Electronics > Beginners

OTC "Silasitc"?

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BurningTantalum:
Just to clear this up: Dave is Australian, and the term 'Silastic' is, as detailed, a trade name of Dow Corning, but is used in Australia as a generic term for any sealant goop (Viz: Hoover, Doona, Graviner etc.)
BT

graeme.c.payne:
My memory is that "Silastic" was (is?) an early brand name for some silicone adhesives. (USA)

For electronics, silicones are widely used for hording parts in place, vibration damping, and encapsulating parts or assemblies.

For use in electronics, the silicone must NOT create any acid while curing. If it smells like vinegar at any time, don't use it! It will eventually cause corrosion. A silicone adhesive safe for electronics WILL cost more than what the home center carries, because it is a specialty product.

An example of a suitable product is this, from Amazon (USA): GC ELECTRONICS 19-155 ADHESIVE, SILICONE, TUBE, 3FL.OZ.(US) (1 piece) https://www.amazon.com/dp/B004SPJN6K/ref=cm_sw_r_cp_apa_i_ZnexCb4WZPT1X




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LukeW:
Generally, when choosing a material like this, these are the factors we're interested in:

- Neutral-cure silicone. A lot of hardware-store 1-pack silicones are acetoxysilane based which will release acetic acid in the curing reaction, which will corrode nearby things - you don't want this, you really want a neutral-cure silicone. This is probably the most important thing, and if you can buy a neutral-cure Home Depot silicone for a couple of bucks it's probably fine.

- One-pack, because it's more convenient than mixing a binary system.

- RTV (room-temperature vulcanising), i.e. it chemically sets and crosslinks by itself at room temperature, going hard with the desired shore and mechanical properties.

- Has some "bounce", which is the main motivation for choosing a silicone over a polyurethane.

- Cheap and locally available for you in a non-bulk pack.

- High dielectric strength, although if you're not using it for HV applications anything is probably fine.

Personally, I like Dow Corning 738, which is available in a small tube.

It's actually documented as an engineering material - it has a datasheet, and if we want to know, say, the dielectric strength, it's documented.

https://www.ellsworth.com/products/by-manufacturer/dow/sealants/silicone/dow-738-electrical-sealant-silicone-white-90-ml-tube/

xavier60:

--- Quote from: ender4171 on February 04, 2019, 05:26:49 pm ---Dave and others often talk about components being tied down with silastic.  I have found the OG Dow/Corning 732 stuff, but it is pricey and not available in small quantities (way more than I would use in time without it going bad).  Is there anything really special about it other than it is a neutral cure silicone?  I was thinking of grabbing some GE Silicone II, which is also neutral cure and is available at any home store in small tubes.  Does anyone have experience with that product, or have any recommendations for an alternative that is readily available?

--- End quote ---
I have been using ThreeBond(Japan) 1530C for years. It is moisture curing and non corrosive. Because it self levels, it gives a neat result.
The product isn't easily available in Australia. It is now available on ebay in retail blister pack. Be certain to read the review.
https://www.ebay.com/p/2-Pcs-Tube-Tb1530c-All-Purpose-Adhesive-Glue-Clear-Extra-Strong-Wood-Elasticity/18024574076?iid=173609103986

djacobow:
What do you guys think of zip ties for caps? Just put a few extra holes in the PCB design and feed the tie around the back. Seems like it would work nicely for elcos on their sides. Maybe with some silpat or other foam to provide tension.

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