The invention discloses a forming process for a
fine line circuit with
line width being below 0.05mm of a flexible
printed circuit board, aiming to manufacture an IC (
Integrated Circuit)
package flexible substrate which has a
copper-coated base material with the width being below 40 mu m and is 0.05mm in
line width. The forming process for the
fine line circuit with the
line width being below 0.05mm of the flexible
printed circuit board comprises the following steps of: material selecting,
laser-based
blind hole drilling, hole blacking, wet-process dry film attaching,
exposure for development,
blind hole electroplating, film removing and cleaning, secondary wet-process dry film attaching, secondary
exposure for development, and circuit
etching. Compared with the prior art, the IC
package flexible substrate, which has the
copper-coated base material with the width being below 40 mu m, is 0.05mm in line width and is manufactured through the steps of material selecting,
laser-based
blind hole drilling, hole blacking, wet-process dry film attaching,
exposure for development, blind hole
electroplating, film removing and cleaning, secondary wet-process dry film attaching, secondary exposure for development and circuit
etching, fully meet a wiring requirement of the IC
package flexible substrate, and is simple in process, low in cost, high in qualification rate and suitable for industrialized production.