US Pat. No. 10,973,129


Lumet Technologies Ltd., ...

1. A method of applying a pattern of electrical conductors to a substrate formed by a surface of a solar cell, which method comprises:a) providing a continuous flexible membrane comprising a formable thermoplastic polymer capable of being cast and/or embossed and being conformable to the surface of the substrate, wherein a first surface of the membrane has a pattern of grooves cast therein, and/or embossed therein by advancing the membrane between a die roller and a counter die, the die roller having protruding rules complementary to the pattern of grooves to be formed on the membrane, the pattern corresponding at least partially to a desired pattern of electrical conductors to be applied to the substrate;
b) loading into the grooves of the first surface of the membrane a composition that includes, as composition components, electrically conductive particles and an adhesive, said loading being performed in one or more filling cycle(s) such that on completion of loading the composition substantially fills the grooves, level with the first surface of the membrane, and parts of the first surface between the grooves are substantially devoid of the composition;
c) bringing the first surface of the membrane into contact with the substrate;
d) applying pressure to the membrane to cause the composition loaded into the grooves in the first surface of the membrane to adhere to the substrate;
e) separating the membrane from the substrate to transfer the composition from the grooves in the first surface of the membrane to the substrate; and
f) applying sufficient energy to sinter the electrically conductive particles and to render electrically conductive the pattern of composition transferred to the substrate from the grooves;
wherein at least a portion of the electrical conductors applied thereby have a tapering cross section profile having a base width WB and a height h, such that a dimensionless aspect ratio ASP between the height and the base width (ASP=h/WB) of the profile is within a range of 5:1 to 1:5.