JP2000031644A - Circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deterioration in anti-electrocorrosion property and reliability of electrical connection for a via hole, when in use under high- temperature and high-humidity high electric field environment in a circuit board having both faces or a multilayer interconnections. SOLUTION: A nickel plated films 9, 10 is formed on an inner wall of a through-hole 8. In order to protect a copper plated films 11, 12 of a via hole 17, in the hole 17 an organic insulator 13 is formed. By covering the inner wall of the through-hole 8 with the base nickel plated films 9, 10 and applying a copper plating solution thereto, a copper plating solution does not permeat inside through the inner wall of the hole 8 and thereby anti-electrocorrosion property at high-temperature and high-humidity high electric field can be improved. By filling the via hole with the organic insulator 13 made of modified epoxy resin, barrel cracks due to fatigue of the metal plated films 11, 12 can be prevented to give a circuit board 27 which is superior in electrical connection reliability, having great effect in contributing to the industry.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrical connection characteristic of a via connection hole in a high-temperature, high-humidity, high-field environment relating to a circuit board.

[0002]

2. Description of the Related Art In recent years, further improvements in electrical connection reliability have been demanded in a high-temperature, high-humidity, high-electric-field environment accompanying multifunctional use of electronic devices. A manufacturing method or the like of coating a nickel plating film thereon is used, and is manufactured by the following manufacturing process. Hereinafter, a manufacturing process according to a conventional technique will be described with reference to FIG.

First, as a conventional circuit wiring board 38, as shown in FIG. 5, a copper-clad glass laminated board composed of a front and back copper foil 29 and an insulating substrate 28 is used, and is selectively penetrated by a drill. A hole 30 is formed, and the through hole 30 is formed.
A conductive connection hole 32 formed from a base copper plating film 31 by simultaneously performing chemical plating and electrolytic copper plating on the inner wall and the front and back.
Then, the via connection hole 36 formed by coating the nickel plating film 34 by dipping in the electrolytic plating solution is formed on the base.

Then, using a photosensitive dry film, a conductive connection hole land 37 and an outer layer land formed through exposure, development, etching (using an iron chloride solution or an ammonium persulfate solution) and a stripping process, and then screen printing. A circuit board 38 according to the prior art, in which the solder resist 33 is applied and formed by the method, is obtained.

[0005]

However, in the circuit board 38 according to the prior art described above, firstly, first, along the glass fiber in the insulating substrate 28 existing on the inner wall surface of the through hole 30. In addition, the copper chemical plating solution used in performing the chemical plating treatment migrates and penetrates into the central portion, so that when used in a high-temperature, high-humidity, high-electric field environment, electrical characteristic deterioration (deterioration of electrolytic corrosion resistance) is reduced. There is a problem of getting up.

[0006] Second, after mounting the mounted components, 3
High temperature (about 180-280)
Under the environment, a compressive stress caused by a concentration of thermal stress generated on the inner wall of the through hole 30 and the copper plating film 31 is received, and a fatigue of the copper plating film 31 causes a barrel crack around the entire center of the hole due to fatigue of the copper plating film 31. There is a problem that the electrical connection reliability of the connection holes 32 and 36 is reduced.

Further, in order to prevent the occurrence of barrel cracks in the copper plating film 31, it is necessary to form the copper plating film 31 with a large thickness, but this is not suitable in the current situation where fine wiring is required. .

The present invention has been made in view of the above circumstances, and an object of the present invention is to prevent deterioration of characteristics in a high-temperature, high-humidity, high-electric-field environment, or to provide a via hole 16.
・ Circuit board 2 with better electrical connection reliability of 17
7 is provided.

[0009]

According to the present invention, an inner copper foil 1 is provided.
A via connection hole 17 electrically connected to the inner conductors 3, 4 using a double-sided or multi-layer organic copper-clad laminate 7 composed of organic insulation layers 5, 6 and inner conductors 3, 4; ,
In the circuit board having the outer layer lands 24 and 25, the thickness of the base metal film of the entire front and back surfaces and the conductive connection holes 16 is 0.6.
Direct electrolytic nickel plating film 9 in the range of 12 μm
And via holes 17 formed by covering the surfaces of the base nickel plating films 9 and 10 with electrolytic copper plating films 11 and 12 having a metal film thickness of 15 to 35 μm. 17, an organic insulator 13 is formed, and an outer land 1 is formed on the organic insulator 13 by a photo-etching method.
After forming 4.15 and conductive connection lands 18 and 19,
Electroless plating permanent resists 20 and 21 are formed to have outermost layer connection pads 22 and 23 used for fixing mounted components. Further, even in a high-temperature, high-humidity, and high-field environment, the electrolytic corrosion resistance and electrical connection reliability are improved. It is intended to prevent deterioration.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a circuit board 27 according to the present invention has an inner copper foil 1 formed on organic insulating layers 5 and 6.
2, inner conductors 3 and 4, conductive connection holes 16 and 17 electrically connected to inner copper foils 1.2 and inner conductors 3.4, respectively, and filled with organic insulator 13 in holes 17;・ Form,
The outermost layer connection pads 2 are protected on the front and back surfaces of the conductive connection hole lands 18 and 19 on the holes 17 by protecting the metal plating films 11 and 12.
2 and 23 can be formed, the occupied area for mounting component fixing can be reduced, and the via connection hole 17 is provided.

The inner wall of the through hole 8 has a thickness of 0.6.
１２12 μm of the underlying nickel plating film 9.1, and the surface of this coating is covered with the electrolytic copper plating film 9.1.
2 and has a thickness of 15 to 35 μm. As described above, it is possible to prevent the deterioration of the electrical characteristics due to the penetration amount 35 of the copper plating solution under the high electric field environment of high temperature and humidity.

Further, when passing through the high reflow furnace, the copper plating film 1 at the center of the conductive connection holes 16 and 17 is formed.
1 and 12 are fatigued to prevent the occurrence of a continuous barrel crack over the entire circumference of the conductive connection hole 17, and the hole 17 is filled with the organic insulator 13 so that the copper plating films 11 and 12 can be physically protected. It is possible that the electrical connection reliability can be improved by protecting the electrical stress.

According to the above-mentioned invention, the corrosion resistance of the circuit board 27, the prevention of the amount of plating solution permeation, and the further improvement of the electrical connection reliability can be realized (see Table 1).

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a detailed description will be given based on FIGS. 2, 3 and 4 showing an embodiment of the present invention.
The thickness of the underlying nickel plating film 9/10 is about 0.6 μm.
μm, as Example 3, the base nickel plating film 9.1
0 The film thickness is about 12 μm and the subsequent manufacturing steps are the same.
It was prepared as described below by the same manufacturing method.

Example 1 First, as shown in FIG. 2, an organic copper-clad laminate 7 (trade name: MCL, manufactured by Hitachi Chemical Co., Ltd.)
-E-67S) is constructed by laminating and bonding the inner conductors 3,4, the inner copper foils 1,2 and the organic insulating layers 5,6, and selectively using a drill, and using an automatic numerical drilling machine ( Hitachi Seiko Machine)
, A through hole 8 having a hole diameter of 0.6 mm was formed by a step method.

Next, the inner wall and the upper and lower surfaces of the through hole 8 were subjected to a smear treatment, and a 0.6 μm-thick base of the nickel plating films 9 and 10 was formed by direct electrolytic plating. As a result, the migration of copper ions can be prevented by the nickel films 9 and 10. As the nickel plating method, for example, there is an electroless nickel plating method or a direct panel electrolytic nickel plating method. Although suitable, an electroless nickel plating solution may be used. The nickel plating solution may be, for example, Nippon Kanigen, Okuno Pharmaceutical or Uemura Kogyo, and is not limited to this in the present invention.

In Examples 2 and 3, the nickel plating films 9 and 10 were formed on the inner walls of the through holes 8 by the above-described manufacturing method.

Next, as shown in FIG. 3, electrolytic copper plating is performed, and metal (copper) plating films 11 and 12 are formed on the inner wall of the conductive connection hole (nickel) 16 and on the entire front and back surfaces to have a thickness of about 15 to 35.
A coating is formed in a range of μm.

Further, in order to prevent the occurrence of barrel cracks around the hole 17 due to the fatigue of the metal plating films 11 and 12 of the conductive connection holes 16 and 17 in the via connection hole 17, a modified epoxy resin is used. Organic insulator 13 consisting of
After filling and forming, the outer layer land 1 is covered with a photo-etching method (etching step: ferric chloride solution, photosensitive dry film: PHOTEC H-240).
4.15 and conductive connection hole lands 18 and 19 are formed.

Next, as shown in FIG. 4, the formation of the electroless plating permanent resists 20 and 21 (trade name: SR-3000 manufactured by Hitachi Chemical Co., Ltd.) was performed by using a vacuum laminator (Hitachi AIC Co., Ltd.). (Product name: HLM-V570), and after being fully cured, it is formed through an exposure / water-based development / peeling step.

Next, after roughening, the electroless plating solution CC
Using -41 (manufactured by Hitachi AIC Co., Ltd.), the outermost layer lands 24 and 25 and the outermost layer connection pads 22 and 23 are formed on the hole 17 to a film thickness of about 20 to 25 μm, and the corrosion resistance and electrical connection reliability are formed. Circuit board 27 of the present invention is obtained, and after applying a solder cream on the front and back of the circuit board 27 using a metal screen plate, the outermost layer connection pads 22 and 23 and the outermost land 24
A solder layer 26 having a film thickness of 70 μm is obtained on 25.

As described above, in the circuit board 27 obtained in Examples 1, 2 and 3 and the prior art example 38, the base electroless copper plating 35 and the base nickel plating 9 10 and the electrolytic corrosion of the adjacent holes 17 to 17 and the holes 36 to 36, and the connection reliability by the hot oil test were evaluated. It is shown in FIG.

The amount of the plating solution soaked in the through hole 8
30 were measured by observing the cross section of the inner wall with an optical microscope at a magnification of 400 times. For electrolytic corrosion, apply DC 50 V between the conductive connection holes 17 and 36, 85 ° C., 85%
Insulation resistance value (Ω) after standing at RH for 1000 hours.
Connection reliability (hot oil test) is 260 ° C oil 1
One cycle of immersion for 0 seconds, 15 seconds for transition, 60 seconds for immersion for 60 seconds in running water at 20 ° C, and 15 seconds for transition, measure the series resistance value of 800 holes and reject the number of cycles in which the resistance value increased by 10% or more of the initial value And

The evaluation results are shown in Table 1.

[Table 1]

As apparent from Table 1, according to the present invention, the nickel plating solutions 9 and 10 are applied to the inner walls of the through holes 8.
The circuit board 27 according to the second embodiment which can eliminate the amount of penetration, has excellent corrosion resistance under a high temperature and high humidity and high electric field, and can further improve electrical connection reliability.
Can be obtained.

[0026]

(1) According to the present invention, the inner wall of the through-hole 8 is covered with the nickel plating films 9 and 10 and the copper plating solution is applied to the through-hole. It is possible to prevent the penetration of the metal plating films 11 and 12 by filling and forming an organic insulator 13 made of a modified epoxy resin in the via connection holes 17. In addition to preventing barrel cracks due to fatigue, a circuit board 27 having excellent electrical connection reliability is obtained, and the effect of contributing to industry is extremely large.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a manufacturing process of the present invention.

FIG. 3 is a sectional view showing a manufacturing process of the present invention.

FIG. 4 is a sectional view showing a manufacturing process of the present invention.

FIG. 5 is a sectional view showing a conventional manufacturing process.

[Description of Signs] 1.2 Internal copper foil 3.4 Internal conductor 5.6 Organic insulating layer 7 Organic copper-clad laminate 8 Through hole 9.10 Nickel plating film (base) 11.12 Metal plated film (copper) 13 Organic insulator 14 15 Outer land 16 Conductive connection hole (nickel) 17 Via conductive connection hole (copper) 18 19 Conductive connection hole land 20 21 Plating permanent resist 22 · 23 · · · Outermost layer connection pad 24 · 25 · · · Outermost layer land 26 ... Solder layer 27 ... Circuit board of the present invention 28 ... Insulating substrate 29 ... Copper foil 30 ... Through hole 31 ... Copper plating film (base) 32 ... Conductive connection hole (Copper) 33 ... solder resist 34 ... nickel plating film (electroless) 35 ... coupling amount of copper plating solution (migration of copper ions) 36 ... through connection hole (nickel) 37 ... continuous connection hole land 38 ... conventional technology Such a circuit board, reference number p2461

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference)

Claims (2)

[Claims] 1. A double-sided or multilayer organic copper-clad laminate comprising an inner layer copper foil (1) and (2), organic insulating layers (5) and (6), and inner layer conductors (3) and (4). 7) A circuit board having via connection connection holes (17) electrically connected to the inner layer conductors (3) and (4) and outer layer lands (24) and (25). The whole surface and the conductive connection hole (1
The base metal film thickness of 6) is formed by nickel plating films (9) and (10) in the range of 0.6 to 12 μm.
The entire surface of the underlying nickel plating films (9) and (10) is coated with an electrolytic copper plating film (1) having a metal film thickness of 15 to 35 μm.
1) Via via connection hole (1) covered by (12)
7) is formed, and an organic insulator (13) is formed in the hole.
4) · (15), land of conductive connection hole (18) · (19)
After forming the resist, the electroless plating permanent resist (20).
A circuit board (27) according to the present invention, comprising: (1) forming outer layer connection pads (22) and (23) used for fixing mounted components. 2. The electric connection of the metal plating films (11) and (12) in the conductive connection hole (17) when passing through a reflow furnace under a high temperature, high humidity and high electric field environment. A circuit board (27) according to the present invention, wherein an organic insulator (13) is formed in the hole (17) to prevent deterioration of connection reliability.