JP2014232823A - Wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-size wiring board having fine and high-density wiring patterns.SOLUTION: The wiring board comprises: an insulative substrate 2 having a first through-hole 4 and a second through-hole 5; a first through-hole conductor 9 deposited on an inner wall of the first through-hole 4 with a filling resin 7 filling the inside thereof; a second through-hole conductor 10 deposited on an inner wall of the second through-hole 5 with its inside left hollow; and a surface layer conductor 11 deposited on top and bottom faces of the insulative substrate 2 and including the filling resin 7. The first through-hole conductor 9 is composed of a first plated conductor layer 6 deposited only on the inner wall of the first through-hole 4, and having a thickness of 10-20 μm. The second through-hole conductor 10 and the surface layer conductor 11 are composed of second plated conductor layers 8 deposited on the inner wall of the second through-hole 5, the top and bottom faces of the insulative substrate 2, and top and bottom faces of the filling resin 7 by a semi-additive method, and having a thickness of 10-20 μm.

Description

  The present invention relates to a wiring board having a filled through hole and a hollow through hole.

  Conventionally, as shown in FIG. 6, as a wiring board for mounting electronic components, a first through hole 24 filled with a filling resin 27 and a second through hole 25 hollow inside are provided. A wiring board 40 is known.

  The wiring substrate 40 includes an insulating substrate 22 in which a plurality of insulating layers 21 are stacked. The insulating layer 21 is made of, for example, glass-epoxy resin. The thickness of each insulating layer 21 is about 100 to 400 μm. Inner layer conductors 23 are disposed between the insulating layers 21 of the insulating substrate 22. The inner layer conductor 23 is made of, for example, copper foil. The inner layer conductor 23 has a thickness of about 12 to 18 μm.

  Through holes 24 and 25 are formed so as to penetrate the inner layer conductor 23 from the upper surface to the lower surface of the insulating substrate 22. The diameters of the through holes 24 and 25 are about 100 to 200 μm. A first plating conductor layer 26 is deposited on the inner walls of the through holes 24 and 25 and the upper and lower surfaces of the insulating substrate 22. The 1st plating conductor layer 26 consists of an electroless copper plating layer and the electrolytic copper plating layer on it, for example. The thickness of the electroless copper plating layer constituting the first plating conductor layer 26 is about 0.1 to 0.5 μm. The thickness of the first plating conductor layer 26 that combines the electroless copper plating layer and the electrolytic copper plating layer is about 10 to 20 μm on the inner walls of the through holes 24 and 25 and about 5 to 10 μm on the upper and lower surfaces of the insulating substrate 22. It is.

  The inside of the first through hole 24 to which the first plated conductor layer 26 is deposited is filled with a filling resin 27. The filling resin 27 is made of, for example, an epoxy resin. On the other hand, the inside of the second through hole 25 is not filled with the filling resin 27 but is hollow.

  A second plated conductor layer 28 is deposited on the surface of the first plated conductor layer 26 deposited on the inner wall of the second through hole 25 and the upper and lower surfaces of the insulating substrate 22 and on the upper and lower surfaces of the filling resin 27. The second plating conductor layer 28 includes, for example, an electroless copper plating layer and an electrolytic copper plating layer thereon. The thickness of the electroless copper plating layer constituting the second plating conductor layer 28 is about 0.1 to 0.5 μm. The thickness of the 2nd plating conductor layer 28 which combined the electroless copper plating layer and the electrolytic copper plating layer is about 10-20 micrometers. As a result, a first through-hole conductor 29 having a thickness of 10 to 20 μm made of the first plated conductor layer 26 is formed in the first through-hole 24, and the first through-hole 25 is in the first through-hole 25. A second through-hole conductor 30 having a thickness of 20 to 40 μm composed of the plating conductor layer 26 and the second plating conductor layer 28 is formed. Further, a surface layer conductor 31 having a thickness of 15 to 30 μm made of the first plating conductor layer 26 and the second plating conductor layer 28 is formed on the upper and lower surfaces of the insulating substrate 22. The surface layer conductor 31 is etched into a predetermined wiring pattern by a subtractive method.

  Then, an electrode of a surface mount type electronic component is connected to the surface conductor 31 on the first through hole 24 via solder, and a lead of the lead insertion type electronic component is inserted into the second through hole 25. At the same time, it is connected to the second through-hole conductor 30 and its surrounding surface layer conductor 31 via solder.

  Here, a method for manufacturing such a wiring board 40 will be described. First, as shown in FIG. 7A, an insulating substrate 22 having an inner layer conductor 23 is prepared. Next, as shown in FIG. 7B, through holes 24 and 25 are drilled in the insulating substrate 22. Next, as shown in FIG. 7C, the first plated conductor layer 26 is deposited on the inner walls of the through holes 24 and 25 and the upper and lower surfaces of the insulating substrate 22. The thickness of the 1st plating conductor layer 26 shall be about 10-20 micrometers. Next, as shown in FIG. 7 (d), the inside of the first through hole 24 to which the first plated conductor layer 26 is deposited is filled with a filling resin 27. Next, as shown in FIG. 8E, the upper and lower ends of the filling resin 27 are polished and flattened together with the first plated conductor layers 26 on the upper and lower surfaces of the insulating substrate 22. At this time, the first plated conductor layers 26 on the upper and lower surfaces of the insulating substrate 22 are polished to a thickness of about 5 to 10 μm. Next, as shown in FIG. 8 (f), second surfaces are formed on the inner surface of the second through-hole 25 and the surface of the first plated conductor layer 26 deposited on the upper and lower surfaces of the insulating substrate 22 and the upper and lower surfaces of the filling resin 27. The plated conductor layer 28 is deposited. The thickness of the 2nd plating conductor layer 28 shall be about 10-20 micrometers. Finally, as shown in FIG. 8 (g), the first plating conductor layer 26 and the second plating conductor layer 28 on the upper and lower surfaces of the insulating substrate 22 are etched into a predetermined wiring pattern by a subtractive method, so that the surface layer conductor 31 is obtained. As a result, the wiring board 40 is completed.

  However, according to this wiring board 40, when the surface layer conductor 31 is formed, the first plating conductor layer 26 having a thickness of about 5 to 10 μm and the second thickness of about 10 to 20 μm on the upper and lower surfaces of the insulating substrate 22 are formed. There are two plated conductor layers with the plated conductor layer 28. The total thickness of the first plating conductor layer 26 and the second plating conductor layer 28 deposited on the upper and lower surfaces of the insulating substrate 22 is about 15 to 30 μm. When the first plating conductor layer 26 and the second plating conductor layer 28 having a total thickness of 15 to 30 μm are etched into a predetermined wiring pattern by a subtractive method, the minimum width and the minimum interval of the etched wiring pattern are as follows: The limit was about 50 μm. Therefore, it is difficult to miniaturize the wiring board 40 without further miniaturization and higher density of the wiring pattern.

Japanese Patent Laid-Open No. 10-41605

  In the present invention, a wiring board having a first through hole filled with a filling resin and a second through hole hollow inside, the minimum width and the minimum interval of the wiring pattern is set to 35 μm or less, for example. An object of the present invention is to provide a small wiring board having a fine and high-density wiring pattern.

  The wiring board of the present invention is a cylindrical substrate attached to the insulating substrate having the first and second through holes and the inner wall of the first through hole, and the inside thereof is filled with a filling resin. On the inner wall of the second through hole, and on the upper and lower surfaces of the insulating substrate including the filling resin A wiring board comprising a surface layer conductor deposited so as to be electrically connected to the first through-hole conductor and the second through-hole conductor, wherein the first through-hole conductor comprises: It consists of a first plated conductor layer having a thickness of 10 to 20 μm deposited only on the inner wall of the first through-hole, and the second through-hole conductor and the surface layer conductor comprise the inner wall of the second through-hole and Said insulation Thickness deposited at upper and lower surfaces and a semi-additive method on the upper and lower surfaces of the filled resin plate is characterized in that comprising a second plating conductor layer 10 to 20 [mu] m.

  According to the wiring board of the present invention, the first plating conductor layer is attached only to the inner wall of the first through hole, whereby the surface conductors on the upper and lower surfaces of the insulating substrate are formed only by the second plating conductor layer. Has been. Since the second plating conductor layer forming the surface layer conductor is as thin as 10 to 20 μm and is deposited semi-additively, for example, a wiring pattern having a minimum width and a minimum interval of 35 μm or less can be formed. Therefore, it is possible to provide a small wiring board having a dense and high-density wiring pattern.

FIG. 1 is a schematic sectional view showing an embodiment of a wiring board according to the present invention. FIG. 2 is a schematic cross-sectional view for each step for explaining an example of the method of manufacturing the wiring board shown in FIG. FIG. 3 is a schematic cross-sectional view for each step for explaining an example of the method of manufacturing the wiring board shown in FIG. FIG. 4 is a schematic cross-sectional view for each step for explaining another example of the method for manufacturing the wiring board shown in FIG. FIG. 5 is a schematic cross-sectional view for each step for explaining another example of the method for manufacturing the wiring board shown in FIG. FIG. 6 is a schematic cross-sectional view showing a conventional wiring board. FIG. 7 is a schematic cross-sectional view for each step for explaining the method of manufacturing the wiring board shown in FIG. FIG. 8 is a schematic cross-sectional view for each step for explaining the method of manufacturing the wiring board shown in FIG.

  Next, an example of an embodiment of the wiring board of the present invention will be described with reference to FIG. As shown in FIG. 1, the wiring board 20 of the present invention includes an insulating substrate 2 in which a plurality of insulating layers 1 are laminated. The insulating layer 1 is made of, for example, an electrically insulating material in which a glass cloth is impregnated with a thermosetting resin such as an epoxy resin or a bismaleimide triazine resin. The thickness of each insulating layer 1 is about 100 to 400 μm.

  Inner layer conductors 3 are disposed between the insulating layers 1 of the insulating substrate 2. The inner layer conductor 3 is made of, for example, copper foil. The thickness of the inner layer conductor 3 is about 12 to 18 μm. The inner layer conductor 3 is etched into a predetermined wiring pattern by a subtractive method.

  A first through hole 4 and a second through hole 5 are formed from the upper surface to the lower surface of the insulating substrate 2 so as to penetrate the inner layer conductor 3. These through holes 4 and 5 have a diameter of about 100 to 200 μm.

  A first plated conductor layer 6 is attached to the inner wall of the first through hole 4. The 1st plating conductor layer 6 consists of an electroless copper plating layer and the electrolytic copper plating layer on it, for example. The thickness of the electroless copper plating layer constituting the first plating conductor layer 6 is about 0.1 to 0.5 μm. The thickness of the 1st plating conductor layer 6 which combined the electroless copper plating layer and the electrolytic copper plating layer is about 10-20 micrometers. The first plated conductor layer 6 forms a cylindrical first through-hole conductor 9. The first plated conductor layer 6 is attached only to the inner wall of the first through hole 4, and is not attached to the inner wall of the second through hole 5 and the upper and lower surfaces of the insulating substrate 2.

  Further, the inside of the first through hole 4 to which the first plated conductor layer 6 is deposited is filled with a filling resin 7. The filling resin 7 is made of a thermosetting resin such as an epoxy resin.

  A second plated conductor layer 8 is deposited on the inner wall of the second through hole 5, the upper and lower surfaces of the insulating substrate 2, and the upper and lower surfaces of the filling resin 7. The second plating conductor layer 8 includes, for example, an electroless copper plating layer and an electrolytic copper plating layer thereon. The thickness of the electroless copper plating layer constituting the second plating conductor layer 8 is about 0.1 to 0.5 μm. The thickness of the 2nd plating conductor layer 8 which combined the electroless copper plating layer and the electrolytic copper plating layer is about 10-20 micrometers. As a result, a cylindrical second through-hole conductor 10 composed of the second plated conductor layer 8 is formed in the second through-hole 5. The inside of the second through-hole conductor 10 is not filled with the filling resin 7 and is in a hollow state. Further, a surface layer conductor 11 made of the second plated conductor layer 8 is formed on the upper and lower surfaces of the insulating substrate 2 including the filling resin 7. The surface layer conductor 11 is etched into a predetermined wiring pattern by a semi-additive method.

  As described above, according to the wiring board 20 of the present invention, the first plated conductor layer 6 is deposited only on the inner wall of the first through-hole 4. 2 plating conductor layers 8 only. Since the second plated conductor layer 8 forming the surface conductor 11 is as thin as 10 to 20 μm and is semi-additively deposited, for example, a wiring pattern having a minimum width and a minimum interval of 35 μm or less may be formed. it can. Therefore, it is possible to provide a small wiring board 20 having a dense and high-density wiring pattern.

  According to this wiring board 20, the electrode of the surface mount type electronic component is connected to the surface layer conductor 11 on the first through hole 4 via solder, and the lead insertion type is connected to the second through hole 5. The lead of the electronic component is inserted and connected to the second through-hole conductor 10 and the surrounding surface layer conductor 11 via solder.

  Next, an example of a method for manufacturing the above-described wiring board 20 will be described. First, as shown in FIG. 2A, an insulating substrate 2 having an inner layer conductor 3 is prepared. Such an insulating substrate 2 has a central layer in which inner layer conductors 3 are formed on both sides by etching a copper foil of a double-sided copper-clad plate with copper foils for inner layer conductors 3 on both sides by a subtractive method. An insulating substrate in which a prepreg and a copper foil to be the upper and lower insulating layers 1 are laminated on the upper and lower surfaces of the insulating layer 1 and the prepreg is cured and a copper foil is laminated on the surface. 2 and finally, the upper and lower copper foils are removed by etching.

  Next, as shown in FIG. 2B, a first through hole 4 is drilled in the insulating substrate 2. Drilling, laser processing, or blasting is used for drilling the first through hole 4. In addition, after drilling the through hole 4, it is preferable to desmear the inner wall of the through hole 4.

  Next, as shown in FIG. 2C, the first plated conductor layer 6 is deposited on the inner wall of the first through hole 4 and the upper and lower surfaces of the insulating substrate 2. In order to deposit the first plating conductor layer 6, an electroless copper plating layer having a thickness of about 0.1 to 0.5 μm is deposited on the inner wall of the first through hole 4 and the upper and lower surfaces of the insulating substrate 2. Thereafter, a method of depositing an electrolytic copper plating layer thereon is employed. The thickness of the 1st plating conductor layer 6 shall be about 10-20 micrometers.

  Next, as shown in FIG. 2D, the inside of the first through hole 4 to which the first plating conductor layer 6 is deposited is filled with a filling resin 7. In order to fill the filling resin 7 inside the first through hole 4, a method is adopted in which a resin paste made of an uncured epoxy resin is pushed into the first through hole 4 by a screen printing method and thermally cured. Is done.

  Next, as shown in FIG. 3E, the upper and lower ends of the filling resin 7 are polished and flattened together with the first plated conductor layers 6 on the upper and lower surfaces of the insulating substrate 2. For polishing, a roll polishing machine or a belt polishing machine is used. At this time, the first plated conductor layers 6 on the upper and lower surfaces of the insulating substrate 2 are polished to a thickness of about 5 to 10 μm.

  Next, as shown in FIG. 3 (f), the first plated conductor layer 6 on the upper and lower surfaces of the insulating substrate 2 is removed by etching, leaving the first plated conductor layer 6 only on the inner wall of the first through hole 4. . As a result, a first through-hole conductor 9 composed of the first plated conductor layer 6 is formed in the first through-hole 4.

  Next, as shown in FIG. 3G, the second through hole 5 is drilled in the insulating substrate 2. As with the case of the first through hole 4, drilling, laser processing, or blasting is used for drilling the second through hole 5. In addition, after drilling the through hole 5, it is preferable to desmear the inner wall of the through hole 5.

  Finally, as shown in FIG. 3 (h), the second plated conductor layer 8 is deposited on the inner wall of the second through hole 5, the upper and lower surfaces of the insulating substrate 2, and the upper and lower surfaces of the filling resin 7. In order to deposit the second plating conductor layer 8, the electroless copper plating having a thickness of about 0.1 to 0.5 μm on the inner wall of the second through hole 5, the upper and lower surfaces of the insulating substrate 2, and the upper and lower surfaces of the filling resin 7. After depositing a layer, a plating resist layer having an opening pattern corresponding to the wiring pattern of the surface conductor is formed on the electroless copper plating layer, and then the electroless copper plating layer in the opening pattern of the plating resist layer After the electrolytic copper plating layer is deposited thereon, a semi-additive method is employed in which the plating resist layer and the underlying electroless copper plating layer are removed. Thereby, the wiring board 20 shown in FIG. 1 is completed.

  In addition, the manufacturing method of the wiring board 20 is not restricted to the above-mentioned example, There exist various methods. An example of such a method is described below. For example, as shown in FIG. 4A, an insulating substrate 2 having an inner layer conductor 3 is prepared. Next, as shown in FIG. 4B, the first through hole 4 and the second through hole 5 are drilled in the insulating substrate 2. Next, as shown in FIG. 4C, the first plated conductor layer 6 is deposited on the inner wall of the first through hole 4, the inner wall of the second through hole 5, and the upper and lower surfaces of the insulating substrate 2. Next, as shown in FIG. 4D, the inside of the first through hole 4 to which the first plated conductor layer 6 is deposited is filled with a filling resin 7. Next, as shown in FIG. 5E, the upper and lower ends of the filling resin 7 are polished and flattened together with the first plated conductor layers 6 on the upper and lower surfaces of the insulating substrate 2. Next, as shown in FIG. 5 (f), the inner wall of the second through-hole 5 and the first plated conductor layer 6 on the upper and lower surfaces of the insulating substrate 2 are removed by etching, and only the inner wall of the first through-hole 4 is removed. 1 plating conductor layer 6 is left. Finally, as shown in FIG. 3G, the second plated conductor layer 8 is deposited on the inner wall of the second through hole 5, the upper and lower surfaces of the insulating substrate 2, and the upper and lower surfaces of the filling resin 7. Also by this, the wiring board 20 shown in FIG. 1 can be obtained.

DESCRIPTION OF SYMBOLS 2 ... Insulating substrate 4 ... 1st through-hole 5 ... 2nd through-hole 6 ... 1st plating conductor layer 7 ... Filling resin 8 ... 2nd plating conductor layer 9... First through-hole conductor 10... Second through-hole conductor 11.

Claims (1)

  An insulating substrate having first and second through-holes, a first through-hole conductor that is cylindrically attached to the inner wall of the first through-hole, and whose inside is filled with a filling resin; A second through-hole conductor that is cylindrically attached to the inner wall of the second through-hole and has a hollow inside, and the first through-hole conductor on the upper and lower surfaces of the insulating substrate including the filling resin And a surface layer conductor deposited so as to be electrically connected to the second through-hole conductor, wherein the first through-hole conductor is an inner wall of the first through-hole. A first plated conductor layer having a thickness of 10 to 20 μm deposited only on the first and second surface layers, and the second through-hole conductor and the surface layer conductor include inner walls of the second through-hole, upper and lower surfaces of the insulating substrate, and Previous Wiring board thickness deposited at a semi-additive method on the upper and lower surfaces of the filling resin is characterized in that it consists of the second plating conductor layer 10 to 20 [mu] m.

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