JP2000133914A - Printed wiring board and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase density and definition in the widths of circuit conductors on the surface of a printed wiring for ensuring the thickness of a copper plating on a through hole part having an electrical reliability in connection, while for raising the mounting density of electronic components. SOLUTION: Resists 3 for plating are formed on a base material 1 for printed wiring board bored a hole 2 for through hole to apply a first copper plating to a through hole part and surface circuit conductor parts, thereby increasing density and definition in first layer circuit conductors 5. After that, after resists 6 for plating, which is also used in combination as solder, are formed on a printed wiring board surface other than the through hole part and pads for electronic component mounting on the surface circuit conductor parts, a second copper plating is applied to the through hole part and the pads for electronic component mounting. As this result, the conductors 5 are formed into a fine wire by the first copper plating, the through hole part and the pads for electronic component mounting are formed by the second copper plating, the electrical reliability in connection of the through hole part is ensured, while a mounting density of electronic components can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a printed wiring board having through holes and a method for manufacturing the same.

[0002]

2. Description of the Related Art A conventional printed wiring board will be described with reference to FIG. As shown in FIG. 2A, a specified through-hole 2 is drilled at a predetermined position in a base material 1 of a printed wiring board by drilling. Next, FIG.
As shown in FIG.
Is formed on both surfaces of the substrate 1. Further, as shown in FIG. 2 (c), the exposed portion of the substrate 1 other than the portion covered with the plating resist 3 is plated with copper, and the through-hole portion conductor 4 and the first surface circuit conductor 5 are formed. Form. (The above is referred to as Conventional Example 1.)

A printed wiring board according to another conventional method different from the conventional example 1 will be described with reference to FIG. FIG.
As shown in (a), a specified through-hole 2 is drilled at a predetermined position in a copper-clad laminate by drilling. An etching resist 12 is formed on the copper foil 11 of the copper-clad laminate 10 as shown in FIG. 3B, and a circuit conductor 13 is formed by etching as shown in FIG. Then, the etching resist 12 is removed, and a resist 6 for soldering and plating is formed on the exposed portion of the base material surface shown in FIG. 3D, and then copper plating is performed. Hall portion conductor 24 and surface circuit portion conductor 2 of conventional example 2
5 is formed. This is a manufacturing method in which the subtractive method and the additive method are mixed. (The above is referred to as Conventional Example 2.)

[0004]

In the above-mentioned conventional example, as shown in FIG. 2, in the conventional example 1, the through-hole portion and the surface circuit conductor portion of the printed wiring board are simultaneously plated with copper, so that the through-hole is formed. The conductor thickness required to ensure the electrical connection reliability of the hole will be formed in both the through-hole and the surface circuit conductor, so that the plating thickness is approximately the same as the thickness of the surface circuit conductor. It is necessary to have the formation precision of the resist for plating and the formation precision of the surface circuit conductor, and to form the high-density, high-precision circuit conductor width and circuit conductor spacing of 100 μm or less. Is difficult to do. Further, in the conventional example 2, in addition to the formation accuracy of the etching resist for forming the positive pattern, the accuracy of etching for the conductor thickness is required at the time of forming the circuit conductor portion, and the conductor width accuracy of the surface circuit with higher definition is obtained. Is difficult. An object of the present invention is to enable formation of a high-density, high-precision, thinned surface circuit conductor, and furthermore, a through-hole conductor necessary for securing electrical connection reliability of the through-hole portion. This is to obtain the thickness. Further, by mainly forming the connection pads of the electronic component by the second copper plating, it is possible to arrange the connection pads of the predetermined electronic component with more flexibility.

[0005]

In order to achieve the above-mentioned object, the present invention relates to a substrate for a printed wiring board as shown in FIG.
Then, holes 2 for through holes are drilled, and a resist 3 for plating in the form of a negative pattern
After that, first, after forming the through-hole portion conductor 4 and the first surface circuit conductor 5 by the first copper plating,
A resist 6 for soldering and plating is formed on the upper surface, and a second copper plating is applied to an exposed portion other than the resist coating portion, and a second through-hole conductor 7 and a second surface are formed. The circuit conductor 8 is formed, and the thickness of the through-hole conductor necessary for electrical connection reliability of the through-hole is secured.
In addition, there is provided a printed wiring board and a method for manufacturing the same, wherein the second surface circuit conductor 8 is provided mainly with a connection pad portion for mounting an electronic component.

In a printed circuit board, a through-hole conductor formed by first copper plating, a surface circuit conductor formed on a substrate, a solder / plating resist formed on the upper surface of the surface circuit conductor, A printed wiring board comprising a second through-hole conductor formed by a second copper plating and connection pads for electronic components.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to FIG. At a predetermined position of the base material 1 shown in FIG.
Drilling or laser drilling. A resist 3 for plating is formed on the surface of the substrate 1 shown in FIG. A first electroless copper plating is applied to a portion where the resist is not formed in FIG.
And a through hole conductor 4 are formed. Further, FIG.
In (d), a resist 6 for soldering and plating is formed on the resist 3 for plating and the upper surface of the first surface circuit conductor 5, and then a second electroless copper plating is performed.
(E) The second through-hole conductor 7 and the second surface circuit conductor 8 are formed.

An embodiment of the present invention will be described specifically.
After drilling holes 2 for through holes in the base material 1 (trade name: LE-168 of Hitachi Chemical Co., Ltd.) which is a laminated board with an adhesive, a dry film photoresist (thickness: 15 μm) is formed on both surfaces of the base material 1 Product name of Hitachi Chemical Co., Ltd., S
R-3000). Next, the dry film is baked and developed to form both sides as a resist 3 for plating in a negative pattern. Then, a 15 μm-thick first electroless copper plating is performed on the exposed portion other than the coating portion of the plating resist 3 to thereby obtain a conductor thickness of 15 μm.
By forming the through-hole conductor 4 of 1 μm and the first surface circuit conductor 5, the first purpose is to reduce the thickness of the circuit conductor, and to achieve the plating resist 3 and the first surface circuit conductor 5. The thickness becomes the same, and the surface of the printed wiring board becomes flat. Thereafter, a dry film for soldering and plating is brought into close contact with the entire flat surface, and then the dry film is baked and developed to form a 15 μm thick resist 6 for soldering and plating. After that, the second through-hole portion conductor 7 and the second surface circuit conductor 8 are formed by applying a second electroless copper plating of 15 μm thickness to the exposed portion not covered with the solder / plating resist 6. Form. As a result, the total conductor thickness of the through-hole conductor including the through-hole conductor 4 and the second through-hole conductor 7 is 3
A conductor layer having a thickness of 0 μm can be formed. Therefore,
While the electrical connection reliability of the through-hole portion is ensured, the second surface circuit conductor 8 on the surface of the printed wiring board is formed mainly with a pad for connecting electronic components, thereby forming a conductor. There is no general wiring circuit conductor on the surface, and short-circuit failure and soldering failure can be reduced.

[0009]

As described above, according to the present invention, in a circuit conductor of a printed wiring board having a through hole, the circuit conductor width accuracy and thinning can be significantly improved, and the electrical connection reliability of the through hole portion can be improved. Performance can be improved. By mounting the printed wiring board according to the present invention, in which the width of the circuit conductor is reduced, it is possible to meet the demand for higher density and smaller electronic application equipment.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a procedure of a manufacturing method of the present invention.

FIG. 2 is a schematic sectional view showing a procedure for manufacturing Conventional Example 1.

FIG. 3 is a schematic cross-sectional view showing a procedure for manufacturing Conventional Example 2.

[Explanation of symbols]

 1: Base material 2: Hole for through hole 3: Resist for plating 4: Conductor for through hole 5: First surface circuit conductor 6: Resist for solder and plating 7: Conductor for second through hole 8: Second Second surface circuit conductor 10: Copper-clad laminate 11: Copper foil 12: Etching resist 13: Circuit conductor 24: Through-hole conductor of Conventional Example 2 25: Surface circuit conductor of Conventional Example 2.

Claims (2)

[Claims] In a printed wiring board, a through-hole conductor formed by a first copper plating, a first surface circuit conductor formed on a base material, and solder / plating formed on an upper surface of the surface circuit conductor. A printed wiring board, comprising: a resist for use in a semiconductor device, a second through-hole conductor formed by a second copper plating, and a connection pad for an electronic component. 2. In a printed wiring board, a plating resist is formed on a surface of a base material having a hole for through hole formed therein,
Apply the first copper plating to the exposed parts other than this resist,
Forming a general surface circuit conductor and through-hole conductor on the base material, and then forming a resist for soldering and plating on the surface except for the through-hole and connection pads for electronic components, A method for manufacturing a printed wiring board, comprising: applying a second copper plating to an exposed portion other than a resist forming portion to form a connection pad between a second through-hole portion conductor and an electronic component.