/electronics/node_NN81LX9TS1be/root_VJ3G0N3T7Ngv/vroot_26VR525FJ8ge/gvel_K7KGGBLQPNgl/theme_ca_en_electronics_3_0/command_AbcPageHandler/output_html3M Electronics Assembly SolutionsProduct Selection Guide (.pdf @ 4.7MB; covers everything they offer for electronics manufacturing):http://multimedia.3m.com/mws/mediawebserver?mwsId=SSSSSufSevTsZxtUmY_GNxmGevUqevTSevTSevTSeSSSSSS--&fn=ElecAssmbly_6001292_lowres.pdf

author: codeboy2k
author_rank: Super Contributor
timestamp: April 11, 2013, 06:26:35 am
content: non-sanded white tile grout.I am sure this is what the chinese manufacturers' use. That stuff is hard like a rock and has to be cracked off. It's not rubbery like the silicone many people suggest here, although silicon is probably easiest to apply from its tube.Also, +1 for Liquid Nails. That's great, strong stuff...

author: Stonent
author_rank: Super Contributor
timestamp: April 12, 2013, 01:29:04 am
content: Quote from: Nirios on April 10, 2013, 02:23:12 pmI was going to say the same thing, not because of experience, just the white gunk on boards looked exactly like liquid nails.

author: smashedProton
author_rank: Frequent Contributor
timestamp: April 12, 2013, 05:00:34 am
content: Silicone can also work ad thermal goop in a pinch. Its very useful stuff. Just don't grind it into the carpet!

author: peps1
author_rank: Regular Contributor
timestamp: April 12, 2013, 02:28:45 pm
content: Its all about the Wax.....been used in audio equipment for decades, and is really handy for guys like me who love vintage audio gear as its so easy to rework.still used today on guitar pickups

author: ConKbot
author_rank: Super Contributor
timestamp: April 13, 2013, 04:43:47 pm
content: Quote from: george graves on April 10, 2013, 12:00:28 pmAcid cure RTV silicone makes quite a bit of acetic acid (vinegar). A relay was being used on a safety system that was being used to disconnect 2 lines and short them to ground. The equipment operator would use a DMM with banana plugs to make sure they were shorted solidly, multiple times per day. One day the reading crept up to 0.5 ohms instead of the usual 0.1 ohms. The fix? clean the exposed brass relay contacts because the acetic acid fumes from the acid-cure RTV sealing up a couple connectors had tarnished it in a matter of a few weeks, and there was never any wetting current on that pair of contacts.So yes, it is an issue if you have exposed copper/copper alloys anywhere near by.

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 13, 2013, 04:54:15 pm
content: I really like Amazing Goop. It sticks really well and is quite hard to remove. I also use super glue for small parts (like reinforcing a wire soldered to a SMD component) and hot glue where strength is not required.

author: JackOfVA
author_rank: Unknown
timestamp: April 13, 2013, 05:37:42 pm
content: Dow Corning 732 is good stuff, no doubt.Here's a question, however, that I don't have a good answer for. I use 732 or a similar product once or twice a week to anchor a ferrite toroid core or a powdered iron core to a PCB. That job takes maybe a minute at most. However, after applying the adhesive, it then takes me 5 or 10 minutes to completely clean the nozzle so that the next time it isn't plugged up.Am I wasting time cleaning the nozzle after each use or should I just let it set up and push it out with a stiff wire in a week or two when the next application is due? My experience has been allowing it to set up is only marginally easier than cleaning after each use but perhaps I'm not going about this correctly.Another product I use for some parts are "glue dots" -- small diameter (0.5 inch / 12mm) thin patches of adhesive. Peal one off the sheet and put it on the PCB, warm it up with the hot air gun and then add the part to be retained. Only useful for flat parts such as binocular ferrite cores since it needs a considerable contact footprint.

author: Chet T16
author_rank: Frequent Contributor
timestamp: April 13, 2013, 05:47:34 pm
content: In work they use some type of Dow Corning silicone stuff, not sure which but its red if that helps. This is for high vibration applications so it must have proved itself!

author: SeanB
author_rank: Super Contributor
timestamp: April 13, 2013, 06:41:33 pm
content: Just buy a few tubes or 2 part flexible epoxy, and get a load of small plastic cards to mix small quantities, stirring the 2 beads together with a small HDPE paddle used to mix, apply and clean up the area. Cheap, and you only mix what you need, and the small remainder will be easy to flake off after it has cured if you choose plastics that are not going to bond with the epoxy, like HDPE, PTFE or PET. It generally adheres well to most board resins, and many other plastics, varnishes and almost any metal. As a bonus it stops ferrite cores whistling.

author: M0BSW
author_rank: Frequent Contributor
timestamp: April 13, 2013, 07:02:09 pm
content: Now I can help with this one , I have here some really old 1940's wirelesses, with candle wax on the coils & trimmers,and when I set up a trimpot on one of my CW transmitters I used some of my wife's nail varnish, red is the best as you can see where you've been,best not to tell the wife though .

author: vk6zgo
author_rank: Super Contributor
timestamp: April 14, 2013, 06:34:21 am
content: If you weren't so miserly,you would keep her current one,buy her a replacement bottle & a spare for your work.Of course,she will then know that you're using it!

author: notsob
author_rank: Frequent Contributor
timestamp: April 14, 2013, 06:42:03 am
content: One place I worked at had a few pot twidlers, instead of analysing a fault, they would play with the pots first. Really annoying when one got called to a site after them to find machines having errors due to miss alignment. So I had a collection of different colours of nail varnish of really weird colours that I used to 'lock' the pots. So I could catch the 'bastards' out.