Method of manufacturing fpcb substrate

A method for manufacturing a flexible printed circuit board substrate, the method comprising:

• providing a flexible printed circuit board material comprising an insulation layer and an electrically conductive layer formed on the insulation layer, the electrically conductive layer having a first surface and a second surface at an opposite side thereof to the first surface, the insulation layer having a third surface and a fourth surface at an opposite side thereof to the third surface, the third surface of insulation layer coming into contact with the second surface of the electrically conductive layer;
• forming a first through hole extending from the first surface of the electrically conductive layer to the fourth surface of the insulation layer, the first through hole comprising a metal hole in the electrically conductive layer and an insulation hole in the insulation layer;
• enlarging the insulation hole to expose a portion of the electrically conductive layer around the metal hole;
• and
• bending the exposed portion of the electrically conductive layer to form a hook which passes through the enlarged insulation hole and protrudes out from the fourth surface of the insulation layer.