Silicone Sealer
- Thread starter John O
- Start date
The ordinary silicone seal/caulk contains acetic acid and will cause corrosion. There are "electronics compatible" formulas out there...but I can't give you a link at the moment. 
ok: http://www.maplin.co.uk/search?criteria=Silicone+Adhesive+Sealant
And, unless heat is an issue, I like hot-melt glue.
Ken
ok: http://www.maplin.co.uk/search?criteria=Silicone+Adhesive+Sealant
And, unless heat is an issue, I like hot-melt glue.
Ken
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Thanks for the reply. Yes, I was thinking the ordinary stuff smells a bit acidic.
A friend suggested hot melt glue. It would only be holding down a couple of 47uf 16v capacitors so I wouldn't expect heat to be a problem - not that I've ever used hot glue so I've no idea how hot it is!
As I only need a couple of blobs, it'll be more cost-effective to get my mate to demonstrate its use
Thanks,
John.
A friend suggested hot melt glue. It would only be holding down a couple of 47uf 16v capacitors so I wouldn't expect heat to be a problem - not that I've ever used hot glue so I've no idea how hot it is!
As I only need a couple of blobs, it'll be more cost-effective to get my mate to demonstrate its use
Thanks,
John.
I've used latex caulking to good effect, and hot melt adhesive at times, as well as the (acetic acid) silicone without any noticeable problems.
But then I've been using WD-40 to lubricate and treat noisy potentiometers for 30 years without problems, in spite of the dire consequences promised me on some newsgroups.
Usually I'm more concerned with the flammability of the compound - so I subject it to a propane torch - silicone and latex caulk are both good for high temperatures and don't burn readily, hot melt adhesive burns (and softens at some relatively mild temperatures).
But then I've been using WD-40 to lubricate and treat noisy potentiometers for 30 years without problems, in spite of the dire consequences promised me on some newsgroups.
Usually I'm more concerned with the flammability of the compound - so I subject it to a propane torch - silicone and latex caulk are both good for high temperatures and don't burn readily, hot melt adhesive burns (and softens at some relatively mild temperatures).
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Andrew Cowan
Senior Member
I've only ever used the hot melt type - it's ideal for gluing parts to boards.Wikipedia said:
I've used double-sided sticky pads to hold down larger electroytics and other components and that seems to work well.
Whatever is used, if not 'the recommended product', will probably have some issues, corrosion, flammability - the later not something I'd personally considered with sticky pads ! Not consciously at least; it probably came under the subconscious risk assessment catch-all of "if it's on fire then there are probably bigger things to worry about"
That's no real excuse against doing a full risk assessment of all failure modes and considering the consequences of all eventualities. Where there's an obvious potental for something getting hot or being affected by how it's used it is important to consider that.
Whatever is used, if not 'the recommended product', will probably have some issues, corrosion, flammability - the later not something I'd personally considered with sticky pads ! Not consciously at least; it probably came under the subconscious risk assessment catch-all of "if it's on fire then there are probably bigger things to worry about"
That's no real excuse against doing a full risk assessment of all failure modes and considering the consequences of all eventualities. Where there's an obvious potental for something getting hot or being affected by how it's used it is important to consider that.
Andrew Cowan
Senior Member
Although not suitable for holding capacitors to boards, those self adhesive velcro pads are also really under-rated - I find them brilliant for securing batteries, modules, boards - even the GPS in my robot is held on with them!
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I've had great success with Velcro too.
In fact there are quite a few variants on Velcro (hook/loop design and adhesive) , but do watch out for self-adhesive failure at certain temperatures and in prolonged damp.
To stop something vibrating you need something rigid or not very compliant i.e. fairly firm.
Adhesives usually include epoxy , acrylic and thermal.
I've never had problems with silicone which liberate acetic acid during the cure , though I would never resommend them as there are so many different types. And there are non-acetic silicones around and (expensive) 2-pack too. Check out all the varities of potting compounds. Some components are more sensitive than others , so I'd always take the manufacturer's advice rather than the Forum.
And note the cure/dry speed. Some are blooming slow. Some are blooming expensive.
There are a zillion adhesives on the market so have a look around.
My 'favourite' from the strength / speed perspective is:
http://cpc.farnell.com/deluxe/ad-23/super-crylic-adhesive-kit/dp/SA00784?Ntt=super+crylic
When used correctly in the right place it is amazing and a reasonable shelf-life too.
What's your favourite?
In fact there are quite a few variants on Velcro (hook/loop design and adhesive) , but do watch out for self-adhesive failure at certain temperatures and in prolonged damp.
To stop something vibrating you need something rigid or not very compliant i.e. fairly firm.
Adhesives usually include epoxy , acrylic and thermal.
I've never had problems with silicone which liberate acetic acid during the cure , though I would never resommend them as there are so many different types. And there are non-acetic silicones around and (expensive) 2-pack too. Check out all the varities of potting compounds. Some components are more sensitive than others , so I'd always take the manufacturer's advice rather than the Forum.
And note the cure/dry speed. Some are blooming slow. Some are blooming expensive.
There are a zillion adhesives on the market so have a look around.
My 'favourite' from the strength / speed perspective is:
http://cpc.farnell.com/deluxe/ad-23/super-crylic-adhesive-kit/dp/SA00784?Ntt=super+crylic
When used correctly in the right place it is amazing and a reasonable shelf-life too.
What's your favourite?
Double sided sticky foam tape
I have used double sided sticky foam tape for a while. I got three rolls 2m long by 1.8cm wide from the local Pound Shop for the standard Pound. It doesnt require any applicators or anything and sticks like h*ll. It probably wont work with things that heat up or weigh a lot, but at £1 for maybe a year or so's supply its O.K.
Clockwork
I have used double sided sticky foam tape for a while. I got three rolls 2m long by 1.8cm wide from the local Pound Shop for the standard Pound. It doesnt require any applicators or anything and sticks like h*ll. It probably wont work with things that heat up or weigh a lot, but at £1 for maybe a year or so's supply its O.K.
Clockwork
Andrew Cowan
Senior Member
Interestingly, I bought a load of double sided foam pads a few years ago.
The rectangular pads, in their old age, have dried up and have no stick.
The rolls, in their old age have become amazingly sticky, and won't come off anything.
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The rectangular pads, in their old age, have dried up and have no stick.
The rolls, in their old age have become amazingly sticky, and won't come off anything
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Minifig666
Senior Member
It would be brilliant, just rub it on before it went throung through the reflow oven. It would be an eggstremely cheap alternative.
Still does, it is one of the classic adhesives for gold leaf gilding.egg whites.... worked in the middle ages and still does
They also invented the tampon - originally a tight bundle of bound rags used to tamp the gold leaf into the protein adhesive.
They are a pretty good burnishing tool too where you want to apply a little abrasive to shine a part. (my wife is past menopause so I have a stock of the things) Sanitary pads? Excellent wound dressings, and way cheaper than anything made for the purpose - just a little masking tape to hold it in place. (she left me those too)
StigOfTheDump
Senior Member
We used to use silicone sealant to waterproof connectors on earth moving equipment. One day I couldn't get any and used some other type of window sealant. Nothing worked. It turned out that the stuff I had used was conductive.
Andrew Cowan
Senior Member
Really? I've bought 'low melt' glue sticks before to use on heat sensitive parts.
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fritz42_male
Senior Member
Hot melt glue here - however I use the low temp 'fabric' version. As well as melting at a lower temperature, it seems more bouncy so works well in vibration prone environments. I also find it sticks better than the high temp version.
Michael 2727
Senior Member
It all depends on how hot your components may or may not get.
Capacitor temp ratings will sometimes give you a clue e.g. 85C or 105C.
Many power supply caps are rated at 105C because they can get quite hot, in
many cases caused by the component next to them on the PCB.
Silicone netural or acetic cure are usually rated to well over 200C Deg
temp, some over 300C. And usually stays where it is applied without moving
Rubber cement is/was another commonly used product, it can be slow drying
and usually runs downhill from where it was applied reasonably heat reatistant
when dried.
I hate them both, makes repairs on SMPS and LCDs that much harder.
Capacitor temp ratings will sometimes give you a clue e.g. 85C or 105C.
Many power supply caps are rated at 105C because they can get quite hot, in
many cases caused by the component next to them on the PCB.
Silicone netural or acetic cure are usually rated to well over 200C Deg
temp, some over 300C. And usually stays where it is applied without moving
Rubber cement is/was another commonly used product, it can be slow drying
and usually runs downhill from where it was applied
reasonably heat reatistantwhen dried.
I hate them both, makes repairs on SMPS and LCDs that much harder.
What I should of said is that the general purpose glue sticks for the hot melt guns also melt with the low temp guns