• Please note that Audiokarma will be offline briefly for updates early on Monday morning, September 28th.

Capacitor glue?

N

ncgrant

New Member
I just finished replacing the caps on the crossover of my SP-3500s. All the old caps were glued down like mad. While I suppose the new ones don't absolutely need to be glued down, it seems like the right thing to do. I'd like to use hot glue as it is fast and easy. Additionally a few of the gaps between the board and the cap are larger now (since the replacement caps were so much larger I couldn't fit them all down tight against the board side-by-side) and hot glue is thick enough it should easily span these gaps.

The obvious question this raises that I don't know the answer to is, will the temperature of the hot glue damage (or in any other way adversely effect) the new caps? With $40 invested I certainly don't want to do anything to harm them. If the temp of the hot glue is detrimental, does anyone have any suggestions for another glue that works well for this purpose?

Thanks in advance!
 
Register to hide this ad
Great Idea!

Sounds reasonable to me. Just do not get any hot glue on the pins of the capacitor as the hot glue may be conductive over time. Use it sparingly :yes:.

Ardvaark
:music:
 
Last edited:
Ardvaark said:
Sounds reasonable to me. Just do not get any hot glue on the pins of the capacitor as the hot glue may be conductive. Use it sparingly :yes:.

Ardvaark
:music:
Click to expand...
:scratch2:
That brings up a good idea, you could test the glue for conductivity before using it on your expensive equipment:thmbsp:...or...It Could all end in :tears:
 
I never re-glue.:no: I've scraped to much of the stuff off, and some of it is actually corrosive (Sansui being one).:thumbsdn:
 
Double sided foam tape. works great. damps vibration and it's not permanent if you want to change values.
You won't be in the same fix again.
 
Large electrolytic capacitors can vibrate at low frquency and cause mechanical damage. They are often mechanically bonded to the circuit board with adhesive to prevent this. You have to be careful about adhesive selection however - some adhesives emit corrosive gas during the curing process and the gas can damage :tears: susceptible components (e.g. the aluminum in the cap). There is also the problem of conductivity. Forget the hot glue and tape (you can't tape "snap-in" types anyway) - you want a "neutral cure" or "electronics grade" adhesive such as RTV162 (which I typically use). Not all RTV is "electronics grade" so be careful to select this type. Capacitor manufacturers sometimes recommend specific adhesives in their datasheets or technical publications.

HTH,
klancf51
 
Last edited:
capacitor glue

A small bead of Liquid nail around the base works fine and can be pulled off if necessary. THere should be no need of any adhesive on or around the pins. The adhesive should be only around the perimeter of the can.
 
Detailman said:
Double sided foam tape. works great. damps vibration and it's not permanent if you want to change values.
You won't be in the same fix again.
Click to expand...



Ive used double side tape as a base, particularily on multiple layers (as in building height/distance) I like to go around the double sided tape with a slight amount of RTV overlapping the foam tape to just contact the board and the cap slightly.
Just helps me feel better about the fact that contact adhesives ALWAYS dry out as they age and with constant vibration, I like to hedge my bets.
Tal
 
hot glue worked well on my Dayton crossover caps, the glue isn't too hot and it cools very fast anyways.
 
qboneus said:
Ive used double side tape as a base, particularily on multiple layers (as in building height/distance) I like to go around the double sided tape with a slight amount of RTV overlapping the foam tape to just contact the board and the cap slightly.
Just helps me feel better about the fact that contact adhesives ALWAYS dry out as they age and with constant vibration, I like to hedge my bets.
Tal
Click to expand...

10-4 on hedging bets.
Thanks for the heads up. Sounds like easy insurance and extra damping.
 
Be careful!!

One last time: many adhesives produce corrosive compounds during the curing process and these gases can be corrosive. For instance, common RTV's out-gas ammonia during cure - ammonia plus water in the air produces ammonium hydroxide, an aggressive alkali. Other types of RTV depend on strong acetic acid to work. Liquid nails??? WTF - most construction adhesives are known to de-silver mirrors. Liquid Nails actually makes a special "Mirrors Adhesive" for just this reason. There is some good information on this forum but well-intentioned misinformation also. Use what I recommeded and avoid this well-known problem.
 
I am using RTV in the generic type of term as a general identifier of a type of product, not to attempt to disqualify or contradict your post about using the 'proper' chemical adhesives.
there are situations where it impractical to make a 1/4" deep bead of the proper fixative, wait for it to dry and then commence assembly, Instead you can build a small bridge that will close this gap using ds tape.

I've used electronics RTV or a product called "the right stuff" from an auto parts store it has been more than satisfactory to suit my needs and I am talking about using a minute amount as supplementary/additional support.

Tal
 
Hot melt glue does not hold well.

RTV's sometimes contain corrosive acetic acid.

Double sided tape dries out and does not hold up well over the long haul.

What I have found REALLY does a good job, on caps as well as heavy inductors, for crossovers, stabilizing large filter caps in power supplies, other general gluing and repair, is a class of adhesives known as SBR adhesives. This stands for Styrene Butadyene Rubber.

There are several viscosities available, and each has its use.

The thinnest is Seal All, automotives and hardware, red, yellow, and black tube. Viscosity about like plastic model cement (Pactra and Testors). It is think dries clear and flexible.

attachment.php


Medium viscosity, Aleene's Platinum Bond 7800. White tube. Craft and hobby stores. Bridges gaps better than Seal All, good working time, glues dissimilar materials very well.

attachment.php


Thickest, this stuff REALLY bridges gaps, gels quite fast, E6000. Gray tube with red, black, white lettering. Smear some on a large cap or inductor, some where you want it to stick, let it sit up for 3-5 minutes to let excess solvents evaporate, mash it together, and it is not going anywhere. Hardware and craft/hobby stores.

attachment.php


As you can see, I use it for some instrument repair and custom work.

7800 and E6000 are better for building xovers.
 
My answer is none of the above. The best product currently produced for gluing down caps, etc. is Goop also known as Shoe Goo. I use an outdoor variety because it has an added UV inhibitor.

This stuff has enormous strength but can be undone without damage by pulling with an even force and waiting for the bond to come undone, patience is the key. Comes off like a big booger. A poor description of how it works but I have never ruined anything with it, despite its enormous bond strength. It is the only adhesive I have seen that you can remove all of it without a trace, including RTV.
 
OK guys chemistry aside

Yes each adhesive has different qualities and off gasses, but some of these responses seem a tad too "chicken little says the sky is falling".

Liquid nail is NOT a mirror mastic. Mirror mastic is a viscous petroleum based mixture resembling tar.

RTV and other silicone based adhesives do off gas during curing. They are used SAFELY with most any plastic, rubber, painted surface, fiberglass etc.

The body of the cap is hermetically sealed to contain the electrolytic chemical s and to prevent the influx or air - the most damaging "gas" to the capacitor. If it effectively seals OUT air, any other non inert gaseous ingredient has little chance of penetrating.

If the solvent ingredients in the adhesives mentioned above were dangerous to the capacitor, imagine the dangers posed to humans in merely handling them.

The shrink wrap on capacitors is a plastic tube that is heated under hot air during manufacturing to insulate and provide a base for the label in the cap. It is NOT a structural component of the cap in any way.

NONE of the fave adhesives mentioned will in any way compromise this shrink wrap material the containment vessel or the electrolytic assembly

I personally like Liquid Nail as it adheres to phenolic et al substrates very well, has a low odor, tacks up fast, fills gaps, and comes in small easy to use and store squeeze tubes. It is also cheap.

We are adding additional mounting security and vibration damping to a very lightweight passive component.

We are NOT securing heat absorbing tiles to the Shuttle.
 
Thank you for weighing in on this Paul C. Let's see: you propose using a craft's ahesive, Aleene's Platinum Bond 7800, in an electronics application to directly bond electrolytic capacitors to the circuit board. You even gave us a picture so we won't mistakenly get the wrong thing! Why spend money on RTV162 when Aleene's Platinum Bond 7800 is just as good? But you neglected :no: to mention that Aleene's Platinum Bond 7800 happens to contain tetrachloroethylene :sigh: aka perchloroethylene (trade name: Perc); a halogenated hydrocarbon that can cause serious damage if allowed to come into contact with aluminum electrolytic capacitors. This solvent may dissolve or decompose the insulating film and reduce the insulating properties to below the permissible level. The capacitor seals may be affected and swell, and the solvent may even penetrate them. This will lead to premature component failure. But I say that since Paul C. has had such good luck with it, why be bothered with the chemistry - let's all follow along. Better yet - let's hope that the electronics industry adopts Aleene's Platinum Bond 7800 adhesive as a standard. BTW:E-6000 also contains tetrachloroethylene. Thanks again.

Thanks also to Gizmologist for backing-up Paul C.: "If the solvent ingredients in the adhesives mentioned above were dangerous to the capacitor, imagine the dangers posed to humans in merely handling them." Just imagine. How about imagining that we go to DuncanCrafts.com: How to use Platinum Bond 7800 where we read:

"Caution: Contains tetrachloroethylene. Deliberate misuse may be harmful. Warning: This product contains a chemical known to the State of California to cause cancer. Harmful if inhaled or swallowed. May cause dizziness, headache or nausea. Can cause skin and eye irritation. Exposure may cause damage to the kidneys or liver."

Oh-oh. The solvent in this adhesive is dangerous to the capacitor and humans. But "NONE of the fave adhesives mentioned will in any way compromise this shrink wrap material the containment vessel or the electrolytic assembly." Wrong again. See Elna:Technical Information

The point is this: a "best practice" for DIY posted by an electronics professional with years of experience can be dismissed by someone with hobbyist knowledge. It's up to YOU to check the facts.

Stick with RTV162 (no pun intended).


Sources:
DuncanCrafts.com: How to use Platinum Bond 7800

Cornell Dublier Application Guide, Aluminum Electrolytic Capacitors
See: Potting and Gluing, p. 2.201

EPCOS Aluminum Electrolytic Capacitors, General Technical Information
See: Section 9.5

Elna:Technical Information
See: Cautions When Using Aluminum Dielectric Capacitors
 
Correct procedure for gluing an aluminum electrolytic capacitor

Contrary to some previous posts, here are some tips for correctly gluing an aluminum electrolytic capacitor:

1) Be certain that varnishing, coating, lacquering, embedding or gluing near the capacitors’ seals are halogen free. And be sure all constituent parts including base material, thinners, binders, reacting agents, propellants and additives are halogen free, non-corrosive and acid free. A "neutral cure" or electronics grade adhesive (such as RTV162) is an acceptable adhesive.
2) If the printed circuit board has been cleaned with halogenated solvent, be sure it’s fully dry before installation of capacitors.
3) Apply the adhesive to the capacitor and mounting surface being careful to not apply adhesive to the full capacitor circumference in order to provide "breathing space" for the pressure-relief vent.
4) Be sure not to cover the capacitor’s pressure-relief vent with adhesive.
 
as I said, the sky is falling

According to the state of California EVERYTHING causes cancer. Those signs are posted on almost EVERY single store including those that do not sell anything ingestable- including clothing stores.

After 40 years working on all kinds of electronic systems- commercial and homeowner and using a multitude of adhesives and solvents, I can safely and accurately claim that I have not ingested any of them nor have I huffed any.

There are NO solvent based adhesives INCLUDING RTV that do not carry some sort of health risk if used incorrectly.

After a few thousand repair and design jobs, not one time have I had a component compromised using Liquid Nail or industrial hot glue. I do not use the white craft grade but rather the yellow industrial grade. There are many chemical formulations in hot glues but most refer to cure time, tack, and susceptibility to other ambient chemicals.

Does it not strike anyone as strange that California seems to find cancer under every rock while no other state seems capable of conducting equally accurate chemical analysis?

Emphasis is on ANALysis.

Here in SoCal, every 1.98 extension cord carries another tag (English and Spanish) as to the cancer causing compounds they MAY contain. This is NOT a UL tag but rather a tag put on for items sold ONLY in SoCal.

BTW the adhesives that hold that tag on and the Mylar the tag is made from CAUSE cancer.

Relax, have a cup of coffee and stop worrying. used in the appropriate quantities, and conditions, any of the preferred methods mentioned will work.
 
You must log in or register to reply here.
Back
Top Bottom