Silver Conductive Epoxy
Silver conductive epoxy is essentially a highly conductive glue which opens up possibilities for attaching components to a PCB without using any soldering or special tools. This makes it very useful for producing circuits on temperature sensitive substrates and quickly prototyping circuits in a safe fashion (ie. for kids or beginners).
The epoxy often comes packaged in a syringe but the tip can be swapped for a blunt plastic needle for safer use by children. The epoxy must be used sparingly as it is not particularly cheap but can be applied to almost any surface or material. The setting time for a complete hold is around 2 hours but this can be shortened to minutes with some hot air (approx 100C or 200F) from a re-flow gun or hair-dryer. Great care must be taken when applying to fine pitch components or tracks to prevent accidental shorts.
- Relatively easy to use - requires no training or skill like soldering but it can be easy to short component pins or tracks if you're not careful.
- Safe to use - non-toxic and does not require high temperatures
- Doesn't destroy tracks - unlike soldering where it is possible to pull up tracks, placing down conductive epoxy will not harm tracks.
- Low Temperature - Because high temperatures aren't needed, you can attach components on a substrate that would melt or burn severely during soldering.
- Expensive to source - Silver conductive epoxy contains silver itself because the conductivity would otherwise not be sufficient, this makes it more expensive than solder.
- Shelf life - Because it is an epoxy that chemically sets, silver conductive epoxy does have a shelf life after which it won't bond very well and becomes clumpy. This life varies on the composition of the epoxy as well as the conditions of storage.
- Intermittent connection - Because the connection is very brittle after setting, it's very easy for micro cracks to form in the epoxy, this means that flexing the connection can cause intermittency.
- Difficult to fix errors - Because the epoxy can bind quite well to some surfaces, if you accidentally short some tracks or pins it becomes very difficult to fix. Solder can be de-soldered and a component can be pulled back off z-axis tape but conductive epoxy can't be removed easily.
List of all substrates compatible with the z-axis tape application method:
|Linen Paper||Stone Paper|
|3D Printed Substrate||Microfibre Cloth|