JP4483069B2 - Printed wiring board and manufacturing method thereof - Google Patents

Description

[0001]
【Technical field】
The present invention relates to a printed wiring board used for mounting electronic parts and the like and a method for manufacturing the same.
[0002]
[Prior art]
On the printed wiring board, conductor circuits are formed in layers. Electrical conduction between the layers is performed through a via hole covered with metal plating or a via hole filled with a conductive material. The periphery of the via hole is surrounded by a land, and the via hole and the conductor circuit are connected via this land.
[0003]
[Problems to be solved]
However, in the conventional via hole, a connection failure may occur between the via hole and the land surrounding the via hole.
[0004]
In view of the conventional problems, the present invention intends to provide a printed wiring board excellent in connection reliability between a via hole and a conductor circuit, and a manufacturing method thereof.
[0005]
[Means for solving problems]
The invention of claim 1 is a printed wiring board having an insulating substrate, a buried via formed by embedding a conductive material in a hole provided in the insulated substrate, and a metal layer bonded to the opening peripheral edge of the buried via. ,
The upper end and the lower end of the joint portion of the metal layer that is joined to the buried via enter the inside along the inner wall of the buried via,
The thickness of the joint portion is much larger than the thickness of the other general portion of the metal layer,
And the thickness t of the said general part in the said metal layer is 4-70 micrometers, and the thickness T of the said junction part is at least 5 micrometers, It is a printed wiring board characterized by the above-mentioned .
[0006]
In the present invention, the buried via is joined to the metal layer at the peripheral edge of the opening. The thickness T of the junction with the buried via in the metal layer is larger than the thickness t of the other general part. For this reason, the contact area between the metal layer and the buried via is increased, and the bonding strength between the two is increased. Therefore, the connection reliability between the two is increased and the conductivity is improved.
[0007]
The ratio (T / t) between the thickness T of the joint in the metal layer and the thickness t of the other general part is preferably greater than 1 and does not exceed the thickness of the insulating substrate. If it is less than 1, the thickness T of the joint portion between the metal layer and the buried via becomes small, and the connection reliability with the buried via may be lowered. In addition, when the thickness T of the bonded portion exceeds the thickness of the insulating substrate, the bonded portion exceeding the insulating substrate becomes a protrusion, which is easily detached and may cause a defect such as a short circuit.
[0008]
In the present invention, the thickness T of the joint portions in the metal layer is Ru least 5μm der. If it is less than 5 μm, the connection reliability with the buried via may be lowered.
[0009]
Further, the other general part in the metal layer refers to a part of the metal layer that is not joined to the buried via. The thickness t of this general part, Ru 4~70μm der. If the thickness is less than 4 μm, the strength of the metal layer may be reduced, and if it exceeds 70 μm, it may be difficult to form fine wiring.
[0010]
Further, upper and lower ends of the joint portions in the metal layer, that have entered the inside along the inner wall of the buried vias. As a result, the contact area between the metal layer and the conductive material in the embedded via is increased, and the bonding strength between the junction of the metal layer and the embedded via is further increased.
The metal layer has various shapes such as a wiring pattern, a pad, and a land.
The conductive material embedded in the embedded via is, for example, copper, aluminum, nickel, solder or the like.
[0011]
For the insulating substrate, a thermosetting resin such as epoxy resin, phenol resin, bismaleimide torazine resin, polyphenylene resin, polyphenylene ether resin, polyimide resin, or a mixture thereof can be used. The insulating substrate may contain a reinforcing material such as glass cloth or inorganic filler.
The hole provided in the insulating substrate is, for example, a punching hole described later. In addition, it may be a hole formed by a drill, a laser, or the like.
[0012]
Next, the invention of claim 2 is a method of manufacturing the printed wiring board of claim 1.
That is, the present invention is a printed wiring board having an insulating substrate, an embedded via formed by embedding a conductive material in a hole provided in the insulating substrate, and a metal layer bonded to the peripheral edge of the opening of the embedded via, The upper end and the lower end of the joint portion of the metal layer that is joined to the buried via enter the inside along the inner wall of the buried via,
The thickness of the joint is larger than the thickness of the other general part in the metal layer,
In the method of manufacturing a printed wiring board, the thickness t of the general part in the metal layer is 4 to 70 μm, and the thickness T of the joint is at least 5 μm.
A step of laminating a conductive material on the insulating substrate to which a metal layer having a thickness t of 4 to 70 μm is bonded via the metal layer;
The insulating substrate, the metal layer, and the conductive material are punched, and a punched piece formed by punching the conductive material is embedded in a punched hole formed in the insulating substrate and the metal layer. Including the step of causing the opening peripheral edge of the punched hole to enter along the inner wall of the punched hole of the insulating substrate to form the bonded portion, and bonding the bonded portion and the punched piece of the conductive material. It is the manufacturing method of the printed wiring board characterized .
[0013]
In this manufacturing method, a conductive material is coated on a metal layer bonded to an insulating substrate , and these predetermined portions are locally punched from above by punching or the like. At this time, since the ductility of the metal layer is large, the punched portion of the metal layer is stretched in a bow shape and enters the punched hole of the insulating substrate. The thickness of the entrance portion of the metal layer is larger than the thickness of other general portions. Further, the punching piece of the conductive material is embedded in the punching hole of the insulating substrate by the pressing force from above.
[0014]
The punched piece of the conductive material is joined to the entry portion of the metal layer in the punched hole of the insulating substrate. The joining thickness between the entry portion and the conductive material in the punched hole is larger than the thickness of the other general portion of the metal layer. For this reason, according to this manufacturing method, the printed wiring board excellent in the connection reliability between a via hole and a conductor circuit can be obtained.
Moreover, since the embedded via can be formed by a simple operation of punching, the productivity is high.
For the metal layer disposed on the coated side of the conductive material, the thickness T of the junction between the conductive material, not larger than the other general portion of the thickness t. This improves the connection reliability between the metal layer and the buried via.

[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1
A printed wiring board and a manufacturing method thereof according to an embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, the printed wiring board of this example includes an insulating substrate 8 and embedded vias 6 in which a conductive material 7 is embedded in a punched hole 80 provided in the insulating substrate 8. A metal layer 5 is bonded to the peripheral edge of the opening of the buried via 6. The thickness T of the joint portion 51 joined to the buried via 6 in the metal layer 5 is 35 μm, the thickness t of the other general portion 52 is 18 μm, and T is larger than t.
[0016]
An upper end 511 and a lower end 512 of the joint portion 51 in the metal layer 5 enter the embedded via 6. The upper end 511 of the joint portion 51 is at a position lower than the surface of the general portion 52 of the metal layer 5.
As shown in FIG. 2, the metal layer 5 includes lands 55 and wiring patterns 56. The land 55 surrounds the embedded via 6.
[0017]
Next, the manufacturing method of the printed wiring board of this example is demonstrated.
First, as shown in FIG. 3A, a glass epoxy substrate having a thickness of 80 μm is prepared as the insulating substrate 8, and a copper foil having a thickness of 18 μm as the metal layer 5 is bonded to one side.
Next, a copper foil having a thickness of 98 μm as the conductive material 7 is disposed on the metal layer 5.
[0018]
Next, as shown in FIG. 3B, the insulating substrate 8 in which the metal layer 5 and the conductive material 7 are stacked is placed on the die 31. The die 31 has a guide hole 30 having a diameter of 155 μm. Opposing to this, the upper punch 33 for punching is arranged on the conductive material 7 so as to be movable in the vertical direction. In the stage before punching, the upper punch 33 is disposed above the die 31. The diameter of the upper punch 33 is 145 μm, and the clearance from the die 31 is 5 μm on one side.
[0019]
Here, if the clearance between the die 31 and the upper punch 33 is reduced, the thickness T of the joined portion, which is a thick portion of the metal layer 5, is reduced, so at least the clearance needs to be 2 μm on one side. On the contrary, if the clearance is large, the insulating substrate 8 is likely to be deformed, and the metal layer 5 is cut without extending, and T cannot be increased. Even if the clearance is large, it is preferably 30 μm on one side. This method utilizes elongation of the metal layer, and preferably has high ductility and relatively low hardness. Among these metals, copper, solder, and gold are preferable.
[0020]
Next, as shown in FIG. 4C, the upper punch 33 is moved downward to press the punched portions of the metal layer 5, the conductive material 7 and the insulating substrate 8. Then, as shown in FIG. 4 (d), cylindrical punching holes 50, 70, 80 are formed in the punched portion, and cylindrical punching pieces 501, 701, 801 are punched therefrom.
At this time, the peripheral edge portion of the punched hole 50 in the metal layer 5 extends due to the pressure from above and slightly enters the guide hole 30. The punched piece 701 of the conductive material 7 is embedded in the punched hole 80 of the insulating substrate 8 and joined to the entry portion of the metal layer 5.
As a result, the buried via 6 is formed by embedding the punched piece 701 of the conductive material 7.
Thereafter, the conductive material 7 on the insulating substrate 8 is removed and a pattern is formed on the metal layer 5.
Thus, the printed wiring board shown in FIGS. 1 and 2 is obtained.
[0021]
In this example, as shown in FIG. 4C, the insulating substrate 8 is covered with the metal layer 5 and the conductive material 7 and punched out from above with the upper punch 33 or the like. At the time of punching, the opening peripheral edge of the punching hole 80 is deformed into a taper shape by the pressure from above. Further, the metal layer 5 is stretched by the clearance between the die 31 and the upper punch 33 and enters the inside along the inner wall of the punching hole 80. Therefore, the thickness of the entrance portion is larger than the thickness of other general portions.
[0022]
And the said approach part of this metal layer 5 joins with the punching piece 701 of the electrically-conductive material 7 in the punching hole 80, and forms the junction part 51. FIG. Thus, the thickness T of the joint portion 51 formed from the entry portion is larger than the thickness t of the other general portion 52 of the metal layer 5. For this reason, according to this manufacturing method, the printed wiring board excellent in the connection reliability between the embedded via | veer 6 and the metal layer 5 can be obtained.
Further, since the buried via 6 can be formed by a simple operation of punching the conductive material 7, the productivity is high.
[0023]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the printed wiring board excellent in the connection reliability between a via hole and a conductor circuit, and its manufacturing method can be provided.
[Brief description of the drawings]
1 is a cross-sectional view of a printed wiring board according to Embodiment 1;
FIG. 2 is a perspective view of a printed wiring board for showing the periphery of a buried via according to the first embodiment.
FIGS. 3A and 3B are explanatory views (a) to (b) for illustrating a method for manufacturing a printed wiring board in Embodiment 1. FIG.
4A to 4D are explanatory views (c) to (d) for illustrating a method for manufacturing a printed wiring board following FIG. 3;
[Explanation of symbols]
30. . . Guide holes,
31. . . Die,
33. . . Top punch,
5). . . Metal layer,
50, 70, 80. . . Punching holes,
51. . . Joint,
52. . . General Department,
501,701,801. . . Punched piece,
511. . . Top,
512. . . lower end,
6). . . Buried vias,
7). . . Conductive material,
8). . . Insulating substrate,

Claims (2)

A printed wiring board having an insulating substrate, an embedded via formed by embedding a conductive material in a hole provided in the insulating substrate, and a metal layer bonded to an opening peripheral edge of the embedded via,
The upper end and the lower end of the joint portion of the metal layer that is joined to the buried via enter the inside along the inner wall of the buried via,
The thickness of the joint portion is much larger than the thickness of the other general portion of the metal layer,
In the printed wiring board, the thickness t of the general portion in the metal layer is 4 to 70 μm, and the thickness T of the joint portion is at least 5 μm . A printed wiring board having an insulating substrate, an embedded via formed by embedding a conductive material in a hole provided in the insulating substrate, and a metal layer bonded to the peripheral edge of the opening of the embedded via, wherein the embedded in the metal layer The upper and lower ends of the joint joined to the via enter the interior along the inner wall of the embedded via,
  The thickness of the joint is larger than the thickness of the other general part in the metal layer,
  In the method of manufacturing a printed wiring board, the thickness t of the general part in the metal layer is 4 to 70 μm, and the thickness T of the joint is at least 5 μm.
  A step of laminating a conductive material on the insulating substrate to which a metal layer having a thickness t of 4 to 70 μm is bonded via the metal layer;
  The insulating substrate, the metal layer, and the conductive material are punched, and a punched piece formed by punching the conductive material is embedded in a punched hole formed in the insulating substrate and the metal layer. Including the step of causing the opening peripheral edge of the punched hole to enter along the inner wall of the punched hole of the insulating substrate to form the bonded portion, and bonding the bonded portion and the punched piece of the conductive material. A method for producing a printed wiring board.

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