We have the proper crimper & other tools to work with the top component that locks into the showed on the above link bottom JST so that technicality is taken care of. We are just asking if anyone has similar first hand pin dipping or thin coating experience with the various brands of conductive silver epoxy. All pertinent terminal components will be brand new & clean so the conductive epoxy should adher properly it seems.
I know this is possibly a more expensive approach than some of you that are extra good at soldering would do. It seems that this could be a viable alternative in a limited way ... but with good long term results. Even though the bottom JST socket fits fairly snug ... I am thinking that a tiny amount of the conductive silver epoxy would cement the JST base permanently in. I would think it would get rid of possible misreading of a pin or missed output from the base of the pin itself. I am thinking this could be better than "press fit terminals" for reliability & long term results.
Hopefully, someone with hands on experience with the conductive silver epoxy can set me & possibly others straight on the viability of what I described.
I'd only use conductive epoxy as a last resort. I used it once because I couldn't get solder to "stick" when I tried to re-solder the connectors to the defroster in the glass hatch-window my car.
I've worked in electronics for many years and I've never seen it used in production. As far as I know, it's only for "repairs" when the normal methods don't work.
Normally connectors should "just work". When connectors fail, it's usually mechanical damage such as a broken wire from flexing/pulling the wires, or it can be corrosion.
If there is stress on the connector, or excessive vibration, etc., a latching connector and/or a strain relief may be a better solution. Or, just direct-solder the wires without any connector. (Sometimes with solder, you need a separate strain relief so the solder joints are not stressed when there is tension on the wires.)
The fitting issue that we are seeing is some inconsistencies of how tight the proper size external male pins fit from board to board. I figured that unless the strength, viscosity or conductivity of the silver epoxy would be problem ... it could be just one of many options to eliminate looseness. Albeit for most professionals it would not their first choice. It would make the JST bottom connectors permanently cemented in the Mega or Uno but we are OK with that with this specific usage.
There are pieces of equipment that we have where the manufacturer's board (its terminals) allows us to directly plug in the upper part of the JST which has worked out for several years without any issues in a tough environment. As long as we use the recommended JST crimping tool & wire size for that specific JST component. Here is a link to the upper part:
I already bought over 30 Redboards from SparkFun & they are SMT boards with their own receiving headers. So that is a factor too. Once the top JST XH are on there should be no pulling off or on so it looks like I just have to make sure that I put the minimum amount of epoxy ... I wonder if the conductive epoxy is thin enough so it does not migrate within the original SMT soldering on the UNO clone Redboard.
So that is another compelling reason in my view to use conductive epoxy to firm up each connection & make it less likely to have any gaps in conductivity. I know it is not the norm ... soldering in open holes is ... but with sealed smt style board it seems that the surface soldering would be more difficult. Also it seems it would be a struggle to take off the existing headers normally used with the little wires with male ends that come with the hobby kits.
The connectors that you linked to are 2.5mm pitch. As far as I know the connectors used on Arduinos are all 0.1" (=2.54mm) pitch.
The difference doesn't sound much, but for long connectors such as the ones found on the Mega there will be a problem with compatibility.
Contacts are always a weak point in an electronic assembly.
Conductive epoxy has 100 x more resistance than copper. Which over a small distance might be OK. However you will have to make sure at least most of the volume between the pin and board hole ID has epoxy. You must also make sure the board cladding is ROHS compliant (i.e. be sure there is no lead in the solder reflow on the board). Not much sticks to lead.
So my thoughts are:
I can solder pretty well (just so you know)
I think soldering would be much more reliable. Especially if the target environment has temperature variations
You will likely have to learn how to solder eventually you might take the opportunity to learn. You can purchase various over run/scrap boards for soldering practice.
Usually soldering is not very difficult. Un-soldering can be a challenge.
In my years in automotive (OEM) I've had to deal with a disproportional amount of connection issues.
i.e. connections are often a trouble spot.
Do you know the "snug" fit applies to all the boards you plan on building?
As for epoxy migrating, it will depend on your technique, how thick/thin your epoxy and how you position them to cure. You should probably practice the epoxy technique with some scrap parts.
Unfortunately if the epoxy isn't reliable, you will likely not know until somewhere down the road (in time) and at that point soldering will no longer be an option (on the epoxied boards)
I am thinking this could be better than "press fit terminals" for reliability & long term results.
The electrical and electronics industries have managed to build press fit terminals that handle thousands of amps with no reliability issues in what amounts to billions of operational years.
You've already convinced yourself that "conductive silver epoxy" is some kind of improvement over the industry status quo. It's not. Maybe it has a place in specialty repairs but it would never find a home in a manufacturing process where the correct connector and solder would prevent the problem from ever occurring. The best solution to a problem is the one that never needs to be implemented.
Mis-applying a male pc board connector with the wrong pitch and undocumented pin length is creating a problem that doesn't need a miracle cure, it just needs the correct connector.
The electrical and electronics industries have managed to build press fit terminals that handle thousands of amps with no reliability issues in what amounts to billions of operational years.
Although I would argue that "no reliability issues" is overstated I agree that designed press fit terminals can be a reliable solution.
Perhaps I misunderstood the OP's description. I was under the impression that what was being described as a "press fit" was simply the fact that there was some (minor?) interference when putting the JST part into the plated through hole.
