As I mentioned in the support ticket, dual interface cards (cards that have a contact interface and a contactless interface in the same card) are not generally convertible.
Standard dual interface cards have a contact module (the gold plates you see on the card) for inserting the card into a machine, and an antenna hidden inside the card for contactless. The two methods of manufacturing are;
1. traditional dual interface
They put the silicon chip on the back of the contact interface, wirebond the pads on the chip to the appropriate contact pads on the contact side of the module, and then wirebond the contactless antenna pads on the silicon chip to the contactless antenna traces, then finally seal the silicon chip up with epoxy resin before squishing it into the PVC plastic of the full size card. The difficulty working with this type of card is that generally speaking the antenna coil wire inside the card is fragile, but worse, the hair-thin wirebonds coming from the silicon chip, through the epoxy resin, to the antenna coil in the card are extremely fragile and will readily break almost immediately when you try to work with the module. This also makes extracting the silicon chip from epoxy on the back of the module itself nearly impossible as the wirebonds are guaranteed to break, but also the silicon chip itself could just snap.
This is why we donāt bother with dual interface cards at all.
2. coil on module
CoM is interesting because they create a PVC card first with a two-inductor antenna inside, one full size and one very small which is designed to sit directly under the CoM (coil on module)ā¦ so basically the difference is that the CoM module is made similarly to traditional dual interface cards except the contactless antenna the silicon chip is wirebonded to is very small and completely self-contained on the back side of the contact module. This means they can just plot the CoM down into a āsocketā in the PVC card with a little bit of basic adhesive and it will workā¦ the two small antennas will line up and act like a bridge to the larger antenna in the card.
We are able to work with this type of device because removing the CoM from the PVC card is relatively easy, however as @Satur9 stated, for it to really have a chance of working with the payment terminal, it will need to be placed over a much smaller version of what the PVC card is attempting to do. His CoM conversion antenna is actually two antennasā¦ one small one to sit under the CoM module and a slightly larger one to make the module perform with the bare minimum required to actually talk to the payment terminal.
your best bet
Because you want to put this into a wand, you have a couple options in my opinion;
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try to use a CoM card but taking a risk and winding your own antenna coil. Basically you would extract the CoM from the card, then carefully scrape the small antenna off the back of it, then solder some magnet winding wire to the two appropriate contact pads on the front of the module. The CoM will have two pads on the front which you can see other people have posted (and circled in red) which the traditional dual interface modules generally donāt have, which is why you could remove the antenna from the back side of the CoM and just solder your own antenna wire to the contact pads on a CoM. Anyway, then you would put the module in the handle where there is space, run some magnet winding wire up the inside of the wand, and wind your own cylindrical coil around a pencil or something, and place it into the tip of the wand. This is not easy and requires patience, soldering skill, math, and some good luckā¦ but it is technically possible.
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your other option is to basically do the same thing but try to carefully extract a dual interface module from a card but cut short the existing antenna coil with enough left hanging out of the module that you can solder / connect magnet winding wire to itā¦ and then try the sameā¦ place the module in the handle and hand wind your own cylindrical coil etc.
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offer to pay someone (not us) to do this for you. Frankly I donāt have the skill or patience to do it, and even if I did the cost would be insaneā¦ but then again the cost to pay anyone with the skill to do this would probably also be insaneā¦ it just depends on what your budget is for this project I guess.
