Manufacturing method of deep V blind hole of HDI board

The invention discloses a method for manufacturing a deep V blind hole of an HDI board. The method comprises the flow of cutting, inner-layer line (including PAD) manufacturing, pressing, browning thin copper manufacturing, laser drilling, mechanical drilling, hole filling electroplating and resin hole plugging. The method comprises the following steps that: (1) during the inner-layer line manufacturing, a blind hole bearing PAD is arranged on an L3 layer, and a blind hole limiting PAD is arranged on an L2 layer; (2) an inner target of a laser alignment target is designed before laser drilling, specifically, an L1-2-3 mode is adopted for design, an L1 layer and the L3 layer are all copper sheets, and a 0.8 mm round hole is etched in the L2 layer; and (3) laser drilling operation is performed, specifically, the laser drilling is adopted, windowing ablation is conducted on the L1 layer to form a 3.5 * 3.5 mm stepped hole till a 0.8 mm round hole penetrating through the L2 layer is ablated to the bearing PAD of