JPH05283822A - Printed circuit board equipped with electromagnetic wave shield layer - Google Patents

Abstract

PURPOSE:To obtain a printed circuit board having inspecting patterns which can help distinguish correctly and easily non-defective units from defective units by making the distance of a gap between interdigital lines of an inspection metal layer almost equal to a gap between parallel lines of metal wiring. CONSTITUTION:An inspection pattern to be provided at the edge of an insulating substrate is composed of an electrical property measuring pattern 6a for measuring insulation resistance and dielectric breakdown strength, and a film-thickness measuring pattern 6b for measuring individual film thickness of layers. An inspection metal layer 62 has interdigital lines, and a gap between those lines has almost the same distance as a gap between parallel lines of metal wiring lines. As a result, as inspection insulating layer 63 can be formed on the inspecting metal layer 62 under the same condition as the case where an electric insulating layer is formed on parallel lines of metal wiring. Therefore, insulating resistance and dielectric breakdown strength of the parallel line positions can be found by measuring insulating resistance and dielectric breakdown strength in the inspecting patterns.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a metal wiring on an insulating base material, and an electromagnetic wave shield layer on the metal wiring for preventing malfunction of an electric component due to intrusion of an external electromagnetic wave through the electric insulation layer. Related to printed wiring boards. More specifically, the present invention relates to a printed wiring board having an inspection pattern at its end, which measures an insulation resistance and a withstand voltage of an electric insulation layer between the metal wiring and the electromagnetic wave shield layer and determines whether the insulation resistance is good or bad.

[0002]

2. Description of the Related Art A printed wiring board is constructed by forming metal wiring consisting of a copper foil or a copper plating layer on an insulating base material, and soldering an electric component such as an IC package to a predetermined portion. Used. A printed wiring board is known in which an electromagnetic wave shield layer is provided on the metal wiring via an electrical insulating layer in order to prevent malfunction of the electric component due to external electromagnetic waves entering the metal wiring.

The electromagnetic wave shield layer is, for example,
An electrically insulating resin such as a so-called solder resist is formed on the electric wiring as an electric insulating layer which is formed by applying a conductive paste containing a conductive metal filler and is interposed between the electromagnetic wave shield layer and the metal wiring. It is applied to and formed.

[0004]

However, the above-mentioned metal wiring generally includes an electric component mounting portion for mounting an electric component and a line portion for connecting the electric component mounting portions to each other. It has parallel lines formed in two or more lines parallel to each other with a certain interval.

Therefore, when the insulating resin is applied, bubbles are mixed in or the application amount is non-uniform, especially in the area between the parallel lines, so that a stable insulation resistance and withstand voltage can be obtained. It was difficult to secure. Then, in such a region where the desired insulation resistance and withstand voltage are not secured, the external electromagnetic wave, which should be able to be shielded, cannot be shielded, and a current flows between the electromagnetic wave shield layer and the metal wiring, so that it is mounted. There was a malfunction in the electrical components.

The present invention has been made in view of the above circumstances, and measures the insulation resistance and the withstand voltage of the above-mentioned electric insulation layer to obtain a good product having desired electrical properties and a non-defective product having the same. An object of the present invention is to provide a printed wiring board having an inspection pattern that can be easily and accurately distinguished from a non-defective product.

[0007]

That is, a printed wiring board according to the present invention is such that an electric component mounting portion on which an electric component is mounted and the electric component mounting portion are connected to each other on an insulating base material and are parallel to each other. An electromagnetic wave that includes a metal wiring that includes a line portion having two or more parallel lines that are parallel to each other, and that prevents an electrical component from malfunctioning due to an invasion of an external electromagnetic wave through the electrical insulation layer on the metal wiring. A shield layer is provided, and at the end portion of the insulating base material, an inspection metal layer, an inspection insulating layer, and an inspection conductive layer having the same material and thickness as those of the metal wiring, the electric insulation layer, and the electromagnetic wave shield layer, respectively. A printed wiring board having an inspection pattern for inspecting the resistance and withstand voltage of the electric insulation layer by a voltage applied between the inspection metal layer and the inspection conductive layer. Genus layer has a comb-teeth, and gaps between the comb teeth and having a gap substantially equal distance between the parallel lines of the metal wire.

In such a technical means, the comb-teeth-shaped metal layer for inspection imitates a parallel line of metal wiring, and the same condition as that for forming the electrically insulating layer on the parallel line of metal wiring. Since the inspection insulating layer can be formed on the inspection metal layer, the formation states of the both become substantially the same, and the insulation resistance and the withstand voltage of the inspection pattern are measured to measure the insulation resistance and the insulation resistance of the parallel line portion. It can be regarded as a withstand voltage. As described above, the decrease in the insulation resistance and the withstand voltage due to the formation state of the electric insulation layer is particularly remarkable in the parallel lines. Therefore, the insulation resistance and the withstand voltage of the parallel line portions are measured to measure the printed wiring board. It is possible to determine the quality of.

In order to approximate the insulation resistance and withstand voltage of the measured inspection pattern to the insulation resistance and insulation resistance of the metal wiring, the inspection metal layer is a metal wiring layer and the inspection insulating layer is an electrical insulation layer. The layer and the conductive layer for inspection are preferably formed simultaneously with the electromagnetic wave shielding layer.

Further, since the above-mentioned insulating layer for inspection is subject to dielectric breakdown during the measurement of the withstand voltage in this inspection pattern, the electrical insulating layer on the metal wiring layer is simultaneously destroyed during this dielectric breakdown. In order to prevent this, it is desirable that the inspection metal layer and the metal wiring, and the inspection conductive layer and the electromagnetic wave shield layer be formed in mutually insulated portions. In general,
It is formed at an unnecessary end portion which is cut and removed later.

[0011]

According to the present invention, the electric component mounting portion for mounting the electric component and the electric component mounting portions are connected to each other on the insulating base material to form two or more lines parallel to each other. A metal wiring including a line portion having parallel lines is provided, and an electromagnetic shielding layer for preventing malfunction of an electric component due to intrusion of an external electromagnetic wave is provided on the metal wiring via an electric insulating layer, At the end, the metal wiring,
An inspection metal layer, an inspection insulation layer, and an inspection conductive layer having the same material and thickness as those of the electrical insulation layer and the electromagnetic wave shield layer are laminated in this order. In a printed wiring board having an inspection pattern for inspecting the resistance and withstand voltage of an electric insulating layer by a voltage applied between them, the inspection metal layer has a comb tooth shape, and the gap between the comb teeth is the metal wiring. Since the distance between the parallel lines is substantially the same as that of the parallel lines, the test insulating layer should be formed on the test metal layer under the same conditions as the case where the electrical insulating layer is formed on the parallel lines of the metal wiring. And the formation state of both is substantially the same. Therefore, by measuring the insulation resistance and the withstand voltage in this inspection pattern, it can be regarded as the insulation resistance and the withstand voltage of the parallel line portion.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 2, the copper foils provided on both sides of the electrically insulating substrate 1 were selectively etched by a conventional method to form metal wirings 2 and 2 '. In the figure, 11 is a through hole for conducting the metal wirings 2 and 2'on both sides,
The inner wall is copper-plated. The metal wiring 2 is, as shown in the explanatory view of FIG.
1 and a line portion 22 that connects the electric component mounting portions 21 to each other, and the line portion is composed of a plurality of parallel lines.

Next, a liquid photoresist (PSR-1000 manufactured by Taiyo Ink Mfg. Co., Ltd.) is applied, exposed and developed to form an electric insulation layer 31 with high accuracy, and then the insulation resistance and insulation of the electric insulation layer 31 are obtained. To improve pressure resistance, a thermosetting solder resist (TC manufactured by Toyo Ink Mfg. Co., Ltd.)
-120) was applied and cured to form an electric insulation layer 3 having a thickness of about 40 μm, which is composed of a two-layer structure of the electric insulation layer 31 of the liquid photoresist and the electric insulation layer 32 of the thermosetting solder resist.

A conductive paste containing copper filler (NF20 manufactured by Tatsuta Electric Wire Co., Ltd.) is formed on the electric insulation layer 3.
00) was applied to a thickness of 20 μm to form an electromagnetic wave shield layer 4, and finally an overcoat layer 5 was formed to produce a printed wiring board.

Incidentally, in these series of manufacturing steps,
The inspection pattern 6 was formed at the same time. The inspection pattern 6 is provided at the end of the printed wiring board as shown in FIG. 3, and is cut and removed after measuring the insulation resistance and the withstand voltage.

As shown in FIGS. 1 (A) and 1 (B), this inspection pattern 6 includes an electrical property measurement pattern 6a for measuring insulation resistance and withstand voltage and a film thickness measurement pattern for measuring the film thickness of each layer. 6b.

The pattern 6a for measuring electrical properties is
A comb-like metal layer 6 for inspection, which is formed on the metal wiring 2 side of the electrically insulating substrate 1 at the same time with the same copper foil as this metal wiring.
2. An electrode 68 which is provided at the same time as the inspection metal layer 62 and applies a voltage to the inspection conductive layer 64, which will be described later, is formed in a shape that covers the inspection metal layer 62 and exposes the electrode 68. A two-layer structure inspection insulating layer 63 formed at the same time with the same material as the liquid photoresist 31 and the thermosetting solder resist 32, and extending from the end of the inspection insulating layer on the inspection insulating layer 63. And an overcoat layer 65, which is formed by connecting to the electrode 68 and is formed of the same material as the electromagnetic wave shield layer 4 at the same time. The insulating base material 1 is provided with a through hole 66 whose inner wall is plated with copper. Through the through hole 66, the inspection metal layer 6 is provided.
2 is configured so that a voltage can be applied. Further, the electrode 68 of the inspection conductive layer 64 is also provided with a through hole 67 whose inner wall is plated with copper, and a voltage can be applied to the inspection conductive layer 64 through the through hole 67. .. Therefore, by connecting a probe connected to a power source to the through holes 66 and 67, a voltage is applied between the inspection metal layer 62 and the inspection conductive layer 64, and the inspection insulation interposed therebetween is applied. The insulation resistance and withstand voltage of the layer 63 can be measured. Since the inspection insulating layer 63 and the electric insulating layer 3 are simultaneously formed of the same material, the measured insulation resistance and withstand voltage of the inspection insulating layer 63 are the same as those of the electric insulating layer 3. Can be regarded as

On the other hand, the film thickness measurement pattern 6b measures the film thickness of each layer and compares it with the insulation resistance and withstand voltage of the above-mentioned insulating layer 63 for inspection to show the relationship between the film thickness of each layer and the insulation resistance and withstand voltage. Can be reflected in the thickness design of each layer to obtain the desired insulation resistance and withstand voltage. For this purpose, the film thickness measurement pattern 6b includes the inspection metal layer 62, the inspection insulating layer 63, and the inspection conductive layer 6
4. The overcoat layer 65 has a shape in which each layer is laminated while shifting the position, and the film thickness can be measured by a roughness measuring device.

[0020]

According to the present invention, the inspection insulating layer can be formed on the inspection metal layer with the electric insulating layer being formed in the same state as the parallel line of the metal wiring. By measuring the resistance and the withstand voltage, it can be regarded as the insulation resistance and the withstand voltage of the parallel line portion. Therefore, it is possible to easily and accurately distinguish a good product having desired electrical properties and a defective product not having the desired electrical properties.

Therefore, it is possible to prevent supply of a defective product which causes a malfunction of the electric component due to the penetration of external electromagnetic waves, and to improve the reliability of the printed wiring board.

[Brief description of drawings]

FIG. 1A is an explanatory plan view of an inspection pattern according to an embodiment of the present invention. FIG. 1B is an explanatory cross-sectional view of the inspection pattern according to the embodiment of the present invention.

FIG. 2 is a cross-sectional explanatory diagram of a printed wiring board according to an example of the present invention.

FIG. 3 is an explanatory plan view of a printed wiring board according to an embodiment of the present invention.

[Explanation of symbols]

1 Electrically insulating base material. 11 through holes. 2 Metal wiring. 21 Electrical component mounting site. 1 and this electrical component mounting part 2
Line part that connects one to another. 3 Electrical insulation layer. 4 Electromagnetic wave shield layer. 5 Overcoat layer. 6 Inspection pattern. 62 Metal layer for inspection. 63 Insulation layer for inspection. Comb-tooth-shaped inspection metal layers 62 and 64 which are simultaneously formed of the copper foil of.

Claims (1)

[Claims] 1. An electric component mounting portion on which an electric component is mounted and the electric component mounting portions are connected to each other on an insulating base material,
A metal wiring including a line portion having two or more parallel lines that are parallel to each other is provided, and malfunction of electric components due to intrusion of external electromagnetic waves is prevented through an electric insulating layer on the metal wiring. Equipped with an electromagnetic wave shield layer,
At the end of the insulating base material, an inspection metal layer, an inspection insulating layer, and an inspection conductive layer having the same material and thickness as those of the metal wiring, the electric insulating layer and the electromagnetic wave shielding layer are laminated in this order. A printed wiring board having an inspection pattern for inspecting the resistance and withstand voltage of the electrical insulation layer by the voltage applied between the inspection metal layer and the inspection conductive layer,
A printed wiring provided with an electromagnetic wave shield layer, wherein the inspection metal layer has a comb-teeth shape, and a gap between the comb-teeth has substantially the same distance as a gap between parallel lines of the metal wiring. Board.