Silicone sealant - silastic, silcoset, etc - Page 1
Forum section: electronics / general

author: bigsky
author_rank: Regular Contributor
timestamp: October 10, 2014, 11:34:26 am
content: I need to get some white silicone sealant for sticking big components down.There seems to be a lot of different types available.Can anyone suggest something, available from a UK supplier like RS, Farnell, CPC, Rapid. Is there an industry standard product?The silicone these places sell seems to be a lot dearer that the silicone sealants you get from builders merchants and DIY shops in cartridges for mastic guns. Are these unsuitable for electronics work?I've somehow managed to avoid buying this stuff over the years - pardon my ignorance.Thanks!

author: bookaboo
author_rank: Frequent Contributor
timestamp: October 10, 2014, 11:52:44 am
content: Builders silicones are corrosive to PCBs, I've seen them eat through solder mask and copper boards. Rapid had some reasonable priced compounds under the "servisol" brand though it's a while since I used them so others may have good suggestions.

author: klr5205
author_rank: Regular Contributor
timestamp: October 10, 2014, 11:57:17 am
content: My company has gotten a lot of use out of RTV 162 over the years.We mostly use it in industrial applications for doing just what you describe - keeping electrolytics and other large components in place in high vibration environments.

author: BradC
author_rank: Super Contributor
timestamp: October 10, 2014, 02:42:24 pm
content: Check the bathroom section of your local hardware. You want "Neutral Cure" silicone sealant. The common stuff emits Acetic Acid as it cures and as pointed out above will wreck anything it is close to. Neutral Cure does not. Simple and cheap, just read the label.Most silicone I've seen on PCB's looks like 2 pot where it'd be squeezed and mixed in a mechanical nozzle and squirted on the board. It'd then be anywhere from 30 seconds to 5 minutes until its fully cured. You need the machine to do that stuff. Neutral cure bathroom sealant is what the rest of us use.I started to use hot melt glue a while back for sticking stuff down. Does the job faster.

author: nanofrog
author_rank: Super Contributor
timestamp: October 10, 2014, 03:16:16 pm
content: Neutral cure comes in 2 varieties; alkoxy and oxime. Both can be used for electronics, but it'sreally only the alkoxy that you want to be using, as it won't cause any damage (alkoxy = moisture cure, releases methanol). Oxime *can* be used, but with caution (corrodes copper). Releases ketones, such as acetone.GE's Silicone II is an example of an alkoxy cure that's widely available on the shelves (US at any rate).Dug around their site, andDow Corning 796 Silicone Sealantis suitable, and is available in the EU & UK via building supply shops (alkoxy & methoxy cure listed for it).

author: German_EE
author_rank: Super Contributor
timestamp: October 10, 2014, 03:34:43 pm
content: As suggested, check the bathroom section of your local hardware store but then you need to use your nose. Some silicone sealant contains acetic acid and if you smell the end of the tube it's a similar odour to vinegar, don't buy this stuff! I have had good results with a product called 'No Nails' which is designed as a glue but works like a silicone sealant.

author: aroby
author_rank: Regular Contributor
timestamp: October 10, 2014, 03:49:44 pm
content: Quote from: German_EE on October 10, 2014, 03:34:43 pmIf the end of the tube isn't sealed, don't buy it! You can't smell the acetic acid from a sealed tube.