JPH04233800A - Printed board with electrostatic sheld and manufacture thereof - Google Patents

Abstract

PURPOSE:To offer a printed board with an electrostatic shield capable of corresponding easily to an increase in the density of the terminals of an electronic component and to offer a manufacturing method of being able to obtain efficiently such the printed board with an electrostatic shield. CONSTITUTION:An insulating layer 6 between wiring patterns is directly formed on a substrate 1 surface of an exposed part (a), at which foot patterns 2 are provided, of a substrate 1 in such a way as to avoid the part, at which the patterns 2 exist, and this layer 6 is formed in such a way that the wiring patterns including the patterns 2 are formed on the substrate 1 and thereafter, before the resin insulating layer 3 is formed, the layer 6 is formed by an etching technique.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed circuit board having a conductive layer for electrostatic shielding and a method for manufacturing the same.

0002

2. Description of the Related Art In recent years, as the packaging density of circuit boards has increased, so-called electrostatic shielded printed circuit boards, in which a conductive layer for electrostatic shielding is laminated on a wiring pattern, have come into widespread use.

[0003] Conventional examples of this printed circuit board with electrostatic shielding will be explained with reference to FIGS. In the figure, 1 is a substrate (base material), 2 is a foot pattern that becomes a solder connection part of a terminal of an electronic component such as an IC, 3 is an insulating resin layer, 4 is a conductive layer for electrostatic shielding, and 5 is a conductive layer for electrostatic shielding. is an overcoat layer.

FIG. 7 shows the manufacturing process of such a printed circuit board with an electrostatic shield, which includes a hole-drilling step A for the board 1, a through-hole plating step B, and a step of forming a copper foil to form the wiring pattern 2. Etching step C, forming step D of the insulating resin layer 3 using the silk screen printing method, forming step E of the copper paste layer also using the silk screen printing method to form the conductive layer 4, and overlaying also using the silk screen printing method. It consists of a coat layer forming step F, and is finally completed through a silk letter printing step G. In addition, here, from hole-drilling process A to through-hole plating process B, and copper foil etching process C.
The process up to this point is the same as the manufacturing method for ordinary printed circuit boards.

Returning to FIGS. 5 and 6, foot pattern 2 is as follows:
The part of the wiring pattern that becomes the solder connection part of the terminal of the electronic component such as the above-mentioned surface mount IC, and the part where this electronic component is attached is the exposed part of the board 1, and the foot pattern 2 is It is provided on the substrate surface of the exposed portion A.

[0006]

[Problem to be Solved by the Invention] The above-mentioned conventional technology
No consideration has been given to the narrowing of the foot pattern arrangement pitch dimension due to the increased terminal density of electronic components such as electronic components, resulting in lower soldering yields and increased repair man-hours due to the occurrence of solder bridges when mounting electronic components. was there.

[0007] The present invention provides a print with an electrostatic shield that can always sufficiently suppress the occurrence of solder bridges despite the narrowing of the foot pattern arrangement pitch dimension and can easily accommodate the high density of electronic component terminals. The object of the present invention is to provide a substrate, and a further object is to provide a manufacturing method that can efficiently obtain such a printed circuit board with an electrostatic shield.

[0008]

[Means for Solving the Problems] In order to achieve the above object, according to one aspect of the present invention, at least a portion between the foot patterns is directly filled in the exposed surface of the substrate on which the foot patterns are formed. According to another aspect of the present invention, the step of forming the insulating layer between wiring patterns is performed immediately after the step of forming wiring patterns by copper foil etching or the like. It was designed to be installed in

[0009]

[Operation] The inter-wiring pattern insulating layer existing between the foot patterns acts as a barrier against solder bridges that are about to occur between the foot patterns, and therefore the generation of solder bridges can be greatly suppressed. In addition, wet processes such as etching are used to form wiring patterns, but by providing the process of forming an insulating layer between wiring patterns immediately after the wiring pattern forming process, the number of man-hours can be reduced even if both of these processes are wet processes. The increase in the wiring pattern is minimized, high-definition processing by etching is possible, and an inter-wiring pattern insulating layer can be easily provided even between high-density foot patterns.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS A printed circuit board with an electrostatic shield and a method for manufacturing the same according to the present invention will be explained in detail below with reference to the illustrated embodiments. First, FIG. 1 is a cross-sectional view showing one embodiment of a printed circuit board with an electrostatic shield according to the present invention, and FIG. 2 is a plan view. In these figures, 6 is an insulating layer between wiring patterns, and A board (base material) 1, a foot pattern 2 which is part of the wiring pattern and serves as a solder connection part of an electronic component terminal, an insulating resin layer 3, a conductive layer 4 for electrostatic shielding, and an overcoat layer 5 are all shown in the figure. 5. This is the same as the conventional example explained in FIG. 6, and the exposed portion A of the board 1 to which the IC is attached is also the same.

As is clear from the figure, the inter-wiring pattern insulating layer 6 is formed directly on the surface of the substrate 1 in the exposed portion A where the foot pattern 2 of the substrate 1 is provided, avoiding the portion where the foot pattern 2 is present. It is formed by
After forming the wiring pattern including the foot pattern 2 on the substrate 1 using an etching technique, and before forming the insulating resin layer 3, the wiring pattern is formed using the same etching technique.As a result, high-definition processing is easy and high-density The inter-wiring pattern insulating layer 6 can also be formed between the foot patterns 2 with high precision.

Next, the function of a printed circuit board with an electrostatic shield according to an embodiment of the present invention having this inter-wiring pattern insulating layer 6 will be explained with reference to FIG. In FIG. 4, 8 is a normal soldered part, 9 is an excessively soldered part, and 10 is a normal soldered part.
11 is a lead part of an electronic component such as an IC, and 11 is a molded part of an electronic component. When the lead part 10 is soldered to the foot pattern 2, what happens if the soldering is done as shown in the normal soldered part 8? There is no problem. However, in this embodiment, since the inter-wiring pattern insulating layer 6 exists between the foot patterns 2, even if excessive solder flows out from a certain foot pattern 2 due to an excessive solder state, this excessive solder will not flow out. The outflow of solder is blocked by the inter-wiring pattern insulating layer 6, and the outflow to the adjacent foot pattern 2 is prevented, resulting in only an excessively soldered part 9, so that the risk of solder bridges occurring is sufficiently suppressed. .

Comparing this with the conventional example explained in FIGS. 5 and 6, in this conventional printed circuit board with electrostatic shielding, the structure of each foot pattern 2 is as shown in FIG. Since there is no barrier between them, if there is excessive solder in the foot pattern, it will immediately become solder bridges 7, resulting in frequent occurrence of solder bridges.

Therefore, according to the embodiments of the present invention shown in FIGS. 1 and 2, it is possible to reliably suppress the occurrence of solder bridges when mounting electronic components, thereby reducing the height of the terminals of electronic components such as ICs. It is possible to easily provide a printed circuit board with an electrostatic shield that fully corresponds to increased density and is free from the risk of a decrease in soldering yield due to frequent occurrence of solder bridges during electronic component mounting and an increase in the number of repair steps.

Next, a method of manufacturing a printed circuit board with an electrostatic shield according to the embodiment of the present invention explained in FIGS. 1 and 2 will be explained with reference to FIG. First, a hole drilling process A is performed on the substrate 1 using an N/C drilling machine or the like. Next, a through-hole plating process B is performed, which includes primary chemical copper plating followed by secondary electroplating. Subsequently, a copper foil etching step C is performed to form the wiring pattern 2 by using an etching resist such as a dry film and etching using cupric chloride.

After this, in the conventional example explained in FIGS. 5 and 6, the insulating resin layer 3 is then formed by silk screen printing.
The manufacturing process proceeds to step D of forming the conductive layer 4, step E of forming a copper paste layer by a silk screen printing method, step F of forming an overcoat layer by a silk screen printing method, and step G of printing silk characters. In this embodiment, after the copper foil etching step C and before proceeding to the forming step D of the insulating resin layer 3, the inter-wiring pattern insulating layer forming step H is performed.

To explain the process H of forming an insulating layer between wiring patterns, as mentioned above, this process requires a manufacturing process capable of forming a pattern with a high definition width. Resist etching is used. First, resist ink is applied to the front surface of the substrate 1 with a squeegee, and then dried (90 degrees Celsius, 20 degrees Celsius).
After that, the steps of exposure, development, and drying (140 degrees Celsius, 45 minutes) are performed.

In this way, the step H of forming an insulating layer between wiring patterns
After that, the steps are the same as in the conventional example, step D of forming the insulating resin layer 3 by the silk screen printing method, and step D of forming the conductive layer 4.
Step E of forming a copper paste layer by silk screen printing to form a copper paste layer, step F of forming an overcoat layer by silk screen printing, and step G of silk letter printing. layer 3
As mentioned above, the forming process D is based on the silk screen printing method, and therefore, it is difficult to form a pattern with a high definition width. By curing, an insulating resin layer is formed.

Next, the step E of forming the copper paste layer consists of printing the copper paste using a silk screen printing method, followed by a heat curing treatment, thereby forming the conductive layer 4 for electrostatic shielding. The subsequent overcoat layer forming step F is the same as the insulating resin layer 3 forming step D, and consists of printing ink on necessary parts of the substrate 1, drying process, and curing process, and forms the overcoat layer 5 made of insulating resin. is formed. Note that the insulating resin layer 3 and the overcoat layer 5
Both use epoxy resin.

Therefore, according to the embodiment shown in FIG. 3, the etching technique using photoresist is adopted as the technique for forming the inter-wiring pattern insulating layer 6 in the inter-wiring pattern insulating layer forming process H, so that high-definition It is easy to form a pattern with a wide width, and it can sufficiently cope with the narrowing of the foot pattern arrangement pitch dimension accompanying the increase in the density of terminals of electronic components such as ICs. Since step H is performed after the copper foil etching step C and before proceeding to the insulating resin layer 3 forming step D, wet steps such as etching can be performed continuously, and substantially The inter-wiring pattern insulating layer 6 having a high-definition width pattern can be easily formed without increasing the number of wet processes and with almost no increase in cost.

[0021]

[Effects of the Invention] According to the present invention, the following effects can be fully expected.

(2) The workability of soldering surface-mounted electronic components such as ICs to electrostatically shielded printed circuit boards can be greatly improved.

[0023] The range of applications of printed circuit boards with electrostatic shielding can be greatly expanded.

(2) Connection reliability of a printed circuit board with an electrostatic shield can be sufficiently improved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of a printed circuit board with an electrostatic shield according to the present invention.

FIG. 2 is a front view showing an example of a printed circuit board with an electrostatic shield.

FIG. 3 is a process diagram showing an embodiment of a method for manufacturing a printed circuit board with an electrostatic shield according to the present invention.

FIG. 4 is a sectional view showing a soldering state in an embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a conventional example of a printed circuit board with an electrostatic shield.

FIG. 6 is a front view showing a conventional example of a printed circuit board with an electrostatic shield.

FIG. 7 is a process diagram showing a conventional method for manufacturing a printed circuit board with an electrostatic shield.

FIG. 8 is a sectional view showing a soldered state in a conventional example of a printed circuit board with an electrostatic shield.

[Explanation of symbols]

1 Board 2 Foot pattern 3 Insulating resin layer 4 Conductive layer for electrostatic shielding 5 Overcoat layer 6 Insulating layer between wiring patterns 7 Solder bridge part 8 Normal soldering part 9 Excessive soldering part 10 Lead part of electronic components 11 Mold part of electronic parts B Exposed part of the board

Claims (3)

[Claims] 1. A printed circuit board in which an electrostatic shield layer made of a conductive layer is laminated on a wiring pattern formed on a substrate surface with an insulating layer interposed therebetween, and an overcoat layer is provided on this electrostatic shield layer. An inter-wiring pattern insulating layer formed in a process different from the insulating layer and overcoat layer is formed on at least a part of the exposed surface of the substrate where a part of the wiring pattern is present. Printed circuit board with electric shield. 2. A method for manufacturing a printed circuit board with an electrostatic shield, comprising at least the steps of forming a wiring pattern on a substrate surface, forming an insulating layer, and forming an electrostatic shield layer, Between the step of forming the wiring pattern and the step of forming the insulating layer, a step of forming an inter-wiring pattern insulating layer on at least a part of the exposed surface of the substrate where a part of the wiring pattern is present is provided. A method for manufacturing a printed circuit board with an electrostatic shield, characterized in that: 3. The method of manufacturing a printed circuit board with an electrostatic shield according to claim 2, wherein the step of forming the inter-wiring pattern insulating layer is a step of forming an insulating layer using photoresist.