Ball grid array package substrate with through holes and method of forming same

A substrate of a ball grid array package, the substrate comprising:

• a first layer including reinforcement fibers, wherein the first layer has a first surface and a second surface substantially parallel to the first surface and the reinforcement fibers reinforce the first layer such that the first layer has a higher tensile strength relative to a layer in the ball grid array package that is free of reinforcement fibers;
• a second layer disposed adjacent to the first surface of the first layer, wherein:
• the second layer is free of reinforcement fibers,
• the second layer includes (i) a first surface disposed adjacent to the first surface of the first layer and (ii) a second surface substantially parallel to the first surface,
• the second surface of the second layer includes a circuit pattern having a number of lines, and
• at least a portion of the number of lines have a width less than 20 microns;
• a third layer disposed adjacent to the second surface of the first layer, wherein the third layer is free of reinforcement fibers;
• and
• a through hole penetrating each of the first layer, the second layer, and the third layer.