Board surface leveling method of loop-free blind hole high-density interconnection printing circuit board

Abstract

The invention relates to a board surface leveling method of a loop-free blind hole high-density interconnection printing circuit board, which has the technical key point that the outer layer of a high-density interconnection printing circuit board is performed with whole board plating and is put into a scrubbing machine with the transmission speed of 1.5-2.0m / min; the pressure of a brush roll cooling water nozzle is 1.0-1.5 kg / cm<2>, the temperature of cooling water is 20-30 DEG C, brush roll grinding current is 0.8-1.2A, the horizontal swinging amplitude of the brush roll is 5mm, and the swinging frequency is 350 times / min; and the board surface of the high-density interconnection printing circuit board is ground and levelled. As the board surface of the printing circuit board is ground to be levelled, blind hole surface and surface copper are on the same horizontal plane; when a dry film is pasted, the blind hole can be tightly stuck with the dry film without adding a welding ring; during acid etching, blind hole integrity is not damaged, thus effectively improving the wiring density of the board surface of the printing circuit board.

Description

technical field [0001] The invention relates to a method for leveling the surface of a high-density interconnection printed circuit board without ring blind holes. Background technique [0002] When the high-density interconnection HDI printed circuit board is finished with laser drilling blind holes and whole board electroplating, there will be a certain drop between the surface of the blind holes and the copper foil on the surface, that is, there will be pits at the blind holes, so that the surface of the copper layer will appear Pit phenomenon, so when the dry film is pasted, there is a gap between the dry film and the blind hole due to the pits on the surface of the blind hole, so the line at each blind hole must have a hole that is 0.2mm larger than the blind hole Welding ring, so that the blind hole is isolated from the etching solution and will not be etched away, so that the etching solution will not enter the gap during acid etching, causing the copper foil at the b...

AI Technical Summary

Problems solved by technology

[0002] When the high-density interconnection HDI printed circuit board completes the laser drilling blind hole and the whole board electroplating, there will be a certain gap between the surface of the blind hole and the copper foil on the surface, that is, there will be pits at the blind hole, so that the surface of the copper layer will appear Pit phenomenon, so when the dry film is pasted, there is a gap between the dry film and the blind hole due to the pits on the surface of the blind hole, so the line at each blind hole must have a hole that is 0.2mm larger than the blind hole Welding ring, so that the blind hole is isolated from the etching solution and will not be etched away, so that the etching solution will not enter the gap during acid etching, causing the copper foil at the blind hole to be etched away, resulting in the problem of non-porous open circuit

Since each blind hole needs a welding ring 0.2mm larger than the blind hole, the welding ring occupies a large wiring space, thus greatly limiting the wiring density of the printed circuit board