Method for manufacturing multi-layer printed circuit board

A method for manufacturing a build-up type multi-layer printed circuit board, with an insulating layer being stacked upon a CCL (copper clad laminate) with a circuit pattern already formed thereon, and a circuit pattern being formed again on said insulating layer, these being repeated,

• the method comprising the steps of:
• stacking a resin-clad copper foil (RCC) on said CCL after forming a first printed circuit layer having a first circuit pattern, and heating and pressing this structure;
• forming a via hole in said RCC thus heated and pressed, for forming inter-layer connections;
• carrying out a plating on said board with a via hole formed therein, to form an electrically conducting layer for inter-layer electrical connections;
• forming a second printed circuit layer having a second circuit pattern on said board thus plated;
• stacking another RCC on said board after forming said second printed circuit layer, heating and pressing said RCC, forming a plated layer on it, and forming a third printed circuit layer having a third circuit pattern;
• and
• forming a protecting layer on said board after forming said third printed circuit layer,
• wherein said via hole for connecting said first circuit pattern of said first printed circuit layer to said second circuit pattern of said second printed circuit layer is formed by irradiating beams of an Nd-YAG laser to a relevant position to remove all copper foil of said RCC, and then, by irradiating beams of a CO.sub.2 laser to a copper-foil-removed position to remove all of residual resin of RCC;
• and
• wherein said via hole for connecting said first circuit pattern of said first printed circuit layer to said third circuit pattern of said third printed circuit layer is formed by irradiating beams of an Nd-YAG laser to a relevant position to remove copper foil at least down to said second circuit pattern, and then, by irradiating beams of a CO.sub.2 laser to a copper-foil-removed position to remove all of residual resin of said first circuit pattern.

A method for manufacturing a build-up type multi-layer printed circuit board, with an insulating layer being stacked upon a CCL (copper clad laminate) with a circuit pattern already formed thereon, and a circuit pattern being formed again on said insulating layer, these being repeated,

• the method comprising the steps of:
• stacking a resin-clad copper foil (RCC) on said CCL after forming a first printed circuit layer having a first circuit pattern, and heating and pressing this structure;
• forming a via hole in said RCC thus heated and pressed, for forming inter-layer connections;
• carrying out a plating on said board with a via hole formed therein, to form an electrically conducting layer for inter-layer electrical connections;
• forming a second printed circuit layer having a second circuit pattern on said board thus plated;
• stacking an RCC on said board again after forming said second printed circuit layer, heating and pressing said RCC, forming a plated layer on it, and forming a third printed circuit layer having a third circuit pattern;
• repeating above procedures for forming respective printed circuit layers up to an nth printed circuit layer having an nth circuit pattern;
• and
• forming a protecting layer on said board after forming said nth printed circuit layer,
• wherein said via hole for connecting two or more circuit patterns is formed by irradiating beams of an Nd-YAG laser to a relevant position to remove from an uppermost printed circuit layer to a printed circuit layer disposed immediately above a lowermost printed circuit layer, and then, by irradiating beams of a CO.sub.2 laser to a layer-removed position to remove all of residual resin of RCC of a lowermost printed circuit layer.