a method of welding materials includes obtaining a first material having a first thermoplastic layer formed thereon ; obtaining a second thermoplastic layer ; positioning the first material and the second thermoplastic layer such that the first thermoplastic layer faces the second thermoplastic layer ; applying energy to the first thermoplastic layer and the second thermoplastic layer at a first location to establish a first weld ; applying energy to the first thermoplastic layer and the second thermoplastic layer at a second location , the second location being offset from the first location , a portion of the second location overlapping a portion of the first location .