Method of manufacturing the printed board

Patent metadata

Field	Value
Publication number	US-11229123-B2
Application number	US-201715719565-A
Country	US
Kind code	B2
Filing date	Sep 29, 2017
Priority date	Sep 30, 2016
Publication date	Jan 18, 2022
Grant date	Jan 18, 2022

Abstract

A method of manufacturing a printed board, the method comprising: a first step of preparing a laminate having a base member in which a plurality of layers of glass cloths and a plurality of resin layers are alternately laminated, a first metal layer attached to one surface of the base member, and a second metal layer attached an opposite surface of the base member; a second step of forming a protective layer removable with a predetermined solvent on each of the first metal layer and the second metal layer; and a third step of irradiating the laminate on which the protective layer is formed with a laser beam to thereby form a through-hole penetrating in a thickness direction of the laminate.

First claim

What is claimed is:

1. A method of manufacturing a printed board, the method comprising:
preparing a laminate having a base member in which a plurality of layers of glass cloths and a plurality of resin layers are alternately laminated, a first metal layer attached to one surface of the base member, and a second metal layer attached to an opposite surface of the base member;
forming a protective layer on each of the first metal layer and the second metal layer after preparing the laminate;
forming a through-hole penetrating in a thickness direction of the laminate by irradiating the laminate on which the protective layer is formed with a laser beam after forming the protective layer;
removing the protective layer with a solvent after forming the through-hole; and
forming a third metal layer by plating after removing the protective layer,
wherein the protective layer is formed of a dry film made of a resin selected from acrylic resin, epoxy-based resin, and urethane-based resin,
wherein the protective layer has a thickness of at least 15 micrometer (μm) and at most 75 micrometer (μm),
wherein the base member has at least three layers of glass cloths,
wherein the base member has a thickness of at least 200 micrometer (μm) and at most 500 micrometer (μm),
wherein, in forming the through-hole, the protective layer on the first metal layer thermally contracts such that decomposed matter is formed on an exposed portion of the first metal layer,
wherein the third metal layer continuously covers the first metal layer, the decomposed matter on the first metal layer, the second metal layer, and an inner side surface of the through-hole, and
wherein, in forming the through-hole, a width of the through-hole is at least 10 micrometer (μm) and at most 30 micrometer (μm).

2. The method of manufacturing a printed board according to claim 1 ,
wherein, in forming the through-hole, the laminate on which the protective layer is formed is irradiated with the laser beam so as to circularly scan along an outer edge of an opening as the through-hole.

3. The method of manufacturing a printed board according to claim 1 ,
wherein, in forming the through-hole, as an opening, a plurality of elongated holes parallel to each other in a plan view are formed.

4. The method of manufacturing a printed board according to claim 3 ,
wherein, in forming the through-hole, the laser beam is applied from the first metal layer side such that in the plan view, a minor radius of the elongated hole on a side of the first metal layer is greater than a minor radius of the elongated hole on a side of the second metal layer, and that the difference between the minor radiuses is at most 20 micrometer (μm).

5. The method of manufacturing a printed board according to claim 1 ,
wherein, in removing the protective layer, the protective layer is removed with an alkaline solution as the solvent.

6. The method of manufacturing a printed board according to claim 1 , further comprising:
forming wiring patterns by etching the first metal layer, the second metal layer, and the third metal layer after forming the third metal layer, and
wherein a material of the protective layer is the same as the material to be used as an etching mask in forming wiring patterns.

7. The method of manufacturing a printed board according to claim 1 ,
wherein, in forming the through-hole, an oscillation wavelength of the laser beam is at least 250 nanometer (nm) and at most 2000 nanometer (nm).

8. The method of manufacturing a printed board according to claim 1 ,
wherein, in forming the through-hole,
a laser power is at least 10 W and at most 60 W;
a repetition frequency of the laser beam is at least 100 kHz and at most 3000 kHz, and
a scan speed of the laser beam is at least 1000 mm/sec and at most 3000 mm/sec.

9. The method of manufacturing a printed board according to claim 1 ,
wherein, in forming the through-hole,
a focal point of the laser beam is positioned to an inside of the base member of the laminate;
a wavelength of the laser beam is 355 nanometer (nm);
a pulse energy of the laser beam is at least 3 microjoule (μJ);
a fluence of the laser beam on a surface of the laminate is at least 3 J/cm 2 ;
a fluence of the laser beam at the focal point is at least 10 J/cm 2 ;
an interval between irradiation cycles of the laser beam at the same point on the laminate in a plan view is at least 5 milliseconds (ms).

10. The method of manufacturing a printed board according to claim 1 ,
wherein, a pulse width of the laser beam is at least 10 picoseconds (ps) and at most 100 nanoseconds (ns).

11. The method of manufacturing a printed board according to claim 1 ,
wherein, in forming the through-hole, a width of the laser beam is at least 10 micrometer (μm) and at most 30 micrometer (μm).

12. The method of manufacturing a printed board according to claim 1 ,
wherein the first metal layer has a thickness of at least 1 micrometer (μm) and most 18 micrometer (μm), and wherein the first metal layer is made of one or more than one metal selected from Cu, Ag, Au, Ni, and Al or an alloy containing any of these metals as its main component.

13. The method of manufacturing a printed board according to claim 1 ,
wherein the second metal layer has a thickness of at least 1 micrometer (μm) and most 18 micrometer (μm), and wherein the second metal layer is made of one or more than one metal selected from Cu, Ag, Au, Ni, and Al or an alloy containing any of these metals as its main component.

14. The method of manufacturing a printed board according to claim 1 ,
wherein, in forming the through-hole, the protective layer formed on the laminate thermally contracts by the laser beam, and
wherein a thermal contraction width on a side of the first metal layer is greater than a thermal contraction width on a side of the second metal layer.

15. The method of manufacturing a printed board according to claim 1 ,
wherein, in forming the through-hole, the protective layer on the second metal layer thermally contracts such that decomposed matter is formed on an exposed portion of the second metal layer, and
wherein, in forming the through-hole, a thermal contraction width of the protective layer on the second metal layer is less than or equal to half of a thermal contraction width of the protective layer on the first metal layer.

16. The method of manufacturing a printed board according to claim 15 ,
wherein the third metal layer continuously covers the first metal layer, the decomposed matter on the first metal layer, the second metal layer, the decomposed matter on the second metal layer, and the inner side surface of the through-hole.

17. The method of manufacturing a printed board according to claim 16 ,
wherein, in forming the through-hole, a size of the decomposed matter formed on the exposed portion of the first metal layer is about 10 micrometer (μm).

18. The method of manufacturing a printed board according to claim 1 ,
wherein, in forming the through-hole, a size of the decomposed matter formed on the exposed portion of the first metal layer is about 10 micrometer (μm).

19. The method of manufacturing a printed board according to claim 1 ,
wherein, in forming the through-hole, the laminate on which the protective layer is formed is irradiated with the laser beam so as to circularly scan laser-beam irradiation areas multiple times.

Assignees

• Nichia Corp

Inventors

• Katsumata Masaaki
• Sakamoto Masakazu

Classifications

• H05K3/427

  initial plating of through-holes in metal-clad substrates · CPC title

• H05K1/0366

  reinforced, e.g. by fibres, fabrics (H05K1/036 takes precedence) · CPC title

• H05K3/403

  Edge contacts; Windows or holes in the substrate having plural connections on the walls thereof (H05K3/4092 takes precedence) · CPC title

• H05K2203/1383

  Temporary protective insulating layer · CPC title

• H05K3/384

  by plating · CPC title