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eHam Forums => Elmers => Topic started by: KC2YQY on September 07, 2010, 04:59:38 PM



Title: Hot Melt
Post by: KC2YQY on September 07, 2010, 04:59:38 PM
Kinda of silly question: Is the glue from a glue gun in any way conductive? I've used it on toroid's and such, but I have never used it on components and leads. I always considered it a dielectric, but I just want to be sure before I fasten down some components. I have a bank of pots without any support tangs and I want them to not break or bend. Thanks in advance. -Bill-


Title: RE: Hot Melt
Post by: K7KBN on September 07, 2010, 05:56:07 PM
Different manufacturers will quite probably use slightly different formulae for their glues, so the easiest way to find out in a specific case is to put down a blob of the stuff, let it set up, and check it with an ohmmeter first, and if possible, with a megger also.  Most relatively new meggers have selectable output voltages.  I'd try at least 2x the voltage you expect to encounter around those pots.


Title: RE: Hot Melt
Post by: KC2YQY on September 07, 2010, 06:28:26 PM
Call me igorant, but what is a megger? I'm pretty new to radio. Thanks for the reply. -Bill-


Title: RE: Hot Melt
Post by: KG6WLS on September 07, 2010, 06:45:47 PM
Megger is just another field name, or a slang if you will, for a megohmmeter.

73


Title: RE: Hot Melt
Post by: N8CMQ on September 07, 2010, 06:49:23 PM
A megger is a high voltage megohm meter.
Another test is put it in the microwave and see if it heats up/melts.


Title: RE: Hot Melt
Post by: KE3WD on September 07, 2010, 08:17:33 PM
I've used all sorts and brands of glue sticks on electronics over the years with impunity. 

I wouldn't recommend its use on high voltage or line voltage components, but for the average solid state circuits, have at it. 




Title: RE: Hot Melt
Post by: KE4ILG on September 07, 2010, 08:36:33 PM
One item I want to add to the hot glue thread is that high percentage alcohol will remove it.  So if you want a temporary glue nothing beats hot glue.  The 80 percent rubbing alcohol is too low for very quick release of the hot glue but 90 percent works very well.  You can get de-natured alcohol at lowe's etc and it works great as a releasing agent for the hot glue. 

Also in a business I am no longer involved with I used hot glues of various temp ratings.  I'm not sure what is available but for use inside electronic temperature ratings of the hot glue  may be of interest.

73 to all, Mike ke4ilg


Title: RE: Hot Melt
Post by: KC3JV on September 07, 2010, 10:23:54 PM
I am a Chemical Engineer and will tell you that hot melt glue is Butyl Rubber of various melting points.   It has a decent dielectric dissipation factor but the best low loss plastic is Styrene, Polyethylene, Teflon (TM).

Mark Rothstein, P.E.  KC3JV


Title: RE: Hot Melt
Post by: W0BTU on September 08, 2010, 03:51:29 AM
A megger is a high voltage megohm meter.
Another test is put it in the microwave and see if it heats up/melts.


The microwave test would be the one to use, since a megger will only measure the DC resistance.

FWIW, my company has manufactured and sold thousands of products that use a type of hot melt glue for DC high voltage insulation, and it works very well when properly used, thank you.


Title: RE: Hot Melt
Post by: WA3SKN on September 08, 2010, 07:50:20 AM
Most glues are not conductive.  You can check DC resistance with an ohmmeter easily.  But for AC you want to test at the frequency you are going to be using.  This is a little harder.  The microwave test will check at 2.4 Ghz, the theory is if it is OK there it will also work at lower frequencies... usually true!
You could just mount one or two and see how they work, though.
73s.

-Mike.


Title: RE: Hot Melt
Post by: W0BTU on September 08, 2010, 07:53:58 AM
... The microwave test will check at 2.4 Ghz, the theory is if it is OK there it will also work at lower frequencies...

I agree.

Let us know what you find. I don't want melted hot glue all over the inside of MY microwave!! (just kidding).


Title: RE: Hot Melt
Post by: W8JI on September 08, 2010, 08:59:10 AM
A "microwave test" tells you how the material behaves at microwave only so far as exposure to electromagnetic fields.

It does not tell you anything especially meaningful for use at HF or lower in the presence of strong fields, about dielectric constants, about voltage breakdown, or about high leakage resistances. It is actually not much of a test at all.

From experience I can tell you traditional hot melt glue is pretty good at HF. I've used it in some stressful applications with high voltage gradients at high frequencies without incident.

73 Tom




Title: RE: Hot Melt
Post by: W0BTU on September 08, 2010, 09:27:12 AM
A "microwave test" tells you how the material behaves at microwave only so far as exposure to electromagnetic fields.

It does not tell you anything especially meaningful for use at HF or lower in the presence of strong fields, about dielectric constants, about voltage breakdown, or about high leakage resistances. It is actually not much of a test at all.

That's a given. But it's certainly better than my tests at DC. That's the point I was making.

Quote
From experience I can tell you traditional hot melt glue is pretty good at HF. I've used it in some stressful applications with high voltage gradients at high frequencies without incident.

73 Tom

I didn't know that, and I'm sure your experience will come in handy here sometime. Thanks for your insight.