Abstract: An opening is formed in resin 20 by a laser beam so that a via hole is formed. At this time, copper foil 22, the thickness of which is reduced (to 3 ?m) by performing etching to lower the thermal conductivity is used as a conformal mask. Therefore, an opening 20a can be formed in the resin 20 if the number of irradiation of pulse-shape laser beam is reduced. Therefore, occurrence of undercut of the resin 20 which forms an interlayer insulating resin layer can be prevented. Thus, the reliability of the connection of the via holes can be prevented. Thus, the reliability of the connection of the via holes can be improved.

Abstract: An opening is formed in resin 20 by a laser beam so that a via hole is formed. At this time, copper foil 22, the thickness of which is reduced (to 3 ?m) by performing etching to lower the thermal conductivity is used as a conformal mask. Therefore, an opening 20a can be formed in the resin 20 if the number of irradiation of pulse-shape laser beam is reduced. Therefore, occurrence of undercut of the resin 20 which forms an interlayer insulating resin layer can be prevented. Thus, the reliability of the connection of the via holes can be improved.

Abstract: Mesh holes 35a and 59a of upper solid layers 35 and upper solid layers 59 are formed to overlie on one another, so that the insulating properties of interlayer resin insulating layers 50 are not lowered. Here, the diameter of each mesh hole is preferably 75 to 300 ?m. The reason is as follows. If the diameter of the mesh hole is less than 75 ?m, it is difficult to overlay the upper and lower mesh holes on one another. If the diameter exceeds 300 ?m, the insulating properties of the interlayer resin insulating layers deteriorate. In addition, the distance between the mesh holes is preferably 100 to 2000 ?m. The reason is as follows. If the distance is less than 100 ?m, the solid layer cannot function. If the distance exceeds 2000 ?m, the deterioration of the insulating properties of the interlayer resin insulating film occurs.

Abstract: An opening is formed in resin 20 by a laser beam so that a via hole is formed. At this time, copper foil 22, the thickness of which is reduced (to 3 ?m) by performing etching to lower the thermal conductivity is used as a conformal mask. Therefore, an opening 20a can be formed in the resin 20 if the number of irradiation of pulse-shape laser beam is reduced. Therefore, occurrence of undercut of the resin 20 which forms an interlayer insulating resin layer can be prevented. Thus, the reliability of the connection of the via holes can be improved.

Abstract: Mesh holes 35a and 59a of upper solid layers 35 and upper solid layers 59 are formed to overlie on one another, so that the insulating properties of interlayer resin insulating layers 50 are not lowered. Here, the diameter of each mesh hole is preferably 75 to 300 ?m. The reason is as follows. If the diameter of the mesh hole is less than 75 ?m, it is difficult to overlay the upper and lower mesh holes on one another. If the diameter exceeds 300 ?m, the insulating properties of the interlayer resin insulating layers deteriorate. In addition, the distance between the mesh holes is preferably 100 to 2000 ?m. The reason is as follows. If the distance is less than 100 ?m, the solid layer cannot function. If the distance exceeds 2000 ?m, the deterioration of the insulating properties of the interlayer resin insulating film occurs.

Abstract: Mesh holes 35a and 59a of upper solid layers 35 and upper solid layers 59 are formed to overlie on one another, so that the insulating properties of interlayer resin insulating layers 50 are not lowered. Here, the diameter of each mesh hole is preferably 75 to 300 ?m. The reason is as follows. If the diameter of the mesh hole is less than 75 ?m, it is difficult to overlay the upper and lower mesh holes on one another. If the diameter exceeds 300 ?m, the insulating properties of the interlayer resin insulating layers deteriorate. In addition, the distance between the mesh holes is preferably 100 to 2000 ?m. The reason is as follows. If the distance is less than 100 ?m, the solid layer cannot function. If the distance exceeds 2000 ?m, the deterioration of the insulating properties of the interlayer resin insulating film occurs.

Abstract: An opening is formed in resin 20 by a laser beam so that a via hole is formed. At this time, copper foil 22, the thickness of which is reduced (to 3 ?m) by performing etching to lower the thermal conductivity is used as a conformal mask. Therefore, an opening 20a can be formed in the resin 20 if the number of irradiation of pulse-shape laser beam is reduced. Therefore, occurrence of undercut of the resin 20 which forms an interlayer insulating resin layer can be prevented. Thus, the reliability of the connection of the via holes can be improved.

Abstract: An opening is formed in resin 20 by a laser beam so that a via hole is formed. At this time, copper foil 22, the thickness of which is reduced (to 3 ?m) by performing etching to lower the thermal conductivity is used as a conformal mask. Therefore, an opening 20a can be formed in the resin 20 if the number of irradiation of pulse-shape laser beam is reduced. Therefore, occurrence of undercut of the resin 20 which forms an interlayer insulating resin layer can be prevented. Thus, the reliability of the connection of the via holes can be improved.

Abstract: An opening is formed in resin 20 by a laser beam so that a via hole is formed. At this time, copper foil 22, the thickness of which is reduced (to 3 ?m) by performing etching to lower the thermal conductivity is used as a conformal mask. Therefore, an opening 20a can be formed in the resin 20 if the number of irradiation of pulse-shape laser beam is reduced. Therefore, occurrence of undercut of the resin 20 which forms an interlayer insulating resin layer can be prevented. Thus, the reliability of the connection of the via holes can be improved.

Abstract: An opening is formed in resin 20 by a laser beam so that a via hole is formed. At this time, copper foil 22, the thickness of which is reduced (to 3 &mgr;m) by performing etching to lower the thermal conductivity is used as a conformal mask. Therefore, an opening 20a can be formed in the resin 20 if the number of irradiation of pulse-shape laser beam is reduced. Therefore, occurrence of undercut of the resin 20 which forms an interlayer insulating resin layer can be prevented. Thus, the reliability of the connection of the via holes can be improved.

Abstract: Mesh holes 35a and 59a of upper solid layers 35 and upper solid layers 59 are formed to overlie on one another, so that the insulating properties of interlayer resin insulating layers 50 are not lowered. Here, the diameter of each mesh hole is preferably 75 to 300 &mgr;m. The reason is as follows. If the diameter of the mesh hole is less than 75 &mgr;m, it is difficult to overlay the upper and lower mesh holes on one another. If the diameter exceeds 300 &mgr;m, the insulating properties of the interlayer resin insulating layers deteriorate. In addition, the distance between the mesh holes is preferably 100 to 2000 &mgr;m. The reason is as follows. If the distance is less than 100 &mgr;m, the solid layer cannot function. If the distance exceeds 2000 &mgr;m, the deterioration of the insulating properties of the interlayer resin insulating film occurs.

Abstract: An opening is formed in resin by a laser beam so that a via hole is formed. Copper foil, the thickness of which is reduced to 3 &mgr;m by etching to lower the thermal conductivity, is used as a conformal mask. Therefore, an opening is formed in the resin and the number of irradiation of pulse-shape laser beam is reduced. Thus, occurence of undercut of the resin, which forms an interlayer insulating resin layer, can be prevented and the reliability of the connection of the via holes can be improved.

Abstract: Mesh holes 35a and 59a of upper solid layers 35 and upper solid layers 59 are formed to overlie on one another, so that the insulating properties of interlayer resin insulating layers 50 are not lowered. Here, the diameter of each mesh hole is preferably 75 to 300 &mgr;m. The reason is as follows. If the diameter of the mesh hole is less than 75 &mgr;m, it is difficult to overlay the upper and lower mesh holes on one another. If the diameter exceeds 300 &mgr;m, the insulating properties of the interlayer resin insulating layers deteriorate. In addition, the distance between the mesh holes is preferably 100 to 2000 &mgr;m. The reason is as follows. If the distance is less than 100 &mgr;m, the solid layer cannot function. If the distance exceeds 2000 &mgr;m, the deterioration of the insulating properties of the interlayer resin insulating film occurs.

Abstract: An opening is formed in resin 20 by a laser beam so that a via hole is formed. At this time, copper foil 22, the thickness of which is reduced (to 3 &mgr;m) by performing etching to lower the thermal conductivity is used as a conformal mask. Therefore, an opening 20a can be formed in the resin 20 if the number of irradiation of pulse-shape laser beam is reduced. Therefore, occurrence of undercut of the resin 20 which forms an interlayer insulating resin layer can be prevented. Thus, the reliability of the connection of the via holes can be improved.