A method for forming a
printed circuit board (100), comprising (a) Providing a substrate made of a first malleable
polymer material, wherein the substrate has at least one
electrical conductor on a surface; (b) Laminating a cover layer of a second malleable
polymer material onto the substrate to form a flexible
printed circuit board (104), wherein the at least one
electrical conductor is arranged between the cover layer and the substrate, the cover layer having a plurality of holes which
expose at least part of the at least one
electrical conductor; (c) electrically connecting light-emitting diodes (LEDs) (108) to exposed sections of the at least one electrical conductor; and (d) Heating the flexible
printed circuit board (104) by applying a force to cause the flexible printed circuit board (104) to bend and assume a shape with an arcuate cross-section; and (e) Cooling the flexible printed circuit board (104) until the shape is fixed, thereby forming a thermoformed printed circuit board (100) with an arc-shaped cross-section, wherein step (d) comprises: Arranging the flexible printed circuit board (104) in a mold (200), wherein the mold (200) has an upper half (204) and a
lower half (202), wherein the upper half (204) has an elongated, convex longitudinal projection (212) having a channel (218) corresponding to a position of the LEDs (108), wherein the channel (218) has a size that prevents the LEDs (108) from touching the upper half (204) when the mold (200) is closed, wherein the
lower half (202) has an elongated, concave longitudinal recess (210) for receiving the longitudinal projection (212) of the upper half (204), wherein the longitudinal projection (212) and the longitudinal recess (210) have a similar arcuate cross-section; Closing the mold (200) while the mold (200) and the flexible printed circuit board (104) are heated at a
thermoforming temperature; and Holding the mold (200) in a closed position to give the printed circuit board (100) a shape with an arc-shaped cross-section, wherein the mold (200) has slots (220) in the
lower half (202) for receiving longitudinal edges of the printed circuit board (100) and arranging the flexible printed circuit board (104) in the mold (200) includes inserting the printed circuit board edges into the slots (220).