Double layer circuit board

Provided is a double layer circuit board and a manufacturing method thereof. The double layer circuit board comprises a substrate, a first circuit layer formed on a first surface of the substrate, a second circuit layer formed on a second surface of the substrate, and at least one connecting pillar formed in and covered by the substrate. Each one of the at least one connecting pillar includes a first end connected to the first circuit layer and a second end connected to the second circuit layer. A terminal area of the second end is greater than a terminal area of the first end. Therefore, the second circuit layer is firmly connected to the first circuit layer through the at least one connecting pillar. A yield rate of the double layer circuit board may be increased.