The data required to process a chip card transaction is stored on the card in a microchip, whereas traditional cards store that info in the magnetic stripe on the back side of the card. (smallbusinessesdoitbetter.com)
Use some velcro on the back side of each card. (tes.com)
Cut out the boards and the cards and use velcro dots in the middle of each blank square on the boards and on the back side of each card. (tes.com)